title: Mitochondrial O2*- and H2O2 mediate glucose deprivation-induced stress in human cancer cells.
abstract: The hypothesis that glucose deprivation-induced cytotoxicity in transformed human cells is mediated by mitochondrial O2*- and H2O2 was first tested by exposing glucose-deprived SV40-transformed human fibroblasts (GM00637G) to electron transport chain blockers (ETCBs) known to increase mitochondrial O2*- and H2O2 production (antimycin A (AntA), myxothiazol (Myx), or rotenone (Rot)). Glucose deprivation (2-8 h) in the presence of ETCBs enhanced parameters indicative of oxidative stress (i.e. GSSG and steady-state levels of oxygen-centered radicals) as well as cytotoxicity. Glucose deprivation in the presence of AntA also significantly enhanced cytotoxicity and parameters indicative of oxidative stress in several different human cancer cell lines (PC-3, DU145, MDA-MB231, and HT-29). In addition, human osteosarcoma cells lacking functional mitochondrial electron transport chains (rho0) were resistant to glucose deprivation-induced cytotoxicity and oxidative stress in the presence of AntA. In the absence of ETCBs, aminotriazole-mediated inactivation of catalase in PC-3 cells demonstrated increases in intracellular steady-state levels of H2O2 during glucose deprivation. Finally, in the absence of ETCBs, overexpression of manganese containing superoxide dismutase and/or mitochondrial targeted catalase using adenoviral vectors significantly protected PC-3 cells from toxicity and oxidative stress induced by glucose deprivation with expression of both enzymes providing greater protection than was seen with either alone. Overall, these findings strongly support the hypothesis that mitochondrial O2*- and H2O2 significantly contribute to glucose deprivation-induced cytotoxicity and metabolic oxidative stress in human cancer cells.
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: Iman M
authors.initials: IM
authors.lastname: Ahmad
authors.forename: Nukhet
authors.initials: N
authors.lastname: Aykin-Burns
authors.forename: Julia E
authors.initials: JE
authors.lastname: Sim
authors.forename: Susan A
authors.initials: SA
authors.lastname: Walsh
authors.forename: Ryuji
authors.initials: R
authors.lastname: Higashikubo
authors.forename: Garry R
authors.initials: GR
authors.lastname: Buettner
authors.forename: Sujatha
authors.initials: S
authors.lastname: Venkataraman
authors.forename: Michael A
authors.initials: MA
authors.lastname: Mackey
authors.forename: Shawn W
authors.initials: SW
authors.lastname: Flanagan
authors.forename: Larry W
authors.initials: LW
authors.lastname: Oberley
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Spitz
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D000968:Antimycin A / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D015153:Blotting, Western; D002374:Catalase / Q000378:metabolism; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002470:Cell Survival; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D004583:Electrons; D005347:Fibroblasts / Q000378:metabolism; D005609:Free Radicals; D005947:Glucose / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology*; D008345:Manganese / Q000494:pharmacology; D008689:Methacrylates; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D009249:NADP / Q000737:chemistry / Q000378:metabolism; D012516:Osteosarcoma / Q000378:metabolism; D016877:Oxidants / Q000737:chemistry; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D008689:Methacrylates; D016877:Oxidants; D013844:Thiazoles; D012402:Rotenone; D008345:Manganese; D009249:NADP; D000968:Antimycin A; C030517:myxothiazol; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005978:Glutathione; D005947:Glucose; D010100:Oxygen