XRCC3haplotypes and risk of gliomas in a Chinese population: A hospital-based case-control study

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.

The relationship between polymorphisms of XRCC5 genes with astrocytoma prognosis in the Han Chinese population

BACKGROUND

Gliomas are highly malignant with a poor prognosis. Studies have reported that DNA repair genes influence risk for glioma, but its relationship with prognosis is unclear. In this study, we want to explore the relationship between DNA repair genes (XRCC3, XRCC4 and XRCC5) and prognosis of astrocytoma in the Chinese Han population.

MATERIALS AND METHODS

160 astrocytoma cases were recruited in our study. Survival probabilities were estimated by using Kaplan-Meier analysis, and significant differences were analyzed by using the log-rank test. Cox proportional hazards models were used to analyze the associations between genotypes with astrocytoma survival. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using multivariable models. All tests were two-sided and p < 0.05 was considered to be significant.

RESULTS

The SNP (rs9288516) in XRCC5 (HR: 1.69, 95%CI: 1.04 - 2.77, p = 0.049), surgical approach (HR: 0.61, 95%CI: 0.43 - 0.88, p = 0.003) and chemotherapy (HR: 0.71, 95%CI: 0.50 - 0.99, p = 0.029) were associated with astrocytoma prognosis. Further, the "A/A" genotype of rs9288516 in XRCC5 (HR: 1.67, 95%CI: 1.02 - 2.72, p = 0.042) had significantly outcomes after adjusting for potential confounders, patients with poor tumor differentiation and the coexistence of the unfavorable genotypes.

CONCLUSION

These results suggest that polymorphisms of XRCC5 play an important role in astrocytoma prognosis in the Chinese Han population which could be used in the determination of astrocytoma prognosis in clinical researches.

Polymorphisms in DNA Repair Gene and Susceptibility to Glioma: A Systematic Review and Meta-Analysis Based on 33 Studies with 15 SNPs in 9 Genes

At present, many publications have evaluated the correlation between the DNA repair gene polymorphisms and glioma susceptibility. However, the results remain inconclusive. The aim of this research is to exhaustively assess the association of genetic polymorphisms in DNA repair genes with glioma risk in human. Meta-analysis method was conducted, and 33 studies with 15 SNPs in 9 genes were included (12553 glioma cases and 17178 controls). Correlation strength was evaluated by odds ratio with a 95 % confidence interval. Rs1799782 T allele and rs25487A allele might bring about higher risk of glioma in Asian population. Rs1805377 G allele was an increased risk genetic factor of glioma. Asian carried with rs3212986 A allele was more likely to have glioma. Rs1800067 G allele was a risk factor of developing glioma. Carriers with rs12917 CC genotype in MGMT gene had higher risk of glioma in Caucasian than other non-CC genotype carriers. Carriers with rs1136410 T allele in PARP1 gene could more likely to develop glioma in Caucasian. This meta-analysis suggests that glioma susceptibility is associated with rs1799782 and rs25487 of X-ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1), rs1805377 of XRCC4, rs1800067 of excision repair cross-complementing rodent repair deficiency complementation group 4 (ERCC4) and rs3212986 of ERCC1 in Asian population, and rs12917 of O-6-methylguanine-DNA methyltransferase (MGMT) and rs1136410 of poly(ADP-ribose) polymerase 1 (PARP1) in Caucasian population.

A Comprehensive Meta-analysis of Genetic Associations Between Key Polymorphic Loci in DNA Repair Genes and Glioma Risk

Genetic variants found in DNA repair genes (ERCC1, rs3212986; ERCC2, rs13181; ERCC4, rs1800067; ERCC5, rs17655; XRCC1, rs1799782, rs25487, rs25489; XRCC3, rs861539) have been reported to have an ambivalent association with the development of glioma. In the present study, a meta-analysis was conducted to confirm the relationship, taking heterogeneity of population into consideration. We analyzed 21 articles of 6 genes along with 8 single nucleotide polymorphisms (SNPs) (24,078 cases and 30,926 healthy individuals), which assessed the relationship between nucleotide excision, base excision, double-strand break repair gene, and the development of glioma under five models. All statistical analysis was implemented by the software of R 3.2.1, and the relationships between key polymorphic loci in DNA repair genes and glioma were quantified by the pooled odds ratio (OR) and 95 % confidential intervals. Overall, the synthesized evidence demonstrated that the SNP of rs13181 and rs1799782 significantly increased the risk of glioma whereas SNP of rs1800067 were significantly associated with a decrease in the risk of glioma. Additionally, subgroup analyses of 8 SNPs by ethnicity indicated that the mutation of rs13181, rs1800067 were apparently protective factors of glioma among Asians, while the mutation of rs13181 was a risk factors of glioma in Caucasians. Furthermore, the mutation of rs1799782 significantly raises the risk of glioma for Asian. Our study suggested that rs13181*C and rs1799782*A are risk alleles for glioma; rs1800067*A are beneficial alleles for decreased susceptibility to glioma. Future studies with large sample size and other races are strongly recommended to confirm the results from this study.

Genetic variations in the homologous recombination repair pathway genes modify risk of glioma

Accumulative epidemiological evidence suggests that single nucleotide polymorphisms (SNPs) in genes involved in homologous recombination (HR) DNA repair pathway play an important role in glioma susceptibility. However, the effects of such SNPs on glioma risk remain unclear. We used a used a candidate pathway-based approach to elucidate the relationship between glioma risk and 12 putative functional SNPs in genes involved in the HR pathway. Genotyping was conducted on 771 histologically-confirmed glioma patients and 752 cancer-free controls from the Chinese Han population. Odds ratios (OR) were calculated both for each SNP individually and for grouped analyses, examining the effects of the numbers of adverse alleles on glioma risk, and evaluated their potential gene-gene interactions using the multifactor dimensionality reduction (MDR). In the single-locus analysis, two variants, the NBS1 rs1805794 (OR 1.42, 95% CI 1.15-1.76, P = 0.001), and RAD54L rs1048771 (OR 1.61, 95% CI 1.17-2.22, P = 0.002) were significantly associated with glioma risk. When we examined the joint effects of the risk-conferring alleles of these three SNPs, we found a significant trend indicating that the risk increases as the number of adverse alleles increase (P = 0.005). Moreover, the MDR analysis suggested a significant three-locus interaction model involving NBS1 rs1805794, MRE11 rs10831234, and ATM rs227062. These results suggested that these variants of the genes involved in the HR pathway may contribute to glioma susceptibility.

Association between x-ray repair cross-complementing group 3 (XRCC3) genetic polymorphisms and papillary thyroid cancer susceptibility in a Chinese Han population

Papillary thyroid cancer (PTC) is a predominant type of thyroid cancer. Ionizing radiation is the only well-established risk factor and may result in double-strand breaks. The x-ray repair cross-complementing group 3 (XRCC3) gene plays a vital role in DNA repair through homologous recombination. We aimed at investigating the association between XRCC3 genetic polymorphisms and PTC susceptibility. Eighty-three PTC patients and 367 controls in a Chinese population were enrolled in the study. Tag single-nucleotide polymorphisms (SNPs) were identified by HaploView 4.2 software. Genomic DNAs were isolated from peripheral blood samples by using TaqMan Blood DNA kits. The genotyping of XRCC3 SNPs was performed by TaqMan SNPs genotyping assay. Odds ratios (ORs) and corresponding 95 % confidence intervals (CIs) were calculated to evaluate the association between XRCC3 SNPs and PTC susceptibility. The statistical analyses were conducted by using SPSS 13.0 software. Four tag-SNPs were initially identified by HaploView 4.2 software. Only one SNP (rs861539) was shown to be significantly associated with increased risk of PTC. There was a significant difference in smoking and drinking status between PTC cases and controls. And the stratified analysis suggested that the polymorphisms of rs861539 in XRCC3 were correlated with PTC risk in the four subgroups of smokers (ex-smokers included), non-smokers, drinkers (ex-drinkers included), and non-drinkers. The meta-analysis showed that only two studies reported a significant association between XRCC3 polymorphisms and PTC risk. In this study, we find a significant association between rs861539 polymorphisms and PTC susceptibility. However, there were inconsistent results in previous published studies. Therefore, further studies in a large population are required to gain insights into the PTC risk conferred by XRCC3 SNPs.

Association of EFEMP1 gene polymorphisms with the risk of glioma: A hospital-based case-control study in a Chinese Han population

BACKGROUND

EGF-containing fibulin-like extracellular matrix protein1 (EFEMP1) gene was relative with the formation and development of tumors and had an anti-angiogenic function. Recently, many studies investigating the function of EFEMP1 gene, including its roles in prostate cancer and glioma, have been reported. EFEMP1 suppressed glioma growth by modulating EGFR and AKT signaling pathway or promoted growth through the regulation of Notch pathway were identified. However, the susceptibility of EFEMP1and glioma has not been well studied to date. Here, the authors were aimed to investigate whether the single nucleotide polymorphisms (SNPs) of EFEMP1 were associated with glioma susceptibility.

METHODS

The authors genotyped 14 common tagging SNPs of EFEMP1 gene via the Sequenom Mass ARRYiPLEX platform and assessed their association with glioma risk in a hospital-based case-control study in a Chinese Han population (979 cases and 1007 controls).

RESULTS

Four SNPs were significant associated with glioma risk (rs1346787, P=0.004, adjusted OR=1.49; rs3791679, P=0.014, adjusted OR=1.27; rs1346786, P=0.002, adjusted OR=1.41; rs3791675, P=0.011, adjusted OR=1.27). In further stratified analysis, all the significant SNPs except rs1346787 were associated with both low-grade gliomas and glioblastoma (GBM). In haplotype analysis, 4 haplotype blocks were identified and 2 of them were revealed significant associated with glioma, the haplotype "AA" (adjusted OR=1.44, P=0.005) in block 1 and haplotype "GG" (adjusted OR=1.65, P=0.0004) in block 2 had a 44% and 65% increased glioma risk respectively, compared with corresponding non-carriers. The results of haplotype analysis were significantly consistent with the single-locus analysis.

CONCLUSIONS

The authors' results suggested that common genetic variants in EFEMP1 gene were associated with glioma and contributed to glioma susceptibility, which might help to reveal the mechanism of gliomas and provide new insight for the diagnosis and treatment.

Genetic variants in N-myc (and STAT) interactor and susceptibility to glioma in a Chinese Han population

Glioma is one of the most common and lethal brain tumors. N-myc (and STAT) interactor (NMI) gene has been reported in tumorigenesis, and our previous study further showed its implication in glioma progression. To elucidate its involvement in the etiology of glioma, we conducted a case-control study of 875 patients and 1040 controls in a Chinese Han population by genotyping 7 representative single nucleotide polymorphisms (SNPs) in NMI. Allele and genotype frequency distribution of five loci (rs2278089, rs2194492, rs6734376, rs3854012, and rs11730) were significantly different between the cases and controls. Unconditional logistic regression showed that the variant genotypes of rs2278089 [adjusted odds ratio (OR) = 1.57, P = 4.23 × 10(-6)], rs2194492 (adjusted OR = 1.49, P = 1.20 × 10(-4)), and rs6734376 (adjusted OR = 0.06, P = 8.65 × 10(-13)) significantly affected glioma risk compared with the major homozygotes, while the minor homozygotes of rs3854012 (adjusted OR = 0.54, P = 4.64 × 10(-6)) and rs11730 (adjusted OR = 0.60, P = 1.50 × 10(-4)) showed significant protective effects. Further stratified analyses indicated that these associations remained significant in subgroups of low-grade glioma (LGG) and high-grade glioma (HGG). Additionally, haplotype and diplotype analyses showed consistent results. The Bonferroni correction was applied for all these analyses. Moreover, luciferase reporter gene assays revealed enhanced promoter activity of the C risk allele of rs2194492 in several cell lines compared with the G major allele, suggesting its potential function in transcriptional activation of NMI. Taken together, these results revealed that NMI polymorphisms may contribute to genetic susceptibility to glioma.

The XRCC3 Thr241Met polymorphism influences glioma risk - a meta-analysis

BACKGROUND

Findings from previous published studies regarding the association of the XRCC3 Thr241Met polymorphism with glioma susceptibility have often been conflicting. Therefore, a meta-analysis including all available publications was carried out to make a more precise estimation of the potential relationship.

METHODS

By searching the electronic databases of Pubmed and Embase (up to April 1st, 2013), a total of nine case-control studies with 3,752 cases and 4,849 controls could be identified for inclusion in the current meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the strength of the association.

RESULTS

This meta-analysis showed the XRCC3 Thr241Met polymorphism to be significantly associated with decreased glioma risk in the allelic model (Met allele vs. Thr allele: OR= 0.708, 95%CI= 0.631-0.795). Moreover, we also observed a statistically significant association between the XRCC3 Thr241Met polymorphism and reduced glioma risk in analyses stratified by ethnicity (Asian) and source of controls (hospital based) in the allelic model.

CONCLUSIONS

Current evidence suggests that the XRCC3 Thr241Met polymorphism may be a risk factor for glioma development, especially in Asians.

Association of leukocyte mitochondrial DNA content with glioma risk: evidence from a Chinese case-control study

Background

Increasing evidence suggests that alterations in mitochondrial DNA (mtDNA) content may be implicated in the tumorigenesis of several malignancies. However, the association between mtDNA content in peripheral blood lymphocytes (PBLs) and glioma risk has not been investigated.

Methods

Real-time PCR was used to examine the mtDNA content in PBLs of 414 glioma patients and 414 matched controls in a hospital-based case–control study. The association between mtDNA content and glioma risk was evaluated using an unconditional multivariate logistic regression model.

Results

We found that glioma patients exhibited a significantly higher median mtDNA content than healthy controls (0.99 vs. 0.71, P < 0.001). Unconditional multivariate logistic regression analysis adjusting for age, gender, smoking status, and family cancer history showed that there was an S-shaped association between mtDNA content and glioma risk. Higher mtDNA content was significantly associated with an elevated risk of glioma. Compared with the first quartile, the odds ratio (95% confidence interval) for subjects in the second, third, and fourth quartiles of mtDNA content were 0.90 (0.52-1.53), 3.38 (2.15-5.31), and 5.81 (3.74-9.03), respectively (P for nonlinearity = 0.009). Stratified analysis showed that the association between mtDNA content and glioma risk was not modulated by major host characteristics.

Conclusions

Our findings demonstrate for the first time that a higher mtDNA content in PBLs is associated with an elevated risk of glioma, which warrants further investigation in larger populations.

Association of XRCC3 Thr241Met polymorphisms and gliomas risk: evidence from a meta-analysis

The relationship between the X-ray repair cross-complementing group 3 (XRCC3) Thr241Met polymorphism and gliomas remains inclusive or controversial. For better understanding of the effect of XRCC3 Thr241Met polymorphism on glioma risk, a meta-analysis was performed. All eligible studies were identified through a search of PubMed, Elsevier Science Direct, Excerpta Medica Database (Embase) and Chinese Biomedical Literature Database (CBM) before May 2013. The association between the XRCC3 Thr241Met polymorphism and gliomas risk was conducted by odds ratios (ORs) and 95% confidence intervals (95% CIs). A total of nine case-control studies including 3,533 cases and 4,696 controls were eventually collected. Overall, we found that XRCC3 Thr241Met polymorphism was significantly associated with the risk of gliomas (T vs. C: OR=1.10, 95%CI=1.01-1.20, P=0.034; TT vs. CC: OR=1.30, 95%CI=1.03-1.65, P=0.027; TT vs.

TC/CC

OR=1.29, 95%CI=1.01-1.64, P=0.039). In the subgroup analysis based on ethnicity, the significant association was found in Asian under four models (T vs. C: OR=1.17, 95%CI=1.07-1.28, P=0.00; TT vs. CC: OR=1.79, 95%CI=1.36- 2.36, P=0.00; TT vs.

TC/CC

OR=1.75, 95%CI=1.32-2.32, P=0.00; TT/TC vs. CC: OR=1.11,95% CI=1.02-1.20). This meta-analysis suggested that the XRCC3 Thr241Met polymorphism is a risk factor for gliomas, especially for Asians. Considering the limited sample size and ethnicities included in the meta-analysis, further large scale and well-designed studies are needed to confirm our results.

Association between DNA repair gene polymorphisms and risk of glioma: a systematic review and meta-analysis

BACKGROUND

Association studies of germline DNA repair single nucleotide polymorphisms (SNPs) and glioma risk have yielded inconclusive results. We therefore performed a systematic review and meta-analysis of studies investigating this association.

METHODS

We identified 27 eligible studies investigating 105 SNPs in 42 DNA repair genes. Of these, 10 SNPs in 7 genes were analyzed in at least 4 studies and were therefore included in our meta-analysis. The meta-analysis was performed for homozygote comparison, heterozygote comparison, and dominant and recessive models by applying a fixed- or random-effects model. The funnel and forest plots were created using RevMan software.

RESULTS

We found that SNPs rs3212986 (odds ratio [OR] = 1.35 (1.08-1.68), P = .008), rs13181 (OR = 1.18 (1.06-1.31), P = .002), and rs25487 (OR = 1.12 (1.03-1.22), P = .007) in DNA repair genes ERCC1, ERCC2 (XPD), and XRCC1 may increase the risk of glioma, while polymorphisms rs1136410 (OR = 0.78 (0.68-0.89), P = .0004) and rs12917 (OR = 0.84 (0.73-0.96), P = .01) in PARP1(ADPRT) and MGMT are associated with decreased susceptibility to glioma. No evidence of significant associations between ERCC2 rs1799793, OGG1 rs1052133, XRCC1 rs25489, XRCC1 rs1799782, or XRCC3 rs861539 and risk of glioma was observed.

CONCLUSION

This study provides evidence that DNA repair genes ERCC1, ERCC2, and XRCC1 might be low-penetrance glioma-risk genes, while MGMT and PARP1 polymorphisms may confer protection against glioma.

Association between leukocyte telomere length and glioma risk: a case-control study

BACKGROUND

Compelling epidemiological evidence indicates that alterations of telomere length are associated with risks of many malignancies in a tumor-specific manner, such as lung cancer, breast cancer, and non-Hodgkin's lymphoma. However, the association between leukocyte telomere length and glioma risk has not been investigated.

METHODS

Relative telomere length (RTL) of peripheral blood leukocytes from 467 glioma patients and 467 healthy controls, matched by age and sex, was measured using the real-time PCR-based method in a case-control study. An unconditional multivariate logistic regression model was applied to estimate the association between RTL and glioma risk.

RESULTS

Glioma patients showed notably longer RTL than controls (median, 0.555 vs 0.444; P > .04). RTL was negatively correlated with age in both cases (ρ = -0.430; P < .001) and controls (ρ = -0.388; P < .001). After adjusting for age, sex, smoking status and family history of cancer, multivariate logistic regression analysis showed that there was a U-shaped association between RTL and glioma risk (P for nonlinearity <.001). Compared with individuals in the second tertile of RTL, the odds ratios (95% CI) for participants in the first and third tertiles were 2.16 (range, 1.52-3.09) and 3.51 (range, 2.45-5.00), respectively. Stratified analysis showed that the association between RTL and glioma risk was not modulated by major host characteristics.

CONCLUSIONS

Our study demonstrates for the first time that either shorter or longer RTL in peripheral blood leukocytes is associated with increased glioma risk, which warrants further investigation in the future.

Quantitative assessment of the association between XRCC3 C18607T polymorphism and glioma risk

XRCC3 has an important function in the DNA double-strand break, and XRCC3 C18607T polymorphism is a common polymorphism at exon 7 of the XRCC3 gene. Published data on the association between XRCC3 C18607T polymorphism and glioma risk were inconclusive. Electronic databases of PubMed, and Embase were searched for studies assessing the association between XRCC3 C18607T polymorphism and glioma risk. Pooled odds ratio (OR) and 95 % confidence interval (95 % CI) were calculated to estimate the association. Ten studies with five studies from Caucasians and five studies from Asians were included, including 9,369 subjects. Meta-analysis of total included studies showed that XRCC3 C18607T polymorphism was associated with increased risk of glioma (T vs. C: OR = 1.14, 95 % CI 1.02-1.28, P = 0.02; TT vs. CC: OR = 1.37, 95 % CI 1.03-1.83, P = 0.03; TT vs.

CC/CT

OR = 1.31, 95 % CI 1.00-1.71, P = 0.05; TT/CT vs. CC: OR = 1.12, 95 % CI 1.02-1.22, P = 0.02). Meta-analysis of the five studies from Asians showed that XRCC3 C18607T polymorphism was associated with increased risk of glioma (T vs. C: OR = 1.22, 95% CI 1.09-1.36, P < 0.01; TT vs. CC: OR = 1.89, 95 % CI 1.38-2.57, P < 0.01; TT vs.

CC/CT

OR = 1.78, 95 % CI 1.31-2.40, P < 0.01; TT/CT vs. CC: OR = 1.19, 95 % CI 1.04-1.36, P = 0.01). Meta-analysis of the five studies from Caucasians didn't find the association. In conclusion, the finding from the meta-analysis provides strong evidence for the association between XRCC3 C18607T polymorphism and glioma risk.

Association between XRCC3 Thr241Met polymorphism and risk of brain tumors: a meta-analysis

X-ray repair cross-complementing group 3 (XRCC3) plays an important role in the process of homologous recombination repair for DNA double-strand breaks which further maintains the stability of the genome. XRCC3 Thr241Met polymorphism has been indicated in the development of cancers, but the association of the XRCC3 Thr241Met polymorphism with risk of brain tumors is still unclear owing to the conflicting findings from previous studies. We performed a meta-analysis to provide a better understanding on the association between the XRCC3 Thr241Met polymorphism and risk of brain tumors. The pooled odds ratio (OR) with corresponding 95 % confidence interval (95 % CI) was used to assess the association. Thirteen case-control studies involving a total of 4,984 cases and 7,472 controls were included. Overall, there was no statistically significant association between the XRCC3 Thr241Met polymorphism and risk of brain tumors under all contrast models. Subgroup analysis by race suggested that the XRCC3 Thr241Met polymorphism was associated with increased risk of brain tumors in Asians under all four contrast models (Met vs. Thr: OR = 1.22, 95 % CI 1.09-1.36, P < 0.01; MetMet vs. ThrThr: OR = 1.89, 95 % CI 1.38-2.57, P < 0.01; MetMet vs. ThrThr/ThrMet: OR = 1.78, 95 % CI 1.31-2.40, P < 0.01; and MetMet vs. ThrThr/ThrMet: OR = 1.19, 95 % CI 1.04-1.36, P = 0.01). However, there was no significant association between the XRCC3 Thr241Met polymorphism and risk of brain tumors in Caucasians. Therefore, the XRCC3 Thr241Met polymorphism is associated with increased risk of brain tumors, especially in Asians.

Association between the Thr241Met polymorphism of X-ray repair cross-complementing group 3 gene and glioma risk: evidence from a meta-analysis based on 4,136 cases and 5,233 controls

Genetic polymorphism of X-ray repair cross-complementing group 3 (XRCC3) Thr241Met has been implicated to alter the risk of glioma, but the results are controversial. Medline, PubMed, Embase, and Cochrane Library databases were independently searched by two investigators up to 13 July 2013. Summary odds ratios (OR) and 95% confidence interval (CI) for Thr241Met polymorphism and prostate cancer were calculated. Statistical analysis was performed with the software program Stata 12.0. A total of 10 independent studies, including 4,136 cases and 5,233 controls, were identified. Our analysis suggested that Thr241Met was not associated with glioma risk in overall population. In the subgroup analysis, we detected no significant association between Thr241Met polymorphism and glioma risk in different descent populations. Subgroup analysis was held by source of controls, significant association was found between this polymorphism and glioma risk for population-based studies (homozygote model: OR = 1.747, 95% CI = 1.123-2.717, Ph = 0.059, I(2) = 59.7%; recessive model, OR = 1.455, 95% CI = 1.179-1.795, Ph = 0.111, I(2) = 50.1%; allele model, OR = 1.258, 95% CI = 1.010-1.566, Ph = 0.011, I(2) = 72.9%). This meta-analysis showed the evidence that XRCC3 Thr241Met polymorphism was associated with a low risk of glioma development.

Association between the XRCC3 T241M polymorphism and risk of cancer: evidence from 157 case-control studies

The T241M polymorphism in the X-ray cross-complementing group 3 (XRCC3) had been implicated in cancer susceptibility. The previous published data on the association between XRCC3 T241M polymorphism and cancer risk remained controversial. Hence, we performed a meta-analysis to investigate the association between cancer susceptibility and XRCC3 T241M (61,861 cases and 84,584 controls from 157 studies) polymorphism in different inheritance models. We used odds ratios with 95% confidence intervals to assess the strength of the association. Overall, significantly increased cancer risk was observed in any genetic model (dominant model: odds ration [OR]=1.07, 95% confidence interval [CI]=1.00-1.13; recessive model: OR=1.15, 95% CI=1.08-1.23; additive model: OR=1.17, 95% CI=1.08-1.28) when all eligible studies were pooled into the meta-analysis. In further stratified and sensitivity analyses, the elevated risk remained for subgroups of bladder cancer and breast cancer, especially in Caucasians. In addition, significantly decreased lung cancer risk was also observed. In summary, this meta-analysis suggests the participation of XRCC3 T241M in the susceptibility for bladder cancer and breast cancer, especially in Caucasians, and XRCC3 T241M polymorphism is associated with decreased lung cancer risk. Moreover, our work also points out the importance of new studies for T241M association in some cancer types, such as gastric cancer, colorectal cancer, and melanoma skin cancer, where at least some of the covariates responsible for heterogeneity could be controlled, to obtain a more conclusive understanding about the function of the XRCC3 polymorphism in cancer development.

DNA repair gene ERCC1 and XPD polymorphisms predict glioma susceptibility and prognosis

AIMS

We conducted a case-control study in a Chinese population to clarify the association between polymorphisms in ERCC1 and XPD and susceptibility and survival of glioma.

METHODS

A total of 393 cases and 410 controls were selected from March 2007 to December 2011. Genotyping of ERCC1 and XPD was conducted by TaqMan assays using the ABI Prism 7911HT Sequence Detection System. All analyses were performed using the STATA statistical package.

RESULTS

Polymorphisms in ERCC1 118C/T, ERCC1 8092C/A and XPD Asp312Asn showed no statistically significant difference between glioma cases and controls. However, individuals with the XPD 751Gln/Gln genotype had an increased risk of developing glioma compared with those with the Lys/Lys genotype (adjusted OR=1.64, 95% CI: 1.06-2.89). The ERCC1 118T/T genotype was associated with significantly higher median survival than the ERCC1 C/C genotype (HR=0.67, 95%CI=0.35-0.96). In addition, individuals with XPD 751Gln/Gln had a lower median survival time than XPD Lys/Lys carriers (HR=0.54, 95%CI=0.37- 0.93).

CONCLUSION

In conclusion, we observed that the XPD 751Gln/Gln genotype is associated with glioma susceptibility, and ERCC1 118 T/T and XPD 751Gln/Gln genotypes confer a significantly better prognosis.

The role and clinical significance of DNA damage response and repair pathways in primary brain tumors

Primary brain tumors, in particular, glioblastoma multiforme (GBM), continue to have dismal survivability despite advances in treating other neoplasms. The goal of new anti-glioma therapy development is to increase their therapeutic ratios by enhancing tumor control and/or decreasing the severity and incidence of side effects. Because radiotherapy and most chemotherapy agents rely on DNA damage, the cell's DNA damage repair and response (DRR) pathways may hold the key to new therapeutic strategies. DNA double-strand breaks (DSBs) generated by ionizing radiation and chemotherapeutic agents are the most lethal form of damage, and are repaired via either homologous recombination (HR) or non-homologous end-joining (NHEJ) pathways. Understanding and exploitation of the differences in the use of these repair pathways between tumor and normal brain cells will allow for an increase in tumor cell killing and decreased normal tissue damage. A literature review and discussion on new strategies which can improve the anti-glioma therapeutic ratio by differentially targeting HR and NHEJ function in tumor and normal neuronal tissues is the focus of this article.

Fine mapping of a region of chromosome 11q23.3 reveals independent locus associated with risk of glioma

Background

A single nucleotide polymorphism (SNP) at locus 11q23.3 (rs498872) in the near 5′-UTR of the PHLDB1 gene was recently implicated as a risk factor for gliomas in a genome-wide association study, and this involvement was confirmed in three additional studies.

Methodology/Principal Findings

To identify possible causal variants in the region, the authors genotyped 15 tagging SNPs in the 200 kb genomic region at 11q23.3 locus in a Chinese Han population-based case-control study with 983 cases and 1024 controls. We found evidence for an association between two independent loci (both the PHLDB1 and the ACRN1 genes) and a predisposition for gliomas. Among the multiple significant SNPs in the PHLDB1 gene region, the rs17749 SNP was the most significant [P = 1.31×10⁻⁶ in a recessive genetic model]. Additionally, two novel SNPs (rs2236661 and rs494560) that were independent of rs17749 were significantly associated with glioma risk in a recessive genetic model [P = 1.31×10⁻⁵ and P = 3.32×10⁻⁵, respectively]. The second novel locus was within the ARCN1 gene, and it was associated with a significantly reduced risk for glioma.

Conclusions/Significance

Our data strongly support PHLDB1 as a susceptibility gene for glioma, also shedding light on a new potentially candidate gene, ARCN1.

Variation in DNA repair gene XRCC3 affects susceptibility to astrocytomas and glioblastomas

The gene XRCC3 (X-ray cross complementing group 3) has the task of repairing damage that occurs when there is recombination between homologous chromosomes. Repair of recombination between homologous chromosomes plays an important role in maintaining genome integrity, although it is known that double-strand breaks are the main inducers of chromosomal aberrations. Changes in the XRCC3 protein lead to an increase in errors in chromosome segregation due to defects in centrosomes, resulting in aneuploidy and other chromosomal aberrations, such as small increases in telomeres. We examined XRCC3 Thr241Met polymorphism using PCR-RFLP in 80 astrocytoma and glioblastoma samples. The individuals of the control group (N = 100) were selected from the general population of the São Paulo State. Odds ratio and 95%CI were calculated using a logistic regression model. Patients who had the allele Met of the XRCC3 Thr241Met polymorphism had a significantly increased risk of tumor development (odds ratio = 3.13; 95% confidence interval = 1.50-6.50). There were no significant differences in overall survival of patients. We suggest that XRCC3 Thr241Met polymorphism is involved in susceptibility for developing astrocytomas and glioblastomas.

Arlm1 is a male-specific modifier of astrocytoma resistance on mouse Chr 12

While many cancers show a sex bias, the genetic basis and molecular mechanisms underlying sex bias are not always clear. Astrocytoma and glioblastoma show male predominance in humans. We have shown previously that glial tumors forming in the Nf1-/+; Trp53-/+cis (NPcis) mouse model also show a sex bias in some genetic contexts. Using cross-species comparisons we have identified candidate male-specific modifiers of astrocytoma/glioblastoma. Linkage analysis of B6X(B6X129)-NPcis mice identifies a modifier of astrocytoma resistance specific to males, named Arlm1, on distal mouse Chr 12. Arlm1 is syntenic to human Chr 7p15, 7p21, 7q36, and 14q32 regions that are altered in human glioblastoma. A subset of these genes shows male-specific correlations to glioblastoma patient survival time and represents strong candidates for the Arlm1 modifier gene. Identification of male-specific modifier genes will lead to a better understanding of the molecular basis of male predominance in astrocytoma and glioblastoma.

Association of sequence variants on chromosomes 20, 11, and 5 (20q13.33, 11q23.3, and 5p15.33) with glioma susceptibility in a Chinese population

Two genome-wide association studies of glioma in European populations identified 14 genetic variants strongly associated with risk of glioma, but it is unknown whether these variants are associated with glioma risk in Asian populations. The authors genotyped these 14 variants in 976 glioma patients and 1,057 control subjects to evaluate their associations with risk of glioma, particularly high-grade glioma (glioblastoma; n = 312), in a Chinese population (2004-2009). Overall, the authors identified 3 susceptibility loci for glioma risk at 20q13.33 (RTEL1 rs6010620 (P = 2.79 × 10(-6))), 11q23.3 (PHLDB1 rs498872 (P = 3.8 × 10(-6))), and 5p15.33 (TERT rs2736100 (P = 3.69 × 10(-4))) in this study population; these loci were also associated with glioblastoma risk (20q13.33: RTEL1 rs6010620 (P = 3.57 × 10(-7)); 11q23.3: PHLDB1 rs498872 (P = 7.24 × 10(-3)); 5p15.33: TERT rs2736100 and TERT rs2736098 (P = 1.21 × 10(-4) and P = 2.84 × 10(-4), respectively)). This study provides further evidence for 3 glioma susceptibility regions at 20q13.33, 11q23.3, and 5p15.33 in Chinese populations.

A genetic variant in the APE1/Ref-1 gene promoter -141T/G may modulate risk of glioblastoma in a Chinese Han population

Background

The human apurinic/apyrimidinic endonuclease 1/Redox effector factor-1 (APE1/Ref-1) is implicated in tumor development and progression. Recently, the APE1/Ref-1 promoter -141T/G variant (rs1760944) has been reported to be associated with lung cancer risk. Given the importance of APE1/Ref-1 in both DNA repair and redox activity, we speculate that the -141T/G polymorphism may confer individual susceptibility to gliomas or its subtypes.

Methods

The APE1/Ref-1 -141T/G polymorphism was analyzed in a case-control study including 766 glioma patients (among them 241 glioblastoma, 284 astrocytomas except for glioblastoma and 241 other gliomas) and 824 cancer-free controls from eastern China. Genotyping was performed with Sequenom MassARRAY iPLEX platform by use of allele-specific MALDI-TOF mass spectrometry assay. We estimated odds ratios (ORs) and 95% confidence intervals (95% CIs) using unconditional logistic regression. A test of trend was calculated using the genotype as an ordinal variable in the regression model. For each statistically significant association identified, we estimated the false positive reporting probability (FPRP). FPRP values less than 0.2 were consider to indicate robust associations.

Results

The significant association between the APE1/Ref-1 promoter -141T/G polymorphism and glioma risk was not observed. However, the stratified analysis by histology revealed the variant allele G significantly decreased glioblastoma risk (OR = 0.80, 95% CI = 0.65-0.98, P = 0.032). Individuals with the homozygous -141GG genotype exhibited 46% reduced risk of glioblastoma (adjusted OR = 0.54, 95% CI 0.34-0.87, P = 0.012), compared with the TT homozygote. This result remained robust given the prior probabilities of 25% (FPRP = 0.052) and 10% (FPRP = 0.140), but not with a prior probability of 1% (FPRP = 0.643). The P-associated with the trend test was 0.014.

Conclusions

Our results suggest that a specific genetic variant located in the APE1/Ref-1 promoter may modulate risk of glioblastoma, but not for other histological gliomas. Larger studies with more APE1 polymorphisms are required to validate these preliminary findings.

Risk factors for oligodendroglial tumors: a pooled international study

Oligodendroglial tumors are rare subtypes of brain tumors and are often combined with other glial tumors in epidemiological analyses. However, different demographic associations and clinical characteristics suggest potentially different risk factors. The purpose of this study was to investigate possible risk factors for oligodendroglial tumors (including oligodendroglioma, anaplastic oligodendroglioma, and mixed glioma). Data from 7 case-control studies (5 US and 2 Scandinavian) were pooled. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for age group, gender, and study site. Data on 617 cases and 1260 controls were available for analyses. Using data from all 7 studies, history of allergies and/or asthma was associated with a decreased risk of anaplastic oligodendroglioma (OR = 0.6; 95% CI: 0.4-0.9), and history of asthma only was associated with a decreased risk of oligodendroglioma (OR = 0.5; 95% CI: 0.3-0.9) and anaplastic oligodendroglioma (OR = 0.3; 95% CI: 0.1-0.9). A family history of brain tumors was associated with an increased risk of anaplastic oligodendroglioma (OR = 2.2; 95% CI: 1.1-4.5). Having had chicken pox was associated with a decreased risk of oligodendroglioma (OR = 0.6; 95% CI: 0.4-0.9) and anaplastic oligodendroglioma (OR = 0.5; 95% CI: 0.3-0.9) in the US studies. Although there is some overlap in risk factors between oligodendroglial tumors and gliomas as a group, it is likely that additional factors specific to oligodendroglial tumors have yet to be identified. Large, multi-institution international studies will be necessary to better characterize these etiological risk factors.

Molecular epidemiology of primary brain tumors

Although primary brain tumors (PBTs) are generally considered to be a multifactorial disorder, understanding the genetic basis and etiology of the disease is essential for PBT risk assessment. Understanding of the genetic susceptibility for PBT has come from studies of rare genetic syndromes, linkage analysis, family aggregation, early-onset pediatric cases, and mutagen sensitivity. There are currently no effective markers to assess biological dose of exposures and genetic heterogeneity. The priorities recently recommended by the Brain Tumor Epidemiology Consortium emphasized the need for expanding research in genetics and molecular epidemiology. In this article, we review the literature to identify molecular epidemiologic case-control studies of PBTs that were hypothesis-driven and focused on four hypothesized candidate pathways: DNA repair, cell cycle, metabolism, and inflammation. We summarize the results in terms of genetic associations of single nucleotide polymorphisms of these pathways. We also discuss future research directions based on available evidence and technologies, and conclude that high resolution whole genome approach with significantly large sample size could rapidly advance our understanding of the genetic etiology of PBTs. Literature searches were done on PubMed in March 2009 with the terms glioma, glioblastoma, brain tumor, association, and polymorphism, and we only reviewed English language publications.