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Objective: To explore the association of the methylation status of MGMT and hMLH1 with chromosome damage induced by vinyl chloride monomer (VCM)., Materials and Methods: Methylation of MGMT and hMLH1 was measured in 101 VCM-exposed workers by methylation-specific PCR. Chromosome damage in peripheral blood lymphocytes was measured by the cytokinesis-block micronucleus assay. The subjects were divided into chromosome damaged and non-damaged groups based on the normal reference value of micronuclei frequencies determined for two control groups., Results: MGMT promoter methylation was detectable in 5 out of 49 chromosome damaged subjects, but not in the chromosome non-damaged subjects; there was a significant difference in MGMT methylation between the two groups (p < 0.05)., Conclusions: We detected aberrant promoter methylation of MGMT in a small number of chromosome damaged VCM-exposed workers, but not in the chromosome non-damaged subjects. This preliminary observation warrants further investigation in a larger study.

Objective: To evaluate the expressions of p53, p21, and CCND1 in the peripheral blood lymphocytes of vinyl chloride monomer (VCM)-exposed workers and potential relationships with their exposures, polymorphisms, and chromosomal aberrations., Methods: The study was performed on 77 occupationally VCM-exposed workers and 43 unexposed controls. The quantities of mRNA expression of p53, p21, and CCND1 genes were detected by real-time polymerase chain reaction., Results: p53 mRNA expression of VCM-low- and high-exposure groups was significantly lower than that of nonexposed group (P < 0.001), but p21 mRNA expression of the two VCM-exposed groups was significantly higher than that of the nonexposed group (P < 0.001). This study did not find the relationship between chromosomal aberrations, genotypes, and the expression of p53, p21, and CCND1., Conclusions: Messenger RNA expressions of p53 and p21 are changed with VCM-exposure status.

Vinyl chloride monomer (VCM) is genotoxic and cancerogen agent. Individual variations in response to the exposure have been noticed and the variations may be due to genetic differences in the removal of VCM-DNA adducts, such as polymorphism in genes NER pathway and BER pathway. This study explores the relationship between genetic polymorphism of seven genes within the NER pathway (XPA, XPD, XPC, XPG, XPF, and ERCC1) and BER pathway (APE1), and susceptibility to chromosomal damage after exposure to VCM. One hundred and eighty workers occupationally exposed to VCM and 43 unexposed controls were investigated. Chromosome damage in peripheral lymphocytes was measured by the cytokinesis-blocked micronucleus assay. PCR-RFLP technique was applied to detect polymorphisms of the seven genes. The influence of genotype, age, gender, cumulative exposure dose, alcohol consumption, and smoking status on the frequencies of MN was determined using univariate and multiple Poisson regression analyses. We found XPA A23G variant workers had significantly higher MN frequencies than those from the wild-type homozygous counterparts (P = 0.01). Those with the variant XPD Lys751Gln genotype had marginally higher MN frequencies (P = 0.07). On the other hand, XPC PAT and XPF 5'-UTR T2063A variant workers had significantly lower MN frequencies compared with those from their wild-type homozygous counterparts (P = 0.04 and P = 0.004, respectively). Our findings suggest that XPC PAT, XPD Lys751Gln, XPA A23G and XPF 5'-UTR T2063A contribute to the level of chromosome damage in occupational exposure to VCM in Chinese population., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

In this study, a group of 313 workers occupationally exposed to vinyl chloride monomer (VCM) and 141 normal unexposed referents were examined for chromosomal damage using the cytokinesis-blocked micronucleus (CBMN) assay in peripheral lymphocytes. We explored the relationship between genetic polymorphisms of XRCC1 (Arg194Trp, Arg280His and Arg399Gln), MGMT(Leu84Phe) and hOGG1 (Ser326Cys) and susceptibility of chromosomal damage induced by VCM. Polymerase chain reaction-restriction fragment length polymorphism techniques were used to detect polymorphisms in XRCC1, hOGG1 and MGMT. It was found that the micronuclei (MN) frequency of exposed workers (4.86 +/- 2.80) per thousand was higher than that of the control group (1.22 +/- 1.24) per thousand (P < 0.01). Increased susceptibility to chromosomal damage as evidenced by higher MN frequency was found in workers with hOGG1 326 Ser/Cys genotype [frequency ratio (FR) = 1.21, 95% confidence interval (CI): 1.02-1.46; P < 0.05], XRCC1 194 Arg/Trp (FR = 1.12, 95% CI: 1.00-1.25; P < 0.05) and XRCC1 280 Arg/His and His/His genotypes (FR = 1.12, 95% CI 1.00-1.26, P < 0.05). Moreover, among susceptibility diplotypes, CGA/CAG carriers had more risk of MN frequency compared with individuals with wild-type CGG/CGG (FR = 1.67, 95% CI: 1.19-2.23; P < 0.05). MN frequency also increased significantly with age in the exposed group (FR = 1.13, 95% CI: 1.00-1.28; P < 0.05). Thus, CB-MN was a sensitive index of early damage among VCM-exposed workers. Genotype XRCC1 Arg194Trp, Arg280His, hOGG1 Ser326Cys, diplotype CGA/CAG and higher age may have an impact on the chromosome damage induced by VCM.

Objective: To evaluate whether polymorphisms in metabolizing enzymes contributed to susceptibility of chromosomal damage induced by vinyl chloride monomer (VCM)., Methods: Cytokinesis block micronucleus test was performed on 185 VCM-exposed workers and 41 control subjects to detect chromosomal damage in peripheral lymphocytes. The polymerase chain reaction and restriction fragment length polymorphism technique was applied to detect polymorphisms of GSTT1, GSTM1, GSTP1G/A, CYP2E1G/C, and CYP2D6G/C. Poisson regression analysis was performed., Results: Sex, age, VCM exposure, GSTP1, and CYP2E1 genotype can influence chromosomal damage. There was a 1.51-fold increased micronucleus frequency for GSTP1GG genotypes individuals compared with those GSTP1AA/GA genotype individuals (P < 0.05), the effect of polymorphism in CYP2E1 gene was more pronounced for allele C compared with allele G (P < 0.05)., Conclusions: Polymorphisms of GSTP1G/A and CYP2E1G/C, which are potential susceptibility biomarkers of chromosomal damage in VCM-exposed worker.

This study explores the relationship between genetic polymorphisms of p53, p21, and CCND1, and the susceptibility of chromosomal damage induced by vinyl chloride monomer (CH(2)=CHCl, VCM). Besides gene polymorphisms, we detected the mRNA expression of p53, p21, and CCND1 in VCM-exposed workers and in a control group. One hundred and eighty-three workers occupationally exposed to VCM were investigated. Chromosome damage in peripheral lymphocyte was measured by cytokinesis-block micronucleus assay. The PCR-restriction fragment length polymorphism technique was applied to detect polymorphisms of p53, p21 (exon 2 and exon 3), and CCND1 genes (exon 4). The quantity of gene mRNA expression was detected by real-time PCR (SYBR Green I). Taking into account the effects of genetic polymorphisms, as well as demographic and habitual factors, Poisson regression analysis showed that the risk of chromosomal damage induced by VCM for individuals carrying the p53 intron 6 heterozygous and mutant homozygous genotype was 1.23 times larger (90% confidence interval, 1.01-1.51 P=0.0814), compared with those carrying wild-type homozygous genotypes. The p53 exon 4, intron 3, and intron 6 haplotype pairs of MMM/WWW (M, mutation allele; W, wild allele), and MWM/WWW were associated with increased frequencies of micronuclei. The p53 mRNA expression of VCM-exposed workers was significantly lower than that of nonexposed workers, but p21 mRNA expression in VCM-exposed workers was significantly higher than that of nonexposed workers. Our findings suggest that the p53 intron 6 polymorphism is one of the factors that potentially influence the frequency of micronuclei induced by VCM.