title: Prooxidative effect of copper--metallothionein in the acute cytotoxicity of hydrogen peroxide in Ehrlich ascites tumour cells.
abstract: This study was concerned with the role of copper (Cu) and Cu-metallothionein (Cu-MT) in oxidative stress. Hydrogen peroxide (H(2)O(2))-induced oxidative injury was examined in Ehrlich ascites tumour cells isolated from host mice pretreated with 0, 1 or 2mg of CuSO(4) (ip) 24h earlier. Control Ehrlich cells contained low levels of Cu and Cu treatment produced dose-related increases in cellular Cu and Cu-MT levels and corresponding increases in sensitivity to oxidative toxicity of H(2)O(2) (LC(50), cell blebbing, lipid peroxidation, GSH depletion, and increase in intracellular free [Ca(2+)](i)). Hydrogen peroxide treatment also resulted in the oxidation of MT thiolates, reduction in the binding of Cu to MT resulting in translocation of Cu to other subcellular sites. d-penicillamine, a Cu-chelating agent, obliterated the sensitization effect of Cu-pretreatment and reduced the redistribution of MT-bound Cu, suggesting the participation of Cu ions derived from MT in promoting oxidant stress. Additional experiments with desferoxamine and mannitol have revealed the involvement of a Cu-dependent Fenton reaction in the mediation of the prooxidative effect of Cu-MT. These data suggest that cells with high levels of Cu-MT may be particularly susceptible to oxidative stress.
authors.affiliation: Medical Sciences Division, Northern Ontario School of Medicine, Lakehead University, 955 Oliver Road, Thunder Bay, Ont., Canada P7B 5E1. Zacharias.Suntres@NorMed.ca
authors.forename: Zacharias E
authors.initials: ZE
authors.lastname: Suntres
authors.forename: Edmund M K
authors.initials: EM
authors.lastname: Lui
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism / Q000473:pathology; D002470:Cell Survival / Q000187:drug effects; D003300:Copper / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D019327:Copper Sulfate / Q000494:pharmacology; D003676:Deferoxamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019803:Glutathione Disulfide / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000633:toxicity*; D007274:Injections, Intraperitoneal; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008353:Mannitol / Q000494:pharmacology; D008668:Metallothionein / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D018384:Oxidative Stress / Q000187:drug effects; D010396:Penicillamine / Q000494:pharmacology; D010873:Pinocytosis / Q000187:drug effects; D013997:Time Factors; D014407:Tumor Cells, Cultured; D015032:Zinc / Q000737:chemistry / Q000378:metabolism
chemical_list: D008353:Mannitol; D003300:Copper; D008668:Metallothionein; D006861:Hydrogen Peroxide; D007501:Iron; D010396:Penicillamine; D003676:Deferoxamine; D015032:Zinc; D019327:Copper Sulfate; D002118:Calcium; D019803:Glutathione Disulfide