title: Cytogenetic evaluation and the association with polymorphisms of the CPY1A1 and NR1I3 genes in individuals exposed to BTEX.
abstract: The gas station attendants are exposed daily to chemical agents that compose gasoline, such as BTEX (benzene, toluene, ethylbenzene, and xylene), and the exposure to these agents can cause a variety of effects on the human health. Among the various possible cell alterations associated with these exposures are the formation of micronuclei and of binucleated cells which are used as indicators of clastogenic action. Benzene, the main carcinogenic agent, is metabolized to more soluble forms and easily excreted by isoenzymes of cytochrome P450, such as CYP1A1. The CYP1A1 gene is highly polymorphic and one of its allele variations can be detected by the use of restriction endonucleasis MspI and is originated by the transition of a thymine by a cytosine (3798T>C), resulting in the polymorphic allele CYP1A1*2A. The objective of this study was to evaluate the cytogenetic damage induced by the exposure to BTEX and to associate it with the polymorphisms of the CYP1A1 and NR1I3 genes. Samples of exfoliated cells from the oral mucosa of 27 gas station attendants and from a control group were collected. The results found show that the group exposed to BTEX presents significantly higher alterations than those in the control group for micronuclei (MN; 6.85 ± 1.33 vs. 2.96 ± 1.91, P < 0.001) and for the total of nuclear alterations observed (MN + binucleated cells (BNC); 9.59 ± 4.73 vs. 5.07 ± 2.21, P < 0.001). When comparing the cytological alterations and the genotypes among the exposed individuals for the polymorphism 3798T>C of the CYP1A1 gene, homozygotes TT present MN + BNC significantly higher than carriers of the allele C (10.88 ± 5.36 vs. 5.33 ± 2.52, P = 0.028). No association was observed in the control group or for the NR1I3 gene. These results show that molecular and cytogenetic data can be used in the future as tools to monitor individuals exposed to such compounds.
authors.affiliation: Laboratório de Mutagênese e Toxicologia, Centro Universitário Metodista-IPA, Rua Demetrio Ribeiro, 151 Apt 702, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: João Carlos Fraga
authors.initials: JC
authors.lastname: da Rosa
authors.forename: Marilu
authors.initials: M
authors.lastname: Fiegenbaum
authors.forename: Ane Lise
authors.initials: AL
authors.lastname: Soledar
authors.forename: Matheus Souza
authors.initials: MS
authors.lastname: Claus
authors.forename: Antonio Daniel
authors.initials: AD
authors.lastname: de Souza Nunes
authors.forename: Valesca Veiga
authors.initials: VV
authors.lastname: Cardoso
mesh_terms: D000328:Adult; D000395:Air Pollutants, Occupational / Q000633:toxicity*; D001554:Benzene / Q000633:toxicity; D001555:Benzene Derivatives / Q000633:toxicity*; D000090702:Constitutive Androstane Receptor; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D009153:Mutagens / Q000633:toxicity*; D016273:Occupational Exposure / Q000032:analysis*; D020641:Polymorphism, Single Nucleotide; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism; D014050:Toluene / Q000633:toxicity; D014992:Xylenes / Q000633:toxicity; D055815:Young Adult
chemical_list: D000395:Air Pollutants, Occupational; D001555:Benzene Derivatives; D000090702:Constitutive Androstane Receptor; D009153:Mutagens; C000716327:NR1I3 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D014992:Xylenes; D014050:Toluene; D019363:Cytochrome P-450 CYP1A1; D001554:Benzene; C004912:ethylbenzene