Phorbol ester-induced contractility and Ca 2+ influx in human cultured prostatic stromal cells

Abstract

In this study, we investigated the effects of protein kinase C (PKC)-activating phorbol esters upon Ca 2+ influx and contractility in human cultured prostatic stromal cells. Tissue obtained from patients undergoing transurethral resection of the prostate was used to generate explant cultures of prostatic stromal cells. These cells expressed detectable levels of PKCα, δ, γ, λ, and ζ, but not ϵ, ι, μ, or θ isoforms and responded to both phorbol 12,13-diacetate (PDA) and 12-deoxyphorbol 13-tetradecanoate (DPT) with concentration-dependent contractions ( p ec 50± SEM 7.07±0.41 and 6.39±0.27, respectively). The L-type Ca 2+ channel blocker nifedipine (3 μM), and the PKC inhibitors Gö 6976, Gö 6983 (both 100 nM), myristoylated PKC inhibitor 19–27 (20 μM) and bisindolylmaleimide (1 μM) all abolished PDA-stimulated (1 μM) contractions. Neither PDA nor DPT (at 1 μM) caused translocation of any PKC isoform from the cytosolic to the particulate fraction. Nifedipine (3 μM), myristoylated PKC inhibitor 19–27 (20 μM), and bisindolylmaleimide (1 μM) inhibited PDA-stimulated Ca 2+ influx into FURA-2 loaded cells. This study indicates that human cultured prostatic stromal cells respond to phorbol esters with contractions that are dependent upon the influx of Ca 2+ through L-type Ca 2+ channels and that this effect may be independent of the translocation of PKC from cytosolic to particulate fractions.