A tandem repeat of human telomerase reverse transcriptase (hTERT) and risk of breast cancer development and metastasis in Chinese women

MNS16A polymorphism of the TERT gene on cancer risk: a systematic review and meta-analysis

Some studies have suggested that MNS16A polymorphism in telomerase reverse transcriptase (TERT) gene is associated with cancer risk in various populations and types of cancer. However, the results of previous studies exploring this link have been inconclusive. To be able to accurately assess the association between TERT MNS16A polymorphism and cancer risk, we performed a meta-analysis based on 17 studies described in 12 articles, including 13,764 controls and 7,132 cases. Combined odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were estimated to assess the strength of the association in either a fixed-effects model or, if applicable, a random-effects model. Heterogeneity between articles and their publication bias were also tested. Overall, pooled results showed that no significant association between this polymorphism and cancer was found in the five gene models tested.Considering that there may be too many negative studies in the included studies, diluting the results of the total sample size, we stratified these studies according to ethnicity, source of controls and cancer type. In the stratified analysis, a statistically significant association was observed between Asians and population-based studies. We also analyzed by cancer type and found a significantly increased risk of brain cancer in five genetic models. Our results suggest that TERT MNS16A polymorphism is likely to contribute to increased cancer risk.

The role of NF-κB in breast cancer initiation, growth, metastasis, and resistance to chemotherapy

Breast cancer (BC) is the second most fatal disease and is the prime cause of cancer allied female deaths. BC is caused by aberrant tumor suppressor genes and oncogenes regulated by transcription factors (TFs) like NF-κB. NF-κB is a pro-inflammatory TF that crucially alters the expressions of various genes associated with inflammation, cell progression, metastasis, and apoptosis and modulates a network of genes that underlie tumorigenesis. Herein, we focus on NF-κB signaling pathways, its regulators, and the rationale for targeting NF-κB. This review also includes TFs that maintain NF-κB crosstalk and their roles in promoting angiogenesis and metastasis. In addition, we discuss the importance of combination therapies, resistance to treatment, and potential novel therapeutic strategies including nanomedicine that targets NF-κB.

Variable number tandem repeats (VNTRs) as modifiers of breast cancer risk in carriers of BRCA1 185delAG

Despite substantial efforts in identifying both rare and common variants affecting disease risk, in the majority of diseases, a large proportion of unexplained genetic risk remains. We propose that variable number tandem repeats (VNTRs) may explain a proportion of the missing genetic risk. Herein, in a pilot study with a retrospective cohort design, we tested whether VNTRs are causal modifiers of breast cancer risk in 347 female carriers of the BRCA1 185delAG pathogenic variant, an important group given their high risk of developing breast cancer. We performed targeted-capture to sequence VNTRs, called genotypes with adVNTR, tested the association of VNTRs and breast cancer risk using Cox regression models, and estimated the effect size using a retrospective likelihood approach. Of 303 VNTRs that passed quality control checks, 4 VNTRs were significantly associated with risk to develop breast cancer at false discovery rate [FDR] < 0.05 and an additional 4 VNTRs had FDR < 0.25. After determining the specific risk alleles, there was a significantly earlier age at diagnosis of breast cancer in carriers of the risk alleles compared to those without the risk alleles for seven of eight VNTRs. One example is a VNTR in exon 2 of LINC01973 with a per-allele hazard ratio of 1.58 (1.07-2.33) and 5.28 (2.79-9.99) for the homozygous risk-allele genotype. Results from this first systematic study of VNTRs demonstrate that VNTRs may explain a proportion of the unexplained genetic risk for breast cancer.

Analysis of MNS16A VNTR polymorphic sequence variations of the TERT gene and associated risk for development of bladder cancer

Background:

The MNS16A variable number tandem repeat (VNTR) polymorphism of the human telomerase reverse transcriptase (hTERT) gene acts as a regulator of hTERT promoter activity and has been shown to have a role in the predisposition toward various cancers. The current study aimed to investigate the association between MNS16A VNTR alleles and genetic predisposition to bladder cancer in the Kashmir region of northern India.

Materials and methods:

A total of 130 patients with bladder cancer and 170 age- and gender-matched healthy controls were included in this study. Primer-specific polymerase chain reaction was used to genotype the different variants of VNTR alleles of the MNS16A VNTR polymorphism.

Results:

Short allele VNTR-243 (SS) genotype frequency significantly differed between cases (9.23%) and controls (3.52%) (OR = 3.08 [95% CI = 1.10–8.61], p = 0.042). The VNTR-243 short allele (S) was found significantly more frequent in bladder cancer cases (28.46%) than controls (20.88%) (OR = 1.50 [95% CI = 1.03–2.19], p = 0.034). Likewise, the long allele (LL) hTERT MNS16A genotype was distributed more frequently in low stage disease versus high stage disease (60.29% vs. 39.70%) (OR = 0.79 [95% CI = 0.39–1.60], p = 0.595).

Conclusion:

The MNS16A VNTR short allele (S) was associated with a higher risk for bladder cancer in our population as compared to long alleles.

MNS16A VNTR polymorphism of human telomerase gene: Elucidation of a gender specific potential allele associated with type 2 diabetes in Bangladeshi population

BACKGROUND

Type 2 diabetes (T2D) is a multifactorial disorder that affects multi-organ and can alter telomerase (encoded by hTERT gene) activity and thus, may affect telomere length. The variable number of tandem repeats MNS16A in hTERT gene facilitates extension of telomeres by regulating telomerase. In the present study, genetic analysis of MNS16A tandem repeats in hTERT gene was performed with the aim of finding out any association of allelic and genotypic variations with the risk of T2D in Bangladeshi population.

METHODS

A total of unrelated 395 individuals with T2D and 247 healthy individuals were included in the study. The genotypic and allelic frequencies were determined using allele specific polymerase chain reaction. The association of allelic and genotypic frequencies with risk of T2D was analyzed using logistic regression analysis on the basis of odds ratio at 95% confidence interval. Hardy-Weinberg equilibrium (HWE) test was performed to evaluate the uniformity of the genotypic frequencies and deviation from the HWE was tested using Chi-square test.

RESULTS

Logistic regression analyses revealed significant association of short allele containing 243 bp (OR: 1.37 and p = 0.03) with T2D, when the long alleles (commonly found) were considered as reference. The heterozygous genotype 272/302 was significantly associated with the decreased risk of T2D (OR: 0.33, p = 0.001). The combined results of genotypes indicated that the MNS16A polymorphism was significantly associated with the increased risk of T2D under the dominant model (LL vs SL + SS; OR: 2.62, p < 0.0001). Interestingly, short allele 243 was associated with the risk of disease only in male population (OR: 1.62, p = 0.02). The genotype 272/302 was also found to be associated with the decreased risk of T2D when respective data for male was analyzed individually.

CONCLUSIONS

We have identified four variable number of tandem repeats with varying patterns of association with T2D in Bangladeshi population and to extend our knowledge of understanding regarding these VNTRs, further large-scale studies are warranted.

The MNS16A VNTR polymorphism of the TERT gene in bladder cancer

OBJECTIVE

Bladder cancer (BC) is a complex disease that has a high morbidity rate. The MNS16A polymorphism in the TERT gene has been indicated to play a role in the presence of various cancer types and multiple tumor populations. In the present study, our goal was to investigate whether the MNS16A (VNTRs) in the TERT gene was associated with bladder cancer.

MATERIAL AND METHODS

A total of 70 patients with BC and 120 normal controls were included in the study. The MNS16A (VNTRs) in the TERT gene was amplified using polymerase chain reaction (PCR). The PCR products were visualized on 3% high resolution agarose gel and under a UV light.

RESULTS

The MNS16A VNTR-302 allele was found to be the most common allele in both, the patient group (64%) and the control group (62%). The second most common allele was the VNTR-243 allele that occurred at a frequency of around 34% in BC patients and 33% in the controls. VNTR-333 (patient group, 1%; control group, 3%) and VNTR-274 (patient group, 2%; control group, 1%) alleles were reported as the least common alleles in this study.

CONCLUSION

When comparing the frequencies of genetic variants between cases and controls, we observed that our findings did not support the hypothesis that the MNS16A VNTR polymorphism of the TERT gene might regulate cancer susceptibility.

Association of CDH1 and TERT Single-Nucleotide Polymorphisms with Susceptibility to Familial Breast Cancer Risk

Breast cancer (BC) is a multistep disease that is thought to result from an interaction between genetic background and environmental factors. In Iran, one of the strongest risk factors for developing BC is a positive family history of the disease. Recently, various polymorphisms of E-cadherin (CDH1) and TERT have been found to be associated with increased BC risk worldwide. This study aimed to analyze the association of CDH1 and TERT single-nucleotide polymorphisms with susceptibility to familial BC (FBC) risk in the Iranian patients. One hundred five patients with FBC and 110 non-FBC (NFBC) were genotyped to elucidate the potential association between CDH1 rs5030625 polymorphism and TERT rs2736098 polymorphism by polymerase chain reaction-restriction fragment length polymorphism. Then, results were evaluated by electrophoresis and Epi Info(™) 2012 software. A significant association was found between CDH1 rs5030625 GAGA genotype and FBC risk. Compared with the control group, the FBC patients had a lower frequency of GG genotype (69% vs. 85%) and a higher frequency of GAGA (5% vs. 2%, P < 0.02). Furthermore, the patients with FBC had a lower frequency of TERT rs2736098 GG genotype (38% vs. 49%, P = 0.001) and a higher frequency of rs2736098 AA genotype (12% vs. 5%, P = 0.001) compared with the NFBC. In contrast, the TERT rs2736098 GG genotype potentially increased the recurring risk of FBC (odds ratio = 3.17, P < 0.01). Allele genotypic frequencies in the FBC patients differed from those of the controls. Interestingly, tumors in FBC patients with rs2736098 GG genotype and rs5030625 GAGA exhibited higher mitotic activity, higher grade, lower estrogen receptor, and progesterone receptor than the other genotypes. In conclusion, CDH1 rs5030625 GAGA genotype and TERT rs2736098 GG genotype in combination with clinical parameters may be prognostic factors rather than susceptibility factors during the progression of FBC.

Association of MNS16A VNTR and hTERT rs2736098: G>A polymorphisms with susceptibility to diffuse large B-cell lymphoma

PURPOSE

Genetic studies of diffuse large B-cell lymphoma (DLBCL) may serve to clarify disease pathogenesis and mark at-risk populations. Evidence of long telomeres and high telomerase activity have been demonstrated in DLBCL. We aimed to examine human telomerase gene ( hTERT) MNS16A variable number of tandem repeats and hTERT rs2736098: G>A polymorphisms in relation to DLBCL susceptibility.

METHODS

In a case control study, 71 patients with DLBCL and 156 controls were genotyped for MNS16A using polymerase chain reaction and hTERT rs2736098: G>A using polymerase chain reaction restriction fragment length polymorphism.

RESULTS

In both codominant and recessive models, there was a significant difference in the distribution of MNS16A genotypes between patients with DLBCL and controls (p = 0.047 and p = 0.018, respectively). In both models, carriers of S/S genotype were at higher risk to develop DLBCL (odds ratio [OR] 2.51, 95% confidence interval [CI] 1.19-5.29 and OR 2.19, 95% CI 1.15-4.17, respectively). In the log-additive model, each copy of S allele significantly increased DLBCL risk in an additive form (p = 0.018, OR 1.57, 95% CI 1.08-2.29). The frequency distribution of MNS16A S alleles was significantly higher in patients than controls (p = 0.012). Carriers of S alleles were at higher risk to develop DLBCL than carriers of L alleles (OR 1.67, 95% CI 1.12-2.49). hTERT rs2736098: G>A genotype distribution did not differ significantly between patients with DLBCL and controls.

CONCLUSIONS

MNS16A genetic variations are associated with DLBCL susceptibility.

MNS16A tandem repeat minisatellite of human telomerase gene: functional studies in colorectal, lung and prostate cancer

MNS16A, a functional polymorphic tandem repeat minisatellite, is located in the promoter region of an antisense transcript of the human telomerase reverse transcriptase gene. MNS16A promoter activity depends on the variable number of tandem repeats (VNTR) presenting varying numbers of transcription factor binding sites for GATA binding protein 1. Although MNS16A has been investigated in multiple cancer epidemiology studies with incongruent findings, functional data of only two VNTRs (VNTR-243 and VNTR-302) were available thus far, linking the shorter VNTR to higher promoter activity.

For the first time, we investigated promoter activity of all six VNTRs of MNS16A in cell lines of colorectal, lung and prostate cancer using Luciferase reporter assay. In all investigated cell lines shorter VNTRs showed higher promoter activity. While this anticipated indirect linear relationship was affirmed for colorectal cancer SW480 (P = 0.006), a piecewise linear regression model provided significantly better model fit in lung cancer A-427 (P = 6.9 × 10⁻⁹) and prostate cancer LNCaP (P = 0.039). In silico search for transcription factor binding sites in MNS16A core repeat element suggested a higher degree of complexity involving X-box binding protein 1, general transcription factor II–I, and glucocorticoid receptor alpha in addition to GATA binding protein 1.

Further functional studies in additional cancers are requested to extend our knowledge of MNS16A functionality uncovering potential cancer type-specific differences. Risk alleles may vary in different malignancies and their determination in vitro could be relevant for interpretation of genotype data.

Association of human telomerase reverse transcriptase gene polymorphisms, serum levels, and telomere length with renal cell carcinoma risk and pathology

Human telomerase reverse transcriptase (hTERT) is the catalytic subunit of the human telomerase and plays a key role in telomere restitution and gene regulation. Evidence suggests that hTERT is linked with the risk and progression of several malignancies, but there are no comprehensive data in renal cell carcinoma (RCC). In this case-control study, we assessed seven polymorphic hTERT gene variants (MNS16A, rs2736100, rs2736098, rs7726159, rs2853677, rs13172201, and rs10069690), hTERT serum levels, and the telomere length of 663 individuals, including 243 with clear cell RCC and 420 age- and gender-matched healthy controls. The SL and SS genotypes of MNS16A were associated with a decreased risk for RCC on the multivariable logistic regression analysis (SL-OR 0.72, SS-OR 0.37, P < 0.001). The GG genotype of rs2736098 was associated with a decreased risk for RCC compared with AA (OR 0.18, P < 0.001). Both telomere length and hTERT serum levels increased with every G allele in rs2736098 (P = 0.008). Pretherapeutic hTERT serum levels were higher in patients with advanced tumor stages (P = 0.037) and distant metastases (P = 0.006). Rs2736100, rs7726159, rs2853677, rs13172201, and rs10069690 were not linked with RCC risk, and none of the polymorphisms was associated with RCC pathology. In conclusion, the polymorphic number of tandem repeats in hTERT (MNS16A) and rs2736098 may be linked with the risk for RCC. Rs2736098 may have an important role in telomere length restitution and serum hTERT levels may represent a novel biomarker for RCC. © 2015 Wiley Periodicals, Inc.

Role of the functional MNS16A VNTR-243 variant of the human telomerase reverse transcriptase gene in progression and response to therapy of patients with non-Hodgkin's B-cell lymphomas

MNS16A is a functional polymorphic tandem repeat within the human telomerase reverse transcriptase (hTERT) gene. To investigate whether any of the MNS16A repeats represents a genetic risk factor for NHL susceptibility, progression of or response to therapy in 75 patients with non-Hodgkin's lymphomas (NHLs) and 126 healthy individuals were genotyped using the PCR-VNTR technique. A slightly higher frequency of the MNS16A VNTR-243 variant was detected among patients who did not respond to treatment (NR) as compared to patients with complete or partial remission (0.83 vs. 0.51, P = 0.055). NR patients more frequently developed aggressive than indolent type of the disease (0.92 vs. 0.41, P = 0.001). The VNTR-243 allele was more frequently detected among patients with an intermediate-high/high International Prognostic Index (IPI 3-4) score (P = 0.063), especially in patients with advanced age and IPI 3-4 (P = 0.040). In multivariate analysis, higher IPI 3-4 score (OR = 11.364, P = 0.051) and aggressive type of the disease (OR = 18.182, P = 0.012) were found to be independent genetic markers associated with nonresponse to treatment. Presence of the MNS16A VNTR-243 variant also strongly tended to affect the risk of a less favourable response to therapy and was more frequently present among nonresponders (OR = 5.848, P = 0.059). Genetic variation within the hTERT gene may affect the progression and treatment of lymphoproliferative disorders.

Association between hTERT polymorphisms and the risk of breast cancer in a sample of Southeast Iranian population

BACKGROUND

Breast cancer (BC) is considered to be one of the most important causes of death worldwide, and it affects the Iranian female population a decade earlier than female in other parts of the world. Human telomerase reverse transcriptase (hTERT) is a main subunit of the telomerase complex. MNS16A is located downstream of the hTERT gene and is recognized as the regulator of hTERT promoter activity. The aim of the present study was to access the possible impact of hTERT variants on BC risk in an Iranian population in southeast Iran.

METHODS

A total of 491 subjects including 266 BC patients and 225 healthy women participated in the study. Polymerase chain reaction (PCR) was used to genotype the MNS16A variable number of tandem repeats and 177 bp ins/del polymorphisms in the hTERT gene. PCR-RFLP and ARMS-PCR were used to genotype hTERT rs2736098 and 2735940, respectively. The association between genotypes and BC was assessed by computing the odds ratio (OR) and 95% confidence intervals (95% CI) from logistic regression analyses. A p-value of <0.05 was considered statistically significant.

RESULTS

The MNS16A genotype frequency distribution in BC patients was: LL, 43.2%; LS, 51.1%; and SS, 5.7%, and in controls: LL, 29.5%; LS, 68.3%; and SS, 2.2%. The LS genotype decreased the risk of BC compared with LL (OR=0.51, 95% CI=0.35-0.75, p<0.001). The hTERT 177 bp ins/del polymorphism was not polymorphic in our population. All subjects had the ins/ins genotype. Our findings indicate that the MNS16A genotype and hTERT rs2736098 variant were associated with BC risk in the study. We also showed that the rs2736098 A/G polymorphism increased the risk of BC (OR=1.80, 95% CI=1.12-2.88, p=0.017, AG vs AA; OR=1.80, 95% CI=1.06-3.06, p=0.033, GG vs AA; OR=1.87, 95% CI=1.19-2.94, p=0.006, AG+GG vs AA). No significant association was found between the rs2735940 C/T variant and BC.

CONCLUSION

Our findings indicate that the MNS16A genotype and the hTERT rs2736098 variant influence the risk of BC in an Iranian population in southeast Iran.

The MNS16A polymorphism in the TERT gene in peri-centenarians from the Han Chinese population

MNS16A, a variable number of tandem repeats polymorphism in the TERT gene, has been suggested to regulate telomerase activity. As telomerase activity has been reported to be related to life-span, we hypothesized that this polymorphism might affect human longevity by controlling the length of the telomere. To test this hypothesis, we collected 446 unrelated pericentenarian individuals (age[Symbol: see text]90, mean 94.45±3.45 years) and 332 normal controls (age 22-53, mean 35.0±12.0 years) from Dujiangyan, Sichuan, China. We typed the MNS16A polymorphism in both groups, and compared the allele and genotype frequencies between the peri-centenarian and control groups using the chi-squared test. There was no significant difference between the peri-centenarian and control groups. Thus, the MNS16A polymorphism in TERT might not influence human life-span, at least in the Han Chinese population studied here.

MNS16A tandem repeats minisatellite of human telomerase gene and cancer risk: a meta-analysis

Background

Researchers have provided evidence that telomere dysfunction play an important role in cancer development. MNS16A is a polymorphic tandem repeats minisatellite of human telomerase (hTERT) gene that influences promoter activity of hTERT and thus implicates to relate with risk of several malignancies. However, results on association between MNS16A and cancer risk remain controversial. We therefore conduct a meta-analysis to derive a more precise estimation of association between MNS16A and cancer risk.

Methods

A systematic literature search was conducted by searching PubMed, ISI Web of Knowledge, Human Genome and Epidemiology Network Navigator and Google Scholar digital database for publications on associations between MNS16A and cancer risk. Variants with statistically significant associations by meta-analysis were assessed using Venice criteria.

Results

10 case-control articles enrolling 6101 cases and 10521 controls were brought into our meta-analysis. The relationships were strong epidemiological credibility in cerebral cancer and breast cancer population (P for heterogeneity > 0.1). The cumulative analysis in chronologic order suggested a clear tendency towards a significant association with additional study samples.

Conclusions

The results provided a more accurate depiction of the role of MNS16A in cerebral cancer and breast cancer susceptibility. Additional larger studies were warranted to validate our findings.

The functional VNTR MNS16A of the TERT gene is associated with human longevity in a population of Central Italy

BACKGROUND

Telomerase, encoded by TERT, is the ribonucleoprotein polymerase that maintains telomere ends and it plays a crucial role in cellular senescence. TERT single nucleotide polymorphisms (SNPs) have been associated both with various malignancies and telomere length (TL). The association of TERT SNPs with longevity remains uncertain and varies with ethnicity. The aim of this study was to investigate whether the functional variable number of tandem repeat (VNTR) MNS16A of TERT is associated with longevity.

METHODS

MNS16A genotypes have been determined for 1072 unrelated healthy individuals from Central Italy (18-106 years old) divided into three gender-specific age classes defined according to demographic information and accounting for the different survivals between sexes: for men (women), the first class consists of individuals <66 years old (<73 years old), the second class of individuals 66-88 years old (73-91 years old), and the third class of individuals >88 years old (>91 years old). TL was assessed using genomic DNA from whole blood of 72 selected individuals by a multiplex real-time PCR assay.

RESULTS

MNS16A appears associated to longevity, showing significant associations in Comparison 2 (Age Class 3 vs. Age Class 2) under both additive (odds ratio [O.R.] 0.749; p=0.019) and dominant (O.R. 0.579; p=0.011) models. The MNS16A*L allele is significantly underrepresented in Age Class 3 (O.R. 0.759; p=0.020) compared to Age Class 2. A significant telomere attrition is reported along the three age classes (p=0.0001), that remains significant only in L*/L* genotype carriers (p=0.002) when the analysis was conducted according to MNS16A genotype.

CONCLUSIONS

The TERT MNS16A*L allele appears negatively associated with longevity. The concomitant significant telomere cross sectional attrition rate observed for L*/L* genotype suggests that this polymorphism could influence human longevity by affecting TL.

The TERT MNS16A polymorphism contributes to cancer susceptibility: meta-analysis of the current studies

The MNS16A polymorphism in the telomerase reverse transcriptase (TERT) gene has been implicated in cancer risk in multiple populations and various types of cancers; however, the results of previous studies exploring this association were inconclusive. To more precisely evaluate the relationship between the TERT MNS16A polymorphism and cancer risk, we performed a meta-analysis based on 8 studies described in 7 articles comprising 7864 controls and 4355 cases. The summary odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were estimated to assess the strength of the association in a fixed-effects model or a random-effects model where appropriate. Heterogeneity among articles and their publication bias were also tested. Overall, the pooled results indicated that the MNS16A polymorphism was significantly associated with increased cancer risk in the homozygote comparison model (SS vs. LL: OR=1.280, 95% CI 1.060-1.547) and the recessive model (SS vs. LL+SL: OR=1.201, 95% CI 1.004-1.436). In the stratified analyses, a statistically significant association was observed among Caucasians and in population-based studies. We also performed the analyses by cancer type, and a significantly increased risk of glioma was found in four genetic models. Our results suggest that the TERT MNS16A polymorphism most likely contributes to an increased risk of cancer. Moreover, the same relationship was found when the studies were stratified by cancer type, ethnicity and source of controls.

MNS16A tandem repeat minisatellite of human telomerase gene and prostate cancer susceptibility

Telomere dysfunction is an early event in the development of prostate cancer and telomerase (TERT) activity is detectable in the majority of prostate cancers. Genetic variation in TERT and its regulatory elements may influence prostate carcinogenesis. MNS16A, a functional polymorphic tandem repeat minisatellite of TERT, has been studied in several malignancies. We determined MNS16A genotypes in an Austrian case-control study for the first time in the context of prostate cancer, comprising 1165 prostate cancer cases and 674 benign prostate hyperplasia controls with PCR. In addition to the five reported variable number of tandem repeats (VNTRs), we identified VNTR-212, a rare variant, for the first time in a European population. Multiple logistic regression analysis revealed no differences in genotype distribution between cases and controls. However, in stratified analysis, MNS16A VNTR-274 (OR = 0.25, 95% CI = 0.06-0.79, P = 0.016) and genotype 274/302 (OR = 0.13, 95% CI = 0.01-0.58, P = 0.005) were associated with a significantly decreased risk of prostate cancer in the age group >70 years. Our finding of a MNS16A genotype conferring a protective effect against prostate cancer in older men suggests a potential role of this polymorphism in prostate cancer susceptibility but demands to be validated in further studies.

HTERT MNS16A polymorphism in breast cancer: a case-control study

This case-control study aims to investigate the role of HTERT MNS16A polymorphism as a potential risk factors and/or a prognostic marker for breast cancer. 113 consecutive incident cases of histologically confirmed ductal breast cancer and 124 healthy controls were recruited. HTERT MNS16A polymorphism was genotyped (L: long allele, S: short allele); multivariate logistic regression was performed. No significant association was noted either at the overall analysis (OR = 1.57, 95 % CI 0.84-2.93 for heterozygous LS carriers; OR = 1.02, 95 % CI 0.54-1.95 for homozygous SS carriers) or at the subanalyses in premenopausal and postmenopausal women. With respect to survival analysis, HTERT MNS16A polymorphism was not associated with either disease-free survival or overall survival. HTERT MNS16A polymorphism does not seem to be a risk factor for breast cancer in the Caucasian Greek population. Further, larger studies from other countries and subjects seem to be needed as this novel polymorphism is being examined in depth.

Pathway analyses identify TGFBR2 as potential breast cancer susceptibility gene: results from a consortium study among Asians

BACKGROUND

The TGF-β signaling pathway plays a significant role in the carcinogenic process of breast cancer.

METHODS

We systematically evaluated associations of common variants in TGF-β signaling pathway genes with breast cancer risk using a multistage, case-control study among Asian women.

RESULTS

In the first stage, 341 single-nucleotide polymorphisms with minor allele frequencies ≥ 0.05 across 11 genes were evaluated among 2,926 cases and 2,380 controls recruited as a part of the Shanghai Breast Cancer Genetics Study (SBCGS). In the second stage, 20 SNPs with promising associations were evaluated among an additional 1,890 cases and 2,000 controls from the SBCGS. One variant, TGFBR2 rs1078985, had highly consistent and significant associations with breast cancer risk among participants in both study stages, as well as promising results from in silico analysis. Additional genotyping was carried out among 2,475 cases and 2,343 controls from the SBCGS, as well as among 5,077 cases and 5,384 controls from six studies in the Asian Breast Cancer Consortium (stage III). Pooled analysis of all data indicated that minor allele homozygotes (GG) of TGFBR2 rs1078985 had a 24% reduced risk of breast cancer compared with major allele carriers (AG or AA; OR, 0.76; 95% CI, 0.65-0.89; P = 8.42 × 10(-4)).

CONCLUSION

These findings support a role for common genetic variation in TGF-β signaling pathway genes, specifically in TGFBR2, in breast cancer susceptibility.

IMPACT

These findings may provide new insights into the etiology of breast cancer as well as future potential therapeutic targets.

A functional tandem-repeats polymorphism in the downstream of TERT is associated with the risk of nasopharyngeal carcinoma in Chinese population

BACKGROUND

Increases in human telomerase reverse transcriptase (TERT) expression and telomerase activity are frequently seen in nasopharyngeal carcinoma (NPC). Recently, a variable tandem-repeats polymorphism, MNS16A, located in the downstream region of the TERT gene, was identified and reported to have an effect on TERT expression and telomerase activity. We examined whether the functional MNS16A was related to the risk of occurrence or progression of NPC in the Chinese population.

METHODS

We genotyped the MNS16A polymorphism in a case-control study of 855 patients with NPC and 1036 cancer-free controls using PCR, and determined genotype by classifying the DNA band of 243 or 272 base pairs (bp) as the short (S) allele and 302 or 333 bp as the long (L) allele. The genetic associations with the risk of NPC were analyzed by logistic regression.

RESULTS

The MNS16A genotype was not associated with the progression of NPC. However, individuals carrying the S alleles (SL + SS genotype) had a significantly reduced risk of NPC occurrence compared with those carrying the LL genotype (odds ratio (OR) = 0. 71, 95% confidence interval (CI) = 0. 52 to 0. 96, P = 0. 025). Using a immunohistochemical assay on the NPC tissues, the SL genotype carriers were found to have lower TERT expression than the LL genotype carriers (P = 0. 035).

CONCLUSIONS

Our study indicates that the TERT MNS16A polymorphism may contribute to the risk of NPC onset in Chinese population.

Genome-wide association study identifies breast cancer risk variant at 10q21.2: results from the Asia Breast Cancer Consortium

Although approximately 20 common genetic susceptibility loci have been identified for breast cancer risk through genome-wide association studies (GWASs), genetic risk variants reported to date explain only a small fraction of heritability for this common cancer. We conducted a four-stage GWAS including 17 153 cases and 16 943 controls among East-Asian women to search for new genetic risk factors for breast cancer. After analyzing 684 457 SNPs in 2062 cases and 2066 controls (Stage I), we selected for replication among 5969 Chinese women (4146 cases and 1823 controls) the top 49 SNPs that had neither been reported previously nor were in strong linkage disequilibrium with reported SNPs (Stage II). Three SNPs were further evaluated in up to 13 152 Chinese and Japanese women (6436 cases and 6716 controls) (Stage III). Finally, two SNPs were evaluated in 10 847 Korean women (4509 cases and 6338 controls) (Stage IV). SNP rs10822013 on chromosome 10q21.2, located in the zinc finger protein 365 (ZNF365) gene, showed a consistent association with breast cancer risk in all four stages with a combined per-risk allele odds ratio of 1.10 (95% CI: 1.07-1.14) (P-value for trend = 5.87 × 10(-9)). In vitro electrophoretic mobility shift assays demonstrated the potential functional significance of rs10822013. Our results strongly implicate rs10822013 at 10q21.2 as a genetic risk variant for breast cancer among East-Asian women.

MNS16A tandem repeats minisatellite of human telomerase gene: a risk factor for colorectal cancer

Telomerase reactivation and expression of human telomerase gene [human telomerase reverse transcriptase (hTERT)] are hallmarks of unlimited proliferation potential of cancer cells. A polymorphic tandem repeats minisatellite of hTERT gene, termed MNS16A was reported to influence hTERT expression. To assess the role of MNS16A as potential biomarker for colorectal cancer (CRC), we investigated for the first time the association of MNS16A genotypes with risk of colorectal polyps and CRC. In the ongoing colorectal cancer study of Austria (CORSA), 3842 Caucasian participants were recruited within a large screening project in the province Burgenland including 90 CRC cases, 308 high-risk polyps, 1022 low-risk polyps and 1822 polyp free controls verified by colonoscopy. MNS16A genotypes were determined by polymerase chain reaction from genomic DNA. Associations of MNS16A genotypes with CRC risk were estimated by logistic regression analysis computing odds ratios (ORs) and 95% confidence intervals (CIs). We identified five different variable number of tandem repeats (VNTRs) of MNS16A including VNTR-364, a newly discovered rare variant. VNTR-274 allele was associated with a 2.7-fold significantly increased risk of CRC compared with the VNTR-302 wild-type (OR = 2.69; 95% CI = 1.11-6.50; P = 0.028). In our CORSA study, the medium length VNTR-274 was identified as risk factor for CRC. Although, this population-based study herewith reports the largest cohort size concerning MNS16A thus far, further large-scale studies in diverse populations are warranted to confirm hTERT MNS16A genotype as potential biomarker for assessment of CRC risk.

Replication and functional genomic analyses of the breast cancer susceptibility locus at 6q25.1 generalize its importance in women of chinese, Japanese, and European ancestry

We evaluated the generalizability of a single nucleotide polymorphism (SNP), rs2046210 (A/G allele), associated with breast cancer risk that was initially identified at 6q25.1 in a genome-wide association study conducted among Chinese women. In a pooled analysis of more than 31,000 women of East-Asian, European, and African ancestry, we found a positive association for rs2046210 and breast cancer risk in Chinese women [ORs (95% CI) = 1.30 (1.22-1.38) and 1.64 (1.50-1.80) for the AG and AA genotypes, respectively, P for trend = 1.54 × 10⁻³⁰], Japanese women [ORs (95% CI) = 1.31 (1.13-1.52) and 1.37 (1.06-1.76), P for trend = 2.51 × 10⁻⁴], and European-ancestry American women [ORs (95% CI) = 1.07 (0.99-1.16) and 1.18 (1.04-1.34), P for trend = 0.0069]. No association with this SNP, however, was observed in African American women [ORs (95% CI) = 0.81 (0.63-1.06) and 0.85 (0.65-1.11) for the AG and AA genotypes, respectively, P for trend = 0.4027]. In vitro functional genomic studies identified a putative functional variant, rs6913578. This SNP is 1,440 bp downstream of rs2046210 and is in high linkage disequilibrium with rs2046210 in Chinese (r(2) = 0.91) and European-ancestry (r² = 0.83) populations, but not in Africans (r² = 0.57). SNP rs6913578 was found to be associated with breast cancer risk in Chinese and European-ancestry American women. After adjusting for rs2046210, the association of rs6913578 with breast cancer risk in African Americans approached borderline significance. Results from this large consortium study confirmed the association of rs2046210 with breast cancer risk among women of Chinese, Japanese, and European ancestry. This association may be explained in part by a putatively functional variant (rs6913578) identified in the region.

Dual roles of a variable number of tandem repeat polymorphism in the TERT gene in lung cancer

This study was conducted to determine the impact of a functional tandem repeat minisatellite (MNS16A) polymorphism in the telomerase reverse transcriptase (TERT) gene on the risk of lung cancer, as well as on survival of patients with non-small-cell lung cancer (NSCLC). The effect of the MNS16A variable number of tandem repeat (VNTR) polymorphism on the risk of lung cancer was evaluated in a case-control study that consisted of 937 lung cancer patients and 943 healthy controls. The effect of the polymorphism on survival outcome was evaluated in 703 patients with surgically resected NSCLC. Compared with the VNTR-302 allele, the VNTR-243 allele was associated with a significantly increased risk of lung cancer (adjusted odds ratio, 1.55; 95% confidence interval [CI], 1.07-2.25; P = 0.02). In addition, the genotypes carrying at least one VNTR-243 allele were associated with a significantly increased risk of lung cancer compared with the genotypes with no VNTR-243 allele (adjusted odds ratio, 1.61; 95% CI, 1.09-2.38; P = 0.02). In contrast to the effect of the polymorphism on the risk of lung cancer, the genotypes carrying at least one VNTR-243 allele were associated with a significantly better overall survival in patients with surgically resected NSCLC (adjusted hazard ratio, 0.51; 95% CI, 0.28-0.93; P = 0.03). These findings suggest that the MNS16A VNTR polymorphism in the TERT gene has dual, conflicting roles in lung carcinogenesis. This polymorphism may increase the risk of lung cancer development, and may improve survival in lung cancer patients.

Short rare hTERT-VNTR2-2nd alleles are associated with prostate cancer susceptibility and influence gene expression

Background

The hTERT (human telomerase reverse transcriptase) gene contains five variable number tandem repeats (VNTR) and previous studies have described polymorphisms for hTERT-VNTR2-2^nd. We investigated how allelic variation in hTERT-VNTR2-2^nd may affect susceptibility to prostate cancer.

Methods

A case-control study was performed using DNA from 421 cancer-free male controls and 329 patients with prostate cancer. In addition, to determine whether the VNTR polymorphisms have a functional consequence, we examined the transcriptional levels of a reporter gene linked to these VNTRs and driven by the hTERT promoter in cell lines.

Results

Three new rare alleles were detected from this study, two of which were identified only in cancer subjects. A statistically significant association between rare hTERT-VNTR2-2^nd alleles and risk of prostate cancer was observed [OR, 5.17; 95% confidence interval (CI), 1.09-24.43; P = 0.021]. Furthermore, the results indicated that these VNTRs inserted in the enhancer region could influence the expression of hTERT in prostate cancer cell lines.

Conclusions

This is the first study to report that rare hTERT VNTRs are associated with prostate cancer predisposition and that the VNTRs can induce enhanced levels of hTERT promoter activity in prostate cancer cell lines. Thus, the hTERT-VNTR2-2^nd locus may function as a modifier of prostate cancer risk by affecting gene expression.

Identification of a functional genetic variant at 16q12.1 for breast cancer risk: results from the Asia Breast Cancer Consortium

Genetic factors play an important role in the etiology of breast cancer. We carried out a multi-stage genome-wide association (GWA) study in over 28,000 cases and controls recruited from 12 studies conducted in Asian and European American women to identify genetic susceptibility loci for breast cancer. After analyzing 684,457 SNPs in 2,073 cases and 2,084 controls in Chinese women, we evaluated 53 SNPs for fast-track replication in an independent set of 4,425 cases and 1,915 controls of Chinese origin. Four replicated SNPs were further investigated in an independent set of 6,173 cases and 6,340 controls from seven other studies conducted in Asian women. SNP rs4784227 was consistently associated with breast cancer risk across all studies with adjusted odds ratios (95% confidence intervals) of 1.25 (1.20−1.31) per allele (P = 3.2×10⁻²⁵) in the pooled analysis of samples from all Asian samples. This SNP was also associated with breast cancer risk among European Americans (per allele OR  = 1.19, 95% CI  = 1.09−1.31, P = 1.3×10⁻⁴, 2,797 cases and 2,662 controls). SNP rs4784227 is located at 16q12.1, a region identified previously for breast cancer risk among Europeans. The association of this SNP with breast cancer risk remained highly statistically significant in Asians after adjusting for previously-reported SNPs in this region. In vitro experiments using both luciferase reporter and electrophoretic mobility shift assays demonstrated functional significance of this SNP. These results provide strong evidence implicating rs4784227 as a functional causal variant for breast cancer in the locus 16q12.1 and demonstrate the utility of conducting genetic association studies in populations with different genetic architectures.

Breast cancer is one of the most common malignancies among women worldwide. Genetic factors play an important role in the etiology of breast cancer. To identify genetic susceptibility loci for breast cancer, we performed a genome-wide association study in 15,468 breast cancer cases and 13,001 controls. A single nucleotide polymorphism (SNP) rs4784227 located on chromosome 16q12.1, a previously-reported region for breast cancer risk, was found to be associated with breast cancer risk. The association of this SNP with breast cancer risk remained highly significant in Asians after adjusting all previously-reported SNPs in this region. In vitro biochemical experiments using both luciferase reporter and electrophoretic mobility shift assays confirmed the functional importance of this SNP. Our results demonstrate the importance of conducting genetic association studies in populations with different genetic backgrounds to identify functional variants.

Multiple genetic variants in telomere pathway genes and breast cancer risk

PURPOSE

To explore the etiologic role of genetic variants in telomere pathway genes and breast cancer risk.

METHODS

A population-based case-control study, the Long Island Breast Cancer Study Project, was conducted, and 1,067 cases and 1,110 controls were included in the present study. Fifty-two genetic variants of nine telomere-related genes were genotyped.

RESULTS

Seven single nucleotide polymorphisms (SNP) showed significant case-control differences at the level of P < 0.05. The top three statistically significant SNPs under a dominant model were TERT-07 (rs2736109), TERT-54 (rs3816659), and POT1-03 (rs33964002). The odds ratios (OR) were 1.56 [95% confidence interval (95% CI), 1.22-1.99] for the TERT-07 G-allele, 1.27 (95% CI, 1.05-1.52) for the TERT-54 T-allele, and 0.79 (95% CI, 0.67-0.95) for the POT1-03 A-allele. TERT-67 (rs2853669) was statistically significant under a recessive model; the OR of the CC genotype was 0.69 (95% CI, 0.69-0.93) compared with the T-allele. However, none of the SNPs retained significance after Bonferroni adjustment for multiple testing at the level of P < 0.001 (0.05/52) except for TERT-07. When restricted to Caucasians (94% of the study subjects), a stronger association for the TERT-07 G-allele was observed with an OR of 1.60 (95% CI, 1.24-2.05; P = 0.0002). No effect modifications were found for variant alleles and menopausal status, telomere length, cigarette smoking, body mass index status, and family history of breast cancer risk.

CONCLUSIONS

Four SNPs in the TERT and POT1 genes were significantly related with overall breast cancer risk. This initial analysis provides valuable clues for further exploration of the biological role of telomere pathway genes in breast cancer.