The role of XRCC6/Ku70 in nasopharyngeal carcinoma.

The association between XRCC6/Ku70, an upstream player in the DNA double-strand break repair system, and the risk of nasopharyngeal carcinoma (NPC) was examined. In this case-control study, 176 NPC patients and 352 cancer-free controls were genotyped, and the associations of XRCC6 promoter T-991C (rs5751129), promoter G-57C (rs2267437), promoter G-31A (rs132770), and intron 3 (rs132774) polymorphisms with NPC risk were evaluated. NPC tissue samples were also assessed for their XRCC6 mRNA and protein expression by real-time quantitative reverse transcription PCR and Western blotting, respectively. With regard to the XRCC6 promoter T-991C, the TC and CC genotypes were associated with a significantly increased risk of NPC compared with wild-type TT genotype (adjusted odds ratio 2.02 and 3.42, 95% confidence interval 1.21-3.32 and 1.28-8.94, P=0.0072 and 0.0165, respectively). The mRNA and protein expression levels for NPC tissues revealed significantly lower XRCC6 mRNA and protein expression in the NPC samples with TC/CC genotypes compared to those with the TT genotype (P=0.0210 and 0.0164, respectively). These findings suggest that XRCC6 may play an important role in the carcinogenesis of NPC and could serve as a chemotherapeutic target for personalized medicine and therapy.