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The Telomerase Inhibitor MST-312 Interferes with Multiple Steps in the Herpes Simplex Virus Life Cycle. J Virol 2015; 89:9804-16. [PMID: 26178994 DOI: 10.1128/jvi.01006-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 07/10/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The life cycle of herpes simplex virus (HSV) has the potential to be further manipulated to yield novel, more effective therapeutic treatments. Recent research has demonstrated that HSV-1 can increase telomerase activity and that expression of the catalytic component of telomerase, telomerase reverse transcriptase (TERT), alters sensitivity to HSV-dependent apoptosis. Telomerase is a cellular enzyme that synthesizes nucleotide repeats at the ends of chromosomes (telomeres), which prevents shortening of the 3' ends of DNA with each cell division. Once telomeres reach a critical length, cells undergo senescence and apoptosis. Here, we used a cell-permeable, reversible inhibitor of the telomerase enzyme, MST-312, to investigate telomerase activity during HSV infection. Human mammary epithelial cells immortalized through TERT expression and human carcinoma HEp-2 cells were infected with the KOS1.1 strain of HSV-1 in the presence of MST-312. MST-312 treatment reduced the number of cells displaying a cytopathic effect and the accumulation of immediate early and late viral proteins. Moreover, the presence of 20 μM to 100 μM MST-312 during infection led to a 2.5- to 5.5-log10 decrease in viral titers. MST-312 also inhibited the replication of HSV-2 and a recent clinical isolate of HSV-1. Additionally, we determined that MST-312 has the largest impact on viral events that take place prior to 5 h postinfection (hpi). Furthermore, MST-312 treatment inhibited virus replication, as measured by adsorption assays and quantification of genome replication. Together, these findings demonstrate that MST-312 interferes with the HSV life cycle. Further investigation into the mechanism for MST-312 is warranted and may provide novel targets for HSV therapies. IMPORTANCE Herpes simplex virus (HSV) infections can lead to cold sores, blindness, and brain damage. Identification of host factors that are important for the virus life cycle may provide novel targets for HSV antivirals. One such factor, telomerase, is the cellular enzyme that synthesizes DNA repeats at the ends of chromosomes during replication to prevent DNA shortening. In this study, we investigate role of telomerase in HSV infection. The data demonstrate that the telomerase inhibitor MST-312 suppressed HSV replication at multiple steps of viral infection.
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Vogan JM, Collins K. Dynamics of Human Telomerase Holoenzyme Assembly and Subunit Exchange across the Cell Cycle. J Biol Chem 2015; 290:21320-35. [PMID: 26170453 DOI: 10.1074/jbc.m115.659359] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Indexed: 01/04/2023] Open
Abstract
Human telomerase acts on telomeres during the genome synthesis phase of the cell cycle, accompanied by its concentration in Cajal bodies and transient colocalization with telomeres. Whether the regulation of human telomerase holoenzyme assembly contributes to the cell cycle restriction of telomerase function is unknown. We investigated the steady-state levels, assembly, and exchange dynamics of human telomerase subunits with quantitative in vivo cross-linking and other methods. We determined the physical association of telomerase subunits in cells blocked or progressing through the cell cycle as synchronized by multiple protocols. The total level of human telomerase RNA (hTR) was invariant across the cell cycle. In vivo snapshots of telomerase holoenzyme composition established that hTR remains bound to human telomerase reverse transcriptase (hTERT) throughout all phases of the cell cycle, and subunit competition assays suggested that hTERT-hTR interaction is not readily exchangeable. In contrast, the telomerase holoenzyme Cajal body-associated protein, TCAB1, was released from hTR in mitotic cells coincident with TCAB1 delocalization from Cajal bodies. This telomerase holoenzyme disassembly was reversible with cell cycle progression without any change in total TCAB1 protein level. Consistent with differential cell cycle regulation of hTERT-hTR and TCAB1-hTR protein-RNA interactions, overexpression of hTERT or TCAB1 had limited if any influence on hTR assembly of the other subunit. Overall, these findings revealed a cell cycle regulation that disables human telomerase association with telomeres while preserving the co-folded hTERT-hTR ribonucleoprotein catalytic core. Studies here, integrated with previous work, led to a unifying model for telomerase subunit assembly and trafficking in human cells.
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Affiliation(s)
- Jacob M Vogan
- From the Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720
| | - Kathleen Collins
- From the Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720
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Kellermann G, Kaiser M, Dingli F, Lahuna O, Naud-Martin D, Mahuteau-Betzer F, Loew D, Ségal-Bendirdjian E, Teulade-Fichou MP, Bombard S. Identification of human telomerase assembly inhibitors enabled by a novel method to produce hTERT. Nucleic Acids Res 2015; 43:e99. [PMID: 25958399 PMCID: PMC4551907 DOI: 10.1093/nar/gkv425] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 04/20/2015] [Indexed: 01/23/2023] Open
Abstract
Telomerase is the enzyme that maintains the length of telomeres. It is minimally constituted of two components: a core reverse transcriptase protein (hTERT) and an RNA (hTR). Despite its significance as an almost universal cancer target, the understanding of the structure of telomerase and the optimization of specific inhibitors have been hampered by the limited amount of enzyme available. Here, we present a breakthrough method to produce unprecedented amounts of recombinant hTERT and to reconstitute human telomerase with purified components. This system provides a decisive tool to identify regulators of the assembly of this ribonucleoprotein complex. It also enables the large-scale screening of small-molecules capable to interfere with telomerase assembly. Indeed, it has allowed us to identify a compound that inhibits telomerase activity when added prior to the assembly of the enzyme, while it has no effect on an already assembled telomerase. Therefore, the novel system presented here may accelerate the understanding of human telomerase assembly and facilitate the discovery of potent and mechanistically unique inhibitors.
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Affiliation(s)
- Guillaume Kellermann
- INSERM UMR-S 1007, Cellular Homeostasis and Cancer, Paris, France Université Paris Descartes, Paris Sorbonne Cité, Paris, France
| | - Markus Kaiser
- Institut Curie, CMIB, CNRS UMR 9187- INSERM U1196, Orsay, France
| | - Florent Dingli
- Institut Curie/laboratoire de spectrométrie de masse protéomique, Paris, France
| | | | | | | | - Damarys Loew
- Institut Curie/laboratoire de spectrométrie de masse protéomique, Paris, France
| | - Evelyne Ségal-Bendirdjian
- INSERM UMR-S 1007, Cellular Homeostasis and Cancer, Paris, France Université Paris Descartes, Paris Sorbonne Cité, Paris, France
| | | | - Sophie Bombard
- INSERM UMR-S 1007, Cellular Homeostasis and Cancer, Paris, France Université Paris Descartes, Paris Sorbonne Cité, Paris, France
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Wang WJ, Li JJ, Rui K, Gai PP, Zhang JR, Zhu JJ. Sensitive Electrochemical Detection of Telomerase Activity Using Spherical Nucleic Acids Gold Nanoparticles Triggered Mimic-Hybridization Chain Reaction Enzyme-Free Dual Signal Amplification. Anal Chem 2015; 87:3019-26. [DOI: 10.1021/ac504652e] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Wen-Jing Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Jing-Jing Li
- Department
of Radiology, Affiliated Hospital of Xuzhou Medical College, Xuzhou 221006, People’s Republic of China
| | - Kai Rui
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Pan-Pan Gai
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Jian-Rong Zhang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
- School
of Chemistry and Life Science, Nanjing University Jinling College, Nanjing 210089, People’s Republic of China
| | - Jun-Jie Zhu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
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Zhu G, Yang K, Zhang CY. A single quantum dot-based biosensor for telomerase assay. Chem Commun (Camb) 2015; 51:6808-11. [DOI: 10.1039/c5cc01600b] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We develop a single quantum dot-based biosensor for the sensitive detection of telomerase in tumor cells and screening of anticancer drugs.
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Affiliation(s)
- Guichi Zhu
- Single-Molecule Detection and Imaging Laboratory
- Shenzhen Institutes of Advanced Technology
- Chinese Academy of Sciences
- Shenzhen 518055
- China
| | - Kun Yang
- Single-Molecule Detection and Imaging Laboratory
- Shenzhen Institutes of Advanced Technology
- Chinese Academy of Sciences
- Shenzhen 518055
- China
| | - Chun-yang Zhang
- Single-Molecule Detection and Imaging Laboratory
- Shenzhen Institutes of Advanced Technology
- Chinese Academy of Sciences
- Shenzhen 518055
- China
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56
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Gazzaniga FS, Blackburn EH. An antiapoptotic role for telomerase RNA in human immune cells independent of telomere integrity or telomerase enzymatic activity. Blood 2014; 124:3675-84. [PMID: 25320237 PMCID: PMC4263978 DOI: 10.1182/blood-2014-06-582254] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 09/26/2014] [Indexed: 01/28/2023] Open
Abstract
Telomerase is a ribonucleoprotein complex that adds telomeric DNA to the ends of linear chromosomes. It contains two core canonical components: the essential RNA component, hTR, which provides the template for DNA synthesis, and the reverse transcriptase protein component, hTERT. Low telomerase activity in circulating peripheral blood mononuclear cells has been associated with a variety of diseases. It is unknown, however, whether telomerase, in addition to its long-term requirement for telomere maintenance, is also necessary for short-term immune cell proliferation and survival. We report that overexpression of enzymatically inactive hTR mutants protected against dexamethasone-induced apoptosis in stimulated CD4 T cells. Furthermore, hTR knockdown reproducibly induced apoptosis in the absence of any detectable telomere shortening or DNA damage response. In contrast, hTERT knockdown did not induce apoptosis. Strikingly, overexpression of hTERT protein caused apoptosis that was rescued by overexpression of enzymatically inactive hTR mutants. Hence, we propose that hTR can function as a noncoding RNA that protects from apoptosis independent of its function in telomerase enzymatic activity and long-term telomere maintenance in normal human immune cells. These results imply that genetic or environmental factors that alter hTR levels can directly affect immune cell function to influence health and disease.
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Affiliation(s)
- Francesca S Gazzaniga
- Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA
| | - Elizabeth H Blackburn
- Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA
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57
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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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58
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Oxidative stress induces persistent telomeric DNA damage responsible for nuclear morphology change in mammalian cells. PLoS One 2014; 9:e110963. [PMID: 25354277 PMCID: PMC4212976 DOI: 10.1371/journal.pone.0110963] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 09/22/2014] [Indexed: 02/07/2023] Open
Abstract
One main function of telomeres is to maintain chromosome and genome stability. The rate of telomere shortening can be accelerated significantly by chemical and physical environmental agents. Reactive oxygen species are a source of oxidative stress and can produce modified bases (mainly 8-oxoG) and single strand breaks anywhere in the genome. The high incidence of guanine residues in telomeric DNA sequences makes the telomere a preferred target for oxidative damage. Our aim in this work is to evaluate whether chromosome instability induced by oxidative stress is related specifically to telomeric damage. We treated human primary fibroblasts (MRC-5) in vitro with hydrogen peroxide (100 and 200 µM) for 1 hr and collected data at several time points. To evaluate the persistence of oxidative stress-induced DNA damage up to 24 hrs after treatment, we analysed telomeric and genomic oxidative damage by qPCR and a modified comet assay, respectively. The results demonstrate that the genomic damage is completely repaired, while the telomeric oxidative damage persists. The analysis of telomere length reveals a significant telomere shortening 48 hrs after treatment, leading us to hypothesise that residual telomere damage could be responsible for the telomere shortening observed. Considering the influence of telomere length modulation on genomic stability, we quantified abnormal nuclear morphologies (Nucleoplasmic Bridges, Nuclear Buds and Micronuclei) and observed an increase of chromosome instability in the same time frame as telomere shortening. At subsequent times (72 and 96 hrs), we observed a restoration of telomere length and a reduction of chromosome instability, leaving us to conjecture a correlation between telomere shortening/dysfunction and chromosome instability. We can conclude that oxidative base damage leads to abnormal nuclear morphologies and that telomere dysfunction is an important contributor to this effect.
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59
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Alberti L, Renaud S, Losi L, Leyvraz S, Benhattar J. High expression of hTERT and stemness genes in BORIS/CTCFL positive cells isolated from embryonic cancer cells. PLoS One 2014; 9:e109921. [PMID: 25279549 PMCID: PMC4184884 DOI: 10.1371/journal.pone.0109921] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 09/12/2014] [Indexed: 01/08/2023] Open
Abstract
BORIS/CTCFL is a member of cancer testis antigen family normally expressed in germ cells. In tumors, it is aberrantly expressed although its functions are not completely well-defined. To better understand the functions of BORIS in cancer, we selected the embryonic cancer cells as a model. Using a molecular beacon, which specifically targets BORIS mRNA, we demonstrated that BORIS positive cells are a small subpopulation of tumor cells (3–5% of total). The BORIS-positive cells isolated using BORIS-molecular beacon, expressed higher telomerase hTERT, stem cell (NANOG, OCT4, SOX2) and cancer stem cell marker genes (CD44 and ALDH1) compared to the BORIS-negative tumor cells. In order to define the functional role of BORIS, stable BORIS-depleted embryonic cancer cells were generated. BORIS silencing strongly down-regulated the expression of hTERT, stem cell and cancer stem cell marker genes. Moreover, the BORIS knockdown increased cellular senescence in embryonic cancer cells, revealing a putative role of BORIS in the senescence biological program. Our data indicate an association of BORIS expressing cells subpopulation with the expression of stemness genes, highlighting the critical role played by BORIS in embryonic neoplastic disease.
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Affiliation(s)
- Loredana Alberti
- Institute of Pathology, Lausanne University Hospital, Lausanne, Switzerland
| | - Stéphanie Renaud
- Institute of Biotechnology, University of Lausanne, Lausanne, Switzerland
| | - Lorena Losi
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Serge Leyvraz
- Department of Oncology, Lausanne University Hospital, Lausanne, Switzerland
| | - Jean Benhattar
- Institute of Pathology, Lausanne University Hospital, Lausanne, Switzerland
- Biopath Lab, Lausanne, Switzerland
- * E-mail:
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60
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Ilyinsky NS, Shchyolkina AK, Borisova OF, Mamaeva OK, Zvereva MI, Azhibek DM, Livshits MA, Mitkevich VA, Balzarini J, Sinkevich YB, Luzikov YN, Dezhenkova LG, Kolotova ES, Shtil AA, Shchekotikhin AE, Kaluzhny DN. Novel multi-targeting anthra[2,3-b]thiophene-5,10-diones with guanidine-containing side chains: interaction with telomeric G-quadruplex, inhibition of telomerase and topoisomerase I and cytotoxic properties. Eur J Med Chem 2014; 85:605-14. [PMID: 25127152 DOI: 10.1016/j.ejmech.2014.08.030] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 08/05/2014] [Accepted: 08/07/2014] [Indexed: 01/07/2023]
Abstract
Novel generations of antitumor anthraquinones are expected to be advantageous over the conventional chemotherapeutic agents. Previous structure-activity relationship studies demonstrated an importance of the positively charged side chains conjugated to anthra[2,3-b]thiophene-5,10-dione scaffolds. Exploring a role of individual side chain moieties in binding to the duplex and G-quadruplex DNA, modulation of telomerase and topoisomerase I activities, intracellular accumulation and cytostatic potency, we herein analyzed a series of reported and newly synthesized guanidine-containing derivatives of anthra[2,3-b]thiophene-5,10-dione. We found that the number of cationic side chains (namely, two) is critical for a tight interaction with human telomeric G-quadruplex (TelQ). Along with a larger drug-TelQ association constant, the telomerase attenuation by anthrathiophenediones with two basic groups in the side chains was more pronounced than by the analogs bearing one basic group. For mono-guanidinated compounds the substituent with the amino group in the side chain provided better TelQ affinity than the methylamine residue. The intracellular uptake of the mono-guanidino derivative with two side chains was >2-fold higher than the respective value for the bis(guanidino) derivative. This difference can explain a lower antiproliferative potency of bis(guanidine) containing compounds. Thus, the modifications of side chains of anthra[2,3-b]thiophene-5,10-dione differently modulated drug-target interactions and cellular effects. Nevertheless, the selected compound 11-(3-aminopropylamino)-4-(2-guanidinoethylamino)anthra[2,3-b]thiophene-5,10-dione 13 demonstrated a high affinity to TelQ and the ability to stabilize the quadruplex structure. These properties were paralleled by reasonable potency of 13 as a telomerase/topoisomerase I inhibitor and an antiproliferative agent. These results indicate that the structural elements of anthra[2,3-b]thiophene-5,10-dione derivatives can be balanced to yield a candidate for further preclinical study.
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Affiliation(s)
- Nikolay S Ilyinsky
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 119991, Russia; Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, 9 Institutskiy Per., Dolgoprudny 141700, Russia.
| | - Anna K Shchyolkina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 119991, Russia
| | - Olga F Borisova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 119991, Russia
| | - Olga K Mamaeva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 119991, Russia
| | - Maria I Zvereva
- Department of Chemistry, Lomonosov Moscow State University, GSP-1, 1-3 Leninskie Gory, Moscow 119991, Russia
| | - Dulat M Azhibek
- Department of Chemistry, Lomonosov Moscow State University, GSP-1, 1-3 Leninskie Gory, Moscow 119991, Russia; Skolkovo Institute of Science and Technology, 100 Novaya Street, Skolkovo 143025, Russia
| | - Mikhail A Livshits
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 119991, Russia; Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, 9 Institutskiy Per., Dolgoprudny 141700, Russia
| | - Vladimir A Mitkevich
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 119991, Russia
| | - Jan Balzarini
- Rega Institute for Medical Research, KU Leuven, 3000 Leuven, Belgium
| | - Yuri B Sinkevich
- Mendeleyev University of Chemical Technology, 9 Miusskaya Square, Moscow 125190, Russia
| | - Yuri N Luzikov
- Gause Institute of New Antibiotics, 11 B. Pirogovskaya Street, Moscow 119021, Russia
| | - Lybov G Dezhenkova
- Gause Institute of New Antibiotics, 11 B. Pirogovskaya Street, Moscow 119021, Russia
| | - Ekaterina S Kolotova
- Blokhin Cancer Center, 24 Kashirskoye Shosse, Moscow 115478, Russia; Moscow Engineering and Physics Institute, 31 Kashirskoye Shosse, Moscow 115409, Russia
| | - Alexander A Shtil
- Blokhin Cancer Center, 24 Kashirskoye Shosse, Moscow 115478, Russia; Moscow Engineering and Physics Institute, 31 Kashirskoye Shosse, Moscow 115409, Russia
| | - Andrey E Shchekotikhin
- Mendeleyev University of Chemical Technology, 9 Miusskaya Square, Moscow 125190, Russia; Gause Institute of New Antibiotics, 11 B. Pirogovskaya Street, Moscow 119021, Russia
| | - Dmitry N Kaluzhny
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 119991, Russia
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Distribution of TTAGG-specific telomerase activity in insects. Chromosome Res 2014; 22:495-503. [DOI: 10.1007/s10577-014-9436-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 06/17/2014] [Accepted: 07/10/2014] [Indexed: 01/06/2023]
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62
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Recombinogenic telomeres in diploid Sorex granarius (Soricidae, Eulipotyphla) fibroblast cells. Mol Cell Biol 2014; 34:2786-99. [PMID: 24842907 DOI: 10.1128/mcb.01697-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The telomere structure in the Iberian shrew Sorex granarius is characterized by unique, striking features, with short arms of acrocentric chromosomes carrying extremely long telomeres (up to 300 kb) with interspersed ribosomal DNA (rDNA) repeat blocks. In this work, we investigated the telomere physiology of S. granarius fibroblast cells and found that telomere repeats are transcribed on both strands and that there is no telomere-dependent senescence mechanism. Although telomerase activity is detectable throughout cell culture and appears to act on both short and long telomeres, we also discovered that signatures of a recombinogenic activity are omnipresent, including telomere-sister chromatid exchanges, formation of alternative lengthening of telomeres (ALT)-associated PML-like bodies, production of telomere circles, and a high frequency of telomeres carrying marks of a DNA damage response. Our results suggest that recombination participates in the maintenance of the very long telomeres in normal S. granarius fibroblasts. We discuss the possible interplay between the interspersed telomere and rDNA repeats in the stabilization of the very long telomeres in this organism.
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63
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Dong W, Qian Y, Yang L. Telomerase, hTERT and splice variants in patients with myelodysplastic syndromes. Leuk Res 2014; 38:830-5. [PMID: 24844605 DOI: 10.1016/j.leukres.2014.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 04/07/2014] [Accepted: 04/21/2014] [Indexed: 01/17/2023]
Abstract
Telomeres are specialized structures maintaining chromosome integrity during cellular division and preventing from premature senescence and apoptosis. The rate-limiting component of telomerase is human telomerase reverse transcriptase (hTERT), for which multiple transcripts exist. The aim of this work was to characterize hTERT splice variants in MDS and its relation to telomerase activity, telomere length and hTERT expression. The telomere length in PBMCs of patients with MDS cases was significantly shorter compared to controls (n=30, p=0.002). MDS patients had significantly higher basal telomerase activity (p=0.022) and higher total hTERT (p=0.007), α+β+ hTERT variant (p=0.016) and α+β- hTERT variant expression than control. The ratio of α+β- transcript to α+β+ transcript was significantly increased in cases (p=0.039). This study provided a detailed insight into the hTERT transcript pattern in MDS while correlation analysis showed that only telomerase activity was significantly correlated with total hTERT expression in MDS.
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Affiliation(s)
- Wen Dong
- Department of Orthopaedic Surgery, Tianjin Hongqiao Hospital, Tianjin, PR China
| | - Yaqin Qian
- Department of Immunology, Tianjin Cancer Institute and Hospital, Tianjin Medical University, PR China; National Clinical Research Center of Cancer, PR China; Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, PR China
| | - Lili Yang
- Department of Immunology, Tianjin Cancer Institute and Hospital, Tianjin Medical University, PR China; National Clinical Research Center of Cancer, PR China; Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, PR China.
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Jung HM, Phillips BL, Chan EK. miR-375 activates p21 and suppresses telomerase activity by coordinately regulating HPV E6/E7, E6AP, CIP2A, and 14-3-3ζ. Mol Cancer 2014; 13:80. [PMID: 24708873 PMCID: PMC4021670 DOI: 10.1186/1476-4598-13-80] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 03/31/2014] [Indexed: 12/19/2022] Open
Abstract
Background While microRNAs (miRNAs) are extensively studied in post-transcriptional regulation of gene expressions in many biological processes, cellular miRNA-mediated regulation of viral genes remains unclear. In particular, the interplay between human papillomavirus (HPV) genes and miRNAs and how these interactions contribute to HPV-associated cancers remain elusive. Methods Transient transfection of miR-375-mimic was used to compensate the loss-of-function of miR-375 in HPV-positive cancer. Regulation of oncogenic molecules and their downstream molecules via miR-375 in HPV-positive cancer was investigated using qRT-PCR, western blot, dual luciferase assay, indirect immunofluorescence analysis. All experiments were conducted at least three times to achieve statistical significance determined by Student t-test. Results In this study, we demonstrated how miR-375 negatively regulates HPV16 and 18 transcripts. We also found a cellular protein, E6-associated protein (E6AP), directly regulated by miR-375. miR-375-mediated repression of HPV transcripts and E6AP elevated major tumor suppressors p53, p21, and retinoblastoma protein 1 (RB). Cooperative regulation of miR-375 targets along with the increase of tumor suppressors led to ~60% reduction of telomerase reverse transcriptase (TERT) transcription followed by ~35% decrease of telomerase activity. Furthermore, miR-375-mediated regulation of 14-3-3ζ contributes to decrease telomerase activity by altering nuclear translocation of TERT. Conclusion Taken together, miR-375-mediated suppression of multiple oncogenic components in HPV-associated carcinogenesis generates a cumulative biological response to rescue key tumor suppressors and diminish telomerase activity, which results in cell cycle arrest and cell proliferation inhibition.
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Affiliation(s)
| | | | - Edward Kl Chan
- Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL 32610, USA.
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Olivieri F, Lazzarini R, Recchioni R, Marcheselli F, Rippo MR, Di Nuzzo S, Albertini MC, Graciotti L, Babini L, Mariotti S, Spada G, Abbatecola AM, Antonicelli R, Franceschi C, Procopio AD. MiR-146a as marker of senescence-associated pro-inflammatory status in cells involved in vascular remodelling. AGE (DORDRECHT, NETHERLANDS) 2013; 35:1157-72. [PMID: 22692818 PMCID: PMC3705128 DOI: 10.1007/s11357-012-9440-8] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 05/16/2012] [Indexed: 06/01/2023]
Abstract
In order to identify new markers of vascular cell senescence with potential in vivo implications, primary cultured endothelial cells, including human umbilical vein endothelial cells (HUVECs), human aortic endothelial cells (HAECs), human coronary artery endothelial cells (HCAECs) and ex vivo circulating angiogenic cells (CACs), were analysed for microRNA (miR) expression. Among the 367 profiled miRs in HUVECs, miR-146a, miR-9, miR-204 and miR-367 showed the highest up-regulation in senescent cells. Their predicted target genes belong to nine common pathways, including Toll-like receptor signalling (TLR) that plays a pivotal role in inflammatory response, a key feature of senescence (inflammaging). MiR-146a was the most up-regulated miR in the validation analysis (>10-fold). Mimic and antagomir transfection confirmed TLR's IL-1 receptor-associated kinase (IRAK1) protein modulation in both young and senescent cells. Significant correlations were observed among miR-146a expression and β-galactosidase expression, telomere length and telomerase activity. MiR-146a hyper-expression was also validated in senescent HAECs (>4-fold) and HCAECs (>30-fold). We recently showed that CACs from patients with chronic heart failure (CHF) presented a distinguishing feature of senescence. Therefore, we also included miR-146a expression determination in CACs from 37 CHF patients and 35 healthy control subjects (CTR) for this study. Interestingly, a 1,000-fold increased expression of miR-146a was observed in CACs of CHF patients compared to CTR, along with decreased expression of IRAK1 protein. Moreover, significant correlations among miR-146a expression, telomere length and telomerase activity were observed. Overall, our findings indicate that miR-146a is a marker of a senescence-associated pro-inflammatory status in vascular remodelling cells.
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Affiliation(s)
- Fabiola Olivieri
- />Department of Clinical and Molecular Sciences, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Ancona, Italy
- />Center of Clinical Pathology and Innovative Therapy, IRCCS-INRCA, National Institute, Ancona, Italy
| | - Raffaella Lazzarini
- />Department of Clinical and Molecular Sciences, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Ancona, Italy
- />Center of Clinical Pathology and Innovative Therapy, IRCCS-INRCA, National Institute, Ancona, Italy
| | - Rina Recchioni
- />Center of Clinical Pathology and Innovative Therapy, IRCCS-INRCA, National Institute, Ancona, Italy
| | - Fiorella Marcheselli
- />Center of Clinical Pathology and Innovative Therapy, IRCCS-INRCA, National Institute, Ancona, Italy
| | - Maria Rita Rippo
- />Department of Clinical and Molecular Sciences, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Ancona, Italy
| | - Silvia Di Nuzzo
- />Department of Clinical and Molecular Sciences, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Ancona, Italy
| | - Maria Cristina Albertini
- />Dipartimento di Scienze Biomolecolari, Sezione di Biochimica e Biologia molecolare, Università degli Studi di Urbino “Carlo Bo”, Urbino, Italy
| | - Laura Graciotti
- />Department of Clinical and Molecular Sciences, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Ancona, Italy
| | - Lucia Babini
- />Department of Clinical and Molecular Sciences, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Ancona, Italy
| | - Serena Mariotti
- />Center of Clinical Pathology and Innovative Therapy, IRCCS-INRCA, National Institute, Ancona, Italy
| | - Giorgio Spada
- />Dipartimento di Scienze di Base e Fondamenti, Università degli Studi di Urbino “Carlo Bo”, Urbino, Italy
| | | | | | - Claudio Franceschi
- />Department of Experimental Pathology, “Alma Mater Studiorum” University of Bologna, Bologna, Italy
- />Centro Interdipartimentale Galvani “CIG”, Alma Mater Studiorum University of Bologna, Bologna, Italy
| | - Antonio Domenico Procopio
- />Department of Clinical and Molecular Sciences, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Ancona, Italy
- />Center of Clinical Pathology and Innovative Therapy, IRCCS-INRCA, National Institute, Ancona, Italy
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Neumann F, Kaddu-Mulindwa D, Widmann T, Preuss KD, Held G, Zwick C, Roemer K, Pfreundschuh M, Kubuschok B. EBV-transformed lymphoblastoid cell lines as vaccines against cancer testis antigen-positive tumors. Cancer Immunol Immunother 2013; 62:1211-22. [PMID: 23619976 PMCID: PMC11028802 DOI: 10.1007/s00262-013-1412-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 02/28/2013] [Indexed: 12/25/2022]
Abstract
EBV-transformed lymphoblastoid cell lines (LCL) are potent antigen-presenting cells. To investigate their potential use as cancer testis antigen (CTA) vaccines, we studied the expression of 12 cancer testis (CT) genes in 20 LCL by RT-PCR. The most frequently expressed CT genes were SSX4 (50 %), followed by GAGE (45 %), SSX1 (40 %), MAGE-A3 and SSX2 (25 %), SCP1, HOM-TES-85, MAGE-C1, and MAGE-C2 (15 %). NY-ESO-1 and MAGE-A4 were found in 1/20 LCL and BORIS was not detected at all. Fifteen of 20 LCL expressed at least one antigen, 9 LCL expressed ≥2 CT genes, and 7 of the 20 LCL expressed ≥4 CT genes. The expression of CT genes did not correlate with the length of in vitro culture, telomerase activity, aneuploidy, or proliferation state. While spontaneous expression of CT genes determined by real-time PCR and Western blot was rather weak in most LCL, treatment with DNA methyltransferase 1 inhibitor alone or in combination with histone deacetylase inhibitors increased CTA expression considerably thus enabling LCL to induce CTA-specific T cell responses. The stability of the CT gene expression over prolonged culture periods makes LCL attractive candidates for CT vaccines both in hematological neoplasias and solid tumors.
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Affiliation(s)
- Frank Neumann
- Department of Internal Medicine I, José Carreras-Center for Immuno- and Gene Therapy, University of Saarland Medical School, 66421, Homburg, Saar, Germany,
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67
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Dang-Nguyen TQ, Haraguchi S, Akagi S, Somfai T, Kaneda M, Watanabe S, Kikuchi K, Tajima A, Nagai T. Telomere elongation during morula-to-blastocyst transition in cloned porcine embryos. Cell Reprogram 2013. [PMID: 23194454 DOI: 10.1089/cell.2012.0045] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Although telomeres are elongated during morula-to-blastocyst transition in cloned embryos, it is still unknown whether donor cell types have any effect on this elongation. In the present study, we examined the changes of telomere length during morula-to-blastocyst transition in cloned porcine embryos using different types of donor cells. Porcine embryonic stem-like cells (pESLCs), porcine cumulus cells (PCs), and porcine embryonic fibroblasts at passages 7 and 10 (PEF7s and PEF10s, respectively) were used as donor cells. Telomere lengths of pESLCs (35.8±1.5 kb), PCs (24.4±0.5 kb), PEF7s (18.7±0.6 kb), and PEF10s (17.2±0.1 kb) were significantly different. In contrast, telomere length in morulae derived from pESLCs (18.2±0.3 kb), PC (17.8±0.7 kb), PEF7 (18.5±0.3 kb), and PEF10 (18.4±0.4 kb) did not differ significantly. Likewise, telomeres in blastocysts derived from pESLCs (22.3±1.5 kb), PCs (23.5±2.6 kb), PEF7s (20.2±1.0 kb), and PEF10s (20.9±1.0 kb) had similar lengths. However, telomeres in blastocysts were significant longer (p<0.05) compared with morulae in each group. Relative telomerase activities of morulae derived from pESLCs (4.2±0.4), PCs (4.0±0.5), PEF7s (5.1±0.4), and PEF10s (4.9±0.4) were significantly lower (p<0.01) than those of blastocysts derived from pESLCs (8.2±1.1), PCs (8.6±0.6), PEF7s (12.5±2.9), and PEF10s (8.3±1.1). In conclusion, the telomere elongation in cloned pig embryos that occurred during morula-to-blastocyst transition may be related to the rise of telomerase activity. The telomere elongation may also be independent of the type and telomere length of the donor cell.
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Affiliation(s)
- Thanh Quang Dang-Nguyen
- Department of Animal Breeding and Reproduction, NARO Institute of Livestock and Grassland Science, Ibaraki 305-0901, Japan.
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68
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Listerman I, Sun J, Gazzaniga FS, Lukas JL, Blackburn EH. The major reverse transcriptase-incompetent splice variant of the human telomerase protein inhibits telomerase activity but protects from apoptosis. Cancer Res 2013; 73:2817-28. [PMID: 23610451 DOI: 10.1158/0008-5472.can-12-3082] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Human telomerase reverse transcriptase (hTERT; the catalytic protein subunit of telomerase) is subjected to numerous alternative splicing events, but the regulation and function of these splice variants is obscure. Full-length hTERT includes conserved domains that encode reverse transcriptase activity, RNA binding, and other functions. The major splice variant termed α+β- or β-deletion is highly expressed in stem and cancer cells, where it codes for a truncated protein lacking most of the reverse transcriptase domain but retaining the known RNA-binding motifs. In a breast cancer cell panel, we found that β-deletion was the hTERT transcript that was most highly expressed. Splicing of this transcript was controlled by the splice regulators SRSF11, HNRNPH2, and HNRNPL, and the β-deletion transcript variant was associated with polyribosomes in cells. When ectopically overexpressed, β-deletion protein competed for binding to telomerase RNA (hTR/TERC), thereby inhibiting endogenous telomerase activity. Overexpressed β-deletion protein localized to the nucleus and mitochondria and protected breast cancer cells from cisplatin-induced apoptosis. Our results reveal that a major hTERT splice variant can confer a growth advantage to cancer cells independent of telomere maintenance, suggesting that hTERT makes multiple contributions to cancer pathophysiology.
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Affiliation(s)
- Imke Listerman
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California, USA
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69
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Highly sensitive detection of telomerase activity in tumor cells by cascade isothermal signal amplification based on three-way junction and base-stacking hybridization. Biosens Bioelectron 2013; 41:764-70. [DOI: 10.1016/j.bios.2012.10.009] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 09/21/2012] [Accepted: 10/02/2012] [Indexed: 12/23/2022]
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70
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Leeansyah E, Cameron PU, Solomon A, Tennakoon S, Velayudham P, Gouillou M, Spelman T, Hearps A, Fairley C, Smit DV, Pierce AB, Armishaw J, Crowe SM, Cooper DA, Koelsch KK, Liu JP, Chuah J, Lewin SR. Inhibition of telomerase activity by human immunodeficiency virus (HIV) nucleos(t)ide reverse transcriptase inhibitors: a potential factor contributing to HIV-associated accelerated aging. J Infect Dis 2013; 207:1157-65. [PMID: 23303810 DOI: 10.1093/infdis/jit006] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Human immunodeficiency virus (HIV)-infected patients on combination active antiretroviral therapy (cART) are at increased risk of age-related complications. We hypothesized that nucleos(t)ide reverse transcriptase inhibitors (NRTI) may contribute to accelerated aging in HIV-infected individuals on cART via inhibition of telomerase activity. METHODS Telomerase activity and telomere length (TL) were measured by quantitative polymerase chain reaction in vitro in activated peripheral blood mononuclear cells (PBMCs) cultured with NRTI and ex vivo in PBMCs from uninfected patients exposed to NRTI and from HIV-infected patients on NRTI-containing cART. RESULTS Lamivudine, abacavir, zidovudine, emtricitabine, and tenofovir significantly inhibited telomerase activity in activated PBMCs in vitro. Tenofovir was the most potent inhibitor of telomerase activity and caused greatest shortening of TL in vitro at the therapeutic concentration of 0.3 μM. PBMCs from HIV-infected patients receiving NRTI-containing cART (n = 39) had significantly lower telomerase activity than HIV-uninfected patients (n = 47; P = .011) and HIV-infected patients receiving non-NRTI-containing cART (n = 11; P < .001). TL was significantly inversely associated with age (P = .009) and the total duration on any NRTI (P = .01). CONCLUSIONS NRTIs and, specifically tenofovir at therapeutic concentrations, inhibit telomerase activity leading to accelerated shortening of TL in activated PBMCs. The relationship between NRTI, reduced telomerase activity, and accelerated aging requires further investigation in HIV-infected individuals on cART.
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Affiliation(s)
- Edwin Leeansyah
- Department of Medicine, Monash University, Melbourne, Australia
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71
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Tian L, Weizmann Y. Real-Time Detection of Telomerase Activity Using the Exponential Isothermal Amplification of Telomere Repeat Assay. J Am Chem Soc 2012. [DOI: 10.1021/ja309198j] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Leilei Tian
- Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois
60637, United States
| | - Yossi Weizmann
- Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois
60637, United States
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72
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Berardinelli F, Nieri D, Sgura A, Tanzarella C, Antoccia A. Telomere loss, not average telomere length, confers radiosensitivity to TK6-irradiated cells. Mutat Res 2012; 740:13-20. [PMID: 23220250 DOI: 10.1016/j.mrfmmm.2012.11.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 11/20/2012] [Accepted: 11/22/2012] [Indexed: 06/01/2023]
Abstract
Many and varied are the proposed mechanisms that lead to resistance to ionizing radiation treatment. Among them, an inverse relationship between telomere length and radioresistance has been recently advanced. Investigating such a relationship in TK6 lymphoblasts, we found that clones originating from cells survived to 4Gy of X-rays showed a significantly higher telomere length when compared with clones grown from untreated cells. The lengthening observed was not attributable to a radiation-induced increase in telomerase activity, as demonstrated by TRAP assay performed in the dose range of 1-10Gy. Given the evidence that TK6 whole population was characterized by heterogeneity in cellular mean telomere length and telomere loss, we tested the hypothesis that a process of selection may favour cells with longer telomeres (more radioresistant cells) following exposure to irradiation. In order to do this 15 independent TK6 clones were selected and characterized for telomere length and loss on the basis of q-FISH and flow-FISH analysis. Among the screened clones four characterized by long telomeres and four characterized by short telomeres were tested for their radiosensitivity by means of clonogenic assay. The results obtained showed that, in our experimental conditions (cellular model, radiation doses) no significant correlation was observed between radiosensitivity and mean telomere lengths, whereas a positive correlation was observed with respect to telomere loss. Overall, these results indicate that telomere loss and not mean telomere length plays a critical role in the phenomenon of radiosensitivity/radioresistance.
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73
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Dang-Nguyen TQ, Haraguchi S, Furusawa T, Somfai T, Kaneda M, Watanabe S, Akagi S, Kikuchi K, Tajima A, Nagai T. Downregulation of histone methyltransferase genes SUV39H1 and SUV39H2 increases telomere length in embryonic stem-like cells and embryonic fibroblasts in pigs. J Reprod Dev 2012; 59:27-32. [PMID: 23018532 PMCID: PMC3943233 DOI: 10.1262/jrd.2012-118] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Telomere is a nucleoprotein structure at the ends of chromosomes that helps to protect
the ends of chromosomes from being fused with other chromosomes. Knockout of histone
methyltransferases Suv39h1 and Suv39h2 increases the telomere length in murine cells,
whereas downregulation of SUV39H1 and SUV39H2 genes
decreases the telomere length in human cells, suggesting that telomere biology is
different among mammalian species. However, epigenetic regulation of the telomere has not
been studied in mammals other than the human and mouse. In the present study, the effect
of knockdown of SUV39H1 and SUV39H2 genes on telomere
length was examined in porcine embryonic stem-like cells (pESLCs) and porcine embryonic
fibroblasts (PEFs). The telomeres in SUV39H1 and SUV39H2
knockdown (SUV39KD) pESLCs (37.1 ± 0.9 kb) were longer (P<0.05) compared with those of
the control (33.0 ± 0.7 kb). Similarly, SUV39KD PEFs had longer telomeres (22.1 ± 0.4 kb;
P<0.05) compared with the control (17.8 ± 1.1 kb). Telomerase activities were not
different between SUV39KD pESLCs (10.4 ± 1.7) and the control (10.1 ± 1.7) or between
SUV39KD PEFs (1.0 ± 0.3) and the control (1.0 ± 0.4), suggesting that telomerase
activities did not contribute to the telomere elongation in SUV39KD pESLCs and SUV39KD
PEFs. Relative levels of trimethylation of histone H3 lysine 9 and expressions of
DNMT1, DNMT3A and DNMT3B were
decreased in SUV39KD cells, suggesting that telomere lengthening in SUV39KD pESLCs and
SUV39KD PEFs might be not only related to the loss of histone modification marks but also
linked to the decrease in DNA methyltransferase in pigs.
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Affiliation(s)
- Thanh Quang Dang-Nguyen
- Department of Animal Breeding and Reproduction, NARO Institute of Livestock and Grassland Science, Ibaraki 305-0901, Japan.
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Valproic acid confers functional pluripotency to human amniotic fluid stem cells in a transgene-free approach. Mol Ther 2012; 20:1953-67. [PMID: 22760542 PMCID: PMC3464631 DOI: 10.1038/mt.2012.117] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Induced pluripotent stem cells (iPSCs) with potential for therapeutic applications can be derived from somatic cells via ectopic expression of a set of limited and defined transcription factors. However, due to risks of random integration of the reprogramming transgenes into the host genome, the low efficiency of the process, and the potential risk of virally induced tumorigenicity, alternative methods have been developed to generate pluripotent cells using nonintegrating systems, albeit with limited success. Here, we show that c-KIT+ human first-trimester amniotic fluid stem cells (AFSCs) can be fully reprogrammed to pluripotency without ectopic factors, by culture on Matrigel in human embryonic stem cell (hESC) medium supplemented with the histone deacetylase inhibitor (HDACi) valproic acid (VPA). The cells share 82% transcriptome identity with hESCs and are capable of forming embryoid bodies (EBs) in vitro and teratomas in vivo. After long-term expansion, they maintain genetic stability, protein level expression of key pluripotency factors, high cell-division kinetics, telomerase activity, repression of X-inactivation, and capacity to differentiate into lineages of the three germ layers, such as definitive endoderm, hepatocytes, bone, fat, cartilage, neurons, and oligodendrocytes. We conclude that AFSC can be utilized for cell banking of patient-specific pluripotent cells for potential applications in allogeneic cellular replacement therapies, pharmaceutical screening, and disease modeling.
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Abstract
Human telomerase is a ribonucleoprotein complex that functions as a telomere terminal transferase by adding multiple TTAGGG hexamer repeats using its integral RNA as the template. There is a very strong association between telomerase activity and malignancy in nearly all types of cancer, suggesting that telomerase could be used not only as a diagnostic and prognostic marker but also as a therapeutic target for managing cancer. The significant progress in biomedical telomerase research has necessitated the development of new bioanalytical methods for the rapid, sensitive, and reliable detection of telomerase activity in a particular cell or clinical tissue and body fluids. In this review, we highlight some of the latest methods for identifying telomerase activity and inhibition and discuss some of the challenges for designing innovative telomerase assays. We also summarise the current technologies and speculate on future directions for telomerase testing.
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Affiliation(s)
- Xiaoming Zhou
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China
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76
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Larsen SA, Kassem M, Rattan SI. Glucose metabolite glyoxal induces senescence in telomerase-immortalized human mesenchymal stem cells. Chem Cent J 2012; 6:18. [PMID: 22424056 PMCID: PMC3325881 DOI: 10.1186/1752-153x-6-18] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 03/17/2012] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Various by-products of the cellular metabolism, such as reactive carbonyl species (RCS) are potentially harmful to cells and tissues, and play a role in many physiological and pathological processes. Among various RCS is the highly reactive dicarbonyl glyoxal (GO), which is a natural physiological metabolite produced by the auto-oxidation of glucose, and can form covalent adducts known as advanced glycation endproducts (AGE). We have previously reported that GO accelerates ageing and causes premature senescence in normal human skin fibroblasts. RESULTS Using a bone marrow-derived telomerase-immortalised mesenchymal stem cell line hMSC-TERT we have observed that an exposure of cells to 0.75 mM and 1 mM GO induces irreversible cellular senescence within 3 days. Induction of senescence in hMSC-TERT was demonstrated by a variety of markers, including characteristic cell morphology and enlargement, vacuolisation, multinucleation, induction of senescence associated β-galactosidase, cell cycle arrest, and increased levels of a cell cycle inhibitor p16. These changes were accompanied by increased extent of DNA breaks as measured by the comet assay, and increased levels of the AGE product, carboxymethyl-lysine (CML). Furthermore, the in vitro differentiation potential of hMSC-TERT to become functional osteoblasts was highly reduced in GO-treated stem cells, as determined by alkaline phosphatase (ALP) activity and mineralized matrix (MM) formation. CONCLUSIONS The results of our study imply that an imbalanced glucose metabolism can reduce the functioning ability of stem cells in vivo both during ageing and during stem cell-based therapeutic interventions.
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Affiliation(s)
- Simon Asbjørn Larsen
- Laboratory of Cellular Ageing, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
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Senthilkumar PK, Robertson LW, Ludewig G. PCB153 reduces telomerase activity and telomere length in immortalized human skin keratinocytes (HaCaT) but not in human foreskin keratinocytes (NFK). Toxicol Appl Pharmacol 2011; 259:115-23. [PMID: 22210444 DOI: 10.1016/j.taap.2011.12.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 12/09/2011] [Accepted: 12/14/2011] [Indexed: 02/07/2023]
Abstract
Polychlorinated biphenyls (PCBs), ubiquitous environmental pollutants, are characterized by long term-persistence in the environment, bioaccumulation, and biomagnification in the food chain. Exposure to PCBs may cause various diseases, affecting many cellular processes. Deregulation of the telomerase and the telomere complex leads to several biological disorders. We investigated the hypothesis that PCB153 modulates telomerase activity, telomeres and reactive oxygen species resulting in the deregulation of cell growth. Exponentially growing immortal human skin keratinocytes (HaCaT) and normal human foreskin keratinocytes (NFK) were incubated with PCB153 for 48 and 24days, respectively, and telomerase activity, telomere length, superoxide level, cell growth, and cell cycle distribution were determined. In HaCaT cells exposure to PCB153 significantly reduced telomerase activity, telomere length, cell growth and increased intracellular superoxide levels from day 6 to day 48, suggesting that superoxide may be one of the factors regulating telomerase activity, telomere length and cell growth compared to untreated control cells. Results with NFK cells showed no shortening of telomere length but reduced cell growth and increased superoxide levels in PCB153-treated cells compared to untreated controls. As expected, basal levels of telomerase activity were almost undetectable, which made a quantitative comparison of treated and control groups impossible. The significant down regulation of telomerase activity and reduction of telomere length by PCB153 in HaCaT cells suggest that any cell type with significant telomerase activity, like stem cells, may be at risk of premature telomere shortening with potential adverse health effects for the affected organism.
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Affiliation(s)
- P K Senthilkumar
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA 52242-5000, USA
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78
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Trujillo KA, Hines WC, Vargas KM, Jones AC, Joste NE, Bisoffi M, Griffith JK. Breast field cancerization: isolation and comparison of telomerase-expressing cells in tumor and tumor adjacent, histologically normal breast tissue. Mol Cancer Res 2011; 9:1209-21. [PMID: 21775421 DOI: 10.1158/1541-7786.mcr-10-0424] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Telomerase stabilizes chromosomes by maintaining telomere length, immortalizes mammalian cells, and is expressed in more than 90% of human tumors. However, the expression of human telomerase reverse transcriptase (hTERT) is not restricted to tumor cells. We have previously shown that a subpopulation of human mammary epithelial cells (HMEC) in tumor-adjacent, histologically normal (TAHN) breast tissues expresses hTERT mRNA at levels comparable with levels in breast tumors. In the current study, we first validated a reporter for measuring levels of hTERT promoter activity in early-passage HMECs and then used this reporter to compare hTERT promoter activity in HMECs derived from tumor and paired TAHN tissues 1, 3, and 5 cm from the tumor (TAHN-1, TAHN-3, and TAHN-5, respectively). Cell sorting, quantitative real-time PCR, and microarray analyses showed that the 10% of HMECs with the highest hTERT promoter activity in both tumor and TAHN-1 tissues contain more than 95% of hTERT mRNA and overexpress many genes involved in cell cycle and mitosis. The percentage of HMECs within this subpopulation showing high hTERT promoter activity was significantly reduced or absent in TAHN-3 and TAHN-5 tissues. We conclude that the field of "normal tissue" proximal to the breast tumors contains a population of HMECs similar in hTERT expression levels and in gene expression to the HMECs within the tumor mass and that this population is significantly reduced in tissues more distal to the tumor.
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Affiliation(s)
- Kristina A Trujillo
- Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, MSC08 4670 Albuquerque, New Mexico 87131, USA
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Cannavo I, Benchetrit M, Loubatier C, Michel G, Lemichez E, Giordanengo V. Characterization of a cluster of oncogenic mutations in E6 of a human papillomavirus 83 variant isolated from a high-grade squamous intraepithelial lesion. J Gen Virol 2011; 92:2428-2436. [PMID: 21752964 DOI: 10.1099/vir.0.032888-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We previously isolated human papillomavirus 83 (HPV83m) from a cervical smear. Sequence analysis of E6 and E7 proteins highlighted five mutations located in the second putative zinc-finger region of E6 (E6m), an important domain for protein-protein or protein-DNA interactions. Here, we show that E6m of HPV83m can trigger human primary cell proliferation and anchorage-independent growth properties, similarly to E6 of HPV16, a high-risk HPV (HR-HPV). Interestingly, we demonstrate that, in contrast to E6 of HPV16, E6m corrupts neither p53 stability nor telomerase activity, but acts as a specific modulator of the transcriptional machinery. By studying E6m reversion mutants, we confirmed the importance of the second zinc-finger domain in triggering the observed upregulation of cell growth and of the transcriptional machinery. Reversion of these mutations in E6m (to yield strain E6r) fully abolished the oncogenic potential of E6m, transforming the phenotype of E6 from a high-risk to a low-risk phenotype. Importantly, our data define the importance of a cluster of mutations in the second zinc finger of E6m in increasing the oncogenic potential of HPV83.
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Affiliation(s)
- Isabelle Cannavo
- INSERM, U895, Centre Méditerranéen de Médecine Moléculaire, C3M, Toxines Microbiennes dans la relation hote pathogènes, Nice, France
- Université de Nice-Sophia-Antipolis, UFR Médecine, Nice, France
- Laboratoire de Virologie, Centre Hospitalier Universitaire de Nice, Hôpital Archet 2, Nice, France
| | - Maxime Benchetrit
- Université de Nice-Sophia-Antipolis, UFR Médecine, Nice, France
- Laboratoire d'Anatomo-Pathologie, Centre Hospitalier Universitaire de Nice, Hôpital Archet 2, Nice, France
| | - Céline Loubatier
- INSERM, U895, Centre Méditerranéen de Médecine Moléculaire, C3M, Toxines Microbiennes dans la relation hote pathogènes, Nice, France
- Université de Nice-Sophia-Antipolis, UFR Médecine, Nice, France
| | - Gregory Michel
- INSERM, U895, Centre Méditerranéen de Médecine Moléculaire, C3M, Toxines Microbiennes dans la relation hote pathogènes, Nice, France
| | - Emmanuel Lemichez
- INSERM, U895, Centre Méditerranéen de Médecine Moléculaire, C3M, Toxines Microbiennes dans la relation hote pathogènes, Nice, France
| | - Valérie Giordanengo
- INSERM, U895, Centre Méditerranéen de Médecine Moléculaire, C3M, Toxines Microbiennes dans la relation hote pathogènes, Nice, France
- Université de Nice-Sophia-Antipolis, UFR Médecine, Nice, France
- Laboratoire de Virologie, Centre Hospitalier Universitaire de Nice, Hôpital Archet 2, Nice, France
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80
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Yoon AR, Gao R, Kaul Z, Choi IK, Ryu J, Noble JR, Kato Y, Saito S, Hirano T, Ishii T, Reddel RR, Yun CO, Kaul SC, Wadhwa R. MicroRNA-296 is enriched in cancer cells and downregulates p21WAF1 mRNA expression via interaction with its 3' untranslated region. Nucleic Acids Res 2011; 39:8078-91. [PMID: 21724611 PMCID: PMC3185413 DOI: 10.1093/nar/gkr492] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
MicroRNAs (miRNAs) are a class of noncoding small RNAs that act as negative regulators of gene expression. To identify miRNAs that may regulate human cell immortalization and carcinogenesis, we performed comparative miRNA array profiling of human normal and SV40-T antigen immortalized cells. We found that miR-296 was upregulated in immortalized cells that also had activation of telomerase. By an independent experiment on genomic analysis of cancer cells we found that chromosome region (20q13.32), where miR-296 is located, was amplified in 28/36 cell lines, and most of these showed enriched miR-296 expression. Overexpression of miR-296 in human cancer cells, with and without telomerase activity, had no effect on their telomerase function. Instead, it suppressed p53 function that is frequently downregulated during human cell immortalization and carcinogenesis. By monitoring the activity of a luciferase reporter connected to p53 and p21WAF1 (p21) untranslated regions (UTRs), we demonstrate that miR-296 interacts with the p21-3′UTR, and the Hu binding site of p21-3′UTR was identified as a potential miR-296 target site. We demonstrate for the first time that miR-296 is frequently upregulated during immortalization of human cells and contributes to carcinogenesis by downregulation of p53-p21WAF1 pathway.
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Affiliation(s)
- A-rum Yoon
- National Institute of Advanced Industrial Science & Technology, Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki - 305 8562, Japan
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81
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Senthilkumar PK, Klingelhutz AJ, Jacobus JA, Lehmler H, Robertson LW, Ludewig G. Airborne polychlorinated biphenyls (PCBs) reduce telomerase activity and shorten telomere length in immortal human skin keratinocytes (HaCat). Toxicol Lett 2011; 204:64-70. [PMID: 21530622 DOI: 10.1016/j.toxlet.2011.04.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 04/12/2011] [Accepted: 04/14/2011] [Indexed: 12/17/2022]
Abstract
PCBs, a group of 209 individual congeners, are ubiquitous environmental pollutants and classified as probable human carcinogens. One major route of exposure is by inhalation of these industrial compounds, possibly daily from inner city air and/or indoor air in contaminated buildings. Hallmarks of aging and carcinogenesis are changes in telomere length and telomerase activity. We hypothesize that semi-volatile PCBs, like those found in inner city air, are capable of disrupting telomerase activity and altering telomere length. To explore this possibility, we exposed human skin keratinocytes to a synthetic Chicago Airborne Mixture (CAM) of PCBs, or the prominent airborne PCB congeners, PCB28 or PCB52 for up to 48 days and determined telomerase activity, telomere length, cell proliferation, and cell cycle distribution. PCBs 28, 52 and CAM significantly reduced telomerase activity from days 18-48. Telomere length was shortened by PCB 52 from day 18 and PCB 28 and CAM from days 30 on. All PCBs decreased cell proliferation from day 18; only PCB 52 produced a small increase of cells in G0/G1 of the cell cycle. This significant inhibition of telomerase activity and reduction of telomere length by PCB congeners suggest a potential mechanism by which these compounds could lead to accelerated aging and cancer.
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Affiliation(s)
- P K Senthilkumar
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA, United States
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82
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Peng SW, Guo XY, Shang GG, Li J, Xu XY, You ML, Li P, Chen GQ. An assessment of the risks of carcinogenicity associated with polyhydroxyalkanoates through an analysis of DNA aneuploid and telomerase activity. Biomaterials 2011; 32:2546-55. [DOI: 10.1016/j.biomaterials.2010.12.051] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Accepted: 12/29/2010] [Indexed: 01/23/2023]
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83
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Izadyar F, Wong J, Maki C, Pacchiarotti J, Ramos T, Howerton K, Yuen C, Greilach S, Zhao HH, Chow M, Chow YC, Rao J, Barritt J, Bar-Chama N, Copperman A. Identification and characterization of repopulating spermatogonial stem cells from the adult human testis. Hum Reprod 2011; 26:1296-306. [DOI: 10.1093/humrep/der026] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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84
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Anchelin M, Murcia L, Alcaraz-Pérez F, García-Navarro EM, Cayuela ML. Behaviour of telomere and telomerase during aging and regeneration in zebrafish. PLoS One 2011; 6:e16955. [PMID: 21347393 PMCID: PMC3036734 DOI: 10.1371/journal.pone.0016955] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 01/18/2011] [Indexed: 12/25/2022] Open
Abstract
Telomere length and telomerase activity are important factors in the pathobiology of human diseases. Age-related diseases and premature aging syndromes are characterized by short telomeres, which can compromise cell viability, whereas tumour cells can prevent telomere loss by aberrantly upregulating telomerase. The zebrafish (Danio rerio) offers multiple experimental manipulation advantages over other vertebrate models and, therefore, it has been recently considered as a potential model for aging, cancer, and regeneration studies. However, it has only partially been exploited to shed light on these fundamental biological processes. The aim of this study was, therefore, to investigate telomere length and telomerase expression and activity in different strains of zebrafish obtained from different stock centres to determine whether they undergo any changes during aging and regeneration. We found that although both telomerase expression and telomere length increased from embryo to adulthood stages, they drastically declined in aged fish despite telomerase activity was detected in different tissues of old fish. In addition, we observed a weaker upregulation of telomerase expression in regenerating fins of old fish, which well correlates with their impaired regeneration capacity. Strikingly, telomeres were elongated or maintained during the fin regeneration process at all ages and after repeated amputations, likely to support high cell proliferation rates. We conclude that the expression of telomerase and telomere length are closely related during the entire life cycle of the fish and that these two parameters can be used as biomarkers of aging in zebrafish. Our results also reveal a direct relationship between the expression of telomerase, telomere length and the efficiency of tissue regeneration.
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Affiliation(s)
- Monique Anchelin
- Telomerase, Aging and Cancer Group, Research Unit, Department of Surgery, CIBERehd, University Hospital “Virgen de la Arrixaca”, Murcia, Spain
| | - Laura Murcia
- Telomerase, Aging and Cancer Group, Research Unit, Department of Surgery, CIBERehd, University Hospital “Virgen de la Arrixaca”, Murcia, Spain
| | - Francisca Alcaraz-Pérez
- Telomerase, Aging and Cancer Group, Research Unit, Department of Surgery, CIBERehd, University Hospital “Virgen de la Arrixaca”, Murcia, Spain
| | - Esther M. García-Navarro
- Telomerase, Aging and Cancer Group, Research Unit, Department of Surgery, CIBERehd, University Hospital “Virgen de la Arrixaca”, Murcia, Spain
| | - María L. Cayuela
- Telomerase, Aging and Cancer Group, Research Unit, Department of Surgery, CIBERehd, University Hospital “Virgen de la Arrixaca”, Murcia, Spain
- * E-mail:
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85
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Vogt N, Gibaud A, Almeida A, Ourliac-Garnier I, Debatisse M, Malfoy B. Relationships linking amplification level to gene over-expression in gliomas. PLoS One 2010; 5:e14249. [PMID: 21170331 PMCID: PMC2999539 DOI: 10.1371/journal.pone.0014249] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 11/12/2010] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Gene amplification is thought to promote over-expression of genes favouring tumour development. Because amplified regions are usually megabase-long, amplification often concerns numerous syntenic or non-syntenic genes, among which only a subset is over-expressed. The rationale for these differences remains poorly understood. METHODOLOGY/PRINCIPAL FINDING To address this question, we used quantitative RT-PCR to determine the expression level of a series of co-amplified genes in five xenografted and one fresh human gliomas. These gliomas were chosen because we have previously characterised in detail the genetic content of their amplicons. In all the cases, the amplified sequences lie on extra-chromosomal DNA molecules, as commonly observed in gliomas. We show here that genes transcribed in non-amplified gliomas are over-expressed when amplified, roughly in proportion to their copy number, while non-expressed genes remain inactive. When specific antibodies were available, we also compared protein expression in amplified and non-amplified tumours. We found that protein accumulation barely correlates with the level of mRNA expression in some of these tumours. CONCLUSIONS/SIGNIFICANCE Here we show that the tissue-specific pattern of gene expression is maintained upon amplification in gliomas. Our study relies on a single type of tumour and a limited number of cases. However, it strongly suggests that, even when amplified, genes that are normally silent in a given cell type play no role in tumour progression. The loose relationships between mRNA level and protein accumulation and/or activity indicate that translational or post-translational events play a key role in fine-tuning the final outcome of amplification in gliomas.
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Affiliation(s)
- Nicolas Vogt
- Institut Curie, Centre de Recherche, Paris, France
- CNRS UMR3244, Paris, France
- UPMC, Paris, France
| | - Anne Gibaud
- Institut Curie, Centre de Recherche, Paris, France
- CNRS UMR3244, Paris, France
- UPMC, Paris, France
| | - Anna Almeida
- Institut Curie, Centre de Recherche, Paris, France
- CNRS UMR3244, Paris, France
- UPMC, Paris, France
| | - Isabelle Ourliac-Garnier
- Institut Curie, Centre de Recherche, Paris, France
- CNRS UMR3244, Paris, France
- UPMC, Paris, France
| | - Michelle Debatisse
- Institut Curie, Centre de Recherche, Paris, France
- CNRS UMR3244, Paris, France
- UPMC, Paris, France
| | - Bernard Malfoy
- Institut Curie, Centre de Recherche, Paris, France
- CNRS UMR3244, Paris, France
- UPMC, Paris, France
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86
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Effects of a growth hormone-releasing hormone antagonist on telomerase activity, oxidative stress, longevity, and aging in mice. Proc Natl Acad Sci U S A 2010; 107:22272-7. [PMID: 21135231 DOI: 10.1073/pnas.1016369107] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Both deficiency and excess of growth hormone (GH) are associated with increased mortality and morbidity. GH replacement in otherwise healthy subjects leads to complications, whereas individuals with isolated GH deficiency such as Laron dwarfs show increased life span. Here, we determined the effects of treatment with the GH-releasing hormone (GHRH) receptor antagonist MZ-5-156 on aging in SAMP8 mice, a strain that develops with aging cognitive deficits and has a shortened life expectancy. Starting at age 10 mo, mice received daily s.c. injections of 10 μg/mouse of MZ-5-156. Mice treated for 4 mo with MZ-5-156 showed increased telomerase activity, improvement in some measures of oxidative stress in brain, and improved pole balance, but no change in muscle strength. MZ-5-156 improved cognition after 2 mo and 4 mo, but not after 7 mo of treatment (ages 12, 14 mo, and 17 mo, respectively). Mean life expectancy increased by 8 wk with no increase in maximal life span, and tumor incidence decreased from 10 to 1.7%. These results show that treatment with a GHRH antagonist has positive effects on some aspects of aging, including an increase in telomerase activity.
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87
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Davies LC, Locke M, Webb RDJ, Roberts JT, Langley M, Thomas DW, Archer CW, Stephens P. A multipotent neural crest-derived progenitor cell population is resident within the oral mucosa lamina propria. Stem Cells Dev 2010; 19:819-30. [PMID: 20132052 DOI: 10.1089/scd.2009.0089] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Wounds within the oral mucosa, similarly to fetal wounds, exhibit rapid healing with reduced scarring. We hypothesized that a progenitor population resident within the oral mucosal lamina propria (OMLP) contributes to this preferential healing. Progenitor cells (PC) were reliably isolated from the OMLP by differential adhesion to fibronectin. Isolated colonies originating from a single cell demonstrated a rapid initial phase of proliferation, completing in excess of 50 population doublings (PDs) before entering cellular senescence. These data were supported by the expression of active telomerase within both developing colonies and expanded clones as assessed by immunocytochemistry (ICC) and the quantitative telomeric repeat amplification protocol. FACS analysis confirmed expression of the stem cell markers CD44, CD90, CD105, and CD166, but negative expression of CD34 and CD45 ruling out a hematopoietic or fibrocyte origin for these progenitors. A neural crest origin was confirmed by increased colony-forming efficiency (CFE) in the presence of Jagged 1 and the expression of a number of neural crest markers within the developing colonies by ICC and serially passaged clones by Western blotting. The multipotency of this novel PC population was demonstrated by differentiation of the cells down both mesenchymal (chondrogenic, osteoblastic, and adipogenic) and neuronal (neuron and Schwann-like cells) cell lineages. This article reports for the first time, the isolation and characterization of a novel, clonally derived PC population resident within the OMLP. The attributes of this adult stem cell (ASC) population and its accessibility lends itself to future therapeutic applications.
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Affiliation(s)
- Lindsay C Davies
- Wound Biology Group, Tissue Engineering and Reparative Dentistry, School of Dentistry, Cardiff University, Heath Park, Cardiff, Wales, United Kingdom
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Berardinelli F, Antoccia A, Cherubini R, De Nadal V, Gerardi S, Cirrone GAP, Tanzarella C, Sgura A. Transient activation of the ALT pathway in human primary fibroblasts exposed to high-LET radiation. Radiat Res 2010; 174:539-49. [PMID: 20726710 DOI: 10.1667/rr2127.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
It is well established that high-LET radiations efficiently induce chromosome aberrations. However, data on the effect of protons on telomere maintenance, as involved in genomic stability, are scarce and contradictory. Here we demonstrate that high-LET protons induce telomere lengthening in human primary fibroblasts and that this elongation does not involve the telomerase enzyme, supporting the hypothesis that high-LET radiations are able to activate a telomerase-independent mechanism. In tumor cells that lack telomerase, one or more non-telomerase mechanisms for telomere maintenance are present, which are termed alternative lengthening of telomeres (ALT). Since ALT cells are characterized by recombinational events at telomeres, known as telomeric-sister chromatid exchanges (T-SCE), and colocalization of telomeres and premyelocytic leukemia protein (PML), we analyzed both T-SCE and PML. Our results show that high-LET protons induce a 2.5-fold increase of T-SCE and a colocalization of PML protein and telomeric DNA. Furthermore, our data show that the ALT pathway can be activated in human primary cells after induction of severe DNA damage. Thus, since telomeres are known to be involved in chromosome maintenance, the present work may contribute in the elucidation of the mechanism by which ionizing radiation induces genomic instability.
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89
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He X, Qiao Q, Ge N, Nan J, Shen S, Wang Z, Yang Y, Bao G. Irradiation-induced telomerase activity and gastric cancer risk: a case-control analysis in a Chinese Han population. BMC Cancer 2010; 10:312. [PMID: 20565943 PMCID: PMC2904282 DOI: 10.1186/1471-2407-10-312] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Accepted: 06/21/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Telomerase expression is one of the characteristics of gastric cancer (GC) cells and telomerase activity is frequently up-regulated by a variety of mechanisms during GC development. Therefore, we hypothesized that elevated levels of activated telomerase might enhance GC risk due to increased propagation of cells with DNA damage, such as induced by gamma-radiation. METHODS To explore this hypothesis, 246 GC cases and 246 matched controls were recruited in our case-control study. TRAP-ELISA was used to assess the levels of telomerase activity at baseline and after gamma-radiation and the gamma-radiation-induced telomerase activity (defined as after gamma-irradiation/baseline) in cultured peripheral blood lymphocytes (PBLs). RESULTS Our data showed that there was no significant difference for the baseline telomerase activity between GC cases and controls (10.17 +/- 7.21 vs. 11.02 +/- 8.03, p = 0.168). However, after gamma-radiation treatment, gamma-radiation-induced telomerase activity was significantly higher in the cases than in the controls (1.51 +/- 0.93 vs. 1.22 +/- 0.66, p < 0.001). Using the median value of gamma-radiation-induced telomerase activity in the controls as a cutoff point, we observed that high gamma-radiation-induced telomerase activity was associated with a significantly increased GC risk (adjusted odds ratio, 2.45; 95% confidence interval, 1.83-3.18). Moreover, a dose response association was noted between gamma-radiation-induced telomerase activity and GC risk. Age, but not sex, smoking and drinking status seem to have a modulating effect on the gamma-radiation-induced telomerase activities in both cases and controls. CONCLUSION Overall, our findings for the first time suggest that the increased gamma-radiation-induced telomerase activity in PBLs might be associated with elevated GC risk. Further confirmation of this association using a prospective study design is warranted.
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Affiliation(s)
- Xianli He
- Department of General Surgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, China
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90
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Lai RC, Arslan F, Tan SS, Tan B, Choo A, Lee MM, Chen TS, Teh BJ, Eng JKL, Sidik H, Tanavde V, Hwang WS, Lee CN, Oakley RME, Pasterkamp G, de Kleijn DP, Tan KH, Lim SK. Derivation and characterization of human fetal MSCs: An alternative cell source for large-scale production of cardioprotective microparticles. J Mol Cell Cardiol 2010; 48:1215-24. [DOI: 10.1016/j.yjmcc.2009.12.021] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 12/15/2009] [Accepted: 12/28/2009] [Indexed: 02/08/2023]
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91
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Assmann G, Werner C, Herrmann M, Momber D, Krenn T, Lothschütz D, Fischer L, Hess S, Ketter R, Feiden W, Jung S, Herrmann W, Schubert J, Pfreundschuh M, Widmann T. Detection of Meningeosis neoplastica by real-time quantitation of telomerase activity. Clin Chem Lab Med 2009; 47:1271-6. [PMID: 19743953 DOI: 10.1515/cclm.2009.258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Analysis of cerebrospinal fluid (CSF) to discriminate between benign and malignant conditions is of fundamental importance for the physician and the patient because of the differential therapeutic options and resulting morbidity and mortality. Most human tumours demonstrate increased telomerase activity (TA). Recent technical advances in the detection of TA allow for sensitive and specific detection within 4 h. Thus, the detection of TA is suitable for routine clinical testing. METHODS This study examines TA in cellular proteins in CSF from 111 patients compared to cytomorphological and laboratory examination. RESULTS A positive result for TA in cellular proteins of CSF was correlated significantly with Meningeosis neoplastica, but not with non-malignant conditions. Telomerase was not detected in CSF supernatant, despite positive results in cellular proteins from identical patients. Furthermore, a 48-h time delay during the pre-analytic processing is not critical for detection of TA detection in native CSF when stored at room temperature. CONCLUSIONS We conclude that TA is a promising marker for the detection of Meningeosis neoplastica and warrants further study.
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Affiliation(s)
- Gunter Assmann
- Klinik und Poliklinik für Innere Medizin I, Universitätsklinikum Homburg, Homburg/Saar, Germany
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92
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Kurvinen K, Rantanen V, Syrjänen S, Johansson B. Radiation-induced effects on telomerase in gynecological cancer cell lines with different radiosensitivity and repair capacity. Int J Radiat Biol 2009; 82:859-67. [PMID: 17178626 DOI: 10.1080/09553000600969812] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE Telomerase activation in response to irradiation might enhance the radioresistance of cells. Thus, we have investigated radiation-induced effects on telomerase in six gynecological cancer cell lines, with different intrinsic radiosensitivity and capacity for sublethal damage repair (SLDR). MATERIALS AND METHODS Three endometrial adenocarcinoma (UM-EC-1, UT-EC-2B and UT-EC-3) and three vulvar squamous cell carcinoma (A431, UM-SCV-2 and UM-SCV-7) cell lines were irradiated with doses of 5, 10 and 25 Gy and the effects on telomerase were evaluated at 0.5, 6, 24 and 48 h post-irradiation. Telomerase activity was quantitatively measured by SYBR Green real-time telomeric repeat amplification protocol. RESULTS The most radioresistant cell line A431 had the strongest stimulatory effects (approximately 2.0 - 2.5-fold) on telomerase activity 24 and 48 h post-irradiation with the highest radiation doses. In contrast to that, telomerase activities in the highly radiosensitive cell line UT-EC-2B remained below the basal level throughout the 48-h period of post-irradiation with the highest doses, and even a decline to approximately 50% of the basal level was found 24 h after exposure. In other cell lines being either moderately or highly radiation resistant, telomerase activity levels in response to irradiation remained mainly at the basal level or gradually increased. CONCLUSIONS The present findings indicate that there might be a connection between the radiation-induced telomerase response and radiosensitivity. However, no correlation was found between the radiation-induced effects on telomerase and the sublethal damage repair capacity of the cells.
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Affiliation(s)
- Kaisa Kurvinen
- Department of Oral Pathology and Oral Radiology, Institute of Dentistry and MediCity Research Laboratory, Faculty of Medicine, University of Turku, Turku, Finland
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Fang JL, Beland FA. Long-term exposure to zidovudine delays cell cycle progression, induces apoptosis, and decreases telomerase activity in human hepatocytes. Toxicol Sci 2009; 111:120-30. [PMID: 19541796 DOI: 10.1093/toxsci/kfp136] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Zidovudine (3'-azido-3'-deoxythymidine; AZT), which is currently used in the treatment of acquired immunodeficiency syndrome, has been shown to have anticancer properties. In the present study, we examined the mechanisms contributing to increased sensitivity of cancer cells to the growth-inhibitory effects of AZT. This was accomplished by incubating a hepatoma cell line (HepG2) and a normal liver cell line (THLE2) with AZT in continuous culture for up to 4 weeks and evaluating the number of viable and necrotic cells, the induction of apoptosis, cell cycle alterations, and telomerase activity. In HepG2 cells, AZT (2-100 microM) caused significant dose-dependent decreases in the number of viable cells at exposures > 24 h. During a 1-week recover period, there was only a slight increase in the number of viable cells treated with AZT. The decrease in viable cells was associated with an induction of apoptosis, a decrease in telomerase activity, and S and G2/M phase arrest of the cell cycle. During the recovery period, the extent of apoptosis and telomerase activity returned to control levels, whereas the disruption of cell cycle progression persisted. Western blot analysis indicated that AZT caused a decrease in checkpoint kinase 1 (Chk1) and kinase 2 (Chk2) and an increase in phosphorylated Chk1 (Ser345) and Chk2 (Thr68). Similar effects, to lesser extent, were observed in THLE2 cells given much higher concentrations of AZT (50-2500 microM). These data show that HepG2 cells are much more sensitive than THLE2 cells to AZT. They also indicate that a combination of a delay of cell cycle progression, an induction of apoptosis, and a decrease in telomerase activity is contributing to the decrease in the number of viable cells from AZT treatment, and that checkpoint enzymes Chk1 and Chk2 may play an important role in the delay of cell cycle progression.
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Affiliation(s)
- Jia-Long Fang
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
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Proctor A, Brownhill SC, Burchill SA. The promise of telomere length, telomerase activity and its regulation in the translocation-dependent cancer ESFT; clinical challenges and utility. Biochim Biophys Acta Mol Basis Dis 2009; 1792:260-74. [PMID: 19264125 DOI: 10.1016/j.bbadis.2009.02.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 02/19/2009] [Accepted: 02/20/2009] [Indexed: 01/12/2023]
Abstract
The Ewing's sarcoma family of tumours (ESFT) are diagnosed by EWS-ETS gene translocations. The resulting fusion proteins play a role in both the initiation and maintenance of these solid aggressive malignant tumours, suppressing cellular senescence and increasing cell proliferation and survival. EWS-ETS fusion proteins have altered transcriptional activity, inducing expression of a number of different target genes including telomerase. Up-regulation of hTERT is most likely responsible for the high levels of telomerase activity in primary ESFT, although telomerase activity and expression of hTERT are not predictive of outcome. However levels of telomerase activity in peripheral blood may be useful to monitor response to some therapeutics. Despite high levels of telomerase activity, telomeres in ESFT are frequently shorter than those of matched normal cells. Uncertainty about the role that telomerase and regulators of its activity play in the maintenance of telomere length in normal and cancer cells, and lack of studies examining the relationship between telomerase activity, regulators of its activity and their clinical significance in patient samples have limited their introduction into clinical practice. Studies in clinical samples using standardised assays are critical to establish how telomerase and regulators of its activity might best be exploited for patient benefit.
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Affiliation(s)
- Andrew Proctor
- Cancer Research UK Clinical Centre, Leeds Institute of Molecular Medicine, St James's University Hospital, Beckett Street, Leeds LS9 7TF, UK
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95
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Abstract
In rheumatoid arthritis (RA), chronically stimulated T lymphocytes sustain tissue-destructive joint inflammation. Both naïve and memory T cells in RA are prematurely aged with accelerated loss of telomeres suggesting excessive proliferative pressure or inadequate telomeric maintenance. Upon stimulation, RA naïve CD4 T cells are defective in up-regulating telomerase activity (P < 0.0001) due to insufficient induction of the telomerase component human telomerase reverse transcriptase (hTERT); T cell activation and cell cycle progression are intact. Telomerase insufficiency does not affect memory T cells or CD34 hematopoietic stem cells and is present in untreated patients and independent from disease activity. Knockdown of hTERT in primary human T cells increases apoptotic propensity (P = 0.00005) and limits clonal burst (P = 0.0001) revealing a direct involvement of telomerase in T cell fate decisions. Naïve RA CD4 T cells stimulated through the T cell receptor are highly susceptible to apoptosis, expanding to smaller clonal size. Overexpression of ectopic hTERT in naïve RA T cells conveys apoptotic resistance (P = 0.008) and restores proliferative expansion (P < 0.0001). Telomerase insufficiency in RA results in excessive T cell loss, undermining homeostatic control of the naive T cell compartment and setting the stage for lymphopenia-induced T cell repertoire remodeling. Restoring defective telomerase activity emerges as a therapeutic target in resetting immune abnormalities in RA.
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96
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Maki CB, Pacchiarotti J, Ramos T, Pascual M, Pham J, Kinjo J, Anorve S, Izadyar F. Phenotypic and molecular characterization of spermatogonial stem cells in adult primate testes. Hum Reprod 2009; 24:1480-91. [PMID: 19246463 DOI: 10.1093/humrep/dep033] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Knowledge about the identity and characteristics of spermatogonial stem cells (SSCs) in human is very limited. Here, Rhesus monkey was used as an animal model to investigate molecular and phenotypic characteristics of SSCs in the adult testes. METHODS A variety of immunohistological, molecular biological and functional assays were used to study different populations of SSCs in the adult testes. RESULTS In adult primate testes, there are distinct populations of CD90+ CD49f+ CD117- (Triple Stained) cells and a small population of stage-specific embryonic antigen-4 (SSEA-4)+ cells which both localized at the basement membrane of seminiferous tubules. Both SSEA-4+ and Triple Stained cells express germ cell and SSC-specific markers and show high telomerase activity; however, only adult Rhesus monkey SSEA-4+ testis cells appear to contain functional and actively dividing SSCs that can repopulate recipient mouse testes following spermatogonial transplantation. DNA analysis of these populations showed that SSEA-4+ cells contain a DNA profile similar to the actively dividing cells, whereas Triple Stained cells showed an accumulated number of cells arrested in the S phase of the cell cycle. SSEA-4+ cells also showed significantly higher proliferation activity, as shown by proliferating cell nuclear antigen staining, than Triple Stained cells (P < 0.01). Interestingly, SSEA-4+ cells expressed a significantly higher level of promyelocytic leukemia zinc finger, a factor required for SSC self-renewal, than Triple Stained cells (P < 0.001). CONCLUSIONS Our data indicate that Triple Stained cells may represent a quiescent population of SSCs, whereas SSEA-4 might be expressed on a subpopulation of actively dividing SSCs.
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Affiliation(s)
- Chad B Maki
- PrimeGen Biotech, 213 Technology Drive, Irvine, CA 92618, USA
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97
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Pickett HA, Cesare AJ, Johnston RL, Neumann AA, Reddel RR. Control of telomere length by a trimming mechanism that involves generation of t-circles. EMBO J 2009; 28:799-809. [PMID: 19214183 PMCID: PMC2670870 DOI: 10.1038/emboj.2009.42] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Accepted: 01/23/2009] [Indexed: 01/09/2023] Open
Abstract
Telomere lengths are maintained in many cancer cells by the ribonucleoprotein enzyme telomerase but can be further elongated by increasing telomerase activity through the overexpression of telomerase components. We report here that increased telomerase activity results in increased telomere length that eventually reaches a plateau, accompanied by the generation of telomere length heterogeneity and the accumulation of extrachromosomal telomeric repeat DNA, principally in the form of telomeric circles (t-circles). Telomeric DNA was observed in promyelocytic leukemia bodies, but no intertelomeric copying or telomere exchange events were identified, and there was no increase in telomere dysfunction-induced foci. These data indicate that human cells possess a mechanism to negatively regulate telomere length by trimming telomeric DNA from the chromosome ends, most likely by t-loop resolution to form t-circles. Additionally, these results indicate that some phenotypic characteristics attributed to alternative lengthening of telomeres (ALT) result from increased mean telomere length, rather than from the ALT mechanism itself.
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Affiliation(s)
- Hilda A Pickett
- Cancer Research Group, Children's Medical Research Institute, Westmead, NSW, Australia
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98
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Chakraborty S, Sun CL, Francisco L, Sabado M, Li L, Chang KL, Forman S, Bhatia S, Bhatia R. Accelerated telomere shortening precedes development of therapy-related myelodysplasia or acute myelogenous leukemia after autologous transplantation for lymphoma. J Clin Oncol 2009; 27:791-8. [PMID: 19124806 DOI: 10.1200/jco.2008.17.1033] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Therapy-related myelodysplasia or acute myelogenous leukemia (t-MDS/AML) is a lethal complication of autologous hematopoietic stem-cell transplantation (aHCT) for Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL). Here, we investigated the hypothesis that accelerated telomere shortening after aHCT could contribute to the development of t-MDS/AML. PATIENTS AND METHODS A prospective longitudinal cohort was constructed to investigate the sequence of cellular and molecular abnormalities leading to development of t-MDS/AML after aHCT for HL/NHL. This cohort formed the sampling frame for a nested case-control study to compare changes in telomere length in serial blood samples from patients who developed t-MDS/AML with matched controls who did not develop t-MDS/AML. RESULTS An initial increase in telomere length at day 100 after aHCT was followed by an accelerated telomere shortening in t-MDS/AML patients when compared with controls. These telomere alterations preceded the onset of t-MDS and were independent of other known risk factors associated with development of t-MDS/AML on multivariate analysis. Additionally, we observed reduced generation of committed progenitors in patients who developed t-MDS/AML, indicating that these telomere alterations were associated with reduced regenerative capacity of hematopoietic stem cells. CONCLUSION The development of t-MDS/AML after aHCT is associated with and preceded by markedly altered telomere dynamics in hematopoietic cells. Accelerated telomere loss in patients developing t-MDS/AML may reflect increased clonal proliferation and/or altered telomere regulation in premalignant cells. Genetic instability associated with shortened telomeres may contribute to leukemic transformation in t-MDS/AML.
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Affiliation(s)
- Sujata Chakraborty
- Department of Stem Cell and Leukemia Research, Division of Population Sciences, City of Hope National Medical Center, Duarte, CA 91010, USA
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Lança V, Zee RY, Rivera A, Romero JR. Quantitative telomerase activity in circulating human leukocytes: utility of real-time telomeric repeats amplification protocol (RQ-TRAP) in a clinical/epidemiological setting. Clin Chem Lab Med 2009; 47:870-3. [DOI: 10.1515/cclm.2009.188] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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100
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Liu L, Ishihara K, Ichimura T, Fujita N, Hino S, Tomita S, Watanabe S, Saitoh N, Ito T, Nakao M. MCAF1/AM is involved in Sp1-mediated maintenance of cancer-associated telomerase activity. J Biol Chem 2008; 284:5165-74. [PMID: 19106100 DOI: 10.1074/jbc.m807098200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Telomerase maintains telomere length and is implicated in senescence and immortalization of mammalian cells. Two essential components for this enzyme are telomerase reverse transcriptase (TERT) and the telomerase RNA component (encoded by the TERC gene). These telomerase subunit genes are known to be mainly expressed by specificity protein 1 (Sp1). MBD1-containing chromatin-associated factor 1 (MCAF1), also known as ATFa-associated modulator (AM) and activating transcription factor 7-interacting protein (ATF7IP), mediates gene regulation, although the precise function of MCAF1 remains to be elucidated. Here, we report that MCAF1 is involved in Sp1-dependent maintenance of telomerase activity in cancer cells. Two evolutionarily conserved domains of MCAF1 directly interact with Sp1 and the general transcriptional apparatus. Selective depletion of MCAF1 or Sp1 down-regulates TERT and TERC genes in cultured cells, which results in decreased telomerase activity. The transcriptionally active form of RNA polymerase II and the general transcription factor ERCC3 decreased in the TERT promoter under the loss of MCAF1 or Sp1. Consistently, MCAF1 is found to be frequently overexpressed in naturally occurring cancers that originate in different tissues. Our data suggest that transcriptional function of MCAF1 facilitates telomerase expression by Sp1, which may be a common mechanism in proliferative cancer cells.
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Affiliation(s)
- Lifeng Liu
- Department of Regeneration Medicine, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Kumamoto 860-0811, Japan
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