['Our previous work demonstrated that the human placenta expresses CYP17 and is capable of de novo production of C-19 steroids; thus, it has intrinsic capacity to generate estrogens without fetal or maternal steroid precursors.', 'Our objective was to elucidate the regulation of CYP17 expression and androgen production in the human trophoblasts.', 'Fresh placentas and JEG-3 cells were used for all experiments. CYP17 mRNA analysis was performed via RT-PCR, and steroid products were quantified using RIA. To assess protein kinase A (PKA) pathway involvement, a pharmacological approach was used with forskolin (FSK) (10 μM), an activator, and H89 (10 μM), an inhibitor of the PKA pathway.', 'FSK treatment amplified CYP17 mRNA levels in both cell types when compared with basal, with levels increasing over time, peaking at 72 h, and appearing more robust in primary cells; this difference ranged from 2- to 10-fold and was statistically significant at all time points. Meanwhile, H89 reduced CYP17 levels and blunted the effect of FSK when the treatments were combined. Similarly, FSK treatment significantly increased 17α-hydroxyprogesterone concentration in both cell cultures, and H89 blunted that effect as well.'] Does the protein kinase a pathway regulate CYP17 expression and androgen production in the human placenta?