CACNA1D overexpression and voltage-gated calcium channels in prostate cancer during androgen deprivation

Abstract

Abstract Prostate cancer is often treated by perturbing androgen receptor signalling. CACNA1D , encoding Ca V 1.3 ion channels is upregulated in prostate cancer. Here we show how hormone therapy affects CACNA1D expression and Ca V 1.3 function. Human prostate cells (LNCaP, VCaP, C4-2B, normal RWPE-1) and a tissue microarray were used. Cells were treated with anti-androgen drug, Enzalutamide (ENZ) or androgen-removal from media, mimicking androgen-deprivation therapy (ADT). Proliferation assays, qPCR, Western blot, immunofluorescence, Ca 2+ -imaging and patch-clamp electrophysiology were performed. Nifedipine, Bay K 8644 (Ca V 1.3 inhibitor, activator), mibefradil, Ni 2+ (Ca V 3.2 inhibitors) and high K + depolarising solution were employed. CACNA1D and Ca V 1.3 protein are overexpressed in prostate tumours and CACNA1D was overexpressed in androgen-sensitive prostate cancer cells. In LNCaP, ADT or ENZ increased CACNA1D time-dependently whereas total protein showed little change. Untreated LNCaP were unresponsive to depolarising high K + /Bay K (to activate Ca V 1.3); moreover, currents were rarely detected. ADT or ENZ-treated LNCaP exhibited nifedipine-sensitive Ca 2+ -transients; ADT-treated LNCaP exhibited mibefradil-sensitive or, occasionally, nifedipine-sensitive inward currents. CACNA1D knockdown reduced the subpopulation of treated-LNCaP with Ca V 1.3 activity. VCaP displayed nifedipine-sensitive high K + /Bay K transients (responding subpopulation was increased by ENZ), and Ni 2+ -sensitive currents. Hormone therapy enables depolarization/Bay K-evoked Ca 2+ -transients and detection of Ca V 1.3 and Ca V 3.2 currents. Physiological and genomic CACNA1D /Ca V 1.3 mechanisms are likely active during hormone therapy—their modulation may offer therapeutic advantage.