Androgens regulate adenylate cyclase activity and intracellular calcium in stromal cells derived from human prostate

Increased smooth muscle tone is a significant component of benign prostatic hyperplasia, the onset of which correlates with age and declining serum testosterone levels. This study investigates the effects of androgens on key regulators of smooth muscle tone: intracellular calcium ([Ca(2+)](i)) and cyclic adenosine monophosphate (cAMP) in human cultured prostatic stromal cells (HCPSC).

HCPSC were cultured in the absence or presence of dihydrotestosterone (DHT; 3, 30, and 300 nM) or testosterone (0.3-300 nM) alone or in the presence of flutamide (10 microM). Changes in [Ca(2+)](i) were determined in FURA-2AM (10 microM) loaded cells. Changes in cAMP were determined by Alpha Screen(R) assay.

Up to 32% of cultured cells exhibited spontaneous elevations of [Ca(2+)](i). The frequency of these elevations was reduced by nifedipine (10 microM), ryanodine (1 microM), and the adenylate cyclase inhibitor MDL 12,330A (20 microM). Compared to steroid-free cells, a 3-day incubation of cells with testosterone (only 3 nM) elevated basal, but not peak [Ca(2+)](i). In the presence of flutamide, all concentrations of testosterone tested elevated basal, but not peak [Ca(2+)](i). DHT (30 and 300, but not 3 nM) lowered peak and basal [Ca(2+)](i). Increased testosterone concentration dependently decreased resting cell cAMP (pIC(50): 7.64 +/- 0.29 nM).

These findings demonstrate that some HCPSC have the ability to spontaneously and transiently elevate [Ca(2+)](i). The magnitude of these [Ca(2+)](i) peaks, along with resting levels of calcium and cAMP, appear to be regulated by androgens.