Regulation of steroid 17 alpha-hydroxylase in adrenocortical cells in culture.

The regulation of steroid 17 alpha-hydroxylase in human and bovine adrenocortical cells in culture is reviewed. It is shown that (i) the long-term growth and cloning of normal human fetal adrenocortical cells in culture is feasible; (ii) the phorbol ester 12-O-tetradecanoyl phorbol 13-acetate (TPA) is an effective mitogen in both clonal cultures and non-clonal early cultures of human adrenocortical cells, and shows a selective action in promoting adrenocortical cell growth and inhibiting fibroblast growth; (iii) the key steroidogenic enzymes, 17 alpha-hydroxylase and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), are under dual regulation by the cyclic AMP and protein kinase C second messenger systems; (iv) for 17 alpha-hydroxylase, this dual regulation is mediated by changes in 17 alpha-hydroxylase mRNA levels; (v) bovine adrenocortical cells can be transfected with SV40 T antigen, producing lines with elevated differentiated functions, including stabilized high expression of 17 alpha-hydroxylase; (vi) human adrenocortical cells can also be transfected with SV40 large T antigen, giving rise to functional cell lines which may be useful in future studies of 17 alpha-hydroxylase regulation.