DNA repair gene XRCC3 polymorphisms and cancer risk: a meta-analysis of 48 case-control studies

Interactive Association of XRCC1, XRCC2, XRCC3, and TP53 Gene Polymorphisms With Gastrointestinal Cancer Risk: Insights From a Hospital-Based Case-Control Study

BACKGROUND AND AIM

Gastrointestinal (GI) cancer presents a significant worldwide health burden, influenced by a combination of genetic and environmental factors. This study endeavors to explore the combined effects of the XRCC1, XRCC2, XRCC3, and TP53 genes that contribute to the heightened risk of GI cancer, shedding light on their combined influence on cancer susceptibility.

MATERIALS AND METHODS

A total of 200 histologically confirmed cases of GI cancer and an equal number of controls were selected to examine genetic polymorphisms within the XRCC1, XRCC2, XRCC3, and TP53 genes using the polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP). Odds ratios (OR) with 95% confidence intervals (CI) were calculated to assess the association of these polymorphisms with GI cancer susceptibility, with statistical significance (p ≤ 0.05).

RESULTS

Logistic regression analysis confirmed strong evidence of synergistic interactions among specific variant genotypes. Notably, combinations such as heterozygous Arg/Ser+Ser/Ser genotype of TP53 Arg249Ser polymorphism with Arg/Trp+Trp/Trp genotype of XRCC1 Arg194Trp polymorphism (OR=2.64; 95% CI: 1.35-5.18; p=0.004), Arg/Gln+Gln/Gln genotype of XRCC1 at codon 399 (OR=5.04; 95% CI: 2.81-9.05; p=0.0001), Arg/His and His/His genotypes of XRCC2 Arg188His (OR=2.16; 95% CI: 1.06-4.39; p<0.032), and Thr/Met+Met/Met genotype of XRCC3 Thr242Met (OR=3.48; 95% CI: 1.79-6.77; p=0.0002) showed significant associations with GI cancer risk in the study population.

CONCLUSIONS

The findings indicate a notable association between the combined effect of heterozygous variant genotypes of TP53 and variant genotypes of XRCC1, XRCC2, and XRCC3 on GI cancer risk. However, further research with a larger sample size and broad single nucleotide polymorphism (SNP) spectra is necessary to understand the interaction between genetic variations and environmental factors influencing GI cancer susceptibility.

Association of RAD51, XRCC1, XRCC2, and XRCC3 Polymorphisms with Risk of Breast Cancer

Background: DNA repair genes are among the low-penetrance genes implicated in breast cancer. However variants of DNA repair genes may alter their protein function thus leading to carcinogenesis. Breast cancer is the most common cancer among women in India. The aim of the present study was to identify association, if any, of single nucleotide polymorphisms (SNP's) in four genes involved in DNA repair pathways including, RAD51 rs1801320, XRCC1 rs25487, XRCC2 rs3218536, and XRCC3 rs861539 with the risk of breast cancer. Materials and Methods: In this case-control study 611 female subjects (311 breast cancer patients and 300 healthy controls) were screened for four SNPs using polymerase chain reaction-restriction fragment length polymorphism analyses. Multifactor dimensionality reduction (MDR) analysis was performed to estimate the gene-gene interaction. Protein-protein interaction network analysis were studied using the STRING database. Results: The GC genotype (p = 0.018) and the combined GC+CC (p = 0.03) genotypes of RAD51 rs1801320 were significantly associated with reduced risk of breast cancer. The CT genotype (p = 0.0001), the combined CT+TT genotypes (p = 0.0002), and the T allele (p = 0.0019) of XRCC3 rs861539 polymorphism were associated with reduced risk of the breast cancer. No association of XRCC1 rs25487 and XRCC2 rs3218536 polymorphisms with breast cancer was observed. MDR analysis indicated a positive interaction between XRCC3 and XRCC2. String network analysis showed that the RAD51, XRCC1, XRCC2, and XRCC3 proteins are in strong interaction with each other and other breast cancer-related proteins such as BRCA2. Conclusion: RAD51 rs1801320 and XRCC3 rs861539 polymorphisms were associated with reduced risk of breast cancer. There is evidence of positive interactions among XRCC1, XRCC2, XRCC3, and RAD51.

Association of buccal micronucleus cytome assay (BMNCyt) biomarkers with inorganic element concentration and genetic polymorphisms in welders

Welding fumes are classified as carcinogenic to humans. The aim of the present study was to measure buccal micronucleus cytome assay biomarkers and to evaluate their association with inorganic elements and genetic polymorphisms (XRCC1, OGG1, XRCC3, GSTM1, and GSTT1) in welders (n = 98) and control individuals (n = 100). Higher levels of DNA damage and cell death were observed in the exposed group. Also, a significant correlation between the frequency of micronuclei and Na, Si, Cl, Ti, Cr, Zn and Mg concentrations. The formation of micronuclei, binucleated cells, cell death was associated with polymorphisms in repair pathways. The OGG1Ser326Cys and XRCC3 241Thr/Met genotypes were associated with cell death. Individuals with GSTM1 null genotype had a higher frequency of micronuclei. These results demonstrate that the deleterious effects of exposure to welding fumes are exacerbated by lifestyle habits, and genetic polymorphisms can influence DNA damage and cell death.

Association between XRCC3 p.Thr241Met polymorphism and risk of glioma: A systematic review and meta-analysis

BACKGROUND

The XRCC3 p.Thr241Met (rs861539) polymorphism has been extensively studied for its association with glioma risk, but results remain conflicting. Therefore, we performed a systematic review and meta-analysis to resolve this inconsistency.

METHODS

Studies published up to June 10, 2022, were searched in PubMed, Web of Science, Scopus, VIP, Wanfang, and China National Knowledge Infrastructure databases and screened for eligibility. Then, the combined odds ratio (OR) of the included studies was estimated based on five genetic models, i.e., homozygous (Met/Met vs. Thr/Thr), heterozygous (Thr/Met vs. Thr/Thr), dominant (Thr/Met + Met/Met vs. Thr/Thr), recessive (Met/Met vs. Thr/Thr + Thr/Met) and allele (Met vs. Thr). The study protocol was preregistered at PROSPERO (registration number: CRD42021235704).

RESULTS

Overall, our meta-analysis of 14 eligible studies involving 12,905 subjects showed that the p.Thr241Met polymorphism was significantly associated with increased glioma risk in both homozygous and recessive models (homozygous, OR = 1.381, 95% CI = 1.081-1.764, P = 0.010; recessive, OR = 1.305, 95% CI = 1.140-1.493, P<0.001). Subgroup analyses by ethnicity also revealed a statistically significant association under the two aforementioned genetic models, but only in the Asian population and not in Caucasians (P>0.05).

CONCLUSION

We demonstrated that the XRCC3 p.Thr241Met polymorphism is associated with an increased risk of glioma only in the homozygous and recessive models.

NBN, RAD51 and XRCC3 Polymorphisms as Potential Predictive Biomarkers of Adjuvant Radiotherapy Toxicity in Early HER2-Positive Breast Cancer

Simple Summary

Adjuvant radiotherapy for breast cancer patients significantly improves survival and causes side effects. It is known that the response to radiotherapy is individual, but we are not yet able to predict patients with high risk for acute or late radiotherapy adverse events. This study aimed to investigate the association between homologous recombination repair (HRR) polymorphisms and radiotherapy toxicity and thus contribute to the knowledge on potential predictive biomarkers of radiotherapy toxicity in early HER2-positive breast cancer. This study was among the first to evaluate the role of HRR genetic variability with cardiac toxicity. RAD51 polymorphisms were associated with cardiac adverse events, while XRCC3 polymorphisms were associated with skin adverse events. Our results suggest that polymorphisms in key HRR genes might be used as potential biomarkers of late treatment-related adverse events in early HER2-positive breast cancer treated with radiotherapy.

Abstract

Radiotherapy (RT) for breast cancer significantly impacts patient survival and causes adverse events. Double-strand breaks are the most harmful type of DNA damage associated with RT, which is repaired through homologous recombination (HRR). As genetic variability of DNA repair genes could affect response to RT, we aimed to evaluate the association of polymorphisms in HRR genes with tumor characteristics and the occurrence of RT adverse events in early HER2-positive breast cancer. Our study included 101 breast cancer patients treated with adjuvant RT and trastuzumab. All patients were genotyped for eight single nucleotide polymorphisms in NBN, RAD51 and XRCC3 using competitive allele-specific PCR. Carriers of XRCC3 rs1799794 GG genotype were less likely to have higher tumor differentiation grade (OR = 0.05, 95% CI = 0.01–0.44, p = 0.007). Carriers of RAD51 rs1801321 TT genotype were more likely to have higher NYHA class in univariable (OR = 10.0; 95% CI = 1.63–61.33; p = 0.013) and multivariable (OR = 9.27; 95% CI = 1.28–67.02; p = 0.027) analysis. Carriers of RAD51 rs12593359 GG genotype were less likely to have higher NYHA class in univariable (OR = 0.09; 95% CI = 0.01–0.79; p = 0.030) and multivariable (OR = 0.07; 95% CI = 0.01–0.81; p = 0.034) analysis. Carriers of XRCC3 rs1799794 GG genotypes experienced more skin adverse events based on LENT-SOMA scale in univariable (OR = 5.83; 95% CI = 1.22–28.00; p = 0.028) and multivariable (OR = 10.90; 95% CI = 1.61–73.72; p = 0.014) analysis. In conclusion, XRCC3 and RAD51 polymorphisms might contribute to RT adverse events in early HER2-positive breast cancer patients.

The association between XRCC3 rs1799794 polymorphism and cancer risk: a meta-analysis of 34 case-control studies

BACKGROUND

Studies on the XRCC3 rs1799794 polymorphism show that this polymorphism is involved in a variety of cancers, but its specific relationships or effects are not consistent. The purpose of this meta-analysis was to investigate the association between rs1799794 polymorphism and susceptibility to cancer.

METHODS

PubMed, Embase, the Cochrane Library, Web of Science, and Scopus were searched for eligible studies through June 11, 2019. All analyses were performed with Stata 14.0. Subgroup analyses were performed by cancer type, ethnicity, source of control, and detection method. A total of 37 studies with 23,537 cases and 30,649 controls were included in this meta-analysis.

RESULTS

XRCC3 rs1799794 increased cancer risk in the dominant model and heterozygous model (GG + AG vs. AA: odds ratio [OR] = 1.04, 95% confidence interval [CI] = 1.00-1.08, P = 0.051; AG vs. AA: OR = 1.05, 95% CI = 1.00-1.01, P = 0.015). The existence of rs1799794 increased the risk of breast cancer and thyroid cancer, but reduced the risk of ovarian cancer. In addition, rs1799794 increased the risk of cancer in the Caucasian population.

CONCLUSION

This meta-analysis confirms that XRCC3 rs1799794 is related to cancer risk, especially increased risk for breast cancer and thyroid cancer and reduced risk for ovarian cancer. However, well-designed large-scale studies are required to further evaluate the results.

DNA repair and metabolic gene polymorphisms affect genetic damage due to diesel engine exhaust exposure

Diesel engine exhaust (DEE) is a complex mixture of toxic gases, halogenated aromatic hydrocarbons, alkyl polycyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, benzene derivatives, metals and diesel exhaust particles (DEPs) generated from the incomplete combustion of diesel fuel. Many of the compounds in this mixture can cause oxidative damage to DNA and are considered carcinogenic for humans. Further, chronic DEE exposure increases risks of cardiovascular and pulmonary diseases. Despite these pervasive health risks, there is limited and inconsistent information regarding genetic factors conferring susceptibility or resistance to DEE genotoxicity. The present study evaluated the effects of polymorphisms in two base excision repair (BER) genes (OGG1 Ser326Cys and XRCC1 Arg280His), one homologous recombination (HRR) gene (XRCC3 Thr241Met) and two xenobiotic metabolism genes (GSTM1 and GSTT1) on the genotoxicity profiles among 123 mechanics exposed to workplace DEE. Polymorphisms were determined by PCR-RFLP. In comet assay, individuals with the GSTT1 null genotype demonstrated significantly greater % tail DNA in lymphocytes than those with non-null genotype. In contrast, these null individuals exhibited significantly lower frequencies of binucleated (BN) cells and nuclear buds (NBUDs) in buccal cells than non-null individuals. Heterozygous hOGG1 326 individuals (hOGG1 326 Ser/Cys) exhibited higher buccal cell NBUD frequency than hOGG1 326 Ser/Ser individuals. Individuals carrying the XRCC3 241 Met/Met polymorphism also showed significantly higher buccal cell NBUD frequencies than those carrying the XRCC3 241 Thr/Thr polymorphism. We found a high flow of particulate matter with a diameter of < 2.5 μm (PM_2.5) in the workplace. The most abundant metals in DEPs were iron, copper, silicon and manganese as detected by transmission electron microscopy-energy-dispersive X-ray spectroscopy (TEM-EDX). Scanning electron microscopy (SEM-EDS) revealed particles with diameters smaller than PM_2.5, including nanoparticles forming aggregates and agglomerates. Our results demonstrate the genotoxic effects of DEE and the critical influence of genetic susceptibility conferred by DNA repair and metabolic gene polymorphisms that shed light into the understanding of underlying mechanisms.

Associations between XRCC3 Thr241Met polymorphisms and breast cancer risk: systematic-review and meta-analysis of 55 case-control studies

BACKGROUND

The X-ray repair cross-complementing group 3 (XRCC3) is an efficient component of homologous recombination and is required for the preservation of chromosomal integrity in mammalian cells. The association between Thr241Met single-nucleotide polymorphism (SNP) in this gene and susceptibility to breast cancer has been assessed in several studies. Yet, reports are controversial. The present meta-analysis has been designed to identify whether this SNP is associated with susceptibility to breast cancer.

METHODS

We performed a systematic review and meta-analysis for retrieving the case-control studies on the associations between T241 M SNP and the risk of breast cancer. Crude odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to verify the association in dominant, recessive, and homozygote inheritance models.

RESULTS

We included 55 studies containing 30,966 sporadic breast cancer cases, 1174 familial breast cancer cases and 32,890 controls in the meta-analysis. In crude analyses, no association was detected between the mentioned SNP and breast cancer risk in recessive, homozygote or dominant models. However, ethnic based analysis showed that in sporadic breast cancer, the SNP was associated with breast cancer risk in Arab populations in homozygous (OR (95% CI) = 3.649 (2.029-6.563), p = 0.0001) and recessive models (OR (95% CI) = 4.092 (1.806-9.271), p = 0.001). The association was significant in Asian population in dominant model (OR (95% CI) = 1.296, p = 0.029). However, the associations was significant in familial breast cancer in mixed ethnic-based subgroup in homozygote and recessive models (OR (95% CI) = 0.451 (0.309-0.659), p = 0.0001, OR (95% CI) = 0.462 (0.298-0.716), p = 0.001 respectively).

CONCLUSIONS

Taken together, our results in a large sample of both sporadic and familial cases of breast cancer showed insignificant role of Thr241Met in the pathogenesis of this type of malignancy. Such results were more conclusive in sporadic cases. In familial cases, future studies are needed to verify our results.

Cytogenetic effects of radiation and genetic polymorphisms of the XRCC1 and XRCC3 repair genes in industrial radiographers

Different types of DNA damages caused by ionizing radiation may enhance the cancer risk in exposed individuals. Inherited variations in DNA repair genes cause the inter-individual variability in response to ionizing radiation. The purpose of this study was to determine the association between single nucleotide polymorphism (SNP) of two important DNA repair genes (XRCC1 R399Q and XRCC3 T241M) and the level of DNA damage investigated by micronucleus (MN) frequency in peripheral blood lymphocytes of 120 industrial radiographers (IR) and 120 non-exposed control individuals. The frequencies of MN and nucleoplasmic bridges were significantly higher in the IR group than in the control group (33.83 ± 11.96 vs. 7.47 ± 2.96, p < 0.0001 and 1.69 ± 1.86 vs. 0.12 ± 0.33, p < 0.0001). MN frequencies in the IR group were associated with the cumulative radiation doses (p < 0.0001, r = 0.58 for last 1 year of exposure and p < 0.0001, r = 0.67 for last 5 years of exposure). Polymorphism of XRCC3 T241M was associated with higher MN frequencies in the IR group. However, the same result was not observed between XRCC3 SNP and MN frequency in the control group. Consequently, XRCC3 241Met alleles may cause the increased DNA damage in the industrial radiographers.

Bladder Cancer Genetic Susceptibility. A Systematic Review

Background:

The variant/gene candidate approach to explore bladder cancer (BC) genetic susceptibility has been applied in many studies with significant findings reported. However, results are not always conclusive due to the lack of replication by subsequent studies.

Objectives:

To identify all epidemiological investigations on the genetic associations with BC risk, to quantify the likely magnitude of the associations by applying metaanalysis methodology and to assess whether there is a potential for publication/reporting bias.

Methods:

To address our aims, we have catalogued all genetic association studies published in the field of BC risk since 2000. Furthermore, we metaanalysed all polymorphisms with data available from at least three independent case-control studies with subjects of Caucasian origin analyzed under the same mode of inheritance.

Results:

The characterization of the genetic susceptibility of BC is composed of 28 variants, GWAS contributing most of them. Most of the significant variants associated with BC risk are located in genes belonging to chemical carcinogenesis, DNA repair, and cell cycle pathways. Causal relationship was also provided by functional analysis for GSTM1-null, NAT2-slow, APOBEC-rs1014971, CCNE1-rs8102137, SLC14A1-rs10775480, PSCA-rs2294008, UGT1A-rs1189203, and TP63-rs35592567.

Conclusions:

Genetic susceptibility of BC is still poorly defined, with GWAS contributing most of the strongest evidence. The systematic review did not provide evidence of further genetic associations. The potential public health translation of the existing knowledge on genetic susceptibility on BC is still limited.

Single nucleotide polymorphisms in DNA repair genes and putative cancer risk

Single nucleotide polymorphisms (SNPs) are the most frequent type of genetic alterations between individuals. An SNP located within the coding sequence of a gene may lead to an amino acid substitution and in turn might alter protein function. Such a change in protein sequence could be functionally relevant and therefore might be associated with susceptibility to human diseases, such as cancer. DNA repair mechanisms are known to play an important role in cancer development, as shown in various human cancer syndromes, which arise due to mutations in DNA repair genes. This leads to the question whether subtle genetic changes such as SNPs in DNA repair genes may contribute to cancer susceptibility. In numerous epidemiological studies, efforts have been made to associate specific SNPs in DNA repair genes with altered DNA repair and cancer. The present review describes some of the common and most extensively studied SNPs in DNA repair genes and discusses whether they are functionally relevant and subsequently increase the likelihood that cancer will develop.

Quantitative assessment of the influence of X-ray repair cross-complementing group 3 rs861539 polymorphism and cutaneous melanoma susceptibility

Previous studies evaluating the association between X-ray repair cross-complementing group 3 (XRCC3) rs861539 polymorphism and cutaneous melanoma susceptibility reported conflicting findings. To draw a more precise association between XRCC3 rs861539 polymorphism and cutaneous melanoma susceptibility, we searched PubMed, EMBASE and Web of Science for case-control studies. A total of eight case-control studies including 3463 cases of melanoma and 4216 controls were included in the meta-analysis. Overall, no significant associations were found between XRCC3 rs861539 polymorphism and cutaneous melanoma susceptibility under all four genetic models (TT vs CC: OR 0.99, 95 % CI 0.86-1.14; TC vs CC: OR 0.92, 95 % CI 0.83-1.01; dominant model: OR 0.94, 95 % CI 0.85-1.03; recessive model: OR 1.05, 95 % CI 0.92-1.19). In the subgroup by source of control, no significant associations were found in hospital-based and population-based subgroup. This meta-analysis suggested that the XRCC3 rs861539 polymorphism was not a risk factor for cutaneous melanoma susceptibility.

Subclinical carotid atherosclerosis and early vascular aging from long-term low-dose ionizing radiation exposure: a genetic, telomere, and vascular ultrasound study in cardiac catheterization laboratory staff

OBJECTIVES

This study sought to assess the association between long-term radiation exposure in the catheterization laboratory (cath lab) and early signs of subclinical atherosclerosis.

BACKGROUND

There is growing evidence of an excess risk of cardiovascular disease at low-dose levels of ionizing radiation exposure.

METHODS

Left and right carotid intima-media thickness (CIMT) was measured in 223 cath lab personnel (141 male; age, 45 ± 8 years) and 222 unexposed subjects (113 male; age, 44±10 years). Leukocyte telomere length (LTL) was evaluated by quantitative reverse transcriptase polymerase chain reaction. The DNA repair gene XRCC3 Thr241Met polymorphism was also analyzed to explore the possible interaction with radiation exposure. The occupational radiological risk score (ORRS) was computed for each subject on the basis of the length of employment, individual caseload, and proximity to the radiation source. A complete lifetime effective dose (mSv) was recorded for 57 workers.

RESULTS

Left, right, and averaged CIMTs were significantly increased in high-exposure workers compared with both control subjects and low-exposure workers (all p values<0.04). On the left side, but not on the right, there was a significant correlation between CIMT and ORRS (p=0.001) as well as lifetime dose (p=0.006). LTL was significantly reduced in exposed workers compared with control subjects (p=0.008). There was a significant correlation between LTL and both ORRS (p=0.002) and lifetime dose (p=0.03). The XRCC3 Met241 allele presented a significant interaction with high exposure for right side (pinteraction=0.002), left side (pinteraction<0.0001), and averaged (pinteraction<0.0001) CIMTs.

CONCLUSIONS

Long-term radiation exposure in a cath lab may be associated with increased subclinical CIMT and telomere length shortening, suggesting evidence of accelerated vascular aging and early atherosclerosis.

Polymorphisms in DNA Repair Gene XRCC3 and Susceptibility to Breast Cancer in Saudi Females

We investigated three common polymorphisms (SNPs) in the XRCC3 gene (rs861539, rs1799794, and rs1799796) in 143 Saudi females suffering from breast cancer (median age = 51.4 years) and 145 age matched normal healthy controls. DNA was extracted from whole blood and genotyping was conducted using PCR-RFLP. rs1799794 showed significant association, where AA and AA+AG occurred at a significantly higher frequency in the cancer patients compared to the control group (OR: 28.1; 95% CI: 3.76-21.12; χ (2): 22.82; p < 0.0001). The G allele was protective and presented with a dominant model. The genotype and allele frequencies of rs861539 C>T and rs1799796 A>G did not show a significant difference when the results in the patients and controls were compared. However, the frequency of rs1799796 differed significantly in patients with different age of diagnosis, tumor grade, and ER and HER2 status. The wild type A allele occurred at a higher frequency in the ER- and HER2- group. Our results among Saudis suggest that some variations in XRCC3 may contribute to breast cancer susceptibility. In conclusion, the results obtained during this study suggest that rs1799794 in XRCC3 shows strong association with breast cancer development in Saudi females.

Association between the XRCC3 Thr241Met polymorphism and breast cancer risk: an updated meta-analysis of 36 case-control studies

BACKGROUND

The X-ray repair cross-complementing group 3 (XRCC3) is a highly suspected candidate gene for cancer susceptibility. Attention has been drawn upon associations of the XRCC3 Thr241Met polymorphism with breast cancer risk. However, the previous published findings remain controversial. Hence, we performed a meta-analysis to accurately evaluate any association between breast cancer and XRCC3 T241M (23, 812 cases and 25, 349 controls) in different inheritance models.

MATERIALS AND METHODS

PubMed and Web of Science databases were searched systematically until December 31, 2013 to obtain all the records evaluating the association between the XRCC3 Thr241Met polymorphism and breast cancer risk. Crude odds ratios (ORs) together with 95% confidence intervals (CIs) were used to assess the strength of associations.

RESULTS

When all eligible studies were pooled into the meta analysis of XRCC3 T241M polymorphism, a significantly increased breast cancer risk was observed in heterozygote comparison (OR=1.06, 95%CI=1.01-1.12). No significant associations were found in other models. In subgroup analysis, this polymorphism seemed to be associated with elevated breast risk in Asians. No publication bias was detected.

CONCLUSIONS

This meta-analysis suggests that the T241M polymorphism confers a weakly increased breast cancer risk. A study with the larger sample size is needed to further evaluate gene-gene and gene-environment interactions of the XRCC3 T241M polymorphism with breast cancer risk.

Association between the XRCC3 Thr241Met polymorphism and risk of colorectal cancer: a meta analysis of 5,193 cases and 6,645 controls

BACKGROUND

Many studies have reported associations of the X-ray repair cross-complementing group 3 (XRCC3) Thr241Met polymorphism with colorectal cancer (CRC) risk, but the results remained controversial. Hence, we performed the present meta-analysis with different inheritance models.

MATERIALS AND METHODS

We searched the PubMed and Google scholar databases for studies relating to associations between XRCC3 Thr241Met polymorphism and risk of CRC. 16 studies with 5,193 cases and 6,645 controls were finally included into the meta-analysis.

RESULTS

We found that the XRCC3 Thr241Met polymorphism was associated with increased CRC risk only under a dominant genetic model (CC+CT vs. TT: OR 0.575, 95%CI 0.498-1.665, p<0.001, Pheterogeneity=0.00, I2=83%). There was a significant association between XRCC3 Thr241Met polymorphism and CRC risk in Caucasian in the overall 8 studies under only in the heterozygote genetic model (CT vs. TT: OR=0.929, 95%CI=0.806-1.070, P=0.308, Pheterogeneity=0.002, I2=57%). Four studies evaluated the XRCC3 Thr241Met polymorphism and CRC risk in Asians. Two genetic models of the XRCC3 polymorphism were significantly correlated with increasing risk in Asians (dominant model: CC+CT vs. TT: OR= 0.609, 95%CI=411-0.902, P=0.013, Pheterogeneity=0.54, I2=0.00%; Allele model: C vs. T: OR=0.708, 95 %=CI 0.605-0.829, p=0.000, Pheterogeneity=0.000, I2=92%). The sensitivity analysis suggested stability of this meta-analysis and no publication bias was detected.

CONCLUSIONS

In conclusion, this meta-analysis indicates that XRCC3 Thr241Met shows an increased CRC risk, particularly in Asians rather than Caucasians.

Homologous Recombination Repair Polymorphisms and the Risk for Osteosarcoma

Background

DNA repair mechanisms are essential for maintaining genome stability, and genetic variability in DNA repair genes may contribute to cancer susceptibility. Our aim was to evaluate the influence of polymorphisms in the homologous recombination repair genes XRCC3, RAD51, and NBN on the risk for osteosarcoma.

Methods

In total, 79 osteosarcoma cases and 373 controls were genotyped for eight single nucleotide polymorphisms (SNPs) in XRCC3, RAD51, and NBN. Logistic regression was used to determine the association of these SNPs with risk for osteosarcoma.

Results

None of the investigated SNPs was associated with risk for osteosarcoma in the whole cohort of patients, however, in patients diagnosed before the age of thirty years XRCC3 rs861539 C>T and NBN rs1805794 G>C were associated with significantly decreased risk for osteosarcoma (P=0.047, OR=0.54, 95% CI=0.30–0.99 and P=0.036, OR=0.42, 95% CI=0.19–0.94, respectively). Moreover, in the carriers of a combination of polymorphic alleles in both SNPs risk for osteosarcoma was decreased even more significantly (P_trend=0.007). The risk for developing osteosarcoma was the lowest in patients with no wild-type alleles for both SNPs (P=0.039, OR=0.31, 95% CI=0.10–0.94).

Conclusions

Our results suggest that polymorphisms in homologous recombination repair genes might contribute to risk for osteosarcoma in patients diagnosed below the age of thirty years.

Polymorphisms in DNA repair genes XRCC1 and XRCC3, occupational exposure to arsenic and sunlight, and the risk of non-melanoma skin cancer in a European case-control study

X-ray repair cross-complementing group 1 (XRCC1) and group 3 (XRCC3) polymorphisms are relatively frequent in Caucasian populations and may have implications in skin cancer modulation. A few studies have evaluated their association with non-melanoma skin cancer (NMSC), but the results are inconsistent. In the current study, we aim to assess the impact of XRCC1 R399Q and XRCC3 T241M polymorphisms on the risk of NMSC associated with sunlight and arsenic exposure. Study participants consist of 618 new cases of NMSC and 527 hospital-based controls frequency matched on age, sex, and county of residence from Hungary, Romania, and Slovakia. Adjusted effects are estimated using multivariable logistic regression. The results indicate an increased risk of squamous cell carcinoma (SCC) for the homozygous variant genotype of XRCC1 R399Q (OR 2.53, 95% CI 1.14-5.65) and a protective effect against basal cell carcinoma (BCC) for the homozygous variant genotype of XRCC3 T241M (OR 0.61, 95% CI 0.41-0.92), compared with the respective homozygous common genotypes. Significant interactions are detected between XRCC3 T241M and sunlight exposure at work, and between XRCC3 T241M and exposure to arsenic in drinking water (p-value for interaction <0.10). In conclusion, the current study demonstrates that polymorphisms in XRCC genes may modify the associations between skin cancer risk and exposure to sunlight or arsenic. Given the high prevalence of genetic polymorphisms modifying the association between exposure to environmental carcinogens and NMSC, these results are of substantial relevance to public health.

NBN and XRCC3 genetic variants in childhood acute lymphoblastic leukaemia

Nibrin and DNA repair protein XRCC3 are involved in DNA double-strand break repair. We genotyped seven tagging SNPs in these genes (rs1805794, rs709816; rs1063054; rs7141928, rs1799794, rs861530, rs861539) with the aim to analyse their association with acute lymphoblastic leukaemia (ALL), a disease, that is characterised by elevated genetic instability. Study consisted of 460 paediatric ALL cases and 552 healthy controls. For selection of DNA sequence variants we employed SNP-tagging approach, incorporating the HAPMAP CEU reference panel data. We did not find association of analysed and tagged SNPs and derived haplotypes with the ALL risk thus did not confirm the hypothesis that analysed DNA recombination repair variants account for increased susceptibility to ALL.

XRCC3 C18067T polymorphism contributes a decreased risk to both basal cell carcinoma and squamous cell carcinoma: evidence from a meta-analysis

Background

The X-ray repair cross-complementing group 3 (XRCC3) in homologous recombination repair (HRR) pathway plays a very important role in DNA double-strand break repair (DSBR). Variations in the XRCC3 gene might lead to altered protein structure or function which may change DSBR efficiency and result in cancer. The XRCC3 C18067T polymorphism has been reported to be associated with skin cancer susceptibility, yet the results of these previous results have been inconsistent or controversial. To derive a more precise estimation of the association, we conducted a meta-analysis.

Methods

The quality of the studies was assessed according to a predefined scale. The association between the XRCC3 C18067T polymorphism and skin cancer risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs).

Results

Overall, no significant association was observed between XRCC3 C18067T polymorphism and skin cancer risk in any genetic model. Stratified analyses according to tumor type, significant association was found in the relationship between XRCC3 C18067T polymorphism and nonmelanoma skin cancer risk (homozygote comparison TT versus CC: OR = 0.74, 95%CI = 0.61–0.90, P = 0.003; recessive model TT versus TC/CC: OR = 0.81, 95%CI = 0.68–0.95, P = 0.01). Furthermore, significant association was also observed in XRCC3 C18067T polymorphism with both basal cell carcinoma risk (homozygote comparison TT versus CC: OR = 0.70, 95%CI = 0.53–0.92, P = 0.011; recessive model TT versus. TC/CC: OR = 0.74, 95%CI = 0.60–0.92, P = 0.007) and squamous cell carcinoma risk (heterozygote comparison TT versus .CC: OR = 0.81, 95%CI = 0.67–0.99, P = 0.04; dominant model TT/TC versus .CC: OR = 0.81, 95%CI = 0.68–0.98, P = 0.029).

Conclusion

The present meta-analysis demonstrates that XRCC3 C18067T polymorphism was not associated with risk of cutaneous melanoma but contributed a decreased risk to both basal cell carcinoma and squamous cell carcinoma.

Polymorphisms in human DNA repair genes and head and neck squamous cell carcinoma

Genetic polymorphisms in some DNA repair proteins are associated with a number of malignant transformations like head and neck squamous cell carcinoma (HNSCC). Xeroderma pigmentosum group D (XPD) and X-ray repair cross-complementing proteins 1 (XRCC1) and 3 (XRCC3) genes are involved in DNA repair and were found to be associated with HNSCC in numerous studies. To establish our overall understanding of possible relationships between DNA repair gene polymorphisms and development of HNSCC, we surveyed the literature on epidemiological studies that assessed potential associations with HNSCC risk in terms of gene-environment interactions, genotype-induced functional defects in enzyme activity and/or protein expression, and the influence of ethnic origin on these associations.We conclude that large, well-designed studies of common polymorphisms in DNA repair genes are needed. Such studies may benefit from analysis of multiple genes or polymorphisms and from the consideration of relevant exposures that may influence the likelihood of HNSCC when DNA repair capacity is reduced.

The influence of genetic polymorphisms in XRCC3 and ADH5 genes on the frequency of genotoxicity biomarkers in workers exposed to formaldehyde

The International Agency for Research on Cancer classified formaldehyde as carcinogenic to humans because there is "sufficient epidemiological evidence that it causes nasopharyngeal cancer in humans". Genes involved in DNA repair and maintenance of genome integrity are critically involved in protecting against mutations that lead to cancer and/or inherited genetic disease. Association studies have recently provided evidence for a link between DNA repair polymorphisms and micronucleus (MN) induction. We used the cytokinesis-block micronucleus (CBMN assay) in peripheral lymphocytes and MN test in buccal cells to investigate the effects of XRCC3 Thr241Met, ADH5 Val309Ile, and Asp353Glu polymorphisms on the frequency of genotoxicity biomarkers in individuals occupationally exposed to formaldehyde (n = 54) and unexposed workers (n = 82). XRCC3 participates in DNA double-strand break/recombination repair, while ADH5 is an important component of cellular metabolism for the elimination of formaldehyde. Exposed workers had significantly higher frequencies (P < 0.01) than controls for all genotoxicity biomarkers evaluated in this study. Moreover, there were significant associations between XRCC3 genotypes and nuclear buds, namely XRCC3 Met/Met (OR = 3.975, CI 1.053-14.998, P = 0.042) and XRCC3 Thr/Met (OR = 5.632, CI 1.673-18.961, P = 0.005) in comparison with XRCC3 Thr/Thr. ADH5 polymorphisms did not show significant effects. This study highlights the importance of integrating genotoxicity biomarkers and genetic polymorphisms in human biomonitoring studies.

The relationship between XRCC1 and XRCC3 gene polymorphisms and lung cancer risk in northeastern Chinese

Background

The prevalence of lung cancer in China will be the world's highest if allowed to proceed uncurbed. To unravel its genetic underpinnings, we sought to investigate the association of three well-characterized nonsynonymous polymorphisms in XRCC1 (Arg194Trp and Arg399Gln) and XRCC3 (Thr241Met) genes with lung cancer risk in northeastern Chinese.

Methodology/Principal Findings

This study was hospital-based in design, encompassing 684 patients with lung cancer and 604 cancer-free controls. Genotyping was performed using the PCR-LDR (ligase detection reactions) method. Data were analyzed by R language and multifactor dimensionality reduction (MDR) software. Single-locus analysis identified significance in genotype distributions of polymorphism Arg194Trp (P = 0.002) and Arg399Gln (P = 0.017), and in allele distributions of Thr241Met (P = 0.005). Carriers of 399Gln/Gln genotype conferred a 147% increased risk relative to the non-carriers (odds ratio (OR): 2.47; 95% confidence interval (95% CI): 1.48–4.13; P<0.001). For Thr241Met, significance persisted under allelic (OR = 1.63; 95% CI: 1.14–2.33; P = 0.005), additive (OR = 1.64; 95% CI: 1.16–2.32; P = 0.005) and dominant (OR = 1.67; 95% CI: 1.17–2.38; P = 0.004) models. However, common allele combinations were comparable in frequency between patients and controls. In interaction analysis, the overall best MDR model included Arg399Gln and Thr241Met polymorphisms, with a maximal testing accuracy of 63.18% and a maximal cross-validation consistency of 10 out of 10 (P = 0.0175).

Conclusions

Our study significantly demonstrated an independent and synergistic contribution of XRCC1 Arg399Gln and XRCC3 Thr241Met polymorphisms to lung cancer susceptibility in northeastern Chinese.

Polymorphisms in DNA repair genes and susceptibility to glioma in a chinese population

The excision repair cross-complementing rodent repair deficiency complementation group 1 (ERCC1), and X-ray repair cross-complementing group 1 (XRCC1) genes appear to protect mammalian cells from the harmful effects of ionizing radiation. We conducted a large case-control study to investigate the association of polymorphisms in ERCC1 C118T, ERCC1 C8092A, XRCC1 A194T, XRCC1 A194T, and XRCC3 C241T, with glioma risk in a Chinese population. Five single nucleotide polymorphisms (SNPs) were genotyped, using the MassARRAY IPLEX platform, in 443 glioma cases and 443 controls. Association analyses based on an χ² test and binary logistic regression were performed to determine the odds ratio (OR) and a 95% confidence interval (95% CI) for each SNP. For XRCC1 Arg194Trp, the variant genotype T/T was strongly associated with a lower risk of glioma cancer when compared with the wild type C/C (OR = 2.45, 95% CI = 1.43–4.45). Individuals carrying the XRCC1 399A allele had an increased risk of glioma (OR = 1.33, 95% CI = 1.02–1.64). The XRCC3 241T/T genotype was associated with a strong increased glioma risk (OR = 3.78, 95% CI = 1.86–9.06). Further analysis of the interactions of two susceptibility-associated SNPs, XRCC1 Arg194Trp and XRCC3 Thr241Met, showed that the combination of the XRCC1 194T and XRCC3 241T alleles brought a large increase in glioma risk (OR = 2.75, 95% CI = 1.54–4.04). XRCC1 Arg194Trp, XRCC1 Arg399Gln, and XRCC3 C241T, appear to be associated with susceptibility to glioma in a Chinese population.

Advances in the treatment of Basal cell carcinoma: Hedgehog inhibitors

Basal cell carcinoma (BCC) is the most common tumor of the skin and can result in significant morbidity as well as costs. The discovery of aberrant Hedgehog (HH) signaling in patients with genetic propensity to develop BCCs has resulted in a better understanding of the genetic abnormalities leading to the development of BCC. The current state of knowledge with regard to the genetics of BCC is discussed. Existing therapies are reviewed, in particular new targeted therapies to the HH signaling pathway that have resulted in a landmark breakthrough for patients with refractory BCC. Data from recent and ongoing trials are presented.

Genetic variability of Xrcc3 and Rad51 modulates the risk of head and neck cancer

A case-control study was conducted to analyze the possible associations between the head and neck cancer (HNC) risk and fourteen single nucleotide polymorphisms (SNPs) and haplotypes in Xrcc3 and Rad51 genes. This study involved 81 HNC cases and 111 healthy control subjects. A significant risk-increasing effect of rs3212057 (p.Arg94His) SNP in Xrcc3 (OR=6.6; p<0.01) was observed. On the other hand, risk-decreasing effect was found for rs5030789 (g.3997A>G) and rs1801321 (c.-60G>T) in 5' near gene and 5'UTR regions of Rad51, respectively (OR=0.3 and OR=0.2, p<0.05, respectively). Moreover, these effects were shown to be modulated by tobacco-smoking status and gene-gene interactions. Concluding, the genetic variability of Xrcc3 and/or Rad51 genes might be of relevance with respect to HNC risk.

Genetic polymorphisms in homologous recombination repair genes in healthy Slovenian population and their influence on DNA damage

Background

Homologous recombination (HR) repair is an important mechanism involved in repairing double-strand breaks in DNA and for maintaining genomic stability. Polymorphisms in genes coding for enzymes involved in this pathway may influence the capacity for DNA repair. The aim of this study was to select tag single nucleotide polymorphisms (SNPs) in specific genes involved in HR repair, to determine their allele frequencies in a healthy Slovenian population and their influence on DNA damage detected with comet assay.

Materials and methods

In total 373 individuals were genotyped for nine tag SNPs in three genes: XRCC3 722C>T, XRCC3 -316A>G, RAD51 -98G>C, RAD51 -61G>T, RAD51 1522T>G, NBS1 553G>C, NBS1 1197A>G, NBS1 37117C>T and NBS1 3474A>C using competitive allele-specific amplification (KASPar assay). Comet assay was performed in a subgroup of 26 individuals to determine the influence of selected SNPs on DNA damage.

Results

We observed that age significantly affected genotype frequencies distribution of XRCC3 -316A>G (P = 0.039) in healthy male blood donors. XRCC3 722C>T (P = 0.005), RAD51 -61G>T (P = 0.023) and NBS1 553G>C (P = 0.008) had a statistically significant influence on DNA damage.

Conclusions

XRCC3 722C>T, RAD51 -61G>T and NBS1 553G>C polymorphisms significantly affect the repair of damaged DNA and may be of clinical importance as they are common in Slovenian population.

Association of XRCC1, XRCC3, and NAT2 polymorphisms with the risk of oral submucous fibrosis among eastern Indian population

BACKGROUND

Arecanut and smokeless tobacco usage is a major cause for oral submucous fibrosis (OSF) and its subsequent development to oral squamous cell carcinoma in South-east Asian population. Polymorphisms at N-acetyltransferase 2 locus, coding for an enzyme catalyzing acetylation of aromatic amines, might cause DNA adduct formation because of improper acetylation of these polyaromatic hydrocarbons. DNA repair enzymes remove these adduct to prevent malignancy.

METHODS

In this hospital-based study, 100 controls and 88 OSF patients were genotyped at four polymorphic sites on NAT2 481 (C > T; silent), 590 (G > A; Arg197 > Gln), 803 (A > G; Lys268 > Arg), 857 (G > A; Gly286 > Glu) and two on XRCC1 18067 (C > T Arg 194 > Trp), 28152 (G > A Arg 399 > Gln), and one of XRCC3 26304 (C > T Thr 241 > Met) loci by PCR-RFLP to determine the risk of the disease.

RESULTS

Heterozygous XRCC3 codon 241 [OR 2.07 (1.05-4.06)], homozygous variant of NAT C481T [OR 2.81 (1.09-7.21)], and both heterozygous and homozygous variants of NAT codon 268 and 286 [OR 2.31 (1.20-4.45) and 4.98 (1.87-13.14), and 6.12 (2.75-13.62) and 2.65 (1.04-6.72)] individually influenced susceptibility to OSF in the population.

CONCLUSION

Gene-gene interaction analysis by multifactor dimensionality reduction (MDR) revealed that XRCC3 Thr 241 Met had the largest univariate effect followed by XRCC3 Thr 241 Met - NAT2 A857G in men that presents a highly synergistic interaction as one of the potential combinations of single nucleotide polymorphisms (SNPs) to increase the risk of OSF in men if exposed to arecanut or smokeless tobacco usage. These observations can speculate the impact of the studied SNPs on the etiology of OSF.

Genetic biomonitoring of inhabitants exposed to uranium in the north region of Brazil

Aiming to assess the susceptibility of populations in the Brazilian Amazon region to ionizing radiation emitted from uranium, mutations frequencies in the DNA repair genes XRCC1 and XRCC3 and in the metabolic gene GSTM1 were evaluated. The XRCC1 allele frequencies for the 194Trp polymorphism in the municipalities of Monte Alegre, Prainha and Alenquer were, respectively, 0.12, 0.13 and 0.07, and for 399Gln polymorphism they were, respectively, 0.28, 0.30 and 0.32. Frequencies for GSTM1 gene deletion homozygotes were, respectively, 0.36, 0.31 and 0.40 for all municipalities. These frequencies are comparable to those described for Brazilian individuals from other regions of the country. Also, allele frequencies of XRCC3 241Met polymorphism of the Monte Alegre and Alenquer populations were 0.28 and 0.33, respectively. In conclusion, frequencies of important polymorphic features of cellular DNA repair and metabolic apparatus in the populations studied do not differ from those of populations in other regions of Brazil.

Basal cell carcinoma: from the molecular understanding of the pathogenesis to targeted therapy of progressive disease

Due to intensified research over the past decade, the Hedgehog (HH) pathway has been identified as a pivotal defect implicated in roughly 25% of all cancers. As one of the most frequent cancer worldwide, the development of Basal cell carcinoma (BCC) due to activation of the HH pathway has been convincingly demonstrated. Thus the discovery of this central tumor-promoting signalling pathway has not only revolutionized the understanding of BCC carcinogenesis but has also enabled the development of a completely novel therapeutic approach. Targeting just a few of several potential mutations, HH inhibitors such as GDC-0449 achieved already the first promising results in metastatic or locally advanced BCC. This paper summarizes the current understanding of BCC carcinogenesis and describes the current “mechanism-based” therapeutic strategies.

Precancerous and non-cancer disease endpoints of chronic arsenic exposure: the level of chromosomal damage and XRCC3 T241M polymorphism

Genetic variants are expected to play an important role in arsenic susceptibility. Our previous study revealed deficient DNA repair capacity to be a susceptibility factor for arsenicism. T241M polymorphism in XRCC3 (a homologous recombination repair pathway gene) is widely studied for its association with several cancers. We have investigated the association of XRCC3 T241M polymorphism with arsenic-induced precancerous and non-cancer disease outcomes. The present study evaluated the association of T241M polymorphism with arsenic-induced skin lesions, peripheral neuropathy (neurodegenerative changes), conjunctivitis and other ocular diseases. A case-control study was conducted in West Bengal, India, involving 206 cases with arsenic-induced skin lesions and 215 controls without arsenic-induced skin lesions having similar arsenic exposure. XRCC3 T241M polymorphism was determined using conventional PCR-sequencing method. Chromosomal aberration assay, arsenic-induced neuropathy and ocular diseases were also evaluated. The data revealed that presence of at least one Met allele (Met/Met or Thr/Met) was protective towards development of arsenic-induced skin lesions [OR=0.45, 95% CI: 0.30-0.67], peripheral neuropathy [OR=0.49; 95%CI: 0.30-0.82] and conjunctivitis [OR=0.60; 95%CI: 0.40-0.92]. A significant correlation was also observed between protective genotype and decreased frequency of chromosomal aberrations. Thus the results indicate the protective role of Met allele against the arsenic-induced skin lesions, chromosomal instability, peripheral neuropathy and conjunctivitis.

Basal cell carcinoma and the carcinogenic role of aberrant Hedgehog signaling

Basal cell carcinoma (BCC) is the most frequent cancer in the white population and its incidence appears to be increasing worldwide. While the majority of BCCs arise sporadically, many cases are attributable to basal cell nevus syndrome, or Gorlin syndrome, an autosomal dominantly inherited disorder characterized by the occurrence of multiple BCCs and by extracutaneous tumors. Genetic studies on patients with basal cell nevus syndrome indicate deregulation of the Hedgehog (Hh) pathway in epidermal keratinocytes as the primary event in the pathogenesis of BCC. This article summarizes the recent progress in understanding Hh-dependent BCC tumorigenesis, as well as evidence for deregulation of other molecular pathways, primarily the Wnt developmental pathway. Understanding the molecular genetics of BCC development has provided new opportunities for molecular therapy of this cancer by targeting Hh and other signaling pathways.

XRCC3 Thr241Met polymorphism with lung cancer and bladder cancer: a meta-analysis

Several studies have investigated the associations between X-ray repair cross-complementing group 3 (XRCC3) Thr241Met polymorphism and the susceptibility to lung cancer and bladder cancer, but results have been inconclusive. In order to derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 22 case control studies, including 2976 cases and 4495 controls for lung cancer, and 3445 cases and 4599 controls for bladder cancer, met the inclusion criteria and were selected. Overall, there was no evidence showing a significant association between XRCC3 Thr241Met polymorphism and lung cancer risk. Furthermore, the results for bladder cancer showed that significant decreased risk was found for the additive model (odds ratio [OR] = 0.959, 95% confidence interval [CI], 0.924-0.996) and dominant model (OR = 0.982, 95% CI, 0.963-1.000) but not for the recessive model (OR = 0.958, 95% CI, 0.905-1.014). In summary, our meta-analysis indicates that XRCC3 Thr241Met polymorphism may be weakly associated with the risk of bladder cancer. (Cancer Sci 2010).

Variants in DNA double-strand break repair genes and risk of familial breast cancer in a South American population

The double-strand break (DSB) DNA repair pathway has been implicated in breast cancer (BC). RAD51 and its paralogs XRCC3 and RAD51D play an important role in the repair of DSB through homologous recombination (HR). Some polymorphisms including XRCC3-Thr241Met, RAD51-135G>C, and RAD51D-E233G have been found to confer increased BC susceptibility. In order to detect novel mutations that may contribute to BC susceptibility, 150 patients belonging to 150 Chilean BRCA1/2-negative families were screened for mutations in XRCC3. No mutations were detected in the XRCC3 gene. In addition, using a case-control design we studied the XRCC3-Thr241Met, and RAD51D-E233G polymorphisms in 267 BC cases and 500 controls to evaluate their possible association with BC susceptibility. The XRCC3 Met/Met genotype was associated with an increased BC risk (P = 0.003, OR = 2.44 [95%CI 1.34-4.43]). We did not find an association between E233G polymorphism and BC risk. We also analyzed the effect of combined genotypes among RAD51-135G>C, Thr241Met, and E233G polymorphisms on BC risk. No interaction was observed between Thr241Met and 135G>C. The combined genotype Thr/Met-E/G was associated with an increased BC risk among women who (a) have a family history of BC, (b) are BRCA1/2-negative, and (c) were <50 years at onset (n = 195) (P = 0.037, OR = 10.5 [95%CI 1.16-94.5]). Our results suggested that the variability of the DNA HR repair genes XRCC3 and RAD51D may play a role in BC risk, but this role may be underlined by a mutual interaction between these genes. These findings should be confirmed in other populations.

Genetic variations as cancer prognostic markers: review and update

Cancer molecular epidemiology traditionally studies the relationship between genetic variations and cancer risk. However, recent studies have also focused on disease outcomes. The application and design of disease outcome studies have been an extension of disease risk assessment. Yet there are a number of unique considerations important in outcome assessments. We review how genetic approaches used for disease susceptibility, such as candidate gene and genome-wide association study (GWAS) approaches, can be adapted carefully to systematically identify cancer prognostic and predictive alleles. We discuss the interrelatedness among the disease susceptibility, treatment response, and prognosis at the genetic level and focus on how the emerging technologies and approaches can uniquely benefit the genetic prognosis studies.

Do DNA repair genes OGG1, XRCC3 and XRCC7 have an impact on susceptibility to bladder cancer in the North Indian population?

OBJECTIVE

Polymorphisms in DNA repair genes may be associated with altered DNA repair capacity, thereby influencing an individual's susceptibility to smoking-related cancers such as bladder cancer. Therefore, we sought to examine the correlation between single nucleotide polymorphisms in DNA repair genes and bladder cancer.

METHODOLOGY

We undertook a case-control study of 212 urothelial bladder cancer (UBC) cases and 250 controls to investigate the association between OGG1 (C1245G rs1052133), XRCC3 (C18067T, rs861539) and XRCC7 (G6721T, rs7003908) polymorphisms and bladder cancer susceptibility by PCR-RFLP and the ARMS method. We also investigated gene-environment interactions.

RESULTS

The OGG1 GG genotype was associated with an elevated risk of urothelial bladder cancer (UBC) (OR, 2.10; p, 0.028). XRCC7 + 6721 GG was also associated with increased susceptibility to UBC (OR, 4.45; p, 0.001). In a recessive model, the OGG1 GG genotype showed an increased risk of TaG(2,3) + T1G(1-3) tumors. Additionally, the OGG1 GG genotype in non-smokers represented a 2.46-fold greater risk (OR, 2.46; p, 0.035) in bladder cancer patients. Subsequent analysis demonstrated more pronounced association of XRCC7 with smokers (OR, 4.39; p, 0.001). XRCC7 also showed increased association with TaG(2,3) + T1G(1-3) tumors and muscle invasive tumors (OR, 3.16; p, 0.001 and OR, 4.24; p, 0.001, respectively). Multiple Cox regression analysis in non-muscle invasive bladder tumor (NMIBT) patients demonstrated an association of the OGG1 GG polymorphism with a high risk of recurrence in patients on cystoscopic surveillance (HR, 4.04; p, 0.013). Subsequently, shorter recurrence-free survival (log rank p, 0.024; CC/GG, 42/24) was observed.

CONCLUSION

Our data suggest association of a variant (GG) genotype of OGG1 with increased UBC susceptibility and a high risk of tumor recurrence in NMIBT patients on cystoscopic surveillance. XRCC7 G allele carriers (TG+GG) are also at an elevated risk for susceptibility to UBC as evidenced by a high odds ratio throughout the analysis.

XRCC3 Thr241Met polymorphism and breast cancer risk: a meta-analysis

XRCC3 (X-ray repair complementing defective repair in Chinese hamster cells 3) is a member of the RecA/Rad51-related protein family that participates in homologous recombination, maintaining chromosome stability and participating in DNA repair. Attention has been drawn upon the association of XRCC3 Thr241Met polymorphism with breast cancer risk. The present meta-analysis aims to examine whether XRCC3 Thr241Met polymorphism status is associated with breast cancer risk. Apart from the overall meta-analysis, separate analyses were performed on Chinese and non-Chinese populations, in order to investigate race-specific effects. Eligible articles were identified by a search of MEDLINE bibliographical database for the period up to August 2009. Twenty case-control studies on non-Chinese subjects (19,575 cases and 21,125 controls) and three case-control studies on Chinese subjects (1,216 cases and 1,112 controls) were eligible. Pooled odds ratios (OR) were appropriately derived from fixed-effects or random-effects models. At the overall analysis, the T allele was associated with elevated breast cancer risk mainly following a recessive model (pooled OR = 1.064, 95% CI: 1.007-1.124, fixed effects), given that the effect was more pronounced in homozygous carriers (pooled OR = 1.073, 95% CI: 1.010-1.140, fixed effects). The association seemed confined in non-Chinese populations, once again following a recessive model (pooled OR = 1.072, 95% CI: 1.014-1.133, fixed effects). Concerning Chinese populations, no consistent results were demonstrated. In conclusion, the XRCC3 Thr241Met T allele seems associated with elevated breast cancer risk in non-Chinese subjects. The need for additional studies on Chinese populations seems warranted.

Genetic polymorphisms in XRCC1, OGG1, APE1 and XRCC3 DNA repair genes, ionizing radiation exposure and chromosomal DNA damage in interventional cardiologists

Interventional cardiologists working in high-volume cardiac catheterization laboratory are exposed to significant occupational radiation risks. Common single-nucleotide polymorphisms (SNPs) in DNA repair genes are thought to modify the effects of low-dose radiation exposure on DNA damage, the main initiating event in the development of cancer and hereditary disease. The aim of this study was to determine the relationship between XRCC1 (Arg194Trp and Arg399Gln), OGG1 (Ser326Cys), APE1 (Asp148Glu) and XRCC3 (Thr241Met) SNPs and chromosomal DNA damage. We enrolled 77 subjects: 40 interventional cardiologists (27 male, 41.3+/-9.4 years and 13 female, 37.8+/-8.4 years) and 37 clinical cardiologists (26 male, 39.4+/-9.5 years and 11 female, 35.0+/-9.8 years) without radiation exposure as the control group. Micronucleus (MN) assay was performed as biomarker of chromosomal DNA damage and an early predictor of cancer. MN frequency was significantly higher in interventional cardiologists than in clinical physicians (19.7+/-7.8 per thousand vs. 13.5+/-6.3 per thousand, p=0.0003). Within the exposed group, individuals carrying a XRCC3 Met241 allele had higher frequency than homozygous XRCC3 Thr241 (21.2+/-7.8 per thousand vs. 16.6+/-7.1 per thousand, p=0.03). Individuals with two or more risk alleles showed a higher MN frequency when compared to subjects with one or no risk allele (18.4+/-6.6 per thousand vs. 14.4+/-6.1 per thousand, p=0.02). An interactive effect was found between smoking, exposure >10 years and the presence of the two or more risk alleles on the MN frequency (F=6.3, p=0.02). XRCC3 241Met alleles, particularly in combination with multiple risk alleles of DNA repair genes, contribute to chromosomal DNA damage levels in interventional cardiologists.

Association between polymorphisms in RMI1, TOP3A, and BLM and risk of cancer, a case-control study

Background

Mutations altering BLM function are associated with highly elevated cancer susceptibility (Bloom syndrome). Thus, genetic variants of BLM and proteins that form complexes with BLM, such as TOP3A and RMI1, might affect cancer risk as well.

Methods

In this study we have studied 26 tagged single nucleotide polymorphisms (tagSNPs) in RMI1, TOP3A, and BLM and their associations with cancer risk in acute myeloid leukemia/myelodysplatic syndromes (AML/MDS; N = 152), malignant melanoma (N = 170), and bladder cancer (N = 61). Two population-based control groups were used (N = 119 and N = 156).

Results

Based on consistency in effect estimates for the three cancer forms and similar allelic frequencies of the variant alleles in the control groups, two SNPs in TOP3A (rs1563634 and rs12945597) and two SNPs in BLM (rs401549 and rs2532105) were selected for analysis in breast cancer cases (N = 200) and a control group recruited from spouses of cancer patients (N = 131). The rs12945597 in TOP3A and rs2532105 in BLM showed increased risk for breast cancer. We then combined all cases (N = 584) and controls (N = 406) respectively and found significantly increased risk for variant carriers of rs1563634 A/G (AG carriers OR = 1.7 [95%CI 1.1–2.6], AA carriers OR = 1.8 [1.2–2.8]), rs12945597 G/A (GA carriers OR = 1.5 [1.1–1.9], AA carriers OR = 1.6 [1.0–2.5]), and rs2532105 C/T (CT+TT carriers OR = 1.8 [1.4–2.5]). Gene-gene interaction analysis suggested an additive effect of carrying more than one risk allele. For the variants of TOP3A, the risk increment was more pronounced for older carriers.

Conclusion

These results further support a role of low-penetrance genes involved in BLM-associated homologous recombination for cancer risk.