TERT rs2736100 genotypes are associated with differential risk of myeloproliferative neoplasms in Swedish and Chinese male patient populations

Genetic association study of TERT gene variants with chronic kidney disease susceptibility in the Chinese population

The incidence and mortality of chronic kidney disease (CKD) are increasing globally. Studies have demonstrated the significance of genetic risk factors in the progression of CKD. Telomerase reverse transcriptase (TERT) may be implicated in the development of CKD. This study aimed to investigate the correlation between TERT gene variants and susceptibility to CKD in the Chinese population. A total of 507 patients with CKD and 510 healthy controls were recruited for this case-control study. Four candidate loci were identified using the MassARRAY platform. Logistic regression analysis was employed to assess the association between TERT gene variants and the risk of CKD. The false positive reporting probability (FPRP) method was utilized to evaluate the validity of statistically significant associations. The multifactorial dimensionality reduction (MDR) method was used to evaluate the interaction between SNPs and the risk of CKD. Furthermore, discrepancies in the clinical features of subjects with diverse genotypes were evaluated using one-way analysis of variance (ANOVA). Our findings revealed a correlation between rs2735940 and rs4635969 and an increased risk of CKD. Stratification analysis indicated that rs4635969 was related to an increased risk of CKD in different subgroups (age ≤ 50 years and male). MDR analysis indicated that the two-site model (rs2735940 and rs4635969) was the best prediction model. Furthermore, the rs2735940 GG genotype was found to be linked to an increased level of microalbuminuria (MAU) in patients with CKD. Our study is the first to reveal a connection between TERT gene variants and susceptibility to CKD, providing new insights into the field of nephrology.

Germline genetic variants that predispose to myeloproliferative neoplasms and hereditary myeloproliferative phenotypes

Epidemiological evidence of familial predispositions to myeloid malignancies and myeloproliferative neoplasms (MPN) has long been recognised, but recent studies have added to knowledge of specific germline variants in multiple genes that contribute to the familial risk. These variants may be common risk alleles in the general population but have low penetrance and cause sporadic MPN, such as the JAK2 46/1 haplotype, the variant most strongly associated with MPN. Association studies are increasingly identifying other MPN susceptibility genes such as TERT, MECOM, and SH2B3, while some common variants in DDX41 and RUNX1 appear to lead to a spectrum of myeloid malignancies. RBBP6 and ATM variants have been identified in familial MPN clusters and very rare germline variants such as chromosome 14q duplication cause hereditary MPN with high penetrance. Rarely, there are hereditary non-malignant diseases with an MPN-like phenotype. Knowledge of those genes and germline genetic changes which lead to MPN or diseases that mimic MPN helps to improve accuracy of diagnosis, aids with counselling regarding familial risk, and may contribute to clinical decision-making. Large scale population exome and genome sequencing studies will improve our knowledge of both common and rare germline genetic contributions to MPN.

Telomere length and hTERT genetic variants as potential prognostic markers in multiple myeloma

Telomere dysfunction is a notable event observed in many cancers contributing to their genomic instability. A major factor controlling telomere stability is the human telomerase reverse transcriptase catalytic subunit (hTERT). Telomere shortening has been observed in multiple myeloma (MM), a plasma cell malignancy with a complex and heterogeneous genetic background. In the present study, we aimed to analyse telomere length and hTERT genetic variants as potential markers of risk and survival in 251 MM patients. We found that telomere length was significantly shorter in MM patients than in healthy individuals, and patients with more advanced disease (stage III according to the International Staging System) had shorter telomeres than patients with less advanced disease. MM patients with hTERT allele rs2736100 T were characterized with significantly shorter progression-free survival (PFS). Moreover, allele rs2736100 T was also found to be less common in patients with disease progression in response to treatment. hTERT rs2853690 T was associated with higher haemoglobin blood levels and lower C-reactive protein. In conclusion, our results suggest that telomere length and hTERT genetic variability may affect MM development and can be potential prognostic markers in this disease.

Do Polymorphisms of the TERT, GSTM1, and GSTT1 Genes Increase Laryngeal Cancer Susceptibility in Smokers of Romanian Descent?

Background and Objectives: The aim of this study was to investigate the association between smoking status and single-nucleotide polymorphism in candidate genes that had a known association with smoking-related tumors in previous studies and to explore their link to laryngeal cancer risk in a population of northern Romanian descent. The genes selected have key functions in xenobiotic metabolism (GSTs: the glutathione S-transferases family: GSTM1 and GSTT1) and chromosomal management (TERT). Materials and Methods: The genotype frequencies of TERT_Rs2736100 and the GST subfamilies (GSTM1 and GSTT1) were determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The relationship between the polymorphisms and the risk of laryngeal cancer was analyzed in a retrospective case–control study of 92 laryngeal cancer cases and 101 controls, all of whom were smokers. Results: Subjects presenting the GSTT1-null variant had a two-fold increase in risk (OR = 2.05, 95% CI = 1.07–3.95, p = 0.02). While no individual risk was observed for the TERT_Rs2736100 polymorphism, stratification based on gender revealed a nine-fold increase in risk for carriers of the “C” allele in the heterozygote variant who were male (OR = 9, 65% CI = 3.51–26.51, p = 0.0000). Conclusions: The results showed that the GSTT1-null genotype and the mutant heterozygote variant of TERT_Rs2736100 genes may play a significant role in laryngeal cancer susceptibility in subjects of northern Romanian descent. There may be no association between the susceptibility to laryngeal carcinoma and the GSTM1 polymorphism. The results could not confirm the carcinogenic influence smoking has on laryngeal cancer development for the studied polymorphisms.

Assessment of Telomerase Reverse Transcriptase Single Nucleotide Polymorphism in Sleep Bruxism

Introduction: Sleep bruxism (SB) is a widespread masticatory muscle activity during sleep and affects approximately 13.2% of the general population. Telomerase reverse transcriptase (TERT) plays a role in preventing the shortening of the telomere. This prospective, observational study aimed to investigate the relationship between single nucleotide polymorphism (SNP) of TERT and the severity of SB and to identify the independent risk factors for SB. Methods: A total of 112 patients were diagnosed by performing one-night polysomnography based on the guidelines of the American Academy of Sleep Medicine. TERT SNP was detected by real-time quantitative polymerase chain reaction (qPCR). Results: Statistical analysis showed the lack of relationship between the rs2853669 polymorphism of TERT and severity of SB (p > 0.05). However, the study showed that patients with allele T in the 2736100 polymorphism of TERT had a lower score on the phasic bruxism episode index (BEI). Based on the receiver operating characteristic (ROC) curve, the value of phasic BEI was 0.8 for the differential prediction for the presence of allele T in the locus. The sensitivity and specificity were 0.328 and 0.893, respectively. The regression analysis showed that lack of TERT rs2736100 T allele, male gender, and arterial hypertension are the risk factors for the higher value of phasic BEI. Conclusion: The SNP of the TERT gene affects phasic SB intensity. The absence of TERT rs2736100 T allele, male sex, and arterial hypertension are independent risk factors for phasic SB.

TERT rs2853669 as a predictor for overall survival in patients with acute myeloid leukaemia

INTRODUCTION

the aim of the study was to investigate the contribution of TERT rs2736100 and rs2853669 gene polymorphisms in defining the genetic predisposition to acute myeloid leukaemia (AML), their association with different prognostic markers, and their impact on survival, outcome, and the prognosis of affected patients. Also, we investigated the association of TERT SNPs in AML in the presence or absence of DNMT3A (R882), NPM1, and FLT3 mutations.

MATERIAL AND METHODS

A total of 509 participants were enrolled in our study, consisting of 146 AML patients and 363 healthy participants, with no history of malignancy. TERT rs2736100 and rs2853669 polymorphisms were genotyped by using TaqMan SNP genotyping assay FLT3 (ITD, D835), DNMT3A (R882), and NPM1 c.863_864insTCTG (type A) mutations were analised in each AML case.

RESULTS

TERT rs2736100 and rs2853669 were not associated with AML risk in the codominant, dominant, recessive, or allelic models. Multivariate Cox regression showed that TERT rs2853669 was a significant predictor for overall survival in AML patients. After adjusting for age, gender, cytogenetic risk group, ECOG status, FLT3, DNMT3A, NPM1 mutation, AML subtype, and treatment, the estimated adjusted hazard ratio (HR adjusted = 1.54, 95% CI: 1.01-2.35) showed that the TERT rs2853669 variant genotype had a negative influence on survival time.

CONCLUSIONS

TERT rs2853669 and rs2736100 polymorphisms were not risk factors for developing AML in the Romanian population, but the TERT rs2853669 variant genotype had a negative effect on AML patients' overall survival in the presence of other known prognostic factors.

Telomeres and Cancer

Telomeres cap the ends of eukaryotic chromosomes and are indispensable chromatin structures for genome protection and replication. Telomere length maintenance has been attributed to several functional modulators, including telomerase, the shelterin complex, and the CST complex, synergizing with DNA replication, repair, and the RNA metabolism pathway components. As dysfunctional telomere maintenance and telomerase activation are associated with several human diseases, including cancer, the molecular mechanisms behind telomere length regulation and protection need particular emphasis. Cancer cells exhibit telomerase activation, enabling replicative immortality. Telomerase reverse transcriptase (TERT) activation is involved in cancer development through diverse activities other than mediating telomere elongation. This review describes the telomere functions, the role of functional modulators, the implications in cancer development, and the future therapeutic opportunities.

TERT genetic variability and telomere length as factors affecting survival and risk in acute myeloid leukaemia

Acute myeloid leukaemia (AML) is a neoplasm of immature myeloid cells characterized by various cytogenetic alterations. The present study showed that in addition to the FLT3-ITD and NPM1 mutation status, telomere length (TL) and telomerase reverse transcriptase (TERT) gene polymorphisms may affect risk and overall survival (OS) in AML. TL was longer in healthy controls than in AML patients and positively correlated with age in the patients, but not in healthy subjects. TL was found to be independently affected by the presence of the FLT3-ITD mutation. As for the TERT gene polymorphism, AML patients with the TERT rs2853669 CC genotype were characterized by significantly shorter OS than patients carrying the T allele. Another observation in our study is the difference in TL and OS in patients belonging to various risk stratification groups related to the FLT3-ITD and NPM1 mutation status. Patients with adverse risk classification (mutation in FLT3-ITD and lack of mutation in NPM1) presented with the shortest telomeres and significantly worse OS. In conclusion, OS of AML patients appears to be affected by TERT gene variability and TL in addition to other well-established factors such as age, WBC count, or FLT3-ITD and NPM1 mutation status.

TERT Gene rs2736100 and rs2736098 Polymorphisms are Associated with Increased Cancer Risk: A Meta-Analysis

Abnormal telomerase activity plays a key role in the development of carcinogenesis. The variants rs2736100 and rs2736098 of the telomerase reverse transcriptase (TERT) gene, which encodes the telomerase catalytic subunit, are associated with the risk of different types of cancers. However, the results remain controversy. We conducted a meta-analysis to more precisely assess this association. We comprehensively searched the PubMed and Web of Science databases up to June 1, 2020, and retrieved a total of 103 studies in 82 articles, including 89,320 cases and 121,654 controls. Among these studies, 69 published studies including 75,274 cases and 10,3248 controls were focused on rs2736100, and 34 published studies including 14,046 cases and 18,362 controls were focused on rs2736098. The results showed a strong association between variant rs2736100 and cancer risk in all populations. (G vs. T: OR 1.18, 95% CI 1.12-1.24; TG+GG vs. TT: OR 1.23, 95% CI 1.15-1.31; GG vs. TG+TT: OR 1.25, 95% CI 1.16-1.36); the variant rs2736098 was associated with cancer risk in all populations as well (A vs. G: OR 1.13, 95% CI 1.05-1.22; GA+AA vs. GG: OR 1.15, 95% CI 1.04-1.27; AA vs. GA+GG: OR 1.22, 95% CI 1.10-1.38). Stratified analysis based on the cancer type indicated that rs2736100 was associated with an increased risk of thyroid cancer, bladder cancer, lung cancer, glioma, and myeloproliferative neoplasms. rs2736098 only increased the risk of bladder cancer and lung cancer. Moreover, the TERT variants rs2736100 and rs2736098 were associated with a decreased risk of breast cancer and colorectal cancer. The variants rs2736098 and rs2736100 located in 5p15.33 around TERT were associated with increased cancer risk in all populations. These two variants had bidirectional effects in different tumors.

Telomere-related Markers for Cancer

Telomeres are structurally nucleoprotein complexes at termini of linear chromosomes and essential to chromosome stability/integrity. In normal human cells, telomere length erodes progressively with each round of cell divisions, which serves as an important barrier to uncontrolled proliferation and malignant transformation. In sharp contrast, telomere maintenance is a key feature of human malignant cells and required for their infinite proliferation and maintenance of other cancer hallmarks as well. Thus, a telomere-based anti-cancer strategy has long been suggested. However, clinically efficient and specific drugs targeting cancer telomere-maintenance have still been in their infancy thus far. To achieve this goal, it is highly necessary to elucidate how exactly cancer cells maintain functional telomeres. In the last two decades, numerous studies have provided profound mechanistic insights, and the identified mechanisms include the aberrant activation of telomerase or the alternative lengthening of telomere pathway responsible for telomere elongation, dysregulation and mutation of telomere-associated factors, and other telomere homeostasis-related signaling nodes. In the present review, these various strategies employed by malignant cells to regulate their telomere length, structure and function have been summarized, and potential implications of these findings in the rational development of telomere-based cancer therapy and other clinical applications for precision oncology have been discussed.

Telomerase reverse transcriptase promoter mutations in thyroid carcinomas: implications in precision oncology-a narrative review

Telomerase is a ribonucleoprotein enzyme with telomerase reverse transcriptase (TERT) as a catalytic component. In normal human follicular thyroid cells or thyrocytes, telomerase is silent due to the TERT gene being tightly repressed. However, during the formation of thyroid carcinoma (TC), telomerase becomes activated via TERT induction. The TERT promoter’s gain-of-function mutation has recently been identified in TCs and many other malignancies. The mutation creates a de novo ETS-binding motif through which TERT transcription is de-repressed and telomerase is activated; through this, the mutant TERT promoter promotes the development of TC, contributes to disease aggressiveness and treatment resistance, and thereby leads to poor patient outcomes. From a clinical point of view, the strong association between the TERT promoter mutation and disease malignancy and aggressiveness holds great promise for its value in TC diagnostics, risk stratification, prognostication, treatment decision, and follow-up design. In the present review article, we summarize the recent findings of studies of TERT promoter mutations in TC and underscore the implications of TERT hyperactivity driven by genetic events in the pathogenesis and management of TC. Finally, the targeting of TERT promoter mutations and the disruption of telomere maintenance are considered as potential therapeutic strategies against TC.

Genetic polymorphisms and expression of NLRP3 inflammasome-related genes are associated with Philadelphia chromosome-negative myeloproliferative neoplasms

Inflammation plays a crucial role in the initiation, progression and prognosis of Philadelphia chromosome-negative myeloproliferative neoplasms (MPN), which could be clinically subdivided into polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Nucleotide binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasomes affect inflammatory diseases and carcinomas by excessive production of cytokines. To investigate a possible association of NLRP3 inflammasome signaling with MPN, we investigated the expression of selected inflammasome-related genes from bone marrow cells of 67 MPN patients as well as gene polymorphisms in NLRP3 (rs35829419), NF-κB1 (rs28362491), CARD8 (rs2043211), IL-1β (rs16944), and IL-18 (rs1946518). It showed that inflammasome-related genes (NLRP3, NF-κB1, CARD8, IL-1β, and IL-18) were highly expressed in BM cells from MPN patients and the increased expression was associated with JAK2^V617F mutation, white blood cell counts and splenomegaly. Analysis of genetic polymorphisms in 269 MPN patients and 291 healthy controls demonstrated that NF-κB1 (rs28362491) was associated with MPN and increased expression of NF-κB1, NLRP3 and IL-1β. This research provided novel biomarkers and potential targets for MPN.

TERT promoter mutations and GABP transcription factors in carcinogenesis: More foes than friends

The transcriptional de-repression of the telomerase reverse transcriptase (TERT) gene and subsequent activation of telomerase is a prerequisite step in malignant transformation and progression. Recently, the gain-of-function mutation of the TERT promoter was identified in many types of human malignancies, and the mutated promoter acquires de novo ETS binding motifs through which the TERT transcription is activated. The ETS family transcription factors GABPA and GABPB1 have been shown to act as master drivers for the mutant TERT promoter activity. Indeed, GABPA or GABPB1 depletion leads to the down-regulation of TERT expression in the mutant TERT promoter-bearing cancer cells, and is thus proposed as targets for cancer therapy. Surprisingly, however, despite its key role in activating the mutant TERT promoter and telomerase, GABPA may itself function as a potent tumor suppressor in several malignancies. In this review, we address the collaboration between GABPA and mutant TERT promoter in cancer development, discuss selection trade-offs among different activities of GABPA in cancer evolution, and underscore the suppressive function of GABPA in cancer progression and implications in precision oncology.

Patients with benign prostatic hyperplasia show shorter leukocyte telomere length but no association with telomerase gene polymorphisms in Han Chinese males

OBJECTIVE

Benign prostatic hyperplasia (BPH) is an age-related disease, occurring in >70% of men of age >60. Because telomeres and telomerase play a key role in aging and age-related diseases, and certain telomerase gene single nucleotide polymorphisms (SNPs) are shown to be associated with the susceptibility to age-related diseases, we wanted to determine the relationship between BPH and leukocyte telomere length (LTL) and telomere length-related single nucleotide polymorphisms (SNPs) of the telomerase holoenzyme genes.

METHODS

Peripheral blood was collected from both BPH patients and age-matched healthy male controls and genomic DNA was extracted. rs2736100 and rs2736098 at the TERT and rs12696304 at the TERC locus were analysed using pre-designed TaqMan SNP genotyping assay kits. LTL was determined using qPCR.

RESULTS

Patients with BPH had significantly shorter LTL (1.231 ± 0.532 vs 0.899 ± 0.322, P < 0.001). The genotyping results show similar frequencies in rs2736100, rs2736098 and rs12696304 between healthy and BPH individuals.

CONCLUSIONS

Shorter telomeres but not telomerase SNPs at the TERT and TERC loci, are associated with BPH. Short telomeres may promote senescence of a fraction of prostatic epithelial cells, while senescent cells in turn facilitate epithelial and stromal cell proliferation by the senescence-associated secretory phenotype mechanism, thereby eventually leading to BPH development.

The telomerase gene polymorphisms, but not telomere length, increase susceptibility to primary glomerulonephritis/end stage renal diseases in females

Background

Primary glomerulonephritis (GN) is the leading cause of chronic kidney disease (CKD) and frequently progresses into end stage renal diseases (ESRDs). Shorter leukocyte telomere length (LTL) has been implicated in the CKD susceptibility and diminished kidney function, however, it is unclear whether the variants in telomerase genes contribute to risk to GN/CKD/ESRD. Here we address this issue by determining their association with the genetic variants of rs12696304 at the telomerase RNA component (TERC) and rs2736100 at the telomerase reverse transcriptase (TERT) loci.

Methods

The study includes 769 patients (243 primary GN-derived CKD and 526 ESRD cases) and sex-/age-matched healthy controls. Genomic DNA was extracted from peripheral blood of both controls and patients. Genotyping of rs12696304 and rs2736100 variants was carried out using PCR-based assays. Leukocyte telomere length (LTL) was determined using quantitative PCR (qPCR).

Results

A significantly higher frequency of TERC rs12696304 G allele was observed in patients and associated with increased disease risk (C vs G: OR = 1.334, 95% CI 1.112–1.586, P = 0.001; CC + GC vs GG: OR = 1.334, 95% CI 1.122–1.586, P = 0.001). Further analyses showed that such significant differences were only present between female controls and patients (C vs G: OR = 1.483, 95% CI 1.140–1.929, P = 0.003; CC + GC vs CC: OR = 1.692, 95% CI 1.202–2.383, P = 0.003), but not males. There were no differences in rs2736100 variants between controls and patients, but female ESRD patients carried significantly higher C allele frequencies than did female controls (A vs C: OR = 1.306, 95% CI 1.005–1.698, P = 0.046; AA vs CC: OR = 1.781, 95% CI 1.033–3.070, P = 0.037). There was no difference in LTL between controls and patients.

Conclusions

Our results reveal that the TERC rs12696304 and TERT rs2736100 polymorphisms, but not LTL per se, contribute to GN/CDK/ESRD risk.

The TERT rs2736100 Polymorphism and Susceptibility to Myeloproliferative Neoplasms: A Systematic Review and Meta-Analysis

Introduction: The classification of myeloproliferative neoplasms (MPN) is currently based on the genotype. Thus, to achieve better diagnostic and prognostic outcomes, it is necessary to further investigate the genetic spectrum underlying the pathogenesis of MPNs. The rs2736100A>C is a functional single nucleotide polymorphism in the telomerase reverse transcriptase (TERT) gene that has been previously reported to be associated with the risk of MPNs. Herein, we performed a meta-analysis to confirm the relationship between the TERT rs2736100A>C polymorphism and MPN susceptibility. Materials and Methods: Studies of case-control design were acquired from online databases with specific inclusion criteria. Odds ratios (ORs) with 95% confidence intervals (95% CI) were estimated to evaluate the association between the TERT rs2736100 polymorphism and MPN susceptibility using different genetic models. Results: Ten case-control studies involving 3488 cases and 57,948 controls were examined. Overall, there was a significant association between the TERT rs2736100 polymorphism and the risk of MPNs (allele model [C vs. A]: OR = 1.57 [95% CI: 1.47-1.69]; homozygous model [CC vs. AA]: OR = 3.00 [95% CI: 2.40-3.76]; heterozygous model [AC vs. AA]: OR = 2.17 [95% CI: 1.77-2.66]; dominant model [CC+AC vs. AA]: OR = 2.43 [95% CI: 2.00-2.95]; and recessive model [CC vs. AC+AA]: OR = 1.73 [95% CI: 1.47-2.04]). Conclusions: In this meta-analysis, we confirm an association between the TERT rs2736100A>C polymorphism and MPN susceptibility under all genetic models evaluated. The TERT rs2736100A>C allele increases the overall risk of MPN. Further studies are warranted to determine the functional role of the TERT rs2736100 polymorphism in MPN.

Shorter Leukocyte Telomere Length coupled with lower expression of Telomerase Genes in patients with Essential Hypertension

Background: The essential hypertension (EH) pathophysiology remains poorly understood. Many studies indicate that reduced leukocyte telomere length (LTL) is involved in the EH pathogenesis, however, the direct analysis of arterial telomere length (ATL) from EH patients and normotensive individuals did not show a difference. To address these discrepant observations between LTL and ATL, we performed comprehensive analyses of LTL, telomerase gene expression and their genetic variants in healthy normotensive controls and EH patients. Methods: Sex-matched 206 EH patients and equal numbers of healthy controls were recruited. LTL, and the expression of two key telomerase components, telomerase reverse transcriptase (TERT) and internal RNA template (TERC) were determined using qPCR. Genetic variants of rs2736100 at the TERT and rs12696304 at the TERC loci were determined using TaqMan genotyping kits. Results: LTL was significantly shorter in EH patients than in their normotensive controls (0.96 ± 0.52 vs 1.19 ± 0.58, P = 0.001). Moreover, TERT and TERC expression in patients' leukocytes were substantially lower compare to that in healthy controls (TERT, 0.98 ± 0.98 vs 1.76 ± 1.75, P = 0.003; TERC, 1.26 ± 1.62 vs 4.69 ± 3.61, P < 0.001). However, there were no differences in the genetic variants of rs2736100 and rs12696304 between patient and control groups. Conclusions: EH patients have significantly shorter LTL, which may result from defective TERT and TERC expression in leukocytes. Collectively, lower telomerase expression contributes to shorter LTL observed in EH patients, and telomerase activators may be considered for EH therapy.

Mechanisms underlying the activation of TERT transcription and telomerase activity in human cancer: old actors and new players

Long-lived species Homo sapiens have evolved robust protection mechanisms against cancer by repressing telomerase and maintaining short telomeres, thereby delaying the onset of the majority of cancer types until post-reproductive age. Indeed, telomerase is silent in most differentiated human cells, predominantly due to the transcriptional repression of its catalytic component telomerase reverse transcriptase (TERT) gene. The lack of telomerase/TERT expression leads to progressive telomere erosion in dividing human cells, whereas critically shortened telomere length induces a permanent growth arrest stage named replicative senescence. TERT/telomerase activation has been experimentally shown to be essential to cellular immortalization and malignant transformation by stabilizing telomere length and erasing the senescence barrier. Consistently, TERT expression/telomerase activity is detectable in up to 90% of human primary cancers. Compelling evidence has also accumulated that TERT contributes to cancer development and progression via multiple activities beyond its canonical telomere-lengthening function. Given these key roles of telomerase and TERT in oncogenesis, great efforts have been made to decipher mechanisms underlying telomerase activation and TERT induction. In the last two decades since the TERT gene and promoter were cloned, the derepression of the TERT gene has been shown to be achieved typically at a transcriptional level through dysregulation of oncogenic factors or signaling, post-transcriptional/translational regulation and genomic amplification. However, advances in high-throughput next-generation sequencing technologies have prompted a revolution in cancer genomics, which leads to the recent discovery that genomic alterations take center stage in activating the TERT gene. In this review article, we summarize critical mechanisms activating TERT transcription, with special emphases on the contribution of TERT promoter mutations and structural alterations at the TERT locus, and briefly discuss the underlying implications of these genomic events-driven TERT hyperactivity in cancer initiation/progression and potential clinical applications as well.

Variability within the human TERT gene, telomere length and predisposition to chronic lymphocytic leukemia

Background: The human telomerase reverse transcriptase (TERT) gene encodes the catalytic subunit of telomerase that is essential for maintenance of telomere length. We aimed to find out whether variability within the TERT gene could be associated with telomere length and development of the disease in non-treated patients with chronic lymphocytic leukemia (CLL). Materials and methods: Telomere length, rs2736100, rs2853690, rs33954691, rs35033501 single-nucleotide polymorphisms, and variable number of tandem repeats (VNTR-MNS16A) were assessed in patients at diagnosis. In addition, blood donors served as controls for the polymorphism studies. Results: The minor rs35033501 A variant was more frequent among CLL patients than in healthy controls (OR=3.488, p=0.039). CLL patients over 60 years of age were characterized with lower disease stage at diagnosis (p=0.001 and p=0.008, for the Rai and Binet criteria, respectively). The MNS16A VNTR-243 short allele was more frequent in patients with a low disease stage (p=0.020 and p=0.028, for the Rai and Binet staging system) and also among older patients having longer telomeres (p=0.046). Patients with Rai 0-I stage were characterized with longer telomeres than those with more advanced disease (p=0.030). This relationship was especially pronounced in patients carrying the rs2736100 C allele, independently of the criteria used, ie, Binet (p=0.048) or Rai (p=0.001). Conclusion: Our results showed that the genetic variation within the TERT gene seems to play a regulatory role in CLL and telomere length.

The TERT locus genotypes of rs2736100-CC/CA and rs2736098-AA predict shorter survival in renal cell carcinoma

OBJECTIVES

The single nucleotide polymorphisms (SNPs) at the TERT rs2736100 and rs2736098 are associated with multicancer susceptibility, however, published findings regarding renal cell carcinoma (RCC) risk are conflicting. In addition, the potential of these SNPs to predict outcomes in RCC remains unclear. The present study is designed to address these questions.

PATIENTS AND METHODS

We recruited 343 patients with RCC and ethnic-/sex-matched healthy controls. TERT rs2736100 and rs2736098 SNPs were analyzed, and their relationships with relapse/survival were evaluated using univariate or multivariate Cox regression.

RESULTS

The genotype distribution did not significantly differ between RCC patients and healthy controls. RCC patients carrying the rs2736100-CC/CA variants had significantly shorter progression-free and overall survival (PFS and OS) than did those AA-carriers (P = 0.009 and 0.032, respectively), while the rs2736098-AA variant was associated with shorter PFS and OS (P = 0.008 and 0.017, respectively). Multivariate analyses showed that rs2736100-CC/CA and rs2736098-AA predicted shorter PFS and OS independently of other established prognostic variables in RCCs. Furthermore, patients carrying both rs2736100-CC/CA and rs2736098-AA had shortest PFS and OS (P = 0.003 and 0.013, respectively) and the hazard ratio of relapse was 7.2 (95% confidence interval: 2.0-26.1).

CONCLUSIONS

There is no significant association between rs2736100/rs2736098 SNPs and RCC risk. rs2736100-CC/CA and rs2736098-AA variants serve as independent predictors of a poor prognosis in RCC. Given that blood or even urinary DNA can be used to genotype these germline variants before treatment, these 2 SNPs may serve as a potential marker for risk stratification.

Association between hTERT Polymorphisms and Female Papillary Thyroid Carcinoma

BACKGROUND

A previous genome-wide association study showed that hTERT rs10069690 and rs2736100 polymorphisms were associated with thyroid cancer risk.

OBJECTIVE

This study further investigated the association between increased risk and clinicopathologic characteristics for Papillary Thyroid Carcinoma (PTC) and hTERT polymorphisms rs10069690 or rs2736100 in a Chinese female population.

METHODS

The hTERT genotypes of 276 PTC patients and 345 healthy subjects were determined with regard to SNPs rs10069690 and rs2736100. The association between these SNPs and the risk of PTC and clinicopathologic characteristics was investigated by logistic regression.

RESULTS

We found a significant difference between PTC and rs10069690 (Odds Ratio (OR) = 1.515; P = 0.005), but not between PTC and rs2736100. When the analysis was limited to females, rs10069690 and rs2736100 were both associated with increased risk for PTC in female individuals (OR = 1.647, P = 0.007; OR = 1.339, P = 0.041, respectively). Further haplotype analysis revealed a stimulative effect of haplotypes TC and CA of TERT rs10069690-rs2736100, which increased risk for PTC in female individuals (OR = 1.579, P = 0.014; OR = 0.726, P = 0.025, respectively). Furthermore, the heterozygote A/C of rs2736100 showed significant difference for age (OR = 0.514, P = 0.047).

CONCLUSION

Our finding suggests that hTERT polymorphisms rs10069690 and rs2736100 are associated with increased risk for PTC in Chinese female population and rs2736100 may be related to age. Consistent with US20170360914 and US20170232075, they are expected to be a potential molecular target for anti-cancer therapy.

The TERT rs2736100 polymorphism increases cancer risk: A meta-analysis

Abnormal telomerase activity is implicated in cancer initiation and development. The rs2736100 T > G polymorphism in the telomerase reverse transcriptase (TERT) gene, which encodes the telomerase catalytic subunit, has been associated with increased cancer risk. We conducted a meta-analysis to more precisely assess this association. After a comprehensive literature search of the PubMed and EMBASE databases up to November 1, 2016, 61 articles with 72 studies comprising 108,248 cases and 161,472 controls were included in our meta-analysis. Studies were conducted on various cancer types. The TERT rs2736100 polymorphism was associated with increased overall cancer risk in five genetic models [homozygous model (GG vs. TT): odds ratio (OR) = 1.39, 95% confidence interval (95% CI) = 1.26-1.54, P < 0.001; heterozygous model (TG vs. TT): OR = 1.16, 95% CI = 1.11-1.23, P < 0.001; dominant model (TG + GG vs. TT): OR = 1.23, 95% CI = 1.15-1.31, P < 0.001; recessive model (GG vs. TG + TT): OR = 1.25, 95% CI = 1.16-1.35, P < 0.001; and allele contrast model (G vs. T): OR = 1.17, 95% CI = 1.12-1.23, P < 0.001]. A stratified analysis based on cancer type associated the polymorphism with elevated risk of thyroid cancer, bladder cancer, lung cancer, glioma, myeloproliferative neoplasms, and acute myeloid leukemia. Our results confirm that the TERT rs2736100 polymorphism confers increased overall cancer risk.

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.

The TERT promoter mutation incidence is modified by germline TERT rs2736098 and rs2736100 polymorphisms in hepatocellular carcinoma

Telomerase activation via induction of the catalytic component telomerase reverse transcriptase (TERT) plays essential roles in malignant transformation. TERT promoter-activating mutations were recently identified as a novel mechanism to activate telomerase in hepatocellular carcinoma (HCC) and many other malignancies. In addition, single nucleotide polymorphisms (SNPs) in the TERT rs2736098 and rs2736100 are significantly associated with cancer susceptibility. It is currently unclear whether different germline TERT variants modify TERT promoter mutations. Here we analyzed the TERT promoter status and genotyped the TERT SNPs at rs2736098 and rs2736100 in patients with HCC. Thirty percent of HCCs harbored TERT promoter mutations and there was a significant difference in rs2736098 and rs2736100 genotypes between wt and mutant TERT promoter-bearing HCC tumors (P = 0.007 and 0.018, respectively). For rs2736100, the cancer risk genotype CC was significantly associated with a reduced incidence of TERT promoter mutations compared to AA + AC variants [Odds ratio (OR): 0.181, 95% Confidence interval (CI): 0.0543-0.601, P = 0.004]. The rs2736098_CT genotype was significantly associated with the TERT promoter mutation-positive tumors compared to the TT genotype (OR: 5.391, 95% CI: 1.234-23.553, P = 0.025). These differences in genotype distribution did not differ between patients with a wt TERT promoter and controls. The presence of TERT promoter mutations was not associated with clinico-pathological variables. Taken together, the germline TERT genetic background may significantly affect the onset of TERT promoter mutations in HCCs, which provides a better understanding of HCC-related TERT promoter mutations and telomerase regulation in cancer.

Association Between the Telomerase rs2736098_TT Genotype and a Lower Risk of Chronic Hepatitis B and Cirrhosis in Chinese Males

OBJECTIVES

Chronic hepatitis B (CHB) is caused by infection of hepatitis B virus (HBV) and liver cirrhosis (LC) is its most common complication. The accumulated evidence indicates a genetic context of HBV infection phenotypes. Here we determine a potential association of CHB/LC with the genetic variant of telomerase reverse transcriptase (TERT), a key player in aging including immune-senescence.

METHODS

The study included 227 Chinese CHB patients and 315 sex/age-matched healthy controls. TERT rs2736098 and rs2736100 genotyping was performed using pre-designed TaqMan SNP genotyping assay kits. Leukocyte telomere length (LTL) was determined using quantitative PCR.

RESULTS

The rs2736098_CT/CC genotypes were significantly associated with risk of CHB compared to the TT one (OR 2.265, 95% CI 1.202-4.269, P=0.015). A similar association was also found in CHB patients with cirrhosis (CT/CC vs TT: OR 2.398, 95% CI 1.168-4.922, P=0.02). Further analyses showed that the rs2736098_TT genotype difference occurred between male controls and patients (P=0.008) and male CT/CC-carriers exhibited highly increased risk of CHB compared to male controls (CT+CC vs TT, OR 3.182, 95% CI 1.350-7.500, P=0.01). There was no difference in the rs2736100 variants between controls and CHB patients. LTL was not different between cases and controls.

CONCLUSIONS

The TERT rs2736098_TT genotype is associated with a lower CHB and LC risk in Chinese males, which may have implications in CHB pathogenesis and prevention.