Role of reactive oxygen species in apoptosis induced by N-ethylmaleimide in HepG2 human hepatoblastoma cells

Abstract

We have previously reported that N-ethylmaleimide induces apoptosis through activation of K +, Cl −-cotransport in HepG2 human hepatoblastoma cells. In this study, we investigated the role for reactive oxygen species as a mediator of the apoptosis induced by N-ethylmaleimide. N-ethylmaleimide induced a significant elevation of intracellular level of reactive oxygen species. Treatment with antioxidants ( N-acetyl cysteine, N, N′-diphenyl- p-phenylenediamine) which markedly suppressed generation of reactive oxygen species, significantly inhibited the N-ethylmaleimide-induced activation of K +, Cl −-cotransport and apoptosis. Inhibitors of NADPH oxidase (diphenylene iodonium, apocynin, d-(+)-neopterine) also significantly blunted the generation of reactive oxygen species, activation of K +, Cl −-cotransport and apoptosis induced by N-ethylmaleimide. These results suggest that reactive oxygen species generated through activation of NADPH oxidase may play a role in the N-ethylmaleimide-induced stimulation of K +, Cl −-cotransport and apoptosis in HepG2 cells.