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.