CORRELATION OF CHROMOSOME DAMAGE AND PROMOTER METHYLATION STATUS OF THE DNA REPAIR GENES MGMT AND HMLH1 IN CHINESE VINYL CHLORIDE MONOMER (VCM)-EXPOSED WORKERS

To explore the association of the methylation status of MGMT and hMLH1 with chromosome damage induced by vinyl chloride monomer (VCM). 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. 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). 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.