The effects of growth factors and phorbol esters on steroid biosynthesis in isolated human theca interna and granulosa-lutein cells in long term culture.

Abstract

In this report we examined the effects of growth factors and phorbol esters on steroid hydroxylase activity in cultured human thecal and granulosa-lutein cells. Treatment of thecal cells with epidermal growth factor (EGF), fibroblast growth factor (FGF), transforming growth factor-beta (TGF beta), and tetradecanoyl phorbol acetate (TPA) resulted in the inhibition of forskolin- and dibutyryl cAMP-stimulated 17 alpha-hydroxylase activity and 17 alpha-hydroxyprogesterone and dehydroepiandrosterone production. In contrast, cAMP-stimulated 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) activity was enhanced by FGF and TGF beta, and treatment with EGF enhanced cAMP-stimulated progesterone production. cAMP stimulated 3 beta HSD activity was unaffected by TPA (10 nmol/L) treatment, yet TPA inhibited cAMP-stimulated progesterone production. Basal 3 beta HSD activity and progesterone production were inhibited by TPA. In contrast to the inhibitory actions of EGF, FGF, and TGF beta on 17 alpha-hydroxylase expression, insulin and insulin-like growth factor-I enhanced forskolin-stimulated 17 alpha-hydroxylase activity. In granulosa-lutein cells, forskolin-stimulated aromatase activity was suppressed by EGF, FGF, and TPA. TGF beta had no effect on forskolin-stimulated aromatase activity. EGF, FGF, and TGF beta did not affect forskolin-stimulated progesterone production, whereas treatment with TPA inhibited cAMP-stimulated progesterone secretion. These data suggest that growth factors may differentially regulate cAMP-dependent processes in human thecal and granulosa cells of the developing follicle.