Induction of progesterone receptor in an estrogen, progesterone receptor-negative breast cancer cell line

Estrogen receptor-negative/progesterone receptor-positive Evsa-T mammary tumor cells: a model for assessing the biological property of this peculiar phenotype of breast cancers

In 1986 we reported the appearance of a progestin binding protein in the human breast cancer cell line Evsa-T, originally described as lacking both estrogen and progesterone receptors (ER and PR). In this report we show that PR of this cell line displays a binding affinity for [3H]ORG 2058 and a sucrose gradient sedimentation profile similar to those ascribed to PR from MCF-7 or T47D breast cancer cell lines. PR from Evsa-T cells is down-regulated by the progestin R-5020 as well as by the two antiprogestins, ZK 112.993 and ZK 98.299, but does not confer growth sensitivity to these compounds. ER remains undetectable by ligand binding assay, enzyme immunoassay and northern blotting. Our Evsa-T clone could be a valuable model for assessing the mechanisms leading the ER-/PR+ phenotype occurring occasionally in breast cancers and frequently in meningiomas.

Increased autocrine production of insulin-like growth factor II (IGF-II) alters serum sensitivity of MCF-7 human breast cancer cell proliferation

Regulation of the growth of breast cancer cells is the result of a complex interaction between steroid hormones and growth factors, and in particular of oestrogen and insulin-like growth factors (IGF). Alteration of any one mitogenic component can affect the cell response to other pathways. Previous work has shown that increased autocrine production of IGF-II from a transfected inducible expression vector can result in reduced oestrogen sensitivity of growth of MCF-7 human breast cancer cells. This report describes alterations to non-oestrogen regulated pathways of cell growth following enhanced IGF-II expression in these transfected MI7 cells. Serum sensitivity of cell growth in the absence of oestrogen was found to differ between MI7 and untransfected MCF-7 cells, in that growth of MI7 but not MCF-7 cells was strongly inhibited by high serum levels. Increased serum had no effect on levels of IGF-II mRNA, IGFIR, IGFBP4 mRNA, or IGFBP secreted in MI7 cells. However, growth inhibition by serum in MI7 cells could be overcome by increasing levels of IGF-II in the serum or by removal of IGFBP onto polycarbonate membranes. Thus, the growth inhibition by serum in MI7 cells is concluded to result from the increased levels of IGFBP added with higher serum. This would support an inhibitory role for IGFBP on growth of breast cancer cells when cell growth is being driven by IGF pathways in the absence of oestrogen, and would suggest that cellular sensitivity to such factors can depend on levels of endogenous IGF production.

Evidence for abrogation of oncogene-induced radioresistance of mammary cancer cells by hexadecylphosphocholine in vitro

Hexadecylphosphocholine (HePC), an experimental and clinical antitumour agent of the alkyllysophospholipid group, was tested for its radiosensitising effect on a panel of nine human mammary cancer cell lines in vitro. Growth inhibition by ionising radiation and recovery from it were not influenced by pretreatment with HePC in most cases, except for two cell lines expressing an activated ras oncogene. In the latter we found an enhanced radioresistance that was abolished by pretreatment with HePC. Our results suggest that HePC may act as a radiosensitiser for cells carrying an activated ras oncogene.

Immunohistochemical analysis of the topographical relationship between the estrogen- and progesterone receptor in five human breast cancers. A simultaneous demonstration of both nuclear receptors in the same section by using a computer-assisted image processing

A technique is described which allows precise assessment of the topographical relationship between the estrogen receptor (ER) and the progesterone receptor (PR) in the same histological section. It is based on the analysis of the results of immunohistochemical double staining by computer-assisted image processing. Five human ductal breast cancers were examined. The simultaneous demonstration of both receptors consists in the following principal steps: The primary antisera against the ER (monoclonal rat antibody) and the PR (monoclonal mouse antibody) are incubated simultaneously, but only the anti-ER antibody is demonstrated in the first staining step by using a goat anti-rat antibody as the linking antibody and the PAP complex from the rat, both antisera from the ER-ICA kit. The result is stored as a digitized grey image ("1. object image"). Then the colored end product and the residual peroxidase activity of the PAP complex are removed. In the second staining sequence the anti-PR-antibody is demonstrated by using a rabbit anti-mouse antibody as the linking antibody and the PAP complex from the mouse. The result is exactly positioned and also stored as a digitized grey image ("2. object image"). Though antibodies raised in different species were used, cross-reactivity could not be avoided. Grey values generated by cross-reactivity between the different antibody systems are evaluated in negative controls and are eliminated in the object images. The remaining (specifically stained) structures of both object images are copied into a final image so that the topographical relationship of the ER and the PR becomes obvious. The results show that in the five carcinomas investigated three types of receptor-positive tumour cells can be distinguished: Cells which coexpress the ER and the PR (1), cells which express either the ER (2) or the PR (3). The number of tumour cells showing one of these expression patterns varies from tumour to tumour.

Estrogen control of lactate dehydrogenase isoenzyme-5 in human breast cancer

Determinations of estradiol receptor (ER), progesterone receptor (PR), total lactate dehydrogenase activity (LDH) and electrophoretic separation of LDH isoenzymes were performed in cytosols from 118 samples of primary infiltrating ductal mammary carcinoma. ER + PR+ tumors demonstrated a significant increase in the proportion of the LDH muscle-type isoenzyme (LDH5) as compared to ER-PR- samples (p less than 0.002). Tumors lacking one of the receptors presented intermediate LDH5 percentages. As total LDH activity bore no relation to either the presence or absence of receptors, the increased proportion represents an absolute elevation of LDH5, suggesting that LDH5 may be a promising hormone-dependence marker. As an in vitro model to study whether LDH5 was induced by estradiol via ER, we have used two human breast cancer cell lines, MCF-7 and T47D. In both cell lines LDH5 was the sole isoenzyme. Total ER and PR have been determined by a whole-cell method. In MCF-7 cells (with high ER levels), after incubation with 10(-10) M estradiol, maximal induction of LDH had already been achieved. In relation to T47D (low ER levels) estradiol did not evoke an induction of LDH5 at any concentration examined. In MCF-7 cells, the level of LDH5 induction paralleled processing of ER. The processing effect was rapid, beginning within 5 min of estradiol addition, and was completed within 1 hr. With 10(-6) M tamoxifen, LDH5 induction was suppressed and this effect was reversed by estradiol. Such antiestrogenic effects of tamoxifen on LDH5 have not been observed in T47D cells. Agonistic effects of low doses of tamoxifen on LDH5 were not observed. Our studies suggest that estrogen stimulation of LDH5 involves ER.

Effects of danazol on incidence of progesterone and oestrogen receptors in benign breast disease

Results from a continuing clinical trial in benign breast disease indicate that danazol may induce progesterone receptors and that this effect persists after treatment. In women given danazol the number of biopsy specimens that were positive for progesterone receptors rose from 14 out of 31 before treatment to 23 out of 30 at the end of six months' treatment and remained raised at 21 out of 31 six months later. The number of biopsy specimens that were positive for oestrogen receptors rose transiently from eight out of 31 to 12 out of 30 and then fell to six out of 31. A satisfactory clinical response was achieved in 26 of the 31 patients but was maintained in only 11 six months or more after the end of treatment. It was only in this group that a significant and long-standing increase in progesterone receptors was observed. These findings suggest that in some women with benign breast disease who have been treated with danazol changes occur that may have long term benefit.