Influence of Arg399Gln, Arg280His and Arg194Trp XRCC1 gene polymorphisms of Base Excision Repair pathway on the level of 8-oxo-guanine and risk of head and neck cancer in the Polish population

BACKGROUND: Reduced efficiency of DNA repair systems has long been a suspected factor in increasing the risk of cancer. OBJECTIVE: In this work we investigate influence of three selected polymorphisms of DNA repair gene XRCC1 and level of oxidative damage (measured as level of 8-oxo-guanine) on modulation of the risk of HNSCC. METHODS: In group of 359 patients with HNSCC (diagnosed with OSCC) the occurrence of polymorphic variants in Arg399Gln, Arg280His and Arg194Trp of XRCC1 were studied with TaqMan technique. In addition we determined level of 8-oxo-guanine with ELISA. RESULTS: Arg399Gln polymorphism and Arg194Trp polymorphism of XRCC1 gene increases the risk of HNSCC. The coexistence of Arg399Gln and Arg194Trp simultaneously enhances this effect. At the same time, their coexistence with His280His raises the risk to a level higher than in the absence of such coexistence, although the His280His itself is not associated with an increased risk of HNSCC. Patients have higher levels of 8-oxo-guanine than control group, and His280His is polymorphism with highest mean value of 8-oxoG level among studied. CONCLUSION: Patients with HNSCC not only have an increased level of 8-oxoguanine and the Arg399Gln and Arg/Trp of XRCC1 modulate risk of cancer, but there is also a relationship between these two phenomena, and it can be explained using intragenic combinations revealing that a high level of 8-oxoG could be a potential mechanism behind the modulation of HNSCC risk by the polymorphisms studied.

Activated STAT3 Is a Novel Regulator of the XRCC1 Promoter and Selectively Increases XRCC1 Protein Levels in Triple Negative Breast Cancer

Base Excision Repair (BER) addresses base lesions and abasic sites induced by exogenous and endogenous stressors. X-ray cross complementing group 1 (XRCC1) functions as a scaffold protein in BER and single-strand break repair (SSBR), facilitating and coordinating repair through its interaction with a host of critical repair proteins. Alterations of XRCC1 protein and gene expression levels are observed in many cancers, including colorectal, ovarian, and breast cancer. While increases in the expression level of XRCC1 are reported, the transcription factors responsible for this up-regulation are not known. In this study, we identify the signal transducer and activator of transcription 3 (STAT3) as a novel regulator of XRCC1 through chromatin immunoprecipitation. Activation of STAT3 through phosphorylation at Y705 by cytokine (IL-6) signaling increases the expression of XRCC1 and the occupancy of STAT3 within the XRCC1 promoter. In triple negative breast cancer, the constitutive activation of STAT3 upregulates XRCC1 gene and protein expression levels. Increased expression of XRCC1 is associated with aggressiveness and resistance to DNA damaging chemotherapeutics. Thus, we propose that activated STAT3 regulates XRCC1 under stress and growth conditions, but constitutive activation in cancers results in dysregulation of XRCC1 and subsequently BER and SSBR.

The Association between C194T and G399A Polymorphism of XRCC1 Gene and Susceptibility to Gastric Cancer in Population from Western Iran

Background: Gastric cancer is one of the most common malignancies in the world. It may result from a defect in the genes involved in DNA repair. One of the essential genes in the repair pathway is the XRCC1 gene that its polymorphisms in the human population play a role in gastric cancer susceptibility. The main purpose of this study was to investigate the association of 194C/T and 399G/A polymorphisms of the XRCC1 gene with gastric cancer in an Iranian population. Materials and methods: A total of 66 patients with gastric cancer and 67 control individuals were enrolled in our study. Following DNA extraction from blood samples, polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. Results: The allele frequencies of C/T of XRCC1-194C/T in the control and patients groups were 83.17% and 71.29%, respectively. Moreover, The allele frequencies of G/A of XRCC1-399G/A in control and patient groups were 66.34% and 62.38%, respectively. Our results indicated a significant positive association between the distribution T/C alleles and the risk of gastric cancer (χ2: 5.37 and P=0.02), but no significant association was found in the distribution G/A alleles (χ2: 0.47 and P=0.48). Conclusion: Altogether, these findings indicate a positive association between the distribution of 194T/C alleles of XRCC1 and the risk of gastric cancer and the presence of the C allele may increase the risk of gastric cancer.

A DNA Repair Pathway Polymorphism (rs25487) and Angiographically Proven Coronary Artery Patients in a Population of Southern Iran

Background: Coronary artery disease (CAD), which is a multifactorial genetic disease, is known as one of the most common causes of death worldwide. In this regard, X-ray repair cross-complementing group 1 (XRCC1), a DNA repair protein involved in single-strand breaks (SSBs), and base excision repair (BER) pathways have been reported to be responsible for the efficient repair of single strand breaks and damaged bases in DNA. Objective: In the current study, we analyzed Arg399Gln (rs25487), which is one of the most common polymorphism of XRCC1 gene that might be associated with the increased risk for CAD. Method: This case-control study was performed to investigate the relationship between this polymorphism and the CAD development. In this study, 290 patients and 216 controls were diagnosed by cardiac angiography and then screened for the above-mentioned polymorphism using Restriction Fragment Length Polymorphisms (RFLP) method. Results: The frequency of the GA genotype of XRCC1 Arg399Gln (rs25487) was significantly higher in CAD patients compared to the controls (p=0.002, OR: 1.21, 95% CI: 1.06-1.37). Moreover, its dominant mode (AA + GA) genotype had a 1.851-fold increase in the risk of CAD (p = 0.005). Conclusion: Our findings demonstrated that Arg399Gln polymorphism of XRCC1 (rs25487) has a significant relationship with CAD and also plays a probable predisposing role in that. Our results support the role of DNA damages and the malfunctions of DNA repair system in the patients with CAD.

POLYMORPHISMS IN GSTM1, GSTP1 AND GSTT1 GENES AND BREAST CANCER RISK IN WOMEN FROM KYRGYZSTAN

Aim: We studied the intergenic interactions and the contribution of polymorphic loci for GSTT1, GSTM1, GSTP1 genes in the formation of predisposition to breast cancer (ВС) in women of Kyrgyz nationality. Material and method: The study included 87 women of the Kyrgyz ethnic group with the morphologically verified diagnosis of BC and 96 women without cancer and chronic diseases. Genotyping of single-nucleotide polymorphisms (SNPs) was performed using PCR-RFLP for rs1695 GSTP1 gene. Deletion polymophisms in GSTT1 and GSTM1 genes were determined using allele-specific real-time PCR. Analysis of the intergenic interactions conducted with MDR 3.0.2 software. Results: Among women of Kyrgyz nationality, deletion of the GSTM1 gene region is a genetic marker associated with an increased likelihood of developing breast cancer (OR = 2.18, 95% CI 1.38-3.44), p = 0.0007). The absence of deletion in this gene is associated with a protective effect. Analysis of polymorphic markers (GSTT1 gene) and p.Ile105Val (GSTP1 gene) did not reveal statistically significant differences in the frequency distribution of genotypes and alleles between breast cancer patients and women from the comparison group (p > 0.05). Analysis of intergenic interactions using MDR analysis showed that, with the simultaneous presence of the Arg/Gln genotypes (XRCC1 gene) and (GSTM1 gene), the probability of developing breast cancer was - OR = 2.63. Conclusions: Deletion of the GSTM1 gene and combinations of the Arg/Gln genotypes (XRCC1 gene) and (GSTM1 gene) may contribute to the genetic susceptibility of BC in Kyrgyz women.