onapristone and hydroxyflutamide

The oestrogen receptor is fundamental to the growth and survival of the rat pituitary tumour cell line, GH(3). Our previous studies have shown that antioestrogens such as RU 58668 and ZM 182780 will reduce the rate of cell division and also induce cell death. Death of these cells in response to antioestrogen treatment appears to be due to a heightened sensitivity to reactive oxygen species (ROS). As part of a study to determine the cross-talk between steroid receptor systems in these cells, we have observed that the glucocorticoid, dexamethasone (Dex), inhibits antioestrogen-induced cell death. Cell death induced by H(2)O(2) is enhanced by ZM 182780 and this effect is also blocked by Dex. As apoptotic cell death in a number of systems involves an early loss of mitochondrial membrane potential (DeltaPsi(m)), we have performed detailed studies on the time-course of DeltaPsi(m) loss in relation to the loss in cell membrane function. These studies have indicated that a loss of DeltaPsi(m) parallels a loss of cell membrane function - this is more characteristic of necrosis than of apoptosis. From microscopic observations of these cells in response to H(2)O(2), it has been noted that early cell membrane blebbing, induced by H(2)O(2), is blocked in the presence of ZM 182780. Cell membrane blebbing can precede necrosis as well as apoptosis and it is thought to involve cytoskeletal changes, for which localised glycolytic reactions provide ATP. These observations, together with those showing that removal of glucose, but not inhibition of mitochondrial function, enhances ROS-induced cell death, prompted studies on the glycolytic pathway. As a strong candidate mechanism, it would appear that, via an effect on one of the rate-limiting glycolytic enzymes, glyceraldehyde-3-phosphate dehydrogenase, Dex is able to overcome the antioestrogen-enhanced loss of glycolytic function following exposure of cells to ROS. This report contributes to the growing body of evidence showing that glucocorticoids provide a survival advantage to both normal and tumour cell types.

Topics: Adenosine Triphosphate; Cell Death; Dexamethasone; Estradiol; Estrogen Receptor Modulators; Estrone; Flow Cytometry; Flutamide; Fulvestrant; Glucocorticoids; Glyceraldehyde-3-Phosphate Dehydrogenases; Gonanes; Humans; Hydrogen Peroxide; Microscopy, Fluorescence; Mifepristone; Pituitary Neoplasms; Reactive Oxygen Species; Receptor Cross-Talk; Receptors, Cell Surface; Transfection; Tumor Cells, Cultured

Estrogenic activities of testosterone (T) and 5a-dihydrotestosterone (DHT) were detected and measured by using their specific stimulatory effects on alkaline phosphatase (AP) activity in human endometrial adenocarcinoma cells of the Ishikawa Var-1 line. These two physiologic androgens were able to induce, at microM concentrations, estrogenic effect believed to be mediated by the estrogen receptor (ER) since the antiestrogens ICI-164384 and 4-hydroxytamoxifen (OHTam), but not the antiandrogens hydroxyflutamide (OHFl) or cyproterone acetate (CPA), reversed that effect. By using another in vitro bioassay, based on the progestin-specific stimulation of AP activity in cells of the T47D human breast cancer line, progestagenic activity was detected and measured in T, DHT and three synthetic androgens: nandrolone (19-nortestosterone). 7 alpha-methyl 19-nortestosterone (MENT) and mibolerone (7 alpha, 17 alpha-dimethyl 19-nortestosterone) (DMNT). While progestagenic effects of T and DHT required relatively high concentrations (microM levels), the synthetic androgens stimulated AP activity at nM or pM levels. These effects seem to be mediated by the progesterone receptor (PR), since they are completely abolished by the antiprogestins RU-486, ZK-98299 and ZK-112993, but not by the antiandrogen OHFl. These simple in vitro bioassays, expressing biological effects of the test compounds in human cells in culture, revealed dual or multiple hormonal activities coexisting in a single compound and provide quantitative information of considerable pharmacological importance concerning the complex actions of drugs.

Topics: Adenocarcinoma; Alkaline Phosphatase; Androgen Antagonists; Androgens; Breast Neoplasms; Cyproterone Acetate; Endometrial Neoplasms; Estradiol; Estrogen Antagonists; Female; Flutamide; Gonanes; Humans; Mifepristone; Polyunsaturated Alkamides; Progestins; Tamoxifen; Testosterone; Testosterone Congeners; Tumor Cells, Cultured

In addition to their antiprogestational activity, the antiprogestins RU486, ZK98.299 and ZK98.734 possess varying antiglucocorticoid as well as androgen-like or antiandrogen-like properties in human mammary cancer cells. The human mammary cancer cell line MFM-223, which contains only androgen receptors, was used as a model to investigate androgen receptor mediated effects of these antiprogestins. Proliferation of MFM-223 cells is inhibited by androgens and does not respond to oestrogens, progestins and glucocorticoids. As shown in proliferation assays, ZK98.734 was a strong inhibitor of cell proliferation. This effect was antagonised by the antiandrogen hydroxyflutamide. ZK98.734 was found to displace [3H]R1881 from the androgen receptor in MFM-223 cells, substantiating the involvement of the androgen receptor. The antiprogestin ZK98.299 failed to influence the proliferation of MFM-223 cells. ZK98.299 did not bind to the androgen receptor and was devoid of androgenic or antiandrogenic activity. RU486 bound to the androgen receptor. It was a weak inhibitor of MFM-223 cell proliferation, but the inhibition of proliferation by RU486 was not antagonised by hydroxyflutamide. This effect was probably not mediated by the androgen receptor. RU486 had antiandrogenic activity in this cell line, as it antagonised the inhibitory effect of dihydrotestosterone at a 100-molar excess. These results were confirmed by transfection experiments with an MMTV-CAT construct in the same cell line, demonstrating the biological function of the ZK98.734-androgen receptor complex. ZK98.299 and RU486 were not able to induce CAT activity. The different androgenic or antiandrogenic properties of the antiprogestins investigated should be considered when selecting antiprogestational properties of the antiprogestins investigated should be considered when selecting antiprogestational compounds for clinical applications, as a partial androgenic activity may be of benefit in breast cancer but can have undesired side-effects in other diseases.

Topics: Androgen Antagonists; Antineoplastic Agents; Binding, Competitive; Breast Neoplasms; Cell Division; Dihydrotestosterone; Estrenes; Flutamide; Gonanes; Humans; Mifepristone; Models, Biological; Progestins; Receptors, Androgen; Transfection; Tumor Cells, Cultured