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 (25–800 mM) 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 (200 nM)-increased [Ca 2+] i content and protected against ethanol-induced viability loss and transaminase leakage. Exposure to 200 mM ethanol for 24 h 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 72 h. 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.