title: Reactive oxygen species and mitochondria mediate the induction of apoptosis in human hepatoma HepG2 cells by the rodent peroxisome proliferator and hepatocarcinogen, perfluorooctanoic acid.
abstract: We have previously shown that one of the most potent rodent hepatocarcinogens, perfluorooctanoic acid (PFOA), induces apoptosis in human HepG2 cells in a dose- and time-dependent manner. In this study we have investigated the involvement of reactive oxygen species (ROS), mitochondria, and caspase-9 in PFOA-induced apoptosis. Treatment with 200 and 400 microM PFOA was found to cause a dramatic increase in the cellular content of superoxide anions and hydrogen peroxide after 3 h. Measurement of the mitochondrial transmembrane potential (Delta Psi(m)) after PFOA treatment showed a dissipation of Delta Psi(m) at 3 h. Caspase-9 activation was seen at 5 h after treatment with 200 microM PFOA. In order to evaluate the importance of these events in PFOA-induced apoptosis, cells were cotreated with PFOA and N-acetylcysteine (NAC), a precursor of glutathione, or Cyclosporin A (CsA), an inhibitor of mitochondrial permeability transition pore (MPT pore). NAC reduced Delta Psi(m) dissipation, caspase 9 activation, and apoptosis, indicating a role for PFOA-induced ROS. In addition, CsA also reduced Delta Psi(m) dissipation, caspase 9 activation, and apoptosis, indicating a role for PFOA-induced opening of the MPT pore. In summary, we have delineated a ROS and mitochondria-mediated pathway for induction of apoptosis by PFOA.
authors.affiliation: Unit of Biochemical Toxicology, Department of Biochemistry, Wallenberg Laboratory, Stockholm University, S-106 91 Stockholm, Sweden. theoharis.panaretakis@cck.ki.se
authors.forename: T
authors.initials: T
authors.lastname: Panaretakis
authors.forename: I G
authors.initials: IG
authors.lastname: Shabalina
authors.forename: D
authors.initials: D
authors.lastname: Grandér
authors.forename: M C
authors.initials: MC
authors.lastname: Shoshan
authors.forename: J W
authors.initials: JW
authors.lastname: DePierre
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002210:Caprylates / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005434:Flow Cytometry; D005466:Fluorocarbons / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007700:Kinetics; D008113:Liver Neoplasms / Q000473:pathology*; D008564:Membrane Potentials; D008930:Mitochondria, Liver / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D002210:Caprylates; D002273:Carcinogens; D005466:Fluorocarbons; D017382:Reactive Oxygen Species; D013481:Superoxides; D016572:Cyclosporine; C023036:perfluorooctanoic acid; D006861:Hydrogen Peroxide; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases; D000111:Acetylcysteine