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Zia S, Khan N, Tehreem K, Rehman N, Sami R, Baty RS, Tayeb FJ, Almashjary MN, Alsubhi NH, Alrefaei GI, Shahid R. Transcriptomic Analysis of Conserved Telomere Maintenance Component 1 (CTC1) and Its Association with Leukemia. J Clin Med 2022; 11:jcm11195780. [PMID: 36233645 PMCID: PMC9571731 DOI: 10.3390/jcm11195780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/21/2022] [Accepted: 09/26/2022] [Indexed: 11/16/2022] Open
Abstract
Telomere length (TEL) regulation is important for genome stability and is governed by the coordinated role of shelterin proteins, telomerase (TERT), and CST (CTC1/OBFC1/TEN1) complex. Previous studies have shown the association of telomerase expression with the risk of acute lymphoblastic leukemia (ALL). However, no data are available for CST association with the ALL. The current pilot study was designed to evaluate the CST expression levels in ALL. In total, 350 subjects were recruited, including 250 ALL cases and 100 controls. The subjects were stratified by age and categorized into pediatrics (1–18 years) and adults (19–54 years). TEL and expression patterns of CTC1, OBFC1, and TERT genes were determined by qPCR. The univariable logistic regression analysis was performed to determine the association of gene expression with ALL, and the results were adjusted for age and sex in multivariable analyses. Pediatric and adult cases did not reflect any change in telomere lengths relative to controls. However, expression of CTC1, OBFC1, and TERT genes were induced among ALL cases. Multivariable logistic regression analyses showed association of CTC1 with ALL in pediatric [β estimate (standard error (SE)= −0.013 (0.007), p = 0.049, and adults [0.053 (0.023), p = 0.025]. The association of CTC1 remained significant when taken together with OBFC1 and TERT in a multivariable model. Furthermore, CTC1 showed significant association with B-cell ALL [−0.057(0.017), p = 0.002) and T-cell ALL [−0.050 (0.018), p = 0.008] in pediatric group while no such association was noted in adults. Together, our findings demonstrated that telomere modulating genes, particularly CTC1, are strongly associated with ALL. Therefore, CTC1 can potentially be used as a risk biomarker for the identification of ALL in both pediatrics and adults.
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Affiliation(s)
- Saadiya Zia
- Department of Biosciences, COMSATS University Islamabad (CUI), Islamabad 45550, Pakistan
- Department of Biochemistry, University of Agriculture Faisalabad, Faisalabad 38000, Pakistan
| | - Netasha Khan
- Department of Biosciences, COMSATS University Islamabad (CUI), Islamabad 45550, Pakistan
| | - Komal Tehreem
- Department of Biosciences, COMSATS University Islamabad (CUI), Islamabad 45550, Pakistan
| | - Nazia Rehman
- Department of Biosciences, COMSATS University Islamabad (CUI), Islamabad 45550, Pakistan
| | - Rokayya Sami
- Department of Food Science and Nutrition, College of Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Roua S. Baty
- Department of Biotechnology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Faris J. Tayeb
- Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, University of Tabuk, Tabuk 47713, Saudi Arabia
| | - Majed N. Almashjary
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 22254, Saudi Arabia
- Hematology Research Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 22254, Saudi Arabia
| | - Nouf H. Alsubhi
- Biological Sciences Department, College of Science and Arts, King Abdulaziz University, Rabigh 21911, Saudi Arabia
| | - Ghadeer I. Alrefaei
- Department of Biology, College of Science, University of Jeddah, P.O. Box 80327, Jeddah 21589, Saudi Arabia
| | - Ramla Shahid
- Department of Biosciences, COMSATS University Islamabad (CUI), Islamabad 45550, Pakistan
- Correspondence:
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Telomerase ( hTERT) Overexpression Reveals a Promising Prognostic Biomarker and Therapeutical Target in Different Clinical Subtypes of Pediatric Acute Lymphoblastic Leukaemia. Genes (Basel) 2021; 12:genes12101632. [PMID: 34681025 PMCID: PMC8535500 DOI: 10.3390/genes12101632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/06/2021] [Accepted: 10/12/2021] [Indexed: 02/07/2023] Open
Abstract
Acute Lymphoblastic Leukemia (ALL) is a neoplasm of the hematopoietic system defined as a clonal expansion of an abnormal lymphoid precursor cell. It mostly affects children under five years of age and is the most common tumor to afflict pediatric patients. The expression of the human telomerase gene (hTERT) in patients with ALL has been studied as a biomarker and could become a new therapeutic target. We evaluate the role of hTERT gene expression in ALL pediatric patients, through quantitative real-time PCR technique, and the possible correlation between hTERT expression and clinical variables: gender, age, white blood cells (WBC), gene fusions, and immunophenotyping. The analysis between healthy controls and ALL patients (N = 244) was statistically significant (p < 0.001), demonstrating hTERT overexpression in these patients. In comparison with the usual set of clinical variables, the data were not statistically significant (p > 0.05), indicating that hTERT is equally overexpressed among patients regardless of gender, age, gene fusions, and immunophenotyping. Moreover, patients who presented a higher hTERT expression level had a significant (p < 0.0001) lower overall survival rate. In summary, hTERT expression emerges as an important molecular pathway in leukemogenesis regardless patient's clinical variables, thus, the data here presented pointed it as a valuable biomarker in pediatric acute lymphoblastic leukemia and a promising target for new therapeutic and prognostic measures.
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Targeting Telomere Biology in Acute Lymphoblastic Leukemia. Int J Mol Sci 2021; 22:ijms22136653. [PMID: 34206297 PMCID: PMC8268026 DOI: 10.3390/ijms22136653] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/02/2021] [Accepted: 06/14/2021] [Indexed: 01/19/2023] Open
Abstract
Increased cell proliferation is a hallmark of acute lymphoblastic leukemia (ALL), and genetic alterations driving clonal proliferation have been identified as prognostic factors. To evaluate replicative history and its potential prognostic value, we determined telomere length (TL) in lymphoblasts, B-, and T-lymphocytes, and measured telomerase activity (TA) in leukocytes of patients with ALL. In addition, we evaluated the potential to suppress the in vitro growth of B-ALL cells by the telomerase inhibitor imetelstat. We found a significantly lower TL in lymphoblasts (4.3 kb in pediatric and 2.3 kb in adult patients with ALL) compared to B- and T-lymphocytes (8.0 kb and 8.2 kb in pediatric, and 6.4 kb and 5.5 kb in adult patients with ALL). TA in leukocytes was 3.2 TA/C for pediatric and 0.7 TA/C for adult patients. Notably, patients with high-risk pediatric ALL had a significantly higher TA of 6.6 TA/C compared to non-high-risk patients with 2.2 TA/C. The inhibition of telomerase with imetelstat ex vivo led to significant dose-dependent apoptosis of B-ALL cells. These results suggest that TL reflects clonal expansion and indicate that elevated TA correlates with high-risk pediatric ALL. In addition, telomerase inhibition induces apoptosis of B-ALL cells cultured in vitro. TL and TA might complement established markers for the identification of patients with high-risk ALL. Moreover, TA seems to be an effective therapeutic target; hence, telomerase inhibitors, such as imetelstat, may augment standard ALL treatment.
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Gorenjak V, Petrelis AM, Stathopoulou MG, Visvikis-Siest S. Telomere length determinants in childhood. Clin Chem Lab Med 2021; 58:162-177. [PMID: 31465289 DOI: 10.1515/cclm-2019-0235] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 07/30/2019] [Indexed: 01/16/2023]
Abstract
Telomere length (TL) is a dynamic marker that reflects genetic predispositions together with the environmental conditions of an individual. It is closely related to longevity and a number of pathological conditions. Even though the extent of telomere research in children is limited compared to that of adults, there have been a substantial number of studies providing first insights into child telomere biology and determinants. Recent discoveries revealed evidence that TL is, to a great extent, determined already in childhood and that environmental conditions in adulthood have less impact than first believed. Studies have demonstrated that large inter-individual differences in TL are present among newborns and are determined by diverse factors that influence intrauterine development. The first years of child growth are associated with high cellular turnover, which results in fast shortening of telomeres. The rate of telomere loss becomes stable in early adulthood. In this review article we summarise the existing knowledge on telomere dynamics during the first years of childhood, highlighting the conditions that affect newborn TL. We also warn about the knowledge gaps that should be filled to fully understand the regulation of telomeres, in order to implement them as biomarkers for use in diagnostics or treatment.
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Affiliation(s)
| | | | | | - Sophie Visvikis-Siest
- University of Lorraine, Inserm, IGE-PCV, Nancy, France.,Department of Internal Medicine and Geriatrics, CHU Technopôle Nancy-Brabois, Vandoeuvre-lès-Nancy, France
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da Silva GG, Morais KS, Arcanjo DS, de Oliveira DM. Clinical Relevance of Alternative Lengthening of Telomeres in Cancer. Curr Top Med Chem 2020; 20:485-497. [PMID: 31924155 DOI: 10.2174/1568026620666200110112854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 12/11/2019] [Accepted: 12/16/2019] [Indexed: 11/22/2022]
Abstract
The alternative lengthening of telomere (ALT) is a pathway responsible for cell immortalization in some kinds of tumors. Since the first description of ALT is relatively recent in the oncology field, its mechanism remains elusive, but recent works address ALT-related proteins or cellular structures as potential druggable targets for more specific and efficient antitumor therapies. Moreover, some new generation compounds for antitelomerase therapy in cancer were able to provoke acquisition of ALT phenotype in treated tumors, enhancing the importance of studies on this alternative lengthening of the telomere. However, ALT has been implicated in different - sometimes opposite - outcomes, according to the tumor type studied. Then, in order to design and develop new drugs for ALT+ cancer in an effective way, it is crucial to understand its clinical implications. In this review, we gathered works published in the last two decades to highlight the clinical relevance of ALT on oncology.
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Affiliation(s)
- Guilherme G da Silva
- Department of Biological Basis of Health Sciences, University of Brasilia, Ceilandia Campus, Federal District, Brazil
| | - Karollyne S Morais
- Laboratory of Molecular Pathology of Cancer, University of Brasilia, Federal District, Brazil
| | - Daniel S Arcanjo
- Department of Biological Basis of Health Sciences, University of Brasilia, Ceilandia Campus, Federal District, Brazil
| | - Diêgo M de Oliveira
- Department of Biological Basis of Health Sciences, University of Brasilia, Ceilandia Campus, Federal District, Brazil.,Laboratory of Molecular Pathology of Cancer, University of Brasilia, Federal District, Brazil
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Dorris K, Sobo M, Onar-Thomas A, Panditharatna E, Stevenson CB, Gardner SL, Dewire MD, Pierson CR, Olshefski R, Rempel SA, Goldman S, Miles L, Fouladi M, Drissi R. Prognostic significance of telomere maintenance mechanisms in pediatric high-grade gliomas. J Neurooncol 2014; 117:67-76. [PMID: 24477622 DOI: 10.1007/s11060-014-1374-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 01/19/2014] [Indexed: 02/06/2023]
Abstract
Children with high-grade glioma, including diffuse intrinsic pontine glioma (DIPG), have a poor prognosis despite multimodal therapy. Identifying novel therapeutic targets is critical to improve their outcome. We evaluated prognostic roles of telomere maintenance mechanisms in children with HGG, including DIPG. A multi-institutional retrospective study was conducted involving 50 flash-frozen HGG (35 non-brainstem; 15 DIPG) tumors from 45 children (30 non-brainstem; 15 DIPG). Telomerase activity, expression of hTERT mRNA (encoding telomerase catalytic component) and TERC (telomerase RNA template) and alternative lengthening of telomeres (ALT) mechanism were assayed. Cox Proportional Hazard regression analyses assessed association of clinical and pathological variables, TERC and hTERT levels, telomerase activity, and ALT use with progression-free or overall survival (OS). High TERC and hTERT expression was detected in 13/28 non-brainstem HGG samples as compared to non-neoplastic controls. High TERC and hTERT expression was identified in 13/15 and 11/15 DIPG samples, respectively, compared to controls. Evidence of ALT was noted in 3/11 DIPG and 10/19 non-brainstem HGG specimens. ALT and telomerase use were identified in 4/19 non-brainstem HGG and 2/11 DIPG specimens. In multivariable analyses, increased TERC and hTERT levels were associated with worse OS in patients with non-brainstem HGG, after controlling for tumor grade or resection extent. Children with HGG and DIPG, have increased hTERT and TERC expression. In children with non-brainstem HGG, increased TERC and hTERT expression levels are associated with a worse OS, making telomerase a promising potential therapeutic target in pediatric HGG.
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Affiliation(s)
- Kathleen Dorris
- Division of Oncology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, MLC 7013, 3333 Burnet Ave, Cincinnati, OH, 45229, USA
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7
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Owens C, Abbott LS, Gupta AA. Optimal management of Ewing sarcoma family of tumors: recent developments in systemic therapy. Paediatr Drugs 2013; 15:473-92. [PMID: 23760780 DOI: 10.1007/s40272-013-0037-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Ewing sarcoma family of tumors (ESFT) is defined by cell surface expression of CD99 and a translocation involving EWS and an ETS partner. Cytotoxic chemotherapy remains the benchmark of first- and second-line therapy, and although the majority of patients with localized disease are cured, almost one third of patients relapse or progress from their disease. Moreover, cure remains elusive in most patients who present with distant metastases. In recent years, the ESFT literature has been dominated by reports of attempts at modulating the insulin-like growth factor (IGF) receptor (IGFR). Unfortunately, three phase II studies examining inhibiting antibodies to IGFR-1 published disappointing results. Whether these results were due to failure to modulate the pathway or other limitations in study design and/or patient selection remain unclear. Other novel strategies currently being investigated in ESFT include tyrosine kinase, mammalian target of rapamycin (mTOR), and poly(ADP-ribose) polymerase (PARP) inhibitors.
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Affiliation(s)
- Cormac Owens
- The Division of Hematology/Oncology, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, M5G 1N6, Canada,
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Thompson PA, Drissi R, Muscal JA, Panditharatna E, Fouladi M, Ingle AM, Ahern CH, Reid JM, Lin T, Weigel BJ, Blaney SM. A phase I trial of imetelstat in children with refractory or recurrent solid tumors: a Children's Oncology Group Phase I Consortium Study (ADVL1112). Clin Cancer Res 2013; 19:6578-84. [PMID: 24097866 DOI: 10.1158/1078-0432.ccr-13-1117] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Imetelstat is a covalently-lipidated 13-mer thiophosphoramidate oligonucleotide that acts as a potent specific inhibitor of telomerase. It binds with high affinity to the template region of the RNA component of human telomerase (hTERC) and is a competitive inhibitor of telomerase enzymatic activity. The purpose of this study was to determine the recommended phase II dose of imetelstat in children with recurrent or refractory solid tumors. EXPERIMENTAL DESIGN Imetelstat was administered intravenously more than two hours on days 1 and 8, every 21 days. Dose levels of 225, 285, and 360 mg/m(2) were evaluated, using the rolling-six design. Imetelstat pharmacokinetic and correlative biology studies were also performed during the first cycle. RESULTS Twenty subjects were enrolled (median age, 14 years; range, 3-21). Seventeen were evaluable for toxicity. The most common toxicities were neutropenia, thrombocytopenia, and lymphopenia, with dose-limiting myelosuppression in 2 of 6 patients at 360 mg/m(2). Pharmacokinetics is dose dependent with a lower clearance at the highest dose level. Telomerase inhibition was observed in peripheral blood mononuclear cells at 285 and 360 mg/m(2). Two confirmed partial responses, osteosarcoma (n = 1) and Ewing sarcoma (n = 1), were observed. CONCLUSIONS The recommended phase II dose of imetelstat given on days 1 and 8 of a 21-day cycle is 285 mg/m(2).
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Affiliation(s)
- Patrick A Thompson
- Authors' Affiliations: Texas Children's Cancer Center and Department of Pediatrics; Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas; Division of Oncology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Children's Oncology Group, Arcadia; Geron Corporation, Menlo Park, California; Department of Oncology, Mayo Clinic, Rochester; and Department of Pediatrics, Hematology-Oncology, University of Minnesota, Minneapolis, Minnesota
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Tumor protein p53 (TP53) testing and Li-Fraumeni syndrome : current status of clinical applications and future directions. Mol Diagn Ther 2013; 17:31-47. [PMID: 23355100 DOI: 10.1007/s40291-013-0020-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Prevalent as an acquired abnormality in cancer, the role of tumor protein p53 (TP53) as a germline mutation continues to evolve. The clinical impact of a germline TP53 mutation is often dramatic and affects the full life course, with a propensity to develop rare tumors in childhood and multiple common cancers of unexpectedly early onset in adulthood. In this article, we review the clinical relevance of germline mutations in the TP53 tumor suppressor gene to current healthcare practice, including the optimal ways to identify patients with Li-Fraumeni syndrome (LFS), to recognize the core cancers associated with LFS, and to develop strategies for early detection of LFS-associated tumors. Several TP53-targeted approaches to improve outcomes in LFS patients are also reviewed. A case report is used to highlight special TP53 testing dilemmas and unique challenges associated with genetic testing decisions in the current age of rapidly advancing genomic technologies.
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Parker M, Chen X, Bahrami A, Dalton J, Rusch M, Wu G, Easton J, Cheung NK, Dyer M, Mardis ER, Wilson RK, Mullighan C, Gilbertson R, Baker SJ, Zambetti G, Ellison DW, Downing JR, Zhang J. Assessing telomeric DNA content in pediatric cancers using whole-genome sequencing data. Genome Biol 2012; 13:R113. [PMID: 23232254 PMCID: PMC3580411 DOI: 10.1186/gb-2012-13-12-r113] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 11/22/2012] [Accepted: 12/11/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Telomeres are the protective arrays of tandem TTAGGG sequence and associated proteins at the termini of chromosomes. Telomeres shorten at each cell division due to the end-replication problem and are maintained above a critical threshold in malignant cancer cells to prevent cellular senescence or apoptosis. With the recent advances in massive parallel sequencing, assessing telomere content in the context of other cancer genomic aberrations becomes an attractive possibility. We present the first comprehensive analysis of telomeric DNA content change in tumors using whole-genome sequencing data from 235 pediatric cancers. RESULTS To measure telomeric DNA content, we counted telomeric reads containing TTAGGGx4 or CCCTAAx4 and normalized to the average genomic coverage. Changes in telomeric DNA content in tumor genomes were clustered using a Bayesian Information Criterion to determine loss, no change, or gain. Using this approach, we found that the pattern of telomeric DNA alteration varies dramatically across the landscape of pediatric malignancies: telomere gain was found in 32% of solid tumors, 4% of brain tumors and 0% of hematopoietic malignancies. The results were validated by three independent experimental approaches and reveal significant association of telomere gain with the frequency of somatic sequence mutations and structural variations. CONCLUSIONS Telomere DNA content measurement using whole-genome sequencing data is a reliable approach that can generate useful insights into the landscape of the cancer genome. Measuring the change in telomeric DNA during malignant progression is likely to be a useful metric when considering telomeres in the context of the whole genome.
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Affiliation(s)
- Matthew Parker
- Department of Computational Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Xiang Chen
- Department of Computational Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Armita Bahrami
- Department of Pathology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - James Dalton
- Department of Pathology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Michael Rusch
- Department of Computational Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Gang Wu
- Department of Computational Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - John Easton
- The Pediatric Cancer Genome Project, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Nai-Kong Cheung
- Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Michael Dyer
- Department of Developmental Neurobiology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Elaine R Mardis
- The Genome Center at Washington University, Washington University, 4444 Forest Park Ave, St Louis, Missouri 63108, USA
- Department of Genetics, Washington University, 4444 Forest Park Ave, St Louis, Missouri 63108, USA
| | - Richard K Wilson
- The Genome Center at Washington University, Washington University, 4444 Forest Park Ave, St Louis, Missouri 63108, USA
- Department of Genetics, Washington University, 4444 Forest Park Ave, St Louis, Missouri 63108, USA
| | - Charles Mullighan
- Department of Pathology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Richard Gilbertson
- Department of Developmental Neurobiology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Suzanne J Baker
- Department of Developmental Neurobiology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Gerard Zambetti
- Department of Biochemistry, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - David W Ellison
- Department of Pathology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - James R Downing
- Department of Pathology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Jinghui Zhang
- Department of Computational Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
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Rodriguez FJ, Lim KS, Bowers D, Eberhart CG. Pathological and molecular advances in pediatric low-grade astrocytoma. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2012; 8:361-79. [PMID: 23121055 DOI: 10.1146/annurev-pathol-020712-164009] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Pediatric low-grade astrocytomas are the most common brain tumors in children. They can have similar microscopic and clinical features, making accurate diagnosis difficult. For patients whose tumors are in locations that do not permit full resection, or those with an intrinsically aggressive biology, more effective therapies are required. Until recently, little was known about the molecular changes that drive the initiation and growth of pilocytic and other low-grade astrocytomas beyond the association of a minority of cases, primarily in the optic nerve, with neurofibromatosis type 1. Over the past several years, a wide range of studies have implicated the BRAF oncogene and other members of this signaling cascade in the pathobiology of pediatric low-grade astrocytoma. In this review, we attempt to summarize this rapidly developing field and discuss the potential for translating our growing molecular knowledge into improved diagnostic and prognostic biomarkers and new targeted therapies.
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Affiliation(s)
- Fausto J Rodriguez
- Department of Pathology, Johns Hopkins UniversitySchool of Medicine, Baltimore, Maryland 21205, USA
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12
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Taboski MAS, Sealey DCF, Dorrens J, Tayade C, Betts DH, Harrington L. Long telomeres bypass the requirement for telomere maintenance in human tumorigenesis. Cell Rep 2012; 1:91-8. [PMID: 22832159 PMCID: PMC3406325 DOI: 10.1016/j.celrep.2011.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 12/06/2011] [Accepted: 12/15/2011] [Indexed: 01/03/2023] Open
Abstract
Despite the importance of telomere maintenance in cancer cell survival via the elongation of telomeres by telomerase reverse transcriptase (TERT) or alternative lengthening of telomeres (ALT), it had not been tested directly whether telomere maintenance is dispensable for human tumorigenesis. We engineered human tumor cells containing loxP-flanked hTERT to enable extensive telomere elongation prior to complete hTERT excision. Despite unabated telomere erosion, hTERT-excised cells formed tumors in mice and proliferated in vitro for up to 1 year. Telomerase reactivation or ALT was not observed, and the eventual loss of telomeric signal coincided with loss of tumorigenic potential and cell viability. Crisis was averted via the reintroduction of active but not inactive hTERT. Thus, telomere maintenance is dispensable for human tumorigenesis when telomere reserves are long. Yet, despite telomere instability and the presence of oncogenic RAS, human tumors remain susceptible to crisis induced by critically short telomeres.
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Affiliation(s)
- Michael A. S. Taboski
- Campbell Family Institute for Cancer Research and
Department of Medical Biophysics, Ontario Cancer Institute, University of Toronto,
Toronto, M5G 2C1, Canada
| | - David C. F. Sealey
- Campbell Family Institute for Cancer Research and
Department of Medical Biophysics, Ontario Cancer Institute, University of Toronto,
Toronto, M5G 2C1, Canada
| | - Jennifer Dorrens
- Wellcome Trust Centre for Cell Biology, School of
Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JR, United
Kingdom
| | - Chandrakant Tayade
- Biomedical Sciences, Ontario Veterinary College, University
of Guelph, Guelph, N1G 2W1, Canada
| | - Dean H. Betts
- Biomedical Sciences, Ontario Veterinary College, University
of Guelph, Guelph, N1G 2W1, Canada
| | - Lea Harrington
- Campbell Family Institute for Cancer Research and
Department of Medical Biophysics, Ontario Cancer Institute, University of Toronto,
Toronto, M5G 2C1, Canada
- Wellcome Trust Centre for Cell Biology, School of
Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JR, United
Kingdom
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Zhang Y, Cai L, Wei RX, Hu H, Jin W, Zhu XB. Different expression of alternative lengthening of telomere (ALT)-associated proteins/mRNAs in osteosarcoma cell lines. Oncol Lett 2011; 2:1327-1332. [PMID: 22848311 DOI: 10.3892/ol.2011.403] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 08/26/2011] [Indexed: 12/21/2022] Open
Abstract
Tumors, including osteosarcoma (OS), are capable of evading senescence and cell death, which is caused by telomere loss with cell division. Alternative lengthening of telomeres (ALT) is considered as the main telomere maintenance mechanism in OS. In this study, we investigated the expression of ALT-associated proteins and mRNAs in human OS cell lines. Western blotting was used to detect the protein expression in OS cell lines, while the expression of mRNA was determined by reverse-transcriptase PCR and quantitative real-time PCR analysis. Whole-genome expression arrays were used to analyze the expression of all the mRNAs involved in telomere maintenance mechanisms (TMMs) including human telomerase reverse transcriptase, promyelocytic leukemia proteins and other related proteins. OS and normal cell lines do not express telomerase reverse transcriptase (hTERT) as a key subunit of telomerase, although they show varying levels of ALT-associated proteins and mRNAs such as PML, Rad52, MRE11 and FEN1 by Western blotting and quantitative real-time PCR analysis. A number of mRNAs that play essential roles in ALT are expressed more in OS cell lines than in the osteoblast cell line, as shown by whole-genome expression arrays. In conclusion, OS cell lines maintain their telomere length primarily through the ALT mechanism. There are numerous other proteins that regulate this process in OS; therefore, anti-ALT therapy may be a more effective method to treat OS than anti-telomerase therapy.
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Affiliation(s)
- Yi Zhang
- Department of Orthopedics, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
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14
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Venturini L, Daidone MG, Motta R, Collini P, Spreafico F, Terenziani M, Piva L, Radice P, Perotti D, Zaffaroni N. Telomere maintenance in wilms tumors: First evidence for the presence of alternative lengthening of telomeres mechanism. Genes Chromosomes Cancer 2011; 50:823-9. [DOI: 10.1002/gcc.20903] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 06/10/2011] [Indexed: 11/08/2022] Open
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15
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Abstract
Pediatric high grade gliomas (HGG) remain difficult to cure despite recent advances in imaging, neurosurgery, and radiation. Current treatment modalities have demonstrated only modest survival benefit. Research utilizing molecular biologic techniques reveals that the phenotype of HGG is complex and results from dysregulation of numerous inter-related cellular pathways. Knowledge of potential molecular targets along dysregulated pathways has led to the development of novel and highly specific targeted therapies, which include small molecule inhibitors. This article will review small molecule inhibition of cellular pathways involved in gliomagenesis, challenges to small molecule therapy, and future directions in the use of this therapy.
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Affiliation(s)
- Betty Herrington
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Children's Hospital Boston, Boston, Massachusetts 02115, USA
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16
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Zhou P, Fang DC, Chen B, Mao GP, Liu WW, Cao CP, Bu XH, Zhang QJ. Cloning of a group of telomere-associated proteins. Shijie Huaren Xiaohua Zazhi 2008; 16:1507-1512. [DOI: 10.11569/wcjd.v16.i14.1507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To elucidate the biological function and molecular mechanism of telomerase in immortal and/or tumor cells.
METHODS: Based on the principle of the yeast two-hybrid technology, the recombinant of human telomerase catalytic subunit bait fusion gene was constructed by DNA recombination technique, which was employed to screen cDNA libraries. The positive clones were confirmed by β-galactosidase colony-lift filter assay and furthermore the obtained plasmids cDNA sequences were compared with the isogenous sequences in GenBank.
RESULTS: The gene phenotypes of AH109 and Y187 yeast strains were stable and there was no leak expression of His. The recombinant of human telomerase catalytic subunit bait fusion gene, which was named as pGBKT7-hTERT, was constructed, and its bait fusion protein had no toxic effects on AH109 yeast cells and no activation effect on the autonomous reporter gene LacZ. Twenty-eight Ade+, Leu+, Trp+, and His+ clones were screened from the cDNA libraries and 12 Ade+, His+ and LacZ+ clones were obtained by the print analysis of β-galactosidase colony-lift filter assay. Of the 12 positive clones, 5 library plasmids possessed the effect of autonomously activating the reporter gene, so they were removed. There were 7 true positive clones among the library plasmids, 2 of which were found repeated after sequencing. The six obtained plasmids cDNA sequences were compared with the isogenous sequences in GenBank by Blast software via Internet. Finally, 6 recorded cDNA sequences were obtained, including T-STAR, PAWR, I-1, SMARCB1, LOXL3 and HKR3.
CONCLUSION: The 6 obtained telomere-associated proteins may help us understand the structure of telomerase holoenzyme and the biological function and molecular mechanism of telomerase in tumor and/or immortal cells, providing a theoretical basis for the tumor genesis, aging and prevention.
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