Econazole‐induced Ca2+ fluxes and apoptosis in human oral cancer cells

Abstract

AbstractThe effect of econazole on cytosolic free Ca2+ concentrations ([Ca2+]i) and viability was explored in human oral cancer cells (OC2), using the fluorescent dyes fura‐2 and WST‐1, respectively. Econazole at concentrations of >1 µM increased [Ca2+]i in a concentration‐dependent manner. The Ca2+ signal was reduced partly by removing extracellular Ca2+. The econazole‐induced Ca2+ influx was sensitive to blockade of aristolochic acid (phospholipase A2 inhibitor) and GF109203X (PKC inhibitor). In Ca2+‐free medium, after treatment with 1 µM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor), 30 µM econazole failed to induce a [Ca2+]i rise. Inhibition of phospholipase C with 2 µM U73122 substantially suppressed econazole‐induced [Ca2+]i rise. At concentrations of 5–70 µM econazole killed cells in a concentration‐dependent manner. The cytotoxic effect of 50 µM econazole was enhanced by prechelating cytosolic Ca2+ with 1,2‐bis(2‐aminophenoxy)ethane‐N,N,N′,N′‐tetraacetic acid (BAPTA). The ERK MAPK inhibitor, PD98059 (10 µM), also enhanced 20 µM econazole‐induced cell death. Propidium iodide staining data suggest that econazole induced apoptosis between concentrations of 10–70 µM. Collectively, in OC2 cells, econazole induced [Ca2+]i rises by causing Ca2+ release from the endoplasmic reticulum and Ca2+ influx from phospholipase A2/PKC‐regulated Ca2+ channels. Furthermore, econazole caused cell death appeared to be regulated by ERK MAPK. Drug Dev Res 71: 240–248, 2010. © 2010 Wiley‐Liss, Inc.