Telomerase Promoter Mutations Research Articles

Using deep learning to decipher the impact of telomerase promoter mutations on the dynamic metastatic morpholome.

Melanoma showcases a complex interplay of genetic alterations and intra- and inter-cellular morphological changes during metastatic transformation. While pivotal, the role of specific mutations in dictating these changes still needs to be fully elucidated. Telomerase promoter mutations (TERTp mutations) significantly influence melanoma's progression, invasiveness, and resistance to various emerging treatments, including chemical inhibitors, telomerase inhibitors, targeted therapy, and immunotherapies. We aim to understand the morphological and phenotypic implications of the two dominant monoallelic TERTp mutations, C228T and C250T, enriched in melanoma metastasis. We developed isogenic clonal cell lines containing the TERTp mutations and utilized dual-color expression reporters steered by the endogenous Telomerase promoter, giving us allelic resolution. This approach allowed us to monitor morpholomic variations induced by these mutations. TERTp mutation-bearing cells exhibited significant morpholome differences from their wild-type counterparts, with increased allele expression patterns, augmented wound-healing rates, and unique spatiotemporal dynamics. Notably, the C250T mutation exerted more pronounced changes in the morpholome than C228T, suggesting a differential role in metastatic potential. Our findings underscore the distinct influence of TERTp mutations on melanoma's cellular architecture and behavior. The C250T mutation may offer a unique morpholomic and systems-driven advantage for metastasis. These insights provide a foundational understanding of how a non-coding mutation in melanoma metastasis affects the system, manifesting in cellular morpholome.

Recent in vitro models and tissue engineering strategies to study glioblastoma

Glioblastoma is a highly malignant brain tumor classified as grade IV with a poor prognosis and approximately a year of survival rate. The molecular changes that trigger primary glioblastoma are usually epidermal growth factor receptor mutations and amplifications, Mouse Double Minute and TP53 mutations, p16 deletion, phosphatase and tensin homolog and telomerase promoter mutations. In the vast majority of glioblastomas, altered signaling pathways were identified as receptor tyrosine kinase/Ras/PI3K, p53. Isocitrate dehydrogenase 1/2 mutations have also been associated with poor prognosis in glioblastoma The treatment options are very limited and complicated because of the diverse composition and heterogeneity of the tumors and unresponsiveness to the treatments with the existence of barriers reaching the brain tissue. Despite new trials, drug candidates that appeared effective in cell culture or mouse models failed in the clinic. Recently, new sophisticated experimental systems, including the those that mimic the tumor microenvironment, have started being used by several research groups, which will allow accurate prediction of drug efficacy. Tissue engineering strategies are also being combined with innovative cancer models, including spheroids, tumorspheres, organotypic slices, explants, tumoroids, and organoids. Such 3D systems provide powerful tools for studying glioblastoma biology by representing the dynamic evolution of the disease from the early to the metastatic stages and enabling interaction with the microenvironment. In this review, we both enlighten the molecular mechanisms that lead to glioblastoma development and detailed information on the tissue engineering approaches that have been used to model glioblastoma and the tumor microenvironment with the advantages and disadvantages. We anticipate that these novel approaches could improve the reliability of preclinical data by reducing the need for animal models.

Mesenchymal and MAPK Expression Signatures Associate with Telomerase Promoter Mutations in Multiple Cancers.

In a substantial fraction of cancers TERT promoter (TERTp) mutations drive expression of the catalytic subunit of telomerase, contributing to their proliferative immortality. We conducted a pan-cancer analysis of cell lines and find a TERTp mutation expression signature dominated by epithelial-to-mesenchymal transition and MAPK signaling. These data indicate that TERTp mutants are likely to generate distinctive tumor microenvironments and intercellular interactions. Analysis of high-throughput screening tests of 546 small molecules on cell line growth indicated that TERTp mutants displayed heightened sensitivity to specific drugs, including RAS pathway inhibitors, and we found that inhibition of MEK1 and 2, key RAS/MAPK pathway effectors, inhibited TERT mRNA expression. Consistent with an enrichment of mesenchymal states in TERTp mutants, cell lines and some patient tumors displayed low expression of the central adherens junction protein E-cadherin, and we provide evidence that its expression in these cells is regulated by MEK1/2. Several mesenchymal transcription factors displayed elevated expression in TERTp mutants including ZEB1 and 2, TWIST1 and 2, and SNAI1. Of note, the developmental transcription factor SNAI2/SLUG was conspicuously elevated in a significant majority of TERTp-mutant cell lines, and knock-down experiments suggest that it promotes TERT expression. IMPLICATIONS: Cancers harboring TERT promoter mutations are often more lethal, but the basis for this higher mortality remains unknown. Our study identifies that TERTp mutants, as a class, associate with a distinct gene and protein expression signature likely to impact their biological and clinical behavior and provide new directions for investigating treatment approaches for these cancers.

Induction of Telomere Dysfunction Prolongs Disease Control of Therapy-Resistant Melanoma.

Purpose: Telomerase promoter mutations are highly prevalent in human tumors including melanoma. A subset of patients with metastatic melanoma often fail multiple therapies, and there is an unmet and urgent need to prolong disease control for those patients.Experimental Design: Numerous preclinical therapy-resistant models of human and mouse melanoma were used to test the efficacy of a telomerase-directed nucleoside, 6-thio-2'-deoxyguanosine (6-thio-dG). Integrated transcriptomics and proteomics approaches were used to identify genes and proteins that were significantly downregulated by 6-thio-dG.Results: We demonstrated the superior efficacy of 6-thio-dG both in vitro and in vivo that results in telomere dysfunction, leading to apoptosis and cell death in various preclinical models of therapy-resistant melanoma cells. 6-thio-dG concomitantly induces telomere dysfunction and inhibits the expression level of AXL.Conclusions: In summary, this study shows that indirectly targeting aberrant telomerase in melanoma cells with 6-thio-dG is a viable therapeutic approach in prolonging disease control and overcoming therapy resistance. Clin Cancer Res; 24(19); 4771-84. ©2018 AACR See related commentary by Teh and Aplin, p. 4629.

Telomerase promoter mutations and copy number alterations in solitary fibrous tumours

AimsSolitary fibrous tumour (SFT) is an infrequently metastasising mesenchymal tumour defined by the NAB2–STAT6 fusion gene. Activating mutations in the telomerase reverse transcriptase (hTERT) gene promoter has been reported to...

Telomerase promoter mutations in human immunodeficiency virus-related conjunctiva neoplasia

BackgroundSquamous cell carcinoma (SCC) of the conjunctiva is a common cancer in Africa mainly associated with solar ultraviolet (UV) exposure and human immunodeficiency virus (HIV) infection. We analyzed the role of HIV on the occurrence of telomerase reverse transcriptase (TERT) promoter mutations among a cohort of conjunctiva neoplasia Ugandan patients.MethodsTelomerase reverse transcriptase promoter mutations were searched in 72 conjunctiva neoplasia cases, comprising SCC and intraepithelial neoplasia grade 1–3 (CIN1–3), as well as in 53 conjunctiva normal tissues and in 24 HIV-related Kaposi sarcoma.ResultsThe average prevalence of TERT promoter mutations in conjunctiva neoplasia was 31.9%. The mutation rates were significantly higher in HIV-positive (31.8% of CIN1 and CIN2, 46.2% of CIN3 and SCC,) than HIV-negative patients (22.2% of CIN1 and CIN2, 13.3% of CIN3 and SCC). Such mutations were rarely identified among HIV-positive conjunctiva controls (3.6%) and never in Kaposi sarcoma lesions. The most frequent variations were the hot spots − 124G>A and − 146G>A and tandem transitions − 124_125GG>AA and − 138_139GG>AA.ConclusionsTelomerase reverse transcriptase promoter mutations are early events in conjunctival neoplasia and could be used for timely diagnosis of conjunctiva tumours. The high frequency of UV-signatures in HIV-positive conjunctiva lesions suggests an additive effect of the virus to UV-related mutagenesis.

Use of telomerase promoter mutations to mark specific molecular subsets with reciprocal clinical behavior in IDH mutant and IDH wild-type diffuse gliomas.

OBJECTIVE Recent studies have established that hemispheric diffuse gliomas may be grouped into subsets on the basis of molecular markers; these subsets are loosely correlated with the histopathological diagnosis but are strong predictors of clinical tumor behavior. Based on an analysis of molecular and clinical parameters, the authors hypothesized that mutations of the telomerase promoter (TERTp-mut) mark separate oncogenic programs among isocitrate dehydrogenase 1 and/or 2 (IDH) mutant (IDH-mut) and IDH wild-type (IDH-wt) diffuse gliomas independent of histopathology or WHO grade. METHODS Four molecular subsets of the combined statuses of IDH and TERT-promoter mutations (double mutant, IDH only, TERT only, and double negative) were defined. Differences in age, anatomical location, molecular genetics, and survival rates in a surgical cohort of 299 patients with a total of 356 hemispheric diffuse gliomas (WHO Grade II, III, or IV) were analyzed. RESULTS TERTp-mut were present in 38.8% of IDH-mut and 70.2% of IDH-wt gliomas. The mutational status was stable in each patient at 57 recurrence events over a 2645-month cumulative follow-up period. Among patients with IDH-mut gliomas, those in the double-mutant subset had better survival and a lower incidence of malignant degeneration than those in the IDH-only subset. Of patients in the double-mutant subset, 96.3% were also positive for 1p/19q codeletions. All patients with 1p/19q codeletions had TERTp-mut. In patients with IDH-mut glioma, epidermal growth factor receptor or phosphatase and tensin homolog mutations were not observed, and copy-number variations were uncommon. Among IDH-wt gliomas, the TERT-only subset was associated with significantly higher age, higher Ki-67 labeling index, primary glioblastoma-specific oncogenic changes, and poor survival. The double-negative subset was genetically and biologically heterogeneous. Survival analyses (Kaplan-Meier, multivariate, and regression-tree analyses) confirmed that patients in the 4 molecular subsets had distinct prognoses. CONCLUSIONS Molecular subsets result in different tumor biology and clinical behaviors in hemispheric diffuse gliomas.

Telomerase promoter mutations in cancer: beyond immortalization?

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Telomerase promoter mutations in cancer: an emerging molecular biomarker?

Cell immortalization has been considered for a long time as a classic hallmark of cancer cells. Besides telomerase reactivation, such immortalization could be due to telomere maintenance through the "alternative mechanism of telomere lengthening" (ALT) but the mechanisms underlying both forms of reactivation remained elusive. Mutations in the coding region of telomerase gene are very rare in the cancer setting, despite being associated with some degenerative diseases. Recently, mutations in telomerase (TERT) gene promoter were found in sporadic and familial melanoma and subsequently in several cancer models, notably in gliomas, thyroid cancer and bladder cancer. The importance of these findings has been reinforced by the association of TERT mutations in some cancer types with tumour aggressiveness and patient survival. In the first part of this review, we summarize the data on the biology of telomeres and telomerase, available methodological approaches and non-neoplastic diseases associated with telomere dysfunction. In the second part, we review the information on telomerase expression and genetic alterations in the most relevant types of cancer (skin, thyroid, bladder and central nervous system) on record, and discuss the value of telomerase as a new biomarker with impact on the prognosis and survival of the patients and as a putative therapeutic target.

TERT Promoter Mutations Are a Major Indicator of Poor Outcome in Differentiated Thyroid Carcinomas

Context:Telomerase promoter mutations (TERT) were recently described in follicular cell-derived thyroid carcinomas (FCDTC) and seem to be more prevalent in aggressive cancers.Objectives:We aimed to evaluate the frequency of TERT promoter mutations in thyroid lesions and to investigate the prognostic significance of such mutations in a large cohort of patients with differentiated thyroid carcinomas (DTCs).Design:This was a retrospective observational study.Setting and Patients:We studied 647 tumors and tumor-like lesions. A total of 469 patients with FCDTC treated and followed in five university hospitals were included. Mean follow-up (±SD) was 7.8 ± 5.8 years.Main Outcome Measures:Predictive value of TERT promoter mutations for distant metastasization, disease persistence at the end of follow-up, and disease-specific mortality.Results:TERT promoter mutations were found in 7.5% of papillary carcinomas (PTCs), 17.1% of follicular carcinomas, 29.0% of poorly differentiated carcinomas, and 33.3% of anaplastic thyroid carcinomas. Patients with TERT-mutated tumors were older (P < .001) and had larger tumors (P = .002). In DTCs, TERT promoter mutations were significantly associated with distant metastases (P < .001) and higher stage (P < .001). Patients with DTC harboring TERT promoter mutations were submitted to more radioiodine treatments (P = .009) with higher cumulative dose (P = .004) and to more treatment modalities (P = .001). At the end of follow-up, patients with TERT-mutated DTCs were more prone to have persistent disease (P = .001). TERT promoter mutations were significantly associated with disease-specific mortality [in the whole FCDTC (P < .001)] in DTCs (P < .001), PTCs (P = .001), and follicular carcinomas (P < .001). After adjusting for age at diagnosis and gender, the hazard ratio was 10.35 (95% confidence interval 2.01–53.24; P = .005) in DTC and 23.81 (95% confidence interval 1.36–415.76; P = .03) in PTCs.Conclusions:TERT promoter mutations are an indicator of clinically aggressive tumors, being correlated with worse outcome and disease-specific mortality in DTC. TERT promoter mutations have an independent prognostic value in DTC and, notably, in PTC.