251
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Simpson K, Jones RE, Grimstead JW, Hills R, Pepper C, Baird DM. Telomere fusion threshold identifies a poor prognostic subset of breast cancer patients. Mol Oncol 2015; 9:1186-93. [PMID: 25752197 PMCID: PMC4449122 DOI: 10.1016/j.molonc.2015.02.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 01/29/2015] [Accepted: 02/06/2015] [Indexed: 11/05/2022] Open
Abstract
Telomere dysfunction and fusion can drive genomic instability and clonal evolution in human tumours, including breast cancer. Telomere length is a critical determinant of telomere function and has been evaluated as a prognostic marker in several tumour types, but it has yet to be used in the clinical setting. Here we show that high‐resolution telomere length analysis, together with a specific telomere fusion threshold, is highly prognostic for overall survival in a cohort of patients diagnosed with invasive ductal carcinoma of the breast (n = 120). The telomere fusion threshold defined a small subset of patients with an extremely poor clinical outcome, with a median survival of less than 12 months (HR = 21.4 (7.9–57.6), P < 0.0001). Furthermore, this telomere length threshold was independent of ER, PGR, HER2 status, NPI, or grade and was the dominant variable in multivariate analysis. We conclude that the fusogenic telomere length threshold provides a powerful, independent prognostic marker with clinical utility in breast cancer. Larger prospective studies are now required to determine the optimal way to incorporate high‐resolution telomere length analysis into multivariate prognostic algorithms for patients diagnosed with breast cancer. High‐resolution telomere length analysis is highly prognostic for overall survival. Independent of ER, PGR, HER2 status, NPI and grade. Dominant variable in multivariate analysis.
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Affiliation(s)
- K Simpson
- Institute of Cancer & Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - R E Jones
- Institute of Cancer & Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - J W Grimstead
- Institute of Cancer & Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - R Hills
- Institute of Cancer & Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - C Pepper
- Institute of Cancer & Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - D M Baird
- Institute of Cancer & Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
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252
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The role of telomeres in predicting individual radiosensitivity of patients with cancer in the era of personalized radiotherapy. Cancer Treat Rev 2015; 41:354-60. [PMID: 25704912 DOI: 10.1016/j.ctrv.2015.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 02/02/2015] [Accepted: 02/04/2015] [Indexed: 02/06/2023]
Abstract
Radiotherapy plays a key role in cancer treatments, but tumor cell death differs from one tumor to another. The response of patients to radiotherapy varies considerably and adverse side effects are difficult to prevent. The mechanisms involved in the heterogeneity of this response are not well understood. In order to enhance the efficacy and safety of radiotherapy, it is important to identify subpopulations most at risk of developing a late adverse response to radiotherapy. Telomeres are composed of multiple repeats of a unique sequence of nucleotides forming a TTAGGG pattern. They protect chromosomes from end-to-end fusion and maintain genomic stability. Telomeres have been shown to be extremely sensitive to radiotherapy especially because of their atypical DNA damage repair response, which includes partial inhibition of the non-homologous end joining repair pathway. Ionizing Radiation (IR)-induced damage to telomere DNA could lead to chromosome instability and the initiation or progression of tumor processes. Telomeres could thus be a reliable marker of IR exposure and as such become a new parameter for predicting radiosensitivity. Furthermore, short telomeres are more sensitive to radiotherapy, which could partially explain differences in tumor cell death and in inter-individual sensitivity to radiotherapy. Telomere length could be used to identify subpopulations of patients who could benefit from higher or lower doses per fraction. Finally, pharmacological interference with tumor-cell telomere biology to reduce telomere length and/or telomere stability could also enhance the effectiveness and safety of radiotherapy. Telomeres could play a key role in radiotherapy in the era of personalized medicine.
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253
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Feng F, Yang Y, Li Z, Song J, Zhu H, Wang L, Zhao Y, Xu D, Wu Y, Wu Y, Wang W. Changes in telomere length and telomerase activity in human bronchial epithelial cells induced by coal tar pitch extract. Toxicol Res (Camb) 2015. [DOI: 10.1039/c5tx00121h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Coal tar pitch is a confirmed human carcinogen and is composed mainly of polycyclic aromatic hydrocarbons.
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254
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Miyazaki Y, Yoshida N, Nozaki T, Inoue H, Kikuchi K, Kusama K. Telomerase activity in the occurrence and progression of oral squamous cell carcinoma. J Oral Sci 2015; 57:295-303. [DOI: 10.2334/josnusd.57.295] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Affiliation(s)
- Yuji Miyazaki
- Division of Pathology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry
| | - Noriaki Yoshida
- Division of Pathology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry
| | - Tadashige Nozaki
- Division of Pathology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry
- Department of Pharmacology, Osaka Dental University
| | - Harumi Inoue
- Division of Pathology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry
| | - Kentaro Kikuchi
- Division of Pathology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry
| | - Kaoru Kusama
- Division of Pathology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry
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255
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Roe S, Gunaratnam M, Spiteri C, Sharma P, Alharthy RD, Neidle S, Moses JE. Synthesis and biological evaluation of hybrid acridine-HSP90 ligand conjugates as telomerase inhibitors. Org Biomol Chem 2015; 13:8500-4. [DOI: 10.1039/c5ob01177a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The synthesis and biological evaluation of a series of bifunctional acridine-HSP90 inhibitor ligands as telomerase inhibitors is herein described.
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Affiliation(s)
- S. Roe
- School of Chemistry
- University of Nottingham
- University Park
- UK
| | | | - C. Spiteri
- School of Chemistry
- University of Nottingham
- University Park
- UK
| | - P. Sharma
- School of Chemistry
- University of Nottingham
- University Park
- UK
| | - R. D. Alharthy
- Department of Chemistry
- King Abdulaziz University
- Saudi Arabia
| | - S. Neidle
- School of Pharmacy
- University College London
- UK
| | - J. E. Moses
- School of Chemistry
- University of Nottingham
- University Park
- UK
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256
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Abstract
Telomeres form protective caps at the ends of linear chromosomes to prevent nucleolytic degradation, end-to-end fusion, irregular recombination, and chromosomal instability. Telomeres are composed of repetitive DNA sequences (TTAGGG)n in humans, that are bound by specialized telomere binding proteins. Telomeres lose capping function in response to telomere shortening, which occurs during each division of cells that lack telomerase activity-the enzyme that can synthesize telomeres de novo. Telomeres have a dual role in cancer: telomere shortening can lead to induction of chromosomal instability and to the initiation of tumors, however, initiated tumors need to reactivate telomerase in order to stabilize chromosomes and to gain immortal growth capacity. In this review, we summarize current knowledge on the role of telomeres in the maintenance of chromosomal stability and carcinogenesis.
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257
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Kim HS, Hong JS. Telomere length and telomerase activity are related with immortalization frequency but not with replicative senescence in mammalian embryonic fibroblasts, except human embryonic fibroblasts. Anim Cells Syst (Seoul) 2014. [DOI: 10.1080/19768354.2014.987815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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258
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Trend of telomerase activity change during human iPSC self-renewal and differentiation revealed by a quartz crystal microbalance based assay. Sci Rep 2014; 4:6978. [PMID: 25381797 PMCID: PMC4225532 DOI: 10.1038/srep06978] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 10/20/2014] [Indexed: 11/09/2022] Open
Abstract
Telomerase plays an important role in governing the life span of cells for its capacity to extend telomeres. As high activity of telomerase has been found in stem cells and cancer cells specifically, various methods have been developed for the evaluation of telomerase activity. To overcome the time-consuming procedures and complicated manipulations of existing methods, we developed a novel method named Telomeric Repeat Elongation Assay based on Quartz crystal microbalance (TREAQ) to monitor telomerase activity during the self-renewal and differentiation of human induced pluripotent stem cells (hiPSCs). TREAQ results indicated hiPSCs possess invariable telomerase activity for 11 passages on Matrigel and a steady decline of telomerase activity when differentiated for different periods, which is confirmed with existing golden standard method. The pluripotency of hiPSCs during differentiation could be estimated through monitoring telomerase activity and compared with the expression levels of markers of pluripotency gene via quantitative real time PCR. Regular assessment for factors associated with pluripotency or stemness was expensive and requires excessive sample consuming, thus TREAQ could be a promising alternative technology for routine monitoring of telomerase activity and estimate the pluripotency of stem cells.
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259
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Kuszel L, Trzeciak T, Richter M, Czarny-Ratajczak M. Osteoarthritis and telomere shortening. J Appl Genet 2014; 56:169-76. [PMID: 25366419 PMCID: PMC4412548 DOI: 10.1007/s13353-014-0251-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 10/04/2014] [Accepted: 10/08/2014] [Indexed: 11/16/2022]
Abstract
Osteoarthritis is the most common disease of joints caused by degradation of articular cartilage and subchondral bone. It is classified as primary form with unknown cause and as secondary form with known etiology. Genetic and epigenetic factors interact with environmental factors and contribute to the development of primary osteoarthritis. Thus far, many polymorphisms associated with osteoarthritis have been identified and recent studies also indicate the involvement of epigenetic factors (e.g., telomere shortening) in the initiation of this disorder. Accelerated shortening of telomeres was detected in osteoarthritis and other age-related diseases. Studies revealed that telomere length is severely reduced in blood leukocytes and chondrocytes of patients with osteoarthritis, and this may contribute to the initiation and development of osteoarthritis, whose major cause is still unknown.
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Affiliation(s)
- Lukasz Kuszel
- Department of Medical Genetics, Poznan University of Medical Sciences, Rokietnicka 8, 60-806, Poznan, Poland
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260
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A retrospective examination of mean relative telomere length in the Tasmanian Familial Hematological Malignancies Study. Oncol Rep 2014; 33:25-32. [PMID: 25351806 PMCID: PMC4254675 DOI: 10.3892/or.2014.3568] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/02/2014] [Indexed: 12/27/2022] Open
Abstract
Telomere length has a biological link to cancer, with excessive telomere shortening leading to genetic instability and resultant malignant transformation. Telomere length is heritable and genetic variants determining telomere length have been identified. Telomere biology has been implicated in the development of hematological malignancies (HMs), therefore, closer examination of telomere length in HMs may provide further insight into genetic etiology of disease development and support for telomere length as a prognostic factor in HMs. We retrospectively examined mean relative telomere length in the Tasmanian Familial Hematological Malignancies Study using a quantitative PCR method on genomic DNA from peripheral blood samples. Fifty-five familial HM cases, 191 unaffected relatives of familial HM cases and 75 non-familial HM cases were compared with 758 population controls. Variance components modeling was employed to identify factors influencing variation in telomere length. Overall, HM cases had shorter mean relative telomere length (P=2.9×10−6) and this was observed across both familial and non-familial HM cases (P=2.2×10−4 and 2.2×10−5, respectively) as well as additional subgroupings of HM cases according to broad subtypes. Mean relative telomere length was also significantly heritable (62.6%; P=4.7×10−5) in the HM families in the present study. We present new evidence of significantly shorter mean relative telomere length in both familial and non-familial HM cases from the same population adding further support to the potential use of telomere length as a prognostic factor in HMs. Whether telomere shortening is the cause of or the result of HMs is yet to be determined, but as telomere length was found to be highly heritable in our HM families this suggests that genetics driving the variation in telomere length is related to HM disease risk.
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261
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Absolute qPCR for Measuring Telomere Length in Bone Marrow Samples of Plasma Cell Disorders. Mol Biotechnol 2014; 57:155-9. [DOI: 10.1007/s12033-014-9811-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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262
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Jergović M, Tomičević M, Vidović A, Bendelja K, Savić A, Vojvoda V, Rac D, Lovrić-Čavar D, Rabatić S, Jovanovic T, Sabioncello A. Telomere shortening and immune activity in war veterans with posttraumatic stress disorder. Prog Neuropsychopharmacol Biol Psychiatry 2014; 54:275-83. [PMID: 24977331 DOI: 10.1016/j.pnpbp.2014.06.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 06/11/2014] [Accepted: 06/23/2014] [Indexed: 01/01/2023]
Abstract
BACKGROUND There is increasing evidence that chronic stress accelerates telomere erosion in leukocytes/peripheral blood mononuclear cells (PBMCs). However, functional changes associated with telomere shortening are poorly understood. We hypothesized that war veterans with PTSD would have shorter telomeres in PBMCs and that these cells might exhibit changes in measures of immune reactivity such as proliferation, cytokine production and expression of regulators of immune responses. METHODS We measured relative telomere length and basal telomerase activity in PBMCs of 62 individuals (PTSD patients (N=30); age-matched healthy controls (N=17), elderly volunteers (N=15)). In parallel, we have assessed proliferation of activated T cells, interferon (IFN)-γ, interleukin (IL)-2, IL-4, tumor necrosis factor (TNF)-α and IL-6 cytokine production and expression of programmed death 1 (PD-1) receptor and its ligand PD-L1 on activated T cells. RESULTS Middle-aged war veterans with current PTSD had shorter PBMC telomere length than their age-matched healthy controls while the elderly had the shortest telomeres. There was no difference in telomerase activity between PTSD patients and healthy controls while telomerase activity was significantly lower in the elderly. While the elderly group exhibited robust changes in immune activity such as increased production of proinflammatory cytokines (TNF-α, IL-6) and reduced proliferation of all T cells, the PTSD group showed reduced proliferative response of CD8(+) T cells to high concentrations of mitogen and reduced spontaneous production of IL-2 and IFN-γ. CONCLUSIONS This study adds to the accumulating evidence that psychological trauma and chronic stress are associated with accelerated telomere attrition. However, changes in immune function associated with stress-related telomere shortening are not well understood. Although much less pronounced in PTSD patients than in elderly persons, reduced proliferative responses of T cells accompanied by shorter telomeres might be a sign of early immunosenescence. Together with reduced production of Th1 cytokines, observed immune changes may contribute to health risks associated with PTSD.
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Affiliation(s)
- Mladen Jergović
- Centre for Research and Knowledge Transfer in Biotechnology, University of Zagreb, Zagreb, Croatia.
| | - Marko Tomičević
- Dr. Josip Benčević General Hospital, Slavonski Brod, Croatia
| | | | - Krešo Bendelja
- Centre for Research and Knowledge Transfer in Biotechnology, University of Zagreb, Zagreb, Croatia
| | - Ana Savić
- Centre for Research and Knowledge Transfer in Biotechnology, University of Zagreb, Zagreb, Croatia
| | - Valerija Vojvoda
- Centre for Research and Knowledge Transfer in Biotechnology, University of Zagreb, Zagreb, Croatia
| | - Dijana Rac
- Dr. Josip Benčević General Hospital, Slavonski Brod, Croatia
| | | | - Sabina Rabatić
- Institute of Immunology, Department for Cellular Immunology, Zagreb, Croatia
| | - Tanja Jovanovic
- Emory University, Department of Psychiatry & Behavioral Sciences, Atlanta, GA, USA
| | - Ante Sabioncello
- Institute of Immunology, Department for Cellular Immunology, Zagreb, Croatia
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263
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Wilson B, Novakofski KD, Donocoff RS, Liang YXA, Fortier LA. Telomerase Activity in Articular Chondrocytes Is Lost after Puberty. Cartilage 2014; 5:215-20. [PMID: 26069700 PMCID: PMC4335769 DOI: 10.1177/1947603514537518] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE Telomere length and telomerase activity are important indicators of cellular senescence and replicative ability. Loss of telomerase is associated with ageing and the development of osteoarthritis. Implantation of telomerase-positive cells, chondrocytes, or stem cells expressing a normal chondrocyte phenotype is desired for cartilage repair procedures. The objective of this study was to identify at what age chondrocytes and at what passage bone marrow-derived mesenchymal stem cells (MSCs) become senescent based on telomerase activity. The effect of osteogenic protein-1 (OP-1) or interleukin-1α (IL-1α) treatment on telomerase activity in chondrocytes was also measured to determine the response to anabolic or catabolic stimuli. METHODS Articular cartilage was collected from horses (n = 12) aged 1 month to 18 years. Chondrocytes from prepubescent horses (<15 months) were treated with OP-1 or IL-1α. Bone marrow aspirate from adult horses was collected and cultured for up to 10 days to isolate MSCs. Telomerase activity was measured using the TeloTAGGG Telomerase PCR ELISA kit. RESULTS Chondrocytes from prepubescent horses were positive for telomerase activity. Treatment with IL-1α resulted in a decrease in chondrocyte telomerase activity; however, treatment with OP-1 did not change telomerase activity. One MSC culture sample was positive for telomerase activity on day 2; all samples were negative for telomerase activity on day 10. CONCLUSIONS These results suggest that chondrocytes from prepubescent donors are potentially more suitable for cartilage repair procedures and that telomerase activity is diminished by anabolic and catabolic cytokine stimulation. If MSCs are utilized in cartilage repair, minimal passaging should be performed prior to implantation.
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Affiliation(s)
- Brooke Wilson
- Department of Clinical Sciences, Cornell University, Ithaca, NY, USA
| | | | | | | | - Lisa A. Fortier
- Department of Clinical Sciences, Cornell University, Ithaca, NY, USA
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264
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Inherited bone marrow failure associated with germline mutation of ACD, the gene encoding telomere protein TPP1. Blood 2014; 124:2767-74. [PMID: 25205116 DOI: 10.1182/blood-2014-08-596445] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Telomerase is a ribonucleoprotein enzyme that is necessary for overcoming telomere shortening in human germ and stem cells. Mutations in telomerase or other telomere-maintenance proteins can lead to diseases characterized by depletion of hematopoietic stem cells and bone marrow failure (BMF). Telomerase localization to telomeres requires an interaction with a region on the surface of the telomere-binding protein TPP1 known as the TEL patch. Here, we identify a family with aplastic anemia and other related hematopoietic disorders in which a 1-amino-acid deletion in the TEL patch of TPP1 (ΔK170) segregates with disease. All family members carrying this mutation, but not those with wild-type TPP1, have short telomeres. When introduced into 293T cells, TPP1 with the ΔK170 mutation is able to localize to telomeres but fails to recruit telomerase to telomeres, supporting a causal relationship between this TPP1 mutation and bone marrow disorders. ACD/TPP1 is thus a newly identified telomere-related gene in which mutations cause aplastic anemia and related BMF disorders.
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265
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Jones RE, Oh S, Grimstead JW, Zimbric J, Roger L, Heppel NH, Ashelford KE, Liddiard K, Hendrickson EA, Baird DM. Escape from telomere-driven crisis is DNA ligase III dependent. Cell Rep 2014; 8:1063-76. [PMID: 25127141 DOI: 10.1016/j.celrep.2014.07.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/28/2014] [Accepted: 07/10/2014] [Indexed: 12/27/2022] Open
Abstract
Short dysfunctional telomeres are capable of fusion, generating dicentric chromosomes and initiating breakage-fusion-bridge cycles. Cells that escape the ensuing cellular crisis exhibit large-scale genomic rearrangements that drive clonal evolution and malignant progression. We demonstrate that there is an absolute requirement for fully functional DNA ligase III (LIG3), but not ligase IV (LIG4), to facilitate the escape from a telomere-driven crisis. LIG3- and LIG4-dependent alternative (A) and classical (C) nonhomologous end-joining (NHEJ) pathways were capable of mediating the fusion of short dysfunctional telomeres, both displaying characteristic patterns of microhomology and deletion. Cells that failed to escape crisis exhibited increased proportions of C-NHEJ-mediated interchromosomal fusions, whereas those that escaped displayed increased proportions of intrachromosomal fusions. We propose that the balance between inter- and intrachromosomal telomere fusions dictates the ability of human cells to escape crisis and is influenced by the relative activities of A- and C-NHEJ at short dysfunctional telomeres.
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Affiliation(s)
- Rhiannon E Jones
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Sehyun Oh
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Julia W Grimstead
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Jacob Zimbric
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Laureline Roger
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Nicole H Heppel
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Kevin E Ashelford
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Kate Liddiard
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Duncan M Baird
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
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266
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Gobbini E, Trovesi C, Cassani C, Longhese MP. Telomere uncapping at the crossroad between cell cycle arrest and carcinogenesis. Mol Cell Oncol 2014; 1:e29901. [PMID: 27308311 PMCID: PMC4905175 DOI: 10.4161/mco.29901] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/24/2014] [Accepted: 06/30/2014] [Indexed: 01/24/2023]
Abstract
Telomeres are nucleoprotein complexes that protect the natural ends of chromosomes from fusion and degradation and prevent them eliciting a checkpoint response. This protective function, which is called telomere capping, is largely mediated by telomere-binding proteins that suppress checkpoint activation and DNA repair activities. Telomere dysfunction through progressive shortening or removal of capping proteins leads to a checkpoint-mediated block of cell proliferation, which acts as a cancer-suppressor mechanism. However, genetic alterations that inactivate the checkpoint can lead to further telomere erosion and increased genomic instability that, coupled with the activation of mechanisms to restabilize telomeres, can drive the oncogenic process.
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Affiliation(s)
- Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze; Università degli Studi di Milano-Bicocca; Milano, Italia
| | - Camilla Trovesi
- Dipartimento di Biotecnologie e Bioscienze; Università degli Studi di Milano-Bicocca; Milano, Italia
| | - Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze; Università degli Studi di Milano-Bicocca; Milano, Italia
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze; Università degli Studi di Milano-Bicocca; Milano, Italia
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267
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Harley CB, Liu W, Flom PL, Raffaele JM. A natural product telomerase activator as part of a health maintenance program: metabolic and cardiovascular response. Rejuvenation Res 2014; 16:386-95. [PMID: 23808324 DOI: 10.1089/rej.2013.1430] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A short average telomere length is associated with low telomerase activity and certain degenerative diseases. Studies in animals and with human cells confirm a causal mechanism for cell or tissue dysfunction triggered by critically short telomeres, suggesting that telomerase activation may be an approach to health maintenance. Previously, we reported on positive immune remodeling in humans taking a commercial health maintenance program, PattonProtocol-1, composed of TA-65® (a natural product-derived telomerase activator) and other dietary supplements. In over a 5-year period and an estimated 7000 person-years of use, no adverse events or effects have been attributed to TA-65 by physicians licensed to sell the product. Here we report on changes in metabolic markers measured at baseline (n=97-107 subjects) and every 3-6 months (n=27-59 subjects) during the first 12 months of study. Rates of change per year from baseline determined by a multi-level model were -3.72 mg/dL for fasting glucose (p=0.02), -1.32 mIU/mL for insulin (p=0.01), -13.2 and -11.8 mg/dL for total cholesterol and low-density lipoprotein cholesterol (LDL-C) (p=0.002, p=0.002, respectively), -17.3 and -4.2 mmHg for systolic and diastolic blood pressure (p=0.007 and 0.001, respectively), and -3.6 μmole/L homocysteine (p=0.001). In a subset of individuals with bone mineral density (BMD) measured at baseline and 12 months, density increased 2.0% in the spine (p=0.003). We conclude that in addition to apparent positive immune remodeling, PattonProtocol-1 may improve markers of metabolic, bone, and cardiovascular health.
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268
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Li JR, Yu TY, Chien IC, Lu CY, Lin JJ, Li HW. Pif1 regulates telomere length by preferentially removing telomerase from long telomere ends. Nucleic Acids Res 2014; 42:8527-36. [PMID: 24981509 PMCID: PMC4117769 DOI: 10.1093/nar/gku541] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Telomerase, a ribonucleoprotein complex, is responsible for maintaining the telomere length at chromosome ends. Using its RNA component as a template, telomerase uses its reverse transcriptase activity to extend the 3'-end single-stranded, repetitive telomeric DNA sequence. Pif1, a 5'-to-3' helicase, has been suggested to regulate telomerase activity. We used single-molecule experiments to directly show that Pif1 helicase regulates telomerase activity by removing telomerase from telomere ends, allowing the cycling of the telomerase for additional extension processes. This telomerase removal efficiency increases at longer ssDNA gaps and at higher Pif1 concentrations. The enhanced telomerase removal efficiency by Pif1 at the longer single-stranded telomeric DNA suggests a way of how Pif1 regulates telomerase activity and maintains telomere length.
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Affiliation(s)
- Jing-Ru Li
- Department of Chemistry, National Taiwan University, Taiwan
| | - Tai-Yuan Yu
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taiwan
| | - I-Chieh Chien
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taiwan
| | - Chia-Ying Lu
- Institute of Biochemistry and Molecular Biology, National Taiwan University, Taiwan
| | - Jing-Jer Lin
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taiwan Institute of Biochemistry and Molecular Biology, National Taiwan University, Taiwan Institute of Biochemistry and Molecular Biology, National Taiwan University, Taiwan
| | - Hung-Wen Li
- Department of Chemistry, National Taiwan University, Taiwan
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269
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The 58-kda microspherule protein (MSP58) represses human telomerase reverse transcriptase (hTERT) gene expression and cell proliferation by interacting with telomerase transcriptional element-interacting factor (TEIF). BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:565-79. [PMID: 24361335 DOI: 10.1016/j.bbamcr.2013.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 11/13/2013] [Accepted: 12/04/2013] [Indexed: 11/21/2022]
Abstract
58-kDa microspherule protein (MSP58) plays an important role in a variety of cellular processes including transcriptional regulation, cell proliferation and oncogenic transformation. Currently, the mechanisms underlying the oncogenic effect of MSP58 are not fully understood. The human telomerase reverse transcriptase (hTERT) gene, which encodes an essential component for telomerase activity that is involved in cellular immortalization and transformation, is strictly regulated at the gene transcription level. Our previous study revealed a novel function of MSP58 in cellular senescence. Here we identify telomerase transcriptional element-interacting factor (TEIF) as a novel MSP58-interacting protein and determine the effect of MSP58 on hTERT transcription. This study thus provides evidence showing MSP58 to be a negative regulator of hTERT expression and telomerase activity. Luciferase reporter assays indicated that MSP58 could suppress the transcription ofhTERTpromoter. Additionally, stable overexpression of MSP58 protein in HT1080 and 293T cells decreased both endogenous hTERT expression and telomerase activity. Conversely, their upregulation was induced by MSP58 silencing. Chromatin immunoprecipitation assays showed that MSP58 binds to the hTERT proximal promoter. Furthermore, overexpression of MSP58 inhibited TEIF-mediated hTERT transactivation, telomerase activation, and cell proliferation promotion. The inhibitory effect of MSP58 occurred through inhibition of TEIF binding to DNA. Ultimately, the HT1080-implanted xenograft mouse model confirmed these cellular effects. Together, our findings provide new insights into both the biological function of MSP58 and the regulation of telomerase/hTERT expression.
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270
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Synthetic Approach to Telomerase Inhibitor Dictyodendrin B: Synthesis of the Pyrrolo[2,3-c]carbazole Core. Biosci Biotechnol Biochem 2014; 73:1764-72. [DOI: 10.1271/bbb.90111] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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271
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Wang S, Chen X, Tang M. Quantitative assessment of the diagnostic role of human telomerase activity from pancreatic juice in pancreatic cancer. Tumour Biol 2014; 35:7897-904. [DOI: 10.1007/s13277-014-2053-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 05/05/2014] [Indexed: 01/06/2023] Open
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272
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Mania A, Mantzouratou A, Delhanty JD, Baio G, Serhal P, Sengupta SB. Telomere length in human blastocysts. Reprod Biomed Online 2014; 28:624-37. [DOI: 10.1016/j.rbmo.2013.12.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 12/10/2013] [Accepted: 12/18/2013] [Indexed: 11/27/2022]
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273
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Rajavel M, Mullins MR, Taylor DJ. Multiple facets of TPP1 in telomere maintenance. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1550-9. [PMID: 24780581 DOI: 10.1016/j.bbapap.2014.04.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 04/01/2014] [Accepted: 04/18/2014] [Indexed: 11/30/2022]
Abstract
Telomeres are nucleoprotein complexes that cap the ends of all linear chromosomes and function to prevent aberrant repair and end-to-end chromosome fusions. In somatic cells, telomere shortening is a natural part of the aging process as it occurs with each round of cell division. In germ and stem cells, however, the enzyme telomerase synthesizes telomere DNA to counter-balance telomere shortening and help maintain cellular proliferation. Of the primary telomere end-binding proteins, TPP1 has recently emerged as a primary contributor in protecting telomere DNA and in recruiting telomerase to the telomere ends. In this review, we summarize the current knowledge regarding the role of TPP1 in telomere maintenance.
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Affiliation(s)
- Malligarjunan Rajavel
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland OH 44106, USA
| | - Michael R Mullins
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland OH 44106, USA
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland OH 44106, USA; Department of Biochemistry, Case Western Reserve University, School of Medicine, Cleveland OH 44106, USA.
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274
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Longer telomere length in COPD patients with α1-antitrypsin deficiency independent of lung function. PLoS One 2014; 9:e95600. [PMID: 24763308 PMCID: PMC3998943 DOI: 10.1371/journal.pone.0095600] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 03/28/2014] [Indexed: 01/22/2023] Open
Abstract
Oxidative stress is involved in the pathogenesis of airway obstruction in α1-antitrypsin deficient patients. This may result in a shortening of telomere length, resulting in cellular senescence. To test whether telomere length differs in α1-antitrypsin deficient patients compared with controls, we measured telomere length in DNA from peripheral blood cells of 217 α1-antitrypsin deficient patients and 217 control COPD patients. We also tested for differences in telomere length between DNA from blood and DNA from lung tissue in a subset of 51 controls. We found that telomere length in the blood was significantly longer in α1-antitrypsin deficient COPD patients compared with control COPD patients (p = 1×10−29). Telomere length was not related to lung function in α1-antitrypsin deficient patients (p = 0.3122) or in COPD controls (p = 0.1430). Although mean telomere length was significantly shorter in the blood when compared with the lungs (p = 0.0078), telomere length was correlated between the two tissue types (p = 0.0122). Our results indicate that telomere length is better preserved in α1-antitrypsin deficient COPD patients than in non-deficient patients. In addition, measurement of telomere length in the blood may be a suitable surrogate for measurement in the lung.
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275
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Wen VW, MacKenzie KL. Modeling human endothelial cell transformation in vascular neoplasias. Dis Model Mech 2014; 6:1066-79. [PMID: 24046386 PMCID: PMC3759327 DOI: 10.1242/dmm.012674] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Endothelial cell (EC)-derived neoplasias range from benign hemangioma to aggressive metastatic angiosarcoma, which responds poorly to current treatments and has a very high mortality rate. The development of treatments that are more effective for these disorders will be expedited by insight into the processes that promote abnormal proliferation and malignant transformation of human ECs. The study of primary endothelial malignancy has been limited by the rarity of the disease; however, there is potential for carefully characterized EC lines and animal models to play a central role in the discovery, development and testing of molecular targeted therapies for vascular neoplasias. This review describes molecular alterations that have been identified in EC-derived neoplasias, as well as the processes that underpin the immortalization and tumorigenic conversion of ECs. Human EC lines, established through the introduction of defined genetic elements or by culture of primary tumor tissue, are catalogued and discussed in relation to their relevance as models of vascular neoplasia.
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Affiliation(s)
- Victoria W Wen
- Cancer Cell Development Group, Children's Cancer Institute Australia for Medical Research, Lowy Cancer Research Centre, University of New South Wales, Randwick, NSW, Australia
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276
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Zheng YL, Zhang F, Sun B, Du J, Sun C, Yuan J, Wang Y, Tao L, Kota K, Liu X, Schlegel R, Yang Q. Telomerase enzymatic component hTERT shortens long telomeres in human cells. Cell Cycle 2014; 13:1765-76. [PMID: 24721976 DOI: 10.4161/cc.28705] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Telomere lengths are tightly regulated within a narrow range in normal human cells. Previous studies have extensively focused on how short telomeres are extended and have demonstrated that telomerase plays a central role in elongating short telomeres. However, much about the molecular mechanisms of regulating excessively long telomeres is unknown. In this report, we demonstrated that the telomerase enzymatic component, hTERT, plays a dual role in the regulation of telomere length. It shortens excessively long telomeres and elongates short telomeres simultaneously in one cell, maintaining the optimal telomere length at each chromosomal end for efficient protection. This novel hTERT-mediated telomere-shortening mechanism not only exists in cancer cells, but also in primary human cells. The hTERT-mediated telomere shortening requires hTERT's enzymatic activity, but the telomerase RNA component, hTR, is not involved in that process. We found that expression of hTERT increases telomeric circular DNA formation, suggesting that telomere homologous recombination is involved in the telomere-shortening process. We further demonstrated that shelterin protein TPP1 interacts with hTERT and recruits hTERT onto the telomeres, suggesting that TPP1 might be involved in regulation of telomere shortening. This study reveals a novel function of hTERT in telomere length regulation and adds a new element to the current molecular model of telomere length maintenance.
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Affiliation(s)
- Yun-Ling Zheng
- Cancer Prevention and Control; Lombardi Comprehensive Cancer Center; Georgetown University Medical Center; Washington, DC USA
| | - Fan Zhang
- Cancer Biology Division; Washington University School of Medicine; Saint Louis, MO USA
| | - Bing Sun
- Cancer Prevention and Control; Lombardi Comprehensive Cancer Center; Georgetown University Medical Center; Washington, DC USA
| | - Juan Du
- Cancer Biology Division; Washington University School of Medicine; Saint Louis, MO USA
| | - Chongkui Sun
- Cancer Biology Division; Washington University School of Medicine; Saint Louis, MO USA
| | - Jie Yuan
- Medical College; Jinan University; Guangzhou, China
| | - Ying Wang
- Cancer Prevention and Control; Lombardi Comprehensive Cancer Center; Georgetown University Medical Center; Washington, DC USA
| | - Lian Tao
- Cancer Prevention and Control; Lombardi Comprehensive Cancer Center; Georgetown University Medical Center; Washington, DC USA
| | - Krishna Kota
- Cancer Prevention and Control; Lombardi Comprehensive Cancer Center; Georgetown University Medical Center; Washington, DC USA
| | - Xuefeng Liu
- Molecular Oncology Programs; Lombardi Comprehensive Cancer Center; Georgetown University Medical Center; Washington, DC USA
| | - Richard Schlegel
- Molecular Oncology Programs; Lombardi Comprehensive Cancer Center; Georgetown University Medical Center; Washington, DC USA
| | - Qin Yang
- Cancer Biology Division; Washington University School of Medicine; Saint Louis, MO USA
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277
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Hoxha M, Fabris S, Agnelli L, Bollati V, Cutrona G, Matis S, Recchia AG, Gentile M, Cortelezzi A, Morabito F, Bertazzi PA, Ferrarini M, Neri A. Relevance of telomere/telomerase system impairment in early stage chronic lymphocytic leukemia. Genes Chromosomes Cancer 2014; 53:612-21. [PMID: 24706380 DOI: 10.1002/gcc.22171] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 03/18/2014] [Indexed: 01/10/2023] Open
Abstract
Several studies have proposed telomere length and telomerase activity as prognostic factors in chronic lymphocytic leukemia (CLL), whereas information addressing the role of telomere-associated genes is limited. We measured relative telomere length (RTL) and TERT expression levels in purified peripheral CD19(+) B-cells from seven healthy donors and 77 untreated CLLs in early stage disease (Binet A). Data were correlated with the major biological and cytogenetic markers, global DNA methylation (Alu and LINE-1), and clinical outcome. The expression profiles of telomere-associated genes were also investigated. RTL was decreased in CLLs as compared with controls (P < 0.001); within CLL, a progressive and significant RTL shortening was observed in patients from 13q- through +12, 11q-, and 17p- alterations; short telomeres were significantly associated with unmutated IGHV configuration and global DNA hypomethylation. Decreased RTL was associated with a shorter time to first treatment. A significant upregulation of POT1, TRF1, RAP1, MRE11A, RAD50, and RPA1 transcript levels was observed in CLLs compared with controls. Our study suggests that impairment of telomere/telomerase system represents an early event in CLL pathogenesis. Moreover, the correlation between telomere shortening and global DNA hypomethylation supports the involvement of DNA hypomethylation to increase chromosome instability. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Mirjam Hoxha
- Department of Clinical Sciences and Community Health, Center of Molecular and Genetic Epidemiology, University of Milan, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
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278
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Donai K, Kiyono T, Eitsuka T, Guo Y, Kuroda K, Sone H, Isogai E, Fukuda T. Bovine and porcine fibroblasts can be immortalized with intact karyotype by the expression of mutant cyclin dependent kinase 4, cyclin D, and telomerase. J Biotechnol 2014; 176:50-7. [PMID: 24589663 DOI: 10.1016/j.jbiotec.2014.02.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 02/14/2014] [Accepted: 02/19/2014] [Indexed: 01/13/2023]
Abstract
Cattle and pigs comprise the most economically important livestock. Despite their importance, cultured cells from these species, which are useful for physiological analyses, are quite limited in cell banks. One of the reasons for the limited number of cell lines is the difficulty in their establishment. To overcome limitations in cell-line establishment, we attempted to immortalize bovine and porcine fibroblasts by transduction of multiple cell cycle regulators (mutant cyclin dependent kinase 4, cyclin D and telomerase reverse transcriptase). The transduced cells continued to display a stable proliferation rate and did not show cellular senescence. Furthermore, cell cycle assays showed that induction of these exogenous genes enhanced turnover of the cell cycle, especially at the G1-S phase. Furthermore, our established cell lines maintained normal diploid karyotypes at 98-100%. Our study demonstrated that bypassing p16/Rb-mediated cell arrest and activation of telomerase activity enabled efficient establishment of immortalized bovine- and porcine-derived fibroblasts. The high efficiency of establishing cell lines suggests that the networks of cell cycle regulators, especially p16/Rb-associated cell cycle arrest, have been conserved during evolution of humans, cattle, and pigs.
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Affiliation(s)
- Kenichiro Donai
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
| | - Tohru Kiyono
- Division of Virology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
| | - Takahiro Eitsuka
- Faculty of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, 265-1, Higashijima, Akiha-ku, Niigata 956-8603, Japan.
| | - Yijie Guo
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
| | - Kengo Kuroda
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
| | - Hideko Sone
- Environmental Exposure Research Section, Center for Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
| | - Emiko Isogai
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
| | - Tomokazu Fukuda
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
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279
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Alternative lengthening of telomeres in cancer stem cells in vivo. Oncogene 2014; 34:611-20. [PMID: 24531712 PMCID: PMC4135038 DOI: 10.1038/onc.2013.603] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 11/01/2013] [Accepted: 12/18/2013] [Indexed: 12/17/2022]
Abstract
Chromosome ends are protected by telomeres which prevent DNA damage response and degradation. Telomerase expression extends telomeres and inhibits DNA damage response. Telomeres are also maintained by the recombination based alternative lengthening pathway. Telomerase is believed to be the sole mechanism for telomere maintenance in epidermis. We show that basal cells in epidermis maintain telomeres both by telomerase and ALT mechanisms in vivo. ALT was detected in epidermal stem cells in Terc−/− mice, and normal human epidermal keratinocytes are also ALT positive. ALT pathway is suppressed in primary but not metastatic epidermal squamous cell carcinomas (SCC) in Terc+/+ mice. ALT pathway is expressed in stem and basal cells in epidermal SCC in Terc−/− mice, and some telomerase positive human SCC lines. Telomeres shorten dramatically in stem and basal cells in epidermal SCC in vivo. Telomere shortening is associated with telomeric DNA damage response and apoptosis in stem and basal cells. Stem cells were transformed in both primary and metastatic epidermal SCC. Genetic ablation of this small cell population resulted in significant tumor regression in vivo. We concluded that alternative lengthening of telomeres is important in epidermal homeostasis and tumorigenesis in vivo.
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280
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Díaz de la Guardia R, Catalina P, Panero J, Elosua C, Pulgarin A, López MB, Ayllón V, Ligero G, Slavutsky I, Leone PE. Expression profile of telomere-associated genes in multiple myeloma. J Cell Mol Med 2014; 16:3009-21. [PMID: 22947336 PMCID: PMC4393729 DOI: 10.1111/j.1582-4934.2012.01628.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 08/14/2012] [Indexed: 12/31/2022] Open
Abstract
To further contribute to the understanding of multiple myeloma, we have focused our research interests on the mechanisms by which tumour plasma cells have a higher survival rate than normal plasma cells. In this article, we study the expression profile of genes involved in the regulation and protection of telomere length, telomerase activity and apoptosis in samples from patients with monoclonal gammopathy of undetermined significance, smouldering multiple myeloma, multiple myeloma (MM) and plasma cell leukaemia (PCL), as well as several human myeloma cell lines (HMCLs). Using conventional cytogenetic and fluorescence in situ hybridization studies, we identified a high number of telomeric associations (TAs). Moreover, telomere length measurements by terminal restriction fragment (TRF) assay showed a shorter mean TRF peak value, with a consistent correlation with the number of TAs. Using gene expression arrays and quantitative PCR we identified the hTERT gene together with 16 other genes directly involved in telomere length maintenance: HSPA9, KRAS, RB1, members of the Small nucleolar ribonucleoproteins family, A/B subfamily of ubiquitously expressed heterogeneous nuclear ribonucleoproteins, and 14-3-3 family. The expression levels of these genes were even higher than those in human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), which have unlimited proliferation capacity. In conclusion, the gene signature suggests that MM tumour cells are able to maintain stable short telomere lengths without exceeding the short critical length, allowing cell divisions to continue. We propose that this could be a mechanism contributing to MM tumour cells expansion in the bone marrow (BM).
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Affiliation(s)
- Rafael Díaz de la Guardia
- Andalusian Public Health System Biobank, Centro de Investigación Biomédica, Consejería de Salud-Universidad de Granada, Granada, Spain.
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281
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Shim G, Ricoul M, Hempel WM, Azzam EI, Sabatier L. Crosstalk between telomere maintenance and radiation effects: A key player in the process of radiation-induced carcinogenesis. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2014; 760:S1383-5742(14)00002-7. [PMID: 24486376 PMCID: PMC4119099 DOI: 10.1016/j.mrrev.2014.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 01/14/2014] [Accepted: 01/22/2014] [Indexed: 02/06/2023]
Abstract
It is well established that ionizing radiation induces chromosomal damage, both following direct radiation exposure and via non-targeted (bystander) effects, activating DNA damage repair pathways, of which the proteins are closely linked to telomeric proteins and telomere maintenance. Long-term propagation of this radiation-induced chromosomal damage during cell proliferation results in chromosomal instability. Many studies have shown the link between radiation exposure and radiation-induced changes in oxidative stress and DNA damage repair in both targeted and non-targeted cells. However, the effect of these factors on telomeres, long established as guardians of the genome, still remains to be clarified. In this review, we will focus on what is known about how telomeres are affected by exposure to low- and high-LET ionizing radiation and during proliferation, and will discuss how telomeres may be a key player in the process of radiation-induced carcinogenesis.
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282
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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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283
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Aubert G. Telomere Dynamics and Aging. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 125:89-111. [DOI: 10.1016/b978-0-12-397898-1.00004-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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284
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Funayama R, Nakahara Y, Kado S, Tanaka M, Kimura K. A single-molecule force-spectroscopic study on stabilization of G-quadruplex DNA by a telomerase inhibitor. Analyst 2014; 139:4037-43. [DOI: 10.1039/c4an00439f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The stabilization of G-quadruplex DNA by a telomerase inhibitor was semi-quantitatively evaluated by AFM-based SMFS.
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Affiliation(s)
- Ryoto Funayama
- Department of Applied Chemistry
- Faculty of Systems Engineering
- Wakayama University
- Wakayama 640-8510, Japan
| | - Yoshio Nakahara
- Department of Applied Chemistry
- Faculty of Systems Engineering
- Wakayama University
- Wakayama 640-8510, Japan
| | - Shinpei Kado
- Department of Applied Chemistry
- Faculty of Systems Engineering
- Wakayama University
- Wakayama 640-8510, Japan
| | - Mutsuo Tanaka
- National Institute of Advanced Industrial Science and Technology
- Tsukuba, Japan
| | - Keiichi Kimura
- Department of Applied Chemistry
- Faculty of Systems Engineering
- Wakayama University
- Wakayama 640-8510, Japan
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285
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Abstract
Telomeres are the physical ends of eukaryotic linear chromosomes. Telomeres form special structures that cap chromosome ends to prevent degradation by nucleolytic attack and to distinguish chromosome termini from DNA double-strand breaks. With few exceptions, telomeres are composed primarily of repetitive DNA associated with proteins that interact specifically with double- or single-stranded telomeric DNA or with each other, forming highly ordered and dynamic complexes involved in telomere maintenance and length regulation. In proliferative cells and unicellular organisms, telomeric DNA is replicated by the actions of telomerase, a specialized reverse transcriptase. In the absence of telomerase, some cells employ a recombination-based DNA replication pathway known as alternative lengthening of telomeres. However, mammalian somatic cells that naturally lack telomerase activity show telomere shortening with increasing age leading to cell cycle arrest and senescence. In another way, mutations or deletions of telomerase components can lead to inherited genetic disorders, and the depletion of telomeric proteins can elicit the action of distinct kinases-dependent DNA damage response, culminating in chromosomal abnormalities that are incompatible with life. In addition to the intricate network formed by the interrelationships among telomeric proteins, long noncoding RNAs that arise from subtelomeric regions, named telomeric repeat-containing RNA, are also implicated in telomerase regulation and telomere maintenance. The goal for the next years is to increase our knowledge about the mechanisms that regulate telomere homeostasis and the means by which their absence or defect can elicit telomere dysfunction, which generally results in gross genomic instability and genetic diseases.
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286
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TGF-β signaling in stem cells and tumorigenesis. Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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287
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Mason PJ, Perdigones N. Telomere biology and translational research. Transl Res 2013; 162:333-42. [PMID: 24070997 PMCID: PMC4021592 DOI: 10.1016/j.trsl.2013.08.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 08/30/2013] [Indexed: 12/27/2022]
Affiliation(s)
- Philip J Mason
- Division of Hematology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA.
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288
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Pal J, Gold JS, Munshi NC, Shammas MA. Biology of telomeres: importance in etiology of esophageal cancer and as therapeutic target. Transl Res 2013; 162:364-70. [PMID: 24090770 PMCID: PMC3834232 DOI: 10.1016/j.trsl.2013.09.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 09/05/2013] [Accepted: 09/06/2013] [Indexed: 11/17/2022]
Abstract
The purpose of this review is to highlight the importance of telomeres, the mechanisms implicated in their maintenance, and their role in the etiology as well as the treatment of human esophageal cancer. We will also discuss the role of telomeres in the maintenance and preservation of genomic integrity, the consequences of telomere dysfunction, and the various factors that may affect telomere health in esophageal tissue predisposing it to oncogenesis. There has been growing evidence that telomeres, which can be affected by various intrinsic and extrinsic factors, contribute to genomic instability, oncogenesis, as well as proliferation of cancer cells. Telomeres are the protective DNA-protein complexes at chromosome ends. Telomeric DNA undergoes progressive shortening with age leading to cellular senescence and/or apoptosis. If senescence/apoptosis is prevented as a consequence of specific genomic changes, continued proliferation leads to very short (ie, dysfunctional) telomeres that can potentially cause genomic instability, thus, increasing the risk for activation of telomere maintenance mechanisms and oncogenesis. Like many other cancers, esophageal cancer cells have short telomeres and elevated telomerase, the enzyme that maintains telomeres in most cancer cells. Homologous recombination, which is implicated in the alternate pathway of telomere elongation, is also elevated in Barrett's-associated esophageal adenocarcinoma. Evidence from our laboratory indicates that both telomerase and homologous recombination contribute to telomere maintenance, DNA repair, and the ongoing survival of esophageal cancer cells. This indicates that telomere maintenance mechanisms may potentially be targeted to make esophageal cancer cells static. The rate at which telomeres in healthy cells shorten is determined by a number of intrinsic and extrinsic factors, including those associated with lifestyle. Avoidance of factors that may directly or indirectly injure esophageal tissue including its telomeric and other genomic DNA can not only reduce the risk of development of esophageal cancer but may also have positive impact on overall health and lifespan.
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Affiliation(s)
- Jagannath Pal
- Harvard (Dana Farber) Cancer Institute, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
| | - Jason S. Gold
- Harvard (Dana Farber) Cancer Institute, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Brigham and Women’s Hospital, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
| | - Nikhil C. Munshi
- Harvard (Dana Farber) Cancer Institute, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
| | - Masood A. Shammas
- Harvard (Dana Farber) Cancer Institute, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
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289
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Wei Y, Liu R, Sun Z, Wang Y, Cui Y, Zhao Y, Cai Z, Gao X. Luminescent silver nanoclusters anchored by oligonucleotides detect human telomerase ribonucleic acid template. Analyst 2013; 138:1338-41. [PMID: 23338699 DOI: 10.1039/c3an36689h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Luminescent silver nanoclusters were anchored by designed oligonucleotides. After hybridizing with human telomerase RNA template, the luminescence of the cluster decreased linearly with respect to the concentration of the complementary strand (25-250 nM). The cluster is therefore a potential candidate for human telomerase detection.
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Affiliation(s)
- Yueteng Wei
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic China
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290
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Abstract
Telomeres are the tips of chromosomes and consist of proteins and hexanucleotide tandem repeats of DNA. The DNA repeats are shortened at each mitotic division of normal cells, and the telomere length chronicles how many divisions the cell has undergone. Thus, telomere length is a marker of fundamental biological pathways. It has been possible to measure telomere length for more than 20 years, and it has been established that telomere length is associated with age, sex and lifestyle factors. Here, the current knowledge of telomere length as a biomarker of disease susceptibility and mortality will be reviewed. In addition, technical difficulties and the reasons why measurement of telomeres has still not been introduced into routine clinical practice will be discussed. Findings from recent studies conducted in many thousands of individuals indicate that telomere length is not-or at best only marginally-independently associated with risk of common disorders such as cardiovascular, pulmonary and neoplastic diseases. However, in sufficiently powered studies, short telomeres are repeatedly and independently found to be associated with increased risk of early death in the general population or in subsets of individuals. This indicates that measurement of telomeres could be a valuable prognostic biomarker in many clinical settings. However, whether short telomeres are a causal factor for or simply a marker of increased risk of early death must be determined. Finally, how Mendelian randomization studies could clarify this issue, and which clinical studies might be carried out to refine this very promising biomarker for routine clinical use will be considered.
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Affiliation(s)
- S E Bojesen
- Department of Clinical Biochemistry, Herlev Hospital, Copenhagen University Hospital, Herlev, Denmark; The Copenhagen General Population Study, Herlev Hospital, Copenhagen University Hospital, Herlev, Denmark; The Copenhagen City Heart Study, Frederiksberg Hospital, Copenhagen University Hospital, Herlev, Denmark; Faculty of Health Sciences, University of Copenhagen, Herlev, Denmark
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291
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Bollmann FM. Physiological and pathological significance of human telomerase reverse transcriptase splice variants. Biochimie 2013; 95:1965-70. [DOI: 10.1016/j.biochi.2013.07.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 07/29/2013] [Indexed: 12/22/2022]
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292
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Ikeda H, Aida J, Hatamochi A, Hamasaki Y, Izumiyama-Shimomura N, Nakamura KI, Ishikawa N, Poon SS, Fujiwara M, Tomita KI, Hiraishi N, Kuroiwa M, Matsuura M, Sanada Y, Kawano Y, Arai T, Takubo K. Quantitative fluorescence in situ hybridization measurement of telomere length in skin with/without sun exposure or actinic keratosis. Hum Pathol 2013; 45:473-80. [PMID: 24411948 DOI: 10.1016/j.humpath.2013.10.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/02/2013] [Accepted: 10/04/2013] [Indexed: 11/28/2022]
Abstract
Chromosomal and genomic instability due to telomere dysfunction is known to play an important role in carcinogenesis. To study telomere shortening in the epidermis surrounding actinic keratosis, we measured telomere lengths of basal, parabasal, and suprabasal cells in epidermis with actinic keratosis (actinic keratosis group, n = 18) and without actinic keratosis (sun-protected, n = 15, and sun-exposed, n = 13 groups) and in actinic keratosis itself as well as in dermal fibroblasts in the 3 groups, using quantitative fluorescence in situ hybridization. Among the 3 cell types, telomeres of basal cells were not always the longest, suggesting that tissue stem cells are not necessarily located among basal cells. Telomeres of basal cells in the sun-exposed group were shorter than those in the sun-protected group. Telomeres in the background of actinic keratosis and in actinic keratosis itself and those of fibroblasts in actinic keratosis were significantly shorter than those in the controls. Our findings demonstrate that sun exposure induces telomere shortening and that actinic keratosis arises from epidermis with shorter telomeres despite the absence of any histologic atypia.
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Affiliation(s)
- Hiroyuki Ikeda
- Research Team for Geriatric Pathology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan; Department of Dermatology, Dokkyo Medical University, School of Medicine, Mibu, Tochigi 321-0293, Japan
| | - Junko Aida
- Research Team for Geriatric Pathology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan; Department of Pathology, Tokyo Metropolitan Geriatric Hospital, Tokyo 173-0015, Japan.
| | - Atsushi Hatamochi
- Department of Dermatology, Dokkyo Medical University, School of Medicine, Mibu, Tochigi 321-0293, Japan
| | - Yoichiro Hamasaki
- Department of Dermatology, Dokkyo Medical University, School of Medicine, Mibu, Tochigi 321-0293, Japan
| | | | - Ken-Ichi Nakamura
- Research Team for Geriatric Pathology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan
| | - Naoshi Ishikawa
- Research Team for Geriatric Pathology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan
| | - Steven S Poon
- Research Team for Geriatric Pathology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan
| | - Mutsunori Fujiwara
- Department of Pathology and Laboratory Medicine, Japanese Red Cross Medical Center, Tokyo 150-8935, Japan
| | - Ken-Ichiro Tomita
- Department of Pathology and Laboratory Medicine, Japanese Red Cross Medical Center, Tokyo 150-8935, Japan
| | - Naoki Hiraishi
- Department of Laboratory Medicine, Hadano Red Cross Hospital, Hadano, Kanagawa 257-0017, Japan
| | - Mie Kuroiwa
- Department of Analytical Chemistry, Yokohama College of Pharmacy, Yokohama 245-0066, Japan
| | - Masaaki Matsuura
- Department of Cancer Genomics, The Cancer Institute, The Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Yukihiro Sanada
- Department of Transplant Surgery, Jichi Medical University, Yakushiji, Shimotsuke City, Tochigi 329-0498, Japan
| | - Youichi Kawano
- Department of Surgery, Nippon Medical School, Tokyo 113-8603, Japan
| | - Tomio Arai
- Research Team for Geriatric Pathology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan; Department of Pathology, Tokyo Metropolitan Geriatric Hospital, Tokyo 173-0015, Japan
| | - Kaiyo Takubo
- Research Team for Geriatric Pathology, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan; Department of Pathology, Tokyo Metropolitan Geriatric Hospital, Tokyo 173-0015, Japan.
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293
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Shalaby T, Fiaschetti G, Nagasawa K, Shin-ya K, Baumgartner M, Grotzer M. G-quadruplexes as potential therapeutic targets for embryonal tumors. Molecules 2013; 18:12500-37. [PMID: 24152672 PMCID: PMC6269990 DOI: 10.3390/molecules181012500] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 09/18/2013] [Accepted: 09/25/2013] [Indexed: 12/27/2022] Open
Abstract
Embryonal tumors include a heterogeneous group of highly malignant neoplasms that primarily affect infants and children and are characterized by a high rate of mortality and treatment-related morbidity, hence improved therapies are clearly needed. G-quadruplexes are special secondary structures adopted in guanine (G)-rich DNA sequences that are often present in biologically important regions, e.g. at the end of telomeres and in the regulatory regions of oncogenes such as MYC. Owing to the significant roles that both telomeres and MYC play in cancer cell biology, G-quadruplexes have been viewed as emerging therapeutic targets in oncology and as tools for novel anticancer drug design. Several compounds that target these structures have shown promising anticancer activity in tumor xenograft models and some of them have entered Phase II clinical trials. In this review we examine approaches to DNA targeted cancer therapy, summarize the recent developments of G-quadruplex ligands as anticancer drugs and speculate on the future direction of such structures as a potential novel therapeutic strategy for embryonal tumors of the nervous system.
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Affiliation(s)
- Tarek Shalaby
- Division of Oncology, University Children's Hospital of Zurich, Zurich 8032, Switzerland.
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294
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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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295
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Telomerase and its extracurricular activities. Cell Mol Biol Lett 2013; 18:538-54. [PMID: 24048710 PMCID: PMC6275585 DOI: 10.2478/s11658-013-0105-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 09/11/2013] [Indexed: 11/20/2022] Open
Abstract
The classical activity of telomerase is to synthesize telomeric repeats and thus maintain telomere length, which in turn ensures chromosome stability and cellular proliferation. However, there is growing evidence that implicates telomerase in many other functions that are independent of TERC being used as its template. Telomerase has an RNA-dependent RNA polymerase (RdRP) activity in the mitochondria. Other than viral RdRPs, it is the only RNA-dependent RNA polymerase that has been identified in mammals. It also plays a role in the Wnt signaling pathway by acting as a transcriptional modulator. Telomerase acts as a reverse transcriptase independent of its core subunit, TERC. Studies indicate that telomerase is also involved in apoptosis and DNA repair.
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296
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Takahama K, Takada A, Tada S, Shimizu M, Sayama K, Kurokawa R, Oyoshi T. Regulation of telomere length by G-quadruplex telomere DNA- and TERRA-binding protein TLS/FUS. ACTA ACUST UNITED AC 2013; 20:341-50. [PMID: 23521792 DOI: 10.1016/j.chembiol.2013.02.013] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 12/31/2022]
Abstract
Mammalian telomeres comprise noncoding TTAGGG repeats in double-stranded regions with a single-stranded TTAGGG repeat 3' overhang and are bound by a multiprotein complex with a telomeric repeat-containing RNA (TERRA) containing a UUAGGG repeat as a G-quadruplex noncoding RNA. TLS/FUS is a human telomere-binding protein that was first identified as an oncogenic fusion protein in human myxoid and round-cell liposarcoma. Here, we show that the Arg-Gly-Gly domain in the C-terminal region of TLS forms a ternary complex with human telomere G-quadruplex DNA and TERRA in vitro. Furthermore, TLS binds to G-quadruplex telomere DNA in double-stranded regions and to G-quadruplex TERRA, which regulates histone modifications of telomeres and telomere length in vivo. Our findings suggest that the G-quadruplex functions as a scaffold for the telomere-binding protein, TLS, to regulate telomere length by histone modifications.
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Affiliation(s)
- Kentaro Takahama
- Faculty of Science, Department of Chemistry, Shizuoka University, 836 Ohya Suruga, Shizuoka 422-8529, Japan
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297
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Lim KW, Ng VCM, Martín-Pintado N, Heddi B, Phan AT. Structure of the human telomere in Na+ solution: an antiparallel (2+2) G-quadruplex scaffold reveals additional diversity. Nucleic Acids Res 2013; 41:10556-62. [PMID: 23999095 PMCID: PMC3905899 DOI: 10.1093/nar/gkt771] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Single-stranded DNA overhangs at the ends of human telomeric repeats are capable of adopting four-stranded G-quadruplex structures, which could serve as potential anticancer targets. Out of the five reported intramolecular human telomeric G-quadruplex structures, four were formed in the presence of K+ ions and only one in the presence of Na+ ions, leading often to a perception that this structural polymorphism occurs exclusively in the presence of K+ but not Na+. Here we present the structure of a new antiparallel (2+2) G-quadruplex formed by a derivative of a 27-nt human telomeric sequence in Na+ solution, which comprises a novel core arrangement distinct from the known topologies. This structure complements the previously elucidated basket-type human telomeric G-quadruplex to serve as reference structures in Na+-containing environment. These structures, together with the coexistence of other conformations in Na+ solution as observed by nuclear magnetic resonance spectroscopy, establish the polymorphic nature of human telomeric repeats beyond the influence of K+ ions.
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Affiliation(s)
- Kah Wai Lim
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, School of Biological Sciences, Nanyang Technological University, 637551 Singapore and Instituto de Química Física Rocasolano, CSIC, 28006 Madrid, Spain
| | - Veronica Chinn Min Ng
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, School of Biological Sciences, Nanyang Technological University, 637551 Singapore and Instituto de Química Física Rocasolano, CSIC, 28006 Madrid, Spain
| | - Nerea Martín-Pintado
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, School of Biological Sciences, Nanyang Technological University, 637551 Singapore and Instituto de Química Física Rocasolano, CSIC, 28006 Madrid, Spain
| | - Brahim Heddi
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, School of Biological Sciences, Nanyang Technological University, 637551 Singapore and Instituto de Química Física Rocasolano, CSIC, 28006 Madrid, Spain
| | - Anh Tuân Phan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, School of Biological Sciences, Nanyang Technological University, 637551 Singapore and Instituto de Química Física Rocasolano, CSIC, 28006 Madrid, Spain
- *To whom correspondence should be addressed. Tel: +65 6514 1915; Fax: +65 6795 7981;
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298
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Zachová D, Fojtová M, Dvořáčková M, Mozgová I, Lermontova I, Peška V, Schubert I, Fajkus J, Sýkorová E. Structure-function relationships during transgenic telomerase expression in Arabidopsis. PHYSIOLOGIA PLANTARUM 2013; 149:114-26. [PMID: 23278240 DOI: 10.1111/ppl.12021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 05/11/2023]
Abstract
Although telomerase (EC 2.7.7.49) is important for genome stability and totipotency of plant cells, the principles of its regulation are not well understood. Therefore, we studied subcellular localization and function of the full-length and truncated variants of the catalytic subunit of Arabidopsis thaliana telomerase, AtTERT, in planta. Our results show that multiple sites in AtTERT may serve as nuclear localization signals, as all the studied individual domains of the AtTERT were targeted to the nucleus and/or the nucleolus. Although the introduced genomic or cDNA AtTERT transgenes display expression at transcript and protein levels, they are not able to fully complement the lack of telomerase functions in tert -/- mutants. The failure to reconstitute telomerase function in planta suggests a more complex telomerase regulation in plant cells than would be expected based on results of similar experiments in mammalian model systems.
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Affiliation(s)
- Dagmar Zachová
- Faculty of Science and Central European Institute of Technology, Masaryk University, CZ-61137, Brno, Czech Republic
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299
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Roger L, Jones RE, Heppel NH, Williams GT, Sampson JR, Baird DM. Extensive telomere erosion in the initiation of colorectal adenomas and its association with chromosomal instability. J Natl Cancer Inst 2013; 105:1202-11. [PMID: 23918447 DOI: 10.1093/jnci/djt191] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Telomere shortening, dysfunction, and fusion may facilitate the acquisition of large-scale genomic rearrangements, driving clonal evolution and tumor progression. The relative contribution that telomere dysfunction and/or APC mutation play in the chromosome instability that occurs during colorectal tumorigenesis is not clear. METHODS We used high-resolution telomere length and fusion analysis to analyze 85 adenomatous colorectal polyps obtained from 10 patients with familial adenomatous polyposis and a panel of 50 colorectal carcinomas with patient-matched normal colonic mucosa. Telomerase activity was determined using the telomeric repeat amplification protocol. Array-CGH was used to detect large-scale genomic rearrangements. Pearson correlation and Student t test were used, and all statistical tests were two-sided. RESULTS Despite the presence of telomerase activity, we observed apparent telomere shortening in colorectal polyps that correlated with large-scale genomic rearrangements (P < .0001) but was independent of polyp size and indistinguishable from that observed in colorectal carcinomas (P = .82). We also observed apparent lengthening of telomeres in both polyps and carcinomas. The extensive differences in mean telomere length of up to 4.6kb between patient-matched normal mucosa and polyps were too large to be accounted for by replicative telomere erosion alone. Telomere fusion events were detected in both polyps and carcinomas; the mutational spectrum accompanying fusion was consistent with alternative nonhomologous end joining. CONCLUSIONS Telomere length distributions observed in colorectal polyps reflect the telomere length composition of the normal originating cells from which clonal growth was initiated. Originating cells containing both short telomeres and APC mutations may give rise to polyps that exhibit short telomeres and are prone to telomere dysfunction, driving genomic instability and progression to malignancy. J Natl Cancer Inst;2013;105:1202-1211.
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Affiliation(s)
- Laureline Roger
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, UK
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300
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Ozturk S, Sozen B, Demir N. Telomere length and telomerase activity during oocyte maturation and early embryo development in mammalian species. Mol Hum Reprod 2013; 20:15-30. [DOI: 10.1093/molehr/gat055] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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