title: Mitochondrial transmembrane potential and reactive oxygen species generation regulate the enhanced effect of CCCP on TRAIL-induced SNU-638 cell apoptosis.
abstract: TRAIL is a member of the tumor necrosis factor family and engages apoptosis via recruitment and rapid activation of caspase-8. This study investigated the effect of carbonyl cyanide m-chlorophenylhydrazone (CCCP), a classic uncoupler of oxidative phosphorylation, on TRAIL-induced apoptosis in SNU-638 cells derived from human gastric cancer cells. It was found that treatment with CCCP followed by incubation with TRAIL markedly enhanced apoptosis by 2 fold compared with treatment with TRAIL alone. This effect was accompanied by reduction in mitochondrial transmembrane potential and generation of reactive oxygen species. This sensitization was inhibited by N-acetyl-l-cysteine, which restored the mitochondrial transmembrane potential and reduced reactive oxygen species generation. Treatment with N-acetyl-L-cysteine also inhibited expression of apoptotic proteins such as Bax and Smac and abrogated caspase-8 activation. Moreover, treatment with N-acetyl-L-cysteine prior to induction with TRAIL increased expression of the anti-apoptotic Bcl-2 protein. These data indicate that CCCP enhanced TRAIL-induced apoptosis by dissipation of mitochondrial transmembrane potential and reactive oxygen species, suggesting that treatment with CCCP combined with that with TRAIL can be an efficient method to induce death of tumor cells, particularly cells that are resistant to TRAIL-induced apoptosis.
authors.affiliation: Center for Healthcare Technology Development, College of Veterinary Medicine, Bio-Safety Research Institute, Chonbuk National University, Jeonbuk, South Korea.
authors.forename: Atul A
authors.initials: AA
authors.lastname: Chaudhari
authors.forename: Jae-Won
authors.initials: JW
authors.lastname: Seol
authors.forename: Seog-Jin
authors.initials: SJ
authors.lastname: Kang
authors.forename: Sang-Youel
authors.initials: SY
authors.lastname: Park
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000378:metabolism*; D045744:Cell Line, Tumor; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000111:Acetylcysteine