Polychlorinated biphenyl quinone-induced genotoxicity, oxidative DNA damage and γ-H2AX formation in HepG2 cells

Abstract

Our previous study has demonstrated that PCB quinone is cytotoxic in HepG2 cells (Toxicology in Vitro 26 (2012) 841–848). However, it is not clear whether PCB quinone is also carcinogenic (or mutagenic). In the current study, we investigated the genotoxicity of PCB quinone (2,3,5-trichloro-6-phenyl-[1,4]benzoquinone, PCB29-pQ) in HepG2 cells using single cell gel electrophoresis (SCGE) assay and micronucleus (MN) assay. We found PCB29-pQ exposure significantly increased olive tail moment (OTM) and micronuclei (MN) frequencies in HepG2 cells. These data suggested that PCB29-pQ caused DNA strand breaks and chromosome breaks. We further investigated whether the genotoxicity of PCB29-pQ is associated with the generation of reactive oxygen species (ROS). Using enzyme-linked immunosorbent assay for 8-hydroxydeoxyguanosine (8-OHdG) detection, we demonstrated that the level of oxidative DNA damage was significantly evaluated with PCB29-pQ exposure concentration and time dependently. Moreover, γ-H2AX appeared after the treatment of PCB29-pQ in HepG2 cells, may indicate double strand breaks (DSBs). In addition, the pretreatment of ROS scavengers inhibited the genotoxicity of PCB29-pQ significantly. In conclusion, our data suggested that PCB29-pQ causes genotoxic effects in HepG2 cells, probably via ROS-induced oxidative DNA damage.