title: Genetic polymorphisms in catalase and CYP1B1 determine DNA adduct formation by benzo(a)pyrene ex vivo.
abstract: Genetic polymorphisms can partially explain the large inter-individual variation in DNA adduct levels following exposure to polycyclic aromatic hydrocarbons. Effects of genetic polymorphisms on DNA adduct formation are difficult to assess in human studies because exposure misclassification attenuates underlying relationships. Conversely, ex vivo studies offer the advantage of controlled exposure settings, allowing the possibility to better elucidate genotype-phenotype relationships and gene-gene interactions. Therefore, we exposed lymphocytes of 168 non-smoking volunteers ex vivo to the environmental pollutant benzo(a)pyrene (BaP) and BaP-related DNA adducts were quantified. Thirty-four genetic polymorphisms were assessed in genes involved in carcinogen metabolism, oxidative stress and DNA repair. Polymorphisms in catalase (CAT, rs1001179) and cytochrome P450 1B1 (CYP1B1, rs1800440) were significantly associated with DNA adduct levels, especially when combined. Moreover, reverse transcription-polymerase chain reaction (RT-PCR) analysis in a subset of 30 subjects revealed that expression of catalase correlated strongly with expression of CYP1B1 (R = 0.92, P < 0.001). To further investigate the mechanism by which catalase influences CYP1B1 and how they simultaneously affect BaP-related DNA adduct levels, catalase expression was transiently knocked down in the human lung epithelial cell line A549. Although catalase knockdown did not immediately change CYP1B1 gene expression, recovery of catalase expression 8 h after the knockdown coincided with a 2.2-fold increased expression of CYP1B1 (P < 0.05). We conclude that the genetic polymorphism in the promoter region of CAT may determine the amount and activity of catalase, which may subsequently regulate the expression of CYP1B1. As a result, both genetic polymorphisms modulate DNA adduct levels in lymphocytes by BaP ex vivo.
authors: Department of Toxicology, NUTRIM-School for Nutrition, Toxicology and Metabolism, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands.
authors: Marten A
authors: MA
authors: Schults
authors: Roland K
authors: RK
authors: Chiu
authors: Peter W
authors: PW
authors: Nagle
authors: Lonneke C
authors: LC
authors: Wilms
authors: Jos C
authors: JC
authors: Kleinjans
authors: Frederik J
authors: FJ
authors: van Schooten
authors: Roger W
authors: RW
authors: Godschalk
mesh_terms: D000293:Adolescent; D000328:Adult; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics* / Q000378:metabolism; D001564:Benzo(a)pyrene / Q000633:toxicity*; D002273:Carcinogens / Q000633:toxicity; D002274:Carcinogens, Environmental / Q000633:toxicity; D002374:Catalase / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D020552:Comet Assay; D065633:Cytochrome P-450 CYP1B1; D018736:DNA Adducts / Q000633:toxicity*; D004260:DNA Repair / Q000187:drug effects; D004843:Epistasis, Genetic; D005260:Female; D005786:Gene Expression Regulation; D056726:Genetic Association Studies; D005838:Genotype; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008214:Lymphocytes / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055815:Young Adult
chemical_list: D002273:Carcinogens; D002274:Carcinogens, Environmental; D018736:DNA Adducts; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D012333:RNA, Messenger; C056612:benzo(a)pyrene-DNA adduct; D001564:Benzo(a)pyrene; D002374:Catalase; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D065633:Cytochrome P-450 CYP1B1