Reactive oxygen species mediate androgen receptor- and serum starvation-elicited downstream signaling of ADAM9 expression in human prostate cancer cells

BACKGROUND: The A Disintegrin And Metalloprotease (ADAM) family is a group of transmembrane proteins containing cell adhesive and proteolytic functional domains. ADAM9 expression was shown to be mediated by androgen receptor (AR) and stress conditions. This study determined a common mediator responsible for ADAM9 protein regulation which supports human prostate cancer (PCa) cell growth and survival. METHODS: ADAM9 protein expression was measured under androgen, anti-androgen, hydrogen peroxide, and/or serum starvation conditions in PCa cells. The roles of reactive oxygen species (ROS) were assessed in the presence or absence of recombinant catalase, or in cells stably transfected with either catalase- or a control neo-cDNA expression vector. ROS was assayed by dihydroethidium (DHE) followed by FACS analysis. RESULTS: ADAM9 protein expression was upregulated by androgen in AR-positive but not in AR-negative PCa cells. The anti-androgen bicalutamide effectively blocked this induction. While serum starvation enhanced ADAM9 expression in AR-positive PCa cells, this stress condition did not alter ADAM9 expression in AR-negative PCa cells. Parallel results also showed that androgen treatment or serum starvation enhanced ROS only in AR-positive but not in AR-negative PCa cells. ROS appears to be a common downstream mediator of androgen- or serum starvation-induced ADAM9 expression since addition of hydrogen peroxide or introduction of catalase, either enhanced or abolished respectively ADAM9 protein expression by both AR-positive and -negative PCa cells.