Tuesday, December 30, 2008

The CSC hypothesis: recalling some history

More about the CSC hypothesis: Cancer Stem Cells: Fact or Fiction? by Caroline Brandon, Connecting for Kids, December 26, 2008. Excerpts:
In the 1960s there was an unethical experiment where physicians took cancer cells from various types of malignancies and re-injected these cells back into the original cancer patient or another non-cancerous terminally ill patient. The results from this experiment suggested that those with cancer lacked immunity to the disease while “healthy” individuals carried some immunity to the cancer cells. However, another interesting observation was made throughout the experiments: that it requires millions of cancer cells to initiate the growth of a tumor. It is this observation from which two theories emerged in the decades to come regarding tumor initiation and maintenance.
I am hopeful that from studies like this [publication in Nature by Quintana et al] that challenge the current cancer stem cell dogma, new creative approaches will be used to uncover the true culprits behind cancer, be it a rare population of stem cells or a more common population yet to be defined.
For some additional relevant commentary, see this previous post: Tumorigenic cells not rare in human melanoma, December 3, 2008.

Comments: One "unethical experiment" of the kind described in the first excerpt is the Jewish Chronic Disease Hospital case. It has been summarized briefly in the section on injections of cancer cells, in notes entitled Nonconsensual Medical Experiments on Human Beings, by Ronald B Standler (notes created Dec 1996). The initial two sentences:
There were intradermal injections of live human cancer cells into 22 chronically ill, debilitated non-cancer patients in 1963 without their consent in the Jewish Chronic Disease Hospital case, to learn if foreign cancer cells would live longer in debilitated non-cancer patients than in patients debilitated by cancer. Lump at injection site disappeared approximately seven weeks after injection.
For a much more detailed discussion of this case from legal and ethical perspectives, see: Experimentation with Human Beings by Jay Katz, Yale University, Russell Sage Foundation, 1972 [PDF, 58 pages]. Chapter 1 is about The Jewish Chronic Disease Hospital Case. The first sentence of this chapter:
In July 1963, three doctors, with approval from the director of medicine of the Jewish Chronic Disease Hospital in Brooklyn, New York, injected "live cancer cells" subcutaneously into twenty-two chronically ill and debilitated patients.
A publication, apparently based on studies of these patients, is: Rejection of cancer homotransplants by patients with debilitating non-neoplastic diseases by Arthur G Levin, D B Custodio, Emanuel E Mandel, Chester M Southam, Ann N Y Acad Sci 1964(Nov 30); 120: 410-23 [PubMed Citation]. The full text isn't publicly accessible. From the Materials and Methods: "The recipients with non-neoplastic diseases were 19 patients at the Jewish Chronic Disease Hospital ..... The homotransplants consisted of subcutaneous injections of two to five million tissue-cultured cells. Three human cell lines of neoplastic origin were used ...". It seems inconceivable in the light of current ethical standards for human experimentation that these studies could have been carried out and published, but they were. Ethical oversight of such studies was minimal then. The summary from this publication:
Nineteen patients with advanced, debilitating, non-neoplastic diseases were given two subcutaneous homotransplants of tissue-cultured human cancer cells: one of cell line HEp 2, and one of either HEp 3 or RPMI 41. These recipients rejected the homotransplants promptly, as do normal healthy controls, whereas many patients with advanced cancer have an impaired capacity to reject these cell lines.
These findings indicate that the immunological defect which is evidenced by delayed homograft rejection is not merely a consequence of debility and cachexia.
However, although the defect occurs often in patients with advanced cancer, it is not demonstrable in all cancer patients and it cannot be assumed that it is specifically associated with cancer.
The parallelism of homograft rejection, macrophage mobilization, and delayed hypersensitivity response is discussed.
The full text begins with the statement that: "Previous studies indicate that patients with advanced cancer have an immunologic defect manifested by their inability to reject homotransplants of tissue-cultured cell lines as rapidly as healthy controls ...". The first publication cited in support of this statement is: Homotransplantation of human cell lines, Chester M Southam, Alice E Moore, Cornelius P Rhoads, Science 1957(Jan 25); 125(3239): 158-60 [PDF Extract][PubMed Citation (with the authors listed in a different order)]. Excerpt from the full text:
All recipients were volunteers who were aware of the general purposes of the study and the nature of the implanted materials and who were agreeable to subsequent biopsies ...
It should be emphasized that the standards for informed consent, and the procedures used for obtaining informed consent, were very different in 1957 in comparison with those used now.

An article about these latter experiments was published in Time magazine: Cancer Volunteers (Feb. 25, 1957). The first paragraph on the first page:
On wooden benches in the well-guarded recreation hall of the Ohio Penitentiary at Columbus sat 53 convicts—killers in for life, bank robbers, embezzlers, check forgers. Some wore the white jacket and trousers of hospital attendants (duty for which they had volunteered in the prison); others, fresh from work gangs, wore blue dungarees. As a man's name was called he walked upstairs to a room equipped as an emergency surgery, sat down and proffered a bare forearm. Dr. Chester M. Southam of Manhattan's Sloan-Kettering Institute then proceeded to inject live cancer cells.
The last paragraph on the first page:
The blobs of fluid containing the cancer cells made little bumps on each man's arm. In a matter of hours or days, some of these swelled up and became tender and inflamed; the healthy body's natural defenses were at work and plain to see. In other cases the men felt no appreciable discomfort, and the swelling disappeared without any noticeable inflammatory stage; the body's defenses had worked just as effectively but less conspicuously.
What have we learned during the 5 decades that have gone by since these studies were done? A lot about the ethics of human experimentation. A lot about how to avoid rejection, by the recipients, of transplanted cells obtained from unrelated donors. Quite a lot about tumor immunology and other aspects of tumor-host interactions. But, not enough (yet) about bioassays designed to detect, enumerate and characterize human CSC.

Monday, December 29, 2008

Criteria for review of pre-applications to CIRM

Pre-Application Review Process for Basic Biology RFA, CIRM, Agenda Item # 4, ICOC Teleconference Meeting, December 23, 2008 [PDF]. Excerpts:
The ICOC, at its most recent meeting, considered a proposal from CIRM staff to introduce a pre-application review process, on a trial basis, for use in the upcoming Basic Biology I & II and Disease Team RFAs.
Proposal: Criteria for Review of Pre-Applications

Pre-application review will focus on the essential aspects of the scientific proposal, without requiring Principal Investigators (PIs) to finalize or describe detailed research plans, budgets, collaborations or personnel. This review will consider a subset of the standard GWG criteria, tailored to the level of information we will seek in the preapplication:
1. Impact and Significance. Whether and to what extent the proposed research: addresses an important problem; significantly moves the field forward, either scientifically or medically; moves the research closer to therapy; and changes the thinking or experimental or medical practice in the field.

2. Innovation. Whether and to what extent the research approach is original, breaks new ground, and brings novel ideas, technologies or strategies to bear on an important problem.

3. Feasibility. Whether and to what extent the aims of the research can be reasonably achieved in the specified timeframe of the award.

4. Responsiveness to RFA. Whether and to what extent the proposed research project or activity adequately and appropriately addresses the goals and objectives presented in the RFA.
CIRM science staff and outside scientific specialists will apply these standard criteria. As with the criteria for GWG review of full applications, science officers will prepare guidelines that describe how these criteria apply to the concept for a specific RFA. These guidelines will be published as part of the RFA, so that PIs can address them in their preapplications.
Note that these criteria will be applied to the Disease Team RFAs.

See also: Stem cell board fails to muster quorum, skips cash request, John M Simpson, Consumer Watchdog, December 24, 2008. Excerpt:
The stem cell agency's staff had to report on the criteria they'll use in the pre-review process. They did and it's outlined here.
For a relevant previous post, see: CIRM/CSCC Joint Announcement: Disease Teams Awards, Cancer Stem Cell News, October 23, 2008.

Sunday, December 28, 2008

Two reviews about CSCs

1) An update on the biology of cancer stem cells in breast cancer by José María García Bueno and 8 co-authors, including Carmen Ramírez-Castillejo, Clin Transl Oncol 2008(Dec); 10(12): 786-93 [PubMed Citation].

2) Cancer stem cells: How can we target them? by Ivan Ischenko and 4 co-authors, including Karl-Walter Jauch and Christiane J Bruns, Curr Med Chem 2008(Dec); 15(30): 3171-84 [PubMed Citation].

[The full text isn't publicly accessible for either of these reviews].

CSCs in a mouse glioma model

Cancer stem cells are enriched in the side population cells in a mouse model of glioma by Molly A Harris and 8 co-authors, including Kyuson Yun, Cancer Res 2008(Dec 15); 68(24): 10051-9. PubMed Abstract:
The recent identification of cancer stem cells (CSCs) in multiple human cancers provides a new inroad to understanding tumorigenesis at the cellular level. CSCs are defined by their characteristics of self-renewal, multipotentiality, and tumor initiation upon transplantation. By testing for these defining characteristics, we provide evidence for the existence of CSCs in a transgenic mouse model of glioma, S100beta-verbB;Trp53. In this glioma model, CSCs are enriched in the side population (SP) cells. These SP cells have enhanced tumor-initiating capacity, self-renewal, and multipotentiality compared with non-SP cells from the same tumors. Furthermore, gene expression analysis comparing fluorescence-activated cell sorting-sorted cancer SP cells to non-SP cancer cells and normal neural SP cells identified 45 candidate genes that are differentially expressed in glioma stem cells. We validated the expression of two genes from this list (S100a4 and S100a6) in primary mouse gliomas and human glioma samples. Analyses of xenografted human glioblastoma multiforme cell lines and primary human glioma tissues show that S100A4 and S100A6 are expressed in a small subset of cancer cells and that their abundance is positively correlated to tumor grade. In conclusion, this study shows that CSCs exist in a mouse glioma model, suggesting that this model can be used to study the molecular and cellular characteristics of CSCs in vivo and to further test the CSC hypothesis.
[The full text of this article isn't publicly accessible].

Monday, December 22, 2008

Prognostic potential of CSC analysis in glioblastoma

Cancer stem cell analysis and clinical outcome in patients with glioblastoma multiforme by Roberto Pallini and 10 co-authors, including Ruggero De Maria, Clin Cancer Res 2008(Dec 15); 14(24): 8205-12. PubMed Abstract:
PURPOSE: Cancer stem cells (CSC) are thought to represent the population of tumorigenic cells responsible for tumor development. The stem cell antigen CD133 identifies such a tumorigenic population in a subset of glioblastoma patients. We conducted a prospective study to explore the prognostic potential of CSC analysis in glioblastoma patients. EXPERIMENTAL DESIGN: We investigated the relationship between the in vitro growth potential of glioblastoma CSCs and patient death or disease progression in tumors of 44 consecutive glioblastoma patients treated with complete or partial tumorectomy followed by radiotherapy combined with temozolomide treatment. Moreover, we evaluated by immunohistochemistry and immunofluorescence the prognostic value of the relative presence of CD133(+) and CD133(+)/Ki67(+) cells in patient tumors. RESULTS: In vitro CSC generation and the presence of >/=2% CD133(+) cells in tumor lesions negatively correlated with overall (P = 0.0001 and 0.02, respectively) and progression-free (P = 0.0002 and 0.01, respectively) survival of patients. A very poor overall (P = 0.007) and progression-free (P = 0.001) survival was observed among patients whose tumors contained CD133(+) cells expressing Ki67. Taking into account symptom duration, surgery type, age, O(6)-methylguanine-DNA methyltransferase promoter methylation, and p53 status, generation of CSCs and CD133/Ki67 coexpression emerged as highly significant independent prognostic factors, with an adjusted hazard ratio of 2.92 (95% confidence interval, 1.37-6.2; P = 0.005) and 4.48 (95% confidence interval, 1.68-11.9; P = 0.003), respectively. CONCLUSIONS: The analysis of CSCs may predict the survival of glioblastoma patients. In vitro CSC generation and presence of CD133(+)/Ki67(+) cells are two considerable prognostic factors of disease progression and poor clinical outcome.
See also: Prognostic relevance of SOCS3 hypermethylation in patients with glioblastoma multiforme by Maurizio Martini and 5 co-authors, including Luigi Maria Larocca, Int J Cancer 2008(Dec 15); 123(12): 2955-60 [Epub 2008(Sep 3)][PubMed Citation].

[The full text of these articles isn't publicly accessible].

Sunday, December 21, 2008

Articles about CSC in Stem Cells journal (Dec 2008)

Articles on CSC in the December 2008 (Vol 26, No 12) issue of the journal Stem Cells:

The Stem Cell-Associated Antigen CD133 (Prominin-1) Is a Molecular Therapeutic Target for Metastatic Melanoma by Germana Rappa, Oystein Fodstad, Aurelio Lorico, Stem Cells 2008; 26(12): 3008-17 [Epub 2008(Sep 18)][PubMed Citation].

Hedgehog Signaling Regulates Brain Tumor-Initiating Cell Proliferation and Portends Shorter Survival for Patients with PTEN-Coexpressing Glioblastomas by Qijin Xu and 4 co-authors, including John S Yu, Stem Cells 2008; 26(12): 3018-26 [Epub 2008(Sep 11)][PubMed Citation].

Brain Cancer Stem Cells Display Preferential Sensitivity to Akt Inhibition by Christine E Eyler and 5 co-authors, including Jeremy N Rich, Stem Cells 2008; 26(12): 3027-36 [Epub 2008(Sep 18)][PubMed Citation].

Quantitative Mass Spectrometry Identifies Drug Targets in Cancer Stem Cell-Containing Side Population by Sebastian CJ Steiniger and 4 co-authors, including Kim D Janda, Stem Cells 2008; 26(12): 3037-46 [Epub 2008(Sep 18)][PubMed Citation].

Human T-Cell Lymphotropic Virus Type 1 Infection of CD34+ Hematopoietic Progenitor Cells Induces Cell Cycle Arrest by Modulation of p21cip1/waf1 and Survivin by Prabal Banerjee and 3 co-authors, including Gerold Feuer, Stem Cells 2008; 26(12): 3047-58 [Epub 2008(Sep 25)][PubMed Citation].

Identification of a Small Subpopulation of Candidate Leukemia-Initiating Cells in the Side Population of Patients with Acute Myeloid Leukemia by Bijan Moshaver and 9 co-authors, including , Gerrit Jan Schuurhuis, Stem Cells 2008; 26(12): 3059-67 [Epub 2008(Oct 2)][PubMed Citation].

OCT4 Spliced Variants Are Differentially Expressed in Human Pluripotent and Nonpluripotent Cells by Yaser Atlasi and 4 co-authors, including Peter W Andrews, Stem Cells 2008; 26(12): 3068-74 [Epub 2008(Sep 11)][PubMed Citation].

[These articles are not publicly accessible, unlike two interviews, with Alan Trounson and Rudolf Jaenisch, in the same issue of Stem Cells].

Thursday, December 18, 2008

Two articles linking normal intestinal SC to CSC

1) Crypt stem cells as the cells-of-origin of intestinal cancer by Nick Barker and 9 co-authors, including Owen J Sansom and Hans Clevers, Nature 2008(Dec17) [Epub ahead of print]. Abstract:
Intestinal cancer is initiated by Wnt-pathway-activating mutations in genes such as adenomatous polyposis coli (APC). As in most cancers, the cell of origin has remained elusive. In a previously established Lgr5 (leucine-rich-repeat containing G-protein-coupled receptor 5) knockin mouse model, a tamoxifen-inducible Cre recombinase is expressed in long-lived intestinal stem cells[reference 1]. Here we show that deletion of Apc in these stem cells leads to their transformation within days. Transformed stem cells remain located at crypt bottoms, while fuelling a growing microadenoma. These microadenomas show unimpeded growth and develop into macroscopic adenomas within 3-5weeks. The distribution of Lgr5+ cells within stem-cell-derived adenomas indicates that a stem cell/progenitor cell hierarchy is maintained in early neoplastic lesions. When Apc is deleted in short-lived transit-amplifying cells using a different cre mouse, the growth of the induced microadenomas rapidly stalls. Even after 30weeks, large adenomas are very rare in these mice. We conclude that stem-cell-specific loss of Apc results in progressively growing neoplasia.
See also: Tracking down bowel cancer stem cells by Kat Arney, Science Update Blog, Cancer Research UK, December 17, 2008. Excerpt:
More experiments need to be done before we know for sure whether stem cells play a vital role in human bowel cancer. For now, these results are a promising step in the right direction – and a confirmation that the stem cell theory may well hold true for at least one type of cancer.

If we can understand more about the molecular pathways that control cancer, we can start to design new, more effective ways to prevent and treat the disease.
2) Prominin 1 marks intestinal stem cells that are susceptible to neoplastic transformation by Liqin Zhu and 9 co-authors, including Richard J Gilbertson, Nature 2008(Dec17) [Epub ahead of print]. Abstract:
Cancer stem cells are remarkably similar to normal stem cells: both self-renew, are multipotent and express common surface markers, for example, prominin 1 (PROM1, also called CD133)[reference 1]. What remains unclear is whether cancer stem cells are the direct progeny of mutated stem cells or more mature cells that reacquire stem cell properties during tumour formation. Answering this question will require knowledge of whether normal stem cells are susceptible to cancer-causing mutations; however, this has proved difficult to test because the identity of most adult tissue stem cells is not known. Here, using an inducible Cre, nuclear LacZ reporter allele knocked into the Prom1 locus (Prom1C-L), we show that Prom1 is expressed in a variety of developing and adult tissues. Lineage-tracing studies of adult Prom1+/C-L mice containing the Rosa26-YFP reporter allele showed that Prom1+ cells are located at the base of crypts in the small intestine, co-express Lgr5 [reference 2], generate the entire intestinal epithelium, and are therefore the small intestinal stem cell. Prom1 was reported recently to mark cancer stem cells of human intestinal tumours that arise frequently as a consequence of aberrant wingless (Wnt) signalling[references 3, 4, 5]. Activation of endogenous Wnt signalling in Prom1+/C-L mice containing a Cre-dependent mutant allele of beta-catenin (Ctnnb1lox(ex3)) resulted in a gross disruption of crypt architecture and a disproportionate expansion of Prom1 cells at the crypt base. Lineage tracing demonstrated that the progeny of these cells replaced the mucosa of the entire small intestine with neoplastic tissue that was characterized by focal high-grade intraepithelial neoplasia and crypt adenoma formation. Although all neoplastic cells arose from Prom1+ cells in these mice, only 7% of tumour cells retained Prom1 expression. Our data indicate that Prom1 marks stem cells in the adult small intestine that are susceptible to transformation into tumours retaining a fraction of mutant Prom1+ tumour cells.
See also: Molecular marker identifies normal stem cells as intestinal tumor source, News Release, St. Jude Children's Research Hospital, December 17, 2008. Excerpt:
Scientists at St. Jude Children’s Research Hospital have answered a central question in cancer biology: whether normal stem cells can give rise to tumors. Stem cells are immature cells that can renew themselves and give rise to mature differentiated cells that compose the range of body tissues. In recent years, researchers have developed evidence that cancers may arise from mutant forms of stem cells.

Tuesday, December 16, 2008

Quantifying normal human mammary epithelial SC

Human mammary glands in mice by Simone Alves, Nature Reports Stem Cells 2008(Dec 11). Excerpt:
A new technique identifies regenerative cells

Even when an organ is believed to harbour stem cells, the cells themselves can be elusive. The standard method used to hunt for mammary stem cells involves injecting cells into the mammary fat pad of mice and seeing if the cells regenerate mammary tissue. Unfortunately, this approach is time consuming, highly variable and allows no way to count the cells. In this month's Nature Medicine, Connie Eaves and her team at the British Columbia Cancer Agency, Canada, report a new technique which has allowed them, for the first time, to characterize and quantify mammary gland stem cells in humans1.
This [work] could have important implications in our understanding of breast cancer.

1. Eirew, P. et al. A method for quantifying normal human mammary epithelial stem cells with in vivo regenerative ability. Nature Med. advance online publication, doi:10.1038/nm.1791 (23 November 2008). | Article |
Another link to the same article: Peter Eirew and 6 co-authors, including Joanne T Emerman and Connie J Eaves, Nat Med 2008(Dec); 14(12): 1384-9 [Epub 2008 Nov 23]. PubMed Abstract:
Previous studies have demonstrated that normal mouse mammary tissue contains a rare subset of mammary stem cells. We now describe a method for detecting an analogous subpopulation in normal human mammary tissue. Dissociated cells are suspended with fibroblasts in collagen gels, which are then implanted under the kidney capsule of hormone-treated immunodeficient mice. After 2-8 weeks, the gels contain bilayered mammary epithelial structures, including luminal and myoepithelial cells, their in vitro clonogenic progenitors and cells that produce similar structures in secondary transplants. The regenerated clonogenic progenitors provide an objective indicator of input mammary stem cell activity and allow the frequency and phenotype of these human mammary stem cells to be determined by limiting-dilution analysis. This new assay procedure sets the stage for investigations of mechanisms regulating normal human mammary stem cells (and possibly stem cells in other tissues) and their relationship to human cancer stem cell populations.
[The commentary in Nature Reports Stem Cells is publicly accessible, but the article in Nature Medicine is not].

Sunday, December 14, 2008

A first step toward identifying prostate CSC

Making the paper: Wei-Qiang Gao, Nature 2008(Dec 11); 456(7723): xiii [Published online 10 December 2008]. Excerpt:
Search for prostate-cancer target identifies stem-cell population.

The cancer-stem-cell theory holds that tumours are formed by a very small population of self-renewing cells. The idea is controversial, but developmental biologist Wei-Qiang Gao hasn't allowed that to hamper his lab's quest to find such cells in the prostate. He and his colleagues have achieved an important first step — identifying the normal adult stem cells responsible for generating prostate tissue in mice.
[This article is not publicly accessible].

Distinguishing colorectal precancer from cancer

Reversibility of Aberrant Global DNA and Estrogen Receptor-alpha Gene Methylation Distinguishes Colorectal Precancer from Cancer by Rulong Shen and 5 co-authors, including Jian-Xin Gao, Int J Clin Exp Pathol 2009; 2(1): 21-33 [Epub 2008 Apr 20][PMC version]. PubMed Abstract:
Alterations in the global methylation of DNA and in specific regulatory genes are two epigenetic alterations found in cancer. However, the significance of epigenetic changes for diagnosis and/or prognosis of colorectal cancer have not been established, although it has been extensively investigated. Recently we have identified a new type of cancer cell called precancerous stem cells (pCSCs) and proposed that cancer may arise from a lengthy development process of tumor initiating cells (TICs) --> pCSCs --> cancer stem cells (CSCs) --> cancer, which is in parallel to histological changes of hyperplasia (TICs) --> precancer (pCSCs) --> carcinoma (CSCs/cancer cells), accompanied by clonal evolutionary epigenetic and genetic alterations. In this study, we investigated whether aberrant DNA methylation can be used as a biomarker for the differentiation between premalignant and malignant lesions in the colorectum. The profile of global DNA and estrogen receptor (ER)-alpha gene methylation during cancer development was determined by analysis of 5-methylcytosine (5-MeC) using immunohistochemical (IHC) staining, dot blot analysis or a quantitative gene methylation assay (QGMA). Herein we show that global DNA hypomethylation and ER-alpha gene hypermethylation are progressively enhanced from hyperplastic polyps (HPs) --> adenomatous polyps (APs) --> adenomatous carcinoma (AdCa). The aberrant methylation can be completely reversed in APs, but not in AdCa by a nonsteroidal anti-inflammatory drug (NSAID) celecoxib, which is a selective inhibitor of cyclooxygenase-2 (Cox-2), suggesting that the epigenetic alterations between colorectal precancer (AP) and cancer (AdCa) are fundamentally different in response to anti-cancer therapy. In normal colorectal mucosa, while global DNA methylation was not affected by aging, ER-alpha gene methylation was significantly increased with aging. However, this increase did not reach the level observed in colorectal APs. Taken together, reversibility of aberrant global DNA and ER-alpha gene methylation distinguishes colorectal precancer from cancer.
[This article is publicly accessible].

Tumor-initiating cells in murine mammary tumors

SCA-1 Identifies the Tumor-Initiating Cells in Mammary Tumors of BALB-neuT Transgenic Mice by Cristina Grange and 4 co-authors, including Benedetta Bussolati, Neoplasia 2008(Dec); 10(12): 1433-43. [PMC version]. PubMed Abstract:
Cancer stem cells, initiating and sustaining the tumor process, have been isolated in human and murine breast cancer using different cell markers. In the present study, we aimed to evaluate the presence and characteristics of stem/tumor-initiating cells in the model of the mouse mammary neoplasia driven by the activated form of rat Her-2/neu oncogene (BALB-neuT mice). For this purpose, we generated tumor spheres from primary spontaneous BALB-neuT tumors. Tumor sphere cultures were characterized for clonogenicity, self-renewal, and ability to differentiate in epithelial/myoepithelial cells of the mammary gland expressing basal and luminal cytokeratins and alpha-smooth muscle actin. In addition, tumor spheres were more resistant to doxorubicin compared with parental tumor cells. In the attempt to identify a selected marker for the sphere-generating cells, we found that Sca-1(+) cells, present in tumors or enriched in mammospheres, and not CD24(+) or CD29(+) cells, were responsible for the sphere generation in vitro. Moreover, cells from the tumor spheres showed an increased tumor-generating ability in respect to the epithelial tumor cells. Sca-1(+) sorted cells or clonal mammospheres derived from a Sca-1(+) cell showed a superimposable tumor-initiating ability. The data of the present study indicate that a Sca-1(+) population derived from mammary BALB-neuT tumors is responsible for sphere generation in culture and for initiating tumors in vivo.
[Obtain search results for Sca-1 via Pathway Commons].

Saturday, December 13, 2008

News release from CCISP

News from the Canada-California Strategic Innovation Partnership (CCSIP): The Canada-California Strategic Innovation Partnership (CCSIP) Launches First Call for Proposals with ISTPCanada and the University of California, December 10, 2008 [PDF]. Excerpt:
The CFP will be managed by International Science and Technology Partnerships Canada Inc. (ISTPCanada) and the University of California Office of the President (UCOP). It will invite innovators from academia, industry and government to propose bilateral approaches that build on Canada-California complementary strengths, address common challenges and recommend novel solutions with strong commercialization potential in areas such as: Carbon Capture and Sequestration, Green IT, Infectious Diseases, Next-Generation Digital Media and Sustainable Biofuels.

The CCSIP Steering Committee will select the winning proposals by spring 2009. The Committee aims to recommend funding for a minimum of six strategic round tables, workshops or other activities that enable the development of bilateral proposals; and six detailed business plans that could be presented to potential investors. As per previous CCSIP-stimulated initiatives, the outcomes of these projects are expected to attract investment from public and private funders. For example, the Cancer Stem Cell Consortium, a concept initially proposed at the inaugural CCSIP Summit in January 2006, garnered a $100 million commitment from Canada earlier this year.
Comment: Note that the CSCC is mentioned in the second of the paragraphs excerpted above (but not the first). Might this call for proposals (CFP) by the CCSIP include consideration of CSCC-related "bilateral approaches" that "build on Canada-California complementary strengths, address common challenges and recommend novel solutions with strong commercialization potential"? Please stay tuned.

Thursday, December 11, 2008

News release from CIRM

CIRM announces Tools and Technologies Grants to remove obstacles on the path to therapies. News Release, December 10, 2008 [PDF]. Excerpt:
Other ICOC Business

The board approved concepts for two upcoming grant programs. One was the Disease Team Awards, which are intended to accommodate the transition of basic stem cell biology into therapies. The multi-disciplinary teams are expected to initiate human clinical trials for a stem cell therapy within four years of receiving the award. This is a dramatically compressed timeline compared to the ten or more years that this process can normally take. The RFA for this award will be available in February. The board also approved the concept for the Basic Biology initiative, which is intended to drive innovation toward new therapy discoveries and to provide a strong research portfolio in basic stem cell biology. The RFA for this award is expected to be available later in December.

“These upcoming RFAs show the breadth of CIRM’s commitment to advancing basic research to the clinic,” said Trounson. “The Basic Biology Awards will ensure a steady influx of new ideas entering the therapy pipelines, while the Disease Team Awards will convert stem cell discoveries into clinical therapies. With these and the other grants we expect to distribute in the upcoming year, CIRM is positioned to drive the full spectrum of biomedical research, from developing the new ideas to breaking down barriers in stem cell research and bringing new therapies to the clinic.”

The board voted to impose no limits on the number of proposals for the Disease Team and Basic Biology initiatives. ...
[The ICOC is the Independent Citizens’ Oversight Committee of the California Institute for Regenerative Medicine (CIRM)].

Stem cell gene expression: human squamous cell carcinomas

A stem cell gene expression profile of human squamous cell carcinomas, Kim B Jensen, Judith Jones, and Fiona M Watt, Cancer Lett 2008(Dec 8); 272(1): 23–31 [PMC version]. PubMed Abstract:
To investigate the relationship between stem cells in normal epithelium and in squamous cell carcinomas (SCCs), we examined expression of a panel of human epidermal stem cell markers in SCCs and SCC cell lines. Markers that are co-expressed in normal stem cells were not co-expressed in SCC. Downregulation of two markers, Lrig1 and MAP4, and upregulation of a third, MCSP, correlated with poor differentiation status and increased proliferation in primary tumours. We conclude that SCCs do not reflect a simple expansion of stem cells; rather, tumour cells hijack the homeostatic controls that operate in normal stem cells, eliminating those that maintain stem cell quiescence.
Last paragraph of the Discussion section:
In conclusion, our data favour a model whereby during tumour development the pathways that control epithelial homeostasis are lost, particularly in the basal cell layer closest to the tumour stroma. Those markers of normal stem cells that exert a positive effect on proliferation or inhibit differentiation are upregulated, while those that normally retain the cells in a nondividing state show reduced expression. As we find out more about how different signalling pathways intersect to maintain homeostasis we will have more opportunities for restoring homeostasis in tumours.
[This is a Sponsored Article. The PMC version may be redistributed and reused, subject to certain conditions].

Tuesday, December 9, 2008

ASH 50th Anniversary Review by John Dick

Stem cell concepts renew cancer research by John E Dick, Blood 2008(Dec 15);112(13): 4793-4807. Abstract:
Although uncontrolled proliferation is a distinguishing property of a tumor as a whole, the individual cells that make up the tumor exhibit considerable variation in many properties, including morphology, proliferation kinetics, and the ability to initiate tumor growth in transplant assays. Understanding the molecular and cellular basis of this heterogeneity has important implications in the design of therapeutic strategies. The mechanistic basis of tumor heterogeneity has been uncertain; however, there is now strong evidence that cancer is a cellular hierarchy with cancer stem cells at the apex. This review provides a historical overview of the influence of hematology on the development of stem cell concepts and their linkage to cancer.
One of the most recent of the 50th Anniversary Reviews of the American Society of Hematology (ASH).

Monday, December 8, 2008

Understanding of bone marrow SC niche expanded

Detection of functional haematopoietic stem cell niche using real-time imaging by Yucai Xie, Tong Yin, Winfried Wiegraebe and 15 co-authors, including Ricardo A Feldman and Linheng Li, Nature 2008(Dec 3) [Epub ahead of print]. PubMed Abstract:
Haematopoietic stem cell (HSC) niches, although proposed decades ago, have only recently been identified as separate osteoblastic and vascular microenvironments. Their interrelationships and interactions with HSCs in vivo remain largely unknown. Here we report the use of a newly developed ex vivo real-time imaging technology and immunoassaying to trace the homing of purified green-fluorescent-protein-expressing (GFP(+)) HSCs. We found that transplanted HSCs tended to home to the endosteum (an inner bone surface) in irradiated mice, but were randomly distributed and unstable in non-irradiated mice. Moreover, GFP(+) HSCs were more frequently detected in the trabecular bone area compared with compact bone area, and this was validated by live imaging bioluminescence driven by the stem-cell-leukaemia (Scl) promoter-enhancer. HSCs home to bone marrow through the vascular system. We found that the endosteum is well vascularized and that vasculature is frequently localized near N-cadherin(+) pre-osteoblastic cells, a known niche component. By monitoring individual HSC behaviour using real-time imaging, we found that a portion of the homed HSCs underwent active division in the irradiated mice, coinciding with their expansion as measured by flow assay. Thus, in contrast to central marrow, the endosteum formed a special zone, which normally maintains HSCs but promotes their expansion in response to bone marrow damage.
Found via: Understanding Of Bone Marrow Stem Cell Niche Expanded, individualall.net Health News. Excerpt:
“EVISC technology will allow us to study HSC lineage commitment in vivo,” said Linheng Li, Ph.D., Investigator and senior author on the paper. “Furthermore, we will be able to use this technology to study leukemia (and other cancer) stem cells to better understand whether they use the same or different niches that normal stem cells use, and even to evaluate drug resistance and treatment responses. This is an exciting new avenue for our work.”

NV-128 potentially active against CSC

Novogen's NV-128 shows potential activity against cancer stem cells, Recent News, Novogen, December 1, 2008. Excerpts:
Pharmaceutical company Novogen Limited (ASX: NRT Nasdaq: NVGN) today announced that work performed in collaboration with a Yale University research team led by Associate Professor Gil Mor, MD, PhD, has revealed its novel mTOR inhibitor NV-128 has the potential to act against cancer stem cells in addition to rapidly proliferating cells in established solid tumours.

“Yale’s research team is finding that NV-128 has a high level of potency against cancer stem cells,” said Dr Gil Mor. “In fact, of the investigational therapies Yale has tried, NV-128 is one of the most exciting to us.”
Structurally, NV-128 is an analogue of triphendiol and phenoxodiol, both of which are investigational drugs that have been licensed by Novogen to Marshall Edwards, Inc.
See also: Novogen: NV-128 potentially active against cancer stem cells, Biotech Daily, December 2, 2008.

And: Marshall Edwards' Phenoxodiol and Novogen's NV-128 Display Divergent Mechanisms of Action but Potent Synergistic Anti-Cancer Activity When Used in Combination, Marketwire, October 30, 2008.

And: Anti-tumor activity of phenoxodiol: from bench to clinic by Ayesha B Alvero and 6 co-authors, including Gil Mor, Future Oncol 2008(Aug); 4(4): 475-82. [PubMed Citation].

Saturday, December 6, 2008

Published CIRM-sponsored CSC research

Found via: Stem Cell Research by CIRM Grantees:

Mutation Revealed to Convert Blood Stem Cells to Cancer Stem Cells
CIRM-funded researcher: Wei Guo

Researchers at UC, Los Angeles discovered a series of mutations that can convert normal blood stem cells into cancer stem cells. It is believed that many types of cancer result from cancer stem cells created by such mutations. In this case the first mutation converted normal stem cells and then caused over expression of an oncogene, a cancer gene, resulting in a proliferation of leukemia stem cells and acute T-cell lymphoblastic leukemia in a mouse model. The team hopes that by studying these pathways they will find ways to block them with small molecule drugs and cure the often fatal disease. The study was published in the May 22, 2008 issue of Nature.

Related Information: Nature paper, UCLA press release, The Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Funding grant summary
The published paper is: Multi-genetic events collaboratively contribute to Pten-null leukaemia stem-cell formation by Wei Guo and 10 co-authors, including Hong Wu, Nature 2008(May 22); 453(7194): 529-33 Epub 2008 May 7. [PubMed Citation].

Thursday, December 4, 2008

Guidelines for the Clinical Translation of SC

Guidelines for the Clinical Translation of Stem Cells, International Society for Stem Cell Research (ISSCR), December 3, 2008. Links are provided to the Guidelines [PDF], to Apppendix 1 (a Patient Handbook on Stem Cell Therapies) [PDF], to Appendix 2 (Additional Resources), to a Cell Stem Cell article summarizing the essential elements of the document [PubMed Citation] and to a joint ISSCR and Cell Stem Cell Press Release about the Guidelines.

For an article, in the same issue of Cell Stem Cell, that provides evidence that such Guidelines are needed, see: Stem Cell Clinics Online: The Direct-to-Consumer Portrayal of Stem Cell Medicine by Darren Lau and 5 co-authors, including Timothy Caulfield, Cell Stem Cell 2008(Dec 4); 3(6): 591-4. PubMed Abstract:
Despite the immature state of stem cell medicine, patients are seeking and accessing putative stem cell therapies in an "early market" in which direct-to-consumer advertising via the internet likely plays an important role. We analyzed stem cell clinic websites and appraised the relevant published clinical evidence of stem cell therapies to address three questions about the direct-to-consumer portrayal of stem cell medicine in this early market: What sorts of therapies are being offered? How are they portrayed? Is there clinical evidence to support the use of these therapies? We found that the portrayal of stem cell medicine on provider websites is optimistic and unsubstantiated by peer-reviewed literature.
See also: Laws needed to protect patients from stem cell clinics' exaggerated claims: study by Sheryl Ubelacker, Canadian Press, December 3, 2008. The first sentence:
Canadians should be "very skeptical" of foreign clinics that use websites to promote stem cell therapies for a wide range of medical conditions, warn researchers, saying there is a dearth of scientific evidence to back up their claims.
Comments: The Guidelines contain no explicit mention of cancer SC. However, if one accepts the prediction that "diagnostic methods based on the detection of CSC’s will have the potential to address key limitations of current methods" [excerpt from Business Wire, April 26, 2007], then some attention needs to be paid to the known limitations of diagnostic methods. Two examples of relevant references:

1) Grading quality of evidence and strength of recommendations for diagnostic tests and strategies by Holger J Schünemann and 10 co-authors, including Gordon H Guyatt, BMJ 2008(May 17); 336(7653): 1106-10 [PubMed Citation]. Excerpt from the publicly-accessible Extract:
Inferring from data on accuracy that a diagnostic test or strategy improves patient-important outcomes will require the availability of effective treatment, reduction of test related adverse effects or anxiety, or improvement of patients’ wellbeing from prognostic information.
Excerpt from the full text:
Although recommendations on diagnostic testing share the fundamental logic of recommendations on treatment, they present unique challenges.
2) See also: Evaluation of clinical innovation: a gray zone in the ethics of modern clinical practice? by Johane Patenaude and 4 co-authors, J Gen Intern Med 2008(Jan); 23(Suppl 1): 27-31 [PubMed Citation]. Excerpt for the Conclusions section of the (publicly accessible) full text:
Innovation is a neglected area for ethics assessment. Further studies on a larger scale are necessary to review the concepts of experimental, innovative, and commonly accepted care.
Perhaps a subsequent version of the ISSCR Guidelines should include a section on diagnostic tests involving CSC?

Wednesday, December 3, 2008

Tumorigenic cells not rare in human melanoma

Efficient tumour formation by single human melanoma cells by Elsa Quintana and 5 co-authors, including Sean J Morrison, Nature 2008(Dec 4); 456(7222): 593-8. Abstract:
A fundamental question in cancer biology is whether cells with tumorigenic potential are common or rare within human cancers. Studies on diverse cancers, including melanoma, have indicated that only rare human cancer cells (0.1–0.0001%) form tumours when transplanted into non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice. However, the extent to which NOD/SCID mice underestimate the frequency of tumorigenic human cancer cells has been uncertain. Here we show that modified xenotransplantation assay conditions, including the use of more highly immunocompromised NOD/SCID interleukin-2 receptor gamma chain null (Il2rg -/-) mice, can increase the detection of tumorigenic melanoma cells by several orders of magnitude. In limiting dilution assays, approximately 25% of unselected melanoma cells from 12 different patients, including cells from primary and metastatic melanomas obtained directly from patients, formed tumours under these more permissive conditions. In single-cell transplants, an average of 27% of unselected melanoma cells from four different patients formed tumours. Modifications to xenotransplantation assays can therefore dramatically increase the detectable frequency of tumorigenic cells, demonstrating that they are common in some human cancers.
See also: U-M scientists probe limits of 'cancer stem-cell model'; Melanoma, the deadliest skin cancer, does not fit the model, News Release, University of Michigan, December 3, 2008.

Article in The Scientist

How to win the war against cancer by Frank L Douglas and Robert E Litan, The Scientist, November 5, 2008 [free registration is required]. Excerpt:
We now know from many areas of science -- including cancer research -- that collaborative research by investigators with different but complementary areas of expertise are more likely to crack difficult problems than "lone rangers" who work in isolation. With more cooperation and less competition in cancer research, the war against cancer is much more likely to be won.
Over the past month, this short opinion article has attracted a number of comments from readers. An example: "Competition vs. collaboration" by an anonymous poster, November 10, 2008. Excerpt:
Therefore big bucks should be spent by the NIH on big projects, but these projects should have a purely supportive role (core facilities, tissue banks, high-throughput assay systems, result databases) and the people involved should be paid enough to make up for decreased career opportunities, which working in such supportive roles would entail. Enticing people to collaborate just because there is money in collaborating is going to just result in a lot of people flocking around the trough and pretending they have some common goal, while in fact they will be doing disparate things under a makeshift common banner.
Another example of a comment: "Doubtful strategy" by Rainer Zahlten, November 7, 2008. Excerpt:
This "new" strategy is bound to fail. Why? Because enforced cooperation for the sake of obtaining research grants is counterproductive to a physiologic matching of research interests, including a viable chemistry between participating scientists.
Thanks to Lisa Willemse, who noticed this article.

Sunday, November 30, 2008

Generation of "CSC"

Human Adult Stem Cells as the Target Cells for the Initiation of Carcinogenesis and for the Generation of "Cancer Stem Cells" by James E Trosko, International Journal of Stem Cells 2008(Nov); 1(1): 8-26 [PDF]. Abstract:
The inference to stem cells has been found in ancient myths and the concept of stem cells has existed in the fields of plant biology, developmental biology and embryology for decades. In the field of cancer research, the stem cell theory was one of the earliest hypotheses on the origin of a cancer from a single cell. However, an opposing hypothesis had it that an adult differentiated somatic cell could "de-differentiate" to become a cancer cell. Only within the last decade, via the "cloning" of Dolly, the sheep, did the field of stem cell biology really trigger an exciting revolution in biological research. The isolation of human embryonic stem cells has created a true revolution in the life sciences that has led to the hope that these human stem cells could lead to (a) basic science understanding of gene regulation during differentiation and development; (b) stem cell therapy; (c) gene therapy via stem cells; (d) the use of stem cells for drug discovery; (e) screening for toxic effects of chemicals; and (f) understand the aging and diseases of aging processes.
Comment: A wide-ranging review, in a new journal [ijstemcell.com], by one of the pioneers in studies of radiation-induced damage to the DNA of mammalian cells [example of a 1965 publication]. Some more information about this new journal is available here.

Clonal origins of relapsed ALL

Genomic analysis of the clonal origins of relapsed acute lymphoblastic leukemia by Charles G Mullighan and 6 co-authors, including James R Downing, Science 2008(Nov 28); 322(5906): 1377-80. PubMed Abstract:
Most children with acute lymphoblastic leukemia (ALL) can be cured, but the prognosis is dismal for the minority of patients who relapse after treatment. To explore the genetic basis of relapse, we performed genome-wide DNA copy number analyses on matched diagnosis and relapse samples from 61 pediatric patients with ALL. The diagnosis and relapse samples typically showed different patterns of genomic copy number abnormalities (CNAs), with the CNAs acquired at relapse preferentially affecting genes implicated in cell cycle regulation and B cell development. Most relapse samples lacked some of the CNAs present at diagnosis, which suggests that the cells responsible for relapse are ancestral to the primary leukemia cells. Backtracking studies revealed that cells corresponding to the relapse clone were often present as minor subpopulations at diagnosis. These data suggest that genomic abnormalities contributing to ALL relapse are selected for during treatment, and they point to new targets for therapeutic intervention.

Thursday, November 27, 2008

Two advance online CSHSQB articles

1) Role of "Cancer Stem Cells" and Cell Survival in Tumor Development and Maintenance by Jerry Adams and 5 co-authors, including Andreas Strasser, Cold Spring Harb Symp Quant Biol 2008(Nov 6) [Epub ahead of print]. PubMed Abstract:
One critical issue for cancer biology is the nature of the cells that drive the inexorable growth of malignant tumors. Reports that only rare cell populations within human leukemias seeded leukemia in mice stimulated the now widely embraced hypothesis that only such "cancer stem cells" maintain all tumor growth. However, the mouse microenvironment might instead fail to support the dominant human tumor cell populations. Indeed, on syngeneic transplantation of mouse lymphomas and leukemias, we and other investigators have found that a substantial proportion (>10%) of their cells drive tumor growth. Thus, dominant clones rather than rare cancer stem cells appear to sustain many tumors. Another issue is the role of cell survival in tumorigenesis. Because tumor development can be promoted by the overexpression of prosurvival genes such as bcl-2, we are exploring the role of endogenous Bcl-2-like proteins in lymphomagenesis. The absence of endogenous Bcl-2 in mice expressing an Em, u-myc transgene reduced mature B-cell numbers and enhanced their apoptosis, but unexpectedly, lymphoma development was undiminished or even delayed. This suggests that these tumors originate in an earlier cell type, such as the pro-B or pre-B cell, and that the nascent neoplastic clones do not require Bcl-2 but may instead be protected by a Bcl-2 relative.
2) Neural and Cancer Stem Cells in Tumor Suppressor Mouse Models of Malignant Astrocytoma by S Alcantara Llaguno and 3 co-authors, including Luis F Parada, Cold Spring Harb Symp Quant Biol 2008(Nov 6) [Epub ahead of print]. PubMed Abstract:
Malignant astrocytomas are highly invasive brain tumors that portend poor prognosis and dismal survival. Mouse models that genetically resemble the human malignancy provide insight into the nature and pathogenesis of these cancers. We previously reported tumor suppressor mouse models based on conditional inactivation of human astrocytoma-relevant genes p53, Nf1, and Pten. These mice develop, with full penetrance, varying grades of astrocytic malignancy that recapitulate the human condition histologically and molecularly. Our studies indicate a central role for neural stem cells and stem-cell-like cancer cells in tumor initiation and progression. These mouse models thus represent powerful tools for investigating various aspects of tumor development that otherwise cannot be explored in humans. Further studies will provide a better understanding of the biology of these tumors and will hopefully pave the way for more effective therapeutic approaches for these devastating diseases.
2008 Speaker Interviews are freely accessible, but the articles are not.

Monday, November 24, 2008

CSC and chemoradiation resistance

Cancer stem cells and chemoradiation resistance by Hideshi Ishii and 6 co-authors, including Masaki Mori, Cancer Sci 2008(Oct); 99(10): 1871-77. PubMed Abstract:
Cancer is a disease of genetic and epigenetic alterations, which are emphasized as the central mechanisms of tumor progression in the multistepwise model. Discovery of rare subpopulations of cancer stem cells (CSCs) has created a new focus in cancer research. The heterogeneity of tumors can be explained with the help of CSCs supported by antiapoptotic signaling. CSCs mimic normal adult stem cells by demonstrating resistance to toxic injuries and chemoradiation therapy. Moreover, they might be responsible for tumor relapse following apparent beneficial treatments. Compared with hematopoietic malignancies, conventional therapy regimes in solid tumors have improved the overall survival marginally, illustrating the profound impact of treatment resistance. This implies that the present therapies, which follow total elimination of rapidly dividing and differentiated tumor cells, need to be modified to target CSCs that repopulate the tumor. In this review article, we report on recent findings regarding the involvement of CSCs in chemoradiation resistance and provide new insights into their therapeutic implications in cancer.
[SHERPA/RoMEO entry for Cancer Science]

CSC research programs: Sheila K Singh

Sheila K Singh, McMaster Stem Cell and Cancer Research Institute. Excerpt:
Dr. Singh's research program is centred on the study of cancer stem cells. She recently identified an abnormal stem cell that may drive the formation of brain tumours. Using the cell surface protein CD133, Dr. Singh has characterized a rare subpopulation of brain tumour cells that exclusively generate a replica of the patient's tumour and exhibit self-renewal ability in vivo through serial retransplantation.

Her research program will focus on further molecular and genetic characterization of the brain tumour initiating cell (BTIC), and the molecular signalling pathways that are dysregulated in this cell to allow for brain tumorigenesis.
See also: Identification of human brain tumour initiating cells by Sheila K Singh and 8 co-authors, including Peter B Dirks, Nature 2004(Nov 18); 432(7015): 396-401 [PubMed Citation][Google Scholar].

Re articles published in Nature: please note the current NPG author licence policy. Excerpt:
When a manuscript is accepted for publication in an NPG journal, authors are encouraged to submit the author's version of the accepted paper (the unedited manuscript) to PubMedCentral or other appropriate funding body's archive, for public release six months after publication.

Charity event in Australia to support CSC research

Charity Auction: Sydney Harbour Cruise.
Bids close: Nov 26, 2008, 6:55 PM.
In support of cancer stem cell research. Source: Angie Cleone.

Friday, November 21, 2008

Collaboration toward purification and analysis of CSCs

Cyntellect to Collaborate with U of Florida on Cancer Stem Cells, PRNewswire, November 20, 2008. See also: Caitlyn Borst, Press Release, Cyntellect, Inc., November 20, 2008 [PDF]. Excerpt:
Cyntellect, a privately-held lifesciences company leading the development and commercialization of live cell analysis, manipulation and purification systems, announced today that it has entered a research collaboration agreement with the University of Florida Interdisciplinary Center for Biotechnology Research. The agreement will focuson a variety of research areas including the purification and analysis of cancer stem cells (CSCs), rare cells which are believed to be directly involved in propagating cancers.

Thursday, November 20, 2008

c-Myc required for maintenance of glioma CSC

c-Myc is required for maintenance of glioma cancer stem cells by Jialiang Wang and 7 co-authors, including Jeremy N Rich, PLoS ONE 2008(Nov 20); 3(11): e3769. [PMCID: PMC2582454]. Abstract:

Malignant gliomas rank among the most lethal cancers. Gliomas display a striking cellular heterogeneity with a hierarchy of differentiation states. Recent studies support the existence of cancer stem cells in gliomas that are functionally defined by their capacity for extensive self-renewal and formation of secondary tumors that phenocopy the original tumors. As the c-Myc oncoprotein has recognized roles in normal stem cell biology, we hypothesized that c-Myc may contribute to cancer stem cell biology as these cells share characteristics with normal stem cells.

Methodology/Principal Findings

Based on previous methods that we and others have employed, tumor cell populations were enriched or depleted for cancer stem cells using the stem cell marker CD133 (Prominin-1). We characterized c-Myc expression in matched tumor cell populations using real time PCR, immunoblotting, immunofluorescence and flow cytometry. Here we report that c-Myc is highly expressed in glioma cancer stem cells relative to non-stem glioma cells. To interrogate the significance of c-Myc expression in glioma cancer stem cells, we targeted its expression using lentivirally transduced short hairpin RNA (shRNA). Knockdown of c-Myc in glioma cancer stem cells reduced proliferation with concomitant cell cycle arrest in the G0/G1 phase and increased apoptosis. Non-stem glioma cells displayed limited dependence on c-Myc expression for survival and proliferation. Further, glioma cancer stem cells with decreased c-Myc levels failed to form neurospheres in vitro or tumors when xenotransplanted into the brains of immunocompromised mice.


These findings support a central role of c-Myc in regulating proliferation and survival of glioma cancer stem cells. Targeting core stem cell pathways may offer improved therapeutic approaches for advanced cancers.
The full text is openly accessible.

Monday, November 17, 2008

Liver progenitor cell population with CSC phenotype

Expansion of CD133 expressing liver cancer stem cells in liver specific PTEN deleted mice by C Bart Rountree, Wei Ding, Lina He, Bangyan Stiles, Stem Cells 2008(Nov 13). [Epub ahead of print]. PubMed Abstract:
Background: PTEN (phosphatase and tensin homologue deleted on chromosome 10) is a lipid phosphatase that regulates mitogenic signaling pathways, and deficiency of PTEN results in cell proliferation, survival, and malignancy. Murine liver specific Pten deletion models develop liver malignancy by twelve months of age. Using this model, we describe a population of CD133+ liver cancer stem cells isolated during the chronic injury phase of disease progression and before primary carcinoma formation. Methods: We performed immunohistochemistry and flow cytometry isolation using livers from 3 and 6-monthold Pten(loxp/loxp); Alb-Cre+ mice (Mutants) and controls. CD133+CD45- non-parenchymal (NP) cells were analyzed for gene expression profile and protein levels. Single CD133+CD45- oval cells were isolated for clonal expansion and tumor analysis. Cultured and freshly isolated liver CD133+CD45- and CD133-CD45- NP cells were injected into immune-deficient and immune-competent mice. Results: In Mutant mice, the NP fraction increases in CD133+CD45- cells in 3 and 6-month Pten deleted animals compared to controls. Clone lines expanded from single CD133+CD45- cells demonstrated consistent liver progenitor cell phenotype, with bi-lineage gene expression of hepatocyte and cholangiocyte markers. CD133+ cells from expanded clone lines formed robust tumors in immune-deficient and immune-competent mice. Furthermore, freshly isolated CD133+CD45- NP liver cells from six month-old Mutants formed tumors invivo, and CD133-CD45- NP cells did not. Consistent with a cancer stem cell phenotype, CD133+ cells demonstrate resistance to chemotherapy agents compared to CD133- cells. Conclusions: CD133+CD45- non-parenchymal cells from chronic injury Pten(loxp/loxp); Alb-Cre+ mice represent a bi-potent liver progenitor cell population with cancer stem cell phenotype.
The full text of this article is openly accessible [PDF].

Press release from Celprogen Inc.

Celprogen Introduces an in vivo Model for Human Brain Cancer (Human Glioblastoma GBM) for Drug Discovery Applications, Business Wire, November 17, 2008. Excerpt:
Celprogen has established a Drug Discovery program to provide drug efficacy testing services to major Pharmaceutical firms for their potential drugs against Human Glioblastoma. The other in vivo cancer model systems in the pipe line at Celprogen are: breast cancer, prostate cancer, liver cancer, colon cancer, lung cancer and pancreatic cancer that are scheduled to be released as early as the beginning of second quarter 2009. These in vivo cancer model systems are being generated from already established Celprogen’s Cancer Stem Cells.
See also: Celprogen Launches Cancer Stem Cells, Medical News Today, January 25, 2008.

About Celprogen (located in San Pedro, California).

Sunday, November 16, 2008

News release about microRNAs

UCSF team moves in on mechanism in stem cell growth, possibly cancer, News Release, UCSF News Office, November 13, 2008. Excerpt:
In recent years, microRNAs have been implicated in cancer stem cells, cancer metastases, and even in psychological and metabolic diseases.
The news release is about this publication: Embryonic stem cell–specific microRNAs regulate the G1-S transition and promote rapid proliferation by Yangming Wang and 5 co-authors, including Robert Blelloch, Nat Genet 2008(Nov 2) [Epub ahead of print]. [PubMed Citation]. The article isn't freely accessible.

Friday, November 14, 2008

Monday Nov 17 deadline for Disease Team competition

Monday deadline for Canadians on CIRM's big Disease Team round by David Jensen, The California Stem Cell Report, November 12, 2008. Excerpt:
Canadian researchers have an urgent deadline to register for the competition for a piece of possibly as much as $210 million in team-funding in an international effort involving the California stem cell agency.
See also: CIRM/CSCC Joint Announcement: Disease Teams Awards, Cancer Stem Cell News, October 23, 2008.

The link to register for the Disease Team competition is: www.cancerstemcellconsortium.com/uploads/CSCC-CIRM-DTC-EN.doc

Thursday, November 13, 2008

Chemokines in cancer and metastatic progression

The critical role of SDF-1/CXCR4 axis in cancer and cancer stem cells metastasis by Stefania Gelmini and 4 co-authors, including Elena Lazzeri, J Endocrinol Invest 2008(Sep); 31(9): 809-19 [PDF]. PubMed Abstract:
Chemokines exert their multifunctional role in several physiologic and pathologic processes through interaction with their specific receptors. Much evidence have revealed that metastatic spread tumor cells may use chemokinemediated mechanisms. In particular, an involvement of stromal cell-derived factor-1 (SDF-1) in growth of primary tumors and in metastatic process has been demonstrated. Indeed, it has been suggested that CXCR4 expression by tumor cells, plays a critical role in cell metastasis by a chemotactic gradient to organs expressing the ligand SDF-1. Moreover, CXCR4 overexpression correlated with poor prognosis in many types of cancer. In physiologic condition, SDF-1 also plays an essential role modulating stem cell proliferation, survival, and homing through its canonical receptor CXCR4. Recently, several studies have demonstrated the existence of a small subset of cancer cells which share many characteristics with stem cells and named cancer stem cells (CSC). They constitute a reservoir of self-sustaining cells with the ability to maintain the tumor growth. In particular, most of them express CXCR4 receptor and respond to a chemotactic gradient of its specific ligand SDF-1, suggesting that CSC probably represent a subpopulation capable of initiating metastasis. This review focuses on the role of SDF-1/CXCR4 axis in cancer and in the metastatic progression by tumoral cells, as well as the role of CSC in tumor pathogenesis and in metastatic process. A better understanding of migratory mechanism involving cancer cells and CSC provides a powerful tool for developing novel therapies reducing both local and distant recurrences.

Saturday, November 8, 2008

CD133 is a marker of bioenergetic stress in human glioma

CD133 is a marker of bioenergetic stress in human glioma by Corinne E Griguer and 6 co-authors, including G Yancey Gillespie, PLoS ONE 2008; 3(11): e3655. Epub 2008 Nov 5. PubMed Abstract:
Mitochondria dysfunction and hypoxic microenvironment are hallmarks of cancer cell biology. Recently, many studies have focused on isolation of brain cancer stem cells using CD133 expression. In this study, we investigated whether CD133 expression is regulated by bioenergetic stresses affecting mitochondrial functions in human glioma cells. First, we determined that hypoxia induced a reversible up-regulation of CD133 expression. Second, mitochondrial dysfunction through pharmacological inhibition of the Electron Transport Chain (ETC) produced an up-regulation of CD133 expression that was inversely correlated with changes in mitochondrial membrane potential. Third, generation of stable glioma cells depleted of mitochondrial DNA showed significant and stable increases in CD133 expression. These glioma cells, termed rho(0) or rho(0), are characterized by an exaggerated, uncoupled glycolytic phenotype and by constitutive and stable up-regulation of CD133 through many cell passages. Moreover, these rho(0) cells display the ability to form "tumor spheroids" in serumless medium and are positive for CD133 and the neural progenitor cell marker, nestin. Under differentiating conditions, rho(0) cells expressed multi-lineage properties. Reversibility of CD133 expression was demonstrated by transfering parental mitochondria to rho(0) cells resulting in stable trans-mitochondrial "cybrid" clones. This study provides a novel mechanistic insight about the regulation of CD133 by environmental conditions (hypoxia) and mitochondrial dysfunction (genetic and chemical). Considering these new findings, the concept that CD133 is a marker of brain tumor stem cells may need to be revised.
Excerpts from the Discussion section of the full text (openly accessible):
Figure 7. Tumor progression model
Last paragraph:
We described here that hypoxia and modification of the bioenergetic status of glioma cells govern the regulation of CD133 at post-transcriptional level. Data presented here strongly indicated that changes in the cellular environment that results in alteration of mitochondrial function are responsible for the enhanced up-regulation of CD133 antigen in glioma cells, suggesting that CD133 expression in human glioma cells is not obligatory relative to the stem cell phenotype but rather, reveals the occurrence of a stress response.

Friday, November 7, 2008

ErbB2 induces Notch1 activity and function in breast cancer cells

ErbB2 induces Notch1 activity and function in breast cancer cells by Jaime Lindsay and 18 co-authors, including Richard G Pestell, Clinical and Translational Science 2008(Sep 10); 2(1): 107-115. Abstract:
The ErbB2 (Her2/neu epidermal growth receptor family) oncogene is overexpressed in 30% to 40% of human breast cancers. Cyclin D1 is the regulatory subunit of the holoenzyme that phosphorylates and inactivates the retinoblastoma (pRb) tumor suppressor and is an essential downstream target of ErbB2-induced tumor growth. Herein, we demonstrate that ErbB2 induces the activity of the Notch signaling pathway. ErbB2 induction of DNA synthesis, contact-independent growth, and mammosphere induction required Notch1. ErbB2-induced cyclin D1 and cyclin D1 expression was suficient to induce Notch1 activity, and conversely, genetic deletion of Notch1 in mammary epithelial cells using foxed Notch (Notchfl/fl) mice demonstrated that cyclin D1 is induced by Notch1. Genetic deletion of cyclin D1 or small interfering RNA (siRNA) to cyclin D1-reduced Notch1 activity and reintroduction of cyclin D1 into cyclin D1-deficient cells restored Notch1 activity through the inhibition of Numb, an endogenous inhibitor of Notch1 activity. Thus, cyclin D1 functions downstream as a genetic target of Notch1, amplifies Notch1 activity by repressing Numb, and identifies a novel pathway by which ErbB2 induces Notch1 activity via the induction of cyclin D1.
At present, the full text of this article is freely accessible.

For examples of news items about this article, see: Breast Cancer - Targeting A Protein Called Cyclin D1 May Block The Expansion Of Cancerous Stem Cells, Medical News Today, November 6, 2008, and, Therapy may block expansion of breast cancer cells, Science Centric, November 6, 2008.

OncoMed press release

OncoMed Pharmaceuticals press release, November 4, 2008 [PDF]. Excerpt:
OncoMed's lead anti-cancer stem cell antibody, OMP-21M18, entered human clinical studies earlier this year with the initiation of a Phase I trial in patients with advanced solid tumors. OMP-21M18 targets a major cancer stem cell pathway, and is a part of OncoMed's collaboration with GlaxoSmithKline. The Phase I clinical trial is designed to evaluate the safety of escalating doses of OMP-21M18 in patients with solid tumors who have received previous treatment. Pharmacokinetics and initial indications of efficacy will also be assessed. OMP-21M18 is the first anti-cancer stem cell antibody against this novel target critical to cancer stem cells growth and development.
For news items about this press release, see, for example: "OncoMed Pharmaceuticals Completes Series B Financing: Lead Cancer Stem Cell Product Candidate Enters Clinical Trials", November 4, 2008 in Yahoo! Finance and The Earth Times. See also: OncoMed raises $93M in add-on funding, Lisa Sibley, Silicon Valley/San Jose Business Journal, November 4, 2008.

Tuesday, November 4, 2008

Browsing the International Cancer Research Portfolio

The Canadian Cancer Research Alliance has joined the International Cancer Research Portfolio (ICRP). Excerpt from the ICRP website: "Cancer research funders from several countries have joined in a partnership to classify their research portfolios in a common manner". The partners in the ICRP currently include major funders in the US, the UK, and Canada.

The database can be searched in various ways. For example, an Advanced Search can be carried out for the exact phrase "cancer stem cells" in the titles and abstracts of awards made in Canada, by all of the participating Canadian funding organizations, in the years 2007-2008, for all types of cancer, all areas of research and all types of projects. The results obtained for this search:
11 Total Awards
Year = 2008; 2007
This exact phrase = cancer stem cells
Country = Canada
Funding Organization = Canada
For 6 these 11 awards, the funding organization was the Canadian Institutes of Health Research (CIHR). For the remaining 5, the funding organization was the National Cancer Institute of Canada (NCIC). (Note that, at present, some organizations in Canada that provide support for cancer-related research, but within a broader mandate, are not participants in the ICRP. These include some members of the Cancer Stem Cell Consortium: The Canada Foundation for Innovation (CFI), Genome Canada and The Stem Cell Network).

An analogous search can be carried out for the exact phrase "cancer stem cells" in the titles and abstracts of awards made in California, by all of the participating US funding organizations, in the years 2007-2008, for all types of cancer, all areas of research and all types of projects. The results obtained:
25 Total Awards
Year = 2008; 2007
State = California
This exact phrase = cancer stem cells
Country = United States
Funding Organization = United States
An analogous search, for awards made by funding organizations in the US, to all states in the US, yielded a total of 89 awards. Of these, those states receiving more than 2 awards were CA (25, see above); MA (13); NY (11); TX (11); MD (6) and PA (4).

An analogous search for awards made by funding agencies in the UK, to all of the UK, yielded a total of 3 awards.

Two publications on colorectal cancer stem cells

1) Colon cancer stem cells: implications for prevention and therapy by Emina H Huang and Max S Wicha, Trends Mol Med 2008(Nov); 14(11): 503-9. Epub 2008 Oct 17. Pubmed Abstract:
The recent identification of colon cancer tumor-initiating cells adds further support to the cancer stem cell hypothesis. Ongoing basic and translational research efforts are aimed at gaining an increased understanding of the biology of these cells, as well as methods of targeting them. In addition, the relationship between colon carcinogenesis and inflammatory conditions, such as longstanding colitis and inherited syndromes, might be linked to the effect of the processes on stem cells in the colon. This review summarizes current literature on colon cancer stem cells and proposes strategies aimed at targeting these cells for colon cancer prevention and therapy.
From the "Summary" section of the full text (not publicly accessible):
The identification of colon cancer tumor-initiating cells provides further support for the cancer stem cell hypothesis. Future therapy will be directed not only at these rare cells themselves but also at the microenvironment that regulates stem cell behavior. Furthermore, because cancers might originate from disregulation of normal stem cell homeostasis, strategies for cancer prevention might also target this cell population.
2) CD44 is of functional importance for colorectal cancer stem cells by Lei Du and 10 co-authors, including Quan Chen, Clin Cancer Res 2008(Nov 1); 14(21), 6751-60. Abstract:
Purpose: Both CD44 and CD133 were reported as putative markers for isolating colorectal cancer stem cells (CSC). It remains to be resolved if both of these markers are of functional importance for colorectal CSC.
Experimental Design: The expression of CD44 and CD133 in normal colonic tissues and primary colorectal cancer was assessed by immunohistochemistry in a series of 60 patients on tissue microarray sections. Both in vitro clonogenic and in vivo tumorigenic assay were applied to measure CSC activities from the cells isolated from patients. Lentiviral RNA interference was used to stably knock down CD44 or CD133 in colorectal cancer cells from patients.
Results: We found that CD44+ cells displayed clustered growth and they did not colocalize with CD133+ cells within colorectal cancer. As few as 100 CD44+ cells from a patients' tumor initiated a xenograft tumor in vivo. A single CD44+ cell from a tumor could form a sphere in vitro which has characteristic stem cell properties and was able to generate a xenograft tumor resembling the properties of the primary tumor. Knockdown of CD44, but not CD133, strongly prevented clonal formation and inhibited tumorigenicity in xenograft model.
Conclusions: These results indicate that CD44 is a robust marker and is of functional importance for colorectal CSC for cancer initiation.
From the "Translational Relevance" section of the full text (not publicly accessible):
Cancer stem cells (CSC) represent an exciting avenue for cancer study and novel target for drug discovery. In this study, we showed that CD44 was a robust colorectal CSC marker and it is of functional importance for colorectal CSCs using clinic samples and xenograft models. The expression of CD44 and CD133 was assessed in primary tumors and matched normal tissues of patients with colorectal cancer (CRC) by using immunohistochemistry and flow cytometric analysis. We found that CD133 and CD44 did not appear on the same region of tumor tissue and it is infrequent to detect that both markers coexisted in the same cell. Knockdown of CD44 expression by RNA interference or inhibition of its function by specific antibodies could significantly inhibit tumor initiation and development in nude mice. These results indicate that CD44 and its related signaling pathway could be a critical diagnostic and therapeutic target for CRC.