Effect of phenethyl isothiocyanate on Ca2+ movement and viability in MDCK canine renal tubular cells

The effect of the natural compound phenethyl isothiocyanate (PEITC) on cytosolic Ca2+ concentrations ([Ca2+](i)) and viability in MDCK renal cells is unknown. This study explored whether PEITC changed [Ca2+](i) in MDCK cells using the Ca2+-sensitive fluorescent dye fura-2. PEITC at 200-700 mu M increased [Ca2+](i) in a concentration-dependent manner. The signal was reduced by removing extracellular Ca2+. PEITC-induced Ca2+ influx was inhibited by nifedipine, econazole, SK&F 96365 and protein kinase C modulators. In Ca2+-free medium, treatment with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin (TG) or 2,5-di-tert-butylhydroquinone (BHQ) inhibited PEITC-induced rise in [Ca2+](i). Incubation with PEITC also inhibited TG or BHQ-induced rise in [Ca2+](i). Inhibition of phospholipase C with U73122 abolished PEITC-induced rise in [Ca2+](i). At 15-75 mu M, PEITC decreased viability. The cytotoxic effect of PEITC was enhanced by chelating cytosolic Ca2+ with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/acetoxymethyl ester. Annexin V-FITC data suggest that 20 and 50 mu M PEITC induced apoptosis. At 10 and 15 mu M, PEITC did not increase reactive oxygen species (ROS) production. Together, in renal tubular cells, PEITC-induced rise in [Ca2+](i) by inducing phospholipase C-dependent Ca2+ release from endoplasmic reticulum and Ca2+ entry via store-operated Ca2+ channels. PEITC induced apoptosis in a concentration-dependent, ROS/Ca2+-independent manner.