title: Cytotoxicity and the induction of the stress protein Hsp 70 in Chang liver cells in response to zearalenone-induced oxidative stress.
abstract: Zearalenone (ZEN) has been implicated in several cases of mycotoxicosis in farm animals and humans. The toxic effects of ZEN have been well characterized, but little is known regarding the mechanisms of ZEN toxicity, including the involvement of the oxidative stress pathway. Using Chang liver cells as a model, the aim of this study was to determine if ZEN could elevate the expression of the heat shock protein Hsp 70, induce cytotoxicity and modulate the levels of glutathione (GSH) and thiobarbituric acid reactive substance (TBARS). In addition, the cytoprotective effects of N-acetylcysteine amide (NACA) pre-treatment were assessed. Finally, the involvement of oxidative stress in ZEN-induced toxicity was confirmed. The results of this study demonstrated that ZEN-induced Hsp 70 expression in a dose- and time-dependent manners. This effect occurred at low-ZEN concentrations, and could therefore be considered a biomarker of ZEN-induced toxicity. The cytotoxicity was reduced when Chang liver cells were exposed to sub-lethal heat shock prior to ZEN treatment, demonstrating a cytoprotective effect of Hsp 70. This cytoprotective effect suggested that Hsp 70 might play a key role in the cellular defense mechanism. When cells were pre-treated with NACA prior to ZEN treatment, the cells were also protected from toxicity. This NACA cytoprotective effect suggested the involvement of oxidative stress in ZEN-induced toxicity, and this mechanism was supported by reduced Hsp 70 expression, inhibited cytolethality, increased GSH levels and decreased TBARS formation when cells were pre-treated with NACA prior to ZEN exposure. Our data clearly demonstrated that ZEN induced cytotoxicity in Chang liver cells by inhibiting cell proliferation, decreasing GSH levels and increasing TBARS formation in a dose-dependent manner. ZEN also, induced Hsp 70 expression, and the side effects of ZEN were significantly alleviated by pre-treatment with NACA. Oxidative stress is likely to be one of the primary pathways of ZEN toxicity. This oxidative stress may contribute, at least in part, to the mechanism of ZEN-induced cytotoxicity.
authors.affiliation: Department of Pharmacology & Toxicology, College of Veterinary Medicine, Gyeongsang National University, Jinju Dae-lo 501, Jinju 660-701, Republic of Korea.
authors.forename: Hyungkyoung
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Pharmacology & Toxicology, College of Veterinary Medicine, Gyeongsang National University, Jinju Dae-lo 501, Jinju 660-701, Republic of Korea.
authors.forename: Changgeun
authors.initials: C
authors.lastname: Kang
authors.affiliation: Department of Pharmacology & Toxicology, College of Veterinary Medicine, Gyeongsang National University, Jinju Dae-lo 501, Jinju 660-701, Republic of Korea.
authors.forename: Yong-San
authors.initials: YS
authors.lastname: Yoo
authors.affiliation: Gyeongnam Livestock Promotion Research Institute, Chojengbuk-lo 104, Jinju 660-985, Gyeongnam, Republic of Korea.
authors.forename: Do-Yun
authors.initials: DY
authors.lastname: Hah
authors.affiliation: Department of Animal Science and Biotechnology, Gyeongnam National University of Science and Technology, Jinju 660-758, Republic of Korea.
authors.forename: Chung Hui
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Department of Pharmacology & Toxicology, College of Veterinary Medicine, Gyeongsang National University, Jinju Dae-lo 501, Jinju 660-701, Republic of Korea.
authors.forename: Euikyung
authors.initials: E
authors.lastname: Kim
authors.affiliation: Department of Pharmacology & Toxicology, College of Veterinary Medicine, Gyeongsang National University, Jinju Dae-lo 501, Jinju 660-701, Republic of Korea. Electronic address: jskim@gnu.ac.kr.
authors.forename: Jong Shu
authors.initials: JS
authors.lastname: Kim
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D015415:Biomarkers / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D019610:Cytoprotection; D004305:Dose-Response Relationship, Drug; D005978:Glutathione / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects*; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation; D015025:Zearalenone / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D018840:HSP70 Heat-Shock Proteins; D017392:Thiobarbituric Acid Reactive Substances; D015025:Zearalenone; D005978:Glutathione
keywords: Chang liver cell; GSH; Heat shock protein 70; Hsp; N-Acetylcysteine amide; N-acetylcysteine amide; NACA; Oxidative stress; TBARS; ZEN; Zearalenone; glutathione; heat stress protein; thiobarbituric acid reactive substance; zearalenone