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 [Ca ²⁺]i in MDCK cells using the Ca²⁺-sensitive fluorescent dye fura-2. PEITC at 200-700 μM 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 Ca ²⁺ 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 μM, 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 μM PEITC induced apoptosis. At 10 and 15 μM, 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/Ca ²⁺-independent manner.