Associations between the rs6010620 polymorphism in RTEL1 and risk of glioma: a meta-analysis of 20,711 participants

Pertinence of glioma and single nucleotide polymorphism of TERT, CCDC26, CDKN2A/B and RTEL1 genes in glioma: a meta-analysis

Background

Previous genetic-epidemiological studies considered TERT (rs2736100), CCDC26 (rs4295627), CDKN2A/B (rs4977756) and RTEL1 (rs6010620) gene polymorphisms as the risk factors specific to glioma. However, the data samples of previous genetic-epidemiological studies are modest to determine whether they have definite association with glioma.

Method

The study paid attention to systematically searching databases of PubMed, Embase, Web of Science (WoS), Scopus, Cochrane Library and Google Scholars. Meta-analysis under 5 genetic models, namely recessive model (RM), over-dominant model (O-DM), allele model (AM), co-dominant model (C-DM) and dominant model (DM) was conducted for generating odds ratios (ORs) and 95% confidence intervals (CIs). That was accompanied by subgroup analyses according to various racial groups. The software STATA 17.0 MP was implemented in the study.

Result

21 articles were collected. According to data analysis results, in four genetic models (AM, RM, DM and C-DM) TERT gene rs2736100 polymorphism, CCDC26 gene rs4295627 polymorphism, CDKN2A/B gene rs4977756 polymorphism and RTEL1 gene rs6010620 polymorphisms increased the risk of glioma in Caucasians to different degrees. In Asian populations, the CCDC26 gene rs4295627 polymorphism and CDKN2A/B gene rs4977756 polymorphism did not exhibit a relevance to the risk of glioma. It is suggested to cautiously explain these results as the sample size is small.

Conclusion

The current meta-analysis suggested that the SNP of TERT (rs2736100), CCDC26 (rs4295627), CDKN2A/B (rs4977756) and RTEL1 (rs6010620) genes in glioma might increase risk of glioma, but there are ethnic differences. Further studies evaluating these polymorphisms and glioma risk are warranted.

DNA helicases and their roles in cancer

DNA helicases, known for their fundamentally important roles in genomic stability, are high profile players in cancer. Not only are there monogenic helicase disorders with a strong disposition to cancer, it is well appreciated that helicase variants are associated with specific cancers (e.g., breast cancer). Flipping the coin, DNA helicases are frequently overexpressed in cancerous tissues and reduction in helicase gene expression results in reduced proliferation and growth capacity, as well as DNA damage induction and apoptosis of cancer cells. The seminal roles of helicases in the DNA damage and replication stress responses, as well as DNA repair pathways, validate their vital importance in cancer biology and suggest their potential values as targets in anti-cancer therapy. In recent years, many laboratories have characterized the specialized roles of helicase to resolve transcription-replication conflicts, maintain telomeres, mediate cell cycle checkpoints, remodel stalled replication forks, and regulate transcription. In vivo models, particularly mice, have been used to interrogate helicase function and serve as a bridge for preclinical studies that may lead to novel therapeutic approaches. In this review, we will summarize our current knowledge of DNA helicases and their roles in cancer, emphasizing the latest developments.

Replication of GWAS identifies RTEL1, CDKN2A/B, and PHLDB1 SNPs as risk factors in Portuguese gliomas patients

Diffuse gliomas are the most common malignant primary brain tumors and remain incurable. A better knowledge of the tumor etiology is required. Specific single nucleotides polymorphisms (SNPs) rs4977756 (CDKN2A/B), rs6010620 (RTEL1), rs498872 (PHLDB1), rs2736100 (TERT), and rs4295627 (CCDC26) have been associated with glioma susceptibility and are potential risk biomarkers. This study aimed to analyze five SNPs associated with glioma susceptibility, in the Portuguese population. SNPs were genotyped using the Sequenom MassARRAY platform in 127 gliomas and 180 controls. Unconditional logistic regression models were used to calculate odds ratio (OR) and 95% confidence intervals. The false-positive report probability was also assessed. The associations between polymorphisms and survival were evaluated using the log-rank test. It was found that the AG and GG genotypes of the rs4977756 (CDKN2A/B) were associated with an increased risk of gliomas (OR 1.85 and OR 2.38) and glioblastomas (OR 2.77 and OR 3.94). The GA genotype of the rs6010620 (RTEL1) was associated with a decreased risk of glioblastomas (OR 0.45). We also observed that the GA genotype of the rs498872 (PHLDB1) was associated with an increased risk of gliomas (OR 2.92) and glioblastomas (OR 2.39). No significant risk associations were found for the rs2736100 (TERT) and rs4295627 (CCDC26). In addition, the genotype AA of the rs498872 (PHLDB1) was associated with poor overall survival of gliomas patients (AA vs. GA, p = 0.037). The rs6010620 (RTEL1), rs4977756 (CDKN2A/B), and rs498872 (PHLDB1) are associated with glioma risk in the Portuguese population and these data may contribute to understanding gliomas etiology.

Association analysis of RTEL1 variants with risk of adult gliomas in a Korean population

Previous studies have identified multiple loci for inherited susceptibility to glioma development, including the regulator of telomere elongation helicase 1 (RTEL1). However, the association between RTEL1 variants and risk of glioma has not been well understood. Therefore, we sought to comprehensively examine the genetic interaction between RTEL1 variants and risk of glioma with respect to defined histological and molecular subtypes. We employed a case-control study involving 250 adult glioma patients with previous molecular alterations and 375 population–based controls within Korean populations. Statistical analyses on the association between RTEL1 single nucleotide polymorphisms (SNPs) and glioma risk were conducted using unconditional logistic regression. Additional conditional and stepwise analyses were performed on significant RTEL1 SNPs. We detected significant associations (Bonferroni P < .05) between six SNPs (rs6089953, rs3848669, rs6010620, rs3787089, rs6062302, and rs115303435) and risk of glioma in the Korean subjects. The two coding variants, rs6062302 (D664D) and rs115303435 (A1059T), were plausibly causal variants and were independent among the significantly associated RTEL1 variants. The glioma subgroup analyses showed that the causal variants (rs6062302 and rs115303435) may be associated with increased risk of glioma regardless of histological grades and molecular alterations. This study provides a deeper understanding of relationships between RTEL1 variants and risk of glioma. Further studies are required to ascertain the impact of those variants on glioma susceptibility.

Association of the CCDC26 rs4295627 polymorphism with the risk of glioma: Evidence from 7,290 cases and 11,630 controls

Published data on the association between the coiled-coil domain-containing 26 (CCDC26) rs4295627 polymorphism and the risk of glioma have been inconclusive. To further investigate this association, a meta-analysis was performed. By a comprehensive literature search using PubMed and EMBASE databases, a total of 16 case-control studies were identified for inclusion in the meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess this association. Our results confirmed that the risk with allele G was higher compared with that with allele T for glioma. The results indicated that the allele G of rs4295627 polymorphism in the CCDC26 gene was associated with increased risk of glioma in the homozygote model (GG vs. TT, OR=1.936, 95 %CI: 1.500-2.658, P<0.001), the heterozygote model (GT vs. TT, OR=1.323, 95% CI: 1.241-1.412, P=0.206), the dominant model (GG+GT vs. TT, OR=1.375, 95% CI: 1.256-1.505, P=0.026), the recessive model (GG vs. GT+TT, OR=1.769, 95% CI: 1.302-2.403, P<0.001) and the allele model (G vs. T, OR=1.310, 95% CI: 1.185-1.448, P<0.001). Current evidence suggests that the rs4295627 polymorphism in the CCDC26 gene may contribute to glioma susceptibility. However, further case-control studies are required to confirm our results.

Genetic variant near TERC influencing the risk of gliomas with older age at diagnosis in a Chinese population

A recent genome-wide association study has identified an association between rs1920116 near TERC and high-grade glioma in populations of European ancestry. In order to evaluate the effect of the SNP rs1920116 near TERC in the Chinese population, we examined associations of this candidate SNP with glioma in a sample of 1970 Chinese Han individuals. SNP genotype data were available for 980 Chinese glioma patients and 990 healthy controls. Logistic regression analyses were performed to evaluate the association between rs1920116 and glioma risk adjusted for age, gender and stratified by tumor grade where appropriate. The allele G at TERC rs1920116 are risk factors for gliomas, and its association with glioma risk was consistent across tumor subgroups in the Chinese Han population (OR = 1.18-1.21). In order to assess variation in SNP effect size at different patient ages, glioma cases and controls were divided into 3 age strata, in years: <50, 50-59, and 60+. The results of multiple logistic regression analyses indicate that the SNP has age-specific effects on the risk of developing glioma. Our report confirmed the effects of rs1920116 near TERC on glioma occurring in older peoples in the Chinese Han population for the first time. As TERC is a candidate for inter-individual variation in telomere length, our study supports the hypothesis that telomerase-related mechanisms of telomere maintenance are more associated with gliomas that develop later in life.