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Sang Y, Hu G, Xue J, Chen M, Hong S, Liu R. Risk stratification by combining common genetic mutations and TERT promoter methylation in papillary thyroid cancer. Endocrine 2024:10.1007/s12020-024-03722-6. [PMID: 38356100 DOI: 10.1007/s12020-024-03722-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Accepted: 01/30/2024] [Indexed: 02/16/2024]
Abstract
PURPOSE Risk stratification based on somatic mutations in TERT promoter and BRAF/RAS has been well established for papillary thyroid cancer (PTC), and there is emerging evidence showed that TERT promoter methylation was frequently observed in thyroid cancer patients with adverse features. This study was aimed to comprehensive explore the prognostic value of BRAF/RAS mutations, TERT promoter mutations, and TERT promoter methylation in PTC. METHODS The relationships of BRAF/RAS mutations, TERT promoter mutations, and TERT promoter methylation with clinical characteristics and outcomes of PTC were analyzed in 382 patients with PTC. RESULTS TERT promoter mutation and hypermethylation were collectively observed in 52 (13.6%) samples and associated with BRAF/RAS mutation, aggressive clinical characteristics, and poor clinical outcomes of PTC. Coexistence of BRAF/RAS and TERT alterations was found in 45 of 382 (11.8%) PTC patients and strongly associated with old patient age, extrathyroidal extension, advanced pathologic T stage and metastasis. Importantly, patients with both BRAF/RAS and TERT alterations had higher rates of tumor recurrence (13.6% vs 1.5%, P = 0.042) and disease progression (24.4% vs 3.3%, P < 0.001) than patients without any alterations, and cox regression analysis revealed that the coexistence of BRAF/RAS and TERT alterations, but not BRAF/RAS or TERT alterations alone, increased the risk of progression-free interval with an adjusted HR of 10.35 (95% CI: 1.79-59.81, P = 0.009). CONCLUSIONS This study suggested that comprehensively analysis of BRAF/RAS mutations, TERT promoter mutation and methylation is an effective strategy to identify high-risk patients with PTC.
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Affiliation(s)
- Ye Sang
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan Second Road, Guangzhou, China
| | - Guanghui Hu
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan Second Road, Guangzhou, China
| | - Junyu Xue
- Department of Endocrinology, The First Affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan Second Road, Guangzhou, China
| | - Mengke Chen
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan Second Road, Guangzhou, China
| | - Shubin Hong
- Department of Endocrinology, The First Affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan Second Road, Guangzhou, China
| | - Rengyun Liu
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan Second Road, Guangzhou, China.
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Li S, Xue J, Jiang K, Chen Y, Zhu L, Liu R. TERT promoter methylation is associated with high expression of TERT and poor prognosis in papillary thyroid cancer. Front Oncol 2024; 14:1325345. [PMID: 38313800 PMCID: PMC10834694 DOI: 10.3389/fonc.2024.1325345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Accepted: 01/04/2024] [Indexed: 02/06/2024] Open
Abstract
The telomerase reverse transcriptase (TERT) is overexpressed and associated with poor prognosis in papillary thyroid cancer (PTC), the most common subtype of thyroid cancer. The overexpression of TERT in PTC was partially attributed to transcriptional activation by two hotspot mutations in the core promoter region of this gene. As one of the major epigenetic mechanisms of gene expression regulation, DNA methylation has been proved to regulate several tumor-related genes in PTC. However, the association of TERT promoter DNA methylation with TERT expression and PTC progression is still unclear. By treating PTC cell lines with demethylating agent decitabine, we found that the TERT promoter methylation and the genes' expression were remarkably decreased. Consistently, PTC patients with TERT hypermethylation had significantly higher TERT expression than patients with TERT hypomethylation. Moreover, TERT hypermethylated patients showed significant higher rates of poor clinical outcomes than patients with TERT hypomethylation. Results from the cox regression analysis showed that the hazard ratios (HRs) of TERT hypermethylation for overall survival, disease-specific survival, disease-free interval (DFI) and progression-free interval (PFI) were 4.81 (95% CI, 1.61-14.41), 8.28 (95% CI, 2.14-32.13), 3.56 (95% CI, 1.24-10.17) and 3.32 (95% CI, 1.64-6.71), respectively. The HRs for DFI and PFI remained significant after adjustment for clinical risk factors. These data suggest that promoter DNA methylation upregulates TERT expression and associates with poor clinical outcomes of PTC, thus holds the potential to be a valuable prognostic marker for PTC risk stratification.
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Affiliation(s)
- Shiyong Li
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Junyu Xue
- Department of Endocrinology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Ke Jiang
- Department of Head and Neck Surgery, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Yulu Chen
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Lefan Zhu
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Rengyun Liu
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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Tornesello ML, Cerasuolo A, Starita N, Amiranda S, Bonelli P, Tuccillo FM, Buonaguro FM, Buonaguro L, Tornesello AL. Reactivation of telomerase reverse transcriptase expression in cancer: the role of TERT promoter mutations. Front Cell Dev Biol 2023; 11:1286683. [PMID: 38033865 PMCID: PMC10684755 DOI: 10.3389/fcell.2023.1286683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/02/2023] [Indexed: 12/02/2023] Open
Abstract
Telomerase activity and telomere elongation are essential conditions for the unlimited proliferation of neoplastic cells. Point mutations in the core promoter region of the telomerase reverse transcriptase (TERT) gene have been found to occur at high frequencies in several tumour types and considered a primary cause of telomerase reactivation in cancer cells. These mutations promote TERT gene expression by multiple mechanisms, including the generation of novel binding sites for nuclear transcription factors, displacement of negative regulators from DNA G-quadruplexes, recruitment of epigenetic activators and disruption of long-range interactions between TERT locus and telomeres. Furthermore, TERT promoter mutations cooperate with TPP1 promoter nucleotide changes to lengthen telomeres and with mutated BRAF and FGFR3 oncoproteins to enhance oncogenic signalling in cancer cells. TERT promoter mutations have been recognized as an early marker of tumour development or a major indicator of poor outcome and reduced patients survival in several cancer types. In this review, we summarize recent findings on the role of TERT promoter mutations, telomerase expression and telomeres elongation in cancer development, their clinical significance and therapeutic opportunities.
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Affiliation(s)
- Maria Lina Tornesello
- Molecular Biology and Viral Oncology Unit, Istituto Nazionale Tumori IRCCS Fondazione G. Pascale, Napoli, Italy
| | - Andrea Cerasuolo
- Molecular Biology and Viral Oncology Unit, Istituto Nazionale Tumori IRCCS Fondazione G. Pascale, Napoli, Italy
| | - Noemy Starita
- Molecular Biology and Viral Oncology Unit, Istituto Nazionale Tumori IRCCS Fondazione G. Pascale, Napoli, Italy
| | - Sara Amiranda
- Molecular Biology and Viral Oncology Unit, Istituto Nazionale Tumori IRCCS Fondazione G. Pascale, Napoli, Italy
| | - Patrizia Bonelli
- Molecular Biology and Viral Oncology Unit, Istituto Nazionale Tumori IRCCS Fondazione G. Pascale, Napoli, Italy
| | - Franca Maria Tuccillo
- Molecular Biology and Viral Oncology Unit, Istituto Nazionale Tumori IRCCS Fondazione G. Pascale, Napoli, Italy
| | - Franco M. Buonaguro
- Molecular Biology and Viral Oncology Unit, Istituto Nazionale Tumori IRCCS Fondazione G. Pascale, Napoli, Italy
| | - Luigi Buonaguro
- Innovative Immunological Models Unit, Istituto Nazionale Tumori IRCCS Fondazione G. Pascale, Napoli, Italy
| | - Anna Lucia Tornesello
- Innovative Immunological Models Unit, Istituto Nazionale Tumori IRCCS Fondazione G. Pascale, Napoli, Italy
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4
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Landa I, Thornton CE, Xu B, Haase J, Krishnamoorthy GP, Hao J, Knauf JA, Herbert ZT, Martínez P, Blasco MA, Ghossein R, Fagin JA. Telomerase Upregulation Induces Progression of Mouse BrafV600E-Driven Thyroid Cancers and Triggers Nontelomeric Effects. Mol Cancer Res 2023; 21:1163-1175. [PMID: 37478162 PMCID: PMC11193891 DOI: 10.1158/1541-7786.mcr-23-0144] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/15/2023] [Accepted: 07/18/2023] [Indexed: 07/23/2023]
Abstract
Mutations in the promoter of the telomerase reverse transcriptase (TERT) gene are the paradigm of a cross-cancer alteration in a noncoding region. TERT promoter mutations (TPM) are biomarkers of poor prognosis in cancer, including thyroid tumors. TPMs enhance TERT transcription, which is otherwise silenced in adult tissues, thus reactivating a bona fide oncoprotein. To study TERT deregulation and its downstream consequences, we generated a Tert mutant promoter mouse model via CRISPR/Cas9 engineering of the murine equivalent locus (Tert-123C>T) and crossed it with thyroid-specific BrafV600E-mutant mice. We also employed an alternative model of Tert overexpression (K5-Tert). Whereas all BrafV600E animals developed well-differentiated papillary thyroid tumors, 29% and 36% of BrafV600E+Tert-123C>T and BrafV600E+K5-Tert mice progressed to poorly differentiated cancers at week 20, respectively. Tert-upregulated tumors showed increased mitosis and necrosis in areas of solid growth, and older animals displayed anaplastic-like features, that is, spindle cells and macrophage infiltration. Murine TPM increased Tert transcription in vitro and in vivo, but temporal and intratumoral heterogeneity was observed. RNA-sequencing of thyroid tumor cells showed that processes other than the canonical Tert-mediated telomere maintenance role operate in these specimens. Pathway analysis showed that MAPK and PI3K/AKT signaling, as well as processes not previously associated with this tumor etiology, involving cytokine, and chemokine signaling, were overactivated. These models constitute useful preclinical tools to understand the cell-autonomous and microenvironment-related consequences of Tert-mediated progression in advanced thyroid cancers and other aggressive tumors carrying TPMs. IMPLICATIONS Telomerase-driven cancer progression activates pathways that can be dissected and perhaps therapeutically exploited.
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Affiliation(s)
- Iñigo Landa
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Caitlin E.M. Thornton
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Bin Xu
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Jacob Haase
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Gnana P. Krishnamoorthy
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Jingzhu Hao
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | | | - Zachary T. Herbert
- Molecular Biology Core Facilities, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Paula Martínez
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - María A. Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - Ronald Ghossein
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - James A. Fagin
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
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5
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Fagin JA, Krishnamoorthy GP, Landa I. Pathogenesis of cancers derived from thyroid follicular cells. Nat Rev Cancer 2023; 23:631-650. [PMID: 37438605 PMCID: PMC10763075 DOI: 10.1038/s41568-023-00598-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/08/2023] [Indexed: 07/14/2023]
Abstract
The genomic simplicity of differentiated cancers derived from thyroid follicular cells offers unique insights into how oncogenic drivers impact tumour phenotype. Essentially, the main oncoproteins in thyroid cancer activate nodes in the receptor tyrosine kinase-RAS-BRAF pathway, which constitutively induces MAPK signalling to varying degrees consistent with their specific biochemical mechanisms of action. The magnitude of the flux through the MAPK signalling pathway determines key elements of thyroid cancer biology, including differentiation state, invasive properties and the cellular composition of the tumour microenvironment. Progression of disease results from genomic lesions that drive immortalization, disrupt chromatin accessibility and cause cell cycle checkpoint dysfunction, in conjunction with a tumour microenvironment characterized by progressive immunosuppression. This Review charts the genomic trajectories of these common endocrine tumours, while connecting them to the biological states that they confer.
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Affiliation(s)
- James A Fagin
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - Gnana P Krishnamoorthy
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Iñigo Landa
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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6
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Landa I. InTERTwined: how TERT promoter mutations impact BRAF V600E-driven thyroid cancers. CURRENT OPINION IN ENDOCRINE AND METABOLIC RESEARCH 2023; 30:100460. [PMID: 37576936 PMCID: PMC10419322 DOI: 10.1016/j.coemr.2023.100460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Thyroid cancers are often initiated by the acquisition of a BRAFV600E mutation. BRAFV600E-driven thyroid tumors display a wide range of behaviors, from the slow-growing papillary carcinomas to the highly aggressive anaplastic. Mutations in the promoter of TERT (telomerase reverse transcriptase) gene were discovered a decade ago and identified as prevalent events in thyroid cancers. Multiple studies showed that TERT promoter mutations, particularly when co-occurring with BRAFV600E, are markers of poor prognosis across thyroid cancer subtypes, and can be implemented for routine clinical stratification. Mechanistically, TERT promoter mutations reactivate telomerase expression via the differential recruitment of transcriptional complexes. Re-expression of TERT impacts tumor biology, plausibly via both the well-known function of telomerase maintaining telomeres and by affecting other cancer-relevant processes.
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Affiliation(s)
- Iñigo Landa
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
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7
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Wei Y, Han S, Wen J, Liao J, Liang J, Yu J, Chen X, Xiang S, Huang Z, Zhang B. E26 transformation-specific transcription variant 5 in development and cancer: modification, regulation and function. J Biomed Sci 2023; 30:17. [PMID: 36872348 PMCID: PMC9987099 DOI: 10.1186/s12929-023-00909-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 02/27/2023] [Indexed: 03/07/2023] Open
Abstract
E26 transformation-specific (ETS) transcription variant 5 (ETV5), also known as ETS-related molecule (ERM), exerts versatile functions in normal physiological processes, including branching morphogenesis, neural system development, fertility, embryonic development, immune regulation, and cell metabolism. In addition, ETV5 is repeatedly found to be overexpressed in multiple malignant tumors, where it is involved in cancer progression as an oncogenic transcription factor. Its roles in cancer metastasis, proliferation, oxidative stress response and drug resistance indicate that it is a potential prognostic biomarker, as well as a therapeutic target for cancer treatment. Post-translational modifications, gene fusion events, sophisticated cellular signaling crosstalk and non-coding RNAs contribute to the dysregulation and abnormal activities of ETV5. However, few studies to date systematically summarized the role and molecular mechanisms of ETV5 in benign diseases and in oncogenic progression. In this review, we specify the molecular structure and post-translational modifications of ETV5. In addition, its critical roles in benign and malignant diseases are summarized to draw a panorama for specialists and clinicians. The updated molecular mechanisms of ETV5 in cancer biology and tumor progression are delineated. Finally, we prospect the further direction of ETV5 research in oncology and its potential translational applications in the clinic.
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Affiliation(s)
- Yi Wei
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shenqi Han
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jingyuan Wen
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jingyu Liao
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Junnan Liang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jingjing Yu
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoping Chen
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Key Laboratory of Organ Transplantation, Ministry of Education, Wuhan, China
- Key Laboratory of Organ Transplantation, National Health Commission, Wuhan, China
- Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, China
| | - Shuai Xiang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China.
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Zhao Huang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China.
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Bixiang Zhang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
- Clinical Medical Research Center of Hepatic Surgery at Hubei Province, Wuhan, China.
- Hubei Key Laboratory of Hepato-Pancreatic-Biliary Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
- Key Laboratory of Organ Transplantation, Ministry of Education, Wuhan, China.
- Key Laboratory of Organ Transplantation, National Health Commission, Wuhan, China.
- Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, China.
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Landa I, Thornton CEM, Xu B, Haase J, Krishnamoorthy GP, Hao J, Knauf JA, Herbert ZT, Blasco MA, Ghossein R, Fagin JA. Telomerase reactivation induces progression of mouse Braf V600E -driven thyroid cancers without telomere lengthening. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.24.525280. [PMID: 36747657 PMCID: PMC9900760 DOI: 10.1101/2023.01.24.525280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Mutations in the promoter of the telomerase reverse transcriptase ( TERT ) gene are the paradigm of a cross-cancer alteration in a non-coding region. TERT promoter mutations (TPMs) are biomarkers of poor prognosis in several tumors, including thyroid cancers. TPMs enhance TERT transcription, which is otherwise silenced in adult tissues, thus reactivating a bona fide oncoprotein. To study TERT deregulation and its downstream consequences, we generated a Tert mutant promoter mouse model via CRISPR/Cas9 engineering of the murine equivalent locus (Tert -123C>T ) and crossed it with thyroid-specific Braf V600E -mutant mice. We also employed an alternative model of Tert overexpression (K5-Tert). Whereas all Braf V600E animals developed well-differentiated papillary thyroid tumors, 29% and 36% of Braf V600E +Tert -123C>T and Braf V600E +K5-Tert mice progressed to poorly differentiated thyroid cancers at week 20, respectively. Braf+Tert tumors showed increased mitosis and necrosis in areas of solid growth, and older animals from these cohorts displayed anaplastic-like features, i.e., spindle cells and macrophage infiltration. Murine Tert promoter mutation increased Tert transcription in vitro and in vivo , but temporal and intra-tumoral heterogeneity was observed. RNA-sequencing of thyroid tumor cells showed that processes other than the canonical Tert-mediated telomere maintenance role operate in these specimens. Pathway analysis showed that MAPK and PI3K/AKT signaling, as well as processes not previously associated with this tumor etiology, involving cytokine and chemokine signaling, were overactivated. Braf+Tert animals remained responsive to MAPK pathway inhibitors. These models constitute useful pre-clinical tools to understand the cell-autonomous and microenvironment-related consequences of Tert-mediated progression in advanced thyroid cancers and other aggressive tumors carrying TPMs.
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Affiliation(s)
- Iñigo Landa
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Caitlin EM Thornton
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Bin Xu
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jacob Haase
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Gnana P. Krishnamoorthy
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jingzhu Hao
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Jeffrey A Knauf
- Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Zachary T Herbert
- Molecular Biology Core Facilities, Dana-Farber Cancer Institute, Boston, MA, USA
| | - María A Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - Ronald Ghossein
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - James A Fagin
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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9
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Shen X, Zhou C, Feng H, Li J, Xia T, Cheng X, Zhao R, Zou D. ETV1 Positively Correlated With Immune Infiltration and Poor Clinical Prognosis in Colorectal Cancer. Front Immunol 2022; 13:939806. [PMID: 35860243 PMCID: PMC9291282 DOI: 10.3389/fimmu.2022.939806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 06/03/2022] [Indexed: 11/13/2022] Open
Abstract
ObjectiveNumerous studies recently suggested that the immune microenvironment could influence the development of colorectal cancer (CRC). These findings implied that the infiltration of immune cells could be a promising prognostic biomarker for CRC.MethodsFurthermore, the Oncomine database and R2 platform analysis were applied in our research to validate CRC clinical prognosis via expression levels of polyoma enhancer activator 3 (PEA3) members. We explored the correlation of ETV1, ETV4, and ETV5 with tumor-infiltrating immune cells (TIICs) in CRC tumor microenvironments via the Tumor Immune Estimation Resource (TIMER) and Gene Expression Profiling Interactive Analysis (GEPIA). Immunohistochemistry (IHC) was used to validate our CRC clinical data.ResultsOur findings indicated that the upregulation of PEA3 members including ETV1 and ETV5 was positively associated with poor prognosis in CRC patients. Meanwhile, ETV1 and ETV5 may play significant roles in the development progress of CRC. Furthermore, ETV1 tends to be associated with immune infiltration of CRC, especially with cancer-associated fibroblasts and M2 macrophages.ConclusionThese findings revealed that ETV1 and ETV5 played significant roles in the development of CRC. Moreover, ETV1 was significantly associated with the infiltration of cancer-associated fibroblasts and M2 macrophages in CRC. Targeting ETV1 can be a potential auspicious approach for CRC treatment.
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Affiliation(s)
- Xiaonan Shen
- Department of Gastroenterology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chunhua Zhou
- Department of Gastroenterology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Haoran Feng
- Shanghai Institute of Digestive Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jialu Li
- State Key Laboratory for Oncogenes and Related Genes, Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Tianxue Xia
- Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Xi Cheng
- Department of General Surgery, Shanghai Institute of Digestive Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- *Correspondence: Xi Cheng, ; Ren Zhao, ; Duowu Zou,
| | - Ren Zhao
- Department of General Surgery, Shanghai Institute of Digestive Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- *Correspondence: Xi Cheng, ; Ren Zhao, ; Duowu Zou,
| | - Duowu Zou
- Department of Gastroenterology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- *Correspondence: Xi Cheng, ; Ren Zhao, ; Duowu Zou,
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10
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Emerging mechanisms of telomerase reactivation in cancer. Trends Cancer 2022; 8:632-641. [PMID: 35568649 PMCID: PMC7614490 DOI: 10.1016/j.trecan.2022.03.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/24/2022] [Accepted: 03/28/2022] [Indexed: 12/17/2022]
Abstract
Mutations in the promoter of human telomerase reverse transcriptase (hTERT) result in hyperactivation of hTERT. Notably, all mutations are G>A transitions, frequently found in a wide range of cancer types, and causally associated with cancer progression. Initially, the mutations were understood to reactivate hTERT by generating novel E26 transformation-specific (ETS) binding sites. Recent work reveals the role of DNA secondary structure G-quadruplexes, telomere binding factor(s), and chromatin looping in hTERT regulation. Here, we discuss these emerging findings in relation to the clinically significant promoter mutations to provide a broader understanding of the context-dependent outcomes that result in hTERT activation in normal and pathogenic conditions.
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11
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Downregulation and Hypermethylation of GABPB1 Is Associated with Aggressive Thyroid Cancer Features. Cancers (Basel) 2022; 14:cancers14061385. [PMID: 35326537 PMCID: PMC8946831 DOI: 10.3390/cancers14061385] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 02/27/2022] [Accepted: 02/28/2022] [Indexed: 02/01/2023] Open
Abstract
Simple Summary Promoter mutations of the telomerase reverse transcriptase (TERT) gene have been suggested as an oncogenic event in various cancers, including thyroid cancer (TC). GABPB1 is reported to activate TERT gene expression and has been proposed as a cancer therapeutic target. The aim of this study is to explore the fate of TC cells after disruption of GABPB1 and its role in TC. We found that besides the reported oncogenic role of GABPB1 in activating TERT, it also has tumor-suppressive functions in TC. Therefore, targeting GABPB1 for cancer therapy should be cautious since it may counteract its tumor-suppressive functions. Abstract Promoter mutations of the telomerase reverse transcriptase (TERT) gene occur frequently in thyroid carcinoma (TC), including papillary (PTC) and anaplastic subtypes (ATC). Given that the ETS family transcription factors GABPA and GABPB1 activate the mutant TERT promoter and induce TERT expression for telomerase activation, GABPB1 has been proposed as a cancer therapeutic target to inhibit telomerase. Here, we sought to determine the role of GABPB1 in TC pathogenesis. In TC-derived cells carrying the mutated TERT promoter, GABPB1 knockdown led to diminished TERT expression but significantly increased invasive potentials in vitro and metastatic potential in a xenograft zebrafish model and altered expression of markers for epithelial-to-mesenchymal transition. GABPB1 expression was downregulated in aggressive TCs. Low GABPB1 expression correlated with its promoter hypermethylation, which in turn was also associated with shorter disease-free survival. Consistently, DNA methylation inhibitors enhanced GABPB1 expression, as observed upon reduced promoter methylation. Our results suggest that GABPB1 is required for TERT expression and telomerase activation, but itself serves as a tumor suppressor to inhibit TC progression. Furthermore, aberrant DNA methylation leads to GABPB1 silencing, thereby promoting TC aggressiveness. Thus, caution is needed if targeting GABPB1 for cancer therapy is considered.
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12
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Thornton CEM, Hao J, Tamarapu PP, Landa I. Multiple ETS Factors Participate in the Transcriptional Control of TERT Mutant Promoter in Thyroid Cancers. Cancers (Basel) 2022; 14:cancers14020357. [PMID: 35053525 PMCID: PMC8774187 DOI: 10.3390/cancers14020357] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/07/2022] [Accepted: 01/10/2022] [Indexed: 01/09/2023] Open
Abstract
Simple Summary Mutations in the promoter region of the telomerase reverse transcriptase (TERT) gene are enriched in patients with advanced thyroid tumors. Their consequence is the reactivation of TERT expression through mechanisms that involve specific transcription factors and other signaling inputs. Here, we show that, contrary to what it has been shown in other tumor types, multiple factors of the ETS family are able to control TERT transcription and they do so in both the presence and absence of promoter mutations. We also show that TERT expression is more dependent on the MAPK signaling pathway in thyroid cells without TERT promoter mutations. Our work points to an intricate, still not fully characterized, regulatory network of TERT transcription in thyroid tumors. We caution against the assumption of mechanisms identified in other cancer lineages being identical in TERT-mutant thyroid specimens. Abstract Hotspot mutations in the TERT (telomerase reverse transcriptase) gene are key determinants of thyroid cancer progression. TERT promoter mutations (TPM) create de novo consensus binding sites for the ETS (“E26 transformation specific”) family of transcription factors. In this study, we systematically knocked down each of the 20 ETS factors expressed in thyroid tumors and screened their effects on TERT expression in seven thyroid cancer cell lines with defined TPM status. We observed that, unlike in other TPM-carrying cancers such as glioblastomas, ETS factor GABPA does not unambiguously regulate transcription from the TERT mutant promoter in thyroid specimens. In fact, multiple members of the ETS family impact TERT expression, and they typically do so in a mutation-independent manner. In addition, we observe that partial inhibition of MAPK, a central pathway in thyroid cancer transformation, is more effective at suppressing TERT transcription in the absence of TPMs. Taken together, our results show a more complex scenario of TERT regulation in thyroid cancers compared with other lineages and suggest that compensatory mechanisms by ETS and other regulators likely exist and advocate for the need for a more comprehensive understanding of the mechanisms of TERT deregulation in thyroid tumors before eventually exploring TPM-specific therapeutic strategies.
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Affiliation(s)
- Caitlin E. M. Thornton
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA; (C.E.M.T.); (J.H.)
- Harvard Medical School, Boston, MA 02115, USA
| | - Jingzhu Hao
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA; (C.E.M.T.); (J.H.)
- Harvard Medical School, Boston, MA 02115, USA
| | - Prasanna P. Tamarapu
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA;
| | - Iñigo Landa
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA; (C.E.M.T.); (J.H.)
- Harvard Medical School, Boston, MA 02115, USA
- Correspondence: ; Tel.: +1-617-525-5153
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13
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Zhang L, Fu R, Liu P, Wang L, Liang W, Zou H, Jia W, Tao L. Biological and prognostic value of ETV5 in high-grade serous ovarian cancer. J Ovarian Res 2021; 14:149. [PMID: 34736492 PMCID: PMC8570011 DOI: 10.1186/s13048-021-00899-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/14/2021] [Indexed: 11/29/2022] Open
Abstract
Background ETS transcription factors are known to act as either positive or negative regulators of the expression of genes involved in various biological processes. It was reported that ETS variant transcription factor 5 (ETV5), a key member of the ETS family, mainly plays a role as an potential oncogene in various malignant tumors. However, the role and mechanism of ETV5 in high-grade serous ovarian cancer (HGSOC) have not been elucidated. Methods Quantitative real-time polymerase chain reaction (qRT-PCR) assay was used to detect ETV5 messenger ribonucleic acid (mRNA) expression in 87 HGSOC tissues and 35 normal fallopian tube tissues. Western blotting and qRT-PCR were used to detect the protein and mRNA expression of ETV5 in six ovarian cancer (OC) and human embryonic cell lines. Knockdown or overexpression of ETV5 in HGSOC cell lines, Cell Counting Kit-8, colony formation, and transwell assays were used to detect HGSOC cell proliferation, invasion, and migration capabilities. The chi-square test was used to analyze the clinicopathological characteristics of HGSOC patients. Survival analysis was performed using the Kaplan-Meier method, and the log-rank test was used to analyze the correlation between ETV5 expression and HGSOC patient prognosis. Univariate and multivariate analyses using the Cox regression model were conducted to determine the independent significance of relevant clinical covariates. Results Bioinformatic analysis demonstrated that ETV5 expression was significantly upregulated in OC (p < 0.05). qRT-PCR showed that ETV5 was significantly overexpressed in HGSOC tissues than in fallopian tube tissues (p < 0.05). qRT-PCR and western blotting assays demonstrated that ETV5 was relatively highly expressed in OC cell lines. ETV5 overexpression was positively associated with poor survival in HGSOC patients, therefore making it a high-risk factor for HGSOC progression. Furthermore, ETV5 promoted the proliferation, migration, and invasion capabilities of HGSOC cells. Conclusion ETV5 has a carcinogenic effect in HGSOC and can be used as a clinically effective biomarker to determine the prognosis of HGSOC patients. Supplementary Information The online version contains supplementary material available at 10.1186/s13048-021-00899-6.
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Affiliation(s)
- Lu Zhang
- Department of Pathology, NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases/The First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, 832003, China.,Department of Pathology, Shenzhen Traditional Chinese Medicine hospital, Shenzhen, 518033, China
| | - Ruiting Fu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital School of Medicine, Shihezi University, Shihezi, 832003, China
| | - Ping Liu
- Department of Pathology, NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases/The First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, 832003, China
| | - Lijun Wang
- Department of Pathology, NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases/The First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, 832003, China
| | - Weihua Liang
- Department of Pathology, NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases/The First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, 832003, China
| | - Hong Zou
- Department of Pathology, NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases/The First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, 832003, China
| | - Wei Jia
- Department of Pathology, NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases/The First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, 832003, China.
| | - Lin Tao
- Department of Pathology, NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases/The First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, 832003, China.
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14
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Rachakonda S, Hoheisel JD, Kumar R. Occurrence, functionality and abundance of the TERT promoter mutations. Int J Cancer 2021; 149:1852-1862. [PMID: 34313327 DOI: 10.1002/ijc.33750] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/14/2021] [Accepted: 07/16/2021] [Indexed: 12/18/2022]
Abstract
Telomere shortening at chromosomal ends due to the constraints of the DNA replication process acts as a tumor suppressor by restricting the replicative potential in primary cells. Cancers evade that limitation primarily through the reactivation of telomerase via different mechanisms. Mutations within the promoter of the telomerase reverse transcriptase (TERT) gene represent a definite mechanism for the ribonucleic enzyme regeneration predominantly in cancers that arise from tissues with low rates of self-renewal. The promoter mutations cause a moderate increase in TERT transcription and consequent telomerase upregulation to the levels sufficient to delay replicative senescence but not prevent bulk telomere shortening and genomic instability. Since the discovery, a staggering number of studies have resolved the discrete aspects, effects and clinical relevance of the TERT promoter mutations. The promoter mutations link transcription of TERT with oncogenic pathways, associate with markers of poor outcome and define patients with reduced survivals in several cancers. In this review, we discuss the occurrence and impact of the promoter mutations and highlight the mechanism of TERT activation. We further deliberate on the foundational question of the abundance of the TERT promoter mutations and a general dearth of functional mutations within noncoding sequences, as evident from pan-cancer analysis of the whole-genomes. We posit that the favorable genomic constellation within the TERT promoter may be less than a common occurrence in other noncoding functional elements. Besides, the evolutionary constraints limit the functional fraction within the human genome, hence the lack of abundant mutations outside the coding sequences.
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Affiliation(s)
| | - Jörg D Hoheisel
- Division of Functional Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Rajiv Kumar
- Division of Functional Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague, Czech Republic
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15
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Xue J, Li S, Shi P, Chen M, Yu S, Hong S, Li Y, Liu R, Xiao H. The ETS Inhibitor YK-4-279 Suppresses Thyroid Cancer Progression Independent of TERT Promoter Mutations. Front Oncol 2021; 11:649323. [PMID: 34221969 PMCID: PMC8242932 DOI: 10.3389/fonc.2021.649323] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 03/01/2021] [Indexed: 12/24/2022] Open
Abstract
Hotspot mutations in the core promoter region of the telomerase reverse transcriptase (TERT) gene have been well established to associate with aggressive clinical characteristics, radioiodine refractory, tumor recurrence, and mortality in thyroid cancer. Several E-twenty-six (ETS) transcription factors were reported to selectively bound to the mutant TERT promoter and activated TERT expression. In this study we aimed to investigate whether TERT promoter mutations confer sensitivity to ETS inhibitor YK-4-279 in thyroid cancer cells and whether this inhibitor could be served as a potential therapeutic agent for thyroid cancer. In vitro assays showed that YK-4-279 treatment sharply suppressed cell viability, colony formation, migration, and invasion, as well as induced cell cycle arrest and apoptosis in a panel of thyroid cancer cells. The cell viability after YK-4-279 treatment was similar between cell lines harboring mutant and wild-type TERT promoters. Furthermore, YK-4-279 treatment reduced both luciferase activity and mRNA expression of TERT independent of TERT promoter mutation status. Data from RNA-seq further revealed that YK-4-279 significantly affected biological processes including DNA replication and cell cycle. Reduced DNA helicase activity and decreased expression of several helicase genes were observed after YK-4-279 treatment. Moreover, YK-4-279 significantly inhibited tumor growth and induced apoptosis in a xenograft mice model. Thus, ETS inhibitor YK-4-279 suppressed TERT expression and conferred anti-tumor activity in a TERT promoter mutation-independent manner, and it could be a potential agent for the treatment of advanced thyroid cancers.
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Affiliation(s)
- Junyu Xue
- Department of Endocrinology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Shiyong Li
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Peijie Shi
- Department of Endocrinology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Mengke Chen
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Shuang Yu
- Department of Endocrinology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Shubin Hong
- Department of Endocrinology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Yanbing Li
- Department of Endocrinology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Rengyun Liu
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Haipeng Xiao
- Department of Endocrinology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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16
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Abstract
The identification of mutations in FGFR3 in bladder tumors in 1999 led to major interest in this receptor and during the subsequent 20 years much has been learnt about the mutational profiles found in bladder cancer, the phenotypes associated with these and the potential of this mutated protein as a target for therapy. Based on mutational and expression data, it is estimated that >80% of non-muscle-invasive bladder cancers (NMIBC) and ∼40% of muscle-invasive bladder cancers (MIBC) have upregulated FGFR3 signalling, and these frequencies are likely to be even higher if alternative splicing of the receptor, expression of ligands and changes in regulatory mechanisms are taken into account. Major efforts by the pharmaceutical industry have led to development of a range of agents targeting FGFR3 and other FGF receptors. Several of these have entered clinical trials, and some have presented very encouraging early results in advanced bladder cancer. Recent reviews have summarised the drugs and related clinical trials in this area. This review will summarise what is known about the effects of FGFR3 and its mutant forms in normal urothelium and bladder tumors, will suggest when and how this protein contributes to urothelial cancer pathogenesis and will highlight areas that may benefit from further study.
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Affiliation(s)
- Margaret A. Knowles
- Division of Molecular Medicine, Leeds Institute of Medical Research at St James’s, St James’s University Hospital, Leeds LS9 7TF, UK
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17
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McKelvey BA, Gilpatrick T, Wang Y, Timp W, Umbricht CB, Zeiger MA. Characterization of Allele-Specific Regulation of Telomerase Reverse Transcriptase in Promoter Mutant Thyroid Cancer Cell Lines. Thyroid 2020; 30:1470-1481. [PMID: 32228178 PMCID: PMC7583328 DOI: 10.1089/thy.2020.0055] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Background: Telomerase reverse transcriptase (TERT) promoter mutations play a role in carcinogenesis and are found in both tumors and cancer cell lines. TERT promoter methylation, transcription factor binding, chromatin remodeling, and alternative splicing are also known to play an integral role in TERT regulation. Methods: Using nanopore Cas9 targeted sequencing, we characterized allele-specific methylation in thyroid cancer cell lines heterozygous for the TERT promoter mutation. Furthermore, using chromatin immunoprecipitation followed by Sanger sequencing, we probed allele-specific binding of the transcription factors GABPA (GA binding protein transcription factor subunit alpha) and MYC, as well as the chromatin marks H3K4me3 and H3K27me3. Finally, using coding single nucleotide polymorphisms and the long-read sequencing, we examined complementary DNA for monoallelic expression (MAE). Results: We found the mutant TERT promoter allele to be significantly less methylated than wild type, while more methylated in the gene body in heterozygous TERT mutant cell lines. We demonstrated that the transcriptional activators GABPA and MYC bind only to the mutant TERT allele. In addition, the activating and repressive chromatin marks H3K4me3 and H3K27me3, respectively, bind mutant and wild-type alleles exclusively. Finally, in heterozygous mutant cell lines, TERT exhibits MAE from the mutant allele only. Conclusions: In summary, by employing new long-read sequencing methods, we were able to definitively demonstrate allele-specific DNA methylation, histone modifications, transcription factor binding, and the resulting monoallelic transcription in cell lines with heterozygous TERT mutations.
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Affiliation(s)
- Brittany A. McKelvey
- Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Timothy Gilpatrick
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Yongchun Wang
- Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Winston Timp
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christopher B. Umbricht
- Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Oncology, and The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Martha A. Zeiger
- Surgical Oncology Program, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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18
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Yuan X, Liu T, Xu D. Telomerase reverse transcriptase promoter mutations in thyroid carcinomas: implications in precision oncology-a narrative review. ANNALS OF TRANSLATIONAL MEDICINE 2020; 8:1244. [PMID: 33178776 PMCID: PMC7607115 DOI: 10.21037/atm-20-5024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
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.
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Affiliation(s)
- Xiaotian Yuan
- School of Medicine, Cheeloo College of Medicine, Shandong University, Jinan, China.,Department of Medicine, Division of Hematology, Bioclinicum and Center for Molecular Medicine (CMM), Karolinska Institutet and Karolinska University Hospital Solna, Solna, Sweden
| | - Tiantian Liu
- School of Medicine, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Dawei Xu
- Department of Medicine, Division of Hematology, Bioclinicum and Center for Molecular Medicine (CMM), Karolinska Institutet and Karolinska University Hospital Solna, Solna, Sweden.,Karolinska Institute-Shandong University Collaborative Laboratory for Cancer and Stem Cell Research, Jinan, China
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19
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Guterres AN, Villanueva J. Targeting telomerase for cancer therapy. Oncogene 2020; 39:5811-5824. [PMID: 32733068 PMCID: PMC7678952 DOI: 10.1038/s41388-020-01405-w] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 07/02/2020] [Accepted: 07/23/2020] [Indexed: 12/20/2022]
Abstract
Telomere maintenance via telomerase reactivation is a nearly universal hallmark of cancer cells which enables replicative immortality. In contrast, telomerase activity is silenced in most adult somatic cells. Thus, telomerase represents an attractive target for highly selective cancer therapeutics. However, development of telomerase inhibitors has been challenging and thus far there are no clinically approved strategies exploiting this cancer target. The discovery of prevalent mutations in the TERT promoter region in many cancers and recent advances in telomerase biology has led to a renewed interest in targeting this enzyme. Here we discuss recent efforts targeting telomerase, including immunotherapies and direct telomerase inhibitors, as well as emerging approaches such as targeting TERT gene expression driven by TERT promoter mutations. We also address some of the challenges to telomerase-directed therapies including potential therapeutic resistance and considerations for future therapeutic applications and translation into the clinical setting. Although much work remains to be done, effective strategies targeting telomerase will have a transformative impact for cancer therapy and the prospect of clinically effective drugs is boosted by recent advances in structural models of human telomerase.
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Affiliation(s)
- Adam N Guterres
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, PA, USA
| | - Jessie Villanueva
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, PA, USA.
- Melanoma Research Center, The Wistar Institute, Philadelphia, PA, USA.
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20
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Song YS, Park YJ. Mechanisms of TERT Reactivation and Its Interaction with BRAFV600E. Endocrinol Metab (Seoul) 2020; 35:515-525. [PMID: 32981294 PMCID: PMC7520576 DOI: 10.3803/enm.2020.304] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 07/27/2020] [Indexed: 12/26/2022] Open
Abstract
The telomerase reverse transcriptase (TERT) gene, which is repressed in most differentiated human cells, can be reactivated by somatic TERT alterations and epigenetic modulations. Moreover, the recruitment, accessibility, and binding of transcription factors also affect the regulation of TERT expression. Reactivated TERT contributes to the development and progression of cancer through telomere lengthening-dependent and independent ways. In particular, because of recent advances in high-throughput sequencing technologies, studies on genomic alterations in various cancers that cause increased TERT transcriptional activity have been actively conducted. TERT reactivation has been reported to be associated with poor prognosis in several cancers, and TERT promoter mutations are among the most potent prognostic markers in thyroid cancer. In particular, when a TERT promoter mutation coexists with the BRAFV600E mutation, these mutations exert synergistic effects on a poor prognosis. Efforts have been made to uncover the mechanisms of these synergistic interactions. In this review, we discuss the role of TERT reactivation in tumorigenesis, the mechanisms of TERT reactivation across all human cancers and in thyroid cancer, and the mechanisms of interactions between BRAFV600E and TERT promoter mutations.
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Affiliation(s)
- Young Shin Song
- Department of Internal Medicine, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Korea
| | - Young Joo Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
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21
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Stern JL, Hibshman G, Hu K, Ferrara SE, Costello JC, Kim W, Tamayo P, Cech TR, Huang FW. Mesenchymal and MAPK Expression Signatures Associate with Telomerase Promoter Mutations in Multiple Cancers. Mol Cancer Res 2020; 18:1050-1062. [PMID: 32276990 PMCID: PMC8020009 DOI: 10.1158/1541-7786.mcr-19-1244] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/29/2020] [Accepted: 04/07/2020] [Indexed: 12/19/2022]
Abstract
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.
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Affiliation(s)
- Josh Lewis Stern
- BioFrontiers Institute and the Department of Biochemistry, Howard Hughes Medical Institute, University of
- Biochemistry and Molecular Genetics, O'Neal Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Grace Hibshman
- BioFrontiers Institute and the Department of Biochemistry, Howard Hughes Medical Institute, University of
| | - Kevin Hu
- Division of Hematology/Oncology, Department of Medicine, Helen Diller Family Cancer Center; Bakar Computational Health Sciences Institute, Institute of Human Genetics, University of California San Francisco, San Francisco, California
| | - Sarah E Ferrara
- University of Colorado Comprehensive Cancer Center, Aurora, Colorado
| | - James C Costello
- University of Colorado, Anschutz Medical Campus, Department of Pharmacology, University of Colorado Comprehensive Cancer Center, Aurora, Colorado
| | - William Kim
- Division of Medical Genetics and Center for Cancer Target Discovery and Development (CTD), Moores Cancer Center, University of California San Diego, La Jolla, California
| | - Pablo Tamayo
- Division of Medical Genetics and Center for Cancer Target Discovery and Development (CTD), Moores Cancer Center, University of California San Diego, La Jolla, California.
| | - Thomas R Cech
- BioFrontiers Institute and the Department of Biochemistry, Howard Hughes Medical Institute, University of
| | - Franklin W Huang
- Division of Hematology/Oncology, Department of Medicine, Helen Diller Family Cancer Center; Bakar Computational Health Sciences Institute, Institute of Human Genetics, University of California San Francisco, San Francisco, California.
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22
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Zhang F, Wang S, Zhu J. ETS variant transcription factor 5 and c-Myc cooperate in derepressing the human telomerase gene promoter via composite ETS/E-box motifs. J Biol Chem 2020; 295:10062-10075. [PMID: 32518154 DOI: 10.1074/jbc.ra119.012130] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 06/04/2020] [Indexed: 12/19/2022] Open
Abstract
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.
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Affiliation(s)
- Fan Zhang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, Washington, USA
| | - Shuwen Wang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, Washington, USA
| | - Jiyue Zhu
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, Washington, USA
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23
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Lorbeer FK, Hockemeyer D. TERT promoter mutations and telomeres during tumorigenesis. Curr Opin Genet Dev 2020; 60:56-62. [PMID: 32163830 DOI: 10.1016/j.gde.2020.02.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/26/2020] [Accepted: 02/02/2020] [Indexed: 01/04/2023]
Abstract
Telomerase regulation and telomere shortening act as a strong tumor suppressor mechanism in human somatic cells. Point mutations in the promoter of telomerase reverse transcriptase (TERT) are the most frequent non-coding mutation in cancer. These TERT promoter mutations (TPMs) create de novo ETS factor binding sites upstream of the start codon of the gene, which can be bound by different ETS factors. TPMs can occur early during tumorigenesis and are thought to be among the first mutations in melanoma, glioblastoma and hepatocellular carcinoma. Despite their association with increased TERT levels, TPMs do not prohibit telomere shortening and TPM-harboring cancers present with short telomeres. Their short telomere length combined with their high prevalence and specificity for cancer makes TPMs an attractive target for future therapeutic exploitation of telomerase inhibition and telomere deprotection-induced cell death.
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Affiliation(s)
- Franziska K Lorbeer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Dirk Hockemeyer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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24
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Wong D, Yip S. Making heads or tails - the emergence of capicua (CIC) as an important multifunctional tumour suppressor. J Pathol 2020; 250:532-540. [PMID: 32073140 DOI: 10.1002/path.5400] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 01/31/2020] [Accepted: 02/12/2020] [Indexed: 12/24/2022]
Abstract
Capicua, encoded by the gene CIC, is an evolutionarily conserved high-mobility group-box transcription factor downstream of the receptor tyrosine kinase and mitogen-activated protein kinase pathways. It was initially discovered and studied in Drosophila. Recurrent mutations in CIC were first identified in oligodendroglioma, a subtype of low-grade glioma. Subsequent studies have identified CIC aberrations in multiple types of cancer and have established CIC as a potent tumour suppressor involved in regulating pathways related to cell growth and proliferation, invasion and treatment resistance. The most well-known and studied targets of mammalian CIC are the oncogenic E-Twenty Six transcription factors ETV1/4/5, which have been found to be elevated in cancers with CIC aberrations. Here, we review the role of CIC in normal mammalian development, oncogenesis and tumour progression, and the functional interactors that mediate them. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Derek Wong
- Molecular Oncology, British Columbia Cancer Research Center, Vancouver, British Columbia, Canada.,Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephen Yip
- Molecular Oncology, British Columbia Cancer Research Center, Vancouver, British Columbia, Canada.,Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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25
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Mu W, Provaznik J, Hackert T, Zöller M. Tspan8-Tumor Extracellular Vesicle-Induced Endothelial Cell and Fibroblast Remodeling Relies on the Target Cell-Selective Response. Cells 2020; 9:cells9020319. [PMID: 32013145 PMCID: PMC7072212 DOI: 10.3390/cells9020319] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/17/2020] [Accepted: 01/26/2020] [Indexed: 12/12/2022] Open
Abstract
Tumor cell-derived extracellular vesicles (TEX) expressing tetraspanin Tspan8-alpha4/beta1 support angiogenesis. Tspan8-alpha6/beta4 facilitates lung premetastatic niche establishment. TEX-promoted target reprogramming is still being disputed, we explored rat endothelial cell (EC) and lung fibroblast (Fb) mRNA and miRNA profile changes after coculture with TEX. TEX were derived from non-metastatic BSp73AS (AS) or metastatic BSp73ASML (ASML) rat tumor lines transfected with Tspan8 (AS-Tspan8) or Tspan8-shRNA (ASML-Tspan8kd). mRNA was analyzed by deep sequencing and miRNA by array analysis of EC and Fb before and after coculture with TEX. EC and Fb responded more vigorously to AS-Tspan8- than AS-TEX. Though EC and Fb responses differed, both cell lines predominantly responded to membrane receptor activation with upregulation and activation of signaling molecules and transcription factors. Minor TEX-initiated changes in the miRNA profile relied, at least partly, on long noncoding RNA (lncRNA) that also affected chromosome organization and mRNA processing. These analyses uncovered three important points. TEX activate target cell autonomous programs. Responses are initiated by TEX targeting units and are target cell-specific. The strong TEX-promoted lncRNA impact reflects lncRNA shuttling and location-dependent distinct activities. These informations urge for an in depth exploration on the mode of TEX-initiated target cell-specific remodeling including, as a major factor, lncRNA.
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Affiliation(s)
- Wei Mu
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- Department of General, Visceral and Transplantation Surgery, Pancreas Section, University of Heidelberg, 69120 Heidelberg, Germany
- Correspondence: (W.M.); (M.Z.); Tel.: +86-021-6384-6590 (W.M.); +49-6221-484-730 (M.Z.)
| | - Jan Provaznik
- EMBL Genomics Core Facility, 69117 Heidelberg, Germany
| | - Thilo Hackert
- Department of General, Visceral and Transplantation Surgery, Pancreas Section, University of Heidelberg, 69120 Heidelberg, Germany
| | - Margot Zöller
- Department of General, Visceral and Transplantation Surgery, Pancreas Section, University of Heidelberg, 69120 Heidelberg, Germany
- Correspondence: (W.M.); (M.Z.); Tel.: +86-021-6384-6590 (W.M.); +49-6221-484-730 (M.Z.)
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26
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McKelvey BA, Umbricht CB, Zeiger MA. Telomerase Reverse Transcriptase (TERT) Regulation in Thyroid Cancer: A Review. Front Endocrinol (Lausanne) 2020; 11:485. [PMID: 32849278 PMCID: PMC7412884 DOI: 10.3389/fendo.2020.00485] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 06/22/2020] [Indexed: 12/17/2022] Open
Abstract
Telomerase reverse transcriptase (TERT) is the catalytic subunit of the enzyme telomerase and is essential for telomerase activity. Upregulation of TERT expression and resulting telomerase activity occurs in the large majority of malignancies, including thyroid cancer. This upregulation results in continued cellular proliferation and avoidance of cellular senescence and cell death. In this review we will briefly introduce TERT and telomerase activity as it pertains to thyroid cancer and, highlight the effects of TERT on cancer cells. We will also explore in detail the different TERT regulatory strategies and how TERT is reactivated in thyroid cancer cells, specifically. These regulatory mechanisms include both activating single base pair TERT promoter mutations and epigenetic changes at the promoter, including changes in CpG methylation and histone modifications that affect chromatin structure. Further, regulation includes the allele-specific regulation of the TERT promoter in thyroid cancer cells harboring the TERT promoter mutation. These entail allele-specific transcriptional activator binding, DNA methylation, histone modifications, and mono-allelic expression of TERT. Lastly, TERT copy number alterations and alternative splicing are also implicated. Both amplifications of the TERT locus and increased full-length transcripts and decreased inactive and dominant negative isoforms result in active telomerase. Finally, the clinical significance of TERT in thyroid cancer is also reviewed.
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Affiliation(s)
- Brittany A. McKelvey
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Christopher B. Umbricht
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Martha A. Zeiger
- Surgical Oncology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: Martha A. Zeiger
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