Role of NAD(P)H oxidase in the tamoxifen-induced generation of reactive oxygen species and apoptosis in HepG2 human hepatoblastoma cells.
Previously, tamoxifen (TAM) has been shown to induce apoptosis through elevation of intracellular Ca2+ in HepG2 human hepatoblastoma cells. In this study we investigated the role of reactive oxygen species (ROS) in the TAM-induced apoptosis, and interrelationship between intracellular Ca2+ and ROS. TAM induced a slow and sustained increase in intracellular ROS level. An antioxidant, N-acetylcysteine significantly inhibited both ROS production and apoptosis induced by TAM, suggesting that ROS may play an essential role in the TAM-induced apoptosis. In a time frame ROS generation followed intracellular Ca2+ increase, and the extracellular and intracellular Ca2+ chelation with EGTA and BAPTA/AM, respectively, completely inhibited the TAM-induced ROS production, indicating that intracellular Ca2+ may mediate the ROS generation. Inhibitors of NAD(P)H oxidase, diphenylene iodonium, phenylarsine oxide and neopterine, significantly blocked the TAM-induced ROS generation and apoptosis, implying that this oxidase may act as a source enzyme for the production of ROS. These results suggest that non-phagocytic NAD(P)H oxidase may play a novel role as a mediator of the apoptosis associated with intracellular Ca2+ in HepG2 cells.
Lee
Y S
YS
Department of Physiology, College of Medicine, Kwandong University, Kangnung 210-701, Korea.
Kang
Y S
YS
Lee
S H
SH
Kim
J A
JA
D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D018197:Hepatoblastoma; D006801:Humans; D008113:Liver Neoplasms; D019255:NADPH Oxidases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013629:Tamoxifen / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000201:enzymology
D018931:Antineoplastic Agents, Hormonal; D017382:Reactive Oxygen Species; D013629:Tamoxifen; D019255:NADPH Oxidases; D002118:Calcium