The action of phorbol ester on steroidogenesis in cultured human fetal adrenal cells.
The potent mitogen and tumor promoter, phorbol 12-myristate 13-acetate (PMA), has a primary action via activation of calcium-dependent protein kinase C. The treatment of monolayer cultures of human fetal adrenal neocortex (HFA) cells with PMA (50-250 nM) stimulated basal dehydroepiandrosterone sulfate (DS) secretion 2-3 fold. ACTH-treated HFA cells secreted amounts of DS and cortisol (F) 10-50 fold greater than basal secretions. PMA (250 nM) addition with ACTH to HFA cells decreased DS and F secretions at least 75% on days 2 and 3 of treatment. Treatment of HFA cells with 4 alpha-phorbol, which does not activate calcium-dependent protein kinase C, did not inhibit steroidogenesis. The attenuated rates of steroidogenesis after PMA treatment correlated with the decreased amounts of steroid 11 beta, 17 alpha- and 21-hydroxylase cholesterol side-chain cleavage steroid dehydrogenase and sulfotransferase activities. The decrease of steroid 17 alpha-hydroxylase activity correlated with the decreased amount of cytochrome P-450(17) alpha as determined after protein immunoblotting of NaDodSO4 cell lysates. After PMA treatment the ACTH-promoted increases of hydroxysteroid sulfotransferase and dehydrogenase activities of HFA cells were suppressed. PMA (50 nM) inhibited cAMP accumulation in ACTH-treated HFA cells, while 4 alpha-phorbol had no effect. Importantly, dibutyryl cAMP (0.2 mM) treatment of HFA cells did not reverse phorbol ester-promoted attenuation of steroidogenesis. We conclude that, in the presence of ACTH, phorbol ester chronically inhibits both cAMP synthesis and cAMP-dependent protein kinase action with resultant decreased steroidogenic enzyme synthesis and steroid production. This may be a consequence of activation, migration and a slow degradation of protein kinase C activity. These multifaceted actions of phorbol ester and associated protein kinase C activation may have critical effects on the ontogeny of fetal adrenal function.
D000302:Adrenal Cortex / Q000196:embryology*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives / Q000378:metabolism; D019314:Dehydroepiandrosterone Sulfate; D004075:Diglycerides / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D010703:Phorbol Esters / Q000494:pharmacology*; D010704:Phorbols / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004075:Diglycerides; D010703:Phorbol Esters; D010704:Phorbols; D003687:Dehydroepiandrosterone; D019314:Dehydroepiandrosterone Sulfate; D003994:Bucladesine; D000324:Adrenocorticotropic Hormone; D000242:Cyclic AMP; D013250:Steroid Hydroxylases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D006854:Hydrocortisone; C033085:phorbol