Allelic variants of XRCC1 and XRCC3 repair genes and susceptibility of oral cancer in Brazilian patients.

ABSTRACT

BACKGROUND: The capacity for DNA repair is essential in maintaining cellular functions and homeostasis; however, this capacity can be altered based on DNA sequence variations in DNA repair genes, which may contribute to the onset of cancer. Many single-nucleotide polymorphisms (SNPs) in repair genes have been found to be associated with oral cancer. The aim of this study was to investigate the relationship between the presence of allelic variants Arg194Trp (rs1799782) and Arg399Gln (rs 25487) of XRCC1 gene and Thr241Met (rs 861539) of XRCC3 gene and susceptibility to oral cancer. We also attempted to correlate the frequencies obtained for each of the SNPs to histopathological parameters. METHODS: A case-control study was conducted with genomic DNA from 150 patients with oral squamous cell carcinomas and 150 controls. SNPs were genotyped by RFLP-PCR. RESULTS: The presence of the polymorphic variants of the XRCC1 gene within codon 194 (OR 0.82, 95% CI 0.44-1.51) and codon 399 (OR 0.94, 95% CI 0.59-1.50) and within the XRCC3 gene (OR 0.72; 95% CI 0.45-1.16) were not associated with an increased risk of oral cancer. A combinational analysis of SNPs in both genes indicated no association. The presence of the allelic variants of these two genes had no statistically significant effect on tumor differentiation, lymph node invasion or tumor size. CONCLUSIONS: These results suggest that allelic variants of XRCC1 and XRCC3 are not suitable markers for susceptibility to carcinomas of the oral cavity and are also not related to the later stages of such tumors.