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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism by which pharmacological concentrations of estrogen can paradoxically inhibit the growth of human breast cancer is unknown. We have selected for a variant line of MCF-7 which may help to understand this process. The variant was selected by exposing MCF-7 cells to high-specific-activity 16 alpha-[125I]iodoestradiol. These cells were viably frozen for two isotopic half-lives, defrosted once, then reexposed to 16 alpha-[125I]iodoestradiol to allow maximal radiation damage mediated by isotope associated with binding sites. This cell line (113) is one of 55 lines cloned from MCF-7 cells that survived this treatment. The growth response to estradiol of the 113 breast cancer cells grown in monolayer is normal for 4 to 6 days, and then the cell number plateaus as the cells appear to round up and detach. Concomitantly, a decrease in [3H]thymidine incorporation occurs. The cells cannot be rescued by removing estradiol from the medium. The inhibition is dose dependent and can be seen in concentrations of estradiol as low as 10(-10) M. The 113 cells are also inhibited by antiestrogens. They have normal levels of estrogen receptors which bind to DNA cellulose with activation. Progesterone receptors are estrogen inducible, although the levels are one-third that of wild-type MCF-7 cells. The morphological changes determined by electron microscopy of estrogen-treated cells are typical of degenerative cells. To investigate the possibility that inhibitory factors are secreted into the medium by 113 cells, conditioned medium from estrogen-exposed 113 cells is added to normal MCF-7 and 113 cells. No decrease in [3H]thymidine incorporation compared to controls is observed. When the secreted proteins are labeled with [35S]methionine and analyzed by sodium dodecyl sulfate-acrylamide gels, no major differences are apparent in the 113 and MCF-7 cells. Thus, the source of the defect is still unknown. It remains to be seen if the growth-inhibitory effects of 17 beta-estradiol on this cell line are receptor mediated or related to specific gene products which can be identified.
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PMID:Isolation and characterization of an estrogen-inhibited variant derived from the MCF-7 breast cancer cell line. 674 9

The effects of steroid hormones on the colony forming activity of a human breast cancer cell line (MCF-7) were studied. Endrogeneous estrogens in the fetal calf sera used for culture were deprived using the dextran-coated charcoal, and only batches of E2-deprived serum were chosen with which there was a significant increase in the plating efficiency after E2 (estradiol-17 beta, 10(-8) M) treatment. Progesterone showed little effect on the growth of the cells. not being influenced by the addition of E2. The capacity of the cells to form colonies was stimulated by androgens (5 alpha-dihydrotestosterone, testosterone) only in the absence of E2. Dexamethasone had suppressive effects regardless presence of E2. Thus, MCF-7 cells showed variable responses to these steroid hormones, although the cells have specific receptors to the hormones. This colony formation method of MCF-7 cells may be a useful model system for the study of hormonal and non-hormonal anti-cancer agents.
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PMID:[Evaluation of steroid hormone sensitivity of human breast cancer cells in culture (MCF-7) by a colony formation method]. 687 Mar

We have analyzed the effect of estradiol and of two classes of antiestrogens on the morphology of the MCF7 human breast cancer cell line by scanning and transmission electron microscopy. Estradiol progressively increased the number and the length of microvilli at the cell surface. The density of the microvilli network increased between 2 and 11 days of estrogen treatment, while the cells became more granular and less tightly attached to the surface of the dish. Estradiol also progressively transformed cells into secretory cells containing, at Day 2, large, clear mitochondria and, at Day 4, rough endoplasmic reticulum and Golgi complex. At Day 6, secretory granules (diameter, 0.2 microM), which mainly contained glycoproteins, were first developed in the cytoplasm. By Day 8, they were concentrated at the cell membrane and being liberated into the medium. Larger granules (diameter, 0.8 microM), which probably contained lipids, were obtained later (Day 11). Cell cultures in 10% fetal calf serum not treated by charcoal contained secretory granules. The modifications were induced by physiological concentrations of estradiol but not 5 alpha-dihydrotestosterone. Progesterone (10 nM for 8 days) completely inhibited the effect of estradiol on the microvilli and secretory activity. Tamoxifen or hydroxy-tamoxifen did not induce secretory activity but did alter the cell morphology compared to control cells. The effects of estradiol were observed in other estrogen receptor-positive breast cancer cell lines (ZR 75-1, T 47 D) but not in an estrogen receptor-negative cell line (BT 20). This morphological evidence that estrogens modify the cell surface of breast cancer cells in culture and transform them into "secretory cells" complements evidence that a molecular weight of approximately 50,000 into the culture medium (Cell, 24: 352-362, 1980). (The molecular weight was found first to be 46,000. It seems to be closer to 52,000 in a 10% polyacrylamide gel and by using the NEN-labeled proteins as molecular weight markers.
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PMID:Effect of estradiol on the ultrastructure of the MCF7 human breast cancer cells in culture. 705 9

Receptor assay results were compared with the ultrastructure of 127 breast cancers (112 primary tumors, six recurrent lesions, nine metastases). Tumors were considered to be receptor positive if the receptor levels were greater than or equal to 15 fmol/mg of soluble tissue protein. Most breast cancer had heterogenous cells with different grades of ultrastructural differentiation. a prevalence of well-differentiated cancer cells and an abundance of intracytoplasmic vacuoles had a significant correlation with a positive estrogen receptor status. The correlation was better than between malignancy grades and receptor content. The type of breast cancer and the menopausal status bore no relation to receptor content. Progesterone receptors were found in well-differentiated tumors of low malignancy.
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PMID:Correlations of the receptor content and ultrastructure of breast cancer cells. 712 99

Tumor cell biology and growth-kinetics of human breast cancer are reviewed with reference to the different action mechanisms of main antitumor drugs. Particular emphasis is given to pharmacokinetics, dosage, mode of administration, effectiveness and side-effects of drugs most commonly used in breast cancer. The importance of tumor Estrogen and Progesterone Receptor assay for the therapy planning is considered and a short review of estrogens, androgens, progestins, antiestrogens, corticoids and aminogluthetimide is presented. The rationale for combined chemotherapy and/or hormonotherapy in breast cancer is finally discussed.
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PMID:Introduction to chemotherapy and antineoplastic pharmacology in breast cancer. 716 62

We have studied the effect of steroids on cell proliferation in two continuous cell lines derived from rat mammary tumors induced by 7, 12-dimethyl-benz (a) anthracene (DMBA) and N-nitrosomethylurea (NMU). These cell lines contain high concentrations of glucocorticoid and androgen receptors but no estrogen and progesterone receptors as previously shown (1). The cell proliferation was evaluated by measuring [3H] thymidine incorporation into DNA, cell number, and DNA content. Dexamethasone was found to markedly stimulate cell proliferation in a dose-dependent manner, suggesting that it was acting via the glucocorticoid receptor. The effect of 5 alpha-dihydrotestosterone (DHT) was weaker since a stimulation of [3H] thymidine incorporation was contrasted by the absence of a constant increase of cell proliferation. Progesterone partially stimulated NMU cell growth and totally inhibited the stimulatory effect of dexamethasone in both cell lines. The synthetic progestin R5020 displayed a similar activity to that of progesterone. These results show that progestins can directly modulate the growth of mammary cancer cells even in the absence of progesterone receptor by interacting on the glucocorticoid receptor. We conclude that progestins act mostly as partial agonist-antagonists of glucocorticoids in these two rat mammary adenocarcinoma cell lines.
Breast Cancer Res Treat 1981
PMID:Growth regulation of two rat adenocarcinoma cell lines by dexamethasone and progesterone. 734 82

Human mammary tumor cytosol containing macromolecules which bound 3H-MPA (3H-medroxyprogesterone acetate or 1,2-3H-6 Alpha-methyl-17 alpha-acetoxy-pregn-4-ene-3,20-dione) and 3H-R5020 (6,7-3H-17,21-dimethyl-19-nor-pregna-4,9-diene-3,20-dione) similarly with high affinity (Ka approximately equal to 2 nM-1) and specificity. The progestin-binding components had sedimentation coefficients of about 4S and 7S in sucrose gradients and had approximately the same number of binding sites for Ma and R5020 as revealed by gradient centrifugation and saturation analysis. Among the steroids tested, these components had the highest affinities for progestins and were probably progesterone receptors of human breast cancer. A 4S component of human serum bound 3H-R5020 but not 3H-MPA. With 3H-MPA and 3H-estradiol used as the tracers, the concentrations of progesterone and estrogen receptors have been determined in 236 human breast cancers by saturation analysis. Our results on the receptor content and response of 31 of these tumors to endocrine therapy suggest that progesterone receptor may be a better marker of a hormonally responsive breast cancer.
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PMID:Binding of medroxyprogesterone acetate in human breast cancer. 737 48

A clone of MCF-7 (MCF-7ED), a cell in continuous in vitro cultivation derived from an estrogen-responsive human breast carcinoma, requires estrogen supplementation for progressive exponential (double time: 50--85 h) tumor growth in the mammary fat of athymic mice. The plasma concentration of estradiol which stimulated exponential growth of MCF-7ED corresponded to physiologic premenopausal levels in women. The tumors were carcinomas with murine and MCF-7ED cells intermixed. MCF-7ED cells could be repurified in subcultures of mixed tumors. Comparative studies of breast and non-breast cell lines showed concordance between the presence of estradiol receptor, sensitivity to the anti-estrogen tamoxifen for growth in vitro, and estradiol dependence for tumorigenic growth in athymic mice. Progesterone alone did not stimulate MCF-7ED growth, but acted synergistically with estrogen. Progesterone's action was to decrease tumor latent period, not to increase final tumor incidence or growth rate. Under estrogen-deficient conditions, condsitions approximating postmenopausal status in women, (10(-10) M in plasma), a dormant state was established between MCF-7ED cells and murine mammary stroma which could be maintained several months. The dormant state could be broken by introduction of estradiol, but not progesterone. This system should be useful for defining host and cancer cell determinants in estrogen-responsive breast cancer growth.
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PMID:Estrogen responsive proliferation of clonal human breast carcinoma cells in athymic mice. 745 36

The effect of progesterone (Pg), medroxyprogesterone acetate (MPA), estradiol (E2), dihydrotestosterone (DHT) and dexamethasone (DEXA) was studied on the in vitro growth rate of a progestin-dependent (PD), estrogen-sensitive mammary tumor line originated in an MPA-treated BALB/c mouse (C4-HD), and on its estrogen-resistant variant (C4-HDR). The specificity of hormone action was further investigated using the anti-hormones RU-486 and hydroxyflutamide (FLU). Cell growth was evaluated in epithelial and fibroblast-enriched cultures using 3H-thymidine and/or autoradiography and immunocytochemistry. The results indicate that cell growth is directly stimulated by MPA and Pg at concentrations ranging from 10(-11) to 10(-7) M. RU486 prevented MPA-induced stimulation in concentrations 10 to 100 fold lower than those of MPA. When used alone, it inhibited cell proliferation only in concentrations higher than 10(-11) M. At nM concentrations, neither DEXA nor DHT stimulated 3H-thymidine uptake except DEXA at 100 nM. MPA-induced stimulation was not reverted by micromolar concentrations of FLU. As for E2 (10(-7)-10(-9) M) it prevented MPA stimulation only in cultures of estrogen-sensitive tumors. Progesterone receptors (PR) (475 +/- 115 fmoles/10(5) cells, n = 5) and estrogen receptors (ER) (ND-115 fmoles/10(5) cells, n = 5) were detected only in epithelial-enriched cultures. Serum from 7 day-MPA-treated mice induced a significant increase of 3H-thymidine uptake; an increase was also obtained with serum from untreated ovariectomized animals to which 1 nM-100 nM concentrations of MPA had been added. The stimulatory effect of the exogenous MPA was much lower than that of the serum obtained from MPA-treated animals. It is concluded that MPA stimulates cell growth of primary cultures of MPA-induced PD tumors via PR. The results provide support for a direct effect of MPA which may be mediated or potentiated by serum factors.
Breast Cancer Res Treat 1995 Aug
PMID:Effect of medroxyprogesterone acetate (MPA) and serum factors on cell proliferation in primary cultures of an MPA-induced mammary adenocarcinoma. 764 39

The mechanisms of action of, and resistance to, the steroidal regulators of normal mammary epithelial and breast cancer cell development are only partially understood. A major obstacle to research progress has been the difficulty in supporting physiologically relevant development of normal mammary epithelial cells (MEC) under defined serum-free conditions. A primary culture system was developed in our laboratory that permits nonfunctional rat MEC to undergo extensive proliferation, functional differentiation, as well as multilobular and lobuloductal branching alveolar morphogenesis. In the studies reported here, the contributions of hydrocortisone and progesterone during the coordinate induction of cellular proliferation, organoid morphogenesis, and functional capacity were assessed. Hydrocortisone (0.1-10 microgram/ml) induced alveolar and multilobular branching morphogenesis, suppressed lobuloductal branching morphogenesis, and enhanced casein accumulation. Hydrocortisone also played a role in maintaining alveolar as well as multilobular branching morphogenesis and casein levels. Progesterone (0.01-1 microgram/ml) induced cellular proliferation as well as multilobular and lobuloductal branching morphogenesis, and suppressed casein accumulation. At a supraphysiological concentration (10 micrograms/ml), progesterone inhibited cell growth, alveolar branching morphogenesis, and casein accumulation. MEC cultured without progesterone for up to 1 week retained the ability to respond when subsequently exposed to this steroid. Reversibility studies suggested that progesterone was required for the induction, but not the maintenance of the mitogenic, morphogenic, and lactogenic effects. This physiologically relevant primary culture system can be used to study the factors that regulate steroid responsiveness as well as the cross-talk between steroid and growth factor receptor signaling pathways in normal MEC and breast cancer cells.
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PMID:Hydrocortisone and progesterone regulation of the proliferation, morphogenesis, and functional differentiation of normal rat mammary epithelial cells in three dimensional primary culture. 770 79


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