Association of APE1 and hOGG1 polymorphisms with colorectal cancer risk in a Turkish population.

Background: There is growing evidence describing DNA repair genes polymorphisms are related to increased cancer risk including colorectal cancer (CRC). The aim of this study was to investigate the associations between the APE1 Asp148Glu, hOGG1 Ser326Cys, XRCC1 Arg399Gln, XRCC3 Thr241Met, XPD Lys751Gln, XPG Asp1104His polymorphisms and CRC risk in Turkish population.

Patients and Methods: Polymorphisms of APE1 Asp148Glu (rs3136820), hOGG1 Ser326Cys (rs1052133), XRCC1 Arg399Gln(rs25487), XRCC3 Thr241Met (rs861539), XPD Lys751Gln (rs13181), and XPG Asp1104His (rs17655) were determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods in blood samples of 79 CRC patients at their initial staging and 247 healthy controls. Of the CRC patients, 26 out of 40 were diagnosed with rectal cancer and received neoadjuvant chemoradiotherapy following diagnosis; 39 others were diagnosed as colon cancer.

Results: Our preliminary results showed that frequencies of Glu allele of APE1 Asp148Glu and Cys allele of hOGG1 Ser326Cys were higher in CRC patients than in controls (p = 0.006, OR: 3.43; 95% CI: 1.76-6.70; p = 0.000, OR: 2.77; 95% CI: 1.40-5.48, respectively). Higher frequency of Met allele of XRCC3 Thr241Met was detected in patients treated with neoadjuvant chemoradiotherapy (p = 0.024, OR: 5.25; 95% CI: 1.23-23.39) and with proximal colon tumors (p = 0.04, OR: 2; 95% CI: 1.18-3.34). Increased frequency of Ser/Ser genotype of hOGG1 Ser326Cys was found to be associated both with higher grade (p = 0.001, OR: 6.4; 95% CI: 2.69-62.69) and liver metastasis (p = 0.005, OR: 7.5; 95% CI: 0.7-68.36).

Conclusion: APE1 Asp148Glu and hOGG1 Ser326Cys polymorphisms might be associated with increasing risk of CRC in a Turkish population. Future studies with larger-sized samples, as well as detecting the association of DNA repair genes with other confounding factors will help elucidate the exact roles of DNA repair genes polymorphisms in development and progression of CRC.