title: Genotoxic effect and nitrative DNA damage in HepG2 cells exposed to aristolochic acid.
abstract: Aristolochic acid (AA), extensively used as a traditional herbal medicine, was withdrawn from the market in the last century because it was found to be a potent carcinogen in humans and animals. The aim of this study was to evaluate the genotoxic effect of AA and obtain further insight into whether the nitrative DNA damage can be induced by reactive nitrogen species (RNS), including nitric oxide (NO) and its derivative peroxynitrite (ONOO(-)) using human hepatoma HepG2 cells. To identify the genotoxic effect, the comet assay and micronucleus test (MNT) were performed. In the comet assay, 25-200microM of AA caused a significant increase of DNA migration in a dose-dependent manner. A significant increase of the frequency of micronuclei was found in the range between 12.5 and 50microM in the MNT. The results showed that AA caused DNA and chromosome damages. To elucidate the nitrative DNA damage mechanism, the level of nitrite and 8-hydroxydeoxyguanosine (8-OHdG), which can be generated by ONOO(-), were monitored with the 2,3-diaminonaphthalene (DAN) assay and immunoperoxidase staining, respectively. The results showed that AA causes a significant increase in the levels of NO and formation of 8-OHdG at concentrations >/=50microM. This observation supports the assumption that AA could exert genotoxicity probably via NO and its derivatives at higher concentrations in HepG2 cells.
authors.affiliation: Department of Toxicology, Dalian Medical University, 465 Zhongshan Road, Dalian 116027, China.
authors.forename: Keya
authors.initials: K
authors.lastname: Wu
authors.forename: Liping
authors.initials: L
authors.lastname: Jiang
authors.forename: Jun
authors.initials: J
authors.lastname: Cao
authors.forename: Guang
authors.initials: G
authors.lastname: Yang
authors.forename: Chengyan
authors.initials: C
authors.lastname: Geng
authors.forename: Laifu
authors.initials: L
authors.lastname: Zhong
mesh_terms: D034341:Aristolochic Acids / Q000633:toxicity*; D006528:Carcinoma, Hepatocellular / Q000235:genetics; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015162:Micronucleus Tests; D009569:Nitric Oxide / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D034341:Aristolochic Acids; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; C000228:aristolochic acid I