Ca²⁺ Movement Induced by Deltamethrin in PC3 Human Prostate Cancer Cells

This study explored the effect of deltamethrin, a pesticide, on intracellular free Ca²⁺ concentration ([Ca²⁺]i) in PC3 human prostate cancer cells. Deltamethrin at concentrations between 5 μM and 20 μM evoked [Ca²⁺]i rises in a concentration-dependent manner. This Ca²⁺ signal was inhibited by 22% by removal of extracellular Ca²⁺. Nifedipine, econazole, and SKF96365 also inhibited the Ca²⁺ signal. Treatment with the endoplasmic reticulum Ca²⁺ pump inhibitor 2,5-di-tert-butylhydroquinone (BHQ) in Ca²⁺-free medium nearly abolished deltamethrin-induced [Ca²⁺]i rises. Treatment with deltamethrin also inhibited most of BHQ-induced [Ca²⁺]i rises. Inhibition of phospholipase C (PLC) with U73122 failed to alter deltamethrin-evoked [Ca²⁺]i rises. Deltamethrin killed cells at concentrations of 20-100 μM in a concentration-dependent fashion. Chelation of cytosolic Ca²⁺ with 1,2-bis (2-aminophenoxy) ethane-N, N, N', N'-tetraacetic acid/acetoxymethyl ester (BAPTA/AM) did not prevent deltamethrin's cytotoxicity. Together, in PC3 human prostate cancer cells, deltamethrin induced [Ca²⁺]i rises that involved Ca²⁺ entry through store-operated Ca²⁺ channels and PLC-independent Ca²⁺ release from the endoplasmic reticulum. Deltamethrin induced cytotoxicity in a Ca²⁺-independent manner.