A novel androgen signalling pathway uses dihydrotestosterone, but not testosterone, to activate the EGF receptor signalling cascade in prostate stromal cells

Background and Purpose Human prostate growth and function are tightly controlled by androgens that are generally thought to exert their effects by regulating gene transcription. However, a rapid, non-genomic steroid action, often involving an elevation of intracellular calcium ([Ca2+] i), has also been described in a number of cell types. In this study we investigate whether androgens acutely regulate [Ca2+]i in stromal cells derived from the human prostate. Experimental Approach Human-cultured prostatic stromal cells (HCPSCs) were loaded with the calcium-sensitive fluorophore, fura-2-acetoxymethyl ester (FURA-2AM) (10 ?M). Changes in [Ca2+]i in response to the androgens, dihydrotestosterone (DHT) and testosterone, as well as EGF were measured by fluorescence microscopy. Key Results DHT, but not testosterone (0.03-300 nM), elicited concentration-dependent elevations of [Ca2+]i within 1 min of addition. These responses were blocked by the androgen receptor antagonist, flutamide (10 ?M); the sarcoplasmic reticulum ATPase pump inhibitor, thapsigargin (1 ?M); the inositol trisphosphate receptor inhibitor, 2-aminoethyldiphenyl borate (50 ?M) and the PLC inhibitor, U-73122 (1 ?M). Responses were also blocked by the L-type calcium channel blocker, nifedipine (1 ?M), and by removal of extracellular calcium. A similar transient elevation of [Ca2+]i was elicited by EGF (100 ng?mL-1). The EGF receptor inhibitor, AG 1478 (30 nM), and the MMP inhibitor, marimastat (100 nM), blocked the DHT-induced elevation of [Ca2+]i. Conclusions and Implications These studies show that DHT elicits an androgen receptor-dependent acute elevation of [Ca 2+]i in HCPSC, most likely by activating EGF receptor signalling.