The effect of insulin and insulin-like growth factors on the expression of steroidogenic enzymes in a human ovarian thecal-like tumor cell model

Objective: To determine the effects of insulin and insulin-like growth factors (IGF-I and IGF-II) on steroidogenesis and steroidogenic enzyme expression in a human ovarian thecal-like tumor cell culture model system. Design: Human ovarian thecal-like tumor cells treated with forskolin and insulin IGF-I or IGF-II were evaluated for media accumulation of P and androstenedione (A) as well as 3β-hydroxysteroid dehydrogenase (3βHSD) and cytochrome P450 17α-hydroxylase (P450c17) enzyme activity. Northern analysis of cytochrome P450 side chain cleavage (P450scc), P450c17, and 3βHSD messenger RNA (mRNA) also was performed. Results: Basal hormone secretion, enzyme activity, and mRNA levels were not affected by treatment with insulin or the IGFs. Forskolin treatment stimulated steroid production, enzyme activity, and mRNA content. Forskolin-stimulated P secretion was augmented 30% by treatment with insulin and IGFs, whereas 3βHSD activity was augmented twofold to threefold. Forskolin stimulated A and P450c17 activity were enhanced by treatment with insulin and the [GFs. In forskolin-treated cells, P450c17 and P450scc mRNA levels were not affected by insulin (100 nM) or IGF (10 nM) treatment; however, 3βHSD mRNA levels were augmented by treatment with insulin and IGFs. Conclusions: We observed that forskolin-stimulated human ovarian thecal-like tumor cell steroidogenesis, P450c17, and 3βHSD activity, as well as mRNA content for P450scc, 3βHSD, and P450c17. Insulin and the IGFs augmented forskolin-stimulated production of P and the expression of 3βHSD, with little effect on A production, P450scc, or P450c17 expression.