Genetic variations in TERT-CLPTM1L locus are associated with risk of lung cancer in Chinese population

Evaluation of possible role of the hTERT gene rs2853669 polymorphism in the development of colorectal cancer as a genetic risk factor

Colorectal cancer (CRC) is the second deadliest malignancy. Human telomerase reverse transcriptase (hTERT) gene has been identified as one of the potential cancer susceptibility genes. We evaluated the relationship between the risk of CRC and CRC's clinicopathological features of the hTERT rs2853669 (A > G/T > C, by the chain direction) polymorphism in Turkish population. The rs2853669 polymorphism was investigated with the LightCycler 96 device in 100 CRC patients and 327 controls. We found that the rs2853669 polymorphism AG/GG genotypes in genetic models reduced the risk of CRC. However, there was no significant relationship between rs2853669 polymorphism and clinicopathological features of CRC in studied population. The results of this study showed that the risk of colorectal cancer is significantly reduced in the individuals having the G (C) allele. Our recommendation is to analyze the hTERT gene expression by studying the hTERT promoter mutations with this polymorphism in colorectal cancer.

Human TERT promoter polymorphism rs2853669 is associated with cancers: an updated meta-analysis

The polymorphism rs2853669 in the telomerase reverse transcriptase gene (TERT) promoter region is widely investigated for the risk of different cancers. However, previous results remained inconclusive. Thus, we performed this updated meta-analysis to comprehensively evaluate the association between rs2853669 and the susceptibility of human cancer. A systematic literature search via PubMed, EMBASE, Cochrane Library, and Web of Science databases was conducted that produced a total of 19 eligible studies containing 23,085 subjects. The relationship was calculated with the odds ratio (OR) and 95% confidence intervals (CIs). Statistical analyses were performed using the RevMan 5.4 software. The analysis indicated that rs2853669 is associated with an enhanced risk of overall cancer risk. From subgroup analysis, a significantly increased association in five genetic models (p < 0.05) was found among Asians, but no association was observed in Caucasians. Although we did not find any significant correlation between rs2853669 and breast cancer, an increased and statistically significant association was found for both lung cancer and acute myeloid leukemia. We did not find any association in other cancer types during stratified analysis. Our meta-analysis suggests that rs2853669 polymorphism in TERT gene is associated with an increased risk of overall cancer susceptibility, particularly in the Asian population. Moreover, rs2853669 is significantly associated with lung cancer and acute myeloid lymphoma. However, large-scale studies are needed to confirm our findings.

Association between TERT gene polymorphisms and acute myeloid leukemia susceptibility in a Chinese population: a case-control study

Background

The aim of this study was to investigate the association between telomerase reverse transcriptase (TERT) gene polymorphisms and acute myeloid leukemia (AML) susceptibility in a Chinese Han population.

Methods

A total of 102 AML patients and 108 healthy controls were enrolled in this case-control study. TERT gene rs2853669 and rs2736100 polymorphisms were genotyped via polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Chi-square test was applied to compare polymorphism distributions between case and control groups. The strength of the association between TERT gene polymorphisms and AML susceptibility was evaluated utilizing odds ratio (OR) with corresponding 95% confidence interval (CI).

Results

CC genotype and C allele of rs2736100 polymorphism were more frequent in AML patients (P < 0.05), and individuals carrying CC genotype showed higher risk of suffering from AML (OR = 2.632, 95% CI 1.129-6.133). But for rs2853669 polymorphism, no significant differences were detected in either genotype or allele distributions between groups (P > 0.05).

Conclusions

This study suggested a positive association between TERT gene rs2736100 polymorphism and AML susceptibility in Chinese Han population.

CASC15 polymorphisms are correlated with cervical cancer susceptibility in Chinese women

Background

Cervical cancer is a frequent, common cancer in women, and causes high cancer‐related deaths among women in our world. Accumulating studies provided an important evidence for long noncoding RNA (lncRNA) polymorphisms in the susceptibility of various cancer. Here, we recruited 494 cervical cancer cases and 504 unrelated controls to assess the relationship between CASC15 (OMIM# 616610) polymorphisms and cervical cancer susceptibility.

Methods

Agena MassARRAY platform was conducted to genotype CASC15 polymorphisms. Odds ratios (ORs) and 95% confidence intervals (CIs) were analyzed through logistic regression to adjust for confounding factors, such as age and gender.

Results

Our study suggested that rs12212674 (NC_000006.12:g.22086845T>A) “A” allele was significantly associated with an increased risk of cervical cancer (OR = 1.31, 95% CI = 1.01–1.69, p = .041). The result was demonstrated in the log‐additive model (OR = 1.32, 95% CI = 1.02–1.72, p = .037). After age stratification, we also found that the “TT” genotype of rs4712653 (NC_000006.11:g.22125964T>C) in CASC15 was interaction with a higher cervical cancer risk in subjects aged ≤51 years in the co‐dominant model (OR = 2.08, 95% CI = 1.02–4.25, p = .044) and the recessive model (OR = 2.11, 95% CI = 1.05–4.24, p = .036). Whereas no significant correlation was found among other SNPs of CASC15 polymorphisms and the risk of cervical cancer. MDR analysis illustrated that the interaction between rs7740084 (NC_000006.11:g.21727531G>A), rs1555529 (NC_000006.11:g.21691704A>G), and rs12212674 had a certain effect on the progress of cervical cancer.

Conclusion

Our results revealed a potential interaction between CASC15 polymorphisms and cervical cancer susceptibility. The results provided important insights into CASC15 function in the development of cervical cancer.

Association of TERT, OGG1, and CHRNA5 Polymorphisms and the Predisposition to Lung Cancer in Eastern Algeria

Lung cancer remains the most common cancer in the world. The genetic polymorphisms (rs2853669 in TERT, rs1052133 in OGG1, and rs16969968 in CHRNA5 genes) were shown to be strongly associated with the risk of lung cancer. Our study's aim is to elucidate whether these polymorphisms predispose Eastern Algerian population to non-small-cell lung cancer (NSCLC). To date, no study has considered this association in the Algerian population. This study included 211 healthy individuals and 144 NSCLC cases. Genotyping was performed using TaqMan probes and Sanger sequencing, and the data were analyzed using multivariate logistic regression adjusted for covariates. The minor allele frequencies (MAFs) of TERT rs2853669, CHRNA5 rs16969968, and OGG1 rs1052133 polymorphisms in controls were C: 20%, A: 31%, and G: 29%, respectively. Of the three polymorphisms, none shows a significant association, but stratified analysis rs16969968 showed that persons carrying the AA genotype are significantly associated with adenocarcinoma risk (pAdj = 0.03, ORAdj = 2.55). Smokers with an AA allele have a larger risk of lung cancer than smokers with GG or GA genotype (pAdj = 0.03, ORAdj = 3.91), which is not the case of nonsmokers. Our study suggests that CHRNA5 rs16969968 polymorphism is associated with a significant increase of lung adenocarcinoma risk and with a nicotinic addiction.

Association between functional TERT promoter polymorphism rs2853669 and cervical cancer risk in South Indian women

A single nucleotide polymorphism (SNP) rs2853669 (A>G) in the telomerase reverse transcriptase (TERT) promoter has recently been reported in chr5:1,295,349 T>C (T349C), and was shown to be associated with increased cancer risk and poor survival in a specific population. However, at present, the role of this particular SNP with TERT promoter driver mutations and its genetic association with human papilloma virus (HPV) in patients with cervical cancer has not been determined. In the present study, the genetic association of the functional SNP rs2853669 in the presence/absence of TERT promoter hotspot mutations and HPV in patients with cervical cancer of South Indian origin was evaluated. To understand and compare the frequency of the variant allele and its risk association in different cancer types of various populations, the SNP was genotyped in 257 cervical cancer samples and 295 controls, and its associations with TERT promoter hotspot mutations and HPV were analyzed. Furthermore, an extensive search of previously published articles in PubMed, Embase and Web of Science was conducted; a meta-analysis was carried out to elucidate the association of the SNP with different cancer types in global populations. The SNP analysis showed significantly high frequency (41%) of homozygous variant allele rs2853669 (GG) in patients with cervical cancer compared with control samples [Recessive allele model odds ratio (OR)=1.71; 95% CI=1.20-2.43; P=0.003]. No significant interaction was observed between the TERT SNP rs2853669 and HPV status as well as other hotspot TERT promoter (C228T and C250T) mutations determined in our previous study. In addition, the overall meta-analysis revealed a significant association of the SNP rs2853669 with other cancer types in different ethnic populations (OR=1.09; 95% CI=1.03-1.16; P=0.004). The present results suggested that the TERT SNP rs2853669 could play an important role in the risk of cervical cancer in a South Indian population.

Therapeutic targeting of the NRF2 and KEAP1 partnership in chronic diseases

The transcription factor NF-E2 p45-related factor 2 (NRF2; encoded by NFE2L2) and its principal negative regulator, the E3 ligase adaptor Kelch-like ECH-associated protein 1 (KEAP1), are critical in the maintenance of redox, metabolic and protein homeostasis, as well as the regulation of inflammation. Thus, NRF2 activation provides cytoprotection against numerous pathologies including chronic diseases of the lung and liver; autoimmune, neurodegenerative and metabolic disorders; and cancer initiation. One NRF2 activator has received clinical approval and several electrophilic modifiers of the cysteine-based sensor KEAP1 and inhibitors of its interaction with NRF2 are now in clinical development. However, challenges regarding target specificity, pharmacodynamic properties, efficacy and safety remain.

A missense variant in PTPN12 associated with the risk of colorectal cancer by modifying Ras/MEK/ERK signaling

BACKGROUND

The classical protein tyrosine phosphatases (PTPs) have been widely reported to be associated with various human malignancies including colorectal cancer (CRC). However, there are few comprehensive analyses of the association between the classical PTP genes and CRC risk.

METHODS

First, a bioinformatics analysis was performed to identify missense variants within the classical PTP gene family. Second, exome-wide association data and an independent population study were conducted to evaluate effects of candidate variants on CRC risk. Finally, functional assays based on signaling pathways were applied to uncover the potential pathogenic mechanism.

RESULTS

We identified that PTPN12 rs3750050 G allele presented a 19% increase the risk of CRC, with an OR of 1.19 (95% CI = 1.09-1.30, P =  1.015×10^-4) under an additive model in the combined analysis. Furthermore, biochemical assays illustrated that rs3750050 could impair the inhibitory effect of PTPN12 on Ras/MEK/ERK signaling by impeding SHC dephosphorylation, increase the expression of cyclin D1 and ultimately lead to aberrant cell proliferation, thus contributing to CRC pathogenesis.

CONCLUSION

Our study highlights that PTPN12 rs3750050 could increase CRC risk by modifying Ras/MEK/ERK signaling. This work provides a novel insight into the roles of genetic variants within PTP genes in the pathogenesis of CRC.

DUB3 deubiquitinates and stabilizes NRF2 in chemotherapy resistance of colorectal cancer

The transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2) is one of the master regulators that control hundreds of genes containing antioxidant response elements (AREs). The NRF2-ARE pathway plays a complex role in colorectal cancer (CRC). NRF2 activity is known to be regulated by KEAP1-CUL3 E3 ligase-mediated ubiquitination, indicating the importance of deubiquitination regulation. However, the deubiquitinase (DUB) of NRF2 remains unknown. Here, by screening a DUB library, we identified DUB3 as a DUB that remarkably stabilized NRF2. Further experiments demonstrated that DUB3 promoted NRF2 stability and transcriptional activity by decreasing the K48-linked ubiquitination of NRF2. Coimmunoprecipitation studies revealed interactions between NRF2 and DUB3, as well as between KEAP1 and DUB3, indicating that NRF2, DUB3, and KEAP1 formed a large functional complex. Importantly, ectopic expression of DUB3 caused NRF2-dependent chemotherapy resistance in colon cancer cell lines. Thus, to the best of our knowledge, our findings are the first to identify DUB3 as a NRF2 DUB and may provide a new strategy against chemotherapy resistance in CRC and other NRF2-related diseases.

Telomere Maintenance Mechanisms in Cancer

Tumour cells can adopt telomere maintenance mechanisms (TMMs) to avoid telomere shortening, an inevitable process due to successive cell divisions. In most tumour cells, telomere length (TL) is maintained by reactivation of telomerase, while a small part acquires immortality through the telomerase-independent alternative lengthening of telomeres (ALT) mechanism. In the last years, a great amount of data was generated, and different TMMs were reported and explained in detail, benefiting from genome-scale studies of major importance. In this review, we address seven different TMMs in tumour cells: mutations of the TERT promoter (TERTp), amplification of the genes TERT and TERC, polymorphic variants of the TERT gene and of its promoter, rearrangements of the TERT gene, epigenetic changes, ALT, and non-defined TMM (NDTMM). We gathered information from over fifty thousand patients reported in 288 papers in the last years. This wide data collection enabled us to portray, by organ/system and histotypes, the prevalence of TERTp mutations, TERT and TERC amplifications, and ALT in human tumours. Based on this information, we discuss the putative future clinical impact of the aforementioned mechanisms on the malignant transformation process in different setups, and provide insights for screening, prognosis, and patient management stratification.

Association between TERT rs2853669 polymorphism and cancer risk: A meta-analysis of 9,157 cases and 11,073 controls

Background

It has been reported that the functional telomerase reverse transcriptase (TERT) rs2853669 polymorphism might contribute to different types of human cancer. However, the association of this mutation with cancer remains controversial. Here, we conducted a meta-analysis to characterize this relationship.

Materials and methods/Main results

A systematic search of studies on the association of TERT rs2853669 polymorphism with all types of cancer was conducted in PubMed, Embase and Cochrane Library. The summary odds ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were used to pool the effect size in a fixed-effects model or a random-effects model where appropriate. A total of 13 articles and 15 case-control studies, including 9,157 cases and 11,073 controls, were included in this meta-analysis. Overall, the pooled results indicated that the rs2853669 polymorphism was significantly associated with increased cancer risk in a homozygote comparison model (CT vs. TT: OR = 1.085, 95% CI: 1.015–1.159, P = 0.016). In the stratified analyses, a significant increased cancer risk was observed in Asian, but not Caucasian patients. A subgroup analysis by cancer type also revealed a significant increase in the risk of lung cancer, but not breast cancer.

Conclusions

The results of this meta-analysis suggest that the TERT rs2853669 polymorphism is associated with a significantly increased risk of cancer, particularly lung cancer, in Asian populations.

Scutellaria baicalensis and Cancer Treatment: Recent Progress and Perspectives in Biomedical and Clinical Studies

Scutellaria baicalensis (Huangqin in Chinese) is a major traditional Chinese medicine (TCM) herb, which has a long history of use in the treatment of a variety of symptoms correlated with cancer. In the past decade, the potential of S. baicalensis and single compounds derived from it as anticancer agents targeting various pathways has received extensive research attention. Specifically, the proliferation and metastases inhibiting properties of the single compounds in cancer have been studied; however, the underlying mechanisms remain unclear. This review summarizes the various mechanisms, pathways and molecular targets involved in the anticancer activity of S. baicalensis and its single compounds. However, the aim of this review is to provide a more thorough view of the last 10 years to link traditional use with modern research and to highlight recently discovered molecular mechanisms. Extracts and major flavonoids derived from S. baicalensis have been found to possess anticancer effects in multiple cancer cell lines both in vitro and in vivo. Further investigation is warranted to better understand the underlying mechanisms and to discover novel targets and cancer therapeutic drugs that may improve both the survival and quality of life of cancer patients.

Parthenolide prevents resistance of MDA-MB231 cells to doxorubicin and mitoxantrone: the role of Nrf2

Triple-negative breast cancer is a group of aggressive cancers with poor prognosis owing to chemoresistance, recurrence and metastasis. New strategies are required that could reduce chemoresistance and increases the effectiveness of chemotherapy. The results presented in this paper, showing that parthenolide (PN) prevents drug resistance in MDA-MB231 cells, represent a contribution to one of these possible strategies. MDA-MB231 cells, the most studied line of TNBC cells, were submitted to selection treatment with mitoxantrone (Mitox) and doxorubicin (DOX). The presence of resistant cells was confirmed through the measurement of the resistance index. Cells submitted to this treatment exhibited a remarkable increment of NF-E2-related factor 2 (Nrf2) level, which was accompanied by upregulation of catalase, MnSOD, HSP70, Bcl-2 and P-glycoprotein. Moreover, as a consequence of overexpression of Nrf2 and correlated proteins, drug-treated cells exhibited a much lower ability than parental cells to generate ROS in response to a suitable stimulation. The addition of PN (2.0 μM) to Mitox and DOX, over the total selection time, prevented both the induction of resistance and the overexpression of Nrf2 and correlated proteins, whereas the cells showed a good ability to generate ROS in response to adequate stimulation. To demonstrate that Nrf2 exerted a crucial role in the induction of resistance, the cells were transiently transfected with a specific small interfering RNA for Nrf2. Similarly to the effects induced by PN, downregulation of Nrf2 was accompanied by reductions in the levels of catalase, MnSOD, HSP70 and Bcl-2, prevention of chemoresistance and increased ability to generate ROS under stimulation. In conclusion, our results show that PN inhibited the development of the resistance toward Mitox and DOX, and suggest that these effects were correlated with the prevention of the overexpression of Nrf2 and its target proteins, which occurred in the cells submitted to drug treatment.

Polymorphisms in human telomerase reverse transcriptase (hTERT) gene, gene- gene and gene-smoking interaction with susceptibility to gastric cancer in Chinese Han population

Aims

To investigate the association of telomerase reverse transcriptase (TERT) gene polymorphisms and additional gene-gene and gene- environment interaction with gastric cancer (GC) risk.

Results

GC risk was significantly higher in carriers of G allele of rs2736100 than those with TT genotype (TG+ GG versus TT), adjusted OR (95%CI) =1.68 (1.26-2.17), and higher in carriers of G allele of rs2853669 than those with AA genotype (AG+ GG versus AA), adjusted OR (95%CI) = 1.72 (1.19-2.33). We also found that interaction between rs2736100 and smoking was associated with higher GC risk. Smokers with TG or GG of rs2736100 genotype have elevated GC risk, compared to never- smokers with TT of rs2736100 genotype, OR (95%CI) = 3.12 (1.82 -4.61). Pairwise linkage equilibrium (LD) analysis between SNPs was measured and the D’ value between rs2736100 and rs2736109 was more than 0.8. A haplotype containing the rs2736100- G and rs2736109- A alleles was associated with a statistically increased GC risk (OR= 2.66, 95%CI= 1.28 – 4.12, p<0.0001).

Materials and Methods

A total of 1088 participants (686 males, 402 females) were selected, including 360 GC patients and 728 normal participants. Logistic regression was performed to investigate association between single nucleotide polymorphisms (SNPs) within TERT gene and GC susceptibility. Generalized multifactor dimensionality reduction (GMDR) model was used to screen gene- gene and gene- environment interaction combinations.

Conclusions

We found that G allele of rs2736100 and G allele of rs2853669 in TERT gene, interaction between rs2736100 and smoking, and haplotype containing the rs2736100- G and rs2736109- A alleles were all associated with increased GC risk.

Frequency and geographic distribution of TERT promoter mutations in primary hepatocellular carcinoma

Primary hepatocellular carcinoma (HCC) mainly develops in subjects chronically infected with hepatitis B (HBV) and C (HCV) viruses through a multistep process characterized by the accumulation of genetic alterations in the human genome. Nucleotide changes in coding regions (i.e. TP53, CTNNB1, ARID1A and ARID2) as well as in non-coding regions (i.e. TERT promoter) are considered cancer drivers for HCC development with variable frequencies in different geographic regions depending on the etiology and environmental factors. Recurrent hot spot mutations in TERT promoter (G > A at-124 bp; G > A at -146 bp), have shown to be common events in many tumor types including HCC and to up regulate the expression of telomerases. We performed a comprehensive review of the literature evaluating the differential distribution of TERT promoter mutations in 1939 primary HCC from four continents. Mutation rates were found higher in Europe (56.6%) and Africa (53.3%) than America (40%) and Asia (42.5%). In addition, HCV-related HCC were more frequently mutated (44.8% in US and 69.7% in Asia) than HBV-related HCC (21.4% in US and 45.5% in Africa). HCC cases associated to factors other than hepatitis viruses are also frequently mutated in TERT promoter (43.6%, 52.6% and 57.7% in USA, Asia and Europe, respectively). These results support a major role for telomere elongation in HCV-related and non-viral related hepatic carcinogenesis and suggest that TERT promoter mutations could represent a candidate biomarker for the early detection of liver cancer in subjects with HCV infection or with metabolic liver diseases.

Association between rs2853669 in TERT gene and the risk and prognosis of human cancer: a systematic review and meta-analysis

The polymorphism rs2853669 within the promoter of telomerase reverse transcriptase gene (TERTp) has been debated about its role in cancer risk and prognosis. Additionally, several studies report inconsistent results concerning the modifying effect of rs2853669 on the prognostic value of TERTp mutations in cancer patients. Here, we performed this meta-analysis to comprehensively evaluate the role of rs2853669 in the risk and prognosis of human cancer, and further assess its modifying impact on TERTp mutations in the survival of cancer patients. We systematically searched literature via PubMed, Web of Science, and EMBASE through July 2016, and included 22 eligible studies. The overall analysis (64,119 cases and 78,988 controls) demonstrated that rs2853669 did not increase or decrease the overall cancer risk. Subsequent analyses also did not reveal any association between rs2853669 and overall cancer prognosis. However, we identified a modifying effect of rs2853669 on TERTp mutations in that, among cancer patients with TERTp mutations, only those carrying the TT genotype had a poor survival (Hazard ratio = 1.56, 95% confidence interval = 1.06-2.28); subgroup analyses by cancer type also supported these results. In conclusion, our findings suggest that rs2853669 could be important for assessing the prognostic value of TERTp mutations. Future large studies are required to further validate our results.

The associations of TERT-CLPTM1L variants and TERT mRNA expression with the prognosis of early stage non-small cell lung cancer

Lung cancer is the leading cause of cancer-related death in the world. Several genome-wide association studies (GWAS) have identified TERT-CLPTM1L as plausible causative locus for lung cancer development. This study aimed to investigate the associations of genetic variations in TERT-CLPTM1L and the expression level of TERT with the survival of early stage non-small cell lung cancer (NSCLC) patients. We selected three single-nucleotide polymorphisms of TERT-CLPTM1L (rs2853669, rs2736108 and rs31490) and genotyped in 140 early stage NSCLC patients by TaqMan assay. Associations between these variations and survival outcome of early stage NSCLC patients were further investigated. We also used TCGA data to evaluate the associations of TERT messenger RNA (mRNA) expression and survival outcome of early stage NSCLC patients. Survival analysis showed that, compared with early NSCLC patients carrying TERT rs2853669 TT+TC genotypes, patients with rs2853669 CC genotype had significantly longer median survival time (MST=102.2 vs 52.4 months; log-rank P=0.028) and lower death risk [hazard ratio (HR) with 95% confidence interval (CI))=0.38(0.17-0.82), P=0.014]. Early NSCLC patients carrying TERT rs2736108 AA genotype had significantly shorter MST (MST=29.0 vs 63.3 months; log-rank P=0.020) and increased death risk [HR (95% CI)=2.22(1.01-5.80), P=0.046], when compared with patients carrying rs2736108 GG genotypes. TCGA data revealed that early NSCLC patients with higher expression level of TERT mRNA in lung tumor tissues had a longer MST and decreased death risk than those with low expression level of TERT mRNA [MST=54.4 vs 49.0 months; log-rank P=0.041; adjusted HR (95% CI)=0.68(0.50-0.94)]. These findings may add potential evidence to understand the prognostic value of TERT and provide a new prospect of individualized prevention and treatment for early stage NSCLC.

The identification of two regulatory ESCC susceptibility genetic variants in the TERT-CLPTM1L loci

The chromosome 5p15.33 TERT-CLPTM1L region has been identified by genome-wide association studies as a susceptibility locus of multiple malignancies. However, the involvement of this locus in esophageal squamous cell carcinoma (ESCC) development is still largely unclear. We fine-mapped the TERT-CLPTM1L region through genotyping 15 haplotype-tagging single nucleotide polymorphisms (htSNPs) using a two stage case-control strategy. After analyzing 2098 ESCC patients and frequency-matched 2150 unaffected controls, we found that rs2853691, rs2736100 and rs451360 genetic polymorphisms are significantly associated with ESCC risk in Chinese (all P<0.05). Reporter gene assays indicated that the ESCC susceptibility SNP rs2736100 locating in a potential TERT intronic promoter has a genotype-specific effect on TERT expression. Similarly, the CLPTM1L rs451360 SNP also showed allelic impacts on gene expression. After measuring TERT and CLPTM1L expression in sixty-six pairs of esophageal cancer and normal tissues, we observed that the rs2736100 G risk allele carriers showed elevated oncogene TERT expression. Also, subjects with the rs451360 protective T allele had much lower oncogene CLPTM1L expression than those with G allele in tissue specimens. Results of these analyses underline the complexity of genetic regulation of telomere biology and further support the important role of telomerase in carcinogenesis. Our data also support the involvement of CLPTM1L in ESCC susceptibility.

The TERT promoter SNP rs2853669 decreases E2F1 transcription factor binding and increases mortality and recurrence risks in liver cancer

A common single-nucleotide polymorphism in the telomerase reverse transcriptase (TERT) promoter, rs2853669 influences patient survival rates and the risk of developing cancer. Recently, several lines of evidence suggest that the rs2853669 suppresses TERT promoter mutation-mediated TERT expression levels and cancer mortality as well as recurrence rates. However, no reports are available on the impact of rs2853669 on TERT expression in hepatocellular carcinoma (HCC) and its association with patient survival. Here, we found that HCC-related overall and recurrence-free survival rates were not associated with TERT promoter mutation individually, but rs2853669 and the TERT promoter mutation in combination were associated with poor survival rates. TERT mRNA expression and telomere fluorescence levels were greater in patients with HCC who had both the combination. The combination caused TERT promoter methylation through regulating the binding of DNA methyltransferase 1 and histone deacetylase 1 to the TERT promoter in HCC cell lines. The TERT expression level was significantly higher in HCC tumor with a methylated promoter than in that with an unmethylated promoter. In conclusion, we demonstrate a substantial role for the rs2853669 in HCC with TERT promoter mutation, which suggests that the combination of the rs2853669 and the mutation indicate poor prognoses in liver cancer.

Common variations in TERT-CLPTM1L locus are reproducibly associated with the risk of nasopharyngeal carcinoma in Chinese populations

Associations between single nucleotide polymorphisms (SNPs) at 5p15 (TERT-CLPTM1L) and multiple cancer types have been reported. We examined whether polymorphisms in the TERT-CLPTM1L locus were related to the risk of developing nasopharyngeal carcinoma (NPC) among Chinese populations. In the first stage, 26 tag SNPs were genotyped in a Guangxi population (855 patients and 1036 controls). In the second stage, the SNPs, which showed significant association, were further genotyped in a Guangdong population (997 patients and 972 controls). Functional analyses were conducted to verify the biological relevance of the associated polymorphism. In the 1st stage, four SNPs (rs2736098, rs2735845, rs402710, and rs401681) were significantly associated with the risk of developing NPC. After the 2nd stage validation, rs2735845 and rs401681 were independently associated with the risk of developing NPC in the additive model (rs2735845, OR = 1.19, 95% CI = 1.04–1.37, P = 0.011; rs401681, OR = 0.85, 95% CI = 0.74–0.99, P = 0.034). Furthermore, we observed higher CLPTM1L messenger RNA levels in fetal mesenchymal stem cells from the rs2735845 G allele carriers compared with that from non-carriers. In addition, using an immunohistochemistry assay, we observed higher TERT and CLPTM1L levels in NPC tissues compared with that in non-cancerous nasopharyngeal tissues. Our findings suggest that polymorphisms in the TERT-CLPTM1L locus may play a role in mediating the susceptibility to NPC in Chinese populations.

Genetic variations in the TERT and CLPTM1L gene region and gastrointestinal stromal tumors risk

Recent studies have suggested polymorphisms in the TERT and CLPTM1L region are associated with carcinogenesis of many distinct cancer types, including gastrointestinal cancers. However, the contribution of polymorphisms in the TERT and CLPTM1L gene region to gastrointestinal stromal tumors (GISTs) risk is still unknown. We tested the six tagSNPs on TERT and CLPTM1L region with GIST risk, using a population-based, two-stage, case-control study in 2,000 subjects. Functional validation was conducted to validate our findings of TERT rs2736098 and explore its influence on relative telomere length (RTL) in GIST cells. It showed that variant rs2736098 was significantly associated with increased risk of GIST (per allele OR = 1.29, 95% CI: 1.14–1.47, P = 7.03 × 10⁻⁵). The difference remain significant after Bonferroni correction (P = 7.03 × 10⁻⁵ * 6 = 4.2 × 10⁻⁴). Real-time PCR showed carriers of genotype CC have the longest RTL, following by carriers of genotype CT, while carriers of genotype TT have the shortest RTL in GIST tissues (P < 0.001). Our data provide evidence to implicate TERT rs2736098 polymorphism as a novel susceptibility factor for GIST risk.

Associations between genetic variants located in mature microRNAs and risk of lung cancer

MiRNAs have been focused for their wide range of biological regulatory functions. Previous studies have suggested that individual miRNAs could influence tumorigenesis through their regulation of specific proto-oncogenes and tumor suppressor genes. This study was implemented to investigate the associations between SNPs in mature microRNAs (miRNAs) and development of lung cancer in a two-stage, case-control study, followed by some functional validations. First, 11 SNPs were analyzed in a case-control study of lung cancer, and the significant results were validated in an additional population. Our results showed that rs3746444 in mir-499 (allele C vs T: OR = 1.33; 95% CI = 1.15-1.54; P = 1.2 × 10-4) and rs4919510 in mir-608 (allele G vs C: OR = 1.27; 95% CI= 1.13-1.43; P = 5.1 × 10-5) were significantly associated with increased risk of lung cancer. Rs3746444 in mir-499 was also significantly associated with poor survival of lung cancer (HR, 1.35; 95% CI, 1.15-1.58; P = 0.0002). The expression levels of mir-499 and mir-608 were significantly lower than those of adjacent normal tissues (P < 0.0005), and the carriers of minor alleles have lower expression levels of mir-499 and mir-608 than those of major alleles (P < 0.001). These findings indicated that rs3746444 in mir-499 and rs4919510 in mir-608 might play a substantial role in the susceptibility to lung cancer.

Emerging role of NRF2 in chemoresistance by regulating drug-metabolizing enzymes and efflux transporters

Chemoresistance is a disturbing barrier in cancer therapy, which always results in limited therapeutic options and unfavorable prognosis. Nuclear factor E2-related factor 2 (NRF2) controls the expression of genes encoding cytoprotective enzymes and transporters that protect against oxidative stress and electrophilic injury to maintain intrinsic redox homeostasis. However, recent studies have demonstrated that aberrant activation of NRF2 due to genetic and/or epigenetic mutations in tumor contributes to the high expression of phase I and phase II drug-metabolizing enzymes, phase III transporters, and other cytoprotective proteins, which leads to the decreased therapeutic efficacy of anticancer drugs through biotransformation or extrusion during chemotherapy. Therefore, a better understanding of the role of NRF2 in regulation of these enzymes and transporters in tumors is necessary to find new strategies that improve chemotherapeutic efficacy. In this review, we summarized the recent findings about the chemoresistance-promoting role of NRF2, NRF2-regulated phase I and phase II drug-metabolizing enzymes, phase III drug efflux transporters, and other cytoprotective genes. Most importantly, the potential of NRF2 was proposed to counteract drug resistance in cancer treatment.

Case-Control Study on Impact of the Telomerase Reverse Transcriptase Gene Polymorphism and Additional Single Nucleotide Polymorphism (SNP)- SNP Interaction on Non-Small Cell Lung Cancers Risk in Chinese Han Population

AIMS

To investigate the impact of telomerase reverse transcriptase (TERT) gene polymorphism and additional SNP-SNP interaction on non-small cell lung cancer (NSCLC) risk in Chinese population.

METHODS

A total of 828 participants (526 males, 302 females), with a mean age of 71.3 ± 15.7 years old, were selected, including 410 NSCLC patients and 418 normal participants. Logistic regression was performed to investigate association between single nucleotide polymorphism (SNP) and NSCLC risk. Generalized multifactor dimensionality reduction (GMDR) was used to analysis the interaction among four SNPs.

RESULTS

Non-small cell lung cancer risk was significantly higher in carriers of G allele of the rs2736100 polymorphism than those with TT (TG + GG vs. TT, adjusted OR (95%CI = 1.68 (1.28-2.07). In addition, we also found that NSCLC risk was also significantly higher in carriers of A allele of the rs2736098 polymorphism than those with GG (GA + AA vs. GG, adjusted OR (95%CI) = 1.52 (1.19-1.93). GMDR analysis indicated that there was a significant two-locus model (P = 0.0100) involving rs2736098 and rs2736100, indicating a potential gene-gene interaction between rs2736098 and rs2736100. Overall, the two-locus models had a cross-validation consistency of 10 of 10, and had the testing accuracy of 62.17%. We found that patients with GA or AA of rs2736098 and TG or GG of rs2736100 genotype have the highest NSCLC risk, compared to patients with GG of rs2736098 and TT of rs2736100 genotype, OR (95%CI) was 2.52 (1.68-3.68), after covariates adjustment.

CONCLUSIONS

Minor allele of rs2736098 and rs2736100 in TERT gene and interaction between the two SNP were associated with increased risk of NSCLC risk.

Polymorphisms in human telomerase reverse transcriptase (hTERT) gene and susceptibility to gastric cancer in a Turkish population: Hospital-based case-control study

Erosion of telomeres, tandem nucleotide repeats (TTAGGG)n that cap the end of eukaryotic chromosomes, has been related with carcinogenesis. The human telomerase reverse transcriptase (hTERT) gene is encoded the rate-limiting catalytic subunit of the telomerase complexes, which is essential for the protection of telomeric DNA length and chromosomal stability. The purpose of this study was to examine the effect of four functional single nucleotide polymorphisms (SNPs) of hTERT (rs2736109 G>A, rs2735940 T>C, rs2853669 A>G and rs2736100 T>G) on susceptibility to gastric cancer (GC) in Turkish population. The genotype frequency of hTERT rs2736109 G>A, rs2735940 T>C, rs2853669 A>G and rs2736100 T>G polymorphisms were determined by using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and TaqMan methods in 104 subjects with GC and 209 healthy control subjects. We found that hTERT rs2736109 G>A (AA+AG vs. GG OR=1.68 95% CI=1.01-2.81, P=0.04), rs2735940 T>C (CC vs. CT+TT: OR=2.53 95% CI=1.01-6.13, P=0.03), and rs2736100 T>G (TT vs. TG+GG: OR=2.27 95% CI=1.23-4.17, P=0.006) polymorphisms were associated with risk of GC. In the haplotype analysis, hTERT Grs2736109/Trs2735940/Ars2853669/Grs2736100 haplotype was also related with an increased risk of GC (OR=1.75; 95% CI: 1.05-2.93, P=0.03). Because this is the first study regarding the hTERT rs2736109 G>A, rs2735940 T>C, rs2853669 A>G and rs2736100 T>G polymorphisms and the risk of GC susceptibility in the literature, further independent studies are needed to verify our results in a larger sample sizes, as well as in patients of different populations.

The role of oxidative stress on breast cancer development and therapy

Reactive oxygen species (ROS) are produced by both enzymatic and non-enzymatic systems within eukaryotic cells and play important roles in cellular physiology and pathophysiology. Although physiological concentrations are crucial for ensuring cell survival, ROS overproduction is detrimental to cells, and considered key-factors for the development of several diseases, such as neurodegenerative diseases, cardiovascular disorders, and cancer. Cancer cells are usually submitted to higher ROS levels that further stimulate malignant phenotype through stimulus to sustained proliferation, death evasion, angiogenesis, invasiveness, and metastasis. The role of ROS on breast cancer etiology and progression is being progressively elucidated. However, less attention has been given to the development of redox system-targeted strategies for breast cancer therapy. In this review, we address the basic mechanisms of ROS production and scavenging in breast tumor cells, and the emerging possibilities of breast cancer therapies targeting ROS homeostasis.

Telomerase Reverse Transcriptase (TERT) Gene Variations and Susceptibility of Colorectal Cancer

AIM

Colorectal cancer is the third most common cause of cancer-related mortality. Previous studies demonstrated increased telomerase activity in colorectal cancer tissue and suggested a prognostic value for patients with colorectal carcinoma. Telomerase reverse transcriptase (TERT), one of the main functional subunits of the telomerase, is an important factor in modulating telomerase activity, telomere length, and genomic stability. However, there are few studies that have addressed the association between genetic variation at TERT and the risk of colorectal cancer.

METHOD

We evaluated the influence of three common single-nucleotide polymorphisms (SNPs) of the TERT gene (rs2853669, rs2736100, rs2736098) on susceptibility to colorectal cancer in 104 patients and 135 controls in a Turkish population.

RESULTS

We observed that rs2736098 was significantly associated with increased risk of colorectal cancer (OR = 2.53; 95% CI = 1.26-5.10; p = 0.008). On the other hand, rs2736100 and rs2853669 showed no association with colorectal cancer (p ≥ 0.128).

CONCLUSION

These findings are the first results of TERT allele distributions in the Turkish population and also provide increased understanding with respect to colorectal cancer etiology.

TERT Polymorphism rs2853669 Influences on Lung Cancer Risk in the Korean Population

Short telomeres are known as one of the risk factors for human cancers. The present study was conducted to evaluate the association between 6 polymorphisms, which were related with short telomere length in the Korean population, and lung cancer risk using 1,100 cases and 1,096 controls. Among the 6 polymorphisms, TERT rs2853669 was significantly associated with increased lung cancer risk under a recessive model (odds ratio [OR]=1.38, 95% confidence interval [CI]=1.05-1.81, P=0.02). The effect of rs2853669 on lung cancer risk was significant in younger individuals (OR=1.73, 95% CI=1.18-2.54, P=0.005) and adenocarcinoma (OR=1.50, 95% CI=1.07-2.07, P=0.02). Our results suggest that a common functional promoter polymorphism, TERT rs2853669, may influence both telomere length and lung cancer risk in the Korean population.

Association between TERT promoter polymorphisms and acute myeloid leukemia risk and prognosis

Telomerase reverse transcriptase gene (TERT) promoter mutations are identified in many malignancies but not in hematological malignancies. Here we analyzed TERT and protection of telomeres 1 gene (POT1) mutations, and four different TERT SNVs in 226 acute myeloid leukemia (AML) patients and 806 healthy individuals in a case referent design, where also overall survival was assessed. A significant association for increased risk of AML was found for TERT SNVs, rs2853669 (OR = 2.45, p = 0.00015) and rs2736100 (OR = 1.5, p = 0.03). The overall survival for patients with CC genotype of rs2853669 was significantly shorter compared to those with TT or TC genotypes (p = 0.036 and 0.029 respectively). The influence of TERT rs2853669 CC on survival was confirmed in multivariable Cox regression analysis as an independent risk biomarker in addition to high risk group, higher age and treatment. No hot spot TERT promoter mutations at -228C > T or -250C > T or POT1 mutations could be identified in this AML cohort. We show that rs2853669 CC may be a risk factor for the development of AML that may also be used as a prognostic marker to identify high risk normal karyotype-AML (NK-AML) patients, for treatment guidance.

Identification of a Potential Regulatory Variant for Colorectal Cancer Risk Mapping to Chromosome 5q31.1: A Post-GWAS Study

Large-scale genome-wide association studies (GWAS) have established chromosome 5q31.1 as a susceptibility locus for colorectal cancer (CRC), which was still lack of causal genetic variants. We searched potentially regulatory single nucleotide polymorphisms (SNPs) in the overlap region between linkage disequilibrium (LD) block of 5q31.1 and regulatory elements predicted by histone modifications, then tested their association with CRC via a case-control study. Among three candidate common variants, we found rs17716310 conferred significantly (heterozygous model: OR = 1.273, 95% confidence interval (95%CI) = 1.016–1.595, P = 0.036) and marginally (dominant model: OR = 1.238, 95%CI = 1.000–1.532, P = 0.050) increase risk for CRC in a Chinese population including 695 cases and 709 controls. This variation was suggested to be regulatory altering the activity of enhancer that control PITX1 expression. Using epigenetic information such as chromatin immunoprecipitation-sequencing (ChIP-seq) data might help researchers to interpret the results of GWAS and locate causal variants for diseases in post-GWAS era.

The Association between Telomere Length and Cancer Prognosis: Evidence from a Meta-Analysis

BACKGROUND

Telomeres are essential for chromosomal integrity and stability. Shortened telomere length (TL) has been associated with risk of cancers and aging-related diseases. Several studies have explored associations between TL and cancer prognosis, but the results are conflicting.

METHODS

Prospective studies on the relationship between TL and cancer survival were identified by a search of PubMed up to May 25, 2015. There were no restrictions on the cancer type or DNA source. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. Meta-analysis approaches were conducted to determine pooled relative risks and 95% confidence intervals.

RESULTS

Thirty-three articles containing forty-five independent studies were ultimately involved in our meta-analysis, of which twenty-seven were about overall cancer survival and eighteen were about cancer progression. Short TL was associated with increased cancer mortality risk (RR = 1.30, 95%CI: 1.06-1.59) and poor cancer progression (RR = 1.44, 95%CI: 1.10-1.88), both with high levels of heterogeneity (I2 = 83.5%, P = 0.012for overall survival and I2 = 75.4%, P = 0.008 for progression). TL was an independent predictor of overall cancer survival and progression in chronic lymphocytic leukemia. Besides, short telomeres were also associated with increased colorectal cancer mortality and decreased overall survival of esophageal cancer, but not in other cancers. Cancer progression was associated with TL in Asian and America populations and short TL predicted poor cancer survival in older populations. Compared with tumor tissue cells, TL in blood lymphocyte cells was better for prediction. In addition, the associations remained significant when restricted to studies with adjustments for age, with larger sample sizes, measuring TL using southern blotting or estimating risk effects by hazard ratios.

CONCLUSION

Short TL demonstrated a significant association with poor cancer survival, suggesting the potential prognostic significance of TL. Additional large well-designed studies are needed to confirm our findings.

The Associations between RNA Splicing Complex Gene SF3A1 Polymorphisms and Colorectal Cancer Risk in a Chinese Population

BACKGROUND

Aberrant alternative splicing included alterations in components of the mRNA splicing machinery often occurred in colon cancer. However, the role of SF3A1, one key component of the mRNA splicing machinery, on colorectal cancer (CRC) risk was still not elucidated.

METHOD AND FINDINGS

We performed a hospital-based case-control study containing 801 CRC patients and 817 cancer-free controls to examine the association between SF3A1 polymorphisms and CRC risk in a Chinese population. Four candidate SNPs (rs10376, rs5753073, rs2839998 and rs2074733) were selected based on bioinformatics analysis and previous findings. The results showed no significant associations between these SNPs and CRC risk (P > 0.05). Besides, the stratified analysis based on the smoking and alcohol use status obtained no statistically significant results.

CONCLUSION

Our study was the first one to investigate the association between SF3A1 polymorphisms and CRC risk. The results suggested these four SNPs in SF3A1 were not associated with CRC risk in a Chinese population, however, further more studies are needed to confirm our findings.

Expression level of hTERT is regulated by somatic mutation and common single nucleotide polymorphism at promoter region in glioblastoma

We investigated the role of somatic mutations and a common single nucleotide polymorphism (SNP) in the hTERT promoter region on hTERT expression and clinical outcomes. The hTERT promoter region was sequenced from 48 glioblastomas. hTERT expression was analyzed by quantitative real time-PCR. The association between hTERT promoter genetic changes and other genomic events and clinical variables common in gliomas were examined. C228T and C250T somatic mutations were found in 60.4% of glioblastomas, and a common SNP (T349C) was found in 66.6%. Somatic mutations and the SNP likely have opposing effects on hTERT expression. hTERT expression was significantly higher in the C228T or C250T mutated tumors. Tumors with the T349C genotype showed lower hTERT expression when C228T or C250T mutations were present. However, no significant survival differences were observed among the groups with or without hTERT promoter mutations and SNP. There was a significant association between genetic changes in the hTERT promoter and patient age as well as MGMT promoter methylation and EGFR amplification. hTERT expression is modulated by somatic mutations in the hTERT promoter as well as a common polymorphism. However, hTERT related genomic changes have limited value as an independent prognostic factor for clinical outcomes in glioblastomas.

Genetic variations in TERT-CLPTM1L genes and risk of lung cancer in a Chinese population

The objective of the present study was to analyze the relationship between genetic polymorphisms of the rs2736098 locus of the telomerase reverse transcriptase (TERT) gene and the rs401681 locus of the cleft lip and palate transmembrane protein 1 (CLPTM1L) gene and the risk of developing lung cancer in males in Jinzhou. A total of 214 lung cancer patients who were admitted in Jinzhou Medical University were analyzed, and 216 healthy males were selected as controls. Venous blood from all subjects and data on relevant risk factors were collected. DNA was extracted from peripheral blood by the phenol-chloroform method. Real-time fluorescent quantitative PCR (TaqMan real-time PCR) was used for DNA amplification. The genotyping results of the genetic polymorphisms of the TERT rs2736098 and CLPTM1L rs401681 loci were detected. The risk of developing lung cancer in the population with the TERT rs2736098 locus carrying the T allele was 1.614 times that with the TERT rs2736098 locus carrying the C allele after adjustment of the age factor. The risk of developing lung cancer in the population carrying the TT mutant genotype and the CT genotype increased significantly compared with that carrying the CC wild genotype [odds ratio (OR)=1.815, 95% CI=1.132–2.957; OR=2.417, 95% CI=1.158–4.943]. Based on a comparison between the combination of the two mutant genotypes (CT+TT) and the wild homozygous genotype (CC), the mutant genotype increased the risk of developing lung cancer (OR=1.955, 95% CI=1.213–3.157). The risk of developing lung cancer in the population with the CLPTM1L rs401681 locus carrying the T allele was 1.399 times that carrying the C allele (OR=1.343, 95% CI=1.035–1.978). The population with the TERT rs2736098 locus carrying the mutant genotype (CT+TT) was associated with the number of tumors (OR=0.553, 95% CI=0.236–0.928). In conclusion, in males, the TERT rs2736098 and CLPTM1L rs401681 T alleles are the susceptibility factors for developing lung cancer. Individuals, including the smoking population, who carry both the TERT rs2736098 and CLPTM1L rs401681 T alleles are more likely to develop lung cancer.

CLPTM1L genetic polymorphisms and interaction with smoking and alcohol drinking in lung cancer risk: a case-control study in the Han population from northwest China

Genetic variants of cleft lip and palate trans-membrane 1-like (CLPTM1L) genes in the p15.33 region of chromosome 5 were previously identified to influence susceptibility to lung cancer. We examined the association of single nucleotide polymorphisms (SNPs) in CLPTM1L genes with lung cancer and explored their potential effects on the relationship between environmental risk factors (smoking, drinking) and lung cancer in a Chinese Han population. We genotyped 9 single nucleotide polymorphisms (SNPs) of CLPTM1L in a case-control study with 228 lung cancer cases and 301 controls from northwest China. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression. We identified that the minor alleles of rs451360, rs402710, and rs31484 in CLPTM1L were associated with a 0.52-fold, 0.76-fold, and 0.70-fold decreased risk of lung cancer in allelic model analysis, respectively. In the genetic model analysis, we found rs402710 and rs401681 were associated with decreased lung cancer risk. Further stratification analysis showed that rs380286 displayed a significantly decreased lung cancer risk (OR=0.65, P=0.041) in the non-drinkers. In addition, Haplotype "GTTATCTGT" was found to be associated with decreased lung cancer risk (OR=0.50, P=0.033). Our results verified that genetic variants of CLPTM1L contribute to lung cancer susceptibility in the northwest Chinese Han population. Additionally, we found that consumption of alcohol may interact with CLPTM1L polymorphisms to contribute to overall lung cancer susceptibility.

Integrative genomic analysis identifies that SERPINA6-rs1998056 regulated by FOXA/ERα is associated with female hepatocellular carcinoma

The human forkhead box A1 (FOXA1) and A2 (FOXA2) transcription factors have been found to control estrogen and androgen signaling through co-regulating target genes with sex hormone receptors. Here we used an integrative strategy to examine the hypothesis that genetic variants at FOXA1/2 binding elements may be associated with sexual dimorphism of hepatocellular carcinoma (HCC) risk. Firstly we extracted chromatin immunoprecipitation-sequencing (ChIP-seq) data of FOXA1, FOXA2 and estrogen receptor 1(ERα) from ENCODE database to obtain dual target regions of FOXA/ERα, and further intersected these regions with genes' promoters. Then we used MATCH program to predict FOXA binding elements, in which genetic variants were retrieved by dbSNP database (NCBI, build 134). A total of 15 candidate variants were identified in this stage. Secondly we performed a case-control study with 1,081 HCC patients and 2,008 matched controls and found a significant association of SERPINA6-rs1998056 with female HCC risk under common genetic models (e.g. GG versus CC: OR = 2.03, 95% CI = 1.26-3.27, P = 0.004). Moreover, results from our real-time quantitative polymerase chain reaction (qPCR) using 72 normal liver tissues adjacent to the tumors showed that SERPINA6 expression was significantly different among different genotypes of this variant (GG versus CC: P = 0.032; Group test: P = 0.060). In summary, our study suggested that SERPINA6-rs1998056 regulated by FOXA/ERα might be associated with female HCC risk.

Increased lung cancer risk associated with the TERT rs2736100 polymorphism: an updated meta-analysis

The rs2736100 polymorphism in the telomerase reverse transcriptase (TERT) gene has been implicated in lung cancer risk in multiple populations, but the existing evidence lacks statistical power to draw a convincing conclusion. Therefore, the present study was devised to derive a more precise estimation of the association between rs2736100 and lung cancer risk. The PubMed, Embase, and Web of Science databases were comprehensively searched for papers concerning lung cancer risk in relation to rs2736100. Pooled odds ratios (ORs) and the 95 % confidence intervals (CIs) were appropriately calculated using the fixed or random effects model. Meta-analysis of 20 independent studies involving 39,715 cancer cases and 61,462 control subjects showed statistical evidence for an association between rs2736100 and increased risk of lung cancer. Subgroup analysis by ethnicity demonstrated a significant association among both Asian and Caucasian populations. We additionally found an increased risk of non-small cell lung cancer and lung adenocarcinoma strongly associated with rs2736100. These data provide further evidence supporting a role for genetic susceptibility of TERT rs2736100 in the development of lung cancer.

Genetic variant in SWI/SNF complexes influences hepatocellular carcinoma risk: a new clue for the contribution of chromatin remodeling in carcinogenesis

Chromatin remodeling has been newly established as an important cancer genome characterization and recent exome and whole-genome sequencing studies of hepatocellular carcinoma (HCC) showed that recurrent inactivating mutations in SWI/SNF subunits involved in the molecular basis of hepatocarcinogenesis. To test the hypothesis that genetic variants in the key subunits of SWI/SNF complexes may contribute to HCC susceptibility, we systematically assessed associations of genetic variants in SWI/SNF complexes with HCC risk using a two-staged case-control study in Chinese population. A set of 24 single nucleotide polymorphisms (SNPs) in SWI/SNF complexes were examined in stage 1 with 502 HCC patients and 487 controls and three promising SNPs (SMARCA4 rs11879293, rs2072382 and SMARCB1 rs2267032) were further genotyped in stage 2 comprising 501 cases and 545 controls for validation. SMARCA4 rs11879293 presented consistently significant associations with the risk of HCC at both stages, with an OR of 0.73 (95% CI: 0.62–0.87) using additive model in combined analysis. Moreover, the decreased risk of HCC associated with SMARCA4 rs11879293 AG/AA was more evident among HBsAg positive individuals (OR = 0.47, 95% CI: 0.27–0.80) in combined analysis. The study highlighted the potential role of the SWI/SNF complexes in conferring susceptibility to HCC, especially modified HCC risk by HBV infection.

A genome-wide association study identifies a locus on TERT for mean telomere length in Han Chinese

Leukocyte telomere length (LTL) is a predictor of aging and a number of age-related diseases. We performed genome-wide association studies of mean LTL in 2632 individuals,with a two-stage replication in 3917 individuals from Chinese populations. To further validate our findings, we get the results of 696 samples from a cohort of European ancestry. We identified two loci associated with LTL that map in telomerase reverse transcriptase (TERT; rs2736100, P = 1.93×10⁻⁵) on chromosome 5p15.33 and near keratin 80 (KRT80; rs17653722, P = 6.96×10⁻⁶) on 12q13.13. In Chinese population each C allele of rs2736100 and T allele of rs17653722 was associated with a longer mean telomere length of 0.026 and 0.059 T/S, respectively, equivalent to about 3 and 7 years of average age-related telomere attrition. Our findings provide new insights into telomere regulatory mechanism and even pathogenesis of age-related diseases.

Telomeres in molecular epidemiology studies

Telomeres are long nucleotide repeats and protein complexes at the ends of chromosomes that are essential for maintaining chromosomal stability. They shorten with each cell division, and therefore, telomere length is a marker for cellular aging and senescence. Epidemiological research of telomeres investigates the role that these genetic structures have in disease risk and mortality in human populations. This chapter provides an overview of the current telomere epidemiology research and discusses approaches taken in these investigations. We also highlight important methodological considerations that may affect data interpretation.

Association between MCP-1 -2518A/G polymorphism and cancer risk: evidence from 19 case-control studies

Background

Single nucleotide polymorphisms (SNPs) may affect the development of diseases. The -2518A/G polymorphism in the regulatory region of the monocyte chemo-attractant protein-1 (MCP-1) gene has been reported to be associated with cancer risk. However, the results of previous studies were inconsistent. Therefore, we performed a meta-analysis to obtain a more precise estimation of the relationship between the -2518A/G polymorphism and cancer risk.

Methodology/Principal Findings

We performed a meta-analysis, including 4,162 cases and 5,173 controls, to evaluate the strength of the association between the −2518A/G polymorphism and cancer risk. Odds ratio (OR) and 95% confidence intervals (95% CIs) were used to assess the strength of association. Overall, the results indicated that the −2518A/G polymorphism was not statistically associated with cancer risk. However, sub-group analysis revealed that individuals with GG genotypes showed an increased risk of cancer in digestive system compared with carriers of the A allele (GG vs. AA: OR = 1.43, 95%CI = 1.05–1.96, P_{heterogeneity} = 0.08; GG vs. AG/AA: OR = 1.29, 95%CI = 1.02–1.64, P_{heterogeneity} = 0.14). In addition, the increased risk of GG genotype was also observed in Caucasians (GG vs. AG/AA: OR = 1.81, 95%CI = 1.10–2.96, P_{heterogeneity} = 0.02).

Conclusion

This meta-analysis suggests that the MCP-1 −2518A/G polymorphism may have some relation to digestive system cancer susceptibility or cancer development in Caucasian. Large-scale and well-designed case-control studies are needed to validate the findings.