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Posts Tagged ‘Chemotherapy’


Metastatic Gastric Cancer Treatments Indicates Mixed Results

Reporter: Irina Robu, PhD

Two novel therapies for patients with metastatic gastric cancer were evaluated by Dr. David H. Ilson of Memorial Sloan Kettering Cancer Center in New York City. In one study, trifluridine/tipiracil (FTD/TPI) was revealed to be an effective treatment for patients with metastatic gastric cancer. On the other hand, the monoclonal antibody andecaliximab plus the chemotherapy regimen mFOLFOX6 (mFOLFOX + ADX) as a first-line treatment in patients with advanced gastric or gastroesophageal junction adenocarcinoma failed to improve overall survival. He has shown the only potentially curative treatment for early stage gastric cancer is surgery, with 5-year survival rates after gastrectomy of 90% or more in Japan and Korea and 40% to 75% in non-Asian countries.

Still, the disease reappears in up to half of patients, while 40% of patients with metastatic disease have had a previous gastrectomy. The phase III TAGS study had established that FTD/TPI is safe for patients with severely pretreated metastatic gastric cancer. In this study, Ilson and his colleagues appraised the efficacy and safety of the FTD/TPI in patients with or without gastrectomy. Of the 507 patients in the study, 147 in the FTD/TPI arm had a prior gastrectomy compared to 74 in the placebo arm. The study enhances the benefit of TPI as prolonging surviving versus placebo.

According to Dr. Manish A. Shah, the mixture of mFOLFOX6 and ADX exposed encouraging anti-tumor activity in patients with gastric or gastroesophageal junction adenocarcinoma according to a prior I/IB study. He showed a phase III, randomized, double-blind, multicenter study associating the efficiency and safety of mFOLFOX with or without ADX in patients with untreated HER2-negative gastric or gastroesophageal junction adenocarcinoma.

The main endpoint was complete survival with secondary endpoints of evolution free survival, objective response rate and safety. According to Dr. Shah, thee apparent increased activity of the mixture of mFOLFOX with ADX in patients ages 65 or older needs further study.

Source

https://www.medpagetoday.com/meetingcoverage/mgics/77541

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Almudena’s Story:  A Life of Hope, Rejuvenation and Strength

Author: Gail S. Thornton, M.A.

Co-Editor: The VOICES of Patients, HealthCare Providers, Caregivers and Families: Personal Experience with Critical Care and Invasive Medical Procedures

Patient had ovarian clear cell adenocarcinomas (OCCAs) and underwent a complete hysterectomy at age 52. Interview was conducted 15 months’ post-surgery. Earlier in life, patient had thyroid cancer and removal of her thyroid gland and all the lymph nodes in her neck.

 

Almudena Seeder-Alonso, originally from Madrid, Spain, and now living in Amsterdam, The Netherlands, with her Dutch husband, René, is the eternal optimist, embracing life, reinventing herself, and looking for opportunity in every moment. She is an influential blogger of international relations issues, a career professional in human resources management in both corporate and consulting businesses in Legal, Accounting and Technology, and a lawyer and political scientist with an advanced degree in international relations who is also pursuing a Ph.D. in international relations and diplomacy. And she speaks four languages fluently – Spanish, Dutch, Portuguese and English.

Her story is one of hope, rejuvenation and strength that defines her effervescent personality. One year ago, a routine gynecology exam changed her outlook and perspective on life. She would have never thought that her diagnosis would be ovarian carcinoma of the clear cell, the most aggressive form of cancer.

 

Image SOURCE: Photographs courtesy of Almudena Seeder-Alonso. Top Left: Almudena’s parents, María and Angel, and sister, Cristina, and her husband. Top Right: Almudena during chemotherapy last summer (2015). Middle: Almudena attending a wedding in Asturias (northwest Spain – May 2016), Almudena and René in Comporta, Portugal (Summer 2014) and in New York (April 2014). Below left: Almudena in New York (April 2014). Below Right: Almudena’s sisters, María and Cristina with nephew, Jaime (May 2016). 

A Small Cyst Turns Into Diagnosis of Ovarian Cancer

In early 2015, Almudena visited her gynecologist in Amsterdam for a regular, yearly appointment.

“I was feeling fine. I had no physical complaints, except for my monthly periods which were heavy. I didn’t think much about it. During my examination, my doctor told me that she found a small cyst on my right ovary and we would just observe it to make sure it was not growing.”

Almudena went back to her gynecologist at the OLVG (Onze Lieve Vrouw Gasthuis https://www.olvg.nl/) in Amsterdam twice over the next month to monitor the cyst, only to find that the cyst was growing slightly. Her gynecologist recommended blood tests, an ultrasound, and a specimen of the cyst to be removed through a laparoscopy, a procedure requiring small incisions made below the navel using specialized tools.

“The pathology report said that the cyst was an aggressive cancer, called ovarian carcinoma of the clear cell. I remember sitting in my doctor’s office once she told me the results of the test, and I got very quiet. I could not believe that this was happening to me. While I was meeting with the doctor, I called my husband to let the doctor inform him about the situation. I was listening to this conversation but from far away. He immediately left his meeting with his client (he is one of two founding partners of SeederdeBoer, a Dutch Consulting & Technology firm), to come home. I left the doctor’s office, went home and cried in my husband’s arms.”

Almudena then called her parents, María and Angel, and her two sisters, María and Cristina who live in Madrid, to tell them the news.

“My Mother was very emotional when she heard about my diagnosis. My Father, who is a quiet man by nature, asked me, ‘How could this be happening to you again?’ I did not have an answer for him.”

Almudena’s father was referring to his daughter’s diagnosis of thyroid cancer in her late 20s.

Diagnosis of Thyroid Cancer As A Young Woman

When Almudena was 27 years old, she was diagnosed with follicular thyroid cancer, a slow-growing, highly treatable type of cancer that forms in follicular cells in the thyroid gland. After a 12-hour surgery to remove the gland through a procedure called a full thyroidectomy, she also needed radiation therapy. Many years later, she is feeling fine and continues to be on thyroid medication for the rest of her life.

“I was not aware at that young age of the scope of the diagnosis, but my life really changed. I was kind of a party animal at the end of the 1980s, and I did not have any amount of energy for that anymore. I needed several months to get back into shape as the scar from the surgery was a large one on the right side of my neck. I could not use my right arm and hand properly for months, even writing was complicated. The worst news came later when I could not get pregnant given the situation that many of my eggs were gone because of radiation. At that moment, egg freezing technology was not as advanced as it is today; it was not normal to freeze eggs for a later time. That was really painful, as I could not become a mother, even after four in vitro fertilization (IVF) cycles.”

According to the National Cancer Institute’s web site, thyroid cancer is a disease in which malignant cancer cells form in the tissues of the thyroid gland. The thyroid is a gland at the base of the throat near the trachea (windpipe). It is shaped like a butterfly, with a right lobe and a left lobe. The isthmus, a thin piece of tissue, connects the two lobes. A healthy thyroid is a little larger than a quarter coin. It usually cannot be felt through the skin. The thyroid uses iodine, a mineral found in some foods and in iodized salt, to help make several hormones. Thyroid hormones control heart rate, body temperature, and how quickly food is changed into energy (metabolism) as well as, it controls the amount of calcium in the blood.  http://www.cancer.gov/types/thyroid/patient/thyroid-treatment-pdq

Ovarian Cancer Diagnosis Continues

Almudena then spoke with her physicians in Madrid, as that is where she grew up, to get a second opinion about her ovarian carcinoma diagnosis. The physicians knew her history well and they told her that they did not believe that the follicular thyroid cancer was directly related to the ovarian cancer.

“My local gynecologist in Amsterdam then referred me to a specialist, Dr. J. van der Velden, a gynecologist/oncologist at the Amsterdam Medisch Centrum (AMC), http://www.cgoa.nl/page/view/name/34-wie-we-zijn, one of the top university hospitals in The Netherlands for this surgery and treatment. My husband, René, and I met with Dr. van der Velden, and he told us that my cancer was a fast-spreading condition and I needed to have it removed immediately. He answered our questions, calmed my fears and said he would do everything to help me.

“I have an open attitude towards people so it was easy to create a good connection with the doctors and medical personnel, which I consider very fundamental in such a process. I talked to them about my concerns or doubts and shared my worries about the process that I was going through. I have to say that all of them were wonderful in every aspect!”

Dr. van der Velden explained to Almudena that as clear cell is an aggressive form of ovarian cancer, it would need to be treated that way. One month later, Almudena underwent a procedure called open surgery, rather than laparoscopic surgery, requiring an incision large enough for the doctor to see the cyst and surrounding tissue.

“My incision from the surgery is a constant reminder of the struggle I went through. The cyst, which was 3cm, was a solid mass on my right ovary. It had adhered itself to the ovary and had to be broken to be removed, so some cells spilled out into my reproductive organs, namely, in my uterus and fallopian tubes. During this surgery, which was a complete hysterectomy, the doctor took additional tissue samples of my reproductive organs to be analyzed by pathology. Weeks later, he found no other metastases or extra cancer cells.”

http://www.mountsinai.org/patient-care/health-library/treatments-and-procedures/ovarian-cyst-removal-open-surgery

https://www.amc.nl/web/Het-AMC/Organisatie/Academisch-Medisch-Centrum.htm

The Process of Healing Begins

One month later, Almudena’s body was still recovering from the operation. Now, she had to start chemotherapy back at the OLVG.

“The doctor, Dr. W. Terpstra, hematologist/oncologist instructed me that I would be going through six full cycles of chemotherapy, which means full doses of carboplatin & paclitaxel every 21 days. At first, I felt reasonably good, then as each week progressed, I became more and more tired, nauseous, and just feeling terrible. I was not sleeping well and even lost the sensation of my fingers and toes as chemo attacks the nerves, too. Then, I started losing my eyelashes and hair so I shaved my long, flowing hair and wore a scarf wrapped around my head.”

Almudena would report to the hospital for her weekly chemotherapy session, starting at 9am and leaving at 6pm. The medical team would put her in a room with a full-size bed so she can relax during the infusion. Her husband, two sisters and some close friends would take turns accompanying her during this time, as she had a nurturing and caring support network.

“I could not have gone through this condition without my family and friends. It tests your relationships and shows you who your friends really are.”

The chemotherapy affected Almudena’s red blood cell count halfway through the process and she felt weak and tired.

“Anemia is normal during this time, but always being tired made me concentrate and focus on things less. I would watch a movie or read a book through the chemo session, and then I would fall asleep quickly.”

After Almudena finished the complete cycle of chemotherapy infusions, she had a follow-up appointment with her doctor, which included blood work, CT scan, and other diagnostic tests.

“My doctor said the tests results were very good. Now, I see him every three months for a routine visit. That was such a wonderful report to hear.

“During this process I learned to love myself, and pampered myself and my body. I learned to improve in terms of beauty, even in the worst circumstances. I wanted to feel beautiful and attractive for myself and for my close family. After three chemo cycles, I started even to think about how my new hair style would be in the moment that I finished chemo.”

Ovarian Carcinoma Pathophysiology Facts

According to published studies, ovarian clear cell adenocarcinomas (OCCAs) account for less than 5 percent of all ovarian malignancies, and 3.7–12.1 percent of all epithelial ovarian carcinomas. By contrast, early‐stage clear cell ovarian cancer carries a relatively good prognosis. When compared with their serous counterparts, a greater proportion of OCCA tumors present as early‐stage (I–II) tumors, are often associated with a large pelvic mass, which may account for their earlier diagnosis, and rarely occur bilaterally. Very little is known about the pathobiology of OCCA. Between 5 percent and 10 percent of ovarian cancers are associated with endometriotic lesions in which there is a predominance of clear and endometrioid cell subtypes, suggesting that both tumor types may arise in endometriosis. http://www.cancer.gov/types/ovarian/hp/ovarian-epithelial-treatment-pdq

The National Cancer Institute’s web site offers these statistics. In most families affected with the breast and ovarian cancer syndrome or site-specific ovarian cancer, genetic linkage has been found to the BRCA1 locus on chromosome 17q21. BRCA2, also responsible for some instances of inherited ovarian and breast cancer, has been mapped by genetic linkage to chromosome 13q12. The lifetime risk for developing ovarian cancer in patients harboring germline mutations in BRCA1 is substantially increased over that of the general population. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2001101/

Words Of Wisdom

“Throughout this journey, I found myself again in some way and found my strength as well. When it seemed I could not stand it anymore, either physically and mentally, I realized that I could.

“At the beginning of my diagnosis, I asked myself, ‘Why me?’, and I then changed it to, ‘Why not me?’ I discovered that I have the same opportunities as anyone who becomes ill. The important perspective to have is not whining and dwelling on my bad luck. The important thing is to heal, survive, and recover my life, which is very good!

“I learned the real value and importance of things: to differentiate and give real meaning and value to the care and support of my husband, René, who was always there for me, and my parents and sisters, who came to Amsterdam very often during the process. I also made sure that René was well-supported and accompanied by my family.  René was feeling terrible for me, but he never showed it — and I learned this fact after I was starting to be back on track.”

Almudena’s Life Today

“At a significant moment in my life during my cancer diagnosis and after a long professional life in many corporate and consulting business in several countries, I decided to re-invent myself and start a new career, this time, in the battle of the opinions. I always liked foreign affairs and diplomacy, so why not share my thoughts and write about current international issues.”

That’s when Almudena started a blog to discuss relevant international political issues with her background specialization in International Relations, International Politics, International Law and Governance.

“I consider myself politically liberal and have been influenced by J.S. Mill and A. Tocqueville’s tradition of thought, as well as their ethical conception of the defense of freedom. This is what I try to capture in my political approach and in this blog. http://almudenas.website/index.php/about-me/

“Regarding my profession, I have already reinvented myself, leaving the corporate life with all that is included regarding life’s standards, and do what really makes me happy, which I´m doing right now. It seems after all, looking back with perspective, I did the right thing.

“I am grateful for my life and never take anything for granted. I am the happiest when I am doing things that please me or give me the utmost satisfaction. I now have balance in my personal and professional life, something that I’ve never had before. My husband, René, likes it too and I have his full support.”

She recently ‘liked’ this saying on LinkedIn, the professional network site, ‘I never lose. I either win or learn,’ which was attributed to Nelson Mandela, the deceased South African anti-apartheid revolutionary, politician and philanthropist.

Almudena’s life continues on a path of balance, richness and thankfulness for the person she is and the many blessings she continues to have along the way.

Editor’s note:

We would like to thank Gabriela Contreras, a global communications consultant and patient advocate, for the tremendous help and support she provided in locating and scheduling time to talk with Almudena Seeder-Alonso.

Almudena Seeder-Alonso provided her permission to publish this interview on August 10, 2016.

REFERENCES/SOURCES

http://www.nytimes.com/2016/07/31/health/harnessing-the-immune-system-to-fight-cancer.html?_r=0

http://www.sharecancersupport.org/share-new/support/stories/linda_clear_cell_ovarian_cancer/

http://www.cancer.gov/types/thyroid/patient/thyroid-treatment-pdq

http://almudenas.website/index.php/about-me/

http://www.cancer.gov/types/ovarian/hp/ovarian-epithelial-treatment-pdq

http://www.cgoa.nl/page/view/name/34-wie-we-zijn

http://www.mountsinai.org/patient-care/health-library/treatments-and-procedures/ovarian-cyst-removal-open-surgery

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2001101/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2001101/

Other related articles on the link between Ovarian Cancer and Thyroid Cancer:

https://www.whatnext.com/questions/is-there-a-link-between-ovarian-and-thyroid-cancer

Other related articles/information:

https://www.olvg.nl/

https://www.amc.nl/web/Het-AMC/Organisatie/Academisch-Medisch-Centrum.htm

 

Other related articles on Ovarian Cancer and Thyroid Cancer were published in this Open Access Online Scientific Journal include the following: 

Ovarian Cancer (N = 285)

2015

A Curated History of the Science Behind the Ovarian Cancer β-Blocker Trial

Model mimicking clinical profile of patients with ovarian cancer @ Yale School of Medicine

https://pharmaceuticalintelligence.com/2015/09/26/model-mimicking-clinical-profile-of-patients-with-ovarian-cancer-yale-school-of-medicine/

2014

Preclinical study identifies ‘master’ proto-oncogene that regulates stress-induced ovarian cancer metastasis | MD Anderson Cancer Center

https://pharmaceuticalintelligence.com/2014/08/15/preclinical-study-identifies-master-proto-oncogene-that-regulates-stress-induced-ovarian-cancer-metastasis-md-anderson-cancer-center/

Good and Bad News Reported for Ovarian Cancer Therapy

https://pharmaceuticalintelligence.com/2014/07/01/good-and-bad-news-reported-for-ovarian-cancer-therapy-2/

Efficacy of Ovariectomy in Presence of BRCA1 vs BRCA2 and the Risk for Ovarian Cancer

https://pharmaceuticalintelligence.com/2014/02/25/efficacy-of-ovariectomy-in-presence-of-brca1-vs-brca2-and-the-risk-for-ovarian-cancer/

 

And 
 
Thyroid Cancer (N = 124)
2015
Experience with Thyroid Cancer

 

2012

Thyroid Cancer: The Evolution of Treatment Options

https://pharmaceuticalintelligence.com/2012/08/19/thyroid-cancer-the-evolution-of-treatment-options/

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Technologies For Targeting And Delivering Chemotherapeutics Directly To The Tumour Site

Curator: David Orchard-Webb, PhD

 

Chemotherapy is normally associated with debilitating side effects due to systemic toxicity to normal cells, however targeting the chemotherapeutics directly to the tumour should dramatically reduce these side effects. Several technologies designed to accomplish this are under development (Table 1).

 

Chemo-targeting-devices

 

Researchers of the NTU-Northwestern Institute of Nanomedicine at Nanyang Technological University in Singapore are developing magnetic microbubbles which can contain chemotherapeutics. The microbubbles can be systemically delivered and imaged in real time. The chemotherapeutic is released from the microbubbles at the tumour site by directing ultrasound at the location [1]. Therefore this technology has the potential to specifically deliver any chemotherapeutic to a desired tumour site in the body.

 

For more on nanoparticle delivery make sure to read the following pharmaceutical intelligence article concerning iCluster technology:

https://pharmaceuticalintelligence.com/2016/04/10/avoiding-chemotherapy-toxicities/

 

Researchers at PanTher Therapeutics are developing a novel drug-eluting device for targeting chemotherapeutics to solid tumours. The cremaphor formulation of paclitaxel has dose limiting toxicity which prevent its use for pancreatic cancer. Paclitaxel’s toxicity like the majority of chemotherapeutics stems from its systemic delivery and toxicity to normal cells. However recently an albumin-bound formulation (nab-paclitaxel) has demonstrated increased survival times in combination with gemcitabine compared to gemcitabine alone [2]. And now PanTher Therapeutics’ novel biodegradable device has been developed which can deliver chemotherapeutics including paclitaxel directly to the pancreas limiting systemic toxicities [3].

 

The device has been tested with paclitaxel and shown favourable results in mouse xenograft models over systemically delivered paclitaxel. The device is flexible and can be surgically placed over the pancreatic tumour where it rests delivering a steady flow of paclitaxel for the duration of the treatment. The one time insertion is an attractive aspect compared with repeated intravenous deliveries.

 

Researchers at PharmaCyte Biotech, Inc. are developing a cell encapsidation technology called Cell-in-a-Box® which protects the cells inside from the host immune system while allowing the free exchange of soluble proteins and chemicals. The chemotherapeutic ifosfamide is activated in the liver by cytochrome P450 enzymes and must travel systemically to the tumour site. The greater the distance of the tumour from the liver the greater the dose requirement for effective delivery. The toxicities induced by an effective dose for pancreatic cancer are too great. Using Cell-in-a-Box®, activated ifosfamide can however be targeted to the pancreatic cancer reducing the dose requirement.

 

Cell-in-a-Box® is made of polymers of cellulose sulphate [4]. Clinical studies have shown that it is possible to encapsulate 293 cells overexpressing cytochrome P450 and deliver the capsules to the pancreas via the blood vessels without adverse effects. Lower doses of ifosfamide can then be systemically delivered and yet have a high active local concentration at the pancreas. A phase II trial is planned to confirm effectiveness in pancreatic cancer patients refractory to gemcitabine and abraxane or FOLFIRINOX [5].

 

Researchers of the University of North Carolina at Chapel Hill have developed a new device based on inserting positive and negative electrodes on either side of a tumour, injecting a chemotherapeutic and then applying an electric field in order to drive the therapeutic into the tumour. This Iontophoresis device has been tested in pancreatic cancer mouse xenograft models with gemcitabine and the newer combination FOLFIRINOX. Significant tumour volume reductions compared to intravenous delivery of the chemotherapeutic were found in both cases [6, 7]. Clinical trials are planned in the near future [8].

 

REFERENCES

 

  1. Gao, Yu, Chon U Chan, Qiushi Gu, Xudong Lin, Wencong Zhang, David Chen Loong Yeo, Astrid Marlies Alsema, et al. ‘Controlled Nanoparticle Release from Stable Magnetic Microbubble Oscillations’. NPG Asia Materials 8, no. 4 (8 April 2016): e260. doi:10.1038/am.2016.37.
  2. Ma, W. W., and M. Hidalgo. ‘The Winning Formulation: The Development of Paclitaxel in Pancreatic Cancer’. Clinical Cancer Research 19, no. 20 (15 October 2013): 5572–79. doi:10.1158/1078-0432.CCR-13-1356.
  3. Ligorio, Matteo, Laura Indolfi, David T. Ting, Kristina Xega, Nicola Aceto, Francesca Bersani, Cristina R. Ferrone, et al. ‘Abstract 4584: A Novel Drug-Eluting Platform for Localized Treatment of Pancreatic Cancer’. Cancer Research 74, no. 19 Supplement (10 January 2014): 4584–4584. doi:10.1158/1538-7445.AM2014-4584.
  4. Gunzburg, W. H., and Brian Salmons. ‘Use of Cell Therapy as a Means of Targeting Chemotherapy to Inoperable Pancreatic Cancer’. ACTA BIOCHIMICA POLONICA-ENGLISH EDITION- 52, no. 3 (2005): 601. https://www.researchgate.net/profile/Brian_Salmons/publication/236627164_Cell_and_gene_therapy_to_improve_cancer_treatment/links/0deec52d89a7e213a2000000.pdf.
  5. ‘PharmaCyte Biotech Issues Update on Preparations for Its Pancreatic Cancer Clinical Trial Other OTC:PMCB’. Accessed 10 March 2016. https://globenewswire.com/news-release/2016/02/22/812825/0/en/PharmaCyte-Biotech-Issues-Update-on-Preparations-for-Its-Pancreatic-Cancer-Clinical-Trial.html.
  6. Byrne, J. D., M. N. R. Jajja, A. T. O’Neill, L. R. Bickford, A. W. Keeler, N. Hyder, K. Wagner, et al. ‘Local Iontophoretic Administration of Cytotoxic Therapies to Solid Tumors’. Science Translational Medicine 7, no. 273 (4 February 2015): 273ra14–273ra14. doi:10.1126/scitranslmed.3009951.
  7. Byrne, James D., Mohammad R. N. Jajja, Allison N. Schorzman, Amanda W. Keeler, J. Christopher Luft, William C. Zamboni, Joseph M. DeSimone, and Jen Jen Yeh. ‘Iontophoretic Device Delivery for the Localized Treatment of Pancreatic Ductal Adenocarcinoma’. Proceedings of the National Academy of Sciences 113, no. 8 (23 February 2016): 2200–2205. doi:10.1073/pnas.1600421113.
  8. ‘Early-Stage Drug Delivery Implant Targeting Pancreatic Cancer Tumors Showing Promise – FierceDrugDelivery’. Accessed 7 March 2016. http://www.fiercedrugdelivery.com/story/early-stage-drug-delivery-implant-targeting-pancreatic-cancer-tumors-showin/2016-02-16.

 

Other Related Articles Published In This Open Access Online Journal Include The Following:

 

https://pharmaceuticalintelligence.com/2016/04/10/avoiding-chemotherapy-toxicities/

https://pharmaceuticalintelligence.com/2015/11/09/accessing-the-blood-brain-barrier-for-chemotherapy/

https://pharmaceuticalintelligence.com/2015/09/15/why-does-cytotoxic-chemotherapy-still-remain-a-mainstay-in-many-chemotherapeutic-regimens/

https://pharmaceuticalintelligence.com/2014/06/01/development-of-a-pancreatobiliary-chemotherapy-eluting-stent-for-pancreatic-ductal-adenocarcinoma-pis-jeffrey-clark-mgh-robert-langer-koch-elazer-edelman-harvardmit-hst-program/

 

 

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Curbing Cancer Cell Growth & Metastasis-on-a-Chip’ Models Cancer’s Spread

Curator: Larry H. Bernstein, MD, FCAP

 

New Approach to Curbing Cancer Cell Growth

http://www.technologynetworks.com/Metabolomics/news.aspx?ID=189342

Using a new approach, scientists at The Scripps Research Institute (TSRI) and collaborating institutions have discovered a novel drug candidate that could be used to treat certain types of breast cancer, lung cancer and melanoma.

The new study focused on serine, one of the 20 amino acids (protein building blocks) found in nature. Many types of cancer require synthesis of serine to sustain rapid, constant and unregulated growth.

To find a drug candidate that interfered with this pathway, the team screened a large library of compounds from a variety of sources, searching for molecules that inhibited a specific enzyme known as 3-phosphoglycerate dehydrogenase (PHGDH), which is responsible for the first committed step in serine biosynthesis.

“In addition to discovering an inhibitor that targets cancer metabolism, we also now have a tool to help answer interesting questions about serine metabolism,” said Luke L. Lairson, assistant professor of chemistry at TSRI and principal investigator of cell biology at the California Institute for Biomedical Research (CALIBR).

Lairson was senior author of the study, published recently in the Proceedings of the National Academy of Sciences (PNAS), with Lewis Cantley of Weill Cornell Medical College and Costas Lyssiotis of the University of Michigan.

Addicted to Serine

Serine is necessary for nucleotide, protein and lipid biosynthesis in all cells. Cells use two main routes for acquiring serine: through import from the extracellular environment or through conversion of 3-phosphoglycerate (a glycolytic intermediate) by PHGDH.

“Since the late 1950s, it has been known that cancer cells use the process of aerobic glycolysis to generate metabolites needed for proliferative growth,” said Lairson.

This process can lead to an overproduction of serine. The genetic basis for this abundance had remained mysterious until recently, when it was demonstrated that some cancers acquire mutations that increased the expression of PHGDH; reducing PHGDH in these “serine-addicted” cancer cells also inhibited their growth.

The labs of Lewis C. Cantley at Weill Cornell Medical College (in work published in Nature Genetics) and David Sabatini at the Whitehead Institute (in work published in Nature) suggested PHGDH as a potential drug target for cancer types that overexpress the enzyme.

Lairson and colleagues hypothesized that a small molecule drug candidate that inhibited PHGDH could interfere with cancer metabolism and point the way to the development of an effective cancer therapeutic. Importantly, this drug candidate would be inactive against normal cells because they would be able to import enough serine to support ordinary growth.

As Easy as 1-2-800,000

Lairson, in collaboration with colleagues including Cantley, Lyssiotis, Edouard Mullarky of Weill Cornell and Harvard Medical School and Natasha Lucki of CALIBR, screened through a library of 800,000 small molecules using a high-throughput in vitro enzyme assay to detect inhibition of PHGDH. The group identified 408 candidates and further narrowed this list down based on cell-type specific anti-proliferative activity and by eliminating those inhibitors that broadly targeted other dehydrogenases.

With the successful identification of seven candidate inhibitors, the team sought to determine if these molecules could inhibit PHGDH in the complex cellular environment. To do so, the team used a mass spectrometry-based assay (test) to measure newly synthesized serine in a cell in the presence of the drug candidates.

One of the seven small molecules tested, named CBR-5884, was able to specifically inhibit serine synthesis by 30 percent, suggesting that the molecule specifically targeted PHGDH. The group went on to show that CBR-5884 was able to inhibit cell proliferation of breast cancer and melanoma cells lines that overexpress PHGDH.

As expected, CBR-5884 did not inhibit cancer cells that did not overexpress PHGDH, as they can import serine; however, when incubated in media lacking serine, the presence of CBR-5884 decreased growth in these cells.

The group anticipates much optimization work before this drug candidate can become an effective therapeutic. In pursuit of this goal, the researchers plan to take a medicinal chemistry approach to improve potency and metabolic stability.

 

How Cancer Stem Cells Thrive When Oxygen Is Scarce

(Image: Shutterstock)
image: Shutterstock

Working with human breast cancer cells and mice, scientists at The Johns Hopkins University say new experiments explain how certain cancer stem cells thrive in low oxygen conditions. Proliferation of such cells, which tend to resist chemotherapy and help tumors spread, are considered a major roadblock to successful cancer treatment.

The new research, suggesting that low-oxygen conditions spur growth through the same chain of biochemical events in both embryonic stem cells and breast cancer stem cells, could offer a path through that roadblock, the investigators say.

“There are still many questions left to answer but we now know that oxygen poor environments, like those often found in advanced human breast cancers serve as nurseries for the birth of cancer stem cells,” said Gregg Semenza, M.D., Ph.D., the C. Michael Armstrong Professor of Medicine and a member of the Johns Hopkins Kimmel Cancer Center. “That gives us a few more possible targets for drugs that diminish their threat in human cancer.”

A summary of the findings was published online March 21 in the Proceedings of the National Academy of Sciences.

“Aggressive cancers contain regions where the cancer cells are starved for oxygen and die off, yet patients with these tumors generally have the worst outcome. Our new findings tell us that low oxygen conditions actually encourage certain cancer stem cells to multiply through the same mechanism used by embryonic stem cells.”

All stem cells are immature cells known for their ability to multiply indefinitely and give rise to progenitor cells that mature into specific cell types that populate the body’s tissues during embryonic development. They also replenish tissues throughout the life of an organism. But stem cells found in tumors use those same attributes and twist them to maintain and enhance the survival of cancers.

Recent studies showed that low oxygen conditions increase levels of a family of proteins known as HIFs, or hypoxia-inducible factors, that turn on hundreds of genes, including one called NANOG that instructs cells to become stem cells.

Studies of embryonic stem cells revealed that NANOG protein levels can be lowered by a chemical process known as methylation, which involves putting a methyl group chemical tag on a protein’s messenger RNA (mRNA) precursor. Semenza said methylation leads to the destruction of NANOG’s mRNA so that no protein is made, which in turn causes the embryonic stem cells to abandon their stem cell state and mature into different cell types.

Zeroing in on NANOG, the scientists found that low oxygen conditions increased NANOG’s mRNA levels through the action of HIF proteins, which turned on the gene for ALKBH5, which decreased the methylation and subsequent destruction of NANOG’s mRNA. When they prevented the cells from making ALKBH5, NANOG levels and the number of cancer stem cells decreased. When the researchers manipulated the cell’s genetics to increase levels of ALKBH5 without exposing them to low oxygen, they found this also decreased methylation of NANOG mRNA and increased the numbers of breast cancer stem cells.

Finally, using live mice, the scientists injected 1,000 triple-negative breast cancer cells into their mammary fat pads, where the mouse version of breast cancer forms. Unaltered cells created tumors in all seven mice injected with such cells, but when cells missing ALKBH5 were used, they caused tumors in only 43 percent (six out of 14) of mice. “That confirmed for us that ALKBH5 helps preserve cancer stem cells and their tumor-forming abilities,” Semenza said.

How cancer stem cells thrive when oxygen is scarce    https://www.sciencedaily.com/releases/2016/03/160328100159.htm

The new research, suggesting that low-oxygen conditions spur growth through the same chain of biochemical events in both embryonic stem cells and breast cancer stem cells, could offer a path through that roadblock, the investigators say.

“There are still many questions left to answer but we now know that oxygen poor environments, like those often found in advanced human breast cancers serve as nurseries for the birth of cancer stem cells,” says Gregg Semenza, M.D., Ph.D., the C. Michael Armstrong Professor of Medicine and a member of the Johns Hopkins Kimmel Cancer Center.

Chuanzhao Zhang, Debangshu Samanta, Haiquan Lu, John W. Bullen, Huimin Zhang, Ivan Chen, Xiaoshun He, Gregg L. Semenza.
Hypoxia induces the breast cancer stem cell phenotype by HIF-dependent and ALKBH5-mediated m6A-demethylation of NANOG mRNA.
Proceedings of the National Academy of Sciences, 2016; 201602883     DOI: 10.1073/pnas.1602883113

Significance

Pluripotency factors, such as NANOG, play a critical role in the maintenance and specification of cancer stem cells, which are required for primary tumor formation and metastasis. In this study, we report that exposure of breast cancer cells to hypoxia (i.e., reduced O2 availability), which is a critical feature of the tumor microenvironment, induces N6-methyladenosine (m6A) demethylation and stabilization of NANOG mRNA, thereby promoting the breast cancer stem cell (BCSC) phenotype. We show that inhibiting the expression of AlkB homolog 5 (ALKBH5), which demethylates m6A, or the hypoxia-inducible factors (HIFs) HIF-1α and HIF-2α, which activate ALKBH5 gene transcription in hypoxic breast cancer cells, is an effective strategy to decrease NANOG expression and target BCSCs in vivo.

N6-methyladenosine (m6A) modification of mRNA plays a role in regulating embryonic stem cell pluripotency. However, the physiological signals that determine the balance between methylation and demethylation have not been described, nor have studies addressed the role of m6A in cancer stem cells. We report that exposure of breast cancer cells to hypoxia stimulated hypoxia-inducible factor (HIF)-1α- and HIF-2α–dependent expression of AlkB homolog 5 (ALKBH5), an m6A demethylase, which demethylated NANOG mRNA, which encodes a pluripotency factor, at an m6A residue in the 3′-UTR. Increased NANOG mRNA and protein expression, and the breast cancer stem cell (BCSC) phenotype, were induced by hypoxia in an HIF- and ALKBH5-dependent manner. Insertion of the NANOG 3′-UTR into a luciferase reporter gene led to regulation of luciferase activity by O2, HIFs, and ALKBH5, which was lost upon mutation of the methylated residue. ALKBH5 overexpression decreased NANOG mRNA methylation, increased NANOG levels, and increased the percentage of BCSCs, phenocopying the effect of hypoxia. Knockdown of ALKBH5 expression in MDA-MB-231 human breast cancer cells significantly reduced their capacity for tumor initiation as a result of reduced numbers of BCSCs. Thus, HIF-dependent ALKBH5 expression mediates enrichment of BCSCs in the hypoxic tumor microenvironment.

Specific Proteins Found to Jump Start Spread of Cancer Cells

http://www.genengnews.com/gen-news-highlights/specific-proteins-found-to-jump-start-spread-of-cancer-cells/81252417/

Metastatic breast cancer cells. [National Cancer Institute]
http://www.genengnews.com/Media/images/GENHighlight/thumb_Feb29_2016_NCI_MetastaticBreastCancerCells1797514764.jpg

Scientists at the University of California, San Diego School of Medicine and Moores Cancer Center, with colleagues in Spain and Germany, have discovered how elevated levels of particular proteins in cancer cells trigger hyperactivity in other proteins, fueling the growth and spread of a variety of cancers. Their study (“Prognostic Impact of Modulators of G Proteins in Circulating Tumor Cells from Patients with Metastatic Colorectal Cancer”) is published in Scientific Reports.

Specifically, the international team, led by senior author Pradipta Ghosh, M.D., associate professor at the University of California San Diego School of Medicine, found that increased levels of expression of some members of a protein family called guanine nucleotide exchange factors (GEFs) triggered unsuspected hyperactivation of G proteins and subsequent progression or metastasis of cancer.

The discovery suggests GEFs offer a new and more precise indicator of disease state and prognosis. “We found that elevated expression of each GEF is associated with a shorter, progression-free survival in patients with metastatic colorectal cancer,” said Dr. Ghosh. “The GEFs fared better as prognostic markers than two well-known markers of cancer progression, and the clustering of all GEFs together improved the predictive accuracy of each individual family member.”

In recent years, circulating tumor cells (CTCs), which are shed from primary tumors into the bloodstream and act as seeds for new tumors taking root in other parts of the body, have become a prognostic and predictive biomarker. The presence of CTCs is used to monitor the efficacy of therapies and detect early signs of metastasis.

But counting CTCs in the bloodstream has limited utility, said Dr. Ghosh. “Enumeration alone does not capture the particular characteristics of CTCs that are actually tumorigenic and most likely to cause additional malignancies.”

Numerous efforts are underway to improve the value and precision of CTC analysis. According to Dr. Ghosh the new findings are a step in that direction. First, GEFs activate trimeric G proteins, and second, G protein signaling is involved in CTCs. G proteins are ubiquitous and essential molecular switches involved in transmitting external signals from stimuli into cells’ interiors. They have been a subject of heightened scientific interest for many years.

Dr. Ghosh and colleagues found that elevated expression of nonreceptor GEFs activates Gαi proteins, fueling CTCs and ultimately impacting the disease course and survival of cancer patients.

“Our work shows the prognostic impact of elevated expression of individual and clustered GEFs on survival and the benefit of transcriptome analysis of G protein regulatory proteins in cancer biology,” said Dr. Ghosh. “The next step will be to carry this technology into the clinic where it can be applied directly to deciphering a patient’s state of cancer and how best to treat.”

Metastasis-on-a-Chip’ Models Cancer’s Spread

http://www.mdtmag.com/news/2016/03/metastasis-chip-models-cancers-spread?et_cid=5200644&et_rid=461755519

In the journal Biotechnology Bioengineering, the team reports on its “metastasis-on-a-chip” system believed to be one of the first laboratory models of cancer spreading from one 3D tissue to another.

The current version of the system models a colorectal tumor spreading from the colon to the liver, the most common site of metastasis. Skardal said future versions could include additional organs, such as the lung and bone marrow, which are also potential sites of metastasis. The team also plans to model other types of cancer, such as the deadly brain tumor glioblastoma

To create the system, researchers encapsulated human intestine and colorectal cancer cells inside a biocompatible gel-like material to make a mini-organ. A mini-liver composed of human liver cells was made in the same way. These organoids were placed in a “chip” system made up of a set of micro-channels and chambers etched into the chip’s surface to mimic a simplified version of the body’s circulatory system. The tumor cells were tagged with fluorescent molecules so their activity could be viewed under a microscope.

To test whether the system could model metastasis, the researchers first used highly aggressive cancer cells in the colon organoid. Under the microscope, they saw the tumor grow in the colon organoid until the cells broke free, entered the circulatory system and then invaded the liver tissue, where another tumor formed and grew. When a less aggressive form of colon cancer was used in the system, the tumor did not metastasize, but continued to grow in the colon.

To test the system’s potential for screening drugs, the team introduced Marimastat, a drug used to inhibit metastasis in human patients, into the system and found that it significantly prevented the migration of metastatic cells over a 10-day period. Likewise, the team also tested 5-fluorouracil, a common colorectal cancer drug, which reduced the metabolic activity of the tumor cells.

“We are currently exploring whether other established anti-cancer drugs have the same effects in the system as they do in patients,” said Skardal. “If this link can be validated and expanded, we believe the system can be used to screen drug candidates for patients as a tool in personalized medicine. If we can create the same model systems, only with tumor cells from an actual patient, then we believe we can use this platform to determine the best therapy for any individual patient.”

The scientists are currently working to refine their system. They plan to use 3D printing to create organoids more similar in function to natural organs. And they aim to make the process of metastasis more realistic. When cancer spreads in the human body, the tumor cells must break through blood vessels to enter the blood steam and reach other organs. The scientists plan to add a barrier of endothelial cells, the cells that line blood vessels, to the model.

This concept of modeling the body’s processes on a miniature level is made possible because of advances in micro-tissue engineering and micro-fluidics technologies. It is similar to advances in the electronics industry made possible by miniaturizing electronics on a chip.

Scientists Synthesize Anti-Cancer Agent

A schematic shows a trioxacarcin C molecule, whose structure was revealed for the first time through a new process developed by the Rice lab of synthetic organic chemist K.C. Nicolaou. Trioxacarcins are found in bacteria but synthetic versions are needed to study them for their potential as medications. Trioxacarcins have anti-cancer properties. Source: Nicolaou Group/Rice University
A schematic shows a trioxacarcin C molecule, whose structure was revealed for the first time through a new process developed by the Rice lab of synthetic organic chemist K.C. Nicolaou. Trioxacarcins are found in bacteria but synthetic versions are needed to study them for their potential as medications. Trioxacarcins have anti-cancer properties. Source: Nicolaou Group/Rice University  http://www.dddmag.com/sites/dddmag.com/files/ddd1603_rice-anticancer.jpg

A team led by Rice University synthetic organic chemist K.C. Nicolaou has developed a new process for the synthesis of a series of potent anti-cancer agents originally found in bacteria.

The Nicolaou lab finds ways to replicate rare, naturally occurring compounds in larger amounts so they can be studied by biologists and clinicians as potential new medications. It also seeks to fine-tune the molecular structures of these compounds through analog design and synthesis to improve their disease-fighting properties and lessen their side effects.

Such is the case with their synthesis of trioxacarcins, reported this month in the Journal of the American Chemical Society.

“Not only does this synthesis render these valuable molecules readily available for biological investigation, but it also allows the previously unknown full structural elucidation of one of them,” Nicolaou said. “The newly developed synthetic technologies will allow us to construct variations for biological evaluation as part of a program to optimize their pharmacological profiles.”

At present, there are no drugs based on trioxacarcins, which damage DNA through a novel mechanism, Nicolaou said.

Trioxacarcins were discovered in the fermentation broth of the bacterial strain Streptomyces bottropensis. They disrupt the replication of cancer cells by binding and chemically modifying their genetic material.

“These molecules are endowed with powerful anti-tumor properties,” Nicolaou said. “They are not as potent as shishijimicin, which we also synthesized recently, but they are more powerful than taxol, the widely used anti-cancer drug. Our objective is to make it more powerful through fine-tuning its structure.”

He said his lab is working with a biotechnology partner to pair these cytotoxic compounds (called payloads) to cancer cell-targeting antibodies through chemical linkers. The process produces so-called antibody-drug conjugates as drugs to treat cancer patients. “It’s one of the latest frontiers in personalized targeting chemotherapies,” said Nicolaou, who earlier this year won the prestigious Wolf Prize in Chemistry.

Fluorescent Nanoparticle Tracks Cancer Treatment’s Effectiveness in Hours

Bevin Fletcher, Associate Editor    http://www.biosciencetechnology.com/news/2016/03/fluorescent-nanoparticle-tracks-cancer-treatments-effectiveness-hours

Using reporter nanoparticles loaded with either a chemotherapy or immunotherapy, researchers could distinguish between drug-sensitive and drug-resistant tumors in a pre-clinical model of prostate cancer. (Source: Brigham and Women's Hospital)

Using reporter nanoparticles loaded with either a chemotherapy or immunotherapy, researchers could distinguish between drug-sensitive and drug-resistant tumors in a pre-clinical model of prostate cancer. (Source: Brigham and Women’s Hospital)

Bioengineers at Brigham and Women’s Hospital have developed a new technique to help determine if chemotherapy is working in as few as eight hours after treatment. The new approach, which can also be used for monitoring the effectiveness of immunotherapy, has shown success in pre-clinical models.

The technology utilizes a nanoparticle, carrying anti-cancer drugs, that glows green when cancer cells begin dying. Researchers, using  the “reporter nanoparticles” that responds to a particular enzyme known as caspase, which is activated when cells die, were able to distinguish between a tumor that is drug-sensitive or drug-resistant much faster than conventional detection methods such as PET scans, CT and MRI.  The findings were published online March 28 in the Proceedings of the National Academy of Sciences.

“Using this approach, the cells light up the moment a cancer drug starts working,” co-corresponding author Shiladitya Sengupta, Ph.D., principal investigator in BWH’s Division of Bioengineering, said in a prepared statement.  “We can determine if a cancer therapy is effective within hours of treatment.  Our long-term goal is to find a way to monitor outcomes very early so that we don’t give a chemotherapy drug to patients who are not responding to it.”

Cancer killers send signal of success

Nanoparticles deliver drug, then give real-time feedback when tumor cells die   BY   SARAH SCHWARTZ

New lab-made nanoparticles deliver cancer drugs into tumors, then report their effects in real time by lighting up in response to proteins produced by dying cells. More light (right, green) indicates a tumor is responding to chemotherapy.

Tiny biochemical bundles carry chemotherapy drugs into tumors and light up when surrounding cancer cells start dying. Future iterations of these lab-made particles could allow doctors to monitor the effects of cancer treatment in real time, researchers report the week of March 28 in theProceedings of the National Academy of Sciences.

“This is the first system that allows you to read out whether your drug is working or not,” says study coauthor Shiladitya Sengupta, a bioengineer at Brigham and Women’s Hospital in Boston.

Each roughly 100-nanometer-wide particle consists of a drug and a fluorescent dye linked to a coiled molecular chain. Before the particles enter cells, the dye is tethered to a “quencher” molecule that prevents it from lighting up. When injected into the bloodstream of a mouse with cancer, the nanoparticles accumulate in tumor cells and release the drug, which activates a protein that tears a cancer cell apart. This cell-splitting protein not only kills the tumor cell, but also severs the link between the dye and the quencher, allowing the nanoparticles to glow under infrared light.

Reporter nanoparticle that monitors its anticancer efficacy in real time

Ashish Kulkarnia,b,1,Poornima Raoa,b,Siva Natarajana,b,Aaron Goldman, et al.
http://www.pnas.org/content/early/2016/03/28/1603455113.abstract

The ability to identify responders and nonresponders very early during chemotherapy by direct visualization of the activity of the anticancer treatment and to switch, if necessary, to a regimen that is effective can have a significant effect on the outcome as well as quality of life. Current approaches to quantify response rely on imaging techniques that fail to detect very early responses. In the case of immunotherapy, the early anatomical readout is often discordant with the biological response. This study describes a self-reporting nanomedicine that not only delivers chemotherapy or immunotherapy to the tumor but also reports back on its efficacy in real time, thereby identifying responders and nonresponders early on

The ability to monitor the efficacy of an anticancer treatment in real time can have a critical effect on the outcome. Currently, clinical readouts of efficacy rely on indirect or anatomic measurements, which occur over prolonged time scales postchemotherapy or postimmunotherapy and may not be concordant with the actual effect. Here we describe the biology-inspired engineering of a simple 2-in-1 reporter nanoparticle that not only delivers a cytotoxic or an immunotherapy payload to the tumor but also reports back on the efficacy in real time. The reporter nanoparticles are engineered from a novel two-staged stimuli-responsive polymeric material with an optimal ratio of an enzyme-cleavable drug or immunotherapy (effector elements) and a drug function-activatable reporter element. The spatiotemporally constrained delivery of the effector and the reporter elements in a single nanoparticle produces maximum signal enhancement due to the availability of the reporter element in the same cell as the drug, thereby effectively capturing the temporal apoptosis process. Using chemotherapy-sensitive and chemotherapy-resistant tumors in vivo, we show that the reporter nanoparticles can provide a real-time noninvasive readout of tumor response to chemotherapy. The reporter nanoparticle can also monitor the efficacy of immune checkpoint inhibition in melanoma. The self-reporting capability, for the first time to our knowledge, captures an anticancer nanoparticle in action in vivo.

 

Cancer Treatment’s New Direction  
Genetic testing helps oncologists target tumors and tailor treatments
http://www.wsj.com/articles/cancer-treatments-new-direction-1459193085

Evan Johnson had battled a cold for weeks, endured occasional nosebleeds and felt so fatigued he struggled to finish his workouts at the gym. But it was the unexplained bruises and chest pain that ultimately sent the then 23-year-old senior at the University of North Dakota to the Mayo Clinic. There a genetic test revealed a particularly aggressive form of acute myeloid leukemia. That was two years ago.

The harrowing roller-coaster that followed for Mr. Johnson and his family highlights new directions oncologists are taking with genetic testing to find and attack cancer. Tumors can evolve to resist treatments, and doctors are beginning to turn such setbacks into possible advantages by identifying new targets to attack as the tumors change.

His course involved a failed stem cell transplant, a half-dozen different drug regimens, four relapses and life-threatening side effects related to his treatment.

Nine months in, his leukemia had evolved to develop a surprising new mutation. The change meant the cancer escaped one treatment, but the new anomaly provided doctors with a fresh target, one susceptible to drugs approved for other cancers. Doctors adjusted Mr. Johnson’s treatment accordingly, knocked out the disease and paved the way for a second, more successful stem cell transplant. He has now been free of leukemia for a year.

Now patients with advanced cancer who are treated at major centers can expect to have their tumors sequenced, in hopes of finding a match in a growing medicine chest of drugs that precisely target mutations that drive cancer’s growth. When they work, such matches can have a dramatic effect on tumors. But these “precision medicines” aren’t cures. They are often foiled when tumors evolve, pushing doctors to take the next step to identify new mutations in hopes of attacking them with an effective treatment.

Dr. Kasi and his Mayo colleagues—Naseema Gangat, a hematologist, and Shahrukh Hashmi, a transplant specialist—are among the authors of an account of Mr. Johnson’s case published in January in the journal Leukemia Research Reports.

Before qualifying for a transplant, a patient’s blasts need to be under 5%.

To get under 5%, he started on a standard chemotherapy regimen and almost immediately, things went south. His blast cells plummeted, but “the chemo just wiped out my immune system,”

Then as mysteriously as it began, a serious mycotic throat infection stopped. But Mr. Johnson couldn’t tolerate the chemo, and his blast cells were on the rise. A two-drug combination that included the liver cancer drug Nexavar, which targets the FLT3 mutation, knocked back the blast cells. But the stem cell transplant in May, which came from one of his brothers, failed to take, and he relapsed after 67 days, around late July.

He was put into a clinical trial of an experimental AML drug being developed by Astellas Pharma of Japan. He started to regain weight. In November 2014, doctors spotted the initial signs in blood tests that Mr. Johnson’s cancer was evolving to acquire a new mutation. By late January, he relapsed again , but there was a Philadelphia chromosome mutation,  a well-known genetic alteration associated with chronic myeloid leukemia. It also is a target of the blockbuster cancer drug Gleevec and several other medicines.

Clonal evolution of AML on novel FMS-like tyrosine kinase-3 (FLT3) inhibitor therapy with evolving actionable targets

Naseema GangatMark R. LitzowMrinal M. PatnaikShahrukh K. HashmiNaseema Gangat

Highlights
•   The article reports on a case of AML that underwent clonal evolution.
•   We report on novel acquisition of the Philadelphia t(9;22) translocation in AML.
•   Next generation sequencing maybe helpful in these refractory/relapse cases.
•   Novel FLT3-inhibitor targeted therapies are another option in patients with AML.
•   Personalizing cancer treatment based on evolving targets is a viable option.

For acute myeloid leukemia (AML), identification of activating mutations in the FMS-like tyrosine kinase-3 (FLT3) has led to the development of several FLT3-inhibitors. Here we present clinical and next generation sequencing data at the time of progression of a patient on a novel FLT3-inhibitor clinical trial (ASP2215) to show that employing therapeutic interventions with these novel targeted therapies can lead to consequences secondary to selective pressure and clonal evolution of cancer. We describe novel findings alongside data on treatment directed towards actionable aberrations acquired during the process. (Clinical Trial: NCT02014558; registered at: 〈https://clinicaltrials.gov/ct2/show/NCT02014558〉)

The development of kinase inhibitors for the treatment of leukemia has revolutionized the care of these patients. Since the introduction of imatinib for the treatment of chronic myeloid leukemia, multiple other tyrosine kinase inhibitors (TKIs) have become available[1]. Additionally, for acute myeloid leukemia (AML), identification of activating mutations in the FMS-like tyrosine kinase-3 (FLT3) has led to the development of several FLT3-inhibitors [2], [3], [4] and [5]. The article herein reports a unique case of AML that underwent clonal evolution while on a novel FLT3-inhibitor clinical trial.

Our work herein presents clinical and next generation sequencing data at the time of progression to illustrate these important concepts stemming from Darwinian evolution [6]. We describe novel findings alongside data on treatment directed towards actionable aberrations acquired during the process.

Our work focuses on a 23-year-old male who presented with 3 months history of fatigue and easy bruising, a white blood count of 22.0×109/L with 51% circulating blasts, hemoglobin 7.6 g/dL, and a platelet count of 43×109/L. A bone marrow biopsy confirmed a diagnosis of AML. Initial cytogenetic studies identified trisomy 8 in all the twenty metaphases examined. Mutational analysis revealed an internal tandem duplication of the FLT3 gene (FLT3-ITD).

He received standard induction chemotherapy (7+3) with cytarabine (ARA-C; 100 mg/m2for 7 days) and daunorubicin (DNM; 60 mg/m2 for 3 days). His induction chemotherapy was complicated by severe palatine and uvular necrosis of indeterminate etiology (possible mucormycosis).

Bone marrow biopsy at day 28 demonstrated persistent disease with 10% bone marrow blasts (Fig. 1). Due to his complicated clinical course and the presence of a FLT3-ITD, salvage therapy with 5-azacitidine (5-AZA) and sorafenib (SFN) was instituted. Table 1.
The highlighted therapies were employed in this particular case at various time points as shown in Fig. 1.

http://ars.els-cdn.com/content/image/1-s2.0-S221304891530025X-gr1.jpg

References

    • [1]
    • J.E. Cortes, D.W. Kim, J. Pinilla-Ibarz, et al.
    • A phase 2 trial of ponatinib in Philadelphia chromosome-positive leukemias
    • New Engl. J. Med., 369 (19) (2013), pp. 1783–1796
    • [2]
    • F. Ravandi, M.L. Alattar, M.R. Grunwald, et al.
    • Phase 2 study of azacytidine plus sorafenib in patients with acute myeloid leukemia and FLT-3 internal tandem duplication mutation
    • Blood, 121 (23) (2013), pp. 4655–4662
    • [3]
    • N.P. Shah, M. Talpaz, M.W. Deininger, et al.
    • Ponatinib in patients with refractory acute myeloid leukaemia: findings from a phase 1 study
    • Br. J. Haematol., 162 (4) (2013), pp. 548–552
    • [4]
    • Y. Alvarado, H.M. Kantarjian, R. Luthra, et al.
    • Treatment with FLT3 inhibitor in patients with FLT3-mutated acute myeloid leukemia is associated with development of secondary FLT3-tyrosine kinase domain mutations
    • Cancer, 120 (14) (2014), pp. 2142–2149
    • [5]
    • C.C. Smith, C. Zhang, K.C. Lin, et al.
    • Characterizing and overriding the structural mechanism of the Quizartinib-Resistant FLT3 “Gatekeeper” F691L mutation with PLX3397
    • Cancer Discov. (2015)
    • [6]
    • M. Greaves, C.C. Maley
    • Clonal evolution in cancer
    • Nature, 481 (7381) (2012), pp. 306–313

 

 

 

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Novel Mechanisms of Resistance to Novel Agents

 

Curators: Larry H. Berstein, M.D. FACP & Stephen J. Williams, Ph.D.

For most of the history of chemotherapy drug development, predicting the possible mechanisms of drug resistance that ensued could be surmised from the drug’s pharmacologic mechanism of action. In other words, a tumor would develop resistance merely by altering the pathways/systems which the drug relied on for mechanism of action. For example, as elucidated in later chapters in this book, most cytotoxic chemotherapies like cisplatin and cyclophosphamide were developed to bind DNA and disrupt the cycling cell, thereby resulting in cell cycle arrest and eventually cell death or resulting in such a degree of genotoxicity which would result in great amount of DNA fragmentation. These DNA-damaging agents efficacy was shown to be reliant on their ability to form DNA adducts and lesions. Therefore increasing DNA repair could result in a tumor cell becoming resistant to these drugs. In addition, if drug concentration was merely decreased in these cells, by an enhanced drug efflux as seen with the ABC transporters, then there would be less drug available for these DNA adducts to be generated. A plethora of literature has been generated on this particular topic.

However in the era of chemotherapies developed against targets only expressed in tumor cells (such as Gleevec against the Bcr-Abl fusion protein in chronic myeloid leukemia), this paradigm had changed as clinical cases of resistance had rapidly developed soon after the advent of these compounds and new paradigms of resistance mechanisms were discovered.

speed of imitinib resistance

Imatinib resistance can be seen quickly after initiation of therapy

mellobcrablresistamplification

Speed of imatinib resistance a result of rapid gene amplification of BCR/ABL target, thereby decreasing imatinib efficacy

 

 

 

 

 

 

 

 

 

 

Although there are many other new mechanisms of resistance to personalized medicine agents (which are discussed later in the chapter) this post is a curation of cellular changes which are not commonly discussed in reviews of chemoresistance and separated in three main categories:

Cellular Diversity and Adaptation

Identifying Cancers and Resistance

Cancer Drug-Resistance Mechanism

p53 tumor drug resistance gene target

Variability of Gene Expression and Drug Resistance

 

Expression of microRNAs and alterations in RNA resulting in chemo-resistance

Drug-resistance Mechanism in Tumor Cells

Overexpression of miR-200c induces chemoresistance in esophageal cancers mediated through activation of the Akt signaling pathway

 

The miRNA–drug resistance connection: a new era of personalized medicine using noncoding RNA begins

 

Gene Duplication of Therapeutic Target

 

The advent of Gleevec (imatinib) had issued in a new era of chemotherapy, a personalized medicine approach by determining the and a lifesaver to chronic myeloid leukemia (CML) patients whose tumors displayed expression of the Bcr-Abl fusion gene. However it was not long before clinical resistance was seen to this therapy and, it was shown amplification of the drug target can lead to tumor outgrowth despite adequate drug exposure. le Coutre, Weisberg and Mahon23, 24, 25 all independently generated imatinib-resistant clones through serial passage of the cells in imatinib-containing media and demonstrated elevated Abl kinase activity due to a genetic amplification of the Bcr–Abl sequence. However, all of these samples were derived in vitro and may not represent a true mode of clinical resistance. Nevertheless, Gorre et al.26 obtained specimens, directly patients demonstrating imatinib resistance, and using fluorescence in situ hybridization analysis, genetic duplication of the Bcr–Abl gene was identified as one possible source of the resistance. Additional sporadic examples of amplification of the Bcr–Abl sequence have been clinically described, but the majority of patients presenting with either primary or secondary imatinib resistance fail to clinically demonstrate Abl amplification as a primary mode of treatment failure.

This is seen in the following papers:

Clinical resistance to STI-571 cancer therapy caused by BCR-ABL gene mutation or amplification.Gorre ME, Mohammed M, Ellwood K, Hsu N, Paquette R, Rao PN, Sawyers CL. Science. 2001 Aug 3;293(5531):876-80. Epub 2001 Jun 21.

and in another original paper by le Coutre et. al.

Induction of resistance to the Abelson inhibitor STI571 in human leukemic cells through gene amplification. le Coutre P1, Tassi E, Varella-Garcia M, Barni R, Mologni L, Cabrita G, Marchesi E, Supino R, Gambacorti-Passerini C. Blood. 2000 Mar 1;95(5):1758-66

The 2-phenylaminopyrimidine derivative STI571 has been shown to selectively inhibit the tyrosine kinase domain of the oncogenic bcr/abl fusion protein. The activity of this inhibitor has been demonstrated so far both in vitro with bcr/abl expressing cells derived from leukemic patients, and in vivo on nude mice inoculated with bcr/abl positive cells. Yet, no information is available on whether leukemic cells can develop resistance to bcr/abl inhibition. The human bcr/abl expressing cell line LAMA84 was cultured with increasing concentrations of STI571. After approximately 6 months of culture, a new cell line was obtained and named LAMA84R. This newly selected cell line showed an IC50 for the STI571 (1.0 microM) 10-fold higher than the IC50 (0.1 microM) of the parental sensitive cell line. Treatment with STI571 was shown to increase both the early and late apoptotic fraction in LAMA84 but not in LAMA84R. The induction of apoptosis in LAMA84 was associated with the activation of caspase 3-like activity, which did not develop in the resistant LAMA84R cell line. LAMA84R cells showed increased levels of bcr/abl protein and mRNA when compared to LAMA84 cells. FISH analysis with BCR- and ABL-specific probes in LAMA84R cells revealed the presence of a marker chromosome containing approximately 13 to 14 copies of the BCR/ABL gene. Thus, overexpression of the Bcr/Abl protein mediated through gene amplification is associated with and probably determines resistance of human leukemic cells to STI571 in vitro. (Blood. 2000;95:1758-1766)

This is actually the opposite case with other personalized therapies like the EGFR inhibitor gefinitib where actually the AMPLIFICATION of the therapeutic target EGFR is correlated with better response to drug in

Molecular mechanisms of epidermal growth factor receptor (EGFR) activation and response to gefitinib and other EGFR-targeting drugs.Ono M, Kuwano M. Clin Cancer Res. 2006 Dec 15;12(24):7242-51. Review.

Abstract

The epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases, including EGFR, HER2/erbB2, and HER3/erbB3, is an attractive target for antitumor strategies. Aberrant EGFR signaling is correlated with progression of various malignancies, and somatic tyrosine kinase domain mutations in the EGFR gene have been discovered in patients with non-small cell lung cancer responding to EGFR-targeting small molecular agents, such as gefitinib and erlotinib. EGFR overexpression is thought to be the principal mechanism of activation in various malignant tumors. Moreover, an increased EGFR copy number is associated with improved survival in non-small cell lung cancer patients, suggesting that increased expression of mutant and/or wild-type EGFR molecules could be molecular determinants of responses to gefitinib. However, as EGFR mutations and/or gene gains are not observed in all patients who respond partially to treatment, alternative mechanisms might confer sensitivity to EGFR-targeting agents. Preclinical studies showed that sensitivity to EGFR tyrosine kinase inhibitors depends on how closely cell survival and growth signalings are coupled with EGFR, and also with HER2 and HER3, in each cancer. This review also describes a possible association between EGFR phosphorylation and drug sensitivity in cancer cells, as well as discussing the antiangiogenic effect of gefitinib in association with EGFR activation and phosphatidylinositol 3-kinase/Akt activation in vascular endothelial cells.

 

Mutant Variants of Therapeutic Target

 

resistant subclones in tissue samples and Tyrosine Kinase tumor activity

 

Mitochondrial Isocitrate Dehydrogenase and Variants

Mutational Landscape of Rare Childhood Brain Cancer: Analysis of 60 Intercranial Germ Cell Tumor Cases using NGS, SNP and Expression Array Analysis – Signaling Pathways KIT/RAS are affected by mutations in IGCTs

 

AND seen with the ALK inhibitors as well (as seen in the following papers

Acquisition of cancer stem cell-like properties in non-small cell lung cancer with acquired resistance to afatinib.

Hashida S, Yamamoto H, Shien K, Miyoshi Y, Ohtsuka T, Suzawa K, Watanabe M, Maki Y, Soh J, Asano H, Tsukuda K, Miyoshi S, Toyooka S. Cancer Sci. 2015 Oct;106(10):1377-84. doi: 10.1111/cas.12749. Epub 2015 Sep 30.

In vivo imaging models of bone and brain metastases and pleural carcinomatosis with a novel human EML4-ALK lung cancer cell line.

Nanjo S, Nakagawa T, Takeuchi S, Kita K, Fukuda K, Nakada M, Uehara H, Nishihara H, Hara E, Uramoto H, Tanaka F, Yano S. Cancer Sci. 2015 Mar;106(3):244-52. doi: 10.1111/cas.12600. Epub 2015 Feb 17.

Identification of a novel HIP1-ALK fusion variant in Non-Small-Cell Lung Cancer (NSCLC) and discovery of ALK I1171 (I1171N/S) mutations in two ALK-rearranged NSCLC patients with resistance to Alectinib. Ou SH, Klempner SJ, Greenbowe JR, Azada M, Schrock AB, Ali SM, Ross JS, Stephens PJ, Miller VA.J Thorac Oncol. 2014 Dec;9(12):1821-5

Reports of chemoresistance due to variants have also been seen with the BRAF inhibitors like vemurafenib and dabrafenib:

The RAC1 P29S hotspot mutation in melanoma confers resistance to pharmacological inhibition of RAF.

Watson IR, Li L, Cabeceiras PK, Mahdavi M, Gutschner T, Genovese G, Wang G, Fang Z, Tepper JM, Stemke-Hale K, Tsai KY, Davies MA, Mills GB, Chin L.Cancer Res. 2014 Sep 1;74(17):4845-52. doi: 10.1158/0008-5472.CAN-14-1232-T. Epub 2014 Jul 23

 

 

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New Generation of Platinated Compounds to Circumvent Resistance

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

Resistance to chemotherapeutic drugs continues to be a major hurdle in the treatment of neoplastic disorders, irregardless if the drug is a member of the cytotoxic “older” drugs or the cytostatic “newer” personalized therapies like the tyrosine kinase inhibitors.  For the platinatum compounds such as cisplatin and carboplatin, which are mainstays in therapeutic regimens for ovarian and certain head and neck cancers, development of resistance is often regarded as the final blow, as new options for these diseases have been limited.

Although there are many mechanisms by which resistance to platinated compounds may develop the purpose of this posting is not to do an in-depth review of this area except to refer the reader to the book   Ovarian Cancer and just to summarize the well accepted mechanisms of cisplatin resistance including:

  • Decreased cellular cisplatin influx
  • Increased cellular cisplatin efflux
  • Increased cellular glutathione and subsequent conjugation, inactivation
  • Increased glutathione-S-transferase activity (GST) and subsequent inactivation, conjugation
  • Increased γ-GGT
  • Increased metallothionenes with subsequent conjugation, inactivation
  • Increased DNA repair: increased excision repair
  • DNA damage tolerance: loss of mismatch repair (MMR)
  • altered cell signaling activities and cell cycle protein expression

Williams, S.J., and Hamilton, T.C. Chemotherapeutic resistance in ovarian cancer. In: S.C. Rubin, and G.P. Sutton (eds.), Ovarian Cancer, pp.34-44. Lippincott, Wilkins, and Williams, New York, 2000.

Also for a great review on clinical platinum resistance by Drs. Maritn, Hamilton and Schilder please see the following Clinical Cancer Research link here.

This curation represents the scientific rationale for the development of a new class of platinated compounds which are meant to circumvent mechanisms of resistance, in this case the loss of mismatch repair (MMR) and increased tolerance to DNA damage.

An early step in the production of cytotoxicity by the important anticancer drug cisplatin and its analog carboplatin is the formation of intra- and inter-strand adducts with tumor cell DNA 1-3. This damage triggers a cascade of events, best characterized by activation of damage-sensing kinases (reviewed in 4), p53 stabilization, and induction of p53-related genes involved in apoptosis and cell cycle arrest, such as bax and the cyclin-dependent kinase inhibitor p21waf1/cip1/sdi1 (p21), respectively 5,6. DNA damage significantly induces p21 in various p53 wild-type tumor cell lines, including ovarian carcinoma cells, and this induction is responsible for the cell cycle arrest at G1/S and G2/M borders, allowing time for repair 7,8.  DNA lesions have the ability of  to result in an opening of chromatin structure, allowing for transcription factors to enter 56-58.  Therefore the anti-tumoral ability of cisplatin and other DNA damaging agents is correlated to their ability to bind to DNA and elicit responses, such as DNA breaks or DNA damage responses which ultimately lead to cell cycle arrest and apoptosis.  Therefore either repair of such lesions, the lack of recognition of such lesions, or the cellular tolerance of such lesions can lead to resistance of these agents.

resistmech2

Mechanisms of Cisplatin Sensitivity and Resistance. Red arrows show how a DNA lesion results in chemo-sensitivity while the beige arrow show common mechanisms of resistance including increased repair of the lesion, effects on expression patterns, and increased inactivation of the DNA damaging agent by conjugation reactions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

mechPtresistance

 

 

Increased DNA Repair Mechanisms of Platinated Lesion Lead to ChemoResistance

 

DNA_repair_pathways

Description of Different Types of Cellular DNA Repair Pathways. Nucleotide Excision Repair is commonly up-regulated in highly cisplatin resistant cells

 

 

 

 

 

 

 

 

 

 

 

Loss of Mismatch Repair Can Lead to DNA Damage Tolerance

dnadamage tolerance

 

 

 

 

 

 

 

 

In the following Cancer Research paper Dr. Vaisman in the lab of Dr. Steve Chaney at North Carolina (and in collaboration with Dr. Tom Hamilton) describe how cisplatin resistance may arise from loss of mismatch repair and how oxaliplatin lesions are not recognized by the mismatch repair system.
Cancer Res. 1998 Aug 15;58(16):3579-85.

The role of hMLH1, hMSH3, and hMSH6 defects in cisplatin and oxaliplatin resistance: correlation with replicative bypass of platinum-DNA adducts.

Abstract

Defects in mismatch repair are associated with cisplatin resistance, and several mechanisms have been proposed to explain this correlation. It is hypothesized that futile cycles of translesion synthesis past cisplatin-DNA adducts followed by removal of the newly synthesized DNA by an active mismatch repair system may lead to cell death. Thus, resistance to platinum-DNA adducts could arise through loss of the mismatch repair pathway. However, no direct link between mismatch repair status and replicative bypass ability has been reported. In this study, cytotoxicity and steady-state chain elongation assays indicate that hMLH1 or hMSH6 defects result in 1.5-4.8-fold increased cisplatin resistance and 2.5-6-fold increased replicative bypass of cisplatin adducts. Oxaliplatin adducts are not recognized by the mismatch repair complex, and no significant differences in bypass of oxaliplatin adducts in mismatch repair-proficient and -defective cells were found. Defects in hMSH3 did not alter sensitivity to, or replicative bypass of, either cisplatin or oxaliplatin adducts. These observations support the hypothesis that mismatch repair defects in hMutL alpha and hMutS alpha, but not in hMutS beta, contribute to increased net replicative bypass of cisplatin adducts and therefore to drug resistance by preventing futile cycles of translesion synthesis and mismatch correction.

 

 

The following are slides I had co-prepared with my mentor Dr. Thomas C. Hamilton, Ph.D. of Fox Chase Cancer Center on DNA Mismatch Repair, Oxaliplatin and Ovarina Cancer.

edinborough2mmrtranslesion1

 

 

 

 

 

 

Multiple Platinum Analogs of Cisplatin (like Oxaliplatin )Had Been Designed to be Sensitive in MMR Deficient Tumors

edinborough2diffptanalogs

 

 

 

 

 

 

mmroxaliplatin

 

 

 

 

 

 

edinborough2ptanalogsresist

 

 

 

 

 

 

edinborough2relresistptanalogsdifflines

 

 

 

 

 

 

edinborough2msimlmh2refract

 

 

 

 

 

 

edinborough2gogoxaliplatintrial

 

 

 

 

 

 

 

Please see below video on 2015 Nobel Laureates and their work to elucidate the celluar DNA repair mechanisms.

Clinical genetics expert Kenneth Offit gives an overview of Lynch syndrome, a genetic disorder that can cause colon (HNPCC) and other cancers by defects in the MSH2 DNA mismatch repair gene. (View Video)

 

 

References

  1. Johnson, S. W. et al. Relationship between platinum-DNA adduct formation, removal, and cytotoxicity in cisplatin sensitive and resistant human ovarian cancer cells. Cancer Res 54, 5911-5916 (1994).
  2. Eastman, A. The formation, isolation and characterization of DNA adducts produced by anticancer platinum complexes. Pharmacology and Therapeutics 34, 155-166 (1987).
  3. Zhen, W. et al. Increased gene-specific repair of cisplatin interstrand cross-links in cisplatin-resistant human ovarian cancer cell lines. Molecular and Cellular Biology 12, 3689-3698 (1992).
  4. Durocher, D. & Jackson, S. P. DNA-PK, ATM and ATR as sensors of DNA damage: variations on a theme? Curr Opin Cell Biol 13, 225-231 (2001).
  5. el-Deiry, W. S. p21/p53, cellular growth control and genomic integrity. Curr Top Microbiol Immunol 227, 121-37 (1998).
  6. Ewen, M. E. & Miller, S. J. p53 and translational control. Biochim Biophys Acta 1242, 181-4 (1996).
  7. Gartel, A. L., Serfas, M. S. & Tyner, A. L. p21–negative regulator of the cell cycle. Proc Soc Exp Biol Med 213, 138-49 (1996).
  8. Chang, B. D. et al. p21Waf1/Cip1/Sdi1-induced growth arrest is associated with depletion of mitosis-control proteins and leads to abnormal mitosis and endoreduplication in recovering cells. Oncogene 19, 2165-70 (2000).
  9. Davies, N. P., Hardman, L. C. & Murray, V. The effect of chromatin structure on cisplatin damage in intact human cells. Nucleic Acids Res 28, 2954-2958 (2000).
  10. Vichi, P. et al. Cisplatin- and UV-damaged DNA lure the basal transcription factor TFIID/TBP. Embo J 16, 7444-7456 (1997).
  11. Xiao, G. et al. A DNA damage signal is required for p53 to activate gadd45. Cancer Res 60, 1711-9 (2000).

Other articles in this Open Access Journal on ChemoResistance Include:

Cancer Stem Cells as a Mechanism of Resistance

An alternative approach to overcoming the apoptotic resistance of pancreatic cancer

Mutation D538G – a novel mechanism conferring acquired Endocrine Resistance causes a change in the Estrogen Receptor and Treatment of Breast Cancer with Tamoxifen

Can IntraTumoral Heterogeneity Be Thought of as a Mechanism of Resistance?

Nitric Oxide Mitigates Sensitivity of Melanoma Cells to Cisplatin

Heroes in Medical Research: Barnett Rosenberg and the Discovery of Cisplatin

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Cancer Stem Cells as a Mechanism of Resistance

 

Curator: Stephen J. Williams, Ph.D.

The cancer stem-cell hypothesis proposes the existence of a subset of cells within a heterogeneous tumor cell population that have stem-cell like properties [1], and may be essential for the progression and metastases of epithelial malignancies, by providing a reservoir of cells that self-renew and differentiate into the bulk of the tumor [2]. The stem-cell hypothesis implies that similar genetic regulatory pathways might define critical stem-cell like functions, such as self-renewal and pluripotency, in both normal and cancer stem-cells. Indeed, cancer stem-cells have been identified in many tumor types, such as breast [3], pancreas [4] and ovarian [5], based on screening with cellular markers typically found in normal stem-cells such as CD44, ALDH1, and CD133 (reviewed in [2]). A number of studies have suggested that the expression of these stem-cell markers is correlated with poor prognosis [6-9]. The ability to identify and isolate these populations may have a significant impact on design of individualized therapies.

Great general posts and good review on this site about Cancer Stem Cells, their markers, and ability to target them with chemotherapy can be seen here.

In Focus: Identity of Cancer Stem Cells

In Focus: Targeting of Cancer Stem Cells

Stem Cells and Cancer

 

However, there has been growing acknowledgement of the ability of cancer stem cell populations to resist the cytotoxic effects of most chemotherapeutic agents, including cisplatin, topoisomerase inhibitors, DNA damaging agents, and even tyrosine kinase inhibitors (TKI). Indeed, some feel that intrinsic resistance to cytotoxic drugs may be a biological feature of cancer stem cells.

Definitions:

Acquired resistance: a resistance to a particular drug which results following continued exposure to said drug. Can take days (in cases of some TKIs) or months to develop. Acquired resistant cells lines are developed by exposure to increasing drug concentration over a time period (either intermittent exposure or continuous exposure)

Intrinsic resistance: a pre-existing resistance usually termed refractory where cancer cells THAT HAVE NOT BEEN EXPOSED to drug, do not respond to initial drug exposure. Can be seen experimentally in panels of unrelated cancer cells lines isolated from untreated patients which show no cytotoxicity to drug exposure in vitro.

Below is one of the first reports which described the drug resistant phenotype of cancer stem cells in an in vivo (mouse) model of breast cancer with videos.

Cancer Res. 2008 May 1;68(9):3243-50. doi: 10.1158/0008-5472.CAN-07-5480.

Cancer stem cells contribute to cisplatin resistance in Brca1/p53-mediated mouse mammary tumors.

Shafee N1, Smith CR, Wei S, Kim Y, Mills GB, Hortobagyi GN, Stanbridge EJ, Lee EY.

Author information

Abstract

The majority of BRCA1-associated breast cancers are basal cell-like, which is associated with a poor outcome. Using a spontaneous mouse mammary tumor model, we show that platinum compounds, which generate DNA breaks during the repair process, are more effective than doxorubicin in Brca1/p53-mutated tumors. At 0.5 mg/kg of daily cisplatin treatment, 80% primary tumors (n = 8) show complete pathologic response. At greater dosages, 100% show complete response (n = 19). However, after 2 to 3 months of complete remission following platinum treatment, tumors relapse and become refractory to successive rounds of treatment. Approximately 3.8% to 8.0% (mean, 5.9%) of tumor cells express the normal mammary stem cell markers, CD29(hi)24(med), and these cells are tumorigenic, whereas CD29(med)24(-/lo) and CD29(med)24(hi) cells have diminished tumorigenicity or are nontumorigenic, respectively. In partially platinum-responsive primary transplants, 6.6% to 11.0% (mean, 8.8%) tumor cells are CD29(hi)24(med); these populations significantly increase to 16.5% to 29.2% (mean, 22.8%; P < 0.05) in platinum-refractory secondary tumor transplants. Further, refractory tumor cells have greater colony-forming ability than the primary transplant-derived cells in the presence of cisplatin. Expression of a normal stem cell marker, Nanog, is decreased in the CD29(hi)24(med) populations in the secondary transplants. Top2A expression is also down-regulated in secondary drug-resistant tumor populations and, in one case, was accompanied by genomic deletion of Top2A. These studies identify distinct cancer cell populations for therapeutic targeting in breast cancer and implicate clonal evolution and expansion of cancer stem-like cells as a potential cause of chemoresistance.

Please Watch Videos

 

Below is a curation of talks and abstracts from the 2015 Annual AACR Meeting in Philadelphia, PA.

The Talk by Dr. Cheresh is an example of this school of thought; that inducing cancer cell stemness can result in development of drug resistance, in this case to a TKI. (For a press release on this finding see here.)

SY27-04: Induction of cancer stemness and drug resistance by EGFR blockade
Tuesday, Apr 21, 2015, 12:00 PM -12:15 PM
David A. Cheresh. UCSD Moores Cancer Center, La Jolla, CA

SY27-04  
 
Presentation Title: Induction of cancer stemness and drug resistance by EGFR blockade
Presentation Time: Tuesday, Apr 21, 2015, 12:00 PM -12:15 PM
Abstract Body: Tumor drug resistance is often accompanied by genetic and biological changes in the tumor cell population reflecting the acquisition of a stem-like state. However, it is not clear whether cancer therapies select for the growth of drug resistance cancer stem cells and/or directly induce the reprograming of tumor cells to a cancer stem-like, drug resistance state. We provide evidence that breast, pancreas and lung carcinomas in the presence of prolonged exposure to EGFR inhibitors undergo an epigenetic reprogramming resulting in a drug resistant stem-like tumor population expressing the cell surface marker CD61 (b3 integrin). In fact, CD61 in the context of KRAS, is necessary and sufficient to account for drug resistance, tumor initiation, self-renewal and expression of the pluripotent genes Oct 4 and Nanog. Once expressed, CD61 in the unligated state recruits KRAS to the plasma membrane leading to the activation of RalB, TBK1 and c-Rel driving both stemness and EGFR inhibitor resistance. Pharmacological targeting this pathway with drugs such as bortezomib or revlimid not only reverses stemness but resensitizes these epithelial tumors to EGFR inhibition. This epigenetic pathway can also be initiated by range of cellular stresses found within the tumor microenvironment such as hypoxia, nutrient deprivation, low pH, and oxidative stress. In normal tissues CD61 is induced during tissue remodeling and repair. For example, CD61 was found to be critical for mammary gland remodeling during pregnancy and as a mediator of pathological neovascularization. Together these findings reveal a stress-induced epigenetic pathway characterized by the upregulation of CD61 that promotes the remodeling of normal tissues but in tumors contributes to EGFR inhibitor resistance and tumor progression.

 

http://cancerres.aacrjournals.org/gca?gca=canres%3B75%2F15_Supplement%2F4&gca=canres%3B75%2F15_Supplement%2F6&gca=canres%3B75%2F15_Supplement%2F19&gca=canres%3B75%2F15_Supplement%2F24&gca=canres%3B75%2F15_Supplement%2F48&gca=canres%3B75%2F15_Supplement%2F54&gca=canres%3B75%2F15_Supplement%2F57&gca=canres%3B75%2F15_Supplement%2F88&gca=canres%3B75%2F15_Supplement%2F90&gca=canres%3B75%2F15_Supplement%2F97&allch=&submit=Go

Selected Abstracts

  1. Abstract 1
  2. Molecular and Cellular Biology – Poster Presentations – Proffered Abstracts – Poster Presentations – Cell Death Mechanisms: Abstract 4: ABT-263 is effective in a subset of non-small cell lung cancer cell lines
    • Aoi Kuroda,
    • Keiko Ohgino,
    • Hiroyuki Yasuda,
    • Junko Hamamoto,
    • Daisuke Arai,
    • Kota Ishioka,
    • Tetsuo Tani,
    • Shigenari Nukaga,
    • Ichiro Kawada,
    • Katsuhiko Naoki,
    • Kenzo Soejima,
    • and Tomoko Betsuyaku

Cancer Res August 1, 2015 75:4; doi:10.1158/1538-7445.AM2015-4

  1. Abstract 2
  2. Molecular and Cellular Biology – Poster Presentations – Proffered Abstracts – Poster Presentations – Cell Death Mechanisms: Abstract 6: Quantitative assessment of BCL-2:BIM complexes as a pharmacodynamic marker for venetoclax (ABT-199)
    • Sha Jin,
    • Paul Tapang,
    • Donald J. Osterling,
    • Wenqing Gao,
    • Daniel H. Albert,
    • Andrew J. Souers,
    • Joel D. Leverson,
    • Darren C. Phillips,
    • and Jun Chen

Cancer Res August 1, 2015 75:6; doi:10.1158/1538-7445.AM2015-6

  1. Molecular and Cellular Biology – Poster Presentations – Proffered Abstracts – Poster Presentations – Cell Death Mechanisms: Abstract 24: The phosphorylation of p53 at serine 46 is essential to induce cell death through palmdelphin in response to DNA damage
    • Nurmaa Khund Dashzeveg and
    • Kiyotsugu Yoshida

Cancer Res August 1, 2015 75:24; doi:10.1158/1538-7445.AM2015-24

  1. Abstract 5
  2. Molecular and Cellular Biology – Poster Presentations – Proffered Abstracts – Poster Presentations – Cell Signaling in Cancer 1: Abstract 48: Identification of a novel binding protein playing a critical role in HER2 activation in lung cancer cells
    • Tomoaki Ohtsuka,
    • Masakiyo Sakaguchi,
    • Katsuyoshi Takata,
    • Shinsuke Hashida,
    • Mototsugu Watanabe,
    • Ken Suzawa,
    • Yuho Maki,
    • Hiromasa Yamamoto,
    • Junichi Soh,
    • Hiroaki Asano,
    • Kazunori Tsukuda,
    • Shinichiro Miyoshi,
    • and Shinichi Toyooka

Cancer Res August 1, 2015 75:48; doi:10.1158/1538-7445.AM2015-48

  1. Abstract 1 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Cell Death Mechanisms

Abstract 4: ABT-263 is effective in a subset of non-small cell lung cancer cell lines

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

Rationale:

ABT-263 (Navitoclax) is one of the BH3 mimetics targeting anti-apoptotic B-cell lymphoma-2 (Bcl-2) family proteins such as Bcl-2, Bcl-XL, and Bcl-w, thereby inducing apoptosis. It has been reported that the response to ABT-263 is associated with expressions of myeloid cell leukemia-1 (Mcl-1), an anti-apoptotic protein. Given its effectiveness as a single agent in preclinical studies, ABT-263 is currently being evaluated in clinical trials for small cell lung cancer (SCLC) and leukemia. However, the efficacy of ABT-263 in non-small cell lung cancer (NSCLC) has not been fully evaluated. We examined the effect of ABT-263 on cell proliferation of NSCLC cell lines and investigated the underlying mechanisms.

Methods:

The following 9 NSCLC cell lines were examined: SK-LU-1, A549, H358, Calu3, H3122, H1975, H460, H441, and BID007. The effects of ABT-263 in NSCLC cell lines were evaluated by MTS assay. Apoptosis was examined by flowcytometry using staining for annexin V and propidium iodide (PI), and also western blotting for cleaved PARP. Quantitative RT-PCR was carried out to assess the mRNA expression levels of anti-apoptotic genes and pro-apoptotic genes. Immunoprecipitation and western blotting were performed to compare the levels of anti-apoptotic and pro-apoptotic proteins between the sensitive and resistant cell lines. In addition, knockdown of Mcl-1 was performed by siRNA.

Results:

By screening 9 NSCLC cell lines using MTS assay, we found Calu3 and BID007were sensitive to ABT-263. We also confirmed that apoptosis was induced only in the ABT-263 sensitive lines but not in the ABT-263 resistant cell lines after ABT-263 treatment. However, the expression levels of Bcl-2 family proteins, including Mcl-1, did not differ significantly among the ABT-263 sensitive and resistant cell lines. Unlike the results in previous reports regarding SCLC, Mcl-1 was not decreased in the sensitive cell lines. The ABT-263 resistant cell lines became sensitive to ABT-263 after knockdown of Mcl-1 by siRNA, while the ABT-263 sensitive cell lines maintained the same sensitivity.

Conclusion:

We found that Calu3 and BID007 were sensitive to ABT-263. In the sensitive NSCLC cell lines, ABT-263 induces apoptosis irrespective of Mcl-1 expression levels.

Citation Format: Aoi Kuroda, Keiko Ohgino, Hiroyuki Yasuda, Junko Hamamoto, Daisuke Arai, Kota Ishioka, Tetsuo Tani, Shigenari Nukaga, Ichiro Kawada, Katsuhiko Naoki, Kenzo Soejima, Tomoko Betsuyaku. ABT-263 is effective in a subset of non-small cell lung cancer cell lines. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4. doi:10.1158/1538-7445.AM2015-4

    • ©2015 American Association for Cancer Research.
  1. Abstract 2 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Cell Death Mechanisms

Abstract 6: Quantitative assessment of BCL-2:BIM complexes as a pharmacodynamic marker for venetoclax (ABT-199)

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

The BCL-2-selective inhibitor venetoclax (ABT-199) binds with high affinity to the BH3-binding groove of BCL-2, thereby competing for binding with the BH3-only protein BIM (Souers et al., 2013). Venetoclax is currently being evaluated in clinical trials for CLL, AML, multiple myeloma and NHL. To facilitate these studies, we developed and validated a 384-well electrochemiluminescent ELISA (MSD, Gaithersburg, MD,USA) that quantifies expression of BCL-2, BCL-XL, and MCL-1protein alone or in complex with BIM. We subsequently quantified expression of BCL-2 and BCL-2:BIM complexes in 16 hematologic tumor cell lines. We found the EC50 of venetoclax in these tumor cell lines to correlate strongly with baseline BCL-2:BIM complex levels. This correlation was superior to the correlation between venetoclax EC50 and absolute BCL-2 expression. We also applied the assay to measure disruption of BCL-2:BIM complexes in vivo. Treatment of the Non-Hodgkin’s Lymphoma (NHL) xenograft model SU-DHL-4 with a BCL-2-selective inhibitor resulted in disruption of tumor BCL-2:BIM complexes that aligned with serum and tumor concentrations of inhibitor. Collectively, these data demonstrate that quantifying BCL-2:BIM complexes offers an accurate means of assessing target engagement by venetoclax and, potentially, predicting its efficacy. The utility of this assay is currently being assessed in clinical trials.

Citation Format: Sha Jin, Paul Tapang, Donald J. Osterling, Wenqing Gao, Daniel H. Albert, Andrew J. Souers, Joel D. Leverson, Darren C. Phillips, Jun Chen. Quantitative assessment of BCL-2:BIM complexes as a pharmacodynamic marker for venetoclax (ABT-199). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 6. doi:10.1158/1538-7445.AM2015-6

    • ©2015 American Association for Cancer Research.
  1. Abstract 3 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Cell Death Mechanisms

Abstract 19: Antitumor activity of selective inhibitors of XPO1/CRM1-mediated nuclear export in diffuse malignant peritoneal mesothelioma: the role of survivin

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

Survivin, which is highly expressed and promotes cell survival in diffuse malignant peritoneal mesothelioma (DMPM), exclusively relies on the nuclear exportin 1 (XPO1/CRM1) to be released in the cytoplasm and perform its anti-apoptotic function. Here, we explored the efficacy of selective inhibitors of nuclear export (SINEs) in patient-derived DMPM preclinical models. Exposure to individual SINE (KPT-251, KPT-276, KPT-330) was able to induce a time- and dose-dependent inhibition of the growth of two DMPM cell lines without affecting normal cell proliferation. Such a cell growth inhibition was preceded by a decline in the nuclear XPO1/CRM1 levels and an increase in the nuclear accumulation of its cargo proteins p53 and p21, which led to a cell cycle arrest at G1-phase. Our results also indicated that survivin is an essential component of the downstream signaling pathway of XPO1/CRM1 inhibition in DMPM cells. In fact, in both cell lines, exposure to SINEs led to a time-dependent reduction of cytoplasmic survivin levels and, after an initial survivin nuclear accumulation, also to a progressive decrease in the nuclear protein abundance, through the ubiquitin-proteasomal degradation pathway, leading to the complete depletion of total survivin levels. In both DMPM cell models, according to survivin anti-apoptotic activity, drug-induced reduction of cytoplasmic survivin levels correlated with the onset of caspase-dependent apoptosis. We further observed that SINEs can be combined with other survivin inhibitors, such as the survivin suppressant YM155 to achieve enhanced growth inhibition in DMPM cells. Initial in vivo experiments with orally administered KPT-251, KPT-276 and the orally available, clinical stage KPT-330 (selinexor) indicated that each compound was able to significantly reduce the growth of early-stage subcutaneous DMPM xenografts. Interestingly, additional experiments carry out with selinexor demonstrated that the compound was also able to inhibit the growth of late-stage subcutaneous DMPM xenografts in nude mice. Most importantly, oral administration of selinexor to SCID mice reduced the growth of orthotopic DMPM xenografts, which properly recapitulate the dissemination pattern in the peritoneal cavity of human DMPM and, for this reason, represent a valuable model for investigating novel therapeutic approaches for the disease. Consistent with an important role of survivin as a determinant of anti-cancer activity of SINE compounds, a reduction of the protein expression was observed in tumor specimens obtained from selinexor treated mice. Overall, our results (i) demonstrate a marked efficacy of SINEs in DMPM preclinical models, which is, at least in part, dependent on the interference with survivin intracellular distribution and function, and (ii) suggest SINE-mediated XPO1/CRM1 inhibition as a novel therapeutic option for the disease.

Citation Format: Nadia Zaffaroni, Michelandrea De Cesare, Denis Cominetti, Valentina Doldi, Alessia Lopergolo, Marcello Deraco, Paolo Gandellini, Yosef Landesman, Sharon Friedlander, Michael G. Kauffman, Sharon Shacham, Marzia Pennati. Antitumor activity of selective inhibitors of XPO1/CRM1-mediated nuclear export in diffuse malignant peritoneal mesothelioma: the role of survivin. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 19. doi:10.1158/1538-7445.AM2015-19

    • ©2015 American Association for Cancer Research.
  1. Abstract 4 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Cell Death Mechanisms

Abstract 24: The phosphorylation of p53 at serine 46 is essential to induce cell death through palmdelphin in response to DNA damage

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

Tumor suppressor p53 plays a pivotal role in cell cycle arrest, DNA repair, and apoptosis in response to DNA damage. Promoter selectivity of p53 depends mainly on post-translational modification. Notably, the apoptotic function of p53 is related to its phosphorylation at serine-46 (ser46) to promote pro-apoptotic genes. However, little is known about the pro-apoptotic genes induced by Ser46 phosphorylation. Our research achieved to investigate the pro-apoptotic genes induced by p53 in a phospho-ser46-specific manner using microarray and ChIP sequencing in human cancer cell lines. As a result, palmdelphin (PALMD), an isoform of paralemmin protein, was strongly elicited from the phosphorylation of ser46. The mRNA and protein expression of PALMD increased only in wild type p53 transfected cells, but not in ser46-mutated cells. Importantly, PALMD moved to the nucleus in response to DNA damage and the apoptotic function of PALMD was tightly exerted with localization into nucleus. Interestingly, down-regulation of PALMD by siRNA resulted in necroptosis-like cell death through ATP depletion. Moreover, we found vimentin as a PALMD interacting protein and the depletion of vimentin increased PALMD level to accelerate apoptosis. These results demonstrate that p53 regulates cell death fate (apoptosis or necroptosis-like cell death) through promoting PALMD expression in a phospho-ser46-specific manner in response to DNA damage.

Citation Format: Nurmaa Khund Dashzeveg, Kiyotsugu Yoshida. The phosphorylation of p53 at serine 46 is essential to induce cell death through palmdelphin in response to DNA damage. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 24. doi:10.1158/1538-7445.AM2015-24

    • ©2015 American Association for Cancer Research.
  1. Abstract 5 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Cell Signaling in Cancer 1

Abstract 48: Identification of a novel binding protein playing a critical role in HER2 activation in lung cancer cells

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

Human epidermal growth factor receptor 2 (HER2) is a member of epidermal growth factor receptor (EGFR) family. Previous studies have revealed that many kinds of malignant tumors have genetic mutations or amplification of HER2, indicating that HER2 alterations are oncogenic. Many kinds of HER2 targeted therapies are effective to HER2 positive tumors, but those treated tumors often get resistance to drugs. Thus, to elucidate HER2 related pathway in cancer biology is important to develop new therapeutic strategy for cancers.

Recently, we newly identified a protein X (a temporary name) as a novel binding protein to HER2 with immunoprecipitation and following LC-Ms/Ms analysis. The protein generally expressed in lung and breast cancers at remarkable level.

We constructed plasmid vectors carrying wild type HER2 and gene X. These vectors were simultaneously introduced to HEK293T cells to examine the binding ability of protein X and HER2 as well as the effect of gene X on HER2-mediated signal-transduction pathway. The approach clearly showed that the expression of gene X, resulted in phosphorylation of HER2 and subsequent activation of oncogenic effector molecules.

We next constructed several kinds of gene X-truncated variants and subjected to the binding assay to look for the binding domain of gene X to HER2. The analysis showed that N-terminal head domain of gene X was essential for the HER2 binding. This domain has an ability to induce HER2 phosphorylation and subsequent activation of the effector kinase, ERK.

In conclusion, we found that gene X is a novel binding protein to HER2 and has a role in HER2 activation.

Citation Format: Tomoaki Ohtsuka, Masakiyo Sakaguchi, Katsuyoshi Takata, Shinsuke Hashida, Mototsugu Watanabe, Ken Suzawa, Yuho Maki, Hiromasa Yamamoto, Junichi Soh, Hiroaki Asano, Kazunori Tsukuda, Shinichiro Miyoshi, Shinichi Toyooka. Identification of a novel binding protein playing a critical role in HER2 activation in lung cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 48. doi:10.1158/1538-7445.AM2015-48

    • ©2015 American Association for Cancer Research.
  1. Abstract 6 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Cell Signaling in Cancer 1

Abstract 54: Ezrin enhances signaling and nuclear translocation of the epidermal growth factor receptor in non-small cell lung cancer cells

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

The cytoskeletal cross linker protein ezrin is a member of the ezrin-radixin-moesin (ERM) family and plays important roles not only in cell motility, cell adhesion, and apoptosis, but also in various cell-signaling pathways. Ezrin interacts with EGFR in the cell membrane and involves in cell motility events, but little is known about the effects of this interaction on the EGFR signaling pathway. We investigated the role of Ezrin in EGFR signaling and nuclear trafficking in non-small cell lung cancer (NSCLC) cell lines. The ligand induced interaction between Ezrin and EGFR was evaluated by immunoprecipitation (IP) and immunofluorescence (IF) in H292 and A549 cells. Ezrin levels were reduced using siRNA in these two cell lines. Downstream signaling protein phosphorylation and nuclear localization of EGFR were detected after EGF treatment. Expressions of nuclear EGFR target genes were evaluated by qPCR. Endogenous Ezrin was found in a complex with EGFR in IP and IF. When Ezrin protein expression was inhibited, phosphorylation levels of EGFR at Y1068, Y1101 and Y845 were reduced as well as phosphorylation levels of downstream signaling pathway proteins ERK and STAT3. Cell fractionation revealed that EGFR nuclear translocation after EGF treatment significantly reduced in Ezrin-knockdown cells. Further, mRNA levels of EGFR target genes AuroraK-A, COX2, Cyclin D1 and iNOS were decreased in Ezrin-knockdown A549 cells. Small molecule ezrin inhibitors showed strong synergy with EGFR inhibitors in cytotoxicity assays. These results suggest that Ezrin has a role as an enhancer in the EGFR pathway and targeting ezrin may potentiate anti-EGFR based therapies in NSCLC.

Citation Format: Yasemin Saygideger Kont, Haydar Celik, Hayriye V. Erkizan, Tsion Minas, Jenny Han, Jeffrey Toretsky, Aykut Uren. Ezrin enhances signaling and nuclear translocation of the epidermal growth factor receptor in non-small cell lung cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 54. doi:10.1158/1538-7445.AM2015-54

    • ©2015 American Association for Cancer Research.
  1. Abstract 7 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Cell Signaling in Cancer 1

Abstract 57: Substrates of protein kinase C drive cell rac1-dependent motility

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

This laboratory has identified and/or characterized substrates of PKC that upon phosphorylation give rise to motility, an aspect of metastasis. By use of the traceable kinase method, we discovered that alpha-tubulin and Cdc42 effector protein-4 (CEP4) are PKC substrates. Phosphorylation of alpha-tubulin stimulates its incorporation into microtubules (MTs), consequently increasing the stability and prolonged growth of MTs and leading to the activation of the small GTPase Rac1. CEP4 undergoes phosphorylation by PKC that results in its release from Cdc42, whereupon CEP4 binds a guanine nucleotide exchange factor (GEF) that in turn activates Rac1 GTPase. These results imply that Rac1 acts as a node in pathways driven by phosphorylated PKC substrates. Since translocation of IQGAP to the membrane is known to be promoted by Rac1, a role is explored in non-transformed human MCF-10A cells that express a specific phospho-mimetic mutant substrate. In addition, the phospho-mimetic mutant for each substrate expressed in human metastatic MDA-MB-231 cells produces different morphologies in 3-D growth assays. This research is being supported by NIH CA125632.

Citation Format: Susan A. Rotenberg, Xin Zhao, Shatarupa De. Substrates of protein kinase C drive cell rac1-dependent motility. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 57. doi:10.1158/1538-7445.AM2015-57

    • ©2015 American Association for Cancer Research.
  1. Abstract 8 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Deregulation of Gene Expression in Prostate Cancer and Sarcoma

Abstract 88: The Nkx3.1 homeobox gene maintains prostatic identity while its loss leads to prostate cancer initiation

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

Background

Maintenance of epithelial cell identity is tightly coordinated by tissue-specific gene expression programs, which are often deregulated during tumorigenesis. The homeodomain-containing transcription factor, Nkx3.1, is a key regulator of normal prostatic development and is frequently lost at early stages of prostate cancer initiation. In this study, we aim to elucidate detailed mechanisms governing Nkx3.1-driven maintenance of prostate identity and how deregulation of such can lead to prostate tumorigenesis.

Models and Methods

We evaluated the consequences of Nkx3.1 loss or gain of function in vivo using genetically-engineered mouse models and cell-recombination assays. RNA sequencing was performed to generate gene expression profiles, which were analyzed using Gene Set Enrichment analysis (GSEA), and validated by quantitative real-time PCR. In parallel, protein expression was assessed by immunofluorescence and western blot. Immunoprecipitation (IP) and chromatin-immunoprecipitation (ChIP) assays were performed using RWPE1 prostate epithelial cells.

Results

Here, we show that loss of function of Nkx3.1 leads to the progressive down-regulation of a prostate-specific gene expression program and to aberrant expression of genes that are not typically expressed in the prostate epithelium. Conversely, gain of function of Nkx3.1 in non-prostatic epithelium leads to the acquisition of a prostate-like morphology and expression of prostate-related genes. Our findings indicate that the underlying mechanism by which Nkx3.1 promotes prostatic identity is via epigenetic regulation of gene expression. In particular, we show that Nkx3.1 interacts with the histone methyl-transferase complex G9a/Glp. Finally, we demonstrate that this interaction is necessary for maintenance of prostate identity in vivo and that Nkx3.1 and G9a cooperate to control expression of genes that coordinate prostatic epithelial integrity.

Conclusions

Our results suggest that Nkx3.1 promotes prostatic identity by interacting with histone modifying enzymes to coordinate the expression of prostate-specific genes and that the loss of this function results in a failure to maintain prostate identity associated with early stages of prostate tumorigenesis.

Citation Format: Clémentine Le Magnen, Aditya Dutta, Cory Abate-Shen. The Nkx3.1 homeobox gene maintains prostatic identity while its loss leads to prostate cancer initiation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 88. doi:10.1158/1538-7445.AM2015-88

    • ©2015 American Association for Cancer Research.
  1. Abstract 9 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Deregulation of Gene Expression in Prostate Cancer and Sarcoma

Abstract 90: K63-linked JARID1B ubiquitination by TRAF6 contributes to aberrant elevation of JARID1B in prostate cancer

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

Aberrant elevation of JARID1B and histone H3 Lys4 trimethylations (H3K4me3) is frequently observed in many diseases including prostate cancer (PCa), yet the mechanisms on the regulations of JARID1B and H3K4me3 through epigenetic modifications still remain poorly understood. In this study we performed immunohistochemistry staining, immunofluorescence imaging, immunoprecipitation, shRNA and Western blotting analysis in mouse embryonic fibroblasts (MEFs), mouse models, and cultured human prostate cancer cells. As a result, we discovered that SKP2 modulates JARID1B and H3K4me3 levels in vitro in PTEN null prostate cancer cells and in vivo in Pten/Trp53 mouse models. We demonstrated that levels of SKP2, JARID1B and H3K4me3 are strikingly elevated in vitro and in vivo when both PTEN and P53 are inactivated. Importantly, SKP2 inactivation resulted in a reduction of cell growth, cell migration and malignant transformation of Pten/Trp53 double null MEFs, and further restrained prostate tumorigenesis of Pten/Trp53 mutant mice. Mechanistically, JARID1B is ubiquitinated by E3 ligase TRAF6 through the K63-linkage in prostate cancer cells. Interestingly, SKP2 contributes to JARID1B ubiquitination machinery as a non-E3 ligase regulator by decreasing TRAF6-mediated ubiquitination of JARID1B. SKP2 deficiency resulted in an increase of JARID1B ubiquitination and in turn a reduction of H3K4me3, and induced senescence through JARID1B accumulation in nucleoli of PCa cells and prostate tumors of mice. Furthermore, we showed that the aberrant levels of SKP2, JARID1B, and H3K4me3 are associated with malignant features of castration-resistant prostate cancer (CRPC) in mice. Overall, our findings reveal a novel network of SKP2- JARID1B, and targeting SKP2 and JARID1B may be a potential strategy for PCa control.

Citation Format: Wenfu Lu, Shenji Liu, Bo Li, Yingqiu Xie, Christine Adhiambo, Qing Yang, Billy R. Ballard, Keiichi I. Nakayama, Robert J. Matusik, Zhenbang Chen. K63-linked JARID1B ubiquitination by TRAF6 contributes to aberrant elevation of JARID1B in prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 90. doi:10.1158/1538-7445.AM2015-90

    • ©2015 American Association for Cancer Research.
  1. Abstract 10 of 10Molecular and Cellular Biology / Poster Presentations – Proffered Abstracts / Poster Presentations – Histone Methylation and Acetylation

Abstract 97: CARM1 preferentially methylates H3R17 over H3R26 through a random kinetic mechanism

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA

CARM1 (PRMT4) is a type I arginine methyltransferase involved in the regulation of transcription, pre-mRNA splicing, cell cycle progression and the DNA damage response. Overexpression of CARM1 has been implicated in breast, prostate, and colorectal cancers. Since CARM1 appears to be a good target for the development of therapies against these cancers, we studied the substrate specificity and kinetic mechanism of the full-length human enzyme. CARM1 has been shown to methylate both residues R17 and R26 of histone H3. Substrate specificity was examined by testing CARM1 activity with several H3-based peptide substrates using a radiometric assay. Comparison of kcat/KM values reveal that methylation of H3R17 is preferred over H3R26. An R17/R26K peptide produced 8-fold greater kcat/KM value compared to the corresponding R17K/R26 peptide. These effects are KM-driven as kcat values remain relatively constant for the peptides tested. Shortening the peptide at the C-terminus by 5 amino acid residues greatly reduced the specificity (16-24-fold), demonstrating the contribution of distal residues to substrate binding. In contrast, adding residues to the N-terminus of the shortened peptide had a negative effect on activity. CARM1 displays little preference for monomethylated over unmethylated H3R17 (2-5-fold by kcat/KM) suggesting that it operates through a distributive mechanism. Previous crystallographic studies with mouse CARM1 showed that part of the substrate binding groove was formed by cofactor binding, thereby suggesting an ordered kinetic mechanism (Yue et al., EMBO J., 2007). Our results from dead-end and product inhibition studies performed with human CARM1, however, are consistent with a random kinetic mechanism. SAH and sinefungin demonstrate competitive inhibition with respect to SAM and produced noncompetitive inhibition patterns with respect to peptide. Both dimethylated R17 product peptide and dead-end R17K peptide exhibited noncompetitive inhibition patterns with respect to SAM. Furthermore, binding of SAM and peptide substrates were shown to be independent of each other in initial velocity experiments where both substrates were varied. Together, these results elucidate the kinetic mechanism of CARM1 and highlight elements important for binding affinity.

Citation Format: Suzanne L. Jacques, Katrina P. Aquino, Jodi Gureasko, P Ann Boriack-Sjodin, Robert A. Copeland, Thomas V. Riera. CARM1 preferentially methylates H3R17 over H3R26 through a random kinetic mechanism. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 97. doi:10.1158/1538-7445.AM2015-97

    • ©2015 American Association for Cancer Research.

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