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

Differential diagnosis of small hepatocellular nodules in cirrhosis: surrogate histological criteria of TERT promoter mutations

AIMS

The differential diagnosis of small hepatocellular nodules in cirrhosis between dysplastic nodules and hepatocellular carcinoma (HCC) remains challenging on biopsy. As TERT promoter (pTERT) mutations may indicate the nodules already engaged in the malignant process, the aim of this study was to identify histological criteria associated with pTERT mutations by detecting these mutations by ddPCR in small formalin-fixed paraffin-embedded (FFPE) hepatocellular nodules arising in cirrhosis.

METHODS AND RESULTS

We built a bicentric cohort data set of 339 hepatocellular nodules < 2 cm from cirrhotic samples, divided into a test cohort of 299 resected samples and a validation cohort of 40 biopsies. Pathological review, based on the evaluation of 14 histological criteria, classified all nodules. pTERT mutations were identified by ddPCR in FFPE samples. Among the 339 nodules, ddPCR revealed pTERT mutations in 105 cases (31%), including 90 and 15 cases in the test and validation cohorts, respectively. On multivariate analysis, three histological criteria were associated with pTERT mutations in the test cohort: increased cell density (P = 0.003), stromal invasion (P = 0.036) and plate-thickening anomalies (P < 0.001). With the combination of at least two of these major criteria, the AUC for predicting pTERT mutations was 0.84 in the test cohort (sensitivity: 86%, specificity: 83%) and 0.81 in the validation cohort (sensitivity: 87%, specificity: 76%).

CONCLUSIONS

We identified three histological criteria as surrogate markers of pTERT mutations that may be used in routine biopsy to more clearly classify small hepatocellular nodules arising in cirrhosis.

Stemness markers in hepatocellular carcinoma of Eastern vs. Western population: Etiology matters?

Hepatocellular carcinoma (HCC) is one of the most common cancers with a high mortality rate. HCC development is associated with its underlying etiologies, mostly caused by infection of chronic hepatitis B virus (HBV) and hepatitis C virus (HCV), alcohol, non-alcoholic fatty liver disease, and exposure to aflatoxins. These variables, together with human genetic susceptibility, contribute to HCC molecular heterogeneity, including at the cellular level. HCC initiation, tumor recurrence, and drug resistance rates have been attributed to the presence of liver cancer stem cells (CSC). This review summarizes available data regarding whether various HCC etiologies may be associated to the appearance of CSC biomarkers. It also described the genetic variations of tumoral tissues obtained from Western and Eastern populations, in particular to the oncogenic effect of HBV in the human genome.

Targeting oncogenic TERT promoter variants by allele-specific epigenome editing

BACKGROUND

Activation of dominant oncogenes by small or structural genomic alterations is a common driver mechanism in many cancers. Silencing of such dominantly activated oncogenic alleles, thus, is a promising strategy to treat cancer. Recently, allele-specific epigenome editing (ASEE) has been described as a means to reduce transcription of genes in an allele-specific manner. In cancer, specificity to an oncogenic allele can be reached by either targeting directly a pathogenic single-nucleotide variant or a polymorphic single-nucleotide variant linked to the oncogenic allele. To investigate the potential of ASEE in cancer, we here explored this approach by targeting variants at the TERT promoter region. The TERT promoter region has been described as one of the most frequently mutated non-coding cancer drivers.

RESULTS

Sequencing of the TERT promoter in cancer cell lines showed 53% (41/77) to contain at least one heterozygous sequence variant allowing allele distinction. We chose the hepatoblastoma cell line Hep-G2 and the lung cancer cell line A-549 for this proof-of-principle study, as they contained two different kinds of variants, namely the activating mutation C228T in the TERT core promoter and the common SNP rs2853669 in the THOR region, respectively. These variants were targeted in an allele-specific manner using sgRNA-guided dCas9-DNMT3A-3L complexes. In both cell lines, we successfully introduced DNA methylation specifically to the on-target allele of the TERT promoter with limited background methylation on the off-target allele or an off-target locus (VEGFA), respectively. We observed a maximum CpG methylation gain of 39% and 76% on the target allele when targeting the activating mutation and the common SNP, respectively. The epigenome editing translated into reduced TERT RNA expression in Hep-G2.

CONCLUSIONS

We applied an ASEE-mediated approach to silence TERT allele specifically. Our results show that the concept of dominant oncogene inactivation by allele-specific epigenome editing can be successfully translated into cancer models. This new strategy may have important advantages in comparison with existing therapeutic approaches, e.g., targeting telomerase, especially with regard to reducing adverse side effects.

Prognostic role and interaction of TERT promoter status, telomere length and MGMT promoter methylation in newly diagnosed IDH wild-type glioblastoma patients

BACKGROUND

The clinical relevance of promoter mutations and single nucleotide polymorphism rs2853669 of telomerase reverse transcriptase (TERT) and telomere length in patients with isocitrate dehydrogenase (IDH) wild-type glioblastoma (GBM) patients remains unclear. Moreover, some studies speculated that TERT promoter status might influence the prognostic role of O6-methylguanine DNA methyltransferase (MGMT) promoter methylation in newly diagnosed GBM. We carried out a large study to investigate their clinical impact and their interaction in newly diagnosed GBM patients.

PATIENTS AND METHODS

We included 273 newly diagnosed IDH wild-type GBM patients who started treatment at Veneto Institute of Oncology IOV - IRCCS (Padua, Italy) from December 2016 to January 2020. TERT promoter mutations (-124 C>T and -146 C>T) and SNP rs2853669 (-245 T>C), relative telomere length (RTL) and MGMT methylation status were retrospectively assessed in this prospective cohort of patients.

RESULTS

Median overall survival (OS) of 273 newly diagnosed IDH wild-type GBM patients was 15 months. TERT promoter was mutated in 80.2% of patients, and most had the rs2853669 single nucleotide polymorphism as T/T genotype (46.2%). Median RTL was 1.57 (interquartile range 1.13-2.32). MGMT promoter was methylated in 53.4% of cases. At multivariable analysis, RTL and TERT promoter mutations were not associated with OS or progression-free survival (PFS). Notably, patients C carrier of rs2853669 (C/C+C/T genotypes) showed a better PFS compared with those with the T/T genotype (hazard ratio 0.69, P = 0.007). In terms of OS and PFS, all interactions between MGMT, TERT and RTL and between TERT and rs2853669 genotype were not statistically significant.

CONCLUSIONS

Our findings suggest the presence of the C variant allele at the rs2853669 of the TERT promoter as an attractive independent prognostic biomarker of disease progression in IDH wild-type GBM patients. RTL and TERT promoter mutational status were not correlated to survival regardless of MGMT methylation status.

Genetic Variants in Telomerase Reverse Transcriptase Contribute to Solar Lentigines

Solar lentigines (SLs) are a hallmark of human skin aging. They result from chronic exposure to sunlight and other environmental stressors. Recent studies also imply genetic factors, but findings are partially conflicting and lack of replication. Through a multi-trait based analysis strategy, we discovered that genetic variants in telomerase reverse transcriptase were significantly associated with non-facial SL in two East Asian (Taizhou longitudinal cohort, n = 2,964 and National Survey of Physical Traits, n = 2,954) and one Caucasian population (SALIA, n = 462), top SNP rs2853672 (P-value for Taizhou longitudinal cohort = 1.32 × 10^‒28 and P-value for National Survey of Physical Traits = 3.66 × 10^‒17 and P-value for SALIA = 0.0007 and P_meta = 4.93 × 10^‒44). The same variants were nominally associated with facial SL but not with other skin aging or skin pigmentation traits. The SL-enhanced allele/haplotype upregulated the transcription of the telomerase reverse transcriptase gene. Of note, well-known telomerase reverse transcriptase‒related aging markers such as leukocyte telomere length and intrinsic epigenetic age acceleration were not associated with SL. Our results indicate a previously unrecognized role of telomerase reverse transcriptase in skin aging‒related lentigines formation.

Associations between TERT Promoter Mutations and Survival in Superficial Spreading and Nodular Melanomas in a Large Prospective Patient Cohort

Survival outcomes in melanoma and their association with mutations in the telomerase reverse transcriptase gene TERT promoter remain uncertain. In addition, few studies have examined whether these associations are affected by a nearby common germline polymorphism or vary on the basis of melanoma histopathological subtype. We analyzed 408 primary tumors from a prospective melanoma cohort for somatic TERT-124[C>T] and TERT-146[C>T] mutations, the germline polymorphism rs2853669, and BRAFV600 and NRASQ61 mutations. We tested the associations between these variants and clinicopathologic factors and survival outcomes. TERT-124[C>T] was associated with thicker tumors, ulceration, mitoses (>0/mm2), nodular histotype, and CNS involvement. In a multivariable model controlling for the American Joint Committee on Cancer stage, TERT-124[C>T] was an independent predictor of shorter recurrence-free survival (hazard ratio = 2.58, P = 0.001) and overall survival (hazard ratio = 2.47, P = 0.029). Patients with the germline variant and TERT-124[C>T]-mutant melanomas had significantly shorter recurrence-free survival than those lacking either or both sequence variants (P < 0.04). The impact of the germline variant appeared to be more pronounced in superficial spreading than in nodular melanoma. No associations were found between survival and TERT-146[C>T], BRAF, or NRAS mutations. These findings strongly suggest that TERT-124[C>T] mutation is a biomarker of aggressive primary melanomas, an effect that may be modulated by rs2853669.

CTNNB1 mutations, TERT polymorphism and CD8+ cell densities in resected hepatocellular carcinoma are associated with longer time to recurrence

Background

Hepatocellular carcinoma (HCC) is a fatal disease characterized by early genetic alterations in telomerase reverse transcriptase promoter (TERTp) and β-catenin (CTNNB1) genes and immune cell activation in the tumor microenvironment. As a novel approach, we wanted to assess patient survival influenced by combined presence of mutations and densities of CD8+ cytotoxic T cells.

Methods

Tissue samples were obtained from 67 HCC patients who had undergone resection. We analysed CD8+ T cells density, TERTp mutations, rs2853669 polymorphism, and CTNNB1 mutations. These variables were evaluated for time to recurrence (TTR) and disease free survival (DFS).

Results

TERTp mutations were found in 75.8% and CTNNB1 mutations in 35.6% of the patients. TERTp mutations were not associated with survival but polymorphism rs2853669 in TERTp was associated with improved TTR and DFS. CTNNB1 mutations were associated with improving TTR. High density of CD8+ T-lymphocytes in tumor center and invasive margin correlated with longer TTR and DFS. Combined genetic and immune factors further improved survival showing higher predictive values. E.g., combining CTNNB1 mutations and high density of CD8+ T-lymphocytes in tumor center yielded HRs of 0.12 (0.03–0.52), p = 0.005 for TTR and 0.25 (0.09–0.74), p = 0.01 for DFS.

Conclusion

The results outline a novel integrative approach for prognostication through combining independent predictive factors from genetic and immune cell profiles. However, larger studies are needed to explore multiple cell types in the tumor microenvironment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09989-0.

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.

Anchored Multiplex PCR Custom Melanoma Next Generation Sequencing Panel for Analysis of Circulating Tumor DNA

Detection of melanoma mutations using circulating tumor DNA (ctDNA) is a potential alternative to using genomic DNA from invasive tissue biopsies. To date, mutations in the GC-rich TERT promoter region, which is commonly mutated in melanoma, have been technically difficult to detect in ctDNA using next-generation sequencing (NGS) panels. In this study, we developed a custom melanoma NGS panel for detection of ctDNA, which encompasses the top 15 gene mutations in melanoma including the TERT promoter. We analyzed 21 stage III and IV melanoma patient samples who were treatment-naïve or on therapy. The overall detection rate of the custom panel, based on BRAF/NRAS/TERT promoter mutations, was 14/21 (67%) patient samples which included a TERT C250T mutation in one BRAF and NRAS mutation negative sample. A BRAF or NRAS mutation was detected in the ctDNA of 13/21 (62%) patients while TERT promoter mutations were detected in 10/21 (48%) patients. Co-occurrence of TERT promoter mutations with BRAF or NRAS mutations was found in 9/10 (90%) patients. The custom ctDNA panel showed a concordance of 16/21 (76%) with tissue based-detection and included 12 BRAF/NRAS mutation positive and 4 BRAF/NRAS mutation negative patients. The ctDNA mutation detection rate for stage IV was 12/16 (75%) and for stage III was 1/5 (20%). Based on BRAF, NRAS and TERT promoter mutations, the custom melanoma panel displayed a limit of detection of ~0.2% mutant allele frequency and showed significant correlation with droplet digital PCR. For one patient, a novel MAP2K1 H119Y mutation was detected in an NRAS/BRAF/TERT promoter mutation negative background. To increase the detection rate to >90% for stage IV melanoma patients, we plan to expand our custom panel to 50 genes. This study represents one of the first to successfully detect TERT promoter mutations in ctDNA from cutaneous melanoma patients using a targeted NGS panel.

Fas -670 A/G polymorphism predicts prognosis of hepatocellular carcinoma after curative resection in Chinese Han population

BACKGROUND

Apoptosis, also called programmed cell death, is a genetically controlled process against hyperproliferation and malignancy. The Fas-Fas ligand (FasL) system is considered a major pathway for apoptosis in cells and tissues. Thus, this study aimed to investigate whether single nucleotide polymorphisms (SNPs) in Fas and FasL gene may have effects on the recurrence and survival of patients with hepatocellular carcinoma (HCC) after curative hepatectomy.

METHODS

We investigated the relationship between Fas rs1800682, rs2234767 and FasL rs763110 polymorphisms and recurrence-free survival (RFS) as well as overall survival (OS) in 117 Chinese Han patients with HCC who underwent hepatectomy.

RESULTS

In Kaplan-Meier survival analysis, only Fas rs1800682 (-670 A/G) was associated with RFS and OS. Compared with AA genotype, the AG/GG genotype was significantly associated with better RFS (P = 0.008) and OS (P = 0.020). Moreover, multivariate Cox regression analysis showed that Fas rs1800682 remained as a significant independent predictor of RFS for HCC patients with hepatectomy [AG/GG vs. AA: adjusted hazard ratio = 0.464, 95% confidence interval: 0.275-0.782, P = 0.004], but was not an independent predictor of OS (P = 0.395).

CONCLUSIONS

This study demonstrated that Fas -670 G allele may play a protective role in the recurrence and survival of HCC patients with hepatectomy. Furthermore, Fas rs1800682 polymorphism might be a promising biomarker for HCC patients after hepatectomy.

TERT Promoter Mutations and rs2853669 Polymorphism: Useful Markers for Clinical Outcome Stratification of Patients With Oral Cavity Squamous Cell Carcinoma

Objective

To date, no useful prognostic biomarker exists for patients with oral squamous cell carcinoma (OCSCC), a tumour with uncertain biological behaviour and subsequent unpredictable clinical course. We aim to investigate the prognostic significance of two recurrent somatic mutations (-124 C>T and -146 C>T) within the promoter of telomerase reverse transcriptase (TERT) gene and the impact of TERT single nucleotide polymorphism (SNP) rs2853669 in patients surgically treated for OCSCC.

Methods

The genetic frequencies of rs2853669, -124 C>T and -146 C>T as well as the telomere length were investigated in 144 tumours and 57 normal adjacent mucosal (AM) specimens from OCSCC patients.

Results

Forty-five tumours harboured TERT promoter mutations (31.3%), with -124 C>T and -146 C>T accounting for 64.4% and 35.6% of the alterations respectively. Patients with -124 C>T TERT promoter mutated tumours had the shortest telomeres in the AM (p=0.016) and showed higher risk of local recurrence (hazard ratio [HR]:2.75, p=0.0143), death (HR:2.71, p=0.0079) and disease progression (HR:2.71, p=0.0024) with the effect being potentiated by the co-occurrence of T/T genotype of rs2853669.

Conclusion

-124 C>T TERT promoter mutation as well as the T/T genotype of the rs2853669 SNP are attractive independent prognostic biomarkers in patients surgically treated for OCSCC, with the coexistence of these genetic variants showing a synergistic impact on the aggressiveness of the disease.

Exploring the Interplay of Telomerase Reverse Transcriptase and β-Catenin in Hepatocellular Carcinoma

Simple Summary

Liver cancer is one of the deadliest human cancers. Two of the most common molecular aberrations in liver cancer are: (1) activating mutations in the gene encoding β-catenin (CTNNB1); and (2) promoter mutations in telomerase reverse transcriptase (TERT). Here, we review recent findings regarding the interplay between TERT and β-catenin in order to better understand their role in liver cancer.

Abstract

Hepatocellular carcinoma (HCC) is one of the deadliest human cancers. Activating mutations in the telomerase reverse transcriptase (TERT) promoter (TERTp) and CTNNB1 gene encoding β-catenin are widespread in HCC (~50% and ~30%, respectively). TERTp mutations are predicted to increase TERT transcription and telomerase activity. This review focuses on exploring the role of TERT and β-catenin in HCC and the current findings regarding their interplay. TERT can have contradictory effects on tumorigenesis via both its canonical and non-canonical functions. As a critical regulator of proliferation and differentiation in progenitor and stem cells, activated β-catenin drives HCC; however, inhibiting endogenous β-catenin can also have pro-tumor effects. Clinical studies revealed a significant concordance between TERTp and CTNNB1 mutations in HCC. In stem cells, TERT acts as a co-factor in β-catenin transcriptional complexes driving the expression of WNT/β-catenin target genes, and β-catenin can bind to the TERTp to drive its transcription. A few studies have examined potential interactions between TERT and β-catenin in HCC in vivo, and their results suggest that the coexpression of these two genes promotes hepatocarcinogenesis. Further studies are required with vertebrate models to better understand how TERT and β-catenin influence hepatocarcinogenesis.

Clinicopathological Significance of BRAF (V600E), NRAS (Q61K) and TERT (C228T, C250T and SNP Rs2853669) Mutations in Bulgarian Papillary Thyroid Carcinoma Patients

Introduction: Thyroid carcinoma is the most common endocrine cancer. Some somatic mutations in genes (BRAF, NRAS and TERT) involved in key signaling pathways and genome stability have been recently identified to play an important role in its development. Very little research has been done on their frequency and clinical relevance in Bulgarian patients with papillary thyroid cancer (PTC). This study is focused on investigating somatic mutation frequency in Bulgarian patients with PTC and their association with clinicopathologic features.

Material and Methods: The study included 50 PTC from Bulgarian patients analyzed for mutations in BRAF (V600E), NRAS (Q61K), single nucleotide polymorphism (SNP) rs2853669 and TERT (C228T and C250T) genes by Sanger sequencing. The results were interpreted using Benchling and SeqScape software, and statistical analysis performed with SPSS.

Results: In the studied PTC group BRAF(V600E) and TERT (C228T) mutations were found with frequency of 24% and 2%, respectively. Co-occurrence of both mutations was found in 1 patient (2%). The mutations Q61K (NRAS), and C250T (TERT) were not detected. The SNP rs2853669 was found in 18 patients (52.9%). Correlation analysis with the clinical characteristics of the patients revealed statistically significant association with larger size of the tumor for BRAF(V600E) and smaller tumor size for rs2853669.

Conclusion: In the present pilot study, we found that BRAF(V600E) and rs2853669 in TERT are common among PCT patients. While the presence of BRAF V600E mutation was associated with large tumors, the presence of rs2853669 in TERT was found in the majority of PCT below 2 cm. More extensive molecular genetic analysis of TERT, BRAF or RAS mutations in larger sample is needed to further elucidate the clinically important diagnostic and prognostic biomarkers for thyroid cancer.

Regulatory Single Nucleotide Polymorphism Increases TERT Promoter Activity in Thyroid Carcinoma Cells

BACKGROUND/AIM

The telomerase reverse transcriptase (TERT) promoter has a regulatory single nucleotide polymorphism (rSNP), rs2853669, and occasionally shows point mutations C228T and C250T. Although C228T and C250T have been well examined to increase TERT promoter activity and are known as risk factors for thyroid carcinoma, the significance of rs2853669 has not been well investigated. This study aimed to clarify the influence of rs2853669 on TERT promoter activity in thyroid carcinoma cells.

MATERIALS

Seven of 8 examined thyroid cell lines had rs2853669, 5 had C228T, and 1 had C250T.

RESULTS

Three papillary thyroid carcinoma cell lines, harboring both rs2853669 and C228T, showed higher TERT mRNA expression on real-time PCR than the other cell lines. Anaplastic thyroid carcinoma cell lines, in contrast, showed variable TERT mRNA expression depending on the combination of rs2853669, C228T, and C250T. Luciferase assays, performed to compare the influences of rs2853669, C228T, and C250T on TERT promoter activity in thyroid carcinoma, showed that rs2853669, as well as C228T, increased the promoter activity, and the combination of rs2853669 and C228T increased the promoter activity even more strongly than C228T alone.

CONCLUSION

We conclude that the presence of rs2853669 within the TERT promoter could be as significant as the C228T mutation in thyroid carcinoma.

Telomeres and Telomerase in the Development of Liver Cancer

Liver cancer is one of the most common cancer types worldwide and the fourth leading cause of cancer-related death. Liver carcinoma is distinguished by a high heterogeneity in pathogenesis, histopathology and biological behavior. Dysregulated signaling pathways and various gene mutations are frequent in hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA), which represent the two most common types of liver tumors. Both tumor types are characterized by telomere shortening and reactivation of telomerase during carcinogenesis. Continuous cell proliferation, e.g., by oncogenic mutations, can cause extensive telomere shortening in the absence of sufficient telomerase activity, leading to dysfunctional telomeres and genome instability by breakage-fusion-bridge cycles, which induce senescence or apoptosis as a tumor suppressor mechanism. Telomerase reactivation is required to stabilize telomere functionality and for tumor cell survival, representing a genetic risk factor for the development of liver cirrhosis and liver carcinoma. Therefore, telomeres and telomerase could be useful targets in hepatocarcinogenesis. Here, we review similarities and differences between HCC and iCCA in telomere biology.

ETS variant transcription factor 5 and c-Myc cooperate in derepressing the human telomerase gene promoter via composite ETS/E-box motifs

The human telomerase gene (hTERT) is repressed in most somatic cells. How transcription factors activate the hTERT promoter in its repressive chromatin environment is unknown. Here, we report that the ETS family protein ETS variant transcription factor 5 (ETV5) mediates epidermal growth factor (EGF)-induced hTERT expression in MCF10A cells. This activation required MYC proto-oncogene bHLH transcription factor (c-Myc) and depended on the chromatin state of the hTERT promoter. Using chromatinized bacterial artificial chromosome (BAC) reporters in human fibroblasts, we found that ETV5 and c-Myc/MYC-associated factor X (MAX) synergistically activate the hTERT promoter via two identical, but inverted, composite Ets/E-box motifs enclosing the core promoter. Mutations of Ets or E-box sites in either DNA motif abolished the activation and reduced or eliminated the synergism. ETV5 and c-Myc facilitated each other's binding to the hTERT promoter. ETV5 bound to the hTERT promoter in both telomerase-negative and -positive cells, but it activated the repressed hTERT promoter and altered histone modifications only in telomerase-negative cells. The synergistic ETV5/c-Myc activation disappeared when hTERT promoter repression became relieved because of the loss of distal regulatory elements in chimeric human/mouse BAC reporters. Our results suggest that the binding of c-Myc and ETS family proteins to the Ets/E-box motifs derepresses the hTERT promoter by inducing an active promoter configuration, providing a mechanistic insight into hTERT activation during tumorigenesis.

A Static Magnetic Field Inhibits the Migration and Telomerase Function of Mouse Breast Cancer Cells

Static magnetic field (SMF) has a potential as a cancer therapeutic modality due to its specific inhibitory effects on the proliferation of multiple cancer cells. However, the underlying mechanism remains unclear, and just a few studies have examined the effects of SMF on metastasis, an important concern in cancer treatment. In this study, we evaluated the effects of moderate SMF (~150 mT) on the proliferation and migration of 4T1 breast cancer cells. Our results showed that SMF treatment accelerated cell proliferation but inhibited cell migration. Further, SMF treatment shortened the telomere length, decreased telomerase activity, and inhibited the expression of the cancer-specific marker telomerase reverse transcriptase (TERT), which may be related to expression upregulation of e2f1, a transcription repressor of TERT and positive regulator of the mitotic cell cycle. Our results revealed that SMF repressed both, cell migration and telomerase function. The telomerase network is responsive to SMF and may be involved in SMF-mediated cancer-specific effects; moreover, it may function as a therapeutic target in magnetic therapy of cancers.

TERT Promoter Mutations Differently Correlate with the Clinical Outcome of MAPK Inhibitor-Treated Melanoma Patients

Resistance is a major challenge in the management of mitogen-activated protein kinase inhibitor (MAPKi)-treated metastatic melanoma. Tumor genetic alterations can cause MAPK pathway reactivation, leading to lack of response and poor outcome. Characterization of the mutational profile in patients with melanoma might be crucial for patient-tailored treatment choices. Mutations in the promoter region of the telomerase reverse transcriptase gene (TERTprom) lead to increased TERT expression and telomerase activity and are frequent in BRAF^V600 mutant melanoma. Reportedly, TERTprom, and BRAF^V600 mutations cooperate in driving cancer progression and aggressiveness. We evaluated the effect of the TERTprom status on the clinical outcome in 97 MAPKi-treated melanoma patients. We observed that patients with the c.-146C > T mutation showed a significantly worse progression-free survival (PFS) compared to those carrying the c.-124C > T mutation and a two-fold increased risk of progression (median 5.4 vs. 9.5 months; hazard ratio (HR) 1.9; 95% confidence interval (CI) 1.2–3.2; p = 0.013). This trend was also observed for the overall survival (OS); melanoma patients with the c.-146C > T mutation showed a poorer prognosis compared to those with the c.-124C > T mutation (median 13.3 vs. 25.5 months; HR 1.9, 95% CI 1.1–3.3, p = 0.023). Our results disclose a different correlation of the two TERTprom mutations with MAPKi-treated melanoma patient outcome, highlighting a different impact of the pathway blockade.

The Solo Play of TERT Promoter Mutations

The reactivation of telomerase reverse transcriptase (TERT) protein is the principal mechanism of telomere maintenance in cancer cells. Mutations in the TERT promoter (TERTp) are a common mechanism of TERT reactivation in many solid cancers, particularly those originating from slow-replicating tissues. They are associated with increased TERT levels, telomere stabilization, and cell immortalization and proliferation. Much effort has been invested in recent years in characterizing their prevalence in different cancers and their potential as biomarkers for tumor stratification, as well as assessing their molecular mechanism of action, but much remains to be understood. Notably, they appear late in cell transformation and are mutually exclusive with each other as well as with other telomere maintenance mechanisms, indicative of overlapping selective advantages and of a strict regulation of TERT expression levels. In this review, we summarized the latest literature on the role and prevalence of TERTp mutations across different cancer types, highlighting their biased distribution. We then discussed the need to maintain TERT levels at sufficient levels to immortalize cells and promote proliferation while remaining within cell sustainability levels. A better understanding of TERT regulation is crucial when considering its use as a possible target in antitumor strategies.

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.

TERT Promoter Mutation as a Potential Predictive Biomarker in BCG-Treated Bladder Cancer Patients

Telomerase reverse transcriptase gene promoter (TERTp) mutations are recognized as one of the most frequent genetic events in bladder cancer (BC). No studies have focused on the relevance of TERTp mutations in the specific group of tumors treated with Bacillus Calmette–Guérin (BCG) intravesical therapy. Methods — 125 non muscle invasive BC treated with BCG therapy (BCG-NMIBC) were screened for TERTp mutations, TERT rs2853669 single nucleotide polymorphism, and Fibroblast Growth Factor Receptor 3 (FGFR3) hotspot mutations. Results — TERTp mutations were found in 56.0% of BCG-NMIBC and were not associated with tumor stage or grade. FGFR3 mutations were found in 44.9% of the cases and were not associated with tumor stage or grade nor with TERTp mutations. The TERT rs2853669 single nucleotide polymorphism was associated with tumors of higher grade. The specific c.1-146G>A TERTp mutation was an independent predictor of nonrecurrence after BCG therapy (hazard ratio—0.382; 95% confidence interval—0.150–0.971, p = 0.048). Conclusions — TERTp mutations are frequent in BCG-NMIBC and -146G>A appears to be an independent predictive marker of response to BCG treatment with an impact in recurrence-free survival.

Frequency of somatic mutations in TERT promoter, TP53 and CTNNB1 genes in patients with hepatocellular carcinoma from Southern Italy

Somatic mutations in the TERT promoter and in the TP53 and CTNNB1 genes are considered drivers for hepatocellular carcinoma (HCC) development. They show variable frequencies in different geographic areas, possibly depending on liver disease etiology and environmental factors. TP53, CTNNB1 and TERT genetic mutations were investigated in tumor and non-tumor liver tissues from 67 patients with HCC and liver tissue specimens from 41 control obese subjects from Southern Italy. Furthermore, TERT expression was assessed by reverse transcription-quantitative PCR. Neither CTNNB1 mutations or TP53 R249S substitution were detected in any case. The TP53 R72P polymorphism was found in 10/67 (14.9%) tumors, but was not found in either non-tumor tissues (P=0.001) or controls (P=0.009). TERT gene promoter mutations were found in 29/67 (43.3%) tumor tissues but were not found in either non-tumor (P<0.0001) or control liver specimens (P<0.0001). The most frequent mutation in the tumors was the known hot spot at -124 bp from the TERT ATG start site (-124G>A, 28 cases, 41.8%; P<0.0001). A new previously never reported TERT promoter mutation (at -297 bp from the ATG, -297C>T) was found in 5/67 (7.5%) tumors, in 0/67 (0%) non-tumor (P<0.0001), and in 0/41 (0%) controls (P=0.07). This mutation creates an AP2 consensus sequence, and was found alone (1 case) or in combination (4 cases) with the -124 bp mutation. The mutation at -124 and -297 bp induced a 33-fold (P<0.0001) and 40-fold increase of TERT expression levels, respectively. When both mutations were present, TERT expression levels were increased >300-fold (P=0.001). A new TERT promoter mutation was identified, which generates a de novo binding motif for AP2 transcription factors, and which significantly increases TERT promoter transcriptional activity.

Clinicopathological significance of the single nucleotide polymorphism, rs2853669 within the TERT promoter in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy. Point mutations in the telomerase reverse transcriptase (TERT) promoter, C228T and C250T and oncogene BRAF^V600E have been investigated as risk factors for PTC. However, little research has been done on the single nucleotide polymorphism rs2853669 in the TERT promoter in PTC. This study aimed to clarify the clinicopathological significance of rs2853669 in Japanese patients with PTC. The genetic frequencies of rs2853669, C228T, C250T and BRAF^V600E were investigated in 58 patients with PTC and compared with the clinicopathological parameters of PTC. rs2853669, C228T, C250T and BRAF^V600E were found in 58.6%, 17.2%, 5.2% and 37.0% of the PTC patients, respectively. PTC with rs2853669 and C228T were associated only with tumor sizes larger than 2.0 cm (P < 0.05). Furthermore, the coexistence of rs2853669 and C228T was strongly associated with tumor size (P < 0.01), with an odds ratio of 6.4 (P < 0.05). We showed that rs2853669, as well as C228T, may be a risk factor for the aggressiveness of PTC, and the coexistence of these mutations might represent greater risk.

Effect of single-nucleotide polymorphism in TERT promoter on follicular thyroid tumor development

Follicular thyroid neoplasm is a common tumor, and consists of follicular thyroid adenoma (FTA) and carcinoma (FTC). The mechanisms of tumor development of FTA and FTC are not well-understood. Single-nucleotide polymorphisms (SNPs) and point mutations in the telomerase reverse transcriptase (TERT) promoter have been associated with tumor development of many cancers. In order to clarify the significance of TERT promoter SNPs and mutations, including rs2853669 (-245T>C), C228T, and C250T, we analyzed 59 FTA patients and 19 FTC patients. Rs2853669 was found in 67.8% (40/59) and 57.9% (11/19) of FTAs and FTCs, respectively, and homozygous rs2853669 (CC) was more frequently found in FTC than in FTA. Furthermore, in FTA, rs2853669 was significantly associated with tumor size greater than 2.0 cm (P < 0.05). C228T was found in 5.1% and 36.8% of FTAs and FTCs, respectively. Frequencies of rs2853669 or/and C228T mutation were 71.2% in FTAs and 73.7%, in FTCs, and were significantly associated with larger tumor sizes in FTAs (P < 0.05). Rs2853669 is considered to be associated with tumor development in FTA and FTC.

The role of telomeres and telomerase in cirrhosis and liver cancer

Telomerase is a key enzyme for cell survival that prevents telomere shortening and the subsequent cellular senescence that is observed after many rounds of cell division. In contrast, inactivation of telomerase is observed in most cells of the adult liver. Absence of telomerase activity and shortening of telomeres has been implicated in hepatocyte senescence and the development of cirrhosis, a chronic liver disease that can lead to hepatocellular carcinoma (HCC) development. During hepatocarcinogenesis, telomerase reactivation is required to enable the uncontrolled cell proliferation that leads to malignant transformation and HCC development. Part of the telomerase complex, telomerase reverse transcriptase, is encoded by TERT, and several mechanisms of telomerase reactivation have been described in HCC that include somatic TERT promoter mutations, TERT amplification, TERT translocation and viral insertion into the TERT gene. An understanding of the role of telomeres and telomerase in HCC development is important to develop future targeted therapies and improve survival of this disease. In this Review, the roles of telomeres and telomerase in liver carcinogenesis are discussed, in addition to their potential translation to clinical practice as biomarkers and therapeutic targets.

Identification of genes involved in the regulation of TERT in hepatocellular carcinoma

Telomerase reverse transcriptase (TERT) promotes immortalization by protecting telomeres in cancer cells. Mutation of the TERT promoter is one of the most common genetic alterations in hepatocellular carcinoma (HCC), indicating that TERT upregulation is a critical event in hepatocarcinogenesis. Regulators of TERT transcription are, therefore, predicted to be plausible targets for HCC treatment. We undertook a genome‐wide shRNA library screen and identified C15orf55 and C7orf43 as regulators of TERT expression in HepG2 cells. Promoter assays showed that C15orf55‐ and C7orf43‐responsive sites exist between base pairs −58 and +36 and −169 and −59 in the TERT promoter, respectively. C15orf55 upregulates TERT expression by binding to two GC motifs in the SP1 binding site of the TERT promoter. C7orf43 upregulates TERT expression through Yes‐associated protein 1. The expression levels of C15orf55 and C7orf43 also correlated with that of TERT, and were significantly increased in both HCC tissues and their adjacent non‐tumor tissues, compared to normal liver tissues from non‐HCC patients. Analysis of 377 HCC patients in The Cancer Genome Atlas dataset showed that overall survival of patients with low levels of C15orf55 and C7orf43 expression in tumor tissues was better compared with patients with high levels of C15orf55 and/or high C7orf43 expression. These results indicate that C15orf55 and C7orf43 are involved in the incidence and progression of HCC by upregulating TERT. In conclusion, we identified C15orf55 and C7orf43 as positive regulators of TERT expression in HCC tissues. These genes are promising targets for HCC treatment.

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.

Telomere length and reactive oxygen species levels are positively associated with a high risk of mortality and recurrence in hepatocellular carcinoma

Telomeres protect chromosomal ends from deterioration and have been shown to be susceptible to shortening by reactive oxygen species (ROS)-induced damage. ROS levels increase during the progression from early to advanced hepatocellular carcinoma (HCC). An independent study found that the telomeres in most HCC tissues lengthened during carcinogenic advancement. Activated telomerase has been hypothesized to elongate telomeres during the progression of malignant HCC, but it remains unclear which signaling pathway is necessary for telomerase activation in HCC. Here, we showed using cell lines derived from human HCC that H₂ O₂ , which is a major component of ROS in living organisms, elongates telomeres by increasing telomerase activity through protein kinase B (AKT) activation. The AKT inhibitor, perifosine, decreased telomere length, cellular viability, and H₂ O₂ -mediated migration and invasion capacity in HCC cells while also inhibiting AKT activation, telomere maintenance, and tumor growth in nude mice. Advanced HCC tissues showed a positive correlation among ROS levels, phosphorylated AKT (pAKT) levels, and telomere length. Furthermore, patients with HCC tumors that have high ROS levels and long telomeres displayed poorer survival rates. These data demonstrate the significant utilities of ROS levels, pAKT levels, and telomere length for predicting a poor prognosis in patients with HCC. Taken together, AKT activation could be essential for telomere maintenance in advanced HCC tumors as well as being an important contributor to malignant HCC progression.

CONCLUSION

We showed that H₂ O₂ contributes to telomere elongation through AKT activation in advanced HCC, suggesting that an AKT inhibitor such as perifosine may be useful for treating patients with malignant HCC. (Hepatology 2018;67:1378-1391).

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.

Tumor specific mutations in TERT promoter and CTNNB1 gene in hepatitis B and hepatitis C related hepatocellular carcinoma

Recurrent somatic mutations in the promoter region of telomerase reverse transcriptase (TERT) gene and in the exon 3 of CTNNB1 gene have been recognized as common events in hepatocellular carcinoma (HCC) with variable frequencies depending on etiology and geographical region. We have analyzed TERT promoter and CTNNB1 gene mutations in 122 cases of hepatitis B (HBV) and hepatitis C (HCV) related HCCs, in 7 cases of cholangiocarcinoma (CC) and hepatocholangiocarcinoma (HCC-CC) as well as in autologous cirrhotic tissues. Overall, 50.4% and 26% of HCC as well as 14.3% and none of CC and HCC-CC were mutated in TERT promoter and in CTNNB1 exon 3, respectively. TERT and CTNNB1 mutations were found more frequently in HCV related (53.6% and 26.4%, respectively) than HBV related (41.7% and 16.7%, respectively) HCCs and coexisted in 57.6% of CTNNB1 mutated tumors. Mutations in TERT and CTNNB1 were not associated with the functional promoter polymorphism rs2853669. No mutations were detected in the 129 non-HCC cirrhotic tissues. In conclusion, mutations in TERT promoter and in CTNNB1 gene represent specific cancer signatures in the pathogenesis of viral related HCC and could be promising early biomarkers as well as targets for tailored therapies.

Combining molecular and immunohistochemical analyses of key drivers in primary melanomas: interplay between germline and somatic variations

Due to the high mutational somatic burden of Cutaneous Malignant Melanoma (CMM) a thorough profiling of the driver mutations and their interplay is necessary to explain the timing of tumorigenesis or for the identification of actionable genetic events. The aim of this study was to establish the mutation rate of some of the key drivers in melanoma tumorigenesis combining molecular analyses and/or immunohistochemistry in 93 primary CMMs from an Italian cohort also characterized for germline status, and to investigate an interplay between germline and somatic variants. BRAF mutations were present in 68% of cases, while CDKN2A germline mutations were found in 16 % and p16 loss in tissue was found in 63%. TERT promoter somatic mutations were detected in 38% of cases while the TERT -245T>C polymorphism was found in 51% of cases. NRAS mutations were found in 39% of BRAF negative or undetermined cases. NF1 was expressed in all cases analysed. MC1R variations were both considered as a dichotomous variable or scored. While a positive, although not significant association between CDKN2A germline mutations, but not MC1R variants, and BRAF somatic mutation was found, we did not observe other associations between germline and somatic events. A yet undescribed inverse correlation between TERT -245T>C polymorphism and the presence of BRAF mutation was found. It is possible to hypothesize that -245T>C polymorphism could be included in those genotypes which may influence the occurrence of BRAF mutations. Further studies are needed to investigate the role of -245T>C polymorphism as a germline predictor of BRAF somatic mutation status.

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.

Polymorphisms in matrix metalloproteinases 2, 3, and 8 increase recurrence and mortality risk by regulating enzyme activity in gastric adenocarcinoma

The association of polymorphisms in matrix metalloproteinases (MMPs) with clinical outcomes of gastric adenocarcinoma has not been examined. Ten polymorphisms in MMP1, 2, 3, 7, 8, 9, 12, and 13 were genotyped and investigated, and patients were followed for an average of 58 months. The activities of MMP2, 3, and 8 were measured. Recurrence risk increased in patients with the MMP2 rs2285053 CC genotype (hazard ratio [HR], 1.85), MMP3 rs679620 AA genotype (HR, 2.15), and MMP8 rs1940475 TT genotype (HR, 2.22) on recurrence free survival (RFS). Co-presence of the unfavorable MMP2 rs2285053 CC and MMP8 rs1940475 TT genotypes resulted in an additional increased risk of recurrence (RFS: HR, 4.42; 95% confidence interval [CI], 2.15-9.09; p<0.0001) and risk of death (overall survival ( OS) : HR, 6.59; 95% CI, 3.15-13.19; p<0.0001). Theoretical survival tree analysis revealed that recurrence-free survival significantly varied from 15.5 to 87 months among patients with different polymorphisms in MMP2, 3, and 8. The enzymatic activities of MMP2 and MMP3 increased (MMP2 rs2285053 CC: 888.60 vs. CT: 392.00, p <0.0001; MMP3 rs679620 AA: 131.10 vs. GG: 107.74, p=0.015), whereas those of MMP8 decreased (MMP8 rs1940475 TT: 133.78 vs. CC: 147.54, p=0.011) in gastric cancer tissues. These results suggest that polymorphisms in MMP2, 3, and 8 may increase cancer recurrence and patient death by increasing or decreasing enzyme activity in patients with gastric adenocarcinoma.

Preclinical and clinical implications of TERT promoter mutation in glioblastoma multiforme

The promoter region of the telomerase reverse transcriptase gene (TERT) is mutated in a subpopulation of patients with glioblastoma multiforme (GBM). In the present study, preclinical and clinical implications of the mutation were analyzed in 25 GBMs to evaluate its utility as a therapeutic target. Associations between the TERT promoter mutation and a number of preclinical/clinical characteristics were analyzed. Notably, the TERT promoter mutation was identified in 92.3% of GBMs where dissociated cells revealed in vitro sphere formation capacity; while the TERT promoter mutation was identified in 33.3% of GBMs without in vitro sphere formation capacity (P=0.004). In addition, this significantly increased mutation rate was observed in GBMs with in vivo tumorigenic potential (80% vs. 0%; P=0.004). Furthermore, patients with GBM exhibiting the TERT promoter mutation demonstrated significantly decreased overall survival rate compared with patients lacking this mutation (81.7 vs. 152.6 weeks; P=0.026). The results of the present study indicated that the TERT promoter mutation is associated with the self-renewal capacity of GBM cells and clinical aggressiveness of GBMs, which may be translated to a targeting therapy against TERT to inhibit the self-renewal of GBM cells.

A novel SNP in promoter region of RP11-3N2.1 is associated with reduced risk of colorectal cancer

Single-nucleotide polymorphisms (SNPs) in the promoter region of long intergenic non-coding RNAs (lincRNAs) could play a regulatory role in its expression level and then get involved in colorectal cancer (CRC). Thus, we conducted a two-stage case-control study to investigate the associations of Tag SNPs within the promoter region of selected lincRNAs from microarray data with risk of CRC. A total of 320 cases and 319 controls were recruited in the test set to explore the associations between 16 SNPs with no deviations from Hardy-Weinberg equilibrium (HWE) and risk of CRC. Furthermore, 501 cases and 538 controls were included as the validation set to confirm the significant associations. RP11-3N2.1 rs13230517 polymorphism was found to be negatively associated with CRC in both test set (AA vs. GG, OR = 0.68, 95% CI = 0.48-0.96) and validation set (AA vs. GG, OR = 0.76, 95% CI = 0.59-0.98). Pooled analysis showed that individuals with GA/AA genotypes had a significantly decreased risk of CRC when compared with those carrying GG genotype (OR = 0.74, 95% CI = 0.60-0.90) in the combined set. The crossover analysis revealed that rs13230517 GA/AA carriers had a decreased risk of CRC than GG carriers among non-drinkers in both test and combined set. However, no gene-environment multiplicative interactions were found on risk of CRC. Our findings suggest that rs13230517 polymorphism might participate in the pathogenesis of CRC and have the potential to be a biomarker for predicting the risk of CRC.

TERT-CLPTM1 locus polymorphism (rs401681) is associated with the prognosis of hepatocellular carcinoma

Telomere length is associated with the development of hepatocellular carcinoma (HCC), and recent studies have focused on the genetic alteration or polymorphism in telomere-maintaining genes. We examined the clinicopathologic and prognostic value of rs401681 polymorphism, located in the TERT-CLPTM1L locus, in HCC. The relationship between rs401681 variants and telomere length was also analyzed in 156 HCC patients. The rs401681 polymorphism had the following genotype frequencies: C/C in 51.3% of the samples, C/T in 39.7%, and T/T in 9.0%. Telomeres in the tumor samples were 4.04-fold longer, on average, than the telomeres in matched normal samples (SD =1.32), and there were no differences in telomere length according to rs401681 polymorphism (p=0.802). Our results indicate that the rs401681 C allele was significantly associated with increased T and International Union for Cancer Control stages (p<0.01). Univariate and multivariate survival analyses showed that HCC with C allele had poorer prognosis (p<0.01). In conclusion, our findings suggest that rs401681 is a possible prognostic biomarker for HCC patients.

Clinical importance of TERT overexpression in hepatocellular carcinoma treated with curative surgical resection in HBV endemic area

This study was designed to investigate the associations between TERT overexpression and the clinicopathologic factors of hepatocellular carcinoma (HCC). A total of 291 patients with HCC were enrolled. The site of first recurrence (anywhere in the liver) was classified as intrahepatic recurrence (IHR). Recurrence was then sub classified as either early or late IHR according to whether it was discovered within 2 years of resection, or after, respectively. TERT overexpression was not significantly correlated with previously recognized prognostic factors. During follow-up, early IHR occurred in 126 (63.6%) patients, while late IHR was detected in 59 patients among 145 patients who remained free of HCC recurrence for ≥ 2 years after surgery. Multivariate analysis showed late IHR was significantly correlated with TERT overexpression (P < 0.001, hazard ratio [HR] 2.67, 95% confidence interval [CI] 1.51–4.72). Intrahepatic metastasis (P < 0.001, HR 4.48, 95% CI 2.62–7.65) and TERT overexpression (P < 0.001, HR 1.77, 95% CI 1.28–2.45) were significant prognostic factors for IHR-free survival in both univariate and multivariate analyses. TERT overexpression was the only significant prognostic factor for late IHR in HCC treated with curative resection. And, the statistical significance of TERT overexpression on late IHR was limited to HBsAg-positive patients.

TERT promoter status and gene copy number gains: effect on TERT expression and association with prognosis in breast cancer

Upregulation of the telomerase reverse transcriptase (TERT) gene in human cancers leads to telomerase activation, which contributes to the growth advantage and survival of tumor cells. Molecular mechanisms of TERT upregulation are complex, tumor-specific and can be clinically relevant. To investigate these mechanisms in breast cancer, we sequenced the TERT promoter, evaluated TERT copy number changes and assessed the expression of the MYC oncogene, a known transcriptional TERT regulator, in two breast cancer cohorts comprising a total of 122 patients. No activating TERT promoter mutations were found, suggesting that this mutational mechanism is not likely to be involved in TERT upregulation in breast cancer. The T349C promoter polymorphism found in up to 50% of cases was not correlated with TERT expression, but T349C carriers had significantly shorter disease-free survival. TERT gains (15-25% of cases) were strongly correlated with increased TERT mRNA expression and worse patient prognosis in terms of disease-free and overall survival. Particularly aggressive breast cancers were characterized by an association of TERT gains with MYC overexpression. These results evidence a significant effect of gene copy number gain on the level of TERT expression and provide a new insight into the clinical significance of TERT and MYC upregulation in breast cancer.

Associations of TERT polymorphisms with hepatocellular carcinoma risk in a Han Chinese population

Genetic association analysis and functional analysis have suggested that telomerase reverse transcriptase (TERT) gene affects the predisposition to various tumors. In this study, we wanted to explore the association between TERT variants and hepatocellular carcinoma (HCC) risk in a Han Chinese population via a case-control study of 473 HCC patients and 564 controls. Sequenom Mass-ARRAY platform was applied to determine the genotype of TERT polymorphisms in these subjects. Odds ratios and 95% confidence intervals that calculated by logistic regression analysis were used to assess the association under the genotype, dominant, recessive, and additive models. The "AA" genotype frequency of TERT rs2242652 in cases was significantly lower than in controls (1.69% versus 3.72%). We found two SNPs were associated with decreased risk of HCC with or without the adjustment for age and gender: rs10069690 under an additive model (adjusted OR = 0.77, 95% CI: 0.60-0.98, P = 0.038); rs2242652 under a dominant model (adjusted OR = 0.72, 95% CI: 0.54-0.95, P = 0.022) and an additive model (adjusted OR = 0.72, 95% CI: 0.56-0.92, P = 0.009). To our knowledge, the present study is the first to show the significant association between TERT polymorphisms and HCC susceptibility in a Han Chinese population from China, which may act as a potential prognostic biomarker in HCC patients.

Functional dissection of breast cancer risk-associated TERT promoter variants

The multi-cancer susceptibility locus at 5p15.33 includes TERT, encoding the telomerase catalytic subunit. Genome-wide association studies (GWAS) have identified six single nucleotide polymorphisms (SNPs) in the TERT promoter associated with decreased breast cancer risk, although the precise causal variants and their mechanisms of action have remained elusive. Luciferase reporter assays indicated that the protective haplotype reduced TERT promoter activity in human mammary epithelial and cancer cells in an estrogen-independent manner. Using single variant constructs, we identified rs3215401 and rs2853669 as likely functional variants. Silencing of MYC decreased TERT promoter activity but neither MYC nor ETS2 silencing conferred allele-specificity. In chromatin immunoprecipitation experiments, the ETS protein GABPA, but not ETS2 or ELF1, bound rs2853669 in an allele-specific manner in mammary epithelial cells. Investigation of open chromatin in mammoplasty samples suggested involvement of three additional variants, though not rs3215401 or rs2853669. Chromosome conformation capture revealed no interaction of the TERT promoter with regulatory elements in the locus, indicating limited local impact of candidate variants on the TERT promoter. Collectively, our functional studies of the TERT-CLPTM1L breast cancer susceptibility locus describe rs2853669 as a functional variant of this association signal among three other potentially causal variants and demonstrate the versatile mechanisms by which TERT promoter variants may affect breast cancer 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 of a novel genetic variant in RP11-650L12.2 with risk of colorectal cancer in Han Chinese population

BACKGROUND

This study aimed to investigate the associations of selected polymorphisms in RP11-650L12.2 with the risk of colorectal cancer (CRC) in a Chinese population.

METHODS

A total of 821 CRC cases (test set: 320, validation set: 501) and 857 healthy controls (test set: 319, validation set: 538) were enrolled in this study. Demographic characteristics and lifestyle information were collected by a validated questionnaire. A sample of 5ml venous blood was collected from each subject for DNA isolation, and the selected polymorphisms (rs144182521, rs514743, rs76071148, rs149941240) were genotyped by MassArray technique.

RESULTS

The rs149941240 polymorphism was significantly associated with the risk of CRC, with ORs of 1.50 (95% CI: 1.15-1.96) by co-dominant model and 1.45 (95% CI: 1.21-1.87) by dominant model in the test set, respectively. Correspondingly, the ORs were 1.48 (95% CI: 1.19-1.82) and 1.41 (95% CI: 1.15-1.73) in the validation set, respectively. The crossover analysis showed that non-smokers with the variant genotypes in rs149941240 had a significantly increased risk of CRC than those with wild genotype by dominant model in the validation set (OR 1.42, 95% CI 1.04-1.96). However, no gene-environment multiplicative interactions of rs149941240 with tobacco smoking were found on risk of CRC.

CONCLUSIONS

Our findings suggest that rs149941240 polymorphism was associated with the risk of CRC, and might contribute to the susceptibility to CRC. The effects of this polymorphism should be validated in a larger sample and require further mechanistic investigations to determine the nature of its influence on CRC.

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.

Clinicopathological characteristics of TERT promoter mutation and telomere length in hepatocellular carcinoma

Promoter mutations in telomerase reverse transcriptase (TERT) and telomere length have been studied in various tumors. In the present study, the frequency and clinical characteristics of TERT promoter mutation and telomere length were studied in hepatocellular carcinoma (HCC). TERT promoter mutation and telomere length were analyzed in 162 tumor samples of the patients with HCC by sequencing and real-time PCR, respectively. The TERT promoter mutation rate was 28.8% (46/160) in HCC and was associated with males (P = 0.027). The telomere length was not significantly different in the presence of a TERT promoter mutation but was shorter in high-grade tumor stages (P = 0.048). Survival analyses showed that poor overall survival was associated with longer telomere length (P = 0.013). However, the TERT promoter mutation did not have a prognostic value for HCC. Multivariate survival analyses demonstrated that the telomere length was an independent prognostic marker for poor overall survival (hazard ratio = 1.75, 95% confidence interval: 1.046-2.913, P = 0.033). These data demonstrated that TERT promoter mutation is a frequent event in HCC; however, telomere length, but not the presence of a TERT promoter mutation, might have potential value as a prognostic indicator of HCC.

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.

Human Specific Regulation of the Telomerase Reverse Transcriptase Gene

Telomerase, regulated primarily by the transcription of its catalytic subunit telomerase reverse transcriptase (TERT), is critical for controlling cell proliferation and tissue homeostasis by maintaining telomere length. Although there is a high conservation between human and mouse TERT genes, the regulation of their transcription is significantly different in these two species. Whereas mTERT expression is widely detected in adult mice, hTERT is expressed at extremely low levels in most adult human tissues and cells. As a result, mice do not exhibit telomere-mediated replicative aging, but telomere shortening is a critical factor of human aging and its stabilization is essential for cancer development in humans. The chromatin environment and epigenetic modifications of the hTERT locus, the binding of transcriptional factors to its promoter, and recruitment of nucleosome modifying complexes all play essential roles in restricting its transcription in different cell types. In this review, we will discuss recent progress in understanding the molecular mechanisms of TERT regulation in human and mouse tissues and cells, and during cancer development.