Finasteride Blocks Progesterone Synthesis in MA-10 Leydig Tumor Cells

The study found that finasteride inhibits progesterone synthesis in MA-10 Leydig tumor cells, but not in human granulosa cells or rat Leydig tumor cells. The inhibition is dose-dependent and occurs at a concentration significantly less than serum concentrations detected in finasteride-treated patients. Finasteride blocks cholesterol side-chain cleavage, which can inhibit steroidogenesis. The effect of finasteride to block cholesterol side-chain cleavage may be species-specific. The study suggests that finasteride may have unique research applications as a probe for the mouse side-chain cleavage enzyme, but also highlights the potential problem of designing 5a-reductase inhibitors that may inhibit more than the expected target enzyme and cause undesired side-effects.