Role of Ca2+-activated Cl- channels in the mechanism of apoptosis induced by cyclosporin A in a human hepatoma cell line.
The mechanism of apoptosis induced by cyclosporin A (CsA) in a human hepatoma cell line was investigated. CsA induced apoptosis in a dose- and time-dependent manner in HepG2 human hepatoma cells. CsA induced Cl- efflux, which was significantly blocked by niflumic acid (NA), a specific inhibitor, and flufenamic acid (FA), 5-nitro-2-(3-phenyl-propylamino)-benzoate (NPPB), and 4,4'-diisothiocyanoto-stibene-2,2'-disulfonic acid (DIDS), non-specific inhibitors of Ca2+-activated Cl- channels (CaCCs), not by calyculin A, an inhibitor of K+,Cl- -cotransport. In addition, CsA did not alter intracellular K+ concentration. Moreover, CsA increased intracellular Ca2+ concentration, and treatment with BAPTA/AM, an intracellular Ca2+ chelator, significantly inhibited the CsA-induced Cl- efflux, indicating that CsA induced Cl- efflux through the activation of CaCCs. Treatment with these CaCC inhibitors (NA, FA, NPPB, and DIDS) markedly prevented the CsA-induced apoptosis. Taken together, these results suggest that CaCCs may mediate apoptosis induced by CsA in HepG2 cells. Furthermore, these results provide a new insight into the novel function of CaCCs in the regulation of cancer cell apoptosis associated with perturbation of intracellular Ca2+ signal.
Kim
Jung-Ae
JA
College of Pharmacy, Yeungnam University, Gyongsan 712-749, South Korea.
Kang
Young Shin
YS
Lee
Yong Soo
YS
D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D002452:Cell Count; D018118:Chloride Channels / Q000187:drug effects* / Q000378:metabolism*; D002713:Chlorine / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D018197:Hepatoblastoma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology
D018118:Chloride Channels; D002713:Chlorine; D016572:Cyclosporine; D002118:Calcium