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Expression of estrogen receptor (ER) is a helpful predictor of response to endocrine therapy and disease free survival in breast cancer patients. The presence of variant estrogen receptors has been demonstrated at the RNA/DNA level and might represent an escape of tumors from hormonal control mechanisms. However, the demonstration that the corresponding peptides do exist is a real challenge. Denaturing polyacrylamide gel electrophoresis (SDS-PAGE) of covalently bound [3H]tamoxifen aziridine ([3H]TAZ) to ER demonstrates a specific, multiband peptide pattern recognized by anti-ER monoclonal antibodies (anti-ER Mo Abs). The native 66 kDa ER form identified through its hormone binding domain by the H-222 Mo Ab was the most prominent one followed by 50, 35, and 28 kDa forms on fluorography. Such patterns from early human breast tumors were compared to the ones of more advanced disease, namely large primary breast cancers, metastatic lymph nodes, and soft tissue relapses: in these cases, molecular forms of 43 and 35 kDa were identified with a remarkable consistency. The 43 kDa peptide was more frequently identified by the H-226 Mo Ab (which maps a region near the DNA binding domain)-albeit with low labeling intensity as compared to H-222 Mo Ab. In addition, the 43 kDa peptide was inversely correlated to ER levels. This altered ER or related peptide could potentially be a marker of biologically aggressive breast tumors., Comparative Study, Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

SCOPUS: ar.j, info:eu-repo/semantics/published

SCOPUS: ar.j, info:eu-repo/semantics/published

We examined the estrogen receptor measurement in 265 human breast cancer cytosols by using a specific method based on [3H]tamoxifen aziridine labeling, sequential immunoadsorption with an antiestrogen receptor monoclonal antibody (H-222), sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and autoradiography. These new tools of molecular endocrinology revealed an impressive estrogen receptor molecular polymorphism. Given the recent finding of a similar estrogen receptor polymorphism at the messenger RNA level by several laboratories, it is tempting to speculate about its possible biological significance. To gain insight into the potential clinical relevance of this polymorphism in terms of breast cancer hormone dependence, we compared the 265 cytosols for their [3H]tamoxifen aziridine- and [3H]estradiol-binding capacities using the above-mentioned method and the conventional dextran-coated charcoal assay. We failed to identify a specific [3H]tamoxifen aziridine electrophoretic pattern with respect to the tumor estrogen receptor content as measured by the dextran-coated charcoal assay. However, an excellent correlation overall was found between the intensities of both labeling methods. Some tumors were positive for only one of these two ligands. It will be clinically important to see whether the tumors positive for [3H]tamoxifen aziridine only correspond to the small subset of tumors (10%) which respond to tamoxifen treatment despite very low estrogen receptor levels, as measured by the dextran-coated charcoal technique., Comparative Study, Journal Article, info:eu-repo/semantics/published

Human mammary carcinoma cell lines (MCF‐7) were analysed for their hormone sensitivity before and after transfection with a v‐Ha‐ras oncogene or with a neomycin‐resistance gene followed by selection in vitro or in vivo. Our aim was to test how the expression of the ras oncogene would influence the estradiol sensitivity of MCF‐7 cells. In culture, MCF‐7 cells expressing the viral p21 oncogene product, as compared to parental MCF‐7 cells and their control derivatives, showed lower levels of a 67‐kDa estrogen receptor. Progesterone receptors, however, remained sensitive to up‐regulation by estrogens. The oncogene‐expressing cells were less sensitive than all controls to stimulation of proliferation by 10‐8M estradiol or to inhibition of proliferation by 2‐CH3‐4‐OH tamoxifen, and this was not dependent upon the type of culture medium used. After s. c. or i. p. injection into female athymic nude mice, ovariectomized or left intact, the growth of MCF‐7 cells expressing the ras oncogene product and of all control cells was sensitive to stimulation by estrogen supplementation. Conversely, cell lines derived from tumors generated with long latency in untreated athymic nude mice by v‐ras‐expressing MCF‐7 cells showed efficient formation of quickly growing tumors in the absence of estrogen supplementation. No differences were observed in invasion and metastasis of the different MCF‐7 cell types injected into athymic nude mice that were supplemented with estrogens or not. Copyright © 1990 Wiley‐Liss, Inc. A Wiley Company, SCOPUS: ar.j, FLWNA, info:eu-repo/semantics/published

Since the binding sites of hormone receptors may be similar to those of antihormone antibodies, we wondered whether the former might not be recognized by the idiotypic network. To test this hypothesis we investigated the interaction of plasma immunoglobulin G (IgG) with the binding sites of estrogen receptors (ER) from uterine or mammary tissue. Using ER isolated from uterine cytosol we found that IgG from normal subjects shifted the position of purified receptor in sucrose gradients and displaced [3H]estradiol (E2) from its receptor-binding sites. Equilibrium studies revealed competitive inhibition by IgG of E2 binding to the ER. IgG isolated by adsorption on a rat uterine cytosol-Blue B matrix gel column also bound to the ER, and this binding was inhibited by an excess of E2. After an 18-h exposure of MCF-7 mammary carcinoma cells in monolayer culture to IgG (2 mg/ml), Scatchard analysis of [3H]E2 binding revealed a reproducible decrease in the available receptor sites from 2.52 +/- 0.56 (+/- SEM) to 0.68 +/- 0.48 fmol/microgram DNA (n = 10). This effect was selective, since enriched anti-ER IgG obtained by adsorption on purified receptor was 20 times more potent than total IgG, whereas IgG identically prepared but not retained by affinity chromatography had no activity. Exposure of the cells to the IgG for 45 min also revealed, as with isolated ER, specific competition of the IgG with E2 for the E2-binding sites; the Kd increased from 10.5 +/- 1.6 to 27.5 +/- 7.2 X 10(-11) M (n = 7). Enriched antireceptor IgG was a 20 times more effective competitor, and the IgG not retained by affinity chromatography had no activity. In conclusion, our observations indicate the presence of ER on the cell surface, interaction of ER with IgG from plasma of normal subjects, and competitive antagonism of these IgG with E2 uptake leading to a decrease in effective ER concentrations., Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

To understand ectopic hormone secretion in cancer we compared the plasma concentrations of the hCG-like substance in normal nonpregnant subjects and in women with breast cancer. In 45 normal men the plasma concentrations did not vary with age (median, 5 pg/ml; range, less than 3-169) whereas in 45 normal women they increased after menopause (median, 48 pg/ml; range, less than 5 -569, n = 20, P less than 0.0001). In 56 women with breast cancer the plasma concentrations of the hCG-like substance after menopause were much higher than in normal women (median, 202 pg/ml; range, 14-1561; n = 35; P less than 0.001), with no abnormally high pituitary gonadotropin values and no relationship with the tumor burden (same median after mastectomy, 198 pg/ml; n = 21). This hCG-like substance was glycosylated and similar to standard hCG according to molecular size, ionic strength, and immunoreactivity. Our data are compatible with the following conclusions: 1) the plasma concentration of the hCG-like substance is normally very low but dependent on gonadal function in women. Its source might be the pituitary gland or peripheral tissues. 2) Its concentration is much increased in postmenopausal women with breast carcinoma. This increase is found with normal pituitary gonadotropin values and is independent of the tumor burden, suggesting it is of extrapituitary and nontumoral origin., Comparative Study, Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

SCOPUS: ar.j, info:eu-repo/semantics/published

SCOPUS: ar.j, info:eu-repo/semantics/published

SCOPUS: ar.j, info:eu-repo/semantics/published

SCOPUS: ar.j, info:eu-repo/semantics/published

Sign.: []3, 1-304, Las h. de lám. son grab. litogr.: "Imp. Simonan & Toovey Bruxelles"