title: Nrf2/ARE pathway activation, HO-1 and NQO1 induction by polychlorinated biphenyl quinone is associated with reactive oxygen species and PI3K/AKT signaling.
abstract: Nrf2/ARE pathway plays an important role in adapt to oxidative stress caused by pro-oxidants and electrophiles through up-regulating phase II detoxifying enzymes. Our previous study has demonstrated that PCB quinone exposure causes severe cellular oxidative stress (Toxicology In Vitro 26 (2012) 841-848). There are no reports describing the ability of PCB quinone on Nrf2/ARE activation. In the present study, we found that exposure to PCB29-pQ resulted in a significant increase in Nrf2 and Keap1 expression in total protein, as well as the Nrf2 targeting genes, including NQO1 and HO-1. Next, immunocytochemistry analysis identified the accumulation of Nrf2 in nucleus subsequent to PCB29-pQ treatment. The increased Nrf2 and constant Keap1 expression in nucleus suggested the dissociation of Nrf2/Keap1 complex. Similarly, mRNA level of Nrf2 was elevated significantly with PCB29-pQ treatment, but not Keap1. Additionally, PCB29-pQ treatment led to significant up-regulation of the mRNA level of antioxidant enzymes, NQO1 and HO-1, in a concentration-dependent manner. Electrophoretic mobility shift assay and luciferase reporter assay further confirmed the formation of Nrf2-ARE complex. PCB29-pQ treatment has no effect on mitogen-activated protein kinase signaling, however, phospho-AKT was up-regulated and GSK-3β was down-regulated. Pretreatment with LY294002, a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), suppressed the phosphorylation of AKT and inhibited PCB29-pQ induced Nrf2/HO-1 activation, meanwhile, GSK-3β expression was increased accordingly. At last, reactive oxygen species (ROS) scavengers inhibited PCB29-pQ induced Nrf2 activation partly. These results suggested that Nrf2 activation by PCB29-pQ in HepG2 cells is associated with ROS and AKT pathway but not MAPK signaling, the activation of Nrf2/ARE may be an adaptive response to oxidative stress.
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analysis, Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, People's Republic of China.
authors.forename: Lingrui
authors.initials: L
authors.lastname: Li
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analysis, Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Dong
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analysis, Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, People's Republic of China.
authors.forename: Erqun
authors.initials: E
authors.lastname: Song
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analysis, Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, People's Republic of China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Xu
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analysis, Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, People's Republic of China.
authors.forename: Lichao
authors.initials: L
authors.lastname: Liu
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analysis, Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, People's Republic of China. Electronic address: ysong@swu.edu.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: Song
mesh_terms: D016227:Benzoquinones / Q000737:chemistry / Q000633:toxicity; D015153:Blotting, Western; D053492:Elafin / Q000378:metabolism; D004785:Environmental Pollutants / Q000633:toxicity; D004798:Enzymes / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D051547:Heme Oxygenase-1 / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D007150:Immunohistochemistry; D015394:Molecular Structure; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D051058:Oncogene Protein v-akt / Q000378:metabolism*; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D033921:Vesicular Transport Proteins / Q000378:metabolism*
chemical_list: C587734:2,3,5-trichloro-6-phenyl-(1,4)benzoquinone; D016227:Benzoquinones; D053492:Elafin; D004785:Environmental Pollutants; D004798:Enzymes; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C506806:PI3 protein, human; D017382:Reactive Oxygen Species; C115740:VPS52 protein, human; D033921:Vesicular Transport Proteins; D011078:Polychlorinated Biphenyls; D051547:Heme Oxygenase-1; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; D051058:Oncogene Protein v-akt
keywords: HO-1; Keap1; MAPK; NQO1; PCB; ROS