On the low frequency of tumor-initiating cells

Tumor-Initiating Cells Are Rare in Many Human Tumors by Kota Ishizawa and 16 co-authors, including Benjamin G Neel and William Matsui, Cell Stem Cell 2010(Sep 3); 7(3): 279-282. [FriendFeed entry][PubMed citation]. Abstract:

Tumor-initiating cells (TICs) are defined by their ability to form tumors after xenotransplantation in immunodeficient mice and appear to be relatively rare in most human cancers. Recent data in melanoma indicate that the frequency of TICs increases dramatically via more permissive xenotransplantation conditions, raising the possibility that the true frequency of TICs has been greatly underestimated in most human tumors. We compared the growth of human pancreatic, non-small cell lung, and head and neck carcinomas in NOD/SCID and NSG mice. Although TIC frequency was detected up to 10-fold higher in NSG mice, it remained low (<1 in 2500 cells) in all cases. Moreover, aldehyde dehydrogenase-positive (ALDH(+)) and CD44(+)CD24(+) cells, phenotypically distinct cells enriched in TICs, were equally tumorigenic in NOD/SCID and NSG mice. Our findings demonstrate that TICs are rare in these cancers and that the identification of TICs and their frequency in other human malignancies should be validated via primary tumors and highly permissive xenotransplantation conditions.

Disagreement about melanoma CSCs

The Evolving Science of Cancer Stem Cells by Carmen Phillips, NCI Cancer Bulletin 2010(Jul 27); 7(15). Excerpt:

Researchers from Stanford University earlier this month reported in Nature that they had found a marker, CD271, that identified a somewhat unique population of cells that could produce melanoma in highly immunocompromised mice; anywhere from 2.5 percent to 41 percent of cells in their human tumor samples expressed the marker. In additional experiments using similar mice on which human skin was engrafted, only tumor cells with the marker could produce tumors and metastases in the mice. (In his lab, Dr. Morrison noted, the same marker did not differentiate tumor-forming from nontumor-forming cells.)

The publication about CD271 is: Human melanoma-initiating cells express neural crest nerve growth factor receptor CD271 by Alexander D Boiko and 11 colleagues, Nature 2010(Jul 1); 466(7302): 133-7. [PubMed citation].

Comments: The sentence: "In his lab, Dr. Morrison noted, the same marker did not differentiate tumor-forming from nontumor-forming cells" is noteworthy. Why the difference in results for CD271?

The publication by Boiko and co-authors was cited in a previous post to this blog, "Melanoma-initiating cells identified", dated July 1, 2010.

See also an earlier post to this blog, "Tumorigenic cells not rare in human melanoma", dated December 3, 2008.

More about salinomycin

New mission for salinomycin in cancer by Cord Naujokat, SciTopics, July 15, 2010. Excerpt (in the "continue reading" section):

In addition, a very recent study demonstrates that salinomycin overcomes ATP-binding cassette (ABC) transporter-mediated multidrug and apoptosis resistance in human leukemia stem cell-like cells (3).

Reference #3: Salinomycin overcomes ABC transporter-mediated multidrug and apoptosis resistance in human leukemia stem cell-like KG-1a cells, by Dominik Fuchs and 4 co-authors, including Cord Naujokat, Biochem Biophys Res Commun 2010(Apr 16);394(4): 1098-104 [Epub 2010(Mar 27)][PubMed citation].

Comments: Near the end of this article about salinomycin is the comment that "the investigation of its safety, toxicity, pharmacology and anticancer activity in humans will be a challenge." The author then mentions a preliminary study of "a small cohort of patients with metastatic breast cancer or metastatic head and neck cancers". The results of this preliminary study of the toxicity of salinomycin are summarized. They have not yet been published in the peer-reviewed literature, although a manuscript has been submitted [see reference #4 in the article]. The implication of these preliminary results is that there may be a "therapeutic window" for salinomycin, that is, a drug dosage that yields clinically significant benefits in the absence of excessive toxicity.

For a previous commentary on salinomycin, see: Cancer stem cell breakthrough by Kat Arney, Science Update blog, Cancer Research UK, August 14, 2009. Excerpt:

We need to stress that these were laboratory experiments, and there is no evidence yet that salinomycin can treat cancer in humans. Salinomycin is currently used as an antibiotic for chickens and cows, and it can be toxic or even fatal to humans, causing serious muscle and heart problems.

If there is a "therapeutic window" for salinomycin, it could be a small one, and is likely to vary from one tumor to another.

For a previous post to this blog about salinomycin, see: Identification of selective inhibitors of breast CSCs in mice, August 14, 2009.

CSCs responsible for metastasis identified

Cancer stem cells responsible for metastasis identified: HK study, Xinhua News Agency, June 4, 2010. Excerpt:

Hong Kong researchers have identified a subset of cancer stem cells responsible for metastasis in human colorectal cancer which can help better predict the prognosis and design a more suitable treatment for patients, according to a study made public by the University of Hong Kong on Friday.

The researchers from the university's medicine school discovered that cancer stem cells with a surface marker CD26, which marks a subset of cancer stem cells with metastatic capacity, are present in all terminal colon cancer cells and all metastatic cancer cells.

This news item is about the publication: A Subpopulation of CD26+ Cancer Stem Cells with Metastatic Capacity in Human Colorectal Cancer by Roberta Pang and 13 co-authors, including Wai Lun Law, Ronnie T Poon and Benjamin CY Wong [photos of authors], Cell Stem Cell 2010(Jun 4); 6(6): 603-15. [Summary][Twitter entry][Commentary][FriendFeed entry][Science Pond entry].

Differences that separate normal vs cancer SC molecular circuitry

Pluripotent Transcription Factors Possess Distinct Roles in Normal versus Transformed Human Stem Cells by Junfeng Ji, Tamra E Werbowetski-Ogilvie, Bonan Zhong, Seok-Ho Hong and Mickie Bhatia, PLoS ONE 2009(Nov 30); 4(11): e8065 [FriendFeed entry][Full text is publicly accessible (via Libre OA)]. PubMed Abstract:

BACKGROUND: Cancer and normal stem cells (SCs) share proliferative properties of self-renewal and expression of key transcription factors (TFs). Despite similar TF identities, the functional role of specific TFs responsible for retaining SC state has yet to be examined in cancer. METHODOLOGY/PRINCIPAL FINDINGS: Here, we compare the role of Oct4 and Nanog, two-core pluripotent TFs, in transformed (t-hPSCs), and normal human pluripotent stem cells (hPSCs). Unlike normal SCs, self-renewal and survival of t-hPSCs were found to be independent of Oct4. In contrast, t-hPSCs exhibit hypersensitivity to reduction in Nanog and demonstrate complete loss of self-renewal coupled with apoptosis. Dual and sequential knockdown of Oct4 and Nanog revealed that sensitivity of t-hPSCs to Nanog was Oct4 dependent. CONCLUSIONS/SIGNIFICANCE: Our study indicates a bifurcation for the role of two-core SC and cancer related TFs in self-renewal and survival processes. We suggest that the divergent roles of these TFs establish a paradigm to develop novel therapeutics towards selective destruction of aggressive tumors harboring cancer stem cells (CSCs) with similar molecular signatures.

MicroRNA-181 and liver cancer

Identification of microRNA-181 by genome-wide screening as a critical player in EpCAM-positive hepatic cancer stem cells by Junfang Ji and 15 co-authors, including Carlo M Croce and Xin Wei Wang, Hepatology 2009(Aug); 50(2): 472-80. [PubMed Abstract][Full text of author manuscript, available in PMC 2009(Aug 5)].

See also: EpCAM-positive hepatocellular carcinoma cells are tumor-initiating cells with stem/progenitor cell features by Taro Yamashita and 15 co-authors, including Xin Wei Wang, Gastroenterology 2009(Mar); 136(3): 1012-24.e4 [Epub 2008(Dec 5)]. [PubMed Abstract].

And: New kids on the block: Diagnostic and prognostic microRNAs in hepatocellular carcinoma by Junfang Ji and Xin Wei Wang, Cancer Biology & Therapy 2009(Sep 15); 8(18) [Forthcoming].

Human bladder tumor-initiating cells

Scientists discover bladder cancer stem cell by Krista Conger, News Release, Stanford University, August 3, 2009. First paragraph:

Researchers at Stanford's School of Medicine have identified the first human bladder cancer stem cell and revealed how it works to escape the body's natural defenses.

See also: Stanford scientists discover bladder cancer stem cell, EuekAlert, August 3, 2009. And: Scientists Discover Bladder Cancer Stem Cell, ScienceDaily, August 4, 2009. [FriendFeed entry].

The news releases are based on this Open Access publication: Identification, molecular characterization, clinical prognosis, and therapeutic targeting of human bladder tumor-initiating cells by Keith Syson Chan and 11 co-authors, including Irving L Weissman, Proc Natl Acad Sci USA 2009(Aug 4) [Epub ahead of print]. [Abstract][Early version of OA full text].

A post about another recent publication from Stanford: Leukemia SC cloak themselves to avoid detection (July 28, 2009).

CD133 and poorer prognosis in locally advanced colon cancer

Higher percentage of CD133+ cells is associated with poor prognosis in colon carcinoma patients with stage IIIB by Chun-Yan Li and 11 co-authors, including Xiao-Shi Zhang, J Transl Med 2009(Jul 7); 7: 56. [Full text via Libre OA][PMC version of the full text][PubMed Abstract] Final paragraph of the Abstract:

CONCLUSION: The fact that a higher percentage CD133+ cells were strongly associated with a poorer prognosis in patients with locally advanced colon cancer implicated that CD133+ cancer cells contribute to the tumor progression, and the overpopulation hypothesis of cancer stem cell seems reasonable.

Leukemia SC cloak themselves to avoid detection

Leukemia cells evade immune system by mimicking normal cells, Stanford study shows by Krista Conger, News Release, Stanford University Medical Center, July 23, 2009. First sentence:

Human leukemia stem cells escape detection by co-opting a protective molecular badge used by normal blood stem cells to migrate safely within the body, according to a pair of studies by researchers at Stanford University Medical School.

See also: Molecule Helps Leukemia Cells Hide From Immune System, Drugs.com, July 23, 2009. First sentence:

Leukemia stem cells cleverly cloak themselves to avoid detection by a person's immune system, according to a pair of studies by researchers at Stanford University Medical School.

And: Leukemia cells evade immune system by mimicking normal cells, Stanford studies show, EurekAlert, July 23, 2009.

The two articles upon which the news releases are based:

1) CD47 Is Upregulated on Circulating Hematopoietic Stem Cells and Leukemia Cells to Avoid Phagocytosis by Siddhartha Jaiswal, Catriona H M Jamieson and 7 co-authors, including Irving L Weissman, Cell 2009(Jul 23); 138(2): 271-85. [PubMed Citation].

2) CD47 Is an Adverse Prognostic Factor and Therapeutic Antibody Target on Human Acute Myeloid Leukemia Stem Cells by Ravindra Majeti and 7 co-authors, including Irving L Weissman, Cell 2009(Jul 23); 138(2): 286-99. [PubMed Citation][FriendFeed entry].

CD133 expression has high prognostic impact for colon cancer

The cancer stem cell marker CD133 has high prognostic impact but unknown functional relevance for the metastasis of human colon cancer by David Horst and 6 co-authors, including Thomas Kirchner and Andreas Jung, J Pathol 2009(Jun 25) [Epub ahead of print] PubMed Abstract:

In colon cancer, CD133 has recently been used to enrich for a subset of tumour cells with tumour-initiating capabilities and was therefore suggested to mark colon cancer stem cells. However, this molecule has surprisingly been shown to lack functional importance for tumour initiation itself. Herein, we investigated whether CD133 may be relevant for colon cancer metastasis in patients, and as metastasis requires several additional biological characteristics besides tumour initiation, we examined the effects of knocking down CD133 expression in colon cancer cell lines on proliferation, migration, invasion, and colony formation. We demonstrate that high CD133 expression correlates strongly with synchronous liver metastasis in a matched case-control collection, while siRNA-mediated knock down of this factor has no significant effect on the mentioned biological characteristics. Thus, we conclude that CD133 expression is a marker with high prognostic impact for colon cancer, while it seems to have no obvious functional role as a driving force of this malignancy.

Alloreactive NK cells detect and target leukemic SCs

Human acute myeloid leukemia CD34+CD38– stem cells are susceptible to allorecognition and lysis by single KIR-expressing natural killer cells by Ulrich Langenkamp and 6 co-authors, including Aleksandra Wodnar-Filipowicz, Haematologica 2009(Jul 16) [Epub ahead of print][FriendFeed entry][Early version of the full text PDF]. PubMed Abstract:

The concept of tumor immunosurveillance has raised prospects for natural killer (NK) cell-based immunotherapy of human cancer. The cure of acute myeloid leukemia (AML) may depend on eradication of leukemic stem cells (LSCs), the self-renewing component of leukemia. Whether NK cells can recognize and lyse LSCs is not known. To develop strategies that effectively target AML-LSCs, we investigated anti-leukemic effects of human alloreactive single KIR(+) NK cells. NK effectors with KIR specificity mismatched with respect to HLA class I allotype of target cells effectively recognized AML-LSCs defined phenotypically as CD34(+)CD38(-), while healthy bone marrow-derived CD34(+)CD38(-) hematopoietic stem cells were spared, as demonstrated by cytotoxicity and hematopoietic colony-forming assays. The HDAC inhibitor valproic acid augmented the activating NKG2D ligand-dependent lysis of AML-CD34(+)CD38(-) LSCs. These results show that alloreactive NK cells have the potential to detect and target LSCs, and thus to improve the treatment outcome in AML.

About AML and CML

1) First Genome-Wide Expression Analysis Yields Better Understanding of Leukemia, News Release, University of Rochester Medical Center, February 10, 2009.

Genome-wide leukemia analysis completed, UPI Science News, February 11, 2009.

These news items are about the article: Dysregulated gene expression networks in human acute myelogenous leukemia stem cells by Ravindra Majeti and 9 co-authors, including Michael W Becker, Leroy Hood, Michael F Clarke and Irving L Weissman, Proc Natl Acad Sci USA 2009(Feb 13) [Epub ahead of print][PubMed Citation][Version in PMC].

2) Scientists Uncover indicator that Warns leukemia is Progressing to more dangerous form by Steve Benowitz, News Release, UC San Diego News Center, February 17, 2009.

This news release is about the article: Glycogen synthase kinase 3{beta} missplicing contributes to leukemia stem cell generation by Annelie E Abrahamsson and 15 co-authors, including Armand Keating, Robert S Negrin, Irving L Weissman and Catriona H M Jamieson, Proc Natl Acad Sci USA 2009(Feb 23) [Epub ahead of print][PubMed Citation][Full text PDF].

Targeting tumorogenic cells in neuroblastoma cell lines

Neuroblastoma Cell Lines Contain Pluripotent Tumor Initiating Cells That Are Susceptible to a Targeted Oncolytic Virus by Yonatan Y Mahller and 8 co-authors, including Timothy P Cripe, PLoS ONE 2009; 4(1): e4235 [Epub 2009 Jan 21]. [The full text is openly accessible]. PubMed Abstract:

BACKGROUND: Although disease remission can frequently be achieved for patients with neuroblastoma, relapse is common. The cancer stem cell theory suggests that rare tumorigenic cells, resistant to conventional therapy, are responsible for relapse. If true for neuroblastoma, improved cure rates may only be achieved via identification and therapeutic targeting of the neuroblastoma tumor initiating cell. Based on cues from normal stem cells, evidence for tumor populating progenitor cells has been found in a variety of cancers. METHODOLOGY/PRINCIPAL FINDINGS: Four of eight human neuroblastoma cell lines formed tumorspheres in neural stem cell media, and all contained some cells that expressed neurogenic stem cell markers including CD133, ABCG2, and nestin. Three lines tested could be induced into multi-lineage differentiation. LA-N-5 spheres were further studied and showed a verapamil-sensitive side population, relative resistance to doxorubicin, and CD133+ cells showed increased sphere formation and tumorigenicity. Oncolytic viruses, engineered to be clinically safe by genetic mutation, are emerging as next generation anticancer therapeutics. Because oncolytic viruses circumvent typical drug-resistance mechanisms, they may represent an effective therapy for chemotherapy-resistant tumor initiating cells. A Nestin-targeted oncolytic herpes simplex virus efficiently replicated within and killed neuroblastoma tumor initiating cells preventing their ability to form tumors in athymic nude mice. CONCLUSIONS/SIGNIFICANCE: These results suggest that human neuroblastoma contains tumor initiating cells that may be effectively targeted by an oncolytic virus.

Examples of news items about this publication:

Targeting Cancer's Own Stem Cells to Fight Recurrence, Forbes, January 21, 2009. First paragraph:

Scientists have located a group of cancer stem cells or "tumor-initiating cells" which, when targeted with a reprogrammed herpes virus, are prevented from turning malignant.

Engineered Virus Targets And Kills Apparent Cancer Stem Cells In Neuroblastoma, ScienceDaily, January 21, 2009. First paragraph:

After identifying an apparent population of cancer stem cells for neuroblastoma, researchers successfully used a reprogrammed herpes virus to block tumor formation in mice by targeting and killing the cells.

Virus made to kill cancer stem cells, UPI, January 22, 2009. First paragraph:

U.S. scientists say they have engineered a virus to target and kill apparent cancer stem cells involved in neuroblastoma tumors.

SC markers invention

United States Patent Application 20090012024, Anne Collins, Norman Maitland, Steven Bryce, January 8, 2009. [See also: Stem Cell Markers and Stem cell markers]. Abstract:

We disclose gene markers of stem cells, typically prostate stem cells, and in particular cancer stem cells, for example prostate cancer stem cells; therapeutic agents and diagnostic assays based on said stem cell genes; and including screening assays to identify therapeutic agents.

Excerpt:

[0030]We have conducted gene array analysis to identify genes that are characteristic of cancer stem cells which show an up regulation when compared to control stem cell samples from normal or benign stem cell populations. We herein disclose these genes and their use in the identification of therapeutic agents useful in the treatment of cancer, in particular prostate cancer, and in the development of diagnostic assays for the detection of the early on set of tumour cell growth. The present disclosure relates to the identification of cancer stem cell specific genes.

An earlier Patent Application: 20080233640, Norman James Maitland, Anne Collins, September 25, 2008. [See also: Prostate Stem Cell and Prostate stem cell]. Abstract:

We describe a method for the isolation of prostate stem cells, typically prostate stem cells which express CD 133 antigen; stem cells and cancer stem cells isolated by the method and their use.

Two recent publications from this research group [not publicly accessible]:

Inflammation as the primary aetiological agent of human prostate cancer: a stem cell connection? Norman J Maitland, Anne T Collins, J Cell Biochem 2008(Nov 1); 105(4): 931-9 [PubMed Citation].

Prostate cancer stem cells: a new target for therapy, Norman J Maitland, Anne T Collins, J Clin Oncol 2008(Jun 10); 26(17): 2862-70 [PubMed Citation].

A recent news item:

Investors back their belief in biotech company by Bernard Ginns, Yorkshire Post, January 20, 2009. Excerpts:

Pro-Cure's expertise is in the culture, isolation, handling and gene profiling of human prostate cancer stem cells. It is working with a number of big pharmaceutical firms in this burgeoning area.

Its management team includes Professor Norman Maitland, director of Yorkshire Cancer Research and professor of molecular biology at the University of York, who is regarded as one of the world leaders in his field.

The website for Pro-Cure Therapeutics includes a page about the Management Team.

Comparing SC from the adult human brain and from brain tumors

A comparison between stem cells from the adult human brain and from brain tumors by Mercy Varghese and 8 co-authors, including Iver A Langmoen, Neurosurgery 2008(Dec); 63(6): 1022-34 [PubMed Citation].

Evaluation: Tali Siegal: Faculty of 1000 Medicine, 6 Jan 2009. Excerpt:

This study provides further evidence in support of the theory of human brain tumors deriving from apparent stem cell populations, rather than from transformation and differentiation of glial cells. The implication is that glioma stem cells should become the targets of future therapies, and, to that end, understanding the differences between normal and abnormally derived cells is important.

Characterization of human ESC with features of neoplastic progression

Characterization of human embryonic stem cells with features of neoplastic progression by Tamra E Werbowetski-Ogilvie and 15 co-authors, including Mickie Bhatia, Nat Biotechnol 2009(Jan 4) [Epub ahead of print][PubMed Citation]. Examples of news items about this research:

Scientists can now differentiate between healthy cells and cancer cells, Daily News, McMaster University, January 5, 2009.

Canadian researchers discover how to ID 'bad' from normal stem cells, CBC News, January 5, 2008.

Tests helps tease out 'good' stem cells from cancer-causing ones: study by Sheryl Ubelacker, The Canadian Press, 2009. The first two sentences:

One of the big worries about one day using stem cells to grow new organs and other tissues for curing disease is that these little regenerative powerhouses could give rise to tumours and end up doing more harm than good.

Now Canadian researchers have found a way to tell good stem cells from bad.

Autophagy and tumor dormancy in human ovarian cancer cells

The tumor suppressor gene ARHI regulates autophagy and tumor dormancy in human ovarian cancer cells by Zhen Lu and 11 co-authors, including Robert C. Bast, Jr., J Clin Invest 2008(Dec 1); 118(12): 3917-29. [PubMed Citation]. The last sentence of the Abstract:

Thus, ARHI can induce autophagic cell death, but can also promote tumor dormancy in the presence of factors that promote survival in the cancer microenvironment.

A Commentary: Autophagy-induced tumor dormancy in ovarian cancer by Ravi K Amaravadi, J Clin Invest 2008(Dec 1); 118(12): 3837-40. PubMed Abstract:

Autophagy--a process of "self-eating" that involves enzymatic digestion and recycling of cellular constituents in response to stress--contributes to both cancer cell death and survival. In this issue of the JCI, Lu et al. report that controlled induction of tumor suppressor gene aplasia Ras homolog member I (ARHI) results in autophagic cell death of human ovarian cancer cells in vitro (see the related article beginning on page 3917). However, within xenograft tumors in mice, multiple factors within the tumor microenvironment switched ARHI-induced autophagy to a mechanism of tumor cell survival, leading to tumor dormancy. Since ARHI expression is suppressed in the majority of breast and ovarian cancers but is high in premalignant lesions, ARHI-induced autophagy could be manipulated for therapeutic benefit.

[The JCI publishes all research articles immediately in PubMed Central].

See also: Dormant Cancer Cells Rely on Cellular Self-Cannibalization to Survive, News Release, The University of Texas M. D. Anderson Cancer Center, December 31, 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:

Summary

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.

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].

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].