Mechanism of estrogens-induced increases in intracellular Ca(2+) in PC3 human prostate cancer cells

Abstract

Background: The effect of estrogens (diethylstilbestrol [DES], 17 beta-estradiol) on intracellular Ca(2+) concentrations ([Ca(2+)](i)) in hormone-insensitive PC3 human prostate cancer cells was examined.

Methods: [Ca(2+)](i) changes in suspended cells were measured by using the Ca(2+)-sensitive fluorescent dye fura-2.

Results: Estrogens (1--20 microM) increased [Ca(2+)](i) concentration-dependently with DES being more potent. Ca(2+) removal inhibited 50 +/- 10% of the signal. In Ca(2+)-free medium, pretreatment with 20 microM estrogens abolished the [Ca(2+)](i) increases induced by 2 microM carbonylcyanide m-chlorophenylhydrazone (CCCP, a mitochondrial uncoupler) and 1 microM thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor), but pretreatment with CCCP and thapsigargin did not alter DES-induced Ca(2+) release and partly inhibited 17 beta-estradiol-induced Ca(2+) release. Addition of 3 mM Ca(2+) increased [Ca(2+)](i) in cells pretreated with 1- 20 microM estrogens in Ca(2+)-free medium. Pretreatment with 1 microM U73122 to block phospholipase C-coupled inositol 1,4,5-trisphosphate formation did not alter estrogens-induced Ca(2+) release. The effect of 20 microM estrogen on [Ca(2+)](i) was not affected by pretreatment with 0.1 microM estrogens.

Conclusions: Estrogen induced significant Ca(2+) release and Ca(2+) influx in an inositol 1,4,5-trisphosphate-independent manner in PC3 cells. These effects of estrogens on Ca(2+) signaling appear to be nongenomic. Prostate 47:141-148, 2001.