Inhibition of store-operated Ca(2+) channels prevent ethanol-induced intracellular Ca(2+) increase and cell injury in a human hepatoma cell line

Abstract

Elevated intracellular Ca(2+) content is implicated in ethanol-induced hepatocyte apoptosis and necrosis. Extracellular Ca(2+) influx has been suggested to play a role in this process. However, the exact Ca(2+)-permeable channel involved in the plasma membrane is still unclear. This study investigated the role of store-operated calcium entry (SOCE) in ethanol-induced cytosolic free Ca(2+) concentrations ([Ca(2+)](i)) increase and hepatotoxicity. Ethanol (25-800mM) dose-dependently increased [Ca(2+)](i) content and hepatocyte damage in HepG2 cells. 2-aminoethoxydiphenyl borate (2-APB), the proved efficient antagonist of SOCs, dose-dependently suppressed the ethanol (200nM)-increased [Ca(2+)](i) content and protected against ethanol-induced viability loss and transaminase leakage. Exposure to 200mM ethanol for 24h significantly upregulated the mRNA and protein expression of calcium release-activated calcium channel protein 1 (CRACM1, Orai1) and stromal interaction molecule 1 (STIM1), the two main molecular constituents of SOCs, which was sustained for at least 72h. In addition, small interfering RNA knockdown of STIM1 attenuated the ethanol-increased [Ca(2+)](i) content and hepatotoxicity. Taken together, these data indicate that the Ca(2+) channel of SOCE may be involved in the pathogenesis of ethanol-induced intracellular Ca(2+) elevation and consequent hepatocyte damage.