title: Involvement of reactive oxygen species in Microcystin-LR-induced cytogenotoxicity.
abstract: Microcystin-LR (MCLR) is a potent hepatotoxin. Oxidative stress is thought to be implicated in the cytotoxicity of MCLR, but the mechanisms by which MCLR produces reactive oxygen species (ROS) are still unclear. This study investigated the role and possible sources of ROS generation in MCLR-induced cytogenotoxicity in HepG2, a human hepatoma cell line. MCLR increased DNA strand breaks, 8-hydroxydeoxiguanosine formation, lipid peroxidation, as well as LDH release, all of which were inhibited by ROS scavengers. ROS scavengers partly suppressed MCLR-induced cytotoxicity determined by the MTT assay. MCLR induced the generation of ROS, as confirmed by confocal microscopy with 2-[6-(4'-hydroxy)phenoxy-3H-xanthen-3-on-9-yl]benzoic acid, and upregulated the expression of CYP2E1 mRNA. In addition, CYP2E1 inhibitors chlormethiazole and diallyl dulphide inhibited both ROS generation and cytotoxicity induced by MCLR. The results suggest that ROS contribute to MCLR-induced cytogenotoxicity. CYP2E1 might be a potential source responsible for ROS generation by MCLR.
authors.affiliation: Department of Environmental Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Nong
authors.forename: Masaharu
authors.initials: M
authors.lastname: Komatsu
authors.forename: Kimiko
authors.initials: K
authors.lastname: Izumo
authors.forename: Hiroko P
authors.initials: HP
authors.lastname: Indo
authors.forename: Baohui
authors.initials: B
authors.lastname: Xu
authors.forename: Kohji
authors.initials: K
authors.lastname: Aoyama
authors.forename: Hideyuki J
authors.initials: HJ
authors.lastname: Majima
authors.forename: Masahisa
authors.initials: M
authors.lastname: Horiuchi
authors.forename: Kanehisa
authors.initials: K
authors.lastname: Morimoto
authors.forename: Toru
authors.initials: T
authors.lastname: Takeuchi
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D001427:Bacterial Toxins / Q000633:toxicity*; D006528:Carcinoma, Hepatocellular; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D020552:Comet Assay; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008113:Liver Neoplasms; D008387:Marine Toxins; D052998:Microcystins / Q000633:toxicity*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; D008387:Marine Toxins; D052998:Microcystins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003577:Cytochrome P-450 Enzyme System; D007770:L-Lactate Dehydrogenase; C057862:cyanoginosin LR; D003849:Deoxyguanosine