Posts Tagged ‘Melanoma’

Live Conference Coverage @Medcitynews Converge 2018 Philadelphia: The Davids vs. the Cancer Goliath Part 2

8:40 – 9:25 AM The Davids vs. the Cancer Goliath Part 2

Startups from diagnostics, biopharma, medtech, digital health and emerging tech will have 8 minutes to articulate their visions on how they aim to tame the beast.

Start Time End Time Company
8:40 8:48 3Derm
8:49 8:57 CNS Pharmaceuticals
8:58 9:06 Cubismi
9:07 9:15 CytoSavvy
9:16 9:24 PotentiaMetrics

Liz Asai, CEO & Co-Founder, 3Derm Systems, Inc. @liz_asai
John M. Climaco, CEO, CNS Pharmaceuticals @cns_pharma 

John Freyhof, CEO, CytoSavvy
Robert Palmer, President & CEO, PotentiaMetrics @robertdpalmer 
Moira Schieke M.D., Founder, Cubismi, Adjunct Assistant Prof UW Madison @cubismi_inc


3Derm Systems

3Derm Systems is an image analysis firm for dermatologic malignancies.  They use a tele-medicine platform to accurately triage out benign malignancies observed from the primary care physician, expediate those pathology cases if urgent to the dermatologist and rapidly consults with you over home or portable device (HIPAA compliant).  Their suite also includes a digital dermatology teaching resource including digital training for students and documentation services.


CNS Pharmaceuticals

developing drugs against CNS malignancies, spun out of research at MD Anderson.  They are focusing on glioblastoma and Berubicin, an anthracycline antiobiotic (TOPOII inhibitor) that can cross the blood brain barrier.  Berubicin has good activity in a number of animal models.  Phase I results were very positive and Phase II is scheduled for later in the year.  They hope that the cardiotoxicity profile is less severe than other anthracyclines.  The market opportunity will be in temazolamide resistant glioblastoma.


They are using machine learning and biomarker based imaging to visualize tumor heterogeneity. “Data is the new oil” (Intel CEO). We need prediction machines so they developed a “my body one file” system, a cloud based data rich file of a 3D map of human body.




CytoSavvy is a digital pathology company.  They feel AI has a fatal flaw in that no way to tell how a decision was made. Use a Shape Based Model Segmentation algorithm which uses automated image analysis to provide objective personalized pathology data.  They are partnering with three academic centers (OSU, UM, UPMC) and pool data and automate the rule base for image analysis.

CytoSavvy’s patented diagnostic dashboards are intuitive, easy–to-use and HIPAA compliant. Our patented Shape-Based Modeling Segmentation (SBMS) algorithms combine shape and color analysis capabilities to increase reliability, save time, and improve decisions. Specifications and capabilities for our web-based delivery system follow.

link to their white paper: https://www.cytosavvy.com/resources/healthcare-ai-value-proposition.pdf


They were developing a diagnostic software for cardiology epidemiology measuring outcomes however when a family member got a cancer diagnosis felt there was a need for outcomes based models for cancer treatment/care.  They deliver real world outcomes for persoanlized patient care to help patients make decisions on there care by using a socioeconomic modeling integrated with real time clinical data.

Featured in the Wall Street Journal, using the informed treatment decisions they have generated achieve a 20% cost savings on average.  There research was spun out of Washington University St. Louis.

They have concentrated on urban markets however the CEO had mentioned his desire to move into more rural areas of the country as there models work well for patients in the rural setting as well.

Please follow on Twitter using the following #hash tags and @pharma_BI 









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President Carter’s Status

Author: Larry H. Bernstein, MD, FCAP



Most Experts Not Surprised by Carter’s Status 

But early response does not mean ‘cure’




by Charles Bankhead
Staff Writer, MedPage Today


Former President Jimmy Carter’s announcement that he is free of metastatic melanoma surprised many people but, not most melanoma specialists contacted by MedPage Today.

With the evolution of modern radiation therapy techniques and targeted drugs, more patients with metastatic melanoma achieve complete and partial remissions, including remission of small brain metastases like the ones identified during the evaluation and initial treatment of Carter. However, the experts — none of whom have direct knowledge of Carter’s treatment or medical records — cautioned that early remission offers no assurance that the former president is out of the woods.

“If I had a patient of my own with four small brain mets undergoing [stereotactic radiation therapy], I would tell them that I fully expected the radiation to take care of those four lesions,” said Vernon K. Sondak, MD, of Moffitt Cancer Center in Tampa. “The fact that President Carter reports that it has done just that is not a surprise to me at all.

“I would also tell my patient that the focused radiation only treats the known cancer in the brain, and that if other small areas of cancer are present, they will likely eventually grow large enough to need radiation or other treatment as well, and that periodic brain scans will be required to monitor for this possibility.”

Carter also is being treated with the immune checkpoint inhibitor pembrolizumab (Keytruda), which is known to stimulate immune cells that then migrate to tumor sites to eradicate the lesions, noted Anna Pavlick, DO, of NYU Langone Medical Center in New York City.

“Melanoma is no longer a death sentence, and we are really changing what happens to patients,” said Pavlick. “It really is amazing.”

Carter’s melanoma story began to emerge in early August when he had surgery to remove what was described as “a small mass” from his liver. Following the surgery, Carter announced that his doctors had discovered four small melanoma lesions in his brain, confirming a suspicion the specialists had shared with him at the time of the surgery.

Carter subsequently underwent focused radiation therapy to eradicate the brain lesions and initiated a 12-week course of treatment with pembrolizumab. The radiation therapy-targeted therapy combination was a logical option for Carter, given observations that the PD-L1 inhibitor has synergy with radiation, noted Stergios Moschos, MD, of the University of North Carolina Lineberger Comprehensive Cancer Center at Chapel Hill.

“I have seen this in other patients with metastatic melanoma,” said Gary K. Schwartz, MD, of Columbia University Medical Center in New York City. “It is remarkable but absolutely possible within the realm of immunotherapy today.”

Although Carter’s announcement is undeniably good news, the optimism should be tempered by a long-term perspective, suggested Nagla Abdel Karim, MD, PhD, of the University of Cincinnati Medical Center.

“We do have similar stories; however, we would be careful to call it a ‘complete remission’ and ‘disease control’ and not a ‘cure,’ so far,” said Karim. “We would resume therapy and follow-up any autoimmune side effects. Most important is the quality of life, which he seems to enjoy, and we are very happy with that.”

Darrell S. Rigel, MD, also of NYU Langone Medical Center, represented the lone dissenter among specialists who responded to MedPage Today‘s request for comments.

“I’m happy for him, but it’s very unusual, especially in older men, who usually have a worse prognosis,” said Rigel. “He is on a new drug that may have a little more promise, but there is no definitive cure at this point.”



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Single Cell Shines Light on Cell Malignant Transformation

Larry H. Bernstein, MD, FCAP, Curator



Single Cell Lights Beacon to Cancer Origins



For the first time scientists are able to visualize the origin of cancer cells and track their progression through tumorigenesis. [Dr. Leonard Zon, Boston Children’s Hospital].

Conundrums exist in every facet of our daily lives and are often dismissed as either general annoyances or fleeting curiosities. Yet for scientists, solving common scientific enigmas can often lead to a watershed moment within their respective discipline.  For instance, researchers have been perplexed for decades as to why the vast number of cells that have cancer genes never morph into cancerous tumors.

Researchers at Boston Children’s Hospital have published results from a new study, which visualized the origins of cancer from the first affected cell and watched its spread within a live animal. The research team is hopeful that their findings could change the way scientists understand melanoma and other cancers, as well as open doors to new therapeutic interventions.

“An important mystery has been why some cells in the body already have mutations seen in cancer, but do not yet fully behave like the cancer,” stated lead author Charles Kaufman, M.D., Ph.D., a postdoctoral fellow in the laboratory of Howard Hughes Medical Institute investigator Leonard Zon, M.D. at Boston Children’s Hospital. “We found that the beginning of cancer occurs after activation of an oncogene or loss of a tumor suppressor, and involves a change that takes a single cell back to a stem cell state.”

The findings from this study were published online today in Science through an article entitled “A zebrafish melanoma model reveals emergence of neural crest identity during melanoma initiation.”

The Boston researchers tracked the development of melanoma in live zebrafish that had been genetically engineered to have the human cancer mutation BRAFV600E—found in most benign moles—and the p53 tumor suppressor gene removed. Moreover, the fish contained a GFP-crestin gene that would light up if it was turned on, a beacon indicating activation of a genetic program characteristic of stem cells. Typically this program is turned off after embryonic development. Occasionally, however, crestin and other genes in the program turn back on in individual cells.

“Every so often we would see a green spot on a fish,” noted Dr. Zon, who is the director of the Stem Cell Research Program at Boston Children’s, member of the Harvard Stem Cell Institute, and senior author on the current study. “When we followed them, they became tumors 100 percent of the time.”

When Dr. Zon and his colleagues looked to see what was different in these early cancer cells, they found that crestin and the other activated genes are the same ones turned on during zebrafish embryonic development, specifically in the stem cells that give rise to the pigment cells known as melanocytes within a structure called the neural crest.

“What’s cool about this group of genes is that they also get turned on in human melanoma,” Dr. Zon said. “It’s a change in cell fate, back to neural crest status.”

While trying to track these glowing cells in live fish was exceedingly difficult, Dr. Kaufman managed to isolate and characterize 30 fish with a small green glowing cluster of cells. Interestingly, in all 30 cases, the clusters grew into melanomas. In two fish, Dr. Kaufman was able to see a single green-glowing cell and watch it divide to ultimately become a tumor mass.

“It’s estimated that only one in tens or hundreds of millions of cells in a mole eventually become a melanoma,” explained Dr. Kaufman. “Because we can also efficiently breed many fish, we can look for these very rare events. The rarity is very similar in both humans and fish, which suggests that the underlying process of melanoma formation is probably much the same in humans.”

The investigators are optimistic that the results from their study could lead to new genetic tests for suspicious moles to see whether the cells are behaving like neural crest cells, indicating that the stem-cell program has been turned on. Additionally, the scientists are investigating the regulatory elements that turn on the genetic program, often called super-enhancers. These control elements have analogous epigenetic functions in zebrafish and human melanoma, potentially providing druggable targets to stop a mole from becoming cancerous.



A zebrafish melanoma model reveals emergence of neural crest identity during melanoma initiation
Visualizing the beginnings of melanoma

In cancer biology, a tumor begins from a single cell within a group of precancerous cells that share genetic mutations. Kaufman et al. used a zebrafish melanoma model to visualize cancer initiation (see the Perspective by Boumahdi and Blanpain). They used a fluorescent reporter that specifically lit up neural crest progenitors that are only present during embryogenesis or during adult melanoma tumor formation. The appearance of this tumor correlated with a set of gene regulatory elements, called super-enhancers, whose identification and manipulation may prove beneficial in detecting and preventing melanoma initiation.

Science, this issue p. 10.1126/science.aad3867; see also p. 453


Structured Abstract


The “cancerized field” concept posits that cells in a given tissue sharing an oncogenic mutation are cancer-prone, yet only discreet clones within the field initiate tumors. Studying the process of cancer initiation has remained challenging because of (i) the rarity of these events, (ii) the difficulty of visiualizing initiating clones in living organisms, and (iii) the transient nature of a newly transformed clone emerging before it expands to form an early tumor. A more complete understanding of the molecular processes that regulate cancer initiation could provide important prognostic information about which precancerous lesions are most prone to becoming cancer and also implicate druggable molecular pathways that, when inhibited, may prevent the cancer from ever starting.


The majority of benign nevi carry oncogenic BRAFV600E mutations and can be considered a cancerized field of melanocytes, but they only rarely convert to melanoma. In an effort to define events that initiate cancer, we used a melanoma model in the zebrafish in which the humanBRAFV600E oncogene is driven by the melanocyte-specific mitfa promoter. When bred into a p53mutant background, these fish develop melanoma tumors over the course of many months. The zebrafish crestin gene is expressed embryonically in neural crest progenitors (NCPs) and is specifically reexpressed only in melanoma tumors, making it an ideal candidate for tracking melanoma from initiation onward.


We developed a crestin:EGFP reporter that recapitulates the embryonic neural crest expression pattern of crestin and its expression in melanoma tumors. We show through live imaging of transgenic zebrafish crestin reporters that within a cancerized field (BRAFV600Emutant; p53-deficient), a single melanocyte reactivates the NCP state, and this establishes that a fate change occurs at melanoma initiation in this model. Early crestin+ patches of cells expand and are transplantable in a manner consistent with their possessing tumorigenic activity, and they exhibit a gene expression pattern consistent with the NCP identity readout by the crestin reporter. Thecrestin element is regulated by NCP transcription factors, including sox10. Forced sox10overexpression in melanocytes accelerated melanoma formation, whereas CRISPR/Cas9 targeting of sox10 delayed melanoma onset. We show activation of super-enhancers at NCP genes in both zebrafish and human melanomas, identifying an epigenetic mechanism for control of this NCP signature leading to melanoma.


This work using our zebrafish melanoma model and in vivo reporter of NCP identity allows us to see cancer from its birth as a single cell and shows the importance of NCP-state reemergence as a key event in melanoma initiation from a field of cancer-prone melanocytes. Thus, in addition to the typical fixed genetic alterations in oncogenes and tumor supressors that are required for cancer development, the reemergence of progenitor identity may be an additional rate-limiting step in the formation of melanoma. Preventing NCP reemergence in a field of cancer-prone melanocytes may thus prove therapeutically useful, and the association of NCP genes with super-enhancer regulatory elements implicates the associated druggable epigenetic machinery in this process.



Neural crest reporter expression in melanoma.

The crestin:EGFP transgene is specifically expressed in melanoma inBRAFV600E/p53 mutant melanoma-prone zebrafish. (Top) A single cell expressingcrestin:EGFP expands into a small patch of cells over the course of 2 weeks, capturing the initiation of melanoma formation (bracket). (Bottom) A fully formed melanoma specifically expresses crestin:EGFP, whereas the rest of the fish remains EGFP-negative.


Neural crest reporter expression in melanoma.

The crestin:EGFP transgene is specifically expressed in melanoma inBRAFV600E/p53 mutant melanoma-prone zebrafish. (Top) A single cell expands into a small patch of cells over the course of 2 weeks, capturing the initiation of melanoma formation (bracket). (Bottom) A fully formed melanoma specifically expresses crestin:EGFP, whereas the rest of the fish remains EGFP-negative.

The “cancerized field” concept posits that cancer-prone cells in a given tissue share an oncogenic mutation, but only discreet clones within the field initiate tumors. Most benign nevi carry oncogenic BRAFV600E mutations but rarely become melanoma. The zebrafish crestin gene is expressed embryonically in neural crest progenitors (NCPs) and specifically reexpressed in melanoma. Live imaging of transgenic zebrafish crestin reporters shows that within a cancerized field (BRAFV600Emutant; p53-deficient), a single melanocyte reactivates the NCP state, revealing a fate change at melanoma initiation in this model. NCP transcription factors, including sox10, regulate crestin expression. Forced sox10 overexpression in melanocytes accelerated melanoma formation, which is consistent with activation of NCP genes and super-enhancers leading to melanoma. Our work highlights NCP state reemergence as a key event in melanoma initiation.


A Cancer’s Surprise Origins, Caught in Action

Harvard University

Most of the time skin moles are harmless, but they occasionally turn into melanoma, a life-threatening skin cancer. Leonard Zon and colleagues found that this happens when a single cell regresses back to a stem cell state and starts to divide and invade the surrounding tissue. (Image: Courtesy of Boston Children's Hospital)


Most of the time skin moles are harmless, but they occasionally turn into melanoma, a life-threatening skin cancer. Leonard Zon and colleagues found that this happens when a single cell regresses back to a stem cell state and starts to divide and invade the surrounding tissue. (Image: Courtesy of Boston Children’s Hospital)


Researchers at Harvard-affiliated Boston Children’s Hospital have, for the first time, visualized the origins of cancer from the first affected cell and watched its spread in a live animal. Their work, published in the Jan. 29 issue of Science, could change the way scientists understand melanoma and other cancers and lead to new, early treatments before the cancer has taken hold.

“An important mystery has been why some cells in the body already have mutations seen in cancer, but do not yet fully behave like the cancer,” said the paper’s first author, Charles Kaufman, a postdoctoral fellow in the Zon Laboratory at Boston Children’s Hospital. “We found that the beginning of cancer occurs after activation of an oncogene or loss of a tumor suppressor, and involves a change that takes a single cell back to a stem cell state.”

That change, Kaufman and colleagues found, involves a set of genes that could be targeted to stop cancer from ever starting.

The study imaged live zebrafish over time to track the development of melanoma. All the fish had the human cancer mutation BRAFV600E — found in most benign moles — and had also lost the tumor suppressor gene p53.

Kaufman and colleagues engineered the fish to light up in fluorescent green if a gene called crestin was turned on — a “beacon” indicating activation of a genetic program characteristic of stem cells. This program normally shuts off after embryonic development, but occasionally, in certain cells and for reasons not yet known, crestin and other genes in the program turn back on.

“Every so often we would see a green spot on a fish,” said Leonard Zon, director of the Stem Cell Research Program at Boston Children’s and senior investigator on the study. “When we followed them, they became tumors 100 percent of the time.”

The cell that caused melanoma

When Kaufman, Zon, and colleagues looked to see what was different about these early cancer cells, they found that crestin and the other activated genes were the same ones turned on during zebrafish embryonic development — specifically, in the stem cells that give rise to the pigment cells known as melanocytes, within a structure called the neural crest.

“What’s cool about this group of genes is that they also get turned on in human melanoma,” said Zon, who is also a member of the Harvard Stem Cell Institute and a Howard Hughes Medical Institute investigator. “It’s a change in cell fate, back to neural crest status.”

Finding these cancer-originating cells was tedious. Wearing goggles and using a microscope with a fluorescent filter, Kaufman examined the fish as they swam around, shooting video with his iPhone. Scanning 50 fish could take two to three hours. In 30 fish, Kaufman spotted a small cluster of green-glowing cells about the size of the head of a Sharpie marker — and in all 30 cases, these spots grew into melanomas. In two cases, he was able to see on a single green-glowing cell and watch it divide and ultimately become a tumor mass.

“It’s estimated that only one in tens or hundreds of millions of cells in a mole eventually becomes a melanoma,” said Kaufman, who is also an instructor at the Harvard-affiliated Dana-Farber Cancer Institute. “Because we can also efficiently breed many fish, we can look for these very rare events. The rarity is very similar in both humans and fish, which suggests that the underlying process of melanoma formation is probably much the same in humans.”

Zon, the Grousbeck Professor of Pediatric Medicine at Harvard Medical School, and Kaufman believe that their findings could lead to a new genetic test for suspicious moles to see whether the cells are behaving like neural crest cells, indicating that the stem-cell program has been turned on. They are also investigating the regulatory elements that turn on the genetic program (known as super-enhancers). These DNA elements have epigenetic functions that are similar in zebrafish and human melanoma, and could potentially be targeted with drugs to stop a mole from becoming cancerous.

A paradigm shift for cancer?

Zon and Kaufman posit a new model for cancer formation, going back to a decades-old concept of “field cancerization.” They propose that normal tissue becomes primed for cancer when oncogenes are activated and tumor suppressor genes are silenced or lost, but that cancer develops only when a cell in the tissue reverts to a more primitive, embryonic state and starts dividing. They believe this model may apply to most if not all cancers, not just melanoma.

The study was supported by the National Institutes of Health, the National Institute of Arthritis and Musculoskeletal and Skin Diseases, the Ellison Foundation, the Melanoma Research Alliance, the V Foundation, and the Howard Hughes Medical Institute. Zon is a founder and stockholder of Fate, Inc., and Scholar Rock.

Source: Harvard Gazette



The little fish that could

Zebrafish help HSCI researchers fight human disease

Leonard Zon, MD, could be called HSCI’s most prolific aquarist. The Executive Committee Chair estimates that he has over 300,000 fish spread throughout his laboratories at the Harvard Department of Stem Cell and Regenerative Biology and Boston Children’s Hospital

His collection isn’t very diverse, composed as it is entirely of zebrafish—minnow-like, freshwater, tropical fish that grow about an inch-and-a-half long. But Zon isn’t interested in winning best in show. Instead, he is leading a scientific movement to show that his striped fish could be humanity’s new animal of choice for drug discovery and studying disease.

Not only does the zebrafish require fewer facility resources than science’s go-to organism, the mouse, but fish are quicker to reproduce, easier to experimentally manipulate, and at least 70 percent of human protein-coding genes have analogs in the zebrafish, including those related to skin cancer, muscular dystrophy, and T cell leukemia.

“The zebrafish is now emerging as another powerful organism for the modeling and study of human diseases, and it is conceivable that zebrafish models will complement mouse models in the future,” Zon wrote in the December issue of Trends in Cell Biology, pointing out the accelerating increase in studies on zebrafish, from about 150 in 1995 to over 2,000 in 2013.

As a pediatric oncologist, Zon’s main purpose in using zebrafish is to help cancer patients. He is the first scientist to successfully apply basic research from the zebrafish to develop an FDA-approved treatment for human melanoma, and is now applying similar methods to find therapies for muscle and blood cancers.

One cancer Zon is pursuing is rhabdomyosarcoma, a rare muscle cancer diagnosed primarily in early childhood. Zebrafish, under certain conditions, develop tumors very similar to the human disease. He is currently using zebrafish embryos to identify which genes transform a normal muscle stem cell into a malignant tumor, as well as searching for factors that might suppress the cancer.

“One of the things that’s really interesting in zebrafish is that the embryos are completely transparent and you can watch the tumors invade the normal tissues,”
he said. “That’s a process that you can’t study in any other organism.”

Postdocs in Zon’s lab can expose the zebrafish embryos to multiple chemicals and literally watch changes in the fish’s development. In 2007, this technique led to the discovery of a type of prostaglandin that expands blood stem cells about 300 to 400 percent. Last fall, the prostaglandin found in Zon’s lab passed Phase Ib clinical trials as a therapy that increases the success of cord blood transplants.

A similar screen led to a major paper last November, in which Zon and fellow HSCI Executive Committee member Amy Wagers, PhD, showed that the same chemicals that stimulate muscle development in zebrafish can also be used to differentiate human stem cells into muscle cells in the laboratory, an historically challenging task that, now overcome, makes muscle cell therapy a more realistic possibility.

“This research demonstrates that over 300 million years of evolution, the pathways used in the fish are conserved through vertebrates all the way up to the human,” Zon said.

His passion for and success with zebrafish has helped make the animal a staple in HSCI faculty member laboratories across Boston, and an unexpected symbol for stem cell research.

Human muscle stem cell therapy gets help from zebrafish

November 7, 2013

Harvard Stem Cell Scientists have discovered that the same chemicals that stimulate muscle development in zebrafish can also be used to differentiate human stem cells into muscle cells in the laboratory, an historically challenging task that, now overcome, makes muscle cell therapy a more realistic clinical possibility.

The work, published this week in the journal Cell, began with a discovery by Boston Children’s Hospital researchers, led by Leonard Zon, MD, and graduate student Cong (Tony) Xu, who tested 2,400 different chemicals in cultures of zebrafish embryo cells to determine if any could increase the numbers of muscle cells formed. Using fluorescent reporter fish in which muscle cells were visible during their creation, the researchers found six chemicals that were very effective at promoting muscle formation.

Zon shared his results with Harvard Department of Stem Cell and Regenerative Biologyprofessor Amy Wagers, PhD, and Mohammadsharif Tabebordbar, a graduate student in her laboratory, who tested the six chemicals in mice. One of the six, called forskolin, was found to increase the numbers of muscle stem cells from mice that could be obtained when these cells were grown in laboratory dishes. Moreover, the cultured cells successfully integrated into muscle when transplanted back into mice.

Inspired by the successful application of these chemicals in mice, Salvatore Iovino, PhD, a joint postdoctoral fellow in the Wagers lab and the lab of C. Ronald Kahn, MD, at the Joslin Diabetes Center, investigated whether the chemicals would also affect human cells and found that a combination of three chemicals, including forskolin, could induce differentiation of human induced pluripotent stem (iPS) cells, made by reprogramming skin cells. Exposure of iPS cells to these chemicals converted them into skeletal muscle, an outcome the Wagers and Kahn labs had been striving to achieve for years using conventional methods. When transplanted into a mouse, the human iPS-derived muscle cells also contributed to muscle repair, offering early promise that this protocol could provide a route to muscle stem cell therapy in humans.

The interdisciplinary, cross-laboratory collaboration between Zon, Wagers, and Kahn highlights the advantage of open exchange between researchers. “If we had done this screen directly on human iPS cells, it would have taken at least 10 times as long and cost 100 times as much,” said Wagers. “The zebrafish gave us a big advantage here because it has a fast generation time, rapid development, and can be easily and relatively cheaply screened in a culture dish.”

“This research demonstrates that over 300 million years of evolution, the pathways used in the fish are conserved through vertebrates all the way up to the human,” said Wagers’ fellow HSCRB professor Leonard Zon, chair of the Harvard Stem Cell InstituteExecutive Committee and director of the stem cell program at Boston Children’s Hospital. “We can now make enough human muscle progenitors in a dish to allow us to model diseases of the muscle lineage, like Duchenne muscular dystrophy, conduct drug screens to find chemicals that correct those disease, and in the long term, efficiently transplant muscle stem cells into a patient.”

In a similar biomedical application, Kahn, who is chief academic officer at the Joslin, plans to apply the new ability to quickly produce muscle stem cells for diabetes research. His lab will generate iPS-derived muscle cells from people who are at risk for diabetes and people who have diabetes to identify alterations that lead to insulin resistance in the muscle.

Going forward, Zon plans to apply this platform of cross-species discovery to other stem cell lines, including those involved in blood and eye development. “We have a new system to use to study tissue development, and it’s not just muscle that can be studied, every single organ can be studied in the zebrafish system,” he said.

The research was funded by the Harvard Stem Cell Institute, the Howard Hughes Medical Institute, the National Institutes of Health, the Novo Nordisk Diabetes Center, and the Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center.

Photo:Newly created muscle progenitor cells (green) and muscle fibers (red) in a zebrafish embryo. (credit: Zon Lab)


Dynamics and heterogeneity of a fate determinant during transition towards cell differentiation

Yan is an ETS-domain transcription factor responsible for maintaining Drosophila eye cells in a multipotent state. Yan is at the core of a regulatory network that determines the time and place in which cells transit from multipotency to one of several differentiated lineages. Using a fluorescent reporter for Yan expression, we observed a biphasic distribution of Yan in multipotent cells, with a rapid inductive phase and slow decay phase. Transitions to various differentiated states occurred over the course of this dynamic process, suggesting that Yan expression level does not strongly determine cell potential. Consistent with this conclusion, perturbing Yan expression by varying gene dosage had no effect on cell fate transitions. However, we observed that as cells transited to differentiation, Yan expression became highly heterogeneous and this heterogeneity was transient. Signals received via the EGF Receptor were necessary for the transience in Yan noise since genetic loss caused sustained noise. Since these signals are essential for eye cells to differentiate, we suggest that dynamic heterogeneity of Yan is a necessary element of the transition process, and cell states are stabilized through noise reduction.

As animal cells develop, they pass through different states to mature into specific cell types. For some cells, this development depends on the cell’s ability to switch between two stable states, a property called bistability.

Many bistable systems operate during development and often feature proteins called transcription factors that regulate a few cell states in specific tissues. These proteins activate or repress a range of target genes, and cells can adjust the levels of the transcription factors to bring about transitions between states. In fruit flies, two transcription factors, called Yan and Pnt, regulate numerous processes throughout development.

In the developing embryo of a fruit fly, Yan and Pnt are regulated by signals induced by a receptor called EGFR. When EGFR is activated, Pnt is produced and Yan is degraded. When this receptor is not activated, Yan is produced and represses Pnt. Mathematical modelling of these interactions has concluded that this is a bistable system: that is, cells should either have high levels of Yan and low levels Pnt, or low Yan levels and high Pnt levels. However, larval eye cells first activate, and then turn off, both proteins together. This argues against bistability and raises questions about how these proteins regulate cell fate transitions in the eye, and perhaps in other organs.

To investigate this question, Peláez et al. tagged Yan with a fluorescent marker to track its activity in the eyes of fruit fly larvae as they develop. A combination of fluorescence-based microscopy and an automated imaging analysis system were then used to score fluorescence in thousands of individual eye cells and assess the changes in the levels of Yan over time. This approach revealed some unexpected results.

Yan levels were seen to vary in both immature and maturing cells. Thus eye cells transition between states as Yan levels increase rapidly, suggesting the need for a mechanism that is distinct from bistability. Peláez et al. suggest that larger changes in the seemingly random fluctuations in the levels of the transcription factor (also known as “expression noise”) might play a role in this mechanism. In particular, Yan expression noise briefly peaks as cells transition to a more mature state, and the transient nature of this ‘noisy’ response requires the activation of EGFR.

One possible explanation for these observations is that Yan’s effect on cell states depends on this variability in its levels, which might prime cells to change states when they receive another signal. These findings also raise many questions for future studies to explore, including how this increase in the noise level of Yan is triggered as cells begin their transitions towards specific cell types.


Cells within complex organisms exist in different states that confer specific functionalities to each cell. Cellular states can be organized into cyclic cascades such as the G1-S-G2-M cell cycle, or into linear cascades as observed in cell differentiation. A common feature of cells that undergo state transitions is the apparent irreversibility of the transitions even when such transitions are triggered by transient stimuli. Modeling of these transitions often assumes system bistability, in which cells can be resting in one of two stable states.

Animal cells frequently utilize transcription factors to enforce a given state, and transitions to another state are driven by increasing or decreasing the levels of these transcription factors (Yao et al., 2008;Kueh et al., 2013; Laslo et al., 2006; Park et al., 2012). The Rb-E2F pathway generates bistability in E2F expression, which dictates the transition from G1 to S phase (Yao et al., 2008). Expression of the transcription factor PU.1 determines lymphoid versus myeloid hematopoietic cell lineages (Kueh et al., 2013; Laslo et al., 2006). Adipocyte differentiation is controlled by differential expression of C/EBP and PPARγ proteins (Park et al., 2012). Regulation by positive feedback is a hallmark of bistable systems, and in all of the above cases, the transcription factors act in one or more positive feedback circuits. In some systems, positive feedback is generated by two transcription factors that mutually repress each other’s expression. In these scenarios, cells in one state continually express a transcription factor that represses a second transcription factor, and when these cells transit to another state, they continually express the second transcription factor, which represses its antagonist. Fate restriction in hematopoietic, neural, pancreatic, and muscle cell lineages is regulated by such double-negative feedback circuits (Briscoe et al., 2000; Laslo et al., 2006; Olguin et al., 2007; Schaffer et al., 2010).

Most examples of this type of bistable mechanism have transcription factors that act specifically within a handful of cell states limited to a single tissue or organ system. One remarkable exception to this rule is found in Drosophila. There, two ETS-domain transcription factors act in a wide assortment of cell types across the body and across the life cycle. Yan and Pointed (Pnt) act downstream of signals mediated by receptor tyrosine kinases (RTKs) that regulate cell differentiation, migration, and division in tissues ranging from ovarian follicular cells, dorsal and ventral neuroectoderm, embryonic mesoderm, the embryonic trachea, and the post-embryonic compound eye (Dumstrei et al., 1998;Gabay et al., 1996; Halfon et al., 2000; Jurgens et al., 1984; Morimoto et al., 1996; O’Neill et al., 1994; Ohshiro et al., 2002; Yao et al., 2008) It is thought that Yan and Pnt control such diverse cell states by acting in concert with tissue-specific transcription factors to regulate transcription of appropriate target genes. For instance, transcription of even-skipped occurs in mesoderm only if Yan/Pnt act in combination with Tinman and Twist proteins (Halfon et al., 2000), whereas transcription of prospero (pros) in the eye only occurs if Yan/Pnt act in combination with Lozenge, Sine Oculis, and Glass proteins (Hayashi et al., 2008; Xu et al., 2000).

Several tissues show mutually exclusive expression of Yan and Pnt, suggestive of cross-repression (Boisclair Lachance et al., 2014). The best characterized is the embryonic ventral ectoderm, where ventral-most cells express Pnt and more lateral cells express Yan (Gabay et al., 1996). This pattern is established by secretion of a ligand for the EGF Receptor (EGFR) from the ventral midline (Golembo et al., 1996). EGFR activation in nearby ventral cells induces the Ras-MAPK pathway to express Pnt and degrade Yan (Gabay et al., 1996; Melen et al., 2005). Cells with insufficient EGFR activation express Yan, which represses Pnt. Mathematical modeling has described this as a bistable system in which cells are either in a High Yan/Low Pnt state or a Low Yan/High Pnt state (Graham et al., 2010; Melen et al., 2005). Transition from one state to the other is ultrasensitive to the strength of EGFR activation (Melen et al., 2005).

Paradoxically, other Drosophila tissues show co-expression of Yan and Pnt (Boisclair Lachance et al., 2014). The larval eye is one such tissue. Retinal progenitor cells initiate expression of both proteins, and when they transit to differentiated photoreceptor fates, these cells reduce expression of both proteins. In contrast, when retinal progenitor cells transit to differentiated cone cell fates, they maintain their expression of both proteins. These observations are at odds with long-standing genetic studies that support a standard bistable mechanism acting in the eye (Lai and Rubin, 1992;O’Neill et al., 1994; Rebay and Rubin, 1995). Thus, new approaches to studying these transitions in the eye are needed.

Here, we have adopted a systems-level approach to study Yan dynamics in the larval eye. A yellow fluorescent protein (YFP) — based isoform of Yan was developed as a reporter for Yan protein levels. Fluorescence-based microscopic imaging of cells was coupled with automated high-throughput image analysis to score fluorescence in each cell and annotate the data in a quantitative and unbiased fashion. Yan exhibits monostability, both in progenitor and differentiating cells, with Yan levels varying in cells in either state. Cell state transitions occur independent of absolute Yan concentrations, suggesting that some other mechanism allows Yan to regulate transitions. One such mechanism might be the noise in Yan levels, which undergoes a transient spike as cells begin to transition to differentiated states. Loss of EGFR signaling, which prevents cells from differentiating, causes these cells to have prolonged noisy Yan expression, and suggests that Yan noise is key for cell state transitions in the eye.


The compound eye epithelium is established during embryogenesis as an internal disc of cells called the eye imaginal disc (Wolff and Ready, 1993). During the larval phase of the life cycle, the disc grows in size by asynchronous cell division. During the final 50 hr of the larval phase, a morphogenetic furrow (MF) moves across the eye disc from posterior to anterior (Figure 1A,B). All cells arrest in G1 phase within five cell diameters anterior to the furrow, and then as the furrow passes through them, periodic clusters of cells express the proneural gene atonal (Jarman et al., 1994). Atonal expression is subsequently restricted to one cell per cluster, which becomes the R8 photoreceptor. Each R8 cell then secretes an EGFR ligand that activates the receptor in neighboring cells and causes them to transit from multipotent progenitor to differentiated states (Figure 1C) (Freeman, 1996). Transitions occur in a sequence of symmetric pairs of multipotent progenitor cells that differentiate into R2/R5, R3/R4, and R1/R6 photoreceptors (Figure 1C) (Wolff and Ready, 1993). Thereafter, a single progenitor transits to a R7 photoreceptor fate followed by two pairs of cells, C1/C2 and C3/C4, that differentiate into cone cells. These cone cells are non-neuronal and form the simple lens that overlies each cluster of eight photoreceptors. The furrow induces the nearly simultaneous differentiation of a column of R8 cells, with repeated column inductions producing approximately 800 units or ommatidia as the furrow moves across the eye.

Figure 1.Development and patterning of the compound eye.

(A) Differentiation is initiated in the developing eye by the MF, which moves across the eye epithelium. On the furrow’s posterior side, G1-arrested progenitor cells undergo differentiation (light blue). On the anterior side, progenitor cells are still proliferating (dark blue). The large grey rectangle outlines the region that was analyzed for Yan levels; the small rectangle corresponds to the developmental sequence outlined in panel C (B) A maximal projection of Yan-YFP fluorescence in an eye. Bar = 100 μm. (C) Top, an apical view of the sequential differentiation of eight photoreceptor (R1-R8) and four cone cell types (C1-C4) from multipotent progenitor cells (grey) in an ommatidium. Arrows denote inductive signal transmitted from the R8 to activate EGFR on nearby cells. Bottom, a cross-section view through an eye disc adapted after Wolff and Ready (1993). Note the progenitor cell nuclei are basally positioned, and as they transition into a differentiated state, their nuclei migrate apically. C1/C2 cells are positioned anterior and posterior in the ommatidium while C3/C4 cells are positioned equatorial and polar in the ommatidium. (D) Top, an optical slice of H2Av-mRFP fluorescence in an eye disc at a plane that bisects progenitor cell nuclei. Bottom, the same optical slice imaged for Yan-YFP fluorescence. Bars = 8 μm

A central tenet of the bistable model of cell differentiation in the eye posits that differentiation is marked by a transition from high Yan protein levels in multipotent progenitor cells to low Yan levels in differentiating cells (Graham et al., 2010). Formulation of this model stemmed from studies of R7 cell differentiation, the final photoreceptor recruited to each ommatidium. Reduced Yan causes inappropriate expression of the R7 determinant pros and ectopic R7 cells in yan hypomorphic mutants (Kauffmann et al., 1996; Lai and Rubin, 1992). Conversely, a Yan isoform that is resistant to MAPK-dependent degradation, blocks R7 differentiation and pros expression (Kauffmann et al., 1996; Rebay and Rubin, 1995).

Quantifying Yan dynamics

To quantitatively test the bistable model, we used BAC recombineering to insert fast-fold yellow fluorescent protein (YFP) in-frame at the carboxy-terminus of the yan coding sequence (Webber et al., 2013). The Yan-YFP transgene fully complemented null mutations in the endogenous yan gene and completely restored normal eye development (Figure 1—figure supplement 1), demonstrating that the YFP tag does not compromise Yan function and that all essential genomic regulatory sequences are included. The pattern of Yan-YFP protein expression was qualitatively similar to that of endogenous Yan (Figure 1—figure supplement 1).

We used histone His2Av-mRFP fluorescence in fixed specimens to mark all eye cell nuclei for automated segmentation (Figure 1D—figure supplement 2). Nuclei were manually classified into the different cell types of the eye, which is possible because every cell undergoing differentiation can be unambiguously identified by its position and nuclear morphology without the need of cell-specific markers (Ready et al., 1976; Tomlinson, 1985; Tomlinson and Ready, 1987; Wolff and Ready, 1993). To validate our identification of all cell types using this method, we cross-checked with specific cell-specific markers, and found that our classification was accurate over 98% of the time (Figure 1—figure supplement 3). Cells were scored for nuclear Yan-YFP concentration and their exact position within 3D coordinate space of each fixed eye sample (Figure 1—figure supplement 2). Yan-YFP protein levels were normalized to His2Av-mRFP, which provided some control over measurement variation (Figure 1—figure supplement 4). We then mapped each cell’s spatial position in the x-y plane of the eye disc onto time. Two reasons made this possible. First, the furrow moves at an approximately constant velocity forming one column of R8 cells every two hours (Basler and Hafen, 1989; Campos-Ortega and Hofbauer, 1977). Second, each column of R8 cells induces the other cell fates at a constant rate (Lebovitz and Ready, 1986). Thus even in a fixed specimen, the temporal dynamics of cell state transitions are visible in the repetitive physical organization of ommatidia relative to the furrow (Figure 1C). Together these features allow the estimation of time based on a cell’s position relative to the furrow (Figure 2—figure supplement 1). This can be applied repeatedly to hundreds of cells in a single sample, creating a composite picture of the dynamics (Figure 2B–F). Although the developmental progression of an individual cell cannot be measured by this approach, it nevertheless provides a dynamic view of hundreds of cells across a developing epithelium as they respond to signaling processes. From this information, individual cell behaviors can be reconstructed and modeled.


Figure 2.Dynamics of Yan-YFP in eye cells.

(A) Average time at which initiation of differentiation is first detected by apical migration of committing cell nuclei. Time zero is set to when R8 differentiation initiates. Differentiation proceeds over a time course after commitment is initiated (horizontal arrows) (B) Yan-YFP fluorescence in multipotent progenitor cells. We fit a Hill function (blue curve) to the inductive phase and an exponential decay (black curve) to the decay phase. (C-F) Scatter plots of Yan-YFP levels in individual cells for R2/R5 (C), R3/R4 (D), R7 (E), and C3/C4 (F) cells. These are overlaid with scatter plots of Yan-YFP in multipotent cells at times preceding and coincident with the appearance of the relevant differentiated cells. Note the similar Yan-YFP levels between multipotent cells and differentiating cells at their first appearance. (G) Moving averages of Yan-YFP levels for multipotent and photoreceptor cells. Gaps between the multipotent and photoreceptor curves are due to the window size for line averaging. (H) Moving averages of Yan-YFP in multipotent and cone cells.

Yan-YFP expression in multipotent progentior cells was biphasic (Figure 2B). Cells anterior to the furrow expressed a basal level of Yan-YFP, but this level dramatically increased in cells immediately anterior to the furrow, starting eight hours before the first R8 cells were identifiable. Approximately eight hours after R8 definition, Yan-YFP levels peaked, and thereafter gradually decayed until Yan-YFP approached its basal level again. The results are surprising in two ways. First, Yan-YFP is not maintained at a stable steady state within progenitor cells, which would have been predicted by the bistable model. Rather, its dynamics are reminiscent of monostable responses to transient stimuli, with a single basal steady state. Second, at the peak of Yan-YFP expression, there is remarkably large heterogeneity in Yan-YFP levels across cells.

We also followed Yan-YFP dynamics in cells as they transited into a differentiated state and thereafter. Again, the results did not follow the expectations predicted by the bistable model. First, progenitors transited to a differentiated state at levels of Yan-YFP that varied, depending upon the type of differentiated state being adopted (Figure 2C–H). Cells entering the R3/R4 and R1/R6 states began with Yan-YFP levels that were approximately two-fold greater than cells entering the R2/R5 states. Cells entering the R7 state were intermediate between these two extremes. Despite these differences at the transition point, Yan-YFP levels decayed to a similar basal steady state irrespective of the photoreceptor type, and this basal level was at least three-fold lower than that which the progenitor cells achieved (Figure 2G). Thus, rather than the single high Yan progenitor state previously modeled, our results suggest a dynamic range of high Yan states from which different cell fates are specified according to the spatio-temporal sequence of differentiation.

We noted that for most photoreceptors, it took approximately 20 hr for Yan-YFP to decay to the basal steady state (Figure 2G), significantly longer than had been previously modeled (Graham et al., 2010). Since expression of several neural-specific genes is detected 2–8 hr after the transition (Tomlinson and Ready, 1987; Van Vactor et al., 1988), the slower than anticipated Yan decay indicates that early differentiation does not require cells to have assumed a basal steady-state level of Yan-YFP.

The last group of progenitors to differentiate form the non-neuronal cone cells. We also measured Yan-YFP in those cells. Yan-YFP dynamics in cone cells were more similar to progenitor cells over the same time period (Figure 2F,H). This behavior was in contrast to photoreceptors, which exhibited different decay dynamics from progenitor cells. Thus, accelerated degradation of Yan-YFP is not essential for cells to transition to all retinal cell states.

EGFR-ras signaling regulates Yan-YFP dynamics

The bistable model posits that the switch from one state to another is triggered by a signal that progenitor cells receive though the EGFR protein. Given the unanticipated Yan-YFP dynamics, we wanted to ask whether and how they were influenced by EGFR signaling. EGFR null mutants are inviable; however, a temperature sensitive (ts) allele of EGFR enables controlled inactivation of the RTK’s activity (Kumar et al., 1998). We grew EGFRts mutant larvae at a restrictive temperature for 18 hr before analyzing effects on Yan-YFP. Surprisingly, progenitor cells exhibited biphasic expression of Yan-YFP over time, but the amplitude of the pulse in expression was significantly reduced (Figure 3A). This suggests that EGFR signaling contributes to the stimuli that induce the Yan-YFP peak. To further test this hypothesis, we misexpressed a constitutively active form of Ras protein in eye cells. The peak of Yan-YFP in progenitors was now prolonged (Figure 3B). Together, these results suggest that EGFR-Ras signaling stimulates the transient appearance of Yan-YFP in progenitor cells, and that the decline in Yan-YFP within older progenitor cells is linked to a loss of signal reception by these cells over time.


Figure 3.EGFR/Ras and Pnt regulate Yan-YFP levels.

(A–D) Moving averages of Yan-YFP in different cell types. Shown with shading is the standard error of the mean for each moving average. (A,C) Wildtype and EGFRts mutants incubated at the non-permissive temperature and analyzed for progenitors (A) and R2/R5 cells (C). (B,D) Wildtype and sev>Rasv12 mutants were analyzed for progenitors (B) and R2/R5 cells (D). (E) Optical slice through progenitor cell nuclei in a disc that contains clones ofpnt2 mutant cells. Left, fluorescence of RFP, which positively marks wildtype cells and not pnt2 mutant cells. Middle, Yan-YFP fluorescence, showing reduced levels in pnt2mutant clones. Arrows highlight apoptotic nuclei. Right, merged image with Yan-YFP in green and RFP in purple. Clone borders are outlined. (F,G) Moving averages of Yan-YFP in R3/R4 cells that ectopically express PntP1 (F) or PntP2-VP16 (G) due to LongGMR-Gal4 driving the UAS transgenes. Since PntP2 requires MAPK phosphorylation to become transcriptionally active, we misexpressed a VP16 fusion of PntP2. PntP1 is constitutively active (Brunner et al., 1994Gabay et al., 1996).

We next examined the effects of EGFR and Ras on Yan-YFP dynamics in cells as they differentiate. The bistable model predicts that EGFR is required for the loss of Yan-YFP in photoreceptors. Indeed,EGFRts mutant R2/R5 cells delayed their initial decline in Yan-YFP levels (Figure 3C). Conversely, misexpression of constitutively active Ras caused a premature decline in Yan-YFP (Figure 3D). These results are consistent with EGFR-Ras stimulating the degradation of Yan-YFP as cells switch their states. However, Yan-YFP dropped to below-normal levels in EGFRts mutant R2/R5 cells (Figure 3C). These complex effects suggest a dual role for EGFR signaling in photoreceptors. In the first few hours as cells transit to a photoreceptor state, EGFR stimulates the accelerated decay of Yan-YFP. Thereafter, EGFR inhibits the decay of Yan-YFP in a manner that might be related to that role that EGFR plays in boosting Yan-YFP levels in progenitor cells.

The source of EGFR ligand originates from the R8 cell (Freeman, 1996). If this diffusive ligand is responsible for controlling Yan-YFP levels in other photoreceptors as they are recruited to an ommatidium, we would predict a correlation between Yan-YFP levels in differentiating cells and their distances from adjacent R8 cells. Indeed, at the times when R2/R5 cells differentiate (~0–15 hr), their Yan-YFP levels are positively correlated (p<0.01) with their physical distance to the nearest R8 cells (Figure 3—figure supplement 1). These correlations are absent in EGFRts mutants, providing evidence that R8 cells act through EGFR to control Yan-YFP dynamics in differentiating cells.

Pnt regulates Yan dynamics

Pnt proteins have been hypothesized to cross-repress Yan expression, and this double negative feedback loop is thought to be necessary for bistability (Graham et al., 2010; Shilo, 2014). At odds with this view, Pnt and Yan proteins are co-expressed in progenitor and differentiating cells of the eye (Boisclair Lachance et al., 2014). Since Pnt proteins act downstream of many RTKs including EGFR, we wondered if Pnt mediated the positive effects of EGFR-Ras signaling on Yan-YFP in progenitor cells. Null mutants of the pnt gene are embryonic inviable; therefore we generated clones of eye cells that were null mutant for pnt in an otherwise wildtype animal. Mutant progenitor cells showed a reduction in Yan-YFP levels as they progressed through their biphasic expression pattern (Figure 3E). Thus, Pnt possibly mediates the positive effect of EGFR signaling on Yan-YFP expression in progenitors. We also wished to know if Pnt mediates the complex effects of EGFR in differentiating photoreceptors. Pnt proteins are rapidly cleared in photoreceptors (Boisclair Lachance et al., 2014) and so loss-of-function mutant analysis would be uninformative. Therefore, we overexpressed PntP1 or constitutively-active PntP2 in cells as they transited into a photoreceptor state and beyond. The early phase of Yan-YFP decay was accelerated while the later phase of Yan-YFP decay was inhibited (Figure 3F,G). These complex effects are precisely the opposite to those caused by loss of EGFR signaling, as would be expected if Pnt mediated EGFR’s complex effects on Yan-YFP dynamics in photoreceptor cells.

Cells are indifferent to absolute levels of Yan

The bistable model predicts that different cell states depend upon discrete absolute concentration of Yan present inside cells. To test this idea, we varied the number of Yan-YFP gene copies. In general, protein output is proportional to gene copy number in Drosophila (Lucchesi and Rawls, 1973). We increased Yan-YFP copy number from its normal diploid number to tetraploid, and monitored Yan-YFP in progenitors and differentiating cells. As expected, four copies caused a higher steady-state level of Yan-YFP in progenitor cells, though this increase was less than two-fold (Figure 4A). The amplitude of the Yan-YFP pulse was also increased as progenitor cells aged. Strikingly, as four-copy progenitor cells transited to a differentiated state, the onset of Yan-YFP decay occurred at the same time as it occurred for two-copy cells (Figure 4A–C). Yan-YFP levels were much greater in four-copy cells compared to two-copy cells making their transit into the identical cell states. To confirm that absolute Yan-YFP concentration had little effect on cell state transitions, we examined expression of a direct target of Yan in R7 cells: the pros gene (Kauffmann et al., 1996; Xu et al., 2000). Expression was monitored with an antibody specific for Pros protein. We observed at most a one hour delay in the onset of Pros expression in R7 cells containing four copies of Yan-YFP (Figure 4D), far less than the ten-hour delay predicted if absolute concentration of Yan-YFP dictated when Pros expression begins (Figure 4D).

Figure 4.Cell state transitions are unaffected by Yan-YFP gene copy number.

(A–C) Moving averages of Yan-YFP in eye discs containing two versus four copies of the Yan-YFP transgene. (A) R2/R5 and progenitor cells. (B) R3/R4 and progenitor cells. (C) R7 and progenitor cells. (D) Moving averages of Yan-YFP and Pros proteins in R7 cells containing either two vs. four copies of the Yan-YFP transgene.

Possibly, absolute concentration of Yan is unimportant when a cell transits to a different state, but the switch to a constant basal Yan level is robustly maintained regardless of starting concentration. An examination of Yan-YFP decay in photoreceptor cells makes that possibility less likely; Yan-YFP decays to different basal levels in two- versus four-copy differentiated cells (Figure 4A–C). To further test this notion, we fit the data to several plausible functional forms. We found that exponentially decaying functions systematically best-fit to the data (Figure 4—figure supplement 1). Thus, for each cell state we fit an exponential decay function to its Yan-YFP temporal profile (Figure 4—figure supplement 2). From these fits, we derived the average decay rate constants and half-lives of Yan-YFP for cells carrying two, four, or six copies of yan. As expected, we found that Yan-YFP half-life was different between progenitors and differentiating photoreceptors (Figure 5—figure supplement 1). The half-life in photoreceptors was two-fold lower than in progenitors, accounting for the more rapid loss of Yan-YFP in the former cells. Strikingly, Yan-YFP half-life was not significantly affected byyan copy number within either progenitor or photoreceptor cells (Figure 5). Thus, Yan-YFP concentration only affected its decay rate as a first-order function, implying that there is no higher order mechanism to accelerate Yan-YFP decay when cells contain greater concentrations of Yan-YFP.


Figure 5.Yan protein half-life is largely unaffected by yan gene copy number.

Exponential decay of Yan-YFP levels. Note the robustness of Yan-YFP half-lives across replicates and yan gene copy number. Note also how half-lives are nearly twice as long for progenitor cells versus photoreceptor neurons.

As a final test of the effects of Yan-YFP levels on cell states, we allowed 4X and 6X yan animals to complete eye development and then examined the external patterning of the fully differentiated compound eye. The compound eyes were completely normal in appearance (Figure 5—figure supplement 2), implying that differentiation was unaffected by the absolute concentrations of Yan inside eye cells.

Yan expression noise spikes during cell state transitions

Our results indicate that Yan’s effects on retinal cell states are not dictated by uniform and stable concentrations of Yan protein. One potential explanation is that Yan’s effect on cell states actually depends on variability in Yan protein levels. A growing body of evidence is pointing to the importance of transient fluctuations in expression of factors to control cell states (Cahan and Daley, 2013;Torres-Padilla and Chambers, 2014). Key regulators of stem cells fluctuate in abundance over time, and this is correlated with stem cells existing in multiple connected microstates, with the overall structure of the population remaining in a stable pluripotent macrostate (MacArthur and Lemischka, 2013). Heterogeneity among cells is not simply due to independent noise in expression of individual genes but is due to fluctuating networks of regulatory genes (Chang et al., 2008; Kumar et al., 2014). Such fluctuations appear to be stochastic in nature, priming cells to transit into differentiated states with a certain probability that is guided by extrinsic signals.

Our data revealed considerable heterogeneity in the level of Yan-YFP among cells at similar developmental times (Figure 2B). To quantify the noise, we used developmental time to bin cells of similar age, and measured detrended fluctuations of Yan-YFP by calculating residuals to the fitted function and normalizing binned residuals to the function (Goldberger et al., 2002). Progenitor cells showed a spike in Yan-YFP noise as they began to induce Yan-YFP expression (Figure 6A). The noise spike was short-lived (approximately 17 hr), and noise thereafter returned to a basal level with secondary minor spikes. The major peak in noise magnitude coincided with the time at which R8 cells are formed.

Figure 6. Noise in Yan-YFP expression is highly dynamic.

Moving averages of Yan-YFP levels and noise (detrended fluctuations) for (A) progenitors, (B) R2/R5, (C) R3/R4, (D) R1/R6, and (E) R7 cells. (F) Comparative noise dynamics for all cells analyzed in (AE). (G) Moving averages of Yan-YFP noise (coefficient of variation) in R2/R5 cells sampled from wildtype and EGFRts mutant eyes at the non-permissive temperature. Shown with shading is the standard error of the mean for each moving average. (H) Moving averages of Yan-YFP noise (coefficient of variation) in R2/R5 cells sampled from wildtype and sev>Rasv12 mutant eyes. Shown with shading is the standard error of the mean for each moving average.

Photoreceptor cells showed a large spike in Yan-YFP noise as they began to differentiate (Figure 6B–E). The magnitude of each noise peak varied with the photoreceptor cell state; R3 and R4 cells exhibited the greatest amplitude in noise (Figure 6F). These noise spikes showed a distinct temporal relationship, with spikes coinciding with the times at which individual cell states were switched (Figure 6F). Thus, the noise spikes are not a simple consequence of a global stimulus synchronously affecting noise in all cells. Thereafter, all cells reduced Yan-YFP noise to a basal level that was comparable to basal noise in the progenitor cells. However, each cell type exhibited a secondary minor spike at 30–35 hr, which might reflect a synchronous stimulus.

Detrended fluctuation is one method to measure expression variability, but it can suffer from distortion if the model fitting is not adequately weighted. Therefore, we also calculated the coefficient of variation, that is, the standard deviation of Yan-YFP intensity within a sliding window divided by its mean. This method yielded noise profiles with transient spikes for each cell type that was consistent with calculations using detrended fluctuation (Figure 6—figure supplements 1 and 2). However, while the coefficient of variation yielded results that varied strongly with bin width, the detrended fluctuations yielded profiles that were generally robust against changes in bin width (Figure 6—figure supplement 1).

To rule out the possibility that these unexpectedly dynamic features of Yan-YFP were caused by its transgenic origins or fusion with YFP, we compared Yan-YFP dynamics to those of endogenous Yan protein that was bound with an anti-Yan antibody. The profiles of Yan-YFP protein levels and noise were highly similar to endogenous Yan protein levels and noise, in both multipotent and differentiating cells (Figure 6—figure supplement 3). Thus, transient spikes of expression heterogeneity are a fundamental feature of Yan protein.

Since Yan regulates Pros expression in R7 cells, it was possible that Pros showed a transient noise spike as a consequence. Therefore, we measured Pros protein heterogeneity and found that its dynamics did not resemble that of Yan (Figure 6—figure supplement 4). Instead, Pros noise was high starting at the onset of expression, and thereafter gradually declined as Pros protein levels increased in R7 cells. We conclude that noise spikes are not a general feature of gene expression in the developing eye but might reflect unique roles of Yan in mediating cell state transitions.

We wondered what might cause these spikes in Yan-YFP noise during cell state transitions. Because EGFR signaling is important for regulating Yan-YFP concentration during these transitions (Figure 3), we analyzed Yan-YFP noise when EGFR signaling was inhibited in EGFRts mutant animals raised at a non-permissive temperature. The noise spike in progenitor cells was not significantly affected by loss of EGFR signaling (data not shown). We also examined the effects of EGFRts on noise in differentiating photoreceptor cells. Interestingly, noise increased at the normal time of transition but the elevated noise did not quickly drop to basal levels (Figure 6G). Rather, high noise was extended for an additional 10 to 15 hr. Conversely, misexpressing constitutively active Ras within differentiating cells caused a premature dropdown in Yan-YFP noise (Figure 6H). These results indicate that EGFR/Ras signaling is required for the rapid drop in Yan-YFP noise after it has peaked, creating a transient spike.


This study relied upon a set of methods that enable systems-level analysis of Yan expression dynamics in a developing animal tissue. Transgene recombineering was used to insert YFP into a genomic rescue fragment of the yan gene, which fully replaced endogenous yan. Yan-YFP protein was quantified in thousands of individual cells by fluorescence confocal microscopy and automated cell segmentation analysis. Based on the unique features of Drosophila eye development, every analyzed cell was assigned an age, and composites of cells across a time-spectrum of ages were derived. This allowed us to reconstruct the temporal dynamics of Yan protein expression in cells as they transited from one state to another or were maintained in a given state. The fact that both Yan concentration and noise were easily measured using our approach indicates that it provides a powerful method for studying how other molecular determinants regulate cell states.

Contrary to what is currently believed, the expression of Yan in progenitor cells has many hallmarks of monostability. A stable basal state exists in cells anterior to the furrow, and when the furrow passes, Yan rises and falls to form a biphasic profile (Figure 7A). If cells transit towards differentiation, then the fall in Yan is accelerated but the fundamental biphasic profile is preserved. This monostable-like behavior is not like a behavior where progenitor cells exist in a high Yan stable-state and switch to a low Yan stable-state when they transit towards differentiation (Figure 7A). Other lines of evidence also point away from a bistable switch mechanism. Yan reaches its basal steady state many hours after cells have adopted their differentiated photoreceptor state and are executing specialized gene expression programs. Thus, Yan levels are variable at the time when cells actually become differentiated.

 Figure 7.


Figure 7.Summary of analysis.

(A) Top: a hypothetical bistable behavior would be where Yan is in a stable high state within progenitor cells and in a stable low state within differentiated cells. Bottom: the observed behavior of Yan appears monostable, with both progenitors and differentiated cells in unstable Yan states. (B) Heterogeneity in Yan expression is maximal when progenitor cells enter a transition state that resolves to a more homogeneous differentiated state, dependent upon EGFR signaling. This heterogeneous transition state may be a primary mechanism for Yan’s effect on cells, independent of the absolute Yan concentration within progenitors.

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Illuminating a Cancer’s Origins

Researchers have developed a technique to visualize the origin of melanoma in zebrafish, throwing light on a genetic switch for cancer.

By Catherine Offord | February 1, 2016

Many cells containing cancer-associated genes never become tumors. Using a fluorescent reporter to highlight cells activating stem cell-like patterns of gene expression, researchers at Boston Children’s Hospital have now developed a technique to visualize the origins of tumors in zebrafish. The team’s findings were published last week (January 29) in Science.

“An important mystery has been why some cells in the body already have mutations seen in cancer, but do not yet fully behave like the cancer,” Charles Kaufman of Boston Children’s Hospital said in a statement. “We found that the beginning of cancer occurs after activation of an oncogene or loss of a tumor suppressor, and involves a change that takes a single cell back to a stem cell state.”

The researchers focused on a gene present in vertebrates called crestin. This gene is expressed normally only in neural crest progenitor cells, which give rise to a number of other cell types during embryogenesis. However the gene is also expressed in melanoma tumor cells, making it a clear marker of the onset of cancer.

Injecting a fluorescent crestin reporter into transparent zebrafish carrying mutations in melanoma genes, the researchers found they were able to visualize the moment that precancerous cells activated stem cell-like patterns of gene expression.

“Every so often we would see a green spot on a fish,” said study coauthor Leonard Zon of Boston Children’s Hospital in the statement. “When we followed them, they became tumors 100 percent of the time.”

“It’s a significant advance in the field,” Ze’ev Ronai, the scientific director of the Sanford Burnham Prebys Medical Discovery Institute in La Jolla, California, told The New York Times. “They provide a pretty strong demonstration that that pathway is correct.”

The team will now focus on the pathways regulating the switch in gene expression, according to the statement—research that Kornelia Polyak of the Dana-Farber Cancer Institute told the Times would be essential to develop drugs targeting melanoma.

“What is the stimulus that allows a single cell out of millions to become cancerous?” she asked. “What is the trigger and why does it happen so rarely? Why, why is this happening?”

Fluorescence, nucleic acid strands help show computing operations inside a living cell

Using strands of nucleic acid and a fluorescence reporter, scientists at the Georgia Institute of Technology (Georgia Tech; Atlanta, GA) and colleagues have demonstrated basic computing operations inside a living mammalian cell. The research could lead to an artificial sensing system that could control a cell’s behavior in response to such stimuli as the presence of toxins or the development of cancer.

Related: Non-damaging, light-emitting nanoprobes enable long-term study of living cells

The research uses DNA strand displacement, a technology that has been widely used outside of cells for the design of molecular circuits, motors, and sensors. Researchers modified the process to provide both “AND” and “OR” logic gates able to operate inside the living cells and interact with native messenger RNA (mRNA).

The tools they developed could provide a foundation for biocomputers able to sense, analyze, and modulate molecular information at the cellular level. Philip Santangelo, an associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, says the devices could sense an aberrant RNA, for instance, and then shut down cellular translation or induce cell death.

Strand displacement reactions are the biological equivalent of the switches or gates that form the foundation for silicon-based computing. They can be programmed to turn on or off in response to an external stimuli such as a molecule. An “AND” gate, for example, would switch when both conditions were met, while an “OR” gate would switch when either condition was met.

In the switches the researchers used, a fluorescence reporter molecule and its complementary quenching molecule were placed side-by-side to create an “off” mode. Binding of RNA in one of the strands then displaced a portion of nucleic acid, separating the molecules and allowing generation of a signal that created an “on” mode. Two “on” modes on adjacent nucleic acid strands created an “AND” gate.


Image shows activation of “AND” gates in cells as observed by fluorescence microscopy. (Credit: Chiara Zurla, Georgia Tech)

Georg Seelig, assistant professor of computer science and engineering and electrical engineering at the University of Washington, says that in the longer term, the research team wants to expand this technology to create circuits with many inputs, such as those they have constructed in cell-free settings.

The researchers used ligands designed to bind to specific portions of the nucleic acid strands, which can be created as desired and produced by commercial suppliers.

Challenges in the research team’s work were getting the devices into the cells without triggering the switches, providing operation rapid enough to be useful and not killing the human cell lines that the researchers used in the lab.

The nucleic acid computers ultimately operated as desired, and the next step is to use their switching to trigger the production of signaling chemicals that would prompt the desired reaction from the cells. Cellular activity is normally controlled by the production of proteins, so the nucleic acid switches will have to be given the ability to produce enough signaling molecules to induce a change.

Cells, of course, already know how to sense toxic molecules and the development malignant tendencies, and to then take action. But those safeguards can be turned off by viruses or cancer cells that know how to circumvent natural cellular processes.

Full details of the work appear in the journal Nature Nanotechnology; for more information, please visit http://dx.doi.org/10.1038/nnano.2015.278.


Computing in mammalian cells with nucleic acid strand exchange

Benjamin GrovesYuan-Jyue ChenChiara Zurla, Sergii PochekailovJonathan L. KirschmanPhilip J. Santangelo & Georg Seelig

Nature Nanotechnology(2015)    http://dx.doi.org:/10.1038/nnano.2015.278

DNA strand displacement has been widely used for the design of molecular circuits, motors, and sensors in cell-free settings. Recently, it has been shown that this technology can also operate in biological environments, but capabilities remain limited. Here, we look to adapt strand displacement and exchange reactions to mammalian cells and report DNA circuitry that can directly interact with a native mRNA. We began by optimizing the cellular performance of fluorescent reporters based on four-way strand exchange reactions and identified robust design principles by systematically varying the molecular structure, chemistry and delivery method. Next, we developed and tested AND and OR logic gates based on four-way strand exchange, demonstrating the feasibility of multi-input logic. Finally, we established that functional siRNA could be activated through strand exchange, and used native mRNA as programmable scaffolds for co-localizing gates and visualizing their operation with subcellular resolution.

Subject terms:  DNA computingRNA nanotechnology

Figure 1: Empirical design parameters determine in-cell performance.close

Empirical design parameters determine in-cell performance.

Decisions made at the design level, such as the choice of gate architecture, nucleic acid modifications and delivery method have a strong impact on reaction kinetics, stability against nuclease degradation and subcellular localization..


aurelianu2007 commented on Single Cell Shines Light on Cell Malignant Transformation

Single Cell Shines Light on Cell Malignant Transformation Larry H. Bernstein, MD, FCAP, Curator LPBI Single Cell …

The lack of oxygen inhibits the transport of protons and thereby causes a decrease in membrane potential. Cell survival under conditions of mild hypoxia is mediated by phosphoinositide-3 kinase (PIK3) using severe hypoxia or anoxia, and then cells initiate a
cascade of events that lead to apoptosis. After DNA damage, a very important regulator of apoptosis is the p53 protein. This tumor suppressor gene has mutations in over 60% of human tumors and acts as a suppressor of cell division. The growth-suppressive effects of p53 are considered to be mediated through the transcriptional trans-activation activity of the protein. In addition to the maturational state of the clonal tumor, the prognosis of patients with CLL is dependent of genetic changes within the neoplastic cell population.
The genetic changes can be identified by fluorescent probes to chromosomal using a technique referred to as fluorescent in situ hybridization (FISH). Chromosomal evaluation using FISH can identify certain chromosomal abnormalities of CLL that have prognostic significance. Deletion of part of the short arm of chromosome 17 (del 17 q), with target the cell cycle regulating protein p53, is particularly deleterious. This abnormality is found in 10% of patients with CCL and has a pour
prognosis. Deletion of long arm of chromosome 13(del 13q) is the most common geneticabnormality in CLL with roughly 50% of patients exhibiting this effect. These patients have the best prognosis and most will live many years without the need for therapy. Agents damaging DNA may increase the expression of p53 and its trans-activation activity, suggesting that p53 acts to protect cells against the accumulation of mutants and their subsequent conversion to a malignant
Protein p53, in its normal form, acts in stopping the cell division whenever damage to a cell’s DNA is detected, thus giving the cells the possibility of repairing DNA before the errors would duplicate and be passed on to the daughter cells. Antibodies to human p53 have been detected in patients with cancer. These antibodies are highly specific for malignant diseases and are rarely detected in healthy donors or patients having benign diseases. This immune response is correlated with the presence of a p53 gene mutation, leading to the accumulation of an ineffectivep53 protein in tumor cells[ 8] with either tridimensional structure;Over-expression of normal p53 protein can result either in G1 arrest, mediated by p21 protein [ or in the induction of apoptosis [ 9 ]. Also hypoxia itself ca also prevent apoptosis by inducing the expression of the anti apoptotic protein IAP-2. A typical response to the hypoxic environment, by hypoxia inducible factor 1, [ 6] for example, is expression of insulin-independent GLUT [5] triggered by HIF 1α [6] insuring maximum glucose uptake for glycolytic ATP generation.


Mechanism of Tumor Suppressing Gene Uncovered

Published: Tuesday, January 26, 2016
Last Updated: Tuesday, January 26, 2016
The most commonly mutated gene in cancer,p53, works to prevent tumor formation by keeping mobile elements in check that otherwise lead to genomic instability, UT Southwestern Medical Center researchers have found.

The p53 gene long has been known to suppress tumor formation, but the mechanisms behind this function – and why disabling the gene allows tumors to form – were not fully understood.

Findings from the study answer some of these questions and could one day lead to new ways of diagnosing and treating cancer, said the study’s senior author, Dr. John Abrams, Professor of Cell Biology at UT Southwestern.

The investigators found that normal p53 gene action restrains transposons, mobile genetic elements called retroelements that can make copies of themselves and move to different positions on chromosomes. But, they discovered, when p53 is disabled by mutation, dramatic eruptions of these mobile elements occur. The study revealed that in mice with cancer and in human samples of two types of cancer (Wilms’ tumors and colon tumors) disabled for p53, transposons became very active.

In a healthy state, certain mechanisms work to keep these retroelements quiet and inactive, explained Dr. Abrams. One of those mechanisms is p53 action. Conversely, when p53 is mutated, retroelements can erupt.

“If you take the gene away, transposons can wreak havoc throughout the genome by causing it to become highly dysregulated, which can lead to disease,” Dr. Abrams said. “Our findings help explain why cancer genomes are so much more fluid and destabilized than normal genomes. They also provide a novel framework for understanding how normal cells become tumors.”

Although much more research is needed, Dr. Abrams said, the potential clinical implications of the team’s findings are significant.

“Understanding how p53 prevents tumors raises the prospect of therapeutic interventions to correct cases in which p53 is disabled,” Dr. Abrams said. “If retroelements are at the heart of certain p53-driven cancers, finding ways to suppress them could potentially allow us to prevent those cancers or intervene to keep them from progressing.”

This understanding also could lead to advances in diagnosing some cancers through biomarkers related to p53 and transposon activity.

“One possibility is that perhaps blood or urine tests could detect dysregulated retroelements that could be indicative of certain types of cancer,” Dr. Abrams said.

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cancer-hunting virus

Larry H. Bernstein, MD, FCAP, Curator



A ‘huge milestone’: approval of cancer-hunting virus signals new treatment era

Imlygic programs viruses to attack only cancer cells and gives patients more humane options – potentially ‘a complete change in the game’ in treatment


Microscopic view of pancreatic cancer cells


Microscopic view of pancreatic cancer cells. Photograph: Stocktrek Images, Inc. / Alamy S/Alamy Stock Photo


A new cancer treatment strategy is on the horizon that experts say could be a game-changer and spare patients the extreme side effects of existing options such as chemotherapy.

Chemotherapy and other current cancer treatments are brutal, scorched-earth affairs that work because cancer cells are slightly – but not much – more susceptible to the havoc they wreak than the rest of the body. Their side effects are legion, and in many cases horrifying – from hair loss and internal bleeding to chronic nausea and even death.

But last week the Food and Drug Administration (FDA) for the first time approved a single treatment that can intelligently target cancer cells while leaving healthy ones alone, and simultaneously stimulate the immune system to fight the cancer itself.

The treatment, which is called T-VEC (for talimogene laherparepvec) but will be sold under the brand name Imlygic, uses a modified virus to hunt cancer cells in what experts said was an important and significant step in the battle against the deadly disease.

It works by introducing a specially modified form of the herpes virus by injection directly into a tumour – specifically skin cancer, the indication for which the drug has been cleared for use.



The FDA is allowing the injectable drug Imlygic, made by Amgen Inc, to be used at first only on melanomas that cannot be removed surgically. The company said a single course would cost about $65,000 depending on the length of the treatment.

The drug is injected directly into tumour tissue, where it uses herpes as a Trojan horse to slip past and rupture cancer cells. The drug combines a gene snippet meant to stimulate the immune system with a modified version of the herpes simplex virus — the kind that causes mouth cold sores.

Despite the drug’s groundbreaking approach FDA officials stressed it had not been shown to extend life. Instead company studies showed that about 16% of patients injected with the drug saw their tumours shrink, compared with 2% of patients who took more conventional cancer drugs. That effect lasted at least six months.

Regulators stressed that Imlygic had no effect on melanoma that had spread to the brain, lungs or other internal organs.

Amgen said patients should be treated with the drug for at least six months, or until there were no more tumours left to treat.

The drug — known chemically as talimogene laherparepvec or T-VEC — divides into copies repeatedly until the membranes, or outer layers, of the cancer cells burst. Meanwhile the gene snippet produces a protein to stimulate an immune response to kill melanoma cells in the tumour and elsewhere in the body.

A 2013 review in the journal Molecular Cancer concluded that cancer-fighting viruses armed with genes that stimulate the immune system “are potent therapeutic cancer vaccines”.


It was developed by the Massachusetts-based biotech company BioVex, which was acquired in 2011 by biotech behemoth Amgen for $1bn. The genetic code of the virus – which was originally taken from the cold sore of a BioVex employee – has been modified so it can kill only cancer cells.

Cancer-hunting viruses have long been thought of as a potential source of a more humane and targeted treatment for cancer. Unlike current oncological treatments like chemotherapy and radiotherapy, which kill cancer cells but also damage the rest of the body, viruses can be programmed to attack only the cancer cells, leaving patients to suffer the equivalent of just a day or two’s flu.

Treatments such as Imlygic have two modes of action: first, the virus directly attacks the cancer cells; and second, it triggers the body’s immune system to attack the rogue cells too once it detects the virus’s presence.

Dr Stephen Russell, a researcher at the Mayo Clinic who specialises in oncolytic virotherapy – as these treatments are known – says that the FDA’s clearance of Imlygic represents “a huge milestone” in cancer treatment development.

Viruses are “nature’s last untapped bioresource”, Russell said. Imlygic itself has an officially fairly modest effect coming out of its clinical studies – an average lifespan increase of less than five months. But underneath that data, Russell said anecdotally that in his Mayo clinic studies in mice, some programmable viruses saw “large tumours completely disappearing”.

The goal, he said, was to get to the point where the clinical trials would see similarly dramatic outcomes, so that chemotherapy and radiotherapy could finally be consigned to medical history.

John Bell, a researcher into viral cancer therapies at the Ottawa Hospital Research Institute in Ottawa, Canada, said that while T-VEC was designed to be directly injected into a tumour – as opposed to being delivered to the whole body as a systemic treatment would be – the results showed systemic effects in some cases.

Some of the treatments use a modified version of measles, rather than herpes, as a vehicle. Both Russell and Bell pointed to a trial participant of Russell’s named Stacy Erholtz, whose incurable myeloma – blood cancer – disappeared, largely side effect free, in 36 hours after a treatment using a modified measles virus, an example of the kind of miraculous results that viral oncology researchers hope to replicate.

Of course, individual success stories like Erholtz’s are relatively meaningless without the hard data that come with replicable and repeated clinical trials. There are currently a number of similar treatments at the third stage of clinical testing – still several years of work behind Imlygic in terms of development – but progress is being made.

Russell is hopeful that Imlygic represents “a first step in the direction of a complete change in the game” in how we treat cancer. “We can’t prematurely claim that we’ve achieved our ultimate goal, because we haven’t; this really is a single step along that path,” he said. “But it’s a very important and very significant step.”


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Curator: Larry H. Bernstein, MD, FCAP


Nab-Paclitaxel Shows Benefit in Advanced Melanoma

News | October 01, 2015 | Melanoma
By Leah Lawrence
Treatment with nab­-paclitaxel resulted in significantly improved progression-free survival and a greater disease control rate in chemotherapy-naive patients with metastatic melanoma compared with dacarbazine, according to the results of a study published recently in Annals of Oncology.

Treatment with “nab-paclitaxel demonstrated clinically meaningful superiority compared with dacarbazine,” wrote Evan M. Hersh, MD, of the University of Arizona Cancer Center, and colleagues, “with a near doubling of median progression-free survival and a 44% improvement in disease control rate (includes patients with stable disease for ≥ 16 weeks) in chemotherapy-naive patients with metastatic melanoma.”

Based on these results, they concluded that “nab-paclitaxel can be considered in the treatment armamentarium for chemotherapy-naive patients with metastatic melanoma.”

According to the study, the use of taxanes in metastatic melanoma has had limited success; however, nab-paclitaxel—paclitaxel formulated as albumin-bound nanoparticles—has shown some efficacy in chemotherapy-naive patients.

This phase III trial randomly assigned 529 chemotherapy-naive patients with stage IV melanoma to nab-paclitaxel (n = 264) on days 1, 8, and 15, every 4 weeks, or dacarbazine (n = 265) every 3 weeks.

In the final analysis, 58% of patients assigned nab-paclitaxel and 64% assigned dacarbazine progressed or died. There was a greater than 2-month improvement in progression-free survival among patients assigned to nab-paclitaxel compared with dacarbazine (4.8 vs 2.5 months; hazard ratio [HR], 0.792 [95% confidence interval (CI), 0.631–0.992]; P=.004).

“The robustness of the progression-free survival analysis was supported with various sensitivity analyses related to off-schedule response assessments or missed study visits,” the researchers noted.

“The robustness of the progression-free survival analysis was supported with various sensitivity analyses related to off-schedule response assessments or missed study visits,” the researchers noted.

No significant difference in overall survival was seen between the two groups (12.6 vs 10.5 months; P = .271).

“Although a significant difference in progression-free survival was observed with nab-paclitaxel vs dacarbazine, a significant treatment effect of nab-paclitaxel on overall survival may have been limited by the equivalent and high rate (75%) of use of post-study therapy, including newer agents, such as BRAF inhibitors and ipilimumab, by patients in both treatment arms,” Hersh and colleagues wrote.

There was no significant difference in the overall response rate seen in patients assigned nab-paclitaxel (15%) compared with dacarbazine (11%). However, patients treated with nab-paclitaxel had significant improvements in disease control rate (P = .004) and best overall response rate (P = .002) compared with dacarbazine.

Subgroup analyses also found that nab-paclitaxel resulted in improvements in progression-free survival regardless of BRAF mutation status. In addition, nab-paclitaxel treatment resulted in greater delays in progression compared with dacarbazine among those patients with the most advanced melanoma (HR, 0.734 [95% CI, 0.558–0.965]; P = .028).

According to the study, nab-paclitaxel is currently recommended by the National Comprehensive Cancer Network (NCCN) as single-agent treatment for advanced or metastatic melanoma.

“Results of ongoing trials of nab-paclitaxel in combination with targeted therapies or novel immunotherapies may help expand this recommendation in the future, as nab-paclitaxel may provide a good backbone regimen to build upon given its safety profile,” the researchers wrote.

– See more at: http://www.cancernetwork.com/melanoma/nab-paclitaxel-shows-benefit-advanced-melanoma#sthash.GkUDnwms.dpuf


Immunotherapy Combination Active in Advanced Melanoma

News | April 20, 2015 | Melanoma, AACR 2015
By Leah Lawrence
Nivolumab and ipilimumab was more effective than ipilimumab alone in a…
Combined treatment with the T-cell checkpoint pathway inhibitors nivolumab and ipilimumab produced significantly higher rates of response and progression-free survival among patients with advanced melanoma (regardless of BRAF mutation status) than did treatment with ipilimumab alone, according to the phase I results of a trial published in the New England Journal of Medicine and presented at the 2015 American Association for Cancer Research (AACR) Annual Meeting.
“On the basis of the high degree of tumor reduction in the current study, with a high rate of complete responses, a favorable clinical benefit can be anticipated with longer follow-up,” wrote study author F. Stephen Hodi, MD, of the Dana-Farber Cancer Institute, and colleagues.

The phase I dose-escalation study included 142 patients with treatment-naive metastatic melanoma. Patients were randomly assigned 2:1 to ipilimumab 3 mg/kg with nivolumab 1 mg/kg or placebo every 3 weeks for four doses, followed by nivolumab 3 mg/kg or placebo every 2 weeks.

In patients with BRAF wild-type tumors, combined treatment resulted in an objective response rate of 61% compared with 11% in those assigned ipilimumab alone (P < .001). Complete responses occurred in 22% of patients assigned to the combined immunotherapy treatment and none of the patients assigned to monotherapy.

Patients with BRAF-positive disease assigned to the combination therapy had an objective response rate of 52%, with 22% of patients achieving a complete response.

“In the combination group, the objective response rate was independent of tumor PD-L1 status: 58% (95% CI, 37 to 78) among patients with PD-L1–positive tumors and 55% (95% CI, 41 to 69) among patients with PD-L1–negative tumors,” the researchers wrote. “In the ipilimumab-monotherapy group, a numerically higher objective response rate was observed among patients with PD-L1–positive tumors than among patients with PD-L1–negative tumors (18% [95% CI, 2 to 52] vs 4% [95% CI, 0 to 19]).”

Additionally, patients assigned to combination therapy did not yet reach a median progression-free survival compared with 4.4 months for ipilimumab monotherapy. The median progression-free survival for combined treatment in BRAF-positive patients was 8.5 months compared with 2.7 months in the monotherapy group.

“In general, the spectrum of select adverse events that we observed was consistent with previous experience with the combination therapy,” the researchers wrote. “Three deaths related to the combination regimen were reported in this study; these deaths could be linked to preexisting conditions that were related to the cause of death or that required medical procedures that might have contributed to the death.”

Combined treatment was associated with a higher rate of drug-related grade 3 or 4 adverse events than was monotherapy (54% vs 24%).

– See more at: http://www.cancernetwork.com/melanoma/immunotherapy-combination-active-advanced-melanoma#sthash.fEVLSw6E.dpuf


FDA Approves Ipilimumab for Earlier Stage Melanoma

News | October 30, 2015 | Melanoma
By Anna Azvolinsky, PhD

Ipilimumab (Yervoy, Bristol Myers Squibb) is now approved by the US Food and Drug Administration (FDA) as an adjuvant therapy for stage III melanoma patients.1 In this setting, the immunotherapy is used following surgery to lower the risk of relapse. Ipilimumab is already FDA-approved for the treatment of metastatic, stage IV melanoma.
The monoclonal antibody, first approved in 2011, blocks the cytotoxic T-lymphocyte antigen 4 (CTLA-4) which can slow down the ability of a patient’s immune system to fight tumor cells. Ipilimumab blocks this antigen, facilitating the immune system’s ability to recognize melanoma cells as foreign and to mount an immune response against these tumor cells.

Ipilimumab was the first immune checkpoint antibody to be approved for melanoma.

“Today’s approval of Yervoy extends its use to patients who are at high risk of developing recurrence of melanoma after surgery,” said Richard Pazdur, MD, director of the Office of Hematology and Oncology Products in FDA’s Center for Drug Evaluation and Research in a statement released by the FDA. “This new use of the drug in earlier stages of the disease builds on our understanding of the immune system’s interaction with cancer.”

According to a statement by the Melanoma Research Foundation, the approval is the first by the FDA in 20 years for an adjuvant melanoma therapy. Another available adjvuvant option for stage III patients is interferon.

The FDA approval is based on the EORTC 18071 phase III randomized, double blind clinical trial of 951 patients with high-risk stage III melanoma. All patients had complete lymph node dissection prior to starting the trial. Patients were randomized one to one to either 10 mg/kg ipilimumab or placebo infusions every 3 weeks for 4 doses, and then every 3 months for up to 3 years or to placebo.

The results were published online May 2015, in The Lancet Oncology.2

The most common reported side effects on trial were rash, diarrhea, fatigue, itching, headache, weight loss, and nausea. The most common high-grade immune-related adverse events in the ipilimumab treatment arm were gastrointestinal (16% of patients compared to <1% in the placebo arm), hepatic (11% compared to <1% in the placebo arm, and endocrine (8% compared to zero in the placebo arm).

Adverse events resulted in 52% (245 patients) of patients discontinuing treatment. Five patients (1%) died due to a drug-related adverse event in the ipilimumab treatment arm. Three patients died from colitis (two with gastrointestinal perforation), one patient because of myocarditis, and one patient because of multiorgan failure due to Guillain-Barré syndrome.

The median recurrence-free survival was 26.1 months in the ipilimumab study arm compared to 17.1 months in the placebo arm (hazard ratio of 0.75; P = .0013). The 3-year recurrence-free survival was 46.5% in the ipilimumab arm compared to 34.8% in the placebo arm.

“Adjuvant ipilimumab significantly improved recurrence-free survival for patients with completely resected high-risk stage III melanoma,” concluded the trial study authors. “The adverse event profile was consistent with that observed in advanced melanoma, but at higher incidences in particular for endocrinopathies. The risk-benefit ratio of adjuvant ipilimumab at this dose and schedule requires additional assessment based on distant metastasis-free survival and overall survival endpoints to define its definitive value.”

– See more at: http://www.cancernetwork.com/melanoma/fda-approves-ipilimumab-earlier-stage-melanoma#sthash.LRWc8XIn.dpuf

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New Guidelines and Meeting Information on Advanced Thyroid Cancer as Reported by Cancer Network (Meeting Highlights)


Reporter: Stephen J. Williams, Ph.D.

Cancer Network presents exclusive coverage on thyroid cancer from the 15th International Thyroid Congress (ITC) and 85th Annual Meeting of the American Thyroid Association (ATA), held October 18-23 in Lake Buena Vista, Florida.

Vista, Florida.
Conference Reports
ATA Updates Guidelines for Differentiated Thyroid Cancers
Release of newly revised, evidence-based clinical management guidelines for thyroid nodules and differentiated thyroid cancers were announced at the 85th Annual Meeting of the ATA.
FAM83F Protein Implicated in Papillary Thyroid Cancer and Drug Resistance
The FAM83F protein contributes to papillary thyroid cancer cell viability and doxorubicin resistance, according to a study presented at the 85th Annual Meeting of the ATA.
Autophagy Implicated in Vemurafenib Resistance in BRAF-Mutant Thyroid Cancer
Preclinical findings suggest that autophagy inhibition might prove useful in overcoming BRAF-mutant thyroid cancers resistant to vemurafenib.


Summary of Newly Released Guidelines on Management of Thyroid Nodules and Differentiated Thyroid Cancers

See Cancer.gov for more information on thyroid cancer

Release of newly revised, evidence-based clinical management guidelines for thyroid nodules and differentiated thyroid cancers were announced at the 15th International Thyroid Congress (ITC) and 85th Annual Meeting of the American Thyroid Association (ATA) in Lake Buena Vista, Florida, and published in Thyroid.

  • The ATA Guidelines Taskforce on Thyroid Nodules and Differentiated Thyroid Cancer authored the guidelines. The Taskforce was chaired by Bryan R. Haugen, MD, of the University of Colorado School of Medicine in Aurora, Colorado.

The updated guidelines reflect

  • advances in the interpretation of biopsy and the use of molecular-marker studies in the clinical differentiation of benign thyroid nodules from thyroid cancer,
  • risk assessment,
  • cancer screening,
  • the management of benign thyroid nodules,
  • the diagnosis and the initial and long-term management of differentiated thyroid cancer.
  • Guidelines modified for long-term management of differentiated thyroid cancer
  • additional research and recommendations needed “for clinical trials and targeted therapy.”

The United States saw an estimated 63,000 newly diagnosed cases of thyroid cancer cases in 2014, up sharply from 37,200 in 2009, when the ATA guidelines were last revised.

– See more at: http://www.cancernetwork.com/ata-2015-thyroid-cancer/ata-updates-guidelines-differentiated-thyroid-cancers?GUID=D63BFB74-A7FD-4892-846F-A7D1FFE0F131&XGUID=&rememberme=1&ts=20102015#sthash.yXbBrS2x.dpuf





From 2011 FDA press release on approval of vemurafenib:


For Immediate Release: Aug. 17, 2011
Media Inquiries: Erica Jefferson, 301-796-4988, erica.jefferson@fda.hhs.gov
Consumer Inquiries: 888-INFO-FDA

FDA approves Zelboraf and companion diagnostic test for late-stage skin cancer
Second melanoma drug approved this year that improves overall survival

The U.S. Food and Drug Administration today approved Zelboraf (vemurafenib), a drug to treat patients with late-stage (metastatic) or unresectable (cannot be removed by surgery) melanoma, the most dangerous type of skin cancer.

Zelboraf is specifically indicated for the treatment of patients with melanoma whose tumors express a gene mutation called BRAF V600E. The drug has not been studied in patients whose melanoma tests negative for that mutation by an FDA approved diagnostic.

Zelboraf is being approved with a first-of-a-kind test called the cobas 4800 BRAF V600 Mutation Test, a companion diagnostic that will help determine if a patient’s melanoma cells have the BRAF V600E mutation.

The BRAF protein is normally involved in regulating cell growth, but is mutated in about half of the patients with late-stage melanomas. Zelboraf is a BRAF inhibitor that is able to block the function of the V600E-mutated BRAF protein.

“This has been an important year for patients with late-stage melanoma. Zelboraf is the second new cancer drug approved that demonstrates an improvement in overall survival,” said Richard Pazdur, M.D., director of the Office of Oncology Drug Products in the FDA’s Center for Drug Evaluation and Research. “In March, we approved Yervoy (ipilimumab), another new treatment for late-stage melanoma that also showed patients live longer after receiving the drug.”

Zelboraf was reviewed under the FDA’s priority review program that provides for an expedited six-month review of drugs that may offer major advances in treatment or that provide a treatment when no adequate therapy exists. Zelboraf and the companion BRAF V600E test are being approved ahead of the drug’s Oct. 28, 2011 goal date and the companion diagnostics’ Nov. 12, 2011 goal date.

Zelboraf’s safety and effectiveness were established in a single international trial of 675 patients with late-stage melanoma with the BRAF V600E mutation who had not received prior therapy. Patients were assigned to receive either Zelboraf or dacarbazine, another anti-cancer therapy. The trial was designed to measure overall survival (the length of time between start of treatment and death of a patient).

The median survival (the length of time a patient lives after treatment) of patients receiving Zelboraf has not been reached (77 percent still living) while the median survival for those who received dacarbazine was 8 months (64 percent still living).

“Today’s approval of Zelboraf and the cobas test is a great example of how companion diagnostics can be developed and used to ensure patients are exposed to highly effective, more personalized therapies in a safe manner,” said Alberto Gutierrez, Ph.D., director of the Office of In Vitro Diagnostic Device Evaluation and Safety in the FDA’s Center for Devices and Radiological Health.

The FDA’s approval of the cobas 4800 BRAF V600 Mutation Test was based on data from the clinical study that also evaluated the safety and effectiveness of Zelboraf. Samples of a patient’s melanoma tissue were collected to test for the mutation.

The most common side effects reported in patients receiving Zelboraf included joint pain, rash, hair loss, fatigue, nausea, and skin sensitivity when exposed to the sun. About 26 percent of patients developed a skin-related cancer called cutaneous squamous cell carcinoma, which was managed with surgery. Patients treated with Zelboraf should avoid sun exposure.

Zelboraf is being approved with a Medication Guide to inform health care professionals and patients of Zelboraf’s potential risks.

In July 2011, the FDA issued a new draft guidance to facilitate the development and review of companion diagnostics. The guidance, currently available for public comment, is intended to provide companies with guidance on the agency’s policy for reviewing a companion diagnostic and the corresponding drug therapy.

Melanoma is the leading cause of death from skin disease. The National Cancer Institute estimated that 68,130 new cases of melanoma were diagnosed in the United States during 2010; about 8,700 people died from the disease.

Zelboraf is marketed by South San Francisco based-Genentech, a member of the Roche Group. The cobas 4800 BRAF V600 Mutation Test is manufactured by Roche Molecular Systems in Pleasanton, Calif.


More Articles in this Open Access Journal on Thyroid Cancer Include


The Experience of a Patient with Thyroid Cancer

Thyroid Cancer: The Evolution of Treatment Options

The Relation between Coagulation and Cancer affects Supportive Treatments


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Notes from Opening Plenary Session – The Genome and Beyond from the 2015 AACR Meeting in Philadelphia PA; Sunday April 19, 2015


Reporter: Stephen J. Williams, Ph.D.

The following contain notes from the Sunday April 19, 2015 AACR Meeting (Pennsylvania Convention Center, Philadelphia PA) 9:30 AM Opening Plenary Session

The Genome and Beyond

Session Chairperson: Lewis C. Cantley, Ph.D.

Speakers: Michael R. Stratton, Tyler Jacks, Stephen B. Baylin, Robert D. Schreiber, Williams R. Sellers

  1. A) Insights From Cancer Genomes: Michael R. Stratton, Ph.D.; Director of the Wellcome Trust Sanger Institute
  • How do we correlate mutations with causative factors of carcinogenesis and exposure?
  • Cancer was thought as a disease of somatic mutations
  • UV skin exposure – see C>T transversion in TP53 while tobacco exposure and lung cancer see more C>A transversion; Is it possible to determine EXPOSURE SIGNATURES?
  • Use a method called non negative matrix factorization (like face pattern recognition but a mutation pattern recognition)
  • Performed sequence analysis producing 12,000 mutation catalogs with 8,000 somatic mutation signatures
  • Found more mutations than expected; some mutation signatures found in all cancers, while some signatures in half of cancers, and some signatures not found in cancer
  • For example found 3 mutation signatures in ovarian cancer but 13 for breast cancers (80,000 mutations); his signatures are actually spectrums of mutations
  • kataegis: defined as localized hypermutation; an example is a signature he found related to AID/APOBEC family (involved in IgG variability); kataegis is more prone in hematologic cancers than solid cancers
  • recurrent tumors show a difference in mutation signatures than primary tumor before drug treatment


  1. B) Engineering Cancer Genomes: Tyler Jacks, Ph.D.; Director, Koch Institute for Integrative Cancer Research
  • Cancer GEM’s (genetically engineered mouse models of cancer) had moved from transgenics to defined oncogenes
  • Observation that p53 -/- mice develop spontaneous tumors (lymphomas)
  • then GEMs moved to Cre/Lox systems to generate mice with deletions however these tumor models require lots of animals, much time to create, expensive to keep;
  • figured can use CRSPR/Cas9 as rapid, inexpensive way to generate engineered mice and tumor models
  • he used CRSPR/Cas9 vectors targeting PTEN to introduce PTEN mutations in-vivo to hepatocytes; when they also introduced p53 mutations produced hemangiosarcomas; took ONLY THREE months to produce detectable tumors
  • also produced liver tumors by using CRSPR/Cas9 to introduce gain of function mutation in β-catenin


See an article describing this study by MIT News “A New Way To Model Cancer: New gene-editing technique allows scientists to more rapidly study the role of mutations in tumor development.”

The original research article can be found in the August 6, 2014 issue of Nature[1]

And see also on the Jacks Lab site under Research

  1. C) Above the Genome; The Epigenome and its Biology: Stephen B. Baylin
  • Baylin feels epigenetic therapy could be used for cancer cell reprogramming
  • Interplay between Histone (Movers) and epigenetic marks (Writers, Readers) important for developing epigenetic therapy
  • Difference between stem cells and cancer: cancer keeps multiple methylation marks whereas stem cells either keep one on or turn off marks in lineage
  • Corepressor drugs are a new exciting class in chemotherapeutic development
  • (Histone Demythylase {LSD1} inhibitors in clinical trials)
  • Bromodomain (Brd4) enhancers in clinical trials
  1. D) Using Genomes to Personalize Immunotherapy: Robert D. Schreiber, Ph.D.,
  • The three “E’s” of cancer immunoediting: Elimination, Equilibrium, and Escape
  • First evidence for immunoediting came from mice that were immunocompetent resistant to 3 methylcholanthrene (3mca)-induced tumorigenesis but RAG2 -/- form 3mca-induced tumors
  • RAG2-/- unedited (retain immunogenicity); tumors rejected by wild type mice
  • Edited tumors (aren’t immunogenic) led to tolerization of tumors
  • Can use genomic studies to identify mutant proteins which could be cancer specific immunoepitopes
  • MHC (major histocompatibility complex) tetramers: can develop vaccines against epitope and personalize therapy but only good as checkpoint block (anti-PD1 and anti CTLA4) but personalized vaccines can increase therapeutic window so don’t need to start PD1 therapy right away
  • For more details see references Schreiker 2011 Science and Shankaran 2001 in Nature
  1. E) Report on the Melanoma Keynote 006 Trial comparing pembrolizumab and ipilimumab (PD1 inhibitors)

Results of this trial were published the morning of the meeting in the New England Journal of Medicine and can be found here.

A few notes:

From the paper: The anti–PD-1 antibody pembrolizumab prolonged progression-free survival and overall survival and had less high-grade toxicity than did ipilimumab in patients with advanced melanoma. (Funded by Merck Sharp & Dohme; KEYNOTE-006 ClinicalTrials.gov number, NCT01866319.)

And from Twitter:

Robert Cade, PharmD @VTOncologyPharm

KEYNOTE-006 was presented at this week’s #AACR15 conference. Pembrolizumab blew away ipilimumab as 1st-line therapy for metastatic melanoma.

2:02 PM – 21 Apr 2015

Jeb Keiper @JebKeiper

KEYNOTE-006 at #AACR15 has pembro HR 0.63 in OS over ipi. Issue is ipi is dosed only 4 times over 2 years (per label) vs Q2W for pembro. Hmm

11:55 AM – 19 Apr 2015

OncLive.com @OncLive

Dr Antoni Ribas presenting data from KEYNOTE-006 at #AACR15 – Read more about the findings, at http://ow.ly/LMG6T 

11:25 AM – 19 Apr 2015

Joe @GantosJ

$MRK on 03/24 KEYNOTE-006 vs Yervoy Ph3 stopped early for meeting goals of PFS, OS & full data @ #AACR15 now back to weekend & family

9:05 AM – 19 Apr 2015

Kristen Slangerup @medwritekristen

Keytruda OS benefit over Yervoy in frontline #melanoma $MRK stops Ph3 early & data to come @ #AACR15 #immunotherapy http://yhoo.it/1EYwwq8 

2:40 PM – 26 Mar 2015

Yahoo Finance @YahooFinance

Merck’s Pivotal KEYNOTE-006 Study in First-Line Treatment for…

Merck , known as MSD outside the United States and Canada, today announced that the randomized, pivotal Phase 3 study investigating KEYTRUDA® compared to ipilimumab in the first-line treatment of…

View on web


Stephen J Williams @StephenJWillia2

Progression free survival better for pembrolzumab over ipilimumab by 2.5 months #AACR15 @Pharma_BI #Cancer #Immunotherapy

11:56 AM – 19 Apr 2015


Stephen J Williams @StephenJWillia2

Melanoma Keynote 006 trial PD1 inhibitor #Immunotherapy 80% responders after 1 year @Pharma_BI #AACR15



  1. Xue W, Chen S, Yin H, Tammela T, Papagiannakopoulos T, Joshi NS, Cai W, Yang G, Bronson R, Crowley DG et al: CRISPR-mediated direct mutation of cancer genes in the mouse liver. Nature 2014, 514(7522):380-384.


Other related articles on Cancer Genomics and Social Media Coverage were published in this Open Access Online Scientific Journal, include the following:

Cancer Biology and Genomics for Disease Diagnosis

Introduction – The Evolution of Cancer Therapy and Cancer Research: How We Got Here?

Methodology for Conference Coverage using Social Media: 2014 MassBio Annual Meeting 4/3 – 4/4 2014, Royal Sonesta Hotel, Cambridge, MA

List of Breakthroughs in Cancer Research and Oncology Drug Development by Awardees of The Israel Cancer Research Fund

2013 American Cancer Research Association Award for Outstanding Achievement in Chemistry in Cancer Research: Professor Alexander Levitzki

Genomics and Epigenetics: Genetic Errors and Methodologies – Cancer and Other Diseases

Cancer Genomics – Leading the Way by Cancer Genomics Program at UC Santa Cruz

Genomics and Metabolomics Advances in Cancer

Pancreatic Cancer: Genetics, Genomics and Immunotherapy

Multiple Lung Cancer Genomic Projects Suggest New Targets, Research Directions for Non-Small Cell Lung Cancer


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Imaging-guided cancer treatment

Imaging-guided cancer treatment

Writer & reporter: Dror Nir, PhD

It is estimated that the medical imaging market will exceed $30 billion in 2014 (FierceMedicalImaging). To put this amount in perspective; the global pharmaceutical market size for the same year is expected to be ~$1 trillion (IMS) while the global health care spending as a percentage of Gross Domestic Product (GDP) will average 10.5% globally in 2014 (Deloitte); it will reach ~$3 trillion in the USA.

Recent technology-advances, mainly miniaturization and improvement in electronic-processing components is driving increased introduction of innovative medical-imaging devices into critical nodes of major-diseases’ management pathways. Consequently, in contrast to it’s very small contribution to global health costs, medical imaging bears outstanding potential to reduce the future growth in spending on major segments in this market mainly: Drugs development and regulation (e.g. companion diagnostics and imaging surrogate markers); Disease management (e.g. non-invasive diagnosis, guided treatment and non-invasive follow-ups); and Monitoring aging-population (e.g. Imaging-based domestic sensors).

In; The Role of Medical Imaging in Personalized Medicine I discussed in length the role medical imaging assumes in drugs development.  Integrating imaging into drug development processes, specifically at the early stages of drug discovery, as well as for monitoring drug delivery and the response of targeted processes to the therapy is a growing trend. A nice (and short) review highlighting the processes, opportunities, and challenges of medical imaging in new drug development is: Medical imaging in new drug clinical development.

The following is dedicated to the role of imaging in guiding treatment.

Precise treatment is a major pillar of modern medicine. An important aspect to enable accurate administration of treatment is complementing the accurate identification of the organ location that needs to be treated with a system and methods that ensure application of treatment only, or mainly to, that location. Imaging is off-course, a major component in such composite systems. Amongst the available solution, functional-imaging modalities are gaining traction. Specifically, molecular imaging (e.g. PET, MRS) allows the visual representation, characterization, and quantification of biological processes at the cellular and subcellular levels within intact living organisms. In oncology, it can be used to depict the abnormal molecules as well as the aberrant interactions of altered molecules on which cancers depend. Being able to detect such fundamental finger-prints of cancer is key to improved matching between drugs-based treatment and disease. Moreover, imaging-based quantified monitoring of changes in tumor metabolism and its microenvironment could provide real-time non-invasive tool to predict the evolution and progression of primary tumors, as well as the development of tumor metastases.

A recent review-paper: Image-guided interventional therapy for cancer with radiotherapeutic nanoparticles nicely illustrates the role of imaging in treatment guidance through a comprehensive discussion of; Image-guided radiotherapeutic using intravenous nanoparticles for the delivery of localized radiation to solid cancer tumors.

 Graphical abstract


One of the major limitations of current cancer therapy is the inability to deliver tumoricidal agents throughout the entire tumor mass using traditional intravenous administration. Nanoparticles carrying beta-emitting therapeutic radionuclides [DN: radioactive isotops that emits electrons as part of the decay process a list of β-emitting radionuclides used in radiotherapeutic nanoparticle preparation is given in table1 of this paper.) that are delivered using advanced image-guidance have significant potential to improve solid tumor therapy. The use of image-guidance in combination with nanoparticle carriers can improve the delivery of localized radiation to tumors. Nanoparticles labeled with certain beta-emitting radionuclides are intrinsically theranostic agents that can provide information regarding distribution and regional dosimetry within the tumor and the body. Image-guided thermal therapy results in increased uptake of intravenous nanoparticles within tumors, improving therapy. In addition, nanoparticles are ideal carriers for direct intratumoral infusion of beta-emitting radionuclides by convection enhanced delivery, permitting the delivery of localized therapeutic radiation without the requirement of the radionuclide exiting from the nanoparticle. With this approach, very high doses of radiation can be delivered to solid tumors while sparing normal organs. Recent technological developments in image-guidance, convection enhanced delivery and newly developed nanoparticles carrying beta-emitting radionuclides will be reviewed. Examples will be shown describing how this new approach has promise for the treatment of brain, head and neck, and other types of solid tumors.

The challenges this review discusses

  • intravenously administered drugs are inhibited in their intratumoral penetration by high interstitial pressures which prevent diffusion of drugs from the blood circulation into the tumor tissue [1–5].
  • relatively rapid clearance of intravenously administered drugs from the blood circulation by kidneys and liver.
  • drugs that do reach the solid tumor by diffusion are inhomogeneously distributed at the micro-scale – This cannot be overcome by simply administering larger systemic doses as toxicity to normal organs is generally the dose limiting factor.
  • even nanoparticulate drugs have poor penetration from the vascular compartment into the tumor and the nanoparticles that do penetrate are most often heterogeneously distributed

How imaging could mitigate the above mentioned challenges

  • The inclusion of an imaging probe during drug development can aid in determining the clearance kinetics and tissue distribution of the drug non-invasively. Such probe can also be used to determine the likelihood of the drug reaching the tumor and to what extent.

Note: Drugs that have increased accumulation within the targeted site are likely to be more effective as compared with others. In that respect, Nanoparticle-based drugs have an additional advantage over free drugs with their potential to be multifunctional carriers capable of carrying both therapeutic and diagnostic imaging probes (theranostic) in the same nanocarrier. These multifunctional nanoparticles can serve as theranostic agents and facilitate personalized treatment planning.

  • Imaging can also be used for localization of the tumor to improve the placement of a catheter or external device within tumors to cause cell death through thermal ablation or oxidative stress secondary to reactive oxygen species.

See the example of Vintfolide in The Role of Medical Imaging in Personalized Medicine


Note: Image guided thermal ablation methods include radiofrequency (RF) ablation, microwave ablation or high intensity focused ultrasound (HIFU). Photodynamic therapy methods using external light devices to activate photosensitizing agents can also be used to treat superficial tumors or deeper tumors when used with endoscopic catheters.

  • Quality control during and post treatment

For example: The use of high intensity focused ultrasound (HIFU) combined with nanoparticle therapeutics: HIFU is applied to improve drug delivery and to trigger drug release from nanoparticles. Gas-bubbles are playing the role of the drug’s nano-carrier. These are used both to increase the drug transport into the cell and as ultrasound-imaging contrast material. The ultrasound is also used for processes of drug-release and ablation.


Additional example; Multifunctional nanoparticles for tracking CED (convection enhanced delivery)  distribution within tumors: Nanoparticle that could serve as a carrier not only for the therapeutic radionuclides but simultaneously also for a therapeutic drug and 4 different types of imaging contrast agents including an MRI contrast agent, PET and SPECT nuclear diagnostic imaging agents and optical contrast agents as shown below. The ability to perform multiple types of imaging on the same nanoparticles will allow studies investigating the distribution and retention of nanoparticles initially in vivo using non-invasive imaging and later at the histological level using optical imaging.



Image-guided radiotherapeutic nanoparticles have significant potential for solid tumor cancer therapy. The current success of this therapy in animals is most likely due to the improved accumulation, retention and dispersion of nanoparticles within solid tumor following image-guided therapies as well as the micro-field of the β-particle which reduces the requirement of perfectly homogeneous tumor coverage. It is also possible that the intratumoral distribution of nanoparticles may benefit from their uptake by intratumoral macrophages although more research is required to determine the importance of this aspect of intratumoral radionuclide nanoparticle therapy. This new approach to cancer therapy is a fertile ground for many new technological developments as well as for new understandings in the basic biology of cancer therapy. The clinical success of this approach will depend on progress in many areas of interdisciplinary research including imaging technology, nanoparticle technology, computer and robot assisted image-guided application of therapies, radiation physics and oncology. Close collaboration of a wide variety of scientists and physicians including chemists, nanotechnologists, drug delivery experts, radiation physicists, robotics and software experts, toxicologists, surgeons, imaging physicians, and oncologists will best facilitate the implementation of this novel approach to the treatment of cancer in the clinical environment. Image-guided nanoparticle therapies including those with β-emission radionuclide nanoparticles have excellent promise to significantly impact clinical cancer therapy and advance the field of drug delivery.

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Identifying Melanoma by Scent

Author: Tilda Barliya PhD


Researchers from the Monell Chemical Center developed a nano-sensor constructed of nano-size carbon nanotubes coated with DNA that could identify melanoma cells by scent (1).

The smell of cancer_MIT Technology

Currently, early detection of skin carcinoma is accomplished primarily through a visual exam,imaging techniques and biopsy of any suspected areas (1).

The biopsy is invasive and usually requires examination by a pathologist,  and the use of reflectance confocal microscopy and dermoscopy in situ for diagnosis of primary melanoma and other skin diseases, require specialized training.  Additionally, proteomics of caner-related biomarkers has also emerged in recent years. The discovery of cancer-related biomarkers using proteomic techniques has primarily focused on prognostic indicators of melanoma, i.e., examining the serum and plasma proteome for biomarkers indicative of metastases to distant sites (2,3).

Volatile cue however, such as those use to detect lung cancer (I), diabetes, COPD etc, have not yet been exploit in detecting melanoma. Rather volatile chemicals are released from melanoma tissues that can be differentiated from those of normal skin, posed a very interestingscientific questions.

Electronic nose that can sniff out cancer

It was no surprising that Dogs can identify by olfaction,melanoma on the skin of patients or melanoma samples hidden on healthy subjects, suggesting that volatile organic compounds (VOCs) from melanoma differ from those of normal skin. (4, 5).

D‘Amico et al. [6] employed gas chromatography/mass spectrometry (GC–MS) and a gas sensor array to investigate whether skin lesions of melanoma and nevi can be differentiated. In his paper, D’Amico had very promising results in which electronic nose sensors have been shown to have good sensitivity (with 80% accuracy) towards volatile organic compounds emitted by skin lesions, and the method seems to be effective for malign lesions identification (6).

Other attempts have been carried out to identify more closely the different VOCs of melanoma lesions compared to normal skin, however, environmental contamination rather than compounds from skin metabolism have failed to yield good detection methodology.

Kwak J et al, created an electronic nose (e-nose)  device employing functionalized DNA-coated carbon nanotube sensors, capable of sensitive and selective detection of compounds emitted from skin (1). These “single walled carbon nanotube field effect transistors (CNT FET’s), functionalized with single stranded DNA (DNACNT), have been shown to respond through a change in source drain current when exposed to VOCs” (7).

“The sensors show rapid response and recovery (seconds), very low signal drift, and chemical responses that are single strand DNA (ss-DNA) base sequence dependent. Single stranded-DNA is chosen for functionalization of the CNTs because it displays recognition for chemical vapors”.

The authors employed SPME and GC–MS to identify the VOCs that differentiate between human melanoma and normal melanocyte cells cultured in vitro, which may provide a model for in vivo human melanomas.  Same analysis were later conducted using GC–MS and DNACNT. Analysis of different normal melanocytes and melanoma cancer cell lines revealed: the growth media for normal melanocytes and cancer cells differed from each other in relative abundance of several compounds:

  • 3-hydroxy-2-butanone (acetoin),
  • 1-hexanol,
  • acetophenone,
  • phenylethyl alcohol
  • phenol

They also noted that dimethylsulfone, which has been reported, in preliminary fashion, as a significant indicator of basal cell carcinoma, was seen in significantly greater amounts in metastatic melanoma cells vs. normal cells.


It is well known that cancer cells have altered metabolisms, which are expected to yield a different profile of metabolites.The authors presented here suggest significant differences in the “volatile metabolome” of melanoma cells vs. normal melanocytes.

The authors posit that successful development of rapid screening techniques incorporating new e-nose technologies, fitted with nanosensors with high selectivity for endogenous melanoma biomarkers, may effectively scan the complex volatile fingerprints acquired from suspicious lesions and quickly provide an evaluation for the physician, regardless of their geographic location”.

Smelling a disease has also been examined in bladder cancer (8), ovarian cancer (9) as well as Parkinson and Alzheimer disease (10) and it may potentially be used to enable easy, fast and accurate method to scenting a disease.


1. Kwak J, Gallagher M, Ozdener MH, Wysocki CJ, Goldsmith BR, Isamah A, Faranda A, Fakharzadeh SS, Herlyn M, Johnson AT, Preti G. Volatile biomarkers from human melanoma cells. Journal of Chromatography B, 931 (2013) 90–96. http://www.ncbi.nlm.nih.gov/pubmed/23770738

2. S.A. Hoffman, W.A. Joo, L.A. Echan, D.W. Speicher, Higher dimensional (Hi-D) separation strategies dramatically improve the potential for cancer biomarker detection in serum and plasma.  J. Chromatogr. B: Analyt. Technol. Biomed. Life Sci. 849 (2007) 43. http://www.ncbi.nlm.nih.gov/pubmed/17140865

3.  J. Solassol, A. Du-Thanh, T. Maudelonde, B. Guillot,  Serum proteomic profiling reveals potential biomarkers for cutaneous malignant melanoma. Int. J. Biol. Markers 26 (2011) 82. http://www.ncbi.nlm.nih.gov/pubmed/21607923

4. H. Williams, A. Pembroke, SNIFFER DOGS IN THE MELANOMA CLINIC? Lancet 333 (1989) 734.  http://www.sciencedirect.com/science/article/pii/S0140673689922575
5. J. Church, H. Williams, Another sniffer dog for the clinic?  Lancet 358 (2001) 930.  http://www.sciencedirect.com/science/article/pii/S0140673601060652

6. D’Amico A, Bono R, Pennazza G, Santonico M, Mantini G, Bernabei M, Zarlenga M, Roscioni C, Martinelli E, Paolesse R, Di Natale C.  Identification of melanoma with a gas sensor array. Skin Res Technol. 2008 May;14(2):226-36.  http://www.ncbi.nlm.nih.gov/pubmed/18412567

7. C. Staii, A.T. Johnson Jr., M. Chen, A. Gelperin, DNA-Decorated Carbon Nanotubes for Chemical Sensing. Nano Lett. 5 (2005) 1774. http://pubs.acs.org/doi/abs/10.1021/nl051261f

8. Written By: Ian Anglin. SMELLING CANCER: DEVICE DETECTS BLADDER CANCER FROM ODOR OF URINE. http://singularityhub.com/2013/07/31/smelling-cancer-device-detects-bladder-cancer-from-odor-of-urine/

9. Horvath G, Chilo J, Lindblad T. Different volatile signals emitted by human ovarian carcinoma and healthy tissue.Future Oncol. 2010 Jun;6(6):1043-1049. http://www.ncbi.nlm.nih.gov/pubmed/?term=Volatile+biomarkers+from+ovarian+cacner

10. Ulrike Tisch, Ilana Schlesinger, Radu Ionescu, Maria Nassar, Noa Axelrod, Dorina Robertman, Yael Tessler, Faris Azar, Abraham Marmur, Judith Aharon-Peretz and Hossam Haick. Detection of Alzheimer’s and Parkinson’s disease from exhaled breath using nanomaterial-based sensors. Nanomedicine January 2013, Vol. 8, No. 1, Pages 43-56   http://www.futuremedicine.com/doi/abs/10.2217/nnm.12.105?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed&

Other open access article in Pharmaceutical Inteliigence

I. By: Tilda Barliya PhD. Diagnosing lung cancer in exhaled breath using gold nanoparticles.  https://pharmaceuticalintelligence.com/2012/12/01/diagnosing-lung-cancer-in-exhaled-breath-using-gold-nanoparticles/

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Reporter/Curator: Stephen J. Williams, Ph.D.

Picture of a human melanoma cell line growing in tissue culture

Cultured human melanocytes .

Nitric oxide (NO), a gas with many biological functions in healthy cells, has also been implicated in the development of pathologies such as cancer.  Nitric oxide may also play a role in chemotherapeutic reisitance. For example it had been known (in the 1996 Melanoma study by Joshi et al. curated below) that nitric oxide synthase activity (the enzyme system which produces NO) was significantly elevated in cultured melanoma cell lines versus normal melanocytes.   Although it is known that many protein and enzymes systems could be directly covalently-modified by nitric oxide, either by S-nitrosylation or NO-NAD+ modifications (one of my earlier postings described one such protein modified by nitric oxide, GAPDH, and the effect these NO-modifications of GAPDH has on the etiology of various pathologies.), the molecular mechanisms by which these modifications affect cellular processes, lead to disease etiology, the proteins which are affected, and mechanisms related to chemotherapeutic sensitivity need to be further characterized. A new study from MIT reveals how NO-induced modifications may reduce cisplatin sensitivity in melanoma cells.  This study focuses on how decreasing nitric oxide levels in melanoma cells increases their cisplatin sensitivity.  The study also describes a possible mechanism for this effect: NO-induced modifications of the proapoptotic enzyme caspace-3 and prolyl-hdroxylase-2 (responsible for targeting prosurvival HIF-1α for proteosomal degradation).  Also, for a description of other cancer-related targets of nitric oxide please see the posting by Dr. Saxena at Crucial role of Nitric Oxide in Cancer on this site.

To read more background on nitric oxide and its role in disease etiology please see our e-book Perspectives on Nitric Oxide in Disease Mechanisms (Biomed e-Books) available on Amazon at:


      It is important, however, to note that most of these relationships between NO-induced protein modification and its relationship to disease mechanisms are causal, meaning that, in general, one notices a nitric-induced modification of a protein/enzyme with concomitant alteration of protein/enzyme function occurring in a disease/phenotype.  However, unlike reversible modifications, which have a cadre of pharmacologic inhibitors, nitric oxide induced modifications are covalent and nonenzymatic, therefore hindering easy cause/effect relationships.

With that said, the following was adapted from the MIT site at http://web.mit.edu/newsoffice/2013/how-melanoma-evades-chemotherapy-0407.html.



The findings from Dr. Luiz Godoy’s PNAS paper ENDOGENOUSLY PRODUCED NITRIC OXIDE MITIGATES SENSITIVITY OF MELANOMA CELLS TO CISPLATIN,  were presented at the 2013 annual meeting of the American Association for Cancer Research. The prognosis is generally worse for patients whose tumors have high levels of NO, said Luiz Godoy, an MIT research associate and lead author of the study.

Godoy and his colleagues have unraveled the mechanism behind melanoma’s resistance to cisplatin, a commonly used chemotherapy drug, and, in ongoing studies, have found that cisplatin treatment also increases NO levels in breast and colon cancers.

“This could be a mechanism that is widely shared in different cancers, and if you use the drugs that are already used to treat cancer, along with other drugs that could scavenge or decrease the production of NO, you may have a synergistic effect,” said Godoy, who works in the lab of Gerald Wogan, an MIT professor emeritus of biological engineering and senior author of the study.

NO has many roles within living cells. At low concentrations, it helps regulate processes such as cell death and muscle contraction. NO, which is a free radical, is also important for immune-system function. Immune cells, such as macrophages, produce large amounts of NO during infection, helping to kill invading microbes by damaging their DNA or other cell components.

“It’s really a molecule that has a dual effect,” Godoy said. “At low concentrations it can act as a signaling molecule, while high concentrations will be toxic.”

Knocking out NO

In the new study, the researchers treated melanoma cells grown in the lab with drugs that capture NO before it can act. They then treated the cells with cisplatin and tracked cell-death rates. The NO-depleted cells became much more sensitive to the drug, confirming earlier findings.

The MIT team then went a step further, investigating how NO confers its survival benefits. It was already known that NO can alter protein function through a process known as S-nitrosation, which involves attaching NO to the target protein. S-nitrosation can affect many proteins, but in this study the researchers focused on two that are strongly linked with cell death and survival, known as caspase-3 and PHD2.

The role of caspase-3 is to stimulate cell suicide, under the appropriate conditions, but adding NO to the protein deactivates it. This prevents the cell from dying even when treated with cisplatin, a drug that produces massive DNA damage.

PHD2 is also involved in cell death; its role is to help break down another protein called HIF-1 alpha, which is a pro-survival protein. When NO inactivates PHD2, HIF-1 alpha stays intact and keeps the cell alive.

“Now we have a mechanistic link between nitric oxide and the increased aggressiveness of melanoma,” said Douglas Thomas, an assistant professor of medicinal chemistry and pharmacognosy at the University of Illinois at Chicago, who was not part of the research team. “It certainly would be worth exploring whether this mechanism is also present in different tumor types as well.”

The MIT researchers also found in some cancer cells, NO levels were five times higher than normal following cisplatin treatment. Godoy is now investigating how cisplatin stimulates that NO boost, and is also looking for other proteins that NO may be targeting.

Source: http://web.mit.edu/newsoffice/2013/how-melanoma-evades-chemotherapy-0407.html

Melanoma Res. 1996 Apr;6(2):121-6.

Nitric oxide synthase activity is up-regulated in melanoma cell lines: a potential mechanism for metastases formation.

Joshi M, Strandhoy J, White WL.


Department of Dermatology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157, USA.


Nitric oxide (NO) may be an important mediator of tumour angiogenesis and metastasis formation. Tumour cell derived NO may be important in the regulation of angiogenesis and vasodilatation of the blood vessels surrounding a tumour. The aims of the present study were, firstly, to determine whether malignant melanoma cells and normal melanocytes had nitric oxide synthase (NOS) activity (measured by the conversion of L-arginine to L-citrulline) and, secondly, to determine whether there was a difference in NOS activity between malignant and normal cell types. This paper assays NOS activity directly in lysates from normal human melanocyte and malignant melanoma cell lines. The enzyme activity was not inducible with bacterial lipopolysaccharide and could be heat denatured. The activity of NOS was demonstrated to be both NADPH- and calcium-dependent and it was inhibitable in a dose-dependent manner by the NOS inhibitor Nw-nitro-L-arginine methyl ester. We conclude that melanoma and melanocyte cells express a constitutive form of NOS. Finally, nitric oxide synthase activity in melanoma cell lines was found to be significantly greater than in normal melanocytes. These findings suggest that NO synthesis is elevated in malignant melanoma. An elevated NO concentration in melanoma is expected to promote metastases by maintaining a vasodilator tone in the blood vessels in and around the melanoma.

Proc Natl Acad Sci U S A. 2012 Dec 11;109(50):20373-8. doi: 10.1073/pnas.1218938109. Epub 2012 Nov 26.

Endogenously produced nitric oxide mitigates sensitivity of melanoma cells to cisplatin.

Godoy LC, Anderson CT, Chowdhury R, Trudel LJ, Wogan GN.


Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.


Melanoma patients experience inferior survival after biochemotherapy when their tumors contain numerous cells expressing the inducible isoform of NO synthase (iNOS) and elevated levels of nitrotyrosine, a product derived from NO. Although several lines of evidence suggest that NO promotes tumor growth and increases resistance to chemotherapy, it is unclear how it shapes these outcomes. Here we demonstrate that modulation of NO-mediated S-nitrosation of cellular proteins is strongly associated with the pattern of response to the anticancer agent cisplatin in human melanoma cells in vitro. Cells were shown to express iNOS constitutively, and to generate sustained nanomolar levels of NO intracellularly. Inhibition of NO synthesis or scavenging of NO enhanced cisplatin-induced apoptotic cell death. Additionally, pharmacologic agents disrupting S-nitrosation markedly increased cisplatin toxicity, whereas treatments favoring stabilization of S-nitrosothiols (SNOs) decreased its cytotoxic potency. Activity of the proapoptotic enzyme caspase-3 was higher in cells treated with a combination of cisplatin and chemicals that decreased NO/SNOs, whereas lower activity resulted from cisplatin combined with stabilization of SNOs. Constitutive protein S-nitrosation in cells was detected by analysis with biotin switch and reduction/chemiluminescence techniques. Moreover, intracellular NO concentration increased significantly in cells that survived cisplatin treatment, resulting in augmented S-nitrosation of caspase-3 and prolyl-hydroxylase-2, the enzyme responsible for targeting the prosurvival transcription factor hypoxia-inducible factor-1α for proteasomal degradation. Because activities of these enzymes are inhibited by S-nitrosation, our data thus indicate that modulation of intrinsic intracellular NO levels substantially affects cisplatin toxicity in melanoma cells. The underlying mechanisms may thus represent potential targets for adjuvant strategies to improve the efficacy of chemotherapy.

Other posts on this site regarding Nitric Oxide and Cancer include:

Crucial role of Nitric Oxide in Cancer

Nitric Oxide Covalent Modifications: A Putative Therapeutic Target?

Nitric Oxide has a ubiquitous role in the regulation of glycolysis -with a concomitant influence on mitochondrial function

Nitric Oxide Signalling Pathways

In focus: Melanoma therapeutics

Combined anti-CTLA4 and anti-PD1 immunotherapy shows promising results against advanced melanoma

Whole exome somatic mutations analysis of malignant melanoma contributes to the development of personalized cancer therapy for this disease

In focus: Melanoma therapeutics

In focus: Melanoma Genetics

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