Altered glucocorticoid binding and action in response to epidermal growth factor in HBL100 cells.
Incubation of adherent human breast epithelial HBL100 cells with epidermal growth factor (EGF) decreased [3H]dexamethasone binding by 35% with no effect on affinity. Maximal inhibition was obtained at 3 nM EGF and the 50% effective dose was 0.2 nM EGF. Decreased dexamethasone binding induced by 3 nM EGF was maximal by 5 min of treatment and, in the continuous presence of EGF, persisted at a constant level over 4 days. The action of EGF was antagonized by 12-O-tetradecanoylphorbol-13-acetate, which did not inhibit dexamethasone binding significantly, and by concanavalin A. In homogenates of EGF-treated cells, decreased dexamethasone binding was observed only in the cytosolic fraction. Saturation dexamethasone binding inhibited the growth rate of HBL100 cells by approximately 50%, but concurrent treatment with EGF overcame this inhibition. The effect of EGF on dexamethasone-inhibited cell growth also was antagonized by 12-O-tetradecanoylphorbol-13-acetate.
D001940:Breast; D002460:Cell Line; D003208:Concanavalin A / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D003907:Dexamethasone / Q000378:metabolism / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D004848:Epithelium / Q000378:metabolism; D005260:Female; D006801:Humans; D007700:Kinetics; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D011965:Receptors, Glucocorticoid; D003208:Concanavalin A; D004815:Epidermal Growth Factor; D003907:Dexamethasone; D013755:Tetradecanoylphorbol Acetate