Stem-cell transplantation for high-risk breast cancer.
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High-dose cyclophosphamide (CTX) is commonly used in preparation for autologous and allogeneic stem cell transplantation. CTX is a pro-drug, which undergoes complex oxidative metabolism with the metabolites being eliminated both renally and hepatically. In the following study, we evaluated the pharmacokinetic characteristics of high-dose CTX in three patients undergoing autologous stem cell transplantation for multiple sclerosis. The plasma concentration-time profiles for CTX and its hydroxy-metabolite were similar in multiple sclerosis patients to those reported in cancer patients undergoing stem cell transplantation. There was an increase in drug clearance after the second CTX dose indicating that the drug induced its own metabolism consistent with reports in other populations receiving high-dose CTX. One of the three patients cleared the drug slowly but this was not associated with greater toxicity. The patient with the slow clearance value and therefore highest drug exposure had stable disability scores at 2 years posttransplant compared with baseline values taken prior to transplantation. In conclusion, in this small case series, there was no indication that CTX metabolism was different than that in other populations undergoing transplantation.
We investigated the expression levels of several genes related to cell proliferation in human mesenchymal stem cells (hMSCs) during in vitro culture for use in clinical applications. In this study, we focused on the relationship between hMSC proliferation and transforming growth factor beta (TGFbeta) signaling during in vitro culture. The proliferation rate of hMSCs gradually decreased and marked changes in hMSC morphology were not observed in 3 months of in vitro culture. The mRNA expressions of TGFbeta1, TGFbeta2, and TGFbeta receptor type I (TGFbetaRI) in hMSCs increased with the length of cell culture. There had been no change in the TGFbeta3, TGFbetaRII, and TGFbetaRIII mRNA expressions by the 12th passage from the primary culture (at about 3 months). The mRNA expression of Smad3 increased, but those of c-myc and nucleostemin decreased with the length of hMSC in vitro culture. In addition, the expression profiles of the genes that regulate cellular proliferation in hMSCs were significantly different from those of cancer cells. In conclusion, hMSCs derived from bone marrow seldom underwent spontaneous transformation during 1-2 months of in vitro culture for use in clinical applications. In hMSCs as well as in epithelial cells, growth might be controlled by the TGFbeta family signaling.
INTRODUCTION: A preliminary analysis of our double high-dose chemotherapy with stem cell rescue (HD-SCR) clinical trial for breast cancer, and preclinical cross-resistant studies, suggested that melphalan (M) adversely affected response to subsequent chemotherapy, i.e., that the sequence of alkylating agents (AAs) might affect response. We, therefore, constructed and examined preclinical models to determine whether prior exposure to M, in fact, adversely affected response to other therapy. PURPOSE: The purpose of the study was to determine whether the sequence of AAs, specifically the prior use of M, adversely affected response to subsequent treatment. METHODS: The methods employed were the following: (1) Human tumor cell lines rendered resistant by in vitro sequential exposure to five different AAs were developed. The resistant cell lines were examined for cross-resistance to alkylating and other agents. (2) In vivo studies in the p388 mouse leukemia for resistance and cross-resistance among the AAs. (3) In vivo studies of the effect of sequence of AAs on response in mice bearing EMT6 breast cancer. (4) The double transplant model was developed in the mouse and the sequence of high-dose AAs was studied. (5) Biochemical and reverse transcriptase-polymerase chain reaction (RT-PCR) studies of the various resistant tumor cell lines. RESULTS: (1) The in vitro human tumor cells resistant to M were cross-resistant in 57% of tests to other AAs. In contrast, resistance for other AAs crossed to other agents in only 10 to 20% of tests. (2) The in vivo studies of p388 indicated that resistance to M commonly crossed to other AAs and many non-AAs. (3) The results for the mouse breast cancer (EMT6) studies of the sequence of AAs again indicated that M employed first markedly reduced responsiveness to subsequent treatment, particularly with AAs. (4) The double transplant model: again, M first markedly reduced response to other agents. (5) The in vitro resistant human tumor cell lines, particularly the breast cancer cell line MCF7, were found to contain high concentrations of glutathione S1 transferase gamma, which is consistent with that mechanism being responsible for resistance. CONCLUSION: The sequence of alkylating agent treatment may substantially influence response. Melphalan, particularly, produces resistance that commonly crosses to the other AAs. Mechanistic studies indicate significant changes in glutathione S1 transferase, a known mechanism for broadly based resistance to AAs.
The stem cells in the crypts of the small intestinal mucosa divide about a thousand times during the lifespan of a laboratory mouse, and yet they show little evidence of any decline in proliferative potential and rarely develop carcinogenic mutations, suggesting that their genome is extremely well protected. Protection against DNA-replication-induced errors can be achieved by the selective sorting of old (template) and new DNA strands with all template strands retained in the stem cell line. The template strands in the stem cells can be labelled during development or during tissue regeneration using tritiated thymidine ((3)HTdR). Labelling newly synthesised strands with a different marker (bromodeoxyuridine, BrdUrd) allows segregation of the two markers to be studied. Template strand label is retained ((3)HTdR), whereas label in the newly synthesised strands (BrdUrd) is lost following the second division of the stem cell. Random errors may occur in the template strands owing to environmental elements. These are protected against by the altruistic cell suicide (apoptosis) of the cells incurring such errors. A final level of protection for the tissue compensates for excessive deletion of stem cells via the apoptosis pathway. This is achieved by a hierarchical age structure in the stem cell compartment, with some cells being able to efficiently repair DNA damage and hence being more radioresistant. The presence of these protective mechanisms ensures that the small intestine rarely develops cancer and that stem cells can sustain the extensive cell proliferation needed during life.
OBJECTIVES: Prostatic intraepithelial neoplasias (PIN) result from abnormal differentiation and proliferation processes within the prostatic epithelial cell system. Recent data indicate that basal cells are essentially involved in normal and abnormal growth patterns of the human prostate. RESULTS: The basal cell layer represents the proliferative compartment and most probably houses the prostatic stem cell population. Basal cells are targets of several regulatory factors including estrogens, androgens, epidermal growth factor and other nonsteroidal growth factors. During the malignant transformation of the prostatic epithelium (PIN), the basal cell layer loses its proliferative function which is transferred to secretory luminal cell types. These proliferative abnormalities are attended by severe regulatory disorders of the programmed cell death within the prostatic epithelial cell system. The Bcl-2 oncoprotein which blocks the programmed cell death in the proliferative compartment (basal cell layer) in normal conditions, extends to the secretory luminal cell types in high-grade PIN lesions. This, in turn, may increase the genetic instability of the dysplastic epithelium. During the process of tumor invasion, the transformed cells lose their basal cell-specific phenotype and acquire features of exocrine cell types which represent the major phenotype in common prostate cancer. At the point of stromal invasion, the transformed cells produce neoplastic basement membrane material which allows them to penetrate the extracellular matrix. CONCLUSION: These data provide theoretical bases for a stem cell concept in the development of prostate cancer and highlights the importance of basal cells in this multifactorial process.
A model for carcinogenesis is presented that provides a framework for understanding the roles of "spontaneous" events, hereditary factors, and environmental agents in human carcinogenesis and for interpreting experimental carcinogenesis. This model incorporates two features: a) transition of target stem cells into cancer cells via an intermediate stage in two irreversible steps, and b) growth and differentiation of normal target and intermediate cells. Cast in mathematical terms, the model can be fitted to age-specific incidence data on human cancers of both children and adults and can illuminate the relative importance of agents that affect transition rates, tissue growth, and tissue differentiation. This is illustrated by application of the model to a) the epidemiology of lung cancer with emphasis on the role of cigarette smoking and b) the epidemiology of breast cancer with emphasis on the roles of hormones, radiation, and hereditary. The nature of the two events and of the intermediate stage is considered in light of hereditary conditions that predispose to cancer in humans. The modes of action of radiation and chemicals in carcinogenesis are discussed, as are predictions based on the model and amenable to experimental verification.
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Transcriptional profiling of patient tumors is a much-heralded advancement in cancer therapy, as it provides the opportunity to identify patients who would benefit from more or less aggressive therapy and thus allows the development of individualized treatment. However, translation of this promise into patient benefit has proven challenging. In this issue of the JCI, Glinsky and colleagues used human and murine models to identify a potential stem cell mRNA signature, based on the hypothesis that tumors with stem cell-like characteristics are likely to have a poor prognosis. Remarkably, an 11-gene "expression signature" associated with "stem cell-ness" separated patients with different cancers into good- and poor-prognosis groups. Such a "magic marker" would, if validated, have a major impact on patient care. However, there remain challenges incumbent with creating and validating such signatures.
The ribosome-inactivating protein, Shiga-like toxin-1 (SLT-1), targets cells that express the glycolipid globotriaosylceramide (CD77) on their surface. CD77 and/or SLT-1 binding was detected by flow cytometry and immunocytochemistry on lymphoma and breast cancer cells recovered from biopsies of primary human cancers as well as on B cells or plasma cells present in blood/bone marrow samples of multiple myeloma patients. Breast cancer cell lines also expressed receptors for the toxin and were sensitive to SLT-1. Treatment of primary B lymphoma, B-cell chronic lymphocytic leukemia, and myeloma B or plasma cells with SLT-1-depleted malignant B cells by 3- to 28-fold, as measured by flow cytometry. Depletion of myeloma plasma cells was confirmed using a cellular limiting dilution assay followed by reverse transcriptase-polymerase chain reaction analysis of clonotypic IgH transcripts, which showed a greater than 3 log reduction in clonotypic myeloma cells after SLT-1 treatment. Receptors for the toxin were not detected on human CD34(+) hematopoietic progenitor cells (HPC). HPC were pretreated with a concentration of SLT-1 known to purge primary malignant B cells and cultured for 6 days. The number of HPC was comparable in toxin-treated and untreated cultures. HPC were functionally intact as well. Colony-forming units (CFU) were present at an identical frequency in untreated and SLT-1 pretreated cultures, confirming that CFU escape SLT-1 toxicity. The results suggest the ex vivo use of SLT-1 in purging SLT-1 receptor-expressing malignant cells from autologous stem cell grafts of breast cancer, lymphoma, and myeloma patients.
Between April 1997 and March 1998 we evaluated the immune response and outcome in 11 chemosensitive patients who were treated with the anti-idiotype antibody vaccine TriAb after recovery from intensive therapy and autologous stem cell transplant (ASCT). Triab was commenced after recovery from the acute effects of ASCT; a minimum interval of 1 month was required from completion of consolidation radiotherapy, if given. Nine patients (82%) manifest anti-anti-idiotype antibody (Ab3) responses post ASCT. The maximal Ab3 response was seen after a median of 10 doses (range 5-20), which corresponded to a median of 14 months (range 5-19) post ASCT. Evidence of a T cell proliferative response was seen in eight patients; the response was modest in most of these. At a median follow-up of 24 months (range 22-33) after ASCT, four patients are alive without evidence of disease progression. All four of these patients were in the subgroup with more vigorous immune responses. Subsequent efforts have been directed toward the achievement of higher levels of immune responses more rapidly post ASCT. Bone Marrow Transplantation (2000) 26, 729-735.
Evidence based on immunocytochemical staining and ultrastructure suggests that morphological gradations between epithelial and myoepithelial cells, and possibly between epithelial cells and alveolar-like cells occur in terminal ductal structures of rat and human mammary glands. The benign carcinogen-induced rat and benign human mammary tumors can contain epithelial, myoepithelial-like and alveolar-like cells, whereas the malignant counterparts mainly contain only epithelial-like cells. Clonal epithelial cell lines from normal rat mammary glands, benign tumors, and SV40-transformed human mammary glands can differentiate to either myoepithelial-like or alveolar-like cells. In those of the rat, the differentiation processes occur in steps: intermediate cells along the myoepithelial-like pathway resemble intermediates in terminal ductal structures in vivo, and can also generate certain well-differentiated mesenchymal elements of the original tumours. Differentiation of the benign rat cells to alveolar-like cells with mammatrophic hormones and retinoids in vitro leads to a reduction in their tumor-forming ability in vivo. Cell lines from malignant rat mammary tumors of increasing metastatic potential and from human ductal carcinomas largely fail to yield myoepithelial-like or alveolar-like cells and are relatively slow-growing. Growth of the rat mammary epithelial cells in culture is stimulated by a pituitary-derived mammatrophic growth factor (PMGF), prostaglandin E2, and alpha-transforming growth factor; the response of the malignant cell lines to PMGF is reduced. It is suggested that stem cells exist in the rat and human glands that are capable of differentiating to the other major cell types of the mammary parenchyma, and that during the carcinogenic process they generate genetically unstable cells which lose their ability to differentiate and attempt to maximise their intrinsically slow growth rate.
The patterns of genetic change, clonal evolution, natural history and latency are very different in the paediatric leukaemias compared with adult epithelial cancers but are similar to those in other childhood cancers of mesenchymal stem cell origin. This distinction has a biological logic in the context of the selective pressures for clonal emergence in different developmental and cellular contexts and has a major impact on curability. Most childhood leukaemias and some other mesenchymal stem cell tumours are of fetal origin and can metastasize without corruption of restraints on cell proliferation or bypassing apoptosis. In marked contrast to most invasive or metastatic epithelial carcinomas in adults, these former cancers then retain sensitivity to therapeutic apoptosis. Moreover, their abbreviated and less complex evolutionary status is associated with less genetic diversity and instability, minimising opportunity for clonal selection for resistance. A minority of leukaemias in children and a higher fraction in adults do, however, have genetic alterations that bypass cell cycle controls and apoptosis imposition. These are the 'bad news' genotypes. The cellular and molecular diversity of acute leukaemia impacts also on aetiology. Paediatric acute leukaemias can be initiated prenatally by illegitimate recombination and fusion gene formation in fetal haemopoiesis. For acute lymphoblastic leukaemia (ALL) in children, twin studies suggest that a secondary postnatal molecular event is also required. This may be promoted by an abnormal or delayed response to common infections. Even for a classic case of a cancer that is intrinsically curable by systematic chemotherapy i.e. childhood ALL, prevention may turn out to be the preferred option.
The patterns of genetic change, clonal evolution, natural history and latency are very different in the paediatric leukaemias compared with adult epithelial cancers but are similar to those in other childhood cancers of mesenchymal stem cell origin. This distinction has a biological logic in the context of the selective pressures for clonal emergence in different developmental and cellular contexts and has a major impact on curability. Most childhood leukaemias and some other mesenchymal stem cell tumours are of fetal origin and can metastasize without corruption of restraints on cell proliferation or bypassing apoptosis. In marked contrast to most invasive or metastatic epithelial carcinomas in adults, these former cancers then retain sensitivity to therapeutic apoptosis. Moreover, their abbreviated and less complex evolutionary status is associated with less genetic diversity and instability, minimising opportunity for clonal selection for resistance. A minority of leukaemias in children and a higher fraction in adults do, however, have genetic alterations that bypass cell cycle controls and apoptosis imposition. These are the 'bad news' genotypes. The cellular and molecular diversity of acute leukaemia impacts also on aetiology. Paediatric acute leukaemias can be initiated prenatally by illegitimate recombination and fusion gene formation in fetal haemopoiesis. For acute lymphoblastic leukaemia (ALL) in children, twin studies suggest that a secondary postnatal molecular event is also required. This may be promoted by an abnormal or delayed response to common infections. Even for a classic case of a cancer that is intrinsically curable by systematic chemotherapy i.e. childhood ALL, prevention may turn out to be the preferred option.
The Keystone Symposia stem cell conference focused on the biological nature of self-renewing cell populations that exist in special regulatory niches and form other cell types that enable maintenance of tissue function, repair and, in some cases, regeneration. Adult stem cells are present in most, if not all tissues, and their regulation as renewing populations, the nature of the niche and the factors driving decisions for differentiation in primary pathways remain the dominant interest in the field. The more vexed question concerning possible transdifferentiation of adult stem cells from one tissue type to another has become focused on the role of fusion and whether this is a recapitulation of normal processes in embryonic and adult development. The possible linkage of cancer phenotypes with stem cells and downstream progenitor cell types through loss of regulatory influences in renewal, expansion and lineage commitment is a rapidly growing interest. Pluripotent embryonic stem (ES) cells and their maintenance and directed differentiation into a variety of tissue types remains an optimistic field of research in which some debate exists about true pluripotency of adult stem cells. The role of epigenetic influences on differentiation and development has drawn on data from nuclear transfer studies in cloning the whole organism and in ES cell production. The formation of germ cells and their renewal and differentiation was also a major interest of the symposium.
Increased interest in the therapeutic use of human stem cells has emerged following significant progress in ongoing research. The cloning of a sheep, the isolation of human embryonic stem cells, and the discovery that adult stem cells may be reprogrammed taken together give substance to hopes that novel principles of treatment may be developed for a variety of serious conditions. Embryonic stem cells are derived from pre-embryos at the blastocyst stage and may give rise to all bodily tissues and cells. Animal models have demonstrated that embryonic stem cells when transplanted into adult hosts may differentiate and develop into cells and tissues applicable for treatment of a variety of conditions, including Parkinson's disease, multiple sclerosis, spinal injuries, cardiac stroke and cancer. Transplanted embryonic stem cells are exposed to immune reactions similar to those acting on organ transplants, hence immunosuppression of the recipient is generally required. It is, however, possible to obtain embryonic stem cells that are genetically identical to the patient's own cells by means of therapeutic cloning techniques. The nucleus from a somatic cell is transferred into an egg after removal of the egg's own genetic material. Under specific condition the egg will use genetic information from the somatic cell in organising the formation of a blastocyst which in turn generates embryonic stem cells. These cells have a genetic composition identical to that of the patient and are suitable for stem cell therapy.
A seventy-one year-old woman suffered from Stage IIIb advanced breast cancer complicated with direct thoracic invasion and skin eruption. An indwelling intra-arterial catheter was inserted into the subclavian artery for the administration of anti tumor agents. After three courses of neoadjuvant chemotherapy combined with G-CSF and/or PBSCT reinfusion, the breast cancer revealed a remarkable size reduction and was absent from direct thoracic and pectoral muscle, invasion within the physical status and visual analysis by CT scan. Thereafter, the patient underwent a radical mastectomy. In the pathological findings of the operation specimen, despite a remarkable tumor collapse, the microscopic invasion remained in the shallow layer of the pectoral muscle. Thus, the patient should be given additional postoperative irradiation. The patients has had six months of stable tumor-free survival since the mastectomy.
Treatment of advanced breast cancer with autologous stem cell transplantation is limited by a high probability of disease relapse. In clinical trials, interleukin 2 (IL-2) alone can expand natural killer (NK) cells in vivo and increase their cytotoxic activity against breast cancer cell lines, but this increase is modest. Understanding the mechanisms that mediate NK cell lysis of breast cancer targets may lead to improvements of current immunotherapy strategies. NK cells from normal donors or patients receiving subcutaneous IL-2 were tested in cytotoxicity assays against five breast cancer cell lines. The role of adhesion molecules and antibodies that interact through Fc receptors on NK cells was explored. NK cell lysis of breast cancer targets is variable and is partially dependent on recognition through ICAM-1 and CD18. While blocking CD2 slightly decreased cytotoxicity, contrary to expectations, an antibody against CD58 (the ligand for CD2), failed to block killing and instead mediated an increased cytotoxicity that correlated with target density of CD58. The CD58 antibody-enhanced killing was dependent not only on FcRgammaIII but also on CD2 and ICAM-1/CD18. To further elucidate the mechanism of this CD58 antibody-dependent cellular cytotoxicity (ADCC), another antibody was tested. Trastuzumab (Herceptin), a humanized antibody against HER2/neu, mediated potent ADCC against all the HER2/neu positive breast cancer targets. Unlike CD58 antibody-mediated ADCC, Herceptin ADCC was minimally affected by blocking antibodies to CD2 or ICAM-1/CD18, which suggests a different mechanism of action. This study shows that multiple mechanisms are involved in NK cell lysis of breast cancer targets, that none of the targets are inherently resistant to killing, and that two distinct mechanisms of ADCC can target immunotherapy to breast cancer cells.