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Glypican-1 identifies cancer exosomes

Larry H. Bernstein, MD, FCAP, Curator

LPBI

Glypican-1 identifies cancer exosomes and detects early pancreatic cancer

Sonia A. MeloLinda B. LueckeChristoph KahlertAgustin F. FernandezSeth T. GammonJudith Kaye, et al.

Nature (09 July 2015); 523: 177–182     http://dx.doi.org:/10.1038/nature14581

Most cells shed so-called extracellular vesicles or exosomes consisting of proteins and nucleic acids enclosed in phospholipid bilayers. Exosomes derived from cancer cells can be isolated.

Exosomes are lipid-bilayer-enclosed extracellular vesicles that contain proteins and nucleic acids. They are secreted by all cells and circulate in the blood. Specific detection and isolation of cancer-cell-derived exosomes in the circulation is currently lacking. Using mass spectrometry analyses, we identify a cell surface proteoglycan, glypican-1 (GPC1), specifically enriched on cancer-cell-derived exosomes. GPC1+ circulating exosomes (crExos) were monitored and isolated using flow cytometry from the serum of patients and mice with cancer. GPC1+ crExos were detected in the serum of patients with pancreatic cancer with absolute specificity and sensitivity, distinguishing healthy subjects and patients with a benign pancreatic disease from patients with early- and late-stage pancreatic cancer. Levels of GPC1+ crExos correlate with tumour burden and the survival of pre- and post-surgical patients. GPC1+ crExos from patients and from mice with spontaneous pancreatic tumours carry specific KRAS mutations, and reliably detect pancreatic intraepithelial lesions in mice despite negative signals by magnetic resonance imaging. GPC1+ crExos may serve as a potential non-invasive diagnostic and screening tool to detect early stages of pancreatic cancer to facilitate possible curative surgical therapy.

Figure 1: GPC1 is present on cancer exosomes.

GPC1 is present on cancer exosomes.

a, Venn diagram of proteins from NIH/3T3 (blue), MCF10A (red), HDF (green), E10 (yellow) and MDA-MB-231 (purple) exosomes. In total, 48 proteins were exclusively detected in MDA-MB-231 exosomes (n = 3 protein samples,…

Figure 2: GPC1+ crExos are a non-invasive biomarker for pancreatic cancer.

GPC1+ crExos are a non-invasive biomarker for pancreatic cancer.

a, Percentage of GPC1+crExo beads in healthy donors, patients with breast cancer and patients with PDAC (analysis of variance (ANOVA), post-hoc Tamhane T2, ****P < 0.0001). b, Frequency ofKRAS mutation in 47 tumours…

Figure 3: Levels of circulating GPC1+exosomes inform pancreatic cancer resection outcome.

Levels of circulating GPC1+ exosomes inform pancreatic cancer resection outcome.

a, Longitudinal blood collection pre- and post-operatively (day 7). b, Percentage of GPC1+crExo beads from patients with BPD (n = 4), PCPL (n = 4) or PDAC (n = 29) (paired two-tailed Student’s t-test, **P < 0.01, ****P < 0.0001). Data a…

Cancer: Diagnosis by extracellular vesicles

Nature (09 July 2015); 523: 161–162.   http://dx.doi.org:/10.1038/nature14626

The detection of a single molecule anchored to circulating extracellular vesicles allows late-stage pancreatic cancer to be identified from just one drop of a patient’s blood. See Article p.177

ReferencesAuthor information

  1. Melo, S. A. et al. Nature 523, 177182 (2015).    Article
  2. Kleeff, J. et al. J. Clin. Invest. 102, 16621673 (1998).

3.   Aikawa, T. et al. J. Clin. Invest. 118, 8999 (2008).

4.  Whipple, C. A., Young, A. L. & Korc, M. Oncogene 31, 25352544 (2012).

  • Kim, J. W. et al. Clin. Cancer Res. 11, 10101020 (2005).
  • Zhou, H. et al. Kidney Int. 70, 18471857 (2006).
  • Skog, J. et al. Nature Cell Biol. 10, 14701476 (2008).
  • Peinado, H. et al. Nature Med. 18, 883891 (2012).
  • Logozzi, M. et al. PLoS ONE 4, e5219 (2009).
  • Jakobsen, K. R. et al. J. Extracell. Vesicles 4, 26659 (2015).
  • Madhavan, B. et al. Int. J. Cancer 136, 26162627 (2015).
  • Trams, E. G., Lauter, C. J., Salem, N. Jr & Heine, U. Biochim. Biophys. Acta 645, 6370(1981).
  • Johnstone, R. M., Adam, M., Hammond, J. R., Orr, L. & Turbide, C. J. Biol. Chem. 262,94129420 (1987).
  • Gould, S. J. & Raposo, G. J. Extracell. Vesicles 2, 20389 (2013).

Oxidative stress inhibits distant metastasis by human melanoma cells

Elena PiskounovaMichalis AgathocleousMalea M. MurphyZeping HuSara E. HuddlestunZhiyu Zhao, et al.

Nature 14 Oct 2015      http://dx.doi.org:/10.1038/nature15726

Solid cancer cells commonly enter the blood and disseminate systemically, but are highly inefficient at forming distant metastases for poorly understood reasons. Here we studied human melanomas that differed in their metastasis histories in patients and in their capacity to metastasize in NOD-SCID-Il2rg−/− (NSG) mice. We show that melanomas had high frequencies of cells that formed subcutaneous tumours, but much lower percentages of cells that formed tumours after intravenous or intrasplenic transplantation, particularly among inefficiently metastasizing melanomas. Melanoma cells in the blood and visceral organs experienced oxidative stress not observed in established subcutaneous tumours. Successfully metastasizing melanomas underwent reversible metabolic changes during metastasis that increased their capacity to withstand oxidative stress, including increased dependence on NADPH-generating enzymes in the folate pathway. Antioxidants promoted distant metastasis in NSG mice. Folate pathway inhibition using low-dose methotrexate, ALDH1L2 knockdown, or MTHFD1 knockdown inhibited distant metastasis without significantly affecting the growth of subcutaneous tumours in the same mice. Oxidative stress thus limits distant metastasis by melanoma cells in vivo.

Lymph node-independent liver metastasis in a model of metastatic colorectal cancer

Ida B. EnquistZinaida GoodAdrian M. JubbGermaine FuhXi WangMelissa R. JunttilaErica L. Jackson & Kevin G. Leong

Nature Communications  26 Mar 2014; 3530(5)    http://dx.doi.org:/10.1038/ncomms4530

Deciphering metastatic routes is critically important as metastasis is a primary cause of cancer mortality. In colorectal cancer (CRC), it is unknown whether liver metastases derive from cancer cells that first colonize intestinal lymph nodes, or whether such metastases can form without prior lymph node involvement. A lack of relevant metastatic CRC models has precluded investigations into metastatic routes. Here we describe a metastatic CRC mouse model and show that liver metastases can manifest without a lymph node metastatic intermediary. Colorectal tumours transplanted onto the colonic mucosa invade and metastasize to specific target organs including the intestinal lymph nodes, liver and lungs. Importantly, this metastatic pattern differs from that observed following caecum implantation, which invariably involves peritoneal carcinomatosis. Anti-angiogenesis inhibits liver metastasis, yet anti-lymphangiogenesis does not impact liver metastasis despite abrogating lymph node metastasis. Our data demonstrate direct hematogenous spread as a dissemination route that contributes to CRC liver malignancy.

Comprehensive models of human primary and metastatic colorectal tumors in immunodeficient and immunocompetent mice by chemokine targeting

Huanhuan Joyce ChenJian SunZhiliang HuangHarry Hou JrMyra ArcillaNikolai RakhilinDaniel J JoeJiahn ChoiPoornima GadamsettyJeff MilsomGovind NandakumarRandy LongmanXi Kathy Zhou, et al.

Nature Biotechnology (2015);  33:656–660    http://dx.doi.org:/10.1038/nbt.3239

Current orthotopic xenograft models of human colorectal cancer (CRC) require surgery and do not robustly form metastases in the liver, the most common site clinically. CCR9 traffics lymphocytes to intestine and colorectum. We engineered use of the chemokine receptor CCR9 in CRC cell lines and patient-derived cells to create primary gastrointestinal (GI) tumors in immunodeficient mice by tail-vein injection rather than surgery. The tumors metastasize inducibly and robustly to the liver. Metastases have higher DKK4 and NOTCH signaling levels and are more chemoresistant than paired subcutaneous xenografts. Using this approach, we generated 17 chemokine-targeted mouse models (CTMMs) that recapitulate the majority of common human somatic CRC mutations. We also show that primary tumors can be modeled in immunocompetent mice by microinjecting CCR9-expressing cancer cell lines into early-stage mouse blastocysts, which induces central immune tolerance. We expect that CTMMs will facilitate investigation of the biology of CRC metastasis and drug screening.

Induction of the intestinal stem cell signature gene SMOC-2 is required for L1-mediated colon cancer progression

A Shvab, G Haase, A Ben-Shmuel, N Gavert, T Brabletz, S Dedhar and A Ben-Ze’ev

Oncogene , (27 April 2015) |       http://dx.doi.org:/10.1038/onc.2015.127

Overactivation of Wnt-β-catenin signaling, including β-catenin-TCF target gene expression, is a hallmark of colorectal cancer (CRC) development. We identified the immunoglobulin family of cell-adhesion receptors member L1 as a β-catenin-TCF target gene preferentially expressed at the invasive edge of human CRC tissue. L1 can confer enhanced motility and liver metastasis when expressed in CRC cells. This ability of L1-mediated metastasis is exerted by a mechanism involving ezrin and the activation of NF-κB target genes. In this study, we identified the secreted modular calcium-binding matricellular protein-2 (SMOC-2) as a gene activated by L1-ezrin-NF-κB signaling. SMOC-2 is also known as an intestinal stem cell signature gene in mice expressing Lgr5 in cells at the bottom of intestinal crypts. The induction of SMOC-2 expression in L1-expressing CRC cells was necessary for the increase in cell motility, proliferation under stress and liver metastasis conferred by L1. SMOC-2 expression induced a more mesenchymal like phenotype in CRC cells, a decrease in E-cadherin and an increase in Snail by signaling that involves integrin-linked kinase (ILK). SMOC-2 was localized at the bottom of normal human colonic crypts and at increased levels in CRC tissue with preferential expression in invasive areas of the tumor. We found an increase in Lgr5 levels in CRC cells overexpressing L1, p65 or SMOC-2, suggesting that L1-mediated CRC progression involves the acquisition of a stem cell-like phenotype, and that SMOC-2 elevation is necessary for L1-mediated induction of more aggressive/invasive CRC properties.

Global analysis of L1-transcriptomes identified IGFBP-2 as a target of ezrin and NF-κB signaling that promotes colon cancer progression

A Ben-Shmuel, A Shvab, N Gavert, T Brabletz and A Ben-Ze’ev

Oncogene 06 Aug 2012; Oncogene  (04 July 2013); 32: 3220-3230 |  http://dx.doi.org:/10.1038/onc.2012.340

L1, a neuronal cell adhesion receptor of the immunoglobulin-like protein family is expressed in invading colorectal cancer (CRC) cells as a target gene of Wnt/β-catenin signaling. Overexpression of L1 in CRC cells enhances cell motility and proliferation, and confers liver metastasis. We recently identified ezrin and the IκB-NF-κB pathway as essential for the biological properties conferred by L1 in CRC cells. Here, we studied the underlying molecular mechanisms and found that L1 enhances ezrin phosphorylation, via Rho-associated protein kinase (ROCK), and is required for L1–ezrin co-localization at the juxtamembrane domain and for enhancing cell motility. Global transcriptomes from L1-expressing CRC cells were compared with transcriptomes from the same cells expressing small hairpin RNA (shRNA) to ezrin. Among the genes whose expression was elevated by L1 and ezrin we identified insulin-like growth factor-binding protein 2 (IGFBP-2) and showed that its increased expression is mediated by an NF-κB-mediated transactivation of the IGFBP-2 gene promoter. Expression of a constitutively activated mutant ezrin (Ezrin567D) could also increase IGFBP-2 levels in CRC cells. Overexpression of IGFBP-2 in CRC cells lacking L1-enhanced cell proliferation (in the absence of serum), cell motility, tumorigenesis and induced liver metastasis, similar to L1 overexpression. Suppression of endogenous IGFBP-2 in L1-transfected cells inhibited these properties conferred by L1. We detected IGFBP-2 in a unique organization at the bottom of human colonic crypts in normal mucosa and at increased levels throughout human CRC tissue samples co-localizing with the phosphorylated p65 subunit of NF-κB. Finally, we found that IGFBP-2 and L1 can form a molecular complex suggesting that L1-mediated signaling by the L1–ezrin–NF-κB pathway, that induces IGFBP-2 expression, has an important role in CRC progression.

 

Exosome Scouts Help Tumors Populate Distant Organs

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    This image shows exosomes (green) that have infiltrated the whole lung. [Ayuko Hoshino, David Lyden, Weill Cornell Medicine

    When certain types of cancer spread, they seem to prefer particular organs in the body, a choosiness that led Stephen Paget to propose the “seed and soil” hypothesis. This hypothesis, now more than 100 years old, suggests that different organs are somehow more receptive to certain types of cancer, just as different soils seem to allow some seeds, but not others, to find purchase.

    While this hypothesis is as expressive as ever, it still lacks detail. It doesn’t suggest what mechanisms might drive organ-specific metastasis, or organotropic metastasis. The hypothesis, however, is being taken farther by researchers based at Weill Cornell Medicine. These researchers suggest that the old seed-and-soil idea, which sounds as haphazard as the dispersal of seeds by uncultivated plants, could be updated to describe a process that is more directed.

    Essentially, a tumor metastasis may proceed the way settlers cultivate new land. First, scouts and pioneers are dispatched to identify fertile spots and develop basic infrastructure. Then, once the ground is prepared, settlers establish new communities.

    In this scenario, the scouts are tumor exosomes. These exosomes are released by tumors in the millions, and they carry samples of the tumors’ proteins and genetic content. They fuse preferentially with cells at specific locations, and they ensure that recipient organs are prepared to host the tumor cells they represent.

    Most important, this updated view of organotropic metastasis includes a mechanism to explain how exosomes are directed to specific organs. The exosomes, it turns out, are outfitted with particular sets of integrins, proteins that serve as a kind of destination label.

    Supportive findings appeared October 28 in the journal Nature, in an article entitled, “Tumour exosome integrins determine organotropic metastasis.” This article described how the Weill Cornell researchers, in collaboration with scientists from the Memorial Sloan Kettering Cancer center and the Spanish National Cancer Research Centre (CNIO), examined exosomes from mouse and human lung-, liver-, and brain-tropic tumor cells. These exosomes were seen to fuse preferentially with resident cells at their predicted destinations, namely, lung fibroblasts and epithelial cells, liver Kupffer cells, and brain endothelial cells.

    “Exosome proteomics revealed distinct integrin expression patterns, in which the exosomal integrins α6β4 and α6β1 were associated with lung metastasis, while exosomal integrin αvβ5 was linked to liver metastasis,” wrote the authors. “Targeting the integrins α6β4 and αvβ5 decreased exosome uptake, as well as lung and liver metastasis, respectively.”

    In other words, the study demonstrated the importance of integrins in metastatic nesting by blocking specific integrins in tumors that metastasize to specific organs. For example, when integrins were blocked in breast cancer, metastasis to lungs was reduced. Similarly, when integrins were blocked in pancreatic cancer, metastasis to liver was reduced.

    In addition, the study showed that a tumor could be “tricked” by changing the integrin destination code of its exosomes. For example, a tumor that would normally go to the bones could be directed to the lungs instead.

    “The integrin-specific signature that we identified may have significant value clinically, serving as a prognostic indicator for metastasis to specific organ sites,” said senior author David Lyden, M.D., Ph.D., the Stavros S. Niarchos Professor in Pediatric Cardiology and a professor of pediatrics and of cell and developmental biology at Weill Cornell Medicine. “Instead of waiting for late-stage metastasis, we can now initiate preventative strategies at an earlier point of disease progression with the hope of preventing its spread. This really changes the treatment paradigm.”

     

  • Using CRISPR as a High-Throughput Cancer Screening and Modeling Tool
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    Using CRISPR/Cas9, scientists created a new high-throughput screening tool for studying the development and progression of liver cancer in mice. [Ernesto del Aguila III, NHGRI]

    A contingent of researchers from the UK, Germany, and Spain have recently developed a novel CRISPR/Cas9 system that they believe can be utilized as a multiplexed screening approach to study and model cancer development in mice. In the current study, the investigators directly mutated genes within adult mouse livers to elucidate their role in cancer development and progression—simultaneously uncovering the gene combinations that coordinate to cause liver cancer.

    “We reasoned that, by targeting mutations directly to adult liver cells using CRISPR/Cas9, we could better study and understand the biology of this important cancer,” explained co-author Mathias Friedrich, Ph.D., research scientist at the Wellcome Trust Sanger Institute. “Other approaches to engineer mutations in mice, such as stem cell manipulation, are limited by the laborious process, the long time frames and large numbers of animals needed. And, our method better mimics important aspects of human cancer biology than many “classic” mouse models: as in most human cancers, the mutations occur in the adult and only affect a few cells”.

    The findings from this study were published online recently in PNAS through an article entitled “CRISPR/Cas9 somatic multiplex-mutagenesis for high-throughput functional cancer genomics in mice.”

    This new approach is rapid, scalable, and extremely efficient, allowing the researchers to examine an array of genes or large regions of the genome concurrently. Moreover, this methodology affords scientists the ability to distinguish between cancer driver mutations and passenger mutations—those that occur as side-effects of cancer development.

    The research team developed a list of up to eighteen genes with known or unknown evidence for their importance in two forms of liver cancer. They then introduced the CRISPR/Cas9 molecules, targeting various combinations of these genes into mice, which subsequently developed liver or bile duct cancer within a few months.

    “Our approach enables us to simultaneously target multiple putative genes in individual cells,” noted co-author Roland Rad, Ph.D., project leader at the Technical University of Munich and the German Cancer Research Center Heidelberg. “We can now rapidly and efficiently screen which genes are cancer-causing and which ones are not. And, we can study how genes work together to cause cancers—a crucial piece of the puzzle we must solve to understand and tackle the disease.”

    The investigators were able to confirm that a set of DNA-binding proteins called ARID (AT-rich interactive domain), influence the organization of chromosomes and are important for liver cancer development. Furthermore, mutations in a second protein, TET2, were found to be causative in bile duct cancer: although TET2 has not been found to be mutated in human biliary cancers, the proteins that it interacts with have been, showing that the CRISPR/Cas9 method can identify human cancer genes that are not mutated, but whose function is disturbed by other events.

    “The new tools of targeting genes in combination and inducing insertions or deletions in chromosomes change our ability to identify new cancer-causing genes and to understand their role in cancer,” stated senior group leader and co-author Allan Bradley, Ph.D., director emeritus from the Sanger Institute. “Our results show that this approach is feasible and productive in liver cancer; we will now continue to study our new findings and try to extend the approach to other cancer types.”

    This CRISPR/Cas9 approach may also be favorable for an in-depth examination of genomic deserts —regions within the human genome that appear to be devoid of genes. Yet, recent data from the ENCODE Project suggests that deserts can be populated, if not by genes, then by DNA regulatory regions that influence the activity of genes.

    “Liver cancer has many DNA alterations in regions lacking genes: we don’t know which of these might be important for the disease,” said Dr. Rad. “However, we could show that it is now possible to delete such regions to systematically determine their role in liver cancer development.”

     

CRISPR Used to Create Mouse Models of Cancer

  • When scientists study the genetics of cancer, they often breed mice strains that carry selected cancer-associated mutations. But cultivating such strains, usually via transgenesis or gene targeting in embryonic stem cells, is often time-consuming and expensive. Could there be a better way—a faster, cheaper way—to create mice strains that carry particular genetic flaws?

    An alternative has been proposed by researchers from MIT. They have shown that the CRISPR gene editing system can introduce cancer-causing mutations into the livers of adult mice. The researchers anticipate that their method will allow for more rapid testing of any single genes or gene combinations that are suspected of being capable of initiating tumor formation in the liver.

    “The sequencing of human tumors has revealed hundreds of oncogenes and tumor suppressor genes in different combinations. The flexibility of this technology, as delivery gets better in the future, will give you a way to pretty rapidly test those combinations,” said Phillip Sharp, Ph.D., a professor at MIT’s Koch Institute for Integrative Cancer Research.

    Dr. Sharp was part of the MIT research team, which was led by Koch Institute director Tyler Jacks, Ph.D. Dr. Jacks noted that the CRISPR technique, which not only provides the ability to delete genes, but also to replace them with altered versions, “really opens up all sorts of new possibilities when you think about the kinds of genes that you would want to mutate in the future.” Both loss of function and gain of function, he explained, are possible.

    The MIT researchers presented their results August 6 in Nature, in an article entitled, “CRISPR-mediated direct mutation of cancer genes in the mouse liver.” It described how cancer models were generated using the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated proteins) system in vivo in wild-type mice.

    “We used hydrodynamic injection to deliver a CRISPR plasmid DNA expressing Cas9 and single guide RNAs (sgRNAs) to the liver that directly target the tumor suppressor genes Pten and p53 (also known as TP53 and Trp53), alone and in combination,” wrote the authors. “CRISPR-mediated Pten mutation led to elevated Akt phosphorylation and lipid accumulation in hepatocytes, phenocopying the effects of deletion of the gene using Cre–LoxP technology. Simultaneous targeting of Pten and p53 induced liver tumors that mimicked those caused by Cre–loxP-mediated deletion of Pten and p53.”

    Studies of such genetically engineered mice have yielded many important discoveries, but the process, which requires introducing mutations into embryonic stem cells, can take more than a year and costs hundreds of thousands of dollars. Using Cas enzymes targeted to cut snippets of p53 and Pten, the researchers were able to disrupt those two genes in about 3% of liver cells, enough to produce liver tumors within three months.

    With traditional techniques, genetically engineering such models is “a very long process,” commented Dr. Jacks. “And the more genes you’re working with, the longer and more complicated it becomes.

    The researchers also used CRISPR to create a mouse model with an oncogene called beta catenin, which makes cells more likely to become cancerous if additional mutations occur later on. To create this model, the researchers had to cut out the normal version of the gene and replace it with an overactive form, which was successful in about 0.5% of hepatocytes.

    In the Nature article, the authors emphasized that simplified methods of testing the oncogenic properties of candidates in vivo are critical. In particular, they cited the need to somehow evaluate the thousands of candidate cancer genes that are being discovered through next-generation sequencing efforts.

    Already looking forward to refining their method of generating cancer models, the authors suggested that it could attain greater sensitivity if CRISPR/Cas9-mediated mutagenesis could be performed on a “sensitized” background carrying constitutive or conditional mutations in a tumor suppressor gene such as p53. “More efficient delivery techniques, such as adenovirus or adeno-associated virus, more potent sgRNAs, and longer homologous recombination templates,” they wrote, “might also improve the overall efficiency of this method and expand the range of tissue that could be targeted.”

     

 

Bioinformatics beyond Genome Crunching  

Flow Cytometry, Workflow Development, and Other Information Stores Can Become Treasure Troves If You Use the Right IT Tools and Services

  • Click Image To Enlarge +
    Shown here is the FlowJo platform’s visualization of surface activation marker expression (CD38) on live lymphocyte CD8+ T cells. Colors represent all combinations of subsets positive and negative for interferon gamma (IFN?), perforin (Perf), and phosphorylated ERK (pERK).

    Advances in bioinformatics are no longer limited to just crunching through genomic and exosomic data. Bioinformatics, a discipline at the interface between biotechnology and information technology, also has lessons for flow cytometry and experimental design, as well as database searches, for both internal and external content.

    One company offering variations on traditional genome crunching is DNAnexus. With the advent of the $1,000 genome, researchers find themselves drowning in data. To analyze the terabytes of information, they must contract with an organization to provide the computing power, or they must perform the necessary server installation and maintenance work in house.

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Author: Tilda Barliya PhD

Metastasis, the spread of cancer cells from a primary tumour to seed secondary tumours in distant sites, is one of the greatest challenges in cancer treatment today. For many patients, by the time cancer is detected, metastasis  has already occurred. Over 80% of patients diagnosed  with lung cancer, for example, present with metastatic  disease. Few patients with metastatic cancer are cured by surgical intervention, and other treatment modalities are limited. Across all cancer types, only one in five patients diagnosed with metastatic cancer will survive more than 5 years. (1,2).

Metastatic Cancer 

  • Metastatic cancer is cancer that has spread from the place where it first started to another place in the body.
  • Metastatic cancer has the same name and same type of cancer cells as the original cancer.
  • The most common sites of cancer metastasis are the lungs, bones, and liver.
  • Treatment for metastatic cancer usually depends on the type of cancer and the size, location, and number of metastatic tumors.

How do cancer cells spread (3)

  • Local invasion: Cancer cells invade nearby normal tissue.
  • Intravasation: Cancer cells invade and move through the walls of nearby lymph vessels or blood vessels.
  • Circulation: Cancer cells move through the lymphatic system and the bloodstream to other parts of the body.

The ability of a cancer cell to metastasize successfully depends on its individual properties; the properties of the noncancerous cells, including immune system cells, present at the original location; and the properties of the cells it encounters in the lymphatic system or the bloodstream and at the final destination in another part of the body. Not all cancer cells, by themselves, have the ability to metastasize. In addition, the noncancerous cells at the original location may be able to block cancer cell metastasis. Furthermore, successfully reaching another location in the body does not guarantee that a metastatic tumor will form. Metastatic cancer cells can lie dormant (not grow) at a distant site for many years before they begin to grow again, if at all.

Although cancer therapies are improving, many drugs are not reaching the sites of metastases, and doubt  remains over the efficacy of those that do. Methods  that are effective for treating large, well-vascularized tumours may be inadequate when dealing with small clusters of disseminated malignant cells.

We expect that the expanding capabilities of nanotechnology, especially in targeting, detection and particle trafficking, will enable  novel approaches to treat cancers even after metastatic dissemination.

 

Lymph nodes, which are linked by lymphatic vessels, are distributed throughout the body and have an integral role in the immune response. Dissemination of cancer cells through the lymph network is thought to be an important route for metastatic spread. Tumor proximal lymph nodes are often the first site of metastases, and the presence of lymph node metastases signifies further metastatic spread and poor patient survival.

As such, lymph nodes have been targeted using cell-based nanotechnologies

Lymph nodes are small, bean-shaped organs that act as filters along the lymph fluid channels. As lymph fluid leaves the organ (such as breast, lung etc) and eventually goes back into the bloodstream, the lymph nodes try to catch and trap cancer cells before they reach other parts of the body. Having cancer cells in the lymph nodes suggests an increased risk of the cancer spreading. It is thus very important to evaluate the involvement of lymph nodes when choosing the best possible treatment for the patient.

Although current mapping methods are available such as CT and MRI scans, PET scan, Endobronchial Ultrasound, Mediastinoscopy and lymph node biopsy, sentinel lymph node (SLN) mapping and nodal treatment in lung cancer remain inadequate for routine clinical use. 

Certain characteristics are associated with preferential (but not exclusive) nanoparticle trafficking to lymph nodes following intravenous administration.

Targeting is often an indirect process, as receptors on the surface of leukocytes bind nanoparticles and transfer them to lymph nodes as part of a normal immune response. Several strategies have been used to enhance nanoparticle uptake by leukocytes in circulation. Coating iron-oxide nanoparticles with carbohydrates, such as dextran, results in the increased accumulation of these nanoparticles in lymph nodes. Conjugating peptides and antibodies, such as immunoglobulin G (IgG), to the particle surface also increases their accumulation in the lymphatic network. In general, negatively charged particles are taken up at faster rates than positively charged or uncharged particles. Conversely, ‘stealth’ polymers, such as polyethylene glycol (PEG), on the surface of nanoparticles, can inhibit uptake by leukocytes, thereby reducing accumulation in the lymph nodes.

Lymph node targeting may be achieved by other routes of administration. Tsuda and co-workers reported that non-cationic particles with a size range of 6–34nm, when introduced to the lungs (intrapulmonary administration), are trafficked rapidly (<1 hour) to local lymph nodes. Administering particles <80 nm in size subcutaneously also results in trafficking to lymph nodes. Interestingly, some studies have indicated that non-pegylated particles exhibit enhanced accumulation in the lymphatics and that pegylated particles tend to appear in the circulation several hours after administration.

Over the last twenty years, sentinel lymph node (SLN) imaging has revolutionized the treatment of several malignancies, such has melanoma and breast cancer, and has the potential to drastically improve treatment in other malignancies, including lung cancer. Several attempts at developing an easy, reliable, and effective method for SLN mapping in lung cancer have been unsuccessful due to unique difficulties inherent to the lung and to operating in the thoracic cavity.

An inexpensive method offering rapid, intraoperative identification of SLNs, with minimal risk to both patient and provider, would allow for improved staging in patients. This, in turn, would permit better selection of patients for adjuvant therapy, thus reducing morbidity in those patients for whom adjuvant treatment is inappropriate, and ensuring that those who need this added therapy actually receive it. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109504/)

Current methods for SLN identification involve the use of radioactivity-guided mapping with technetium-99m sulfur colloid and/or visual mapping using vital blue dyes. Unfortunately these methods can be inadequate for SLN mapping in non-small cell lung cancer (NSCLC) The use of vital blue dyes is limited in vivo by poor visibility, particularly in the presence of anthracotic mediastinal nodes, thereby decreasing the signal-to-background ratio (SBR) that enables nodal detection. Similarly, results with technetium-99m sulfur colloid have been mixed when used in the thoracic cavity, where hilar structures and aberrant patterns of lymphatic drainage make detection more difficult.

Although Nomori et al. have reported an 83% nodal identification rate following a preoperative injection of technetium-99 colloid, there is an associated increased risk of pneumothorax and bleeding with this method. Further, the recently completed CALGB 140203 multicenter Phase 2 trial investigating the use of intraoperative technetium-99m colloid found an identification rate of only 51% with this technique.  Clearly a technology with greater accuracy, improved SBR, and less potential risk to surgeon and patient would be welcome in the field of thoracic oncology.

Near-infrared (NIR) fluorescence imaging has the potential to meet this difficult challenge.

Near-Infrared Light

NIR light is defined as that within the wavelength range of 700 to 1000 nm. Although NIR light is invisible to the naked eye, it can be thought of as “redder” than UV and visible light.

  • Absorption, scatter, and autofluorescence are all significantly reduced at redder wavelengths. For instance, Hemoglobin, water, lipids, and other endogenous chromophores, such as melanin, have their lowest absorption within the NIR spectrum, which permits increased photon depth penetration into tissues
  • In addition, imaging can also be affected by photon scatter, which describes the reflection and/or deflection of light when it interacts with tissue. Scatter, on an absolute scale, is often ten-times higher than absorption. However, the two major types of scatter, Mie and Rayleigh, are both reduced in the NIR, making the use of NIR wavelengths especially important for the reduction of photon attenuation.
  • living tissue has extremely high “autofluorescence” in the UV and visible wavelength ranges due to endogenous fluorophores, such as NADH and the porphyrins. Therefore, UV/visible fluorescence imaging of the intestines, bladder, and gallbladder is essentially precluded. However, in the NIR spectrum, autofluorescence is extremely low, providing the black imaging background necessary for optimal detection of a NIR fluorophore within the surgical field
  • Additionally, optical imaging techniques, such as NIR fluorescence, eliminate the need for ionizing radiation. This, combined with the availability of a NIR fluorophore already FDA-approved for other indications and having extremely low toxicity (discussed below), make this a potentially safe imaging modality.

The main disadvantage is that it’s invisible to the human eye, requiring special imaging-systems to “see” the NIR fluorescence.

Currently there are three intraoperative NIR imaging systems in various stages of development:

  • The SPY system (Novadaq, Canada) – utilizes laser light excitation in order to obtain fluorescent images. The Spy system has been studied for imaging patency of vascular anastamoses following CABG and organ transplantation
  • The Photodynamic Eye(Hamamatsu, Japan) – is presently available only in Japan
  • The Fluorescence-Assisted Resection and Exploration (FLARE) system ()- developed by the authors’ laboratory utilizes NIR light-emitting diode (LED) excitation, eliminating the need for a potentially harmful laser. Additionally, the FLAREsystem has the advantage of being able to provide simultaneous color imaging, NIR fluorescence imaging, and color-NIR merged images, allowing the surgeon to simultaneously visualize invisible NIR fluorescence images within the context of surgical anatomy.

Near-Infrared Fluorescent Nanoparticle Contrast Agents

The ideal contrast agent for SLN mapping would be anionic and within 10–50 nm in size in order to facilitate rapid uptake into lymphatic vessels with optimal retention within the SLN.

Due to the lack of endogenous NIR tissue fluorescence, exogenous contrast agents must be administered for in vivo studies. The most important contrast agents that emit within the NIR spectrum are the heptamethine cyanines fluorophores, of which indocyanine green (ICG) is the most widely used, and fluorescent semiconductor nanocrystals, also known as quantum dots (QDs).

  • ICG is an extremely safe NIR fluorophore, with its only known toxicity being rare anaphylaxis. The dye was FDA approved in 1958 for systemic administration for indicator-dilution studies including measurements of cardiac output and hepatic function. Additionally, it is commonly used in ophthalmic angiography. When given intravenously, ICG is rapidly bound to plasma albumin and cleared from the blood via the biliary system. Peak absorption and emission of ICG occur at 780 nm and 830 nm respectively, within the window where in vivo tissue absorption is at its minimum. ICG has a relatively neutral charge, has a hydrodynamic diameter of only 1.2 nm, and is relatively hydrophobic. Unfortunately, this results in rapid transport out of the SLN and relatively low fluorescence yield, thereby decreasing its efficacy in mapping techniques. However, noncovalent adsorption of ICG to human serum albumin (HSA), as occurs within plasma, results in an anionic nanoparticle with a diameter of 7.3 nm and a three-fold increase in fluorescence yield markedly improving its utility in SLN mapping.
  • QDs consist of an inorganic heavy metal core and shell which emit within the NIR spectrum. This structure is then surrounded by a hydrophilic organic coating which facilitates aqeuous solubility and lymphatic distrubtion. QDs have been extensively studied and are ideal for SLN mapping as their hydrodynamic diameter can be customized to the appropriate size within a narrow distribution (15–20 nm), they can be engineered to have an anionic surface charge, and exhibit an extremely high SBRs with significant photostability. Unfortunately, safety concerns due to the presence of heavy metals within the QDs so far have precluded clinical application

Human Clinical Trials and NIR SLN mapping

Several studies have investigated the clinical use of indocyanine green without adsorption to HSA for NIR fluorescence-guided SLN mapping in breast and gastric cancer with good success (9-13).

Kitai et al. first examined this technique in 2005 in breast cancer patients, and was able to identify a SLN node in 17 of 18 patients using NIR fluorescence rather than the visible green color of ICG (9). Sevick-Muraca et al. reported similar results using significantly lower microdoses of ICG (10 – 100 μg), successfully identifying the SLN in 8 of 9 patients (11). Similar to these subcutaneous studies, 56 patients with gastric cancer underwent endoscopic ICG injection into the submucosa around the tumor 1 to 3 days preoperatively or injection directly into the subserosa intraoperatively with identification of the SLN in 54 patients (13).

Recently, Troyan et al. have completed a pilot phase I clinical trial examining the utility of NIR imaging the ICG:HSA nanoparticle fluorophore for SLN mapping/biopsy in breast cancer using the FLAREsystem. In this study, 6 patients received both 99mTc-sulfur colloid lymphoscintigraphy along with ICG:HSA at micromolar doses. SLNs were identified in all patients using both methods. In 4 of 6 patients the SLNs identified were the same, while in the remaining two, lymphoscintigraphy identified an additional node in one patient and ICG:HSA identified an additional SLN in the other. Irrespective, this study demonstrates that NIR SLN mapping with low dose ICG:HSA is a viable method for intraoperative SLN identification.

Nanotechnology and Drug Delivery in Lung cancer

We previously explored Lung cancer and nanotechnology aspects as polymer nanotechnology has been an area of significant research over the past decade as polymer nanoparticle drug delivery systems offer several advantages over traditional methods of chemotherapy delivery

see: (15) https://pharmaceuticalintelligence.com/2012/11/08/lung-cancer-nsclc-drug-administration-and-nanotechnology/                (16) https://pharmaceuticalintelligence.com/2012/12/01/diagnosing-lung-cancer-in-exhaled-breath-using-gold-nanoparticles/

As the importance of micrometastatic lymphatic spread of tumor becomes clearer, there has been much interest in the use of nanoparticles for lymphatic drug delivery. The considerable focus on developing an effective method for SLN mapping for lung cancer is indicative of the importance of nodal spread on overall survival.

Our lab is investigating the use of image-guided nanoparticles engineered for lymphatic drug delivery. We have previously described the synthesis of novel, pH-responsive methacrylate nanoparticle systems (14). Following a simple subcutaneous injection of NIR fluorophore-labeled nanoparticles 70 nm in size, we have shown that we can deliver paclitaxel loaded within the particles to regional draining lymph nodes in several organ systems of Yorkshire pigs while simultaneously confirming nodal migration using NIR fluorescent light. Future studies will need to investigate the ability of nanoparticles to treat and prevent nodal metastases in animal cancer models. Additionally, the development of tumor specific nanoparticles will potentially allow for targeting of chemotherapy to small groups of metastatic tumor cells further limiting systemic toxicities by narrowing the delivery of cytotoxic drugs.

Ref:

1. http://www.nature.com.rproxy.tau.ac.il/nrc/journal/v12/n1/pdf/nrc3180.pdf

2. http://www.nature.com/nrc/focus/metastasis/index.html

3. http://www.cancer.gov/cancertopics/factsheet/Sites-Types/metastatic

4. http://www.cancerresearchuk.org/cancer-help/about-cancer/what-is-cancer/body/the-lymphatic-system

5. http://www.macmillan.org.uk/Cancerinformation/Cancertypes/Lymphnodessecondary/Secondarycancerlymphnodes.aspx

6. Khullar O, Frangioni JV and Colson YL. Image-Guided Sentinel Lymph Node Mapping and Nanotechnology-Based Nodal Treatment in Lung Cancer using Invisible Near-Infrared Fluorescent Light. Semi Thorac Cardiovasc Surg 2009 :21 (4);  309-315. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109504/

7. Stacker SA, Achen MG, Jussila L,  Baldwin ME and Alitalo K. Metastasis: Lymphangiogenesis and cancer metastasis.  Nature Reviews Cancer 2002 2, 573-583. http://www.nature.com/nrc/journal/v2/n8/full/nrc863.html

8. Schroeder A., Heller DA., Winslow MM., Dahlman JE., Pratt GW., Langer R., Jacks T and Anderson DG.. Nature Reviews Cancer 2012; 12(1), 39-50. Treating metastatic cancer with nanotechnology. http://www.nature.com.rproxy.tau.ac.il/nrc/journal/v12/n1/pdf/nrc3180.pdf

http://www.nature.com.rproxy.tau.ac.il/nrc/journal/v12/n1/full/nrc3180.html

9. Kitai T, Inomoto T, Miwa M, et al. Fluorescence navigation with indocyanine green for detecting sentinel lymph nodes in breast cancer. Breast Cancer. 2005;12:211–215.

10. Ogasawara Y, Ikeda H, Takahashi M, et al. Evaluation of breast lymphatic pathways with indocyanine green fluorescence imaging in patients with breast cancer. World journal of surgery.2008;32:1924–1929.

11. Sevick-Muraca EM, Sharma R, Rasmussen JC, et al. Imaging of lymph flow in breast cancer patients after microdose administration of a near-infrared fluorophore: feasibility study. Radiology.2008;246:734–741.

12. Miyashiro I, Miyoshi N, Hiratsuka M, et al. Detection of sentinel node in gastric cancer surgery by indocyanine green fluorescence imaging: comparison with infrared imaging. Ann Surg Oncol.2008;15:1640–1643.

13. Tajima Y, Yamazaki K, Masuda Y, et al. Sentinel node mapping guided by indocyanine green fluorescence imaging in gastric cancer. Ann Surg. 2009;249:58–62.

14. Griset AP, Walpole J, Liu R, et al. Expansile nanoparticles: synthesis, characterization, and in vivo efficacy of an acid-responsive drug delivery system. J Am Chem Soc. 2009;131:2469–2471

15. https://pharmaceuticalintelligence.com/2012/11/08/lung-cancer-nsclc-drug-administration-and-nanotechnology/

16.  https://pharmaceuticalintelligence.com/2012/12/01/diagnosing-lung-cancer-in-exhaled-breath-using-gold-nanoparticles/

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