title: L-ascorbic acid (vitamin C) induces the apoptosis of B16 murine melanoma cells via a caspase-8-independent pathway.
abstract: L-ascorbic acid (vitamin C) has been reported to play a role in the treatment and prevention of cancer. However, its specific mechanistic pathways remain obscure. This study was carried out to identify the sodium ascorbate-induced apoptotic pathway in B16F10 murine melanoma cells. Sodium ascorbate was found to induce the apoptosis of B16F10 murine melanoma in a time- and dose-dependent manner, and this was prevented by pretreatment with N-acetyl- L-cysteine (NAC), a well-known antioxidant. In fact, sodium ascorbate-treated B16F10 melanoma cells showed increased intracellular reactive oxygen species generation (ROS) levels. These results indicate that sodium ascorbate induced apoptosis in B16F10 murine melanoma cells by acting as a prooxidant. We examined the involvement of caspase-8 using a specific caspase-8 inhibitor (z-IETD-fmk) on the sodium ascorbate-induced apoptotic pathway. Cell death was found not to be inhibited by z-IETD-fmk treatment, indicating that sodium ascorbate-induced apoptosis is not mediated by caspase-8. In addition, we detected a reduction in the mitochondrial membrane potential during apoptosis and confirmed cytochrome-c release from mitochondria by immunoblotting. Taken together, it appears that the induction of a prooxidant state by sodium ascorbate and a subsequent reduction in mitochondrial membrane potential are involved in the apoptotic pathway of B16F10 murine melanoma cells, and that this occurs in a caspase-8-independent manner.
authors.affiliation: Department of Anatomy and Tumor Immunity Medical Research Center, Seoul National University College of Medicine, 110-799 Seoul, South Korea.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Kang
authors.forename: Daeho
authors.initials: D
authors.lastname: Cho
authors.forename: Young-In
authors.initials: YI
authors.lastname: Kim
authors.forename: Eunsil
authors.initials: E
authors.lastname: Hahm
authors.forename: Yoolhee
authors.initials: Y
authors.lastname: Yang
authors.forename: Daejin
authors.initials: D
authors.lastname: Kim
authors.forename: Daeyoung
authors.initials: D
authors.lastname: Hur
authors.forename: Hyunjeong
authors.initials: H
authors.lastname: Park
authors.forename: Saic
authors.initials: S
authors.lastname: Bang
authors.forename: Young Il
authors.initials: YI
authors.lastname: Hwang
authors.forename: Wang Jae
authors.initials: WJ
authors.lastname: Lee
mesh_terms: D000818:Animals; D017209:Apoptosis; D001205:Ascorbic Acid / Q000494:pharmacology*; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D008546:Melanoma, Experimental / Q000473:pathology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008928:Mitochondria / Q000187:drug effects; D016877:Oxidants / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D016877:Oxidants; D017382:Reactive Oxygen Species; D045304:Cytochromes c; C505526:Casp8 protein, mouse; C506434:Casp9 protein, mouse; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D001205:Ascorbic Acid