Decreased expression of DNA repair genes (XRCC1 and XPD/ERCC2) in colorectal cancer in Iranian patients

Abstract

The aim of this study was to investigate the role of the XRCC1 and XPD/ERCC2 in the susceptibility and in the progression of colorectal cancer (CRC) in Iranian patients. Epidemiological studies have shown a positive association between defective DNA repair capacity and CRC. The underlying mechanism of their involvement is not well understood. In the present study, we have analyzed the relationship between CRC and the expression of DNA repair genes namely X-ray repair cross-complementing group 1 (XRCC1) and xeroderma pigmentosum group D (XPD) in 70 formalin fixed and paraffin embedded tumor tissues as well as normal adjacent tissues. The relative expression of XRCC1 and XPD in the mentioned tissues was performed for first time by quantitative real-time PCR (q-PCR). Results of this study demonstrated that difference of mean relative expression between tumor tissues and normal tissues is 64-fold (XRCC1) > 16-fold (XPD). In multivariate logistic regression analysis, low expression of XRCC1 and XPD was associated with a statistically significant increased risk of CRC [crude odds ratios (ORs) (95%CI) OR 2.10; (1.06-4.17) and OR 5.24 (2.38-11.52), respectively]. In conclusion, our study demonstrated that reduced expression of XRCC1and XPD is associated with more than twofold increased risk in CRC.