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Health beliefs about cancer. Among the Luiseño Indians of California.

Among numerous Luiseño Indians of San Diego County, California, cancer is considered to be any tumor or growth that is possibly life threatening. A medical anthropology research project reveals that current and former Luiseño cancer patients share illness causation theories distinct from those of their kin. The patients believe their bouts with cancer stem from genetic predilection and/or God's will. In contrast, other Luiseño band members who do not have cancer assert that almost all cancer is caused by either 1.) chemical pollutants in the air, water, and food; or 2.) prior biomedical treatments that have gone awry. Imbalances of both natural and bodily elements are generally traced to particular culprits. This paper will detail these variances of Luiseño cancer etiologies and their impact on prevention policies.

Adolescent↗

Targeting of CD44 eradicates human acute myeloid leukemic stem cells.

The long-term survival of patients with acute myeloid leukemia (AML) is dismally poor. A permanent cure of AML requires elimination of leukemic stem cells (LSCs), the only cell type capable of initiating and maintaining the leukemic clonal hierarchy. We report a therapeutic approach using an activating monoclonal antibody directed to the adhesion molecule CD44. In vivo administration of this antibody to nonobese diabetic-severe combined immune-deficient mice transplanted with human AML markedly reduced leukemic repopulation. Absence of leukemia in serially transplanted mice demonstrated that AML LSCs are directly targeted. Mechanisms underlying this eradication included interference with transport to stem cell-supportive microenvironmental niches and alteration of AML-LSC fate, identifying CD44 as a key regulator of AML LSCs. The finding that AML LSCs require interaction with a niche to maintain their stem cell properties provides a therapeutic strategy to eliminate quiescent AML LSCs and may be applicable to other types of cancer stem cells.

ADP-ribosyl Cyclase 1↗

Stem cell-based treatments for gynecological solid tumors.

BACKGROUND AND OBJECTIVE: We have recently assisted to an increasing scientific interest and a new research effort in the field of stem cell-based therapy. Since the late 1980s hematopoietic stem cells (HSC) have been used to set up therapeutic strategies for the treatment of solid tumors such as gynecological cancers. In this context, different approaches have been suggested and clinically investigated. STATE OF THE ART: In the autologous setting we can describe the well-known use of HSC as hematologic support to high-dose chemotherapy regimens, and the use of HSC as a source of dendritic cells for cancer vaccination protocols. In our institution a long-term experience has been developed in high-dose chemotherapy with autologous HSC transplantation as first-line treatment of advanced ovarian cancer, and in the use of cytokines both for HSC collection and for post-transplantation hematopoietic recovery and immune reconstitution. An alternative approach consists of allogenic HSC transplantation following either myeloablative/standard or non-myeloablative/reduced conditioning regimens, which have been proposed as new adoptive immunotherapeutic treatments for different non-hematologic malignancies. PERSPECTIVES: Future strategies in the use of HSC in oncology comprise the possibility of HSC ex-vivo expansion, the use of umbilical cord blood HSC, and the development of HSC-based gene-therapy programs. Further investigations are expected in the new field of cancer stem cells.

Antineoplastic Agents↗

Validation of molecular targets in prostate cancer.

As prostate cancer is not a single disease, it is important to identify the pivotal pathway in the patient being treated. The molecular environment is the site of current oncological research to define new therapeutic targets for hormone-refractory disease, offering the potential to eventually individualize treatment through stratification of pathways. Targets may be validated either phenotypically (e.g. androgen receptor, cadherin) or functionally (e.g. prostate cancer-specific genes). In addition, several other candidates are potentially suitable, while others await discovery. Important initial steps have been made in the search for prostate cancer stem cells; identifying stem cells and the stromal, hormonal, and other signalling molecules that influence their behaviour would have important implications for managing prostate cancer. Although individual therapeutic pathways might be ineffective in a particular molecular environment, combinations of approaches might be capable of producing synergistic effects. A multimodal approach thus might be the best solution. Determining where best to search for a molecular target, and validating whether the target is associated with a sufficiently aggressive malignant process to justify further study is difficult, but the potential benefits are enormous.

Androgens↗

Hematopoietic stem cells and their niche.

Recent evidence indicates that osteoblasts are crucial components of the particular microenvironments, or niches, for hematopoietic stem cells (HSCs) in adult bone marrow (BM). Stem cells persist in an immature state within the BM. The quiescence of HSCs is controlled dynamically by the signaling of receptors-ligands and cell-adhesion molecules. In this review, the characteristics of HSCs in the niche are discussed. The understanding of the relationship between normal and cancer stem cells and their niches should lead to the development of new strategies directed toward regeneration medicine and cancer therapeutics.

Animals↗

Hypothesis: cell plasticity, linking embryonal stem cells to adult stem cell reservoirs and metastatic cancer cells?

Embryonal stem (ES) cells are the earliest ontogenetically identifiable stem cells of the embryo proper for all subsequent mesenchymal stem cells and for highly specialized differentiated cells. This review characterizes, in a working hypothesis, the role of reversible EMT/MET (epithelialmesenchymal transition) as a manifestation of cell plasticity 1) in the development of ES cells to adult stem cells (hematopoietic stem cells) and 2) in metastasizing cancer cells. Animal studies support the concept that EMT/MET is a key manifestation of cell plasticity in the development of ES cells to adult stem cells, and in conversion of localized to metastasizing cancer cells. In fact, ES cells may persist to postnatal life, in cytologically verifiable form and/or within the frame of EMT/MET, as ultimate reservoir for adult stem cells. Furthermore, EMT could possibly serve as a conceptional link between physiologic and pathologic signaling pathways. Clonal confirmation in humans is necessary.

Adult↗

Target to apoptosis: a hopeful weapon for prostate cancer.

BACKGROUND: Prostate cancer is the most commonly diagnosed neoplasm and the second leading cause of male death in this country. Multiple genetic and epigenetic factors have been implicated in the oncogenesis and progression of prostate cancer. However, the molecular mechanisms underlying the disease remain largely unknown. The major difficulty in the clinical management of prostate cancer stems from the reality that reliable and accurate diagnostic/prognostic biomarkers are not available and that effective treatment regimens for hormone-resistant prostate cancers are yet to be developed. METHODS: The present review, through extensive literature research, summarizes the most recently accumulated experimental and clinical data on the relationship between apoptosis and prostate cancer. We analyze the possibility of inducing prostate cancer cell apoptosis by: 1) androgen ablation by castration or biochemical antagonists: 2) chemotherapeutic drugs or natural/synthetic chemicals; 3) manipulation of apoptosis-related oncoproteins; and 4) modulation of intracellular signal transducers. RESULTS: 1) Prostate cancer, like most other solid tumors, represents a very heterogeneous entity. Most prostate cancers, at the time of clinical diagnosis, present themselves as mixtures of androgen-dependent and androgen-independent cells. 2) Most prostate cancers respond initially to androgen ablation since the population of androgen-dependent cells undergoes rapid apoptosis upon androgen withdrawal. However, androgen ablation rarely cures patients, most of whom will experience recurrence due to takeover of the tumor mass by androgen-independent tumor cells as well as the emergence of apoptosis-resistant clones as a result of further genetic alterations such as bcl-2 amplification. 3) On the other hand, although androgen-independent prostate cancer cells do not undergo apoptosis upon androgen blocking, they do maintain the appropriate molecular machinery of apoptosis. Therefore, certain conventional chemotherapy drugs can eliminate androgen-independent cancer cells by inducing apoptosis. 4) However, most drugs used in chemotherapy induce apoptosis or mediate cytotoxicity only in proliferating cancer cells. Human prostate cancer cells demonstrate very slow growth kinetics. Thus, novel chemical/natural products need be identified to eradicate those nonproliferating cancer cells. In this regard, the angiogenesis inhibitor, linomide, and a plant extract, beta-lapachone, demonstrate very promising apoptosis-inducing effects on prostate cancer cells in a proliferation-independent manner. 5) An alternative way to modulate the apoptotic response is by interfering with the expression levels of essential regulatory molecule of apoptosis. Bcl-2 and p53 represent two prime targets for such manipulations. 6) Finally, modulation of signal transduction pathways (e.g., intracellular Ca2+ levels, PKC activity) involved in apoptosis may also induce and/or enhance the apoptotic response of prostate cancer cells. CONCLUSIONS: Modulation of apoptotic response represents a novel mechanism-based approach which may help identify novel drugs and/or develop new therapeutic regimens for the treatment of prostate cancers.

Androgens↗

The pleiotropic effects of the SDF-1-CXCR4 axis in organogenesis, regeneration and tumorigenesis.

Proper response of normal stem cells (NSC) to motomorphogens and chemoattractants plays a pivotal role in organ development and renewal/regeneration of damaged tissues. Similar chemoattractants may also regulate metastasis of cancer stem cells (CSC). Growing experimental evidence indicates that both NSC and CSC express G-protein-coupled seven-transmembrane span receptor CXCR4 and respond to its specific ligand alpha-chemokine stromal derived factor-1 (SDF-1), which is expressed by stroma cells from different tissues. In addition, a population of very small embryonic-like (VSEL) stem cells that express CXCR4 and respond robustly to an SDF-1 gradient was recently identified in adult tissues. VSELs express several markers of embryonic and primordial germ cells. It is proposed that these cells are deposited early in the development as a dormant pool of embryonic/pluripotent NSC. Expression of both CXCR4 and SDF-1 is upregulated in response to tissue hypoxia and damage signal attracting circulating NSC and CSC. Thus, pharmacological modulation of the SDF-1-CXCR4 axis may lead to the development of new therapeutic strategies to enhance mobilization of CXCR4+ NSC and their homing to damaged organs as well as inhibition of the metastasis of CXCR4+ cancer cells.

Animals↗

Stem cell relationships and the origin of gastrointestinal cancer.

Gastrointestinal stem cells have the capacity for long-term self-replication and the ability to give rise to all other epithelial cell lineages. These properties make them essential since they maintain tissue homeostasis by regulating cell turnover depending on the current demand. However, they are also important players in the earliest stages of gastric and colonic cancer, as they form a target for mutations to accumulate and lead to the development of the malignant phenotype. Due to the lack of reliable markers, gastrointestinal stem cells are difficult to define and characterise. This limits the knowledge about their number and position within the gastric gland and the intestinal crypt, respectively, and consequently about the clonal structure of these units. Therefore, the morphological events of early gastrointestinal carcinoma formation and expansion are hotly debated. In this review we summarize the properties of gastrointestinal stem cells and illuminate their role in the development of the earliest lesions in the gastric and colonic mucosa. We also resume current opinions about the morphological pathways and the clonality of these neoplasias and the subsequent mechanism of spread within the adjacent tissues.

Cell Division↗

TGFBR3 loss and consequences in prostate cancer.

BACKGROUND: Resistance to transforming growth factor-beta (TGF-beta) is important in tumorigenesis. TGF-beta resistance mechanisms in prostate cancer are not well understood. METHODS: We have conducted a systematic analysis of TGF-beta pathway components with a meta-analysis of seven microarray studies using Oncomine and evaluated the results of TGFBR3 expression in prostate cell lines. Furthermore, we knocked down TGFBR3 in prostate epithelial cells and analyzed the consequences of TGFBR3 knockdown. RESULTS: We found that TGFBR3 is the TGF-beta component most commonly downregulated among localized human prostate cancer studies. TGFBR3 knockdown led to focus formation and enhanced expression of CD133, a marker found on prostate cancer stem cells. DNA microarray analysis of TGFBR3 knockdown cells identified 101 genes regulated by TGFBR3. Seven of these genes show a corresponding decrease in clinical prostate cancer specimens, which include genes involved in prostate mass and vasculature. CONCLUSIONS: TGFBR3 downregulation is an important step in prostate tumorigenesis.

Blotting, Western↗

Cancerous genetic peculiarities non-responsible for cancer development.

Certain genetic peculiarities recently identified in cancer cells have generally been regarded as the abnormalities responsible for cancer development. However, these abnormalities may also be found in maturable cancer cells and are not limited only to the non-maturable type. As previously described by the authors, cancer tissue consists of two types of cancerous cells: maturable and non-maturable. The development of cancer may be dependent only on the non-maturable cancerous stem cells, not on the maturable type. Since the non-maturable cell may be solely responsible for carcinogenesis, the relevant genetic peculiarities that are also found in the maturable cancer cells should not be regarded as the abnormalities responsible for carcinogenesis.

Cell Division↗

Molecular genetics in the pathology and diagnosis of retinoblastoma.

Retinoblastoma, the most common intraocular malignancy of children, has served as an important paradigm for understanding the events involved in neoplastic transformation. Much of the contemporary molecular description of human cancers stems directly from experimental approaches first developed to study this childhood tumour. This analytical methodology has demonstrated a major role for heritable predisposition in tumourigenesis, provided evidence for tissue pleiotropy of cancer genes, and revealed a more precise estimation of the number, activity, and location of other tumour suppressor loci.

Cell Transformation, Neoplastic↗

Stem-like cells in bone sarcomas: implications for tumorigenesis.

Bone sarcomas are a clinically and molecularly heterogeneous group of malignancies characterized by varying degrees of mesenchymal differentiation. Despite advances in medical and surgical management, survival rates for high-grade tumors have remained static at 50% to 70%. Tumor stem cells have been recently implicated in the pathogenesis of other heterogeneous, highly malignant tumors. We demonstrate here the existence of a small subpopulation of self-renewing bone sarcoma cells that are capable of forming suspended spherical, clonal colonies, also called "sarcospheres," in anchorage-independent, serum-starved conditions. These bone sarcoma cells as well as tissue specimens express activated STAT3 and the marker genes of pluripotent embryonic stem (ES) cells, Oct 3/4 and Nanog. Expression levels of Oct 3/4 and Nanog are greater in sarcospheres than in adherent cultures. A subset of bone sarcoma cells displays several surface markers of mesenchymal stem cells (Stro-1, CD105, and CD44) as well as attributes of mesodermal, ectodermal, and endodermal differentiation. Although previously documented in brain and breast tumors, our results support the extension of the cancer stem cell hypothesis to include tumors of mesenchymal lineage. Furthermore, they suggest the participation of ES cell homeobox proteins in non-germ cell tumorigenesis.

Bone Neoplasms↗

PTEN negatively regulates neural stem cell self-renewal by modulating G0-G1 cell cycle entry.

Previous studies have demonstrated that a small subpopulation of brain tumor cells share key characteristics with neural stem/progenitor cells in terms of phenotype and behavior. These findings suggest that brain tumors might contain "cancer stem cells" that are critical for tumor growth. However, the molecular pathways governing such stem cell-like behavior remain largely elusive. Our previous study suggests that the phosphatase and tensin homologue deleted on chromosome 10 (PTEN) tumor suppressor gene, one of the most frequently mutated genes in glioblastomas, restricts neural stem/progenitor cell proliferation in vivo. In the present study, we sought to determine the role of PTEN in long-term maintenance of stem cell-like properties, cell cycle entry and progression, and growth factor dependence and gene expression. Our results demonstrate an enhanced self-renewal capacity and G(0)-G(1) cell cycle entry and decreased growth factor dependency of Pten null neural/stem progenitor cells. Therefore, loss of PTEN leads to cell physiological changes, which collectively are sufficient to increase the pool of self-renewing neural stem cells and promote their escape from the homeostatic mechanisms of proliferation control.

Animals↗

The role of cancer vaccines following autologous stem cell rescue in breast and ovarian cancer patients: experience with the STn-KLH vaccine (Theratope).

The success of high-dose chemotherapy followed by autologous stem-cell rescue as treatment for breast and ovarian cancer is limited by a high incidence of relapse. After autologous transplantation, patients are likely to have a low tumor burden and thus would be more likely to respond immunologically to a cancer vaccine. Sialyl-Tn (STn) is a carbohydrate associated with the MUC1 mucin on breast and ovarian cancer and is an ideal candidate for vaccine immunotherapy. Sialyl-Tn-keyhole limpet hemocyanin (STn-KLH) vaccine (Theratope) incorporates a synthetic STn antigen that mimics the unique tumor-associated STn carbohydrate and is designed to stimulate tumor antigen-specific immune responses in patients with mucin-expressing tumors. Between 1995 and 2000, 70 patients (16 with stage II/III breast cancer, 17 with stage III/IV ovarian cancer, and 37 with stage IV breast cancer) were treated with 2 different formulations of STn-KLH. Toxicity, outcome, and immune response data are reported. STn-KLH was well-tolerated with minimal toxicity. The most common side effects were indurations and erythema at the sites of injections. Humoral and cellular responses were elicited in the majority of patients. Overall, these data indicate that post-autologous transplant patients are able to mount an effective immune response to vaccine immunotherapy with minimal side effects, and that vaccine immunotherapy may be a useful addition to high-dose chemotherapy regimens.

Antigens, Tumor-Associated, Carbohydrate↗

Chaperone-mediated autophagy as a regulator of hallmarks of cancer.

Chaperone-mediated autophagy (CMA) is a selective lysosomal degradation pathway that maintains cellular homeostasis by degrading soluble proteins containing KFERQ-like motifs. Although CMA has traditionally been recognized for its role in protein quality control and cellular stress adaptation, increasing evidence shows that it is frequently altered in cancer, where it regulates multiple processes that promote tumor initiation, progression, and therapy resistance. The growing number of identified CMA substrates involved in cell proliferation, apoptosis, metabolism, DNA damage response, immune regulation, inflammation, and cellular plasticity suggests that CMA is much more than a protein degradation pathway; it is an important regulator of tumor adaptation. In this review, we bring together current evidence to provide a comprehensive understanding of how CMA contributes to the Hallmarks of Cancer, including sustained proliferative signaling, resistance to cell death, metabolic reprogramming, invasion and metastasis, immune evasion, and the enabling characteristics of genome instability and tumor-promoting inflammation. We further explore the emerging roles of CMA in cellular plasticity and cancer stem cell maintenance, two interconnected processes that drive tumor progression, metastasis, and therapeutic resistance. By integrating evidence from diverse tumor types, this review provides a comprehensive understanding of how CMA shapes multiple hallmarks of cancer by selectively degrading key regulatory proteins. Finally, we highlight the context-dependent roles of CMA, identify key gaps in our current understanding, and discuss the opportunities and challenges of targeting CMA for cancer therapy. Overall, this hallmark-based perspective provides an integrated understanding of how CMA contributes to multiple hallmarks of cancer and supports its potential as a therapeutic target.

autophagy↗

Telomerase-based immunotherapy of cancer.

The progression from the cloning of human telomerase reverse transcriptase (hTERT) in 1997 to the first clinical trials of hTERT as an antitumour immunotherapy target has been swift. hTERT is overexpressed in the vast majority of human cancers yet has limited expression in normal adult tissue. It plays a critical role in oncogenesis and may be expressed by cancer stem cells. However, despite being a self antigen, hTERT is immunogenic both in vitro and in vivo. Several Phase I studies of hTERT immunotherapy have been completed in patients with breast, prostate, lung and other cancers, and clinical and immunological results are encouraging. Immunotherapy induces functional, antitumour T cells in patients in the absence of clinical toxicity. The opportunity for vaccinating individuals as an immunoprevention strategy can also be envisioned for hTERT-based therapies.

Animals↗

Wnt signalling in stem cells and cancer.

The canonical Wnt cascade has emerged as a critical regulator of stem cells. In many tissues, activation of Wnt signalling has also been associated with cancer. This has raised the possibility that the tightly regulated self-renewal mediated by Wnt signalling in stem and progenitor cells is subverted in cancer cells to allow malignant proliferation. Insights gained from understanding how the Wnt pathway is integrally involved in both stem cell and cancer cell maintenance and growth in the intestinal, epidermal and haematopoietic systems may serve as a paradigm for understanding the dual nature of self-renewal signals.

Animals↗