title: Genetic polymorphisms of DNA repair and xenobiotic-metabolizing enzymes: role in mutagen sensitivity.
abstract: Mutagen sensitivity, measuring the extent of chromosome damage induced by an in vitro treatment of peripheral lymphocytes with bleomycin, has been associated with an increased risk of various human cancers. Sensitivity to bleomycin appears to have high heritability and is usually considered to reflect individual capacity to repair DNA lesions. Another potential contributor to variation in bleomycin sensitivity could be inherited differences in the metabolism of bleomycin. We assessed whether genetic polymorphisms of DNA repair and xenobiotic-metabolizing enzymes (XMEs) could explain bleomycin sensitivity. Frequencies of bleomycin-induced chromatid breaks per cell (b/c) were determined for 80 healthy Caucasians. Genotypes of DNA repair genes XRCC (X-ray repair cross-complementing) 1 and 3 and XME genes bleomycin hydrolase (BLHX), glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) and N-acetyltransferase 2 (NAT2) were analyzed from leukocyte DNA using methods based on polymerase chain reaction. The mean number of chromatid b/c was increased in individuals with XRCC1 codon 280 variant allele (P = 0.002; two-sided Mann-Whitney test). Smokers carrying BLHX codon 1450 variant allele showed a decrease in the mean number of chromatid b/c (P = 0.036). In multiple linear regression models including adjustment for age, sex, smoking and genotype, the adjusted relative risks (and 95% confidence intervals) were 1.18 (0.98-1.41) and 0.84 (0.69-1.00) for carriers of XRCC1 codon 280 and BLHX codon 1450 variant alleles, respectively. XRCC1 codon 280 polymorphism had a significant effect (P = 0.012) in predetermining whether the individual was classified as non-sensitive, sensitive or hypersensitive to bleomycin. Although based on relatively few individuals, our results suggest that bleomycin sensitivity is partially explained by genetic polymorphisms affecting DNA repair (XRCC1) and in vitro metabolism of bleomycin (BLHX).
authors.affiliation: Laboratory of Molecular and Cellular Toxicology, Department of Industrial Hygiene and Toxicology, Finnish Institute of Occupational Health, FIN-00250 Helsinki, Finland.
authors.forename: Jarno
authors.initials: J
authors.lastname: Tuimala
authors.forename: Gabor
authors.initials: G
authors.lastname: Szekely
authors.forename: Sarolta
authors.initials: S
authors.lastname: Gundy
authors.forename: Ari
authors.initials: A
authors.lastname: Hirvonen
authors.forename: Hannu
authors.initials: H
authors.lastname: Norppa
mesh_terms: D001191:Arylamine N-Acetyltransferase / Q000187:drug effects / Q000235:genetics; D001761:Bleomycin / Q000633:toxicity; D002842:Chromatids / Q000187:drug effects; D002869:Chromosome Aberrations / Q000187:drug effects*; D004247:DNA / Q000097:blood; D004260:DNA Repair / Q000235:genetics*; D005260:Female; D005838:Genotype; D005982:Glutathione Transferase / Q000187:drug effects / Q000235:genetics; D006801:Humans; D006814:Hungary; D007962:Leukocytes / Q000502:physiology; D008297:Male; D009152:Mutagenicity Tests; D009153:Mutagens / Q000494:pharmacology*; D011110:Polymorphism, Genetic; D012306:Risk; D044465:White People; D015262:Xenobiotics / Q000493:pharmacokinetics*
chemical_list: D001191:Arylamine N-Acetyltransferase; D001761:Bleomycin; D004247:DNA; D005982:Glutathione Transferase; D009153:Mutagens; D015262:Xenobiotics; C478900:NAT2 protein, human; C413545:glutathione S-transferase T1