Speaker
Description
Prostate cancer remains one of the most diagnosed cancers in men. Surgical interventions and radiation therapy are typically employed for early-stage disease, while androgen deprivation therapy (ADT) is used for metastatic cases. However, relapses and treatment resistance often occur over time. A key factor in this resistance is the overproduction of androgens, driven by activation of CYP17A1-17,20 lyase activity, a critical step in androgen biosynthesis. CYP17A1 is a crucial enzyme in androgen production, exhibiting both hydroxylase and lyase activities. The post-translational modification of CYP17A1, potentially by specific protein kinases or phosphatases, is thought to play a significant role in regulating these activities. Our work identified several kinases and phosphatases, including MAPK14, PPP2CA, DUSP6, and others, as potential regulators of CYP17A1-17,20 lyase activity. In this study, we examined the functional role of these proteins by evaluating their effects on CYP17A1 activity. CYP17A1 and kinases or phosphatases were co-expressed in COS-1 cells, and enzymatic activity was assessed using 14C-labeled progesterone and tritiated 17-OH-pregnenolone to measure hydroxylase and lyase activities. To further validate these regulatory interactions, pharmacological inhibitors of the identified kinases and phosphatases were used to treat adrenal H295R cells, and the enzyme activity was measured 4 hours after treatment. Our in vivo and in vitro results demonstrate that MAPK14, PPP2CA, and DUSP6 significantly regulate CYP17A1-17,20 lyase activity without affecting the hydroxylase activity. Inhibitor studies further support the direct regulatory roles of MAPK14, DUSP6, and PPP2CA in CYP17A1 activity. Notably, higher concentrations of the MAPK14 inhibitor markedly reduced lyase activity, with a slight impact on hydroxylase function; the DUSP6 inhibitor significantly increased lyase activity at lower concentrations but exerted negative feedback at higher concentrations, while the PPP2CA inhibitor increased lyase activity at higher concentrations with no effects on hydroxylase activity. Our findings highlight the selective regulation of CYP17A1 lyase activity and suggest that phosphorylation-dependent regulation of CYP17A1 may represent a promising therapeutic target to limit androgen production and overcome treatment resistance in prostate cancer.