Cytochrome P450 17A1 (CYP17A1) and intracrine androgen synthesis enzymes (CYP17A1 and related enzymes)

Cytochrome P450 17A1 (CYP17A1) is a key bifunctional enzyme in the steroidogenic pathway, localized in the endoplasmic reticulum, that catalyzes both 17-alpha-hydroxylase and 17,20-lyase reactions (UniProt: P05093). It is essential for the production of glucocorticoids and androgens in the adrenal glands and gonads, serving as a gatekeeper for the synthesis of testosterone and dihydrotestosterone (DHT). In advanced prostate cancer, particularly castration-resistant prostate cancer (CRPC), tumor cells often develop the capacity for intracrine androgen synthesis, utilizing enzymes like CYP17A1, 3-beta-hydroxysteroid dehydrogenase (HSD3B), and 5-alpha-reductase (SRD5A) to produce potent androgens locally from cholesterol or adrenal precursors (PubMed: 24618710). Targeting this pathway with inhibitors such as abiraterone acetate effectively lowers systemic and intra-tumoral androgen levels, thereby slowing disease progression (PubMed: 22533354). However, because CYP17A1 inhibition also blocks cortisol synthesis, it leads to a compensatory rise in adrenocorticotropic hormone (ACTH), which can cause mineralocorticoid excess (hypertension, hypokalemia) unless managed with exogenous corticosteroids (NIH: StatPearls). This target group represents a critical node in the management of hormone-dependent malignancies and endocrine disorders.

Other names

Steroid 17-alpha-hydroxylase/17,20 lyaseCYP17P450c1717-alpha-monooxygenaseIntracrine androgenic pathway enzymes

Inhibition of the dual 17-alpha-hydroxylase and 17,20-lyase activities of the CYP17A1 enzyme, which prevents the conversion of C21 steroids to C19 androgen precursors, alongside the inhibition of other intracrine enzymes like 5-alpha-reductase to block the conversion of testosterone to dihydrotestosterone (PubMed: 22533354, PubMed: 24618710).