Regulation of steroid 17αhydroxylase in adrenocortical cells in culture

The regulation of steroid 17αhydroxylase 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, 17αhydroxylase and 3βhydroxysteroid dehydrogenase (3βHSD), are under dual regulation by the cyclic AMP and protein kinase C second messenger systems; (iv) for 17αhydroxylase, this dual regulation is mediated by changes in 17αhydroxylase mRNA levels; (v) bovine adrenocortical cells can be transfected with SV40 T antigen, producing lines with elevated differentiated functions, including stabilized high expression of 17αhydroxylase; (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 17αhydroxylase regulation.