Effects of Steroid Hormones and Antihormones in Cultured Cells1)

Publisher Website
Google Scholar
Abstract
Mouse L-929 fibroblasts contain androgen (AR), estrogen (ER) and glucocorticosteroid receptors (GR). The addition of androgens and estrogens (10 to 50 nM) to the culture medium stimulated cell growth and this growth stimulation was inhibited when the corresponding anti-hormones (cyproterone acetate or tamoxifen, 100 nM) were present at the same time. Glucocorticosteroids (10 to 100 nM) had negative effects on cell growth leading even to cell death over 1 µM concentrations. The addition of a new antiglucocorticosteroid RU 486, inhibited the negative effects of glucocorticosteroids. RU 486 displays also anti-progesterone activity, but as L-929 cells have no progesterone receptor, only the antiglucocorticosteroid action of this new compound was studied. Cell adhesiveness to culture plates was increased by androgen or estrogen, but decreased by glucocorticosteroid and again, the corresponding anti-hormones abolished these positive or negative effects. All these observations can be made in serum-free culture medium supplemented with insulin but not with other hormones, proteins or growth factors. Cyproterone acetate, tamoxifen and RU 486 have specific affinity for AR, ER and GR, respectively. After incubation of whole cells with 3H-tamoxifen or 3H-RU 486, accumulation of either estradiol or glucocorticosteroid receptor complexes in the nuclear fraction of the cell was observed. A tamoxifen-resistant clone of L-929 cells was selected in serum-free medium. This variant had about 50% less ER than tam-sensitive L-929 cells and also less specific antiestrogen binding sites which were found in the particulate fraction of the cells. Shionogi SC-115 mammary cancer cells contain AR and ER. In the presence of testosterone (50 nM) a considerable difference of cell growth was observed. Testosterone increased cell proliferation, and the anti-androgen cyproterone acetate (100 nM) completely inhibited this growth stimulation. RU 486 (100 nM) showed also some antagonistic effect on androgen induced cell growth. The shape of cells cultured with or without androgens was completely different. In the presence of testosterone, clonal growth of the cells was observed with no contact inhibition, whereas in the absence of hormone, cells formed a monolayer. No clonal growth was observed when cyproterone acetate (100 nM) was present at the same time as testosterone in the culture medium. Both testosterone and cyproterone acetate were bound to AR. In the murine thymoma cell lines W7TB and T1M1b, RU 486 is a strong antagonist of the glucocorticosteroid induced cytolytic response. RU 486 had high affinity for GR of W7TB cells, but the complex formed had lower ability than the dexamethasone-receptor complexes to accumulate in the nuclear fraction. This difference may be related to decreased affinity for DNA (Bourgeois et al., 1984).