title: PCB126 enhanced the genotoxicity of BaP in HepG2 cells by modulating metabolic enzyme and DNA repair activities.
abstract: Both of benzo(a)pyrene (BaP) and 3,3',4,4',5-pentachlorobiphenyl (PCB126) are ubiquitous and persistent environmental pollutants. These two chemicals coexist in various environmental media and human samples and thus may have combined effects on human health. However, the toxic effects and related mechanism of co-exposure to BaP and PCB126 remain unknown. In a series of experiments using the HepG2 cells exposed to BaP (50microM) or/and PCB126 (0.01, 0.1, 1 and 10nM), we measured the rate of micronucleus (MN) formation, CYP1A1 activity and expression of nucleotide excision repair (NER) proteins (XPA and XPC). We found that the exposure to BaP or PCB126 alone could effectively increase the CYP1A1 activity and the XPA expression. BaP alone had a profound enhancement of MN formation. Compared with BaP alone, co-exposure to both BaP and PCB126 significantly enhanced the CYP1A1 activity and the formation of MN but reduced the expression of both XPA and XPC. The synergistic effect of PCB126 on BaP-induced MN formation was inhibited by alpha-naphthoflavone (ANF), an inhibitor of CYP1A1. Our findings suggest that PCB126 may enhance BaP-induced DNA damage and genotoxicity by increasing cytochrome P450 1A activity and decreasing the NER capacity.
authors: Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei, PR China.
authors: Wei
authors: W
authors: Wei
authors: Chi
authors: C
authors: Zhang
authors: Ai-Lin
authors: AL
authors: Liu
authors: Shao-Hua
authors: SH
authors: Xie
authors: Xue-Min
authors: XM
authors: Chen
authors: Wen-Qing
authors: WQ
authors: Lu
mesh_terms: D001564:Benzo(a)pyrene / Q000008:administration & dosage / Q000633:toxicity*; D045744:Cell Line, Tumor; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004785:Environmental Pollutants / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D048629:Micronuclei, Chromosome-Defective / Q000187:drug effects; D015162:Micronucleus Tests; D011078:Polychlorinated Biphenyls / Q000008:administration & dosage / Q000633:toxicity*; D051760:Xeroderma Pigmentosum Group A Protein / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D004785:Environmental Pollutants; C497314:XPA protein, human; D051760:Xeroderma Pigmentosum Group A Protein; C086984:XPC protein, human; D001564:Benzo(a)pyrene; D011078:Polychlorinated Biphenyls; D019363:Cytochrome P-450 CYP1A1; C023035:3,4,5,3',4'-pentachlorobiphenyl