Steroid regulation of progesterone synthesis in a stable porcine granulosacell line: a role for progestins

The objective of this investigation was to determine the effect of steroid hormones on the synthesis of progesterone in a stable porcine granulosa cel l line, JC-410. We also examined the effect of steroid hormones on expressi on of the genes encoding the steroidogenic enzymes, cytochrome P450-cholest erol side chain cleavage (P450scc) and 3 beta-hydroxy-5-ene steroid dehydro genase (3 beta-HSD). We observed that 48 h exposure of the JC-410 cells to estradiol-17 beta (estradiol), androstenedione, 5 alpha-dihydrotestosterone , levonorgestrel, and 5-cholesten-3 beta, 25-diol (25-hydroxycholesterol) r esulted in stimulation of progesterone synthesis. 25-Hydroxycholesterol aug mented progesterone synthesis stimulated by estradiol, 5 alpha-dihydrotesto sterone, levonorgestrel and 8-bromoadenosine 3':5'-cyclic monophosphate (8- Br-cAMP). This increase in progesterone synthesis was additive with estradi ol Sa-dihydrotestosterone and levonorgestrel, and synergistic with 8-Br-cAM P. Cholera toxin? progesterone, levonorgestrel and androstenedione increase d P450sce mRNA levels, whereas estradiol had no effect. Cholera toxin, prog esterone and levonorgestrel increased 3 beta-HSD mRNA levels, but estradiol and androstenedione had no effect. The results were interpreted to mean th at estrogens, androgens and progestins regulate progesterone synthesis in t he JC-410 cells. The effect of androgens appears to be mediated by stimulat ion of P450scc gene expression while progestins stimulate both P450scc and 38-HSD gene expression. Our results support the concept that progesterone i s an autocrine regulator of its own synthesis in granulosa cells. (C) 1999 Elsevier Science Ltd. All rights reserved.