Current evidence on the relationship between three polymorphisms in the XRCC7 gene and cancer risk

Association between genetic polymorphism of XRCC7 (G6721T) and risk of acute lymphoblastic leukemia

Background

The DNA non-homologous end joining repair gene XRCC7 is one of the most important genes in the DNA double-strand break (DSBs) repair. It is supposed that DNA repair gene malfunction is the main risk factor in various malignancies. The XRCC7 G6721T (rs7003908) polymorphism impact was investigated on the splicing regulation that cause mRNA instability. The goal of the present hospital-based study was to investigate the association between the common genetic polymorphism of XRCC7 G6721T (rs7003908) and risk of acute lymphoblastic leukemia (ALL). This hospital-based case–control study was performed on 99 ALL patients versus 200 healthy children, as the control group, which were frequent matched by age with cases. The polymorphism of XRCC7 was determined using an RFLP-PCR technique.

Results

The GT (OR = 1.485, 95% CI 0.765–2.334, P = 0.243) and TT (OR = 1.655, 95% CI 00.875–3.128, P = 0.121) genotypes had no significant effect on the risk of ALL, in comparison with the GG genotype. However, TT genotype (OR = 1.996, 95% CI 1.033–3.858, P = 0.04) after adjusting for the parents’ smoking pattern showed a significant impact.

Conclusions

These findings suggest that the TT genotype may increase the ALL susceptibility in children when facing with a tobacco smoke.

Polymorphisms of XRCC3 and XRCC7 and Colorectal Cancer Risk in Khorasan Razavi Province, Iran

Background: Colorectal cancer (CRC) is highly prevalent cancer, which should be genetically studied among different peoples of the world. Objective: The aim of this study was to evaluate the effect of XRCC3T241M, XRCC3 A17893G and, for the first time, XRCC7 I3434T polymorphisms on CRC risk in Khorasan Razavi Province, Iran. Materials and Methods: In this case-control study, 180 patients with CRC and 160 sex- and age-matched healthy controls were studied. Genotypes were determined by RFLP-PCR and ARMS-PCR. Results: The incidence of CRC was observed to be significantly more in a heterozygous XRCC3 C/T genotype than in the CC genotype (OR 2.210, 95% CI 1.073-4.548, p=0.030). In the case of the XRCC7 I3434T polymorphism, CRC risk was significantly (4.3 fold) higher in I/T+T/T variant subjects compared to the I/I genotype (OR 4.394, 95% CI 2.721-7.096, p=0.000). Moreover, the XRCC3 A17893G polymorphism did not correlate with CRC. In addition, there was no significant difference between the distribution of genotypes of the three studied polymorphisms with demographic and clinicopathological features in the CRC patients. Conclusion: Polymorphisms of XRRC3 and XRCC7 genes are involved in CRC and should be considered as a risk factor.

XRCC7 rs#7003908 Polymorphism and Helicobacter pylori Infection-Related Gastric Antrum Adenocarcinoma

The X-ray repair cross-complementing group 7 (XRCC7) plays a key role in DNA repair that protects against genetic instability and carcinogenesis. To determine whether XRCC7 rs#7003908 polymorphism (XRCC7P) is associated with Helicobacter pylori (H. pylori) infection-related gastric antrum adenocarcinoma (GAA) risk, we conducted a hospital-based case-control study, including 642 patients with pathologically confirmed GAA and 927 individually matched controls without any evidence of tumours or precancerous lesions, among Guangxi population. Increased risks of GAA were observed for individuals with cagA positive (odds ratio (OR) 6.38; 95% confidence interval (CI) 5.03–8.09). We also found that these individuals with the genotypes of XRCC7 rs#7003908 G alleles (XRCC7-TG or -GG) featured increasing risk of GAA (ORs 2.80 and 5.13, resp.), compared with the homozygote of XRCC7 rs#7003908 T alleles (XRCC7-TT). GAA risk, moreover, did appear to differ more significantly among individuals featuring cagA-positive status, whose adjusted ORs (95% CIs) were 15.74 (10.89–22.77) for XRCC7-TG and 38.49 (22.82–64.93) for XRCC7-GG, respectively. Additionally, this polymorphism multiplicatively interacted with XRCC3 codon 241 polymorphism with respect to HCC risk (OR_interaction = 1.49). These results suggest that XRCC7P may be associated with the risk of Guangxiese GAA related to cagA.