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Sameni S, Viswanathan R, Ng GYQ, Martinez-Lopez W, Hande MP. Telomerase Inhibition by MST-312 Sensitizes Breast Cancer Cells to the Anti-cancer Properties of Plumbagin. Genome Integr 2023; 14:e20230002. [PMID: 38765717 PMCID: PMC11102071 DOI: 10.14293/genint.14.1.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024] Open
Abstract
Breast cancer is the most common cause of malignancy and the second most common cause of death due to cancer in women. This heterogeneous disease is currently broadly classified as estrogen receptor (ER), progesterone receptor (PR) positive luminal tumors, human epidermal growth factor receptor 2 (HER2) amplified tumors and triple-negative breast cancers (TNBC). Phytochemicals are proven to be promising anti-cancer chemotherapeutics agents with minimal cytotoxic effects on normal cells. Plumbagin (5-hydroxy-2-methyl-1, 4-naphthoquinone) is a phytochemical derived from the roots of Plumbago zeylanica and it is known to possess anti-cancer properties similar to other compounds of naphthoquinones. In about 90% of cancer cells, the telomerase enzyme activity is revived to add telomeric repeats to evade apoptosis. In this study, a combinatorial approach of combining the anti-cancer compound plumbagin to induce genotoxicity and a potent telomerase inhibitor, MST-312 (synthetic derivative of tea catechins), was used to determine the combinational treatment-induced lethality in breast cancer cells such as MDA-MB-231 (TNBC) and MCF-7 (lumina) cells. MDA-MB-231 cells were responsive to combination treatment in both short-term (48 h) and long-term treatment (14 days) in a synergistic manner, whereas in MCF-7, the combination treatment was more effective in the long-term regimen. Furthermore, the cytotoxic effects of the plumbagin and MST-312 combination treatment were not recoverable after the short-term treatment. In conclusion, a combination treatment of MST-312 and plumbagin is proven to be more effective than a single plumbagin compound treatment in inducing DNA damage and telomere dysfunction leading to greater genome instability, cell cycle arrest and eventually cell death in cancer cells.
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Affiliation(s)
- Safoura Sameni
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Ramya Viswanathan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Gavin Yong-Quan Ng
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Wilner Martinez-Lopez
- Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
- Associate Unit on Genomic Stability, Faculty of Medicine, University of the Republic (UdelaR), Montevideo, Uruguay
| | - M. Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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2
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Dong C, Song C, Chao J, Xiong J, Fang X, Zhang J, Zhu Y, Zhang Y, Wang L. Multi-armed tetrahedral DNA probes for visualizing the whole-course of cell apoptosis by simultaneously fluorescence imaging intracellular cytochrome c and telomerase. Biosens Bioelectron 2022; 205:114059. [DOI: 10.1016/j.bios.2022.114059] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/25/2022] [Accepted: 01/31/2022] [Indexed: 12/24/2022]
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3
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Imran SAM, Yazid MD, Cui W, Lokanathan Y. The Intra- and Extra-Telomeric Role of TRF2 in the DNA Damage Response. Int J Mol Sci 2021; 22:ijms22189900. [PMID: 34576063 PMCID: PMC8470803 DOI: 10.3390/ijms22189900] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 12/12/2022] Open
Abstract
Telomere repeat binding factor 2 (TRF2) has a well-known function at the telomeres, which acts to protect the telomere end from being recognized as a DNA break or from unwanted recombination. This protection mechanism prevents DNA instability from mutation and subsequent severe diseases caused by the changes in DNA, such as cancer. Since TRF2 actively inhibits the DNA damage response factors from recognizing the telomere end as a DNA break, many more studies have also shown its interactions outside of the telomeres. However, very little has been discovered on the mechanisms involved in these interactions. This review aims to discuss the known function of TRF2 and its interaction with the DNA damage response (DDR) factors at both telomeric and non-telomeric regions. In this review, we will summarize recent progress and findings on the interactions between TRF2 and DDR factors at telomeres and outside of telomeres.
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Affiliation(s)
- Siti A. M. Imran
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.)
| | - Muhammad Dain Yazid
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.)
| | - Wei Cui
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK;
| | - Yogeswaran Lokanathan
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.)
- Correspondence: ; Tel.: +603-9145-7704
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Akincilar SC, Chan CHT, Ng QF, Fidan K, Tergaonkar V. Non-canonical roles of canonical telomere binding proteins in cancers. Cell Mol Life Sci 2021; 78:4235-4257. [PMID: 33599797 PMCID: PMC8164586 DOI: 10.1007/s00018-021-03783-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 12/28/2020] [Accepted: 01/29/2021] [Indexed: 02/06/2023]
Abstract
Reactivation of telomerase is a major hallmark observed in 90% of all cancers. Yet paradoxically, enhanced telomerase activity does not correlate with telomere length and cancers often possess short telomeres; suggestive of supplementary non-canonical roles that telomerase might play in the development of cancer. Moreover, studies have shown that aberrant expression of shelterin proteins coupled with their release from shortening telomeres can further promote cancer by mechanisms independent of their telomeric role. While targeting telomerase activity appears to be an attractive therapeutic option, this approach has failed in clinical trials due to undesirable cytotoxic effects on stem cells. To circumvent this concern, an alternative strategy could be to target the molecules involved in the non-canonical functions of telomeric proteins. In this review, we will focus on emerging evidence that has demonstrated the non-canonical roles of telomeric proteins and their impact on tumorigenesis. Furthermore, we aim to address current knowledge gaps in telomeric protein functions and propose future research approaches that can be undertaken to achieve this.
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Affiliation(s)
- Semih Can Akincilar
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Claire Hian Tzer Chan
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Qin Feng Ng
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Kerem Fidan
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Vinay Tergaonkar
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore.
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore.
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5
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Estermann M, Huang YL, Septiadi D, Ritz D, Liang CY, Jacob F, Drasler B, Petri-Fink A, Heinzelmann-Schwarz V, Rothen-Rutishauser B. Patient-derived and artificial ascites have minor effects on MeT-5A mesothelial cells and do not facilitate ovarian cancer cell adhesion. PLoS One 2020; 15:e0241500. [PMID: 33270665 PMCID: PMC7714103 DOI: 10.1371/journal.pone.0241500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 08/07/2020] [Indexed: 12/02/2022] Open
Abstract
The presence of ascites in the peritoneal cavity leads to morphological and functional changes of the peritoneal mesothelial cell layer. Cells loose cell-cell interactions, rearrange their cytoskeleton, activate the production of fibronectin, and change their cell surface morphology in a proinflammatory environment. Moreover, ovarian cancer cell adhesion has been shown to be facilitated by these changes due to increased integrin- and CD44-mediated binding sites. In this study, the biological responsiveness of the human pleural mesothelial cell line MeT-5A to patient-derived and artificial ascites was studied in vitro and adhesion of ovarian cancer cells, i.e. SKOV-3 cells, investigated. Changes were mainly observed in cells exposed to artificial ascites containing higher cytokine concentrations than patient-derived ascites. Interestingly, reduced cell-cell interactions were already observed in untreated MeT-5A cells and effects on tight junction protein expression and permeability upon exposure to ascites were minor. Ascites induced upregulation of CDC42 effector protein 2 expression, which affects stress fiber formation, however significant F-actin reorganization was not observed. Moreover, fibronectin production remained unchanged. Analysis of mesothelial cell surface characteristics showed upregulated expression of intercellular adhesion molecule 1, slightly increased hyaluronic acid secretion and decreased microvillus expression upon exposure to ascites. Nevertheless, the observed changes were not sufficient to facilitate adhesion of SKOV-3 cells on MeT-5A cell layer. This study revealed that MeT-5A cells show a reduced biological responsiveness to the presence of ascites, in contrast to published studies on primary human peritoneal mesothelial cells.
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Affiliation(s)
- Manuela Estermann
- Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland
| | - Yen-Lin Huang
- Department of Biomedicine, University Hospital Basel and University of Basel, Basel, Switzerland
| | - Dedy Septiadi
- Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland
| | - Danilo Ritz
- Proteomics Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Ching-Yeu Liang
- Department of Biomedicine, University Hospital Basel and University of Basel, Basel, Switzerland
| | - Francis Jacob
- Department of Biomedicine, University Hospital Basel and University of Basel, Basel, Switzerland
| | - Barbara Drasler
- Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland
| | - Alke Petri-Fink
- Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland
- Department of Chemistry, University of Fribourg, Fribourg, Switzerland
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Pereira CD, Martins F, Santos M, Müeller T, da Cruz e Silva OAB, Rebelo S. Nuclear Accumulation of LAP1:TRF2 Complex during DNA Damage Response Uncovers a Novel Role for LAP1. Cells 2020; 9:E1804. [PMID: 32751253 PMCID: PMC7465990 DOI: 10.3390/cells9081804] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/10/2020] [Accepted: 07/28/2020] [Indexed: 02/06/2023] Open
Abstract
Lamina-associated polypeptide 1 (LAP1) is a nuclear envelope (NE) protein whose function remains poorly characterized. In a recent LAP1 protein interactome study, a putative regulatory role in the DNA damage response (DDR) has emerged and telomeric repeat-binding factor 2 (TRF2), a protein intimately associated with this signaling pathway, was among the list of LAP1 interactors. To gain insights into LAP1's physiological properties, the interaction with TRF2 in human cells exposed to DNA-damaging agents was investigated. The direct LAP1:TRF2 binding was validated in vitro by blot overlay and in vivo by co-immunoprecipitation after hydrogen peroxide and bleomycin treatments. The regulation of this protein interaction by LAP1 phosphorylation was demonstrated by co-immunoprecipitation and mass spectrometry following okadaic acid exposure. The involvement of LAP1 and TRF2 in the DDR was confirmed by their increased nuclear protein levels after bleomycin treatment, evaluated by immunoblotting, as well as by their co-localization with DDR factors at the NE and within the nucleoplasm, assessed by immunocytochemistry. Effectively, we showed that the LAP1:TRF2 complex is established during a cellular response against DNA damage. This work proposes a novel functional role for LAP1 in the DDR, revealing a potential biological mechanism that may be disrupted in LAP1-associated pathologies.
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Affiliation(s)
- Cátia D. Pereira
- Neuroscience and Signaling Laboratory, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal; (C.D.P.); (F.M.); (M.S.); (O.A.B.d.C.eS.)
| | - Filipa Martins
- Neuroscience and Signaling Laboratory, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal; (C.D.P.); (F.M.); (M.S.); (O.A.B.d.C.eS.)
| | - Mariana Santos
- Neuroscience and Signaling Laboratory, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal; (C.D.P.); (F.M.); (M.S.); (O.A.B.d.C.eS.)
| | - Thorsten Müeller
- Cell Signaling in Neurodegeneration (CSIN), Medical Proteome-Center, Ruhr-University Bochum, 44801 Bochum, Germany;
| | - Odete A. B. da Cruz e Silva
- Neuroscience and Signaling Laboratory, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal; (C.D.P.); (F.M.); (M.S.); (O.A.B.d.C.eS.)
| | - Sandra Rebelo
- Neuroscience and Signaling Laboratory, Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal; (C.D.P.); (F.M.); (M.S.); (O.A.B.d.C.eS.)
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7
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Oh BK, Choi Y, Bae J, Lee WM, Hoh JK, Choi JS. Increased amounts and stability of telomeric repeat-containing RNA (TERRA) following DNA damage induced by etoposide. PLoS One 2019; 14:e0225302. [PMID: 31756221 PMCID: PMC6874320 DOI: 10.1371/journal.pone.0225302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 11/01/2019] [Indexed: 11/25/2022] Open
Abstract
Telomeric repeat-containing RNAs (TERRAs) are long noncoding RNAs transcribed from subtelomeres toward telomeric repeat tracts, which have been implicated in telomere protection and heterochromatin formation. Genotoxic stress leads to upregulation of TERRAs. However, the mechanism of DNA damage-mediated TERRA induction remains elusive. Here, we treated HeLa cells with etoposide, a DNA double-strand break-generating agent, for various times and monitored the levels of TERRAs. Etoposide treatment led to a gradual time-dependent increase in TERRAs. Etoposide-mediated induction was evident in many TERRAs arising from various chromosome loci, including 20q and XpYp. Chromatin immunoprecipitation assays revealed no significant changes in the occupancy of RNA polymerase II at telomeres upon etoposide treatment. Interestingly, TERRAs arising from 20q, XpYp, 10q, and 13q degraded at slower rates in cells treated with etoposide, while degradation rates of TERRAs from many loci tested were nearly identical in both etoposide- and mock-treated cells. Telomere damage occurred from early time points of etoposide treatment, but telomere lengths and abundance of telomeric repeat-binding factor 2 (TRF2) at telomeres remained unchanged. In summary, etoposide treatment led to telomere damage and TERRA accumulation, but telomere lengths and TRF2-mediated telomere integrity were maintained. Etoposide-mediated TERRA accumulation could be attributed partly to RNA stabilization. These findings may provide insight into the post-transcriptional regulation of TERRAs in response to DNA damage.
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MESH Headings
- Antineoplastic Agents, Phytogenic/adverse effects
- Cell Survival/drug effects
- Chromosomes, Human, Pair 20/genetics
- Chromosomes, Human, X/genetics
- Chromosomes, Human, Y/genetics
- DNA Damage
- Etoposide/adverse effects
- Gene Expression Regulation, Neoplastic/drug effects
- HeLa Cells
- Humans
- RNA Stability
- RNA, Long Noncoding/chemistry
- RNA, Long Noncoding/genetics
- Telomere/drug effects
- Telomere/genetics
- Telomeric Repeat Binding Protein 2
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Affiliation(s)
- Bong-Kyeong Oh
- Institute for the Integration of Medicine and Innovative Technology, Hanyang University College of Medicine, Seoul, Korea
| | - Yoojung Choi
- Department of Translational Medicine, Hanyang University Graduate School of Biomedical Science and Engineering, Seoul, Korea
| | - Jaeman Bae
- Department of Obstetrics and Gynecology, Hanyang University College of Medicine, Seoul, Korea
| | - Won Moo Lee
- Department of Obstetrics and Gynecology, Hanyang University College of Medicine, Seoul, Korea
| | - Jeong-Kyu Hoh
- Department of Obstetrics and Gynecology, Hanyang University College of Medicine, Seoul, Korea
| | - Joong Sub Choi
- Institute for the Integration of Medicine and Innovative Technology, Hanyang University College of Medicine, Seoul, Korea
- Department of Obstetrics and Gynecology, Hanyang University College of Medicine, Seoul, Korea
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8
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Dilshara MG, Jayasooriya RGPT, Choi YH, Kim GY. Camptothecin induces c-Myc- and Sp1-mediated hTERT expression in LNCaP cells: Involvement of reactive oxygen species and PI3K/Akt. Food Chem Toxicol 2019; 127:53-60. [PMID: 30851366 DOI: 10.1016/j.fct.2019.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Revised: 02/14/2019] [Accepted: 03/01/2019] [Indexed: 01/08/2023]
Abstract
Camptothecin (CPT), a quinoline alkaloid isolated from Camptotheca acuminate, targets topoisomerase I, which is continuously expressed in cancer cells. However, the molecular mechanisms responsible for CPT-induced telomerase inhibition remain unclear. Unexpectedly, we found that CPT upregulates hTERT expression and concomitantly increases telomerase activity. However, transfection of hTERT-targeting siRNA had no effect on CPT-induced G2/M phase arrest, suggesting that CPT-induced telomerase activation was not related to G2/M phase arrest. CPT simultaneously increased Nrf2 expression and the level of intracellular reactive oxygen species (ROS), whereas pretreatment with the antioxidants N-acetyl-cysteine (NAC) or glutathione (GSH) strongly attenuated ROS production, which was accompanied by hTERT downregulation. Additionally, transient Nrf2 knockdown enhanced CPT-induced ROS production and hTERT promoter activity. CPT also upregulated hTERT expression and telomerase activity by inducing c-Myc and Sp1 expression and activity. Moreover, c-Myc stimulated ROS production in response to CPT, leading to Sp1 activation, which promoted hTERT expression and telomerase activity. CPT treatment enhanced the phosphorylation of PI3K and Akt, which led to hTERT phosphorylation into the nucleus. These findings demonstrate that CPT positively regulates telomerase activity by upregulating hTERT expression and phosphorylation via the c-Myc/ROS/Sp1 and PI3K/Akt axis.
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Affiliation(s)
| | | | - Yung Hyun Choi
- Department of Biochemistry, College of Oriental Medicine, Dong-Eui University, Busan 47227, Republic of Korea
| | - Gi-Young Kim
- Department of Marine Life Sciences, Jeju National University, Jeju 63243, Republic of Korea.
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9
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Shariati M, Hajigholami S, Veisi Malekshahi Z, Entezari M, Bodaghabadi N, Sadeghizadeh M. Nanocurcumin-Mediated Down-Regulation of Telomerase Via Stimulating TGFβ1 Signaling Pathway in Hepatocellular Carcinoma Cells. IRANIAN BIOMEDICAL JOURNAL 2018; 22:171-9. [PMID: 28992682 PMCID: PMC5889502 DOI: 10.22034/ibj.22.3.171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Background Curcumin, extracted from turmeric, represents enormous potential to serve as an anticancer agent. Telomerase is viewed as a prominent molecular target of curcumin, and Transforming growth factor-β1 (TGFβ1) has proven to be a major inhibitory signaling pathway for telomerase activity. In the current study, we aimed to explore suppressive effects of nanocurcumin on telomerase expression through TGFβ1 pathway in a hepatocellular carcinoma cell line (Huh7). Methods MTT assay was used to determine the effect of nonocurcumin on viability of Huh7 cells. RT-PCR was used to analyze the gene expression patterns. Results MTT assay revealed that nanocurcumin acts in a dose- and time-dependent manner to diminish the cell viability.
RT-PCR analysis indicated that nanocurcumin results in augmentation of TGFβ1 72 hours post treatment and leads to the reduction of telomerase expression 48 and 72 hours post exposure. Also, up-regulation of Smad3 and E2F1 and down-regulation of Smad7 confirmed the effect of nanocurcumin on intermediate components of TGFβ1 pathway. Furthermore, transfection of the proximal promoter of telomerase triggered a significant reduction in luciferase activity. Conclusion The data from the present study lead us to develop a deeper understanding of the mechanisms underlying nanocurcumin-mediated regulation of telomerase expression, thereby presenting a new perspective to the landscape of using nanocurcumin as a cancer-oriented therapeutic agent.
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Affiliation(s)
- Molood Shariati
- Department of Molecular Genetics, School of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-154, Tehran, Iran
| | - Samira Hajigholami
- Department of Molecular Genetics, School of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-154, Tehran, Iran
| | - Ziba Veisi Malekshahi
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Maliheh Entezari
- Department of Biology, Islamic Azad University, Tehran Medical Sciences Branch, Tehran, Iran
| | - Narges Bodaghabadi
- Department of Molecular Genetics, School of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-154, Tehran, Iran
| | - Majid Sadeghizadeh
- Department of Molecular Genetics, School of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-154, Tehran, Iran
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10
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Moro-García MA, Mayo JC, Sainz RM, Alonso-Arias R. Influence of Inflammation in the Process of T Lymphocyte Differentiation: Proliferative, Metabolic, and Oxidative Changes. Front Immunol 2018; 9:339. [PMID: 29545794 PMCID: PMC5839096 DOI: 10.3389/fimmu.2018.00339] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 02/06/2018] [Indexed: 01/02/2023] Open
Abstract
T lymphocytes, from their first encounter with their specific antigen as naïve cell until the last stages of their differentiation, in a replicative state of senescence, go through a series of phases. In several of these stages, T lymphocytes are subjected to exponential growth in successive encounters with the same antigen. This entire process occurs throughout the life of a human individual and, earlier, in patients with chronic infections/pathologies through inflammatory mediators, first acutely and later in a chronic form. This process plays a fundamental role in amplifying the activating signals on T lymphocytes and directing their clonal proliferation. The mechanisms that control cell growth are high levels of telomerase activity and maintenance of telomeric length that are far superior to other cell types, as well as metabolic adaptation and redox control. Large numbers of highly differentiated memory cells are accumulated in the immunological niches where they will contribute in a significant way to increase the levels of inflammatory mediators that will perpetuate the new state at the systemic level. These levels of inflammation greatly influence the process of T lymphocyte differentiation from naïve T lymphocyte, even before, until the arrival of exhaustion or cell death. The changes observed during lymphocyte differentiation are correlated with changes in cellular metabolism and these in turn are influenced by the inflammatory state of the environment where the cell is located. Reactive oxygen species (ROS) exert a dual action in the population of T lymphocytes. Exposure to high levels of ROS decreases the capacity of activation and T lymphocyte proliferation; however, intermediate levels of oxidation are necessary for the lymphocyte activation, differentiation, and effector functions. In conclusion, we can affirm that the inflammatory levels in the environment greatly influence the differentiation and activity of T lymphocyte populations. However, little is known about the mechanisms involved in these processes. The elucidation of these mechanisms would be of great help in the advance of improvements in pathologies with a large inflammatory base such as rheumatoid arthritis, intestinal inflammatory diseases, several infectious diseases and even, cancerous processes.
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Affiliation(s)
- Marco A Moro-García
- Department of Immunology, Hospital Universitario Central de Asturias (HUCA), Oviedo, Spain
| | - Juan C Mayo
- Department of Morphology and Cell Biology, Institute of Oncology of Asturias (IUOPA), University of Oviedo, Oviedo, Spain
| | - Rosa M Sainz
- Department of Morphology and Cell Biology, Institute of Oncology of Asturias (IUOPA), University of Oviedo, Oviedo, Spain
| | - Rebeca Alonso-Arias
- Department of Immunology, Hospital Universitario Central de Asturias (HUCA), Oviedo, Spain.,Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
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11
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Benhamou Y, Picco V, Raybaud H, Sudaka A, Chamorey E, Brolih S, Monteverde M, Merlano M, Lo Nigro C, Ambrosetti D, Pagès G. Telomeric repeat-binding factor 2: a marker for survival and anti-EGFR efficacy in oral carcinoma. Oncotarget 2018; 7:44236-44251. [PMID: 27329590 PMCID: PMC5190092 DOI: 10.18632/oncotarget.10005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 05/04/2016] [Indexed: 12/21/2022] Open
Abstract
Oral Squamous Cell Carcinoma (OSCC) is the most common oral cancer worldwide. Treatments including surgery, radio- and chemo-therapies mostly result in debilitating side effects. Thus, a more accurate evaluation of patients at risk of recurrence after radio/chemo treatment is important for preserving their quality of life. We assessed whether the Telomeric Repeat-binding Factor 2 (TERF2) influences tumor aggressiveness and treatment response. TERF2 is over-expressed in many cancers but its correlation to patient outcome remains controversial in OSCC. Our retrospective study on sixty-two patients showed that TERF2 overexpression has a negative impact on survival time. TERF2-dependent survival time was independent of tumor size in a multivariate analysis. In vitro, TERF2 knockdown by RNA interference had no effect on cell proliferation, migration, senescence and apoptosis. Instead, TERF2 knockdown increased the expression of cytokines implicated in inflammation and angiogenesis, except for vascular endothelial growth factor. TERF2 knockdown resulted in a decrease vascularization and growth of xenograft tumors. Finally, response to erlotinib/Tarceva and cetuximab/Erbitux treatment was increased in TRF2 knocked-down cells. Hence, TERF2 may represent an independent marker of survival for OSCC and a predictive marker for cetuximab/Erbitux and erlotinib/Tarceva efficacy.
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Affiliation(s)
- Yordan Benhamou
- CNRS UMR 7284/INSERM U1081, Institute for Research on Cancer and Aging of Nice, University of Nice Sophia Antipolis, Nice, France.,Odontology Department, Nice University Hospital, University of Nice Sophia Antipolis, Nice, France
| | - Vincent Picco
- Biomedical Department, Centre Scientifique de Monaco, Principality of Monaco
| | - Hélène Raybaud
- Central Laboratory of Pathology, University of Nice Sophia Antipolis, Nice, France
| | - Anne Sudaka
- Department of Pathology, Research and Statistics, Centre Antoine Lacassagne, Nice, France
| | - Emmanuel Chamorey
- Department of Pathology, Research and Statistics, Centre Antoine Lacassagne, Nice, France
| | - Sanja Brolih
- Biomedical Department, Centre Scientifique de Monaco, Principality of Monaco
| | - Martino Monteverde
- Cancer Genetics and Translational Oncology Laboratory, S. Croce & Carle Teaching Hospital, Cuneo, Italy
| | - Marco Merlano
- Medical Oncology, Oncology Department, S. Croce & Carle Teaching Hospital, Cuneo, Italy
| | - Cristiana Lo Nigro
- Cancer Genetics and Translational Oncology Laboratory, S. Croce & Carle Teaching Hospital, Cuneo, Italy
| | - Damien Ambrosetti
- Central Laboratory of Pathology, University of Nice Sophia Antipolis, Nice, France
| | - Gilles Pagès
- CNRS UMR 7284/INSERM U1081, Institute for Research on Cancer and Aging of Nice, University of Nice Sophia Antipolis, Nice, France
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12
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Chhabra G, Wojdyla L, Frakes M, Schrank Z, Leviskas B, Ivancich M, Vinay P, Ganapathy R, Ramirez BE, Puri N. Mechanism of Action of G-Quadruplex-Forming Oligonucleotide Homologous to the Telomere Overhang in Melanoma. J Invest Dermatol 2017; 138:903-910. [PMID: 29203363 DOI: 10.1016/j.jid.2017.11.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 11/09/2017] [Accepted: 11/13/2017] [Indexed: 12/19/2022]
Abstract
T-oligo, a guanine-rich oligonucleotide homologous to the 3'-telomeric overhang of telomeres, elicits potent DNA-damage responses in melanoma cells; however, its mechanism of action is largely unknown. Guanine-rich oligonucleotides can form G-quadruplexes (G4), which are stabilized by the hydrogen bonding of guanine residues. In this study, we confirmed the G4-forming capabilities of T-oligo using nondenaturing PAGE, nuclear magnetic resonance, and immunofluorescence. Using an anti-G-quadruplex antibody, we showed that T-oligo can form G4 in the nuclei of melanoma cells. Furthermore, using DNase I in a nuclease degradation assay, G4-T-oligo was found to be more stable than single-stranded T-oligo. G4-T-oligo had decreased antiproliferative effects compared with single-stranded T-oligo. However, G4-T-oligo has similar cellular uptake as single-stranded T-oligo, as shown by FACS analysis. Inhibition of JNK, which causes DNA damage-induced apoptosis, partially reversed the antiproliferative activity of T-oligo. T-oligo also inhibited mRNA expression of human telomerase reverse transcriptase, a catalytic subunit of telomerase that was reversed by JNK inhibition. Furthermore, two shelterin complex proteins TRF2/POT1 were found to be up-regulated and bound by T-oligo, suggesting that T-oligo may mediate dissociation of these proteins from the telomere overhang. These studies show that T-oligo can form a G-quadruplex and that the antitumor effects of T-oligo may be mediated through POT1/TRF2 and via human telomerase reverse transcriptase inhibition through JNK activation.
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Affiliation(s)
- Gagan Chhabra
- University of Illinois College of Medicine at Rockford, Rockford, Illinois, USA
| | - Luke Wojdyla
- University of Illinois College of Medicine at Rockford, Rockford, Illinois, USA
| | - Mark Frakes
- University of Illinois College of Medicine at Rockford, Rockford, Illinois, USA
| | - Zachary Schrank
- University of Illinois College of Medicine at Rockford, Rockford, Illinois, USA
| | - Brandon Leviskas
- University of Illinois College of Medicine at Rockford, Rockford, Illinois, USA
| | - Marko Ivancich
- University of Illinois College of Medicine at Rockford, Rockford, Illinois, USA
| | - Pooja Vinay
- University of Illinois College of Medicine at Rockford, Rockford, Illinois, USA
| | | | - Benjamin E Ramirez
- Center for Structural Biology, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Neelu Puri
- University of Illinois College of Medicine at Rockford, Rockford, Illinois, USA.
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13
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Abstract
The increased level of chromosome instability in cancer cells, leading to aneuploidy and gross chromosomal rearrangements, is not only a driving force for oncogenesis but also can be the Achille's heel of the disease since many chemotherapies (CT) kill cells by inducing a non-tolerable rate of DNA damage. A wealth of published evidence showed that telomere stability can be more affected than the bulk of the genome by several conventional antineoplasic drugs. These results raise the interesting possibility that CT with genotoxic drugs preferentially target telomeres. In agreement with this view, accelerated shortening of telomere length has been described in blood lineage cells following high-dose CT (stem cell transplantation) or non-myeloablative CT. However, almost nothing is known on the consequences of this shortening in terms of telomere stability, senescence and on the development of second cancers or post-treatment aging-like syndromes in cancer survivors (cognitive defect, fertility impairment, etc.). In this article, we propose: (1) telomeres of cancer cells are preferential genomic targets of chemotherapies altering chromosome maintenance; (2) telomere functional parameters can be a surrogate marker of chemotherapy sensitivity and toxicity; (3) the use of anti-telomere molecule could greatly enhance the sensitivity to standards chemotherapies.
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14
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Moro-García MA, Alonso-Arias R, López-Larrea C. Molecular mechanisms involved in the aging of the T-cell immune response. Curr Genomics 2013; 13:589-602. [PMID: 23730199 PMCID: PMC3492799 DOI: 10.2174/138920212803759749] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 08/28/2012] [Accepted: 08/31/2012] [Indexed: 12/24/2022] Open
Abstract
T-lymphocytes play a central role in the effector and regulatory mechanisms of the adaptive immune response. Upon exiting the thymus they begin to undergo a series of phenotypic and functional changes that continue throughout the lifetime and being most pronounced in the elderly. The reason postulated for this is that the dynamic processes of repeated interaction with cognate antigens lead to multiple division cycles involving a high degree of cell differentiation, senescence, restriction of the T-cell receptor (TCR) repertoire, and cell cycle arrest. This cell cycle arrest is associated with the loss of telomere sequences from the ends of chromosomes. Telomere length is reduced at each cell cycle, and critically short telomeres recruit components of the DNA repair machinery and trigger replicative senescence or apoptosis. Repetitively stimulated T-cells become refractory to telomerase induction, suffer telomere erosion and enter replicative senescence. The latter is characterized by the accumulation of highly differentiated T-cells with new acquired functional capabilities, which can be caused by aberrant expression of genes normally suppressed by epigenetic mechanisms in CD4+ or CD8+ T-cells. Age-dependent demethylation and overexpression of genes normally suppressed by DNA methylation have been demonstrated in senescent subsets of T-lymphocytes. Thus, T-cells, principally CD4+CD28null T-cells, aberrantly express genes, including those of the KIR gene family and cytotoxic proteins such as perforin, and overexpress CD70, IFN-γ, LFA-1 and others. In summary, owing to a lifetime of exposure to and proliferation against a variety of pathogens, highly differentiated T-cells suffer molecular modifications that alter their cellular homeostasis mechanisms.
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15
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Moro-García MA, Alonso-Arias R, López-Larrea C. When Aging Reaches CD4+ T-Cells: Phenotypic and Functional Changes. Front Immunol 2013; 4:107. [PMID: 23675374 PMCID: PMC3650461 DOI: 10.3389/fimmu.2013.00107] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 04/25/2013] [Indexed: 12/30/2022] Open
Abstract
Beyond midlife, the immune system shows aging features and its defensive capability becomes impaired, by a process known as immunosenescence that involves many changes in the innate and adaptive responses. Innate immunity seems to be better preserved globally, while the adaptive immune response exhibits profound age-dependent modifications. Elderly people display a decline in numbers of naïve T-cells in peripheral blood and lymphoid tissues, while, in contrast, their proportion of highly differentiated effector and memory T-cells, such as the CD28null T-cells, increases markedly. Naïve and memory CD4+ T-cells constitute a highly dynamic system with constant homeostatic and antigen-driven proliferation, influx, and loss of T-cells. Thymic activity dwindles with age and essentially ceases in the later decades of life, severely constraining the generation of new T-cells. Homeostatic control mechanisms are very effective at maintaining a large and diverse subset of naïve CD4+ T-cells throughout life, but although later than in CD8 + T-cell compartment, these mechanisms ultimately fail with age.
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16
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hTERT: Another brick in the wall of cancer cells. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2013; 752:119-128. [DOI: 10.1016/j.mrrev.2012.12.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 11/28/2012] [Accepted: 12/10/2012] [Indexed: 01/06/2023]
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17
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Giraud-Panis MJ, Pisano S, Benarroch-Popivker D, Pei B, Le Du MH, Gilson E. One identity or more for telomeres? Front Oncol 2013; 3:48. [PMID: 23509004 PMCID: PMC3598436 DOI: 10.3389/fonc.2013.00048] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Accepted: 02/23/2013] [Indexed: 12/19/2022] Open
Abstract
A major issue in telomere research is to understand how the integrity of chromosome ends is controlled. The fact that different types of nucleoprotein complexes have been described at the telomeres of different organisms raises the question of whether they have in common a structural identity that explains their role in chromosome protection. We will review here how telomeric nucleoprotein complexes are structured, comparing different organisms and trying to link these structures to telomere biology. It emerges that telomeres are formed by a complex and specific network of interactions between DNA, RNA, and proteins. The fact that these interactions and associated activities are reinforcing each other might help to guarantee the robustness of telomeric functions across the cell cycle and in the event of cellular perturbations. We will also discuss the recent notion that telomeres have evolved specific systems to overcome the DNA topological stress generated during their replication and transcription. This will lead to revisit the way we envisage the functioning of telomeric complexes since the regulation of topology is central to DNA stability, replication, recombination, and transcription as well as to chromosome higher-order organization.
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Affiliation(s)
- Marie-Josèphe Giraud-Panis
- Faculté de Médecine de Nice, Université de Nice-Sophia Antipolis, Institute for Research on Cancer and Aging Nice, UMR 7284 CNRS, U1081 INSERM Nice, France
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18
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The MAPK pathway signals telomerase modulation in response to isothiocyanate-induced DNA damage of human liver cancer cells. PLoS One 2013; 8:e53240. [PMID: 23382840 PMCID: PMC3561400 DOI: 10.1371/journal.pone.0053240] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 11/27/2012] [Indexed: 11/19/2022] Open
Abstract
4-methylthiobutyl isothiocyanate (MTBITC), an aliphatic, sulphuric compound from Brassica vegetables, possesses in vitro and in vivo antitumor activity. Recently we demonstrated the potent growth inhibitory potential of the DNA damaging agent MTBITC in human liver cancer cells. Here we now show that MTBITC down regulates telomerase which sensitizes cells to apoptosis induction. This is mediated by MAPK activation but independent from production of reactive oxygen species (ROS). Within one hour, MTBITC induced DNA damage in cancer cells correlating to a transient increase in hTERT mRNA expression which then turned into telomerase suppression, evident at mRNA as well as enzyme activity level. To clarify the role of MAPK for telomerase regulation, liver cancer cells were pre-treated with MAPK-specific inhibitors prior to MTBITC exposure. This clearly showed that transient elevation of hTERT mRNA expression was predominantly mediated by the MAPK family member JNK. In contrast, activated ERK1/2 and P38, but not JNK, signalled to telomerase abrogation and consequent apoptosis induction. DNA damage by MTBITC was also strongly abolished by MAPK inhibition. Oxidative stress, as analysed by DCF fluorescence assay, electron spin resonance spectroscopy and formation of 4-hydroxynonenal was found as not relevant for this process. Furthermore, N-acetylcysteine pre-treatment did not impact MTBITC-induced telomerase suppression or depolarization of the mitochondrial membrane potential as marker for apoptosis. Our data therefore imply that upon DNA damage by MTBITC, MAPK are essential for telomerase regulation and consequent growth impairment in liver tumor cells and this detail probably plays an important role in understanding the potential chemotherapeutic efficacy of ITC.
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19
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Chuang HC, Chen CH, Huang CC, Fang FM, Tsai HT, Chien CY. Reduced expression of TRF1 is associated with tumor progression and poor prognosis in oral squamous cell carcinoma. Exp Ther Med 2010; 2:63-67. [PMID: 22977470 PMCID: PMC3440641 DOI: 10.3892/etm.2010.168] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 11/19/2010] [Indexed: 12/15/2022] Open
Abstract
The functions of telomeric repeat-binding factor 1 (TRF1) and 2 (TRF2) in oral carcinogenesis are largely unexplored. This study examined the relationship between the expression of TRF1 and TRF2 and clinicopathological variables and survival in oral cavity squamous cell carcinoma (OCSCC). Western blotting and immunohistochemistry were used to evaluate the protein expression of TRF1 and TRF2 in paired OCSCC patient specimens. Expression of TRF1 and TRF2 was assessed by immunohistochemistry in 256 OCSCC patients who underwent tumor resection without previous radiotherapy. The results were analyzed using Fisher's exact test. Protein expression of TRF1 and TRF2 was significantly lower in the OCSCC than in the adjacent non-tumor tissue. Reduced TRF1 and TRF2 levels in 256 patients, as revealed by immunohistochemistry, were significantly associated with aggressive clinicopathological features, such as advanced tumor stage (p<0.001) and advanced tumor node metastasis stage (p<0.001). According to Kaplan-Meier analysis, reduced TRF1 expression was significantly correlated with an unfavorable cumulative 5-year overall survival rate (p<0.001). In conclusion, decreased expression of TRF1 was significantly associated with tumor progression and poor prognosis in OCSCC patients.
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20
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Kavitha CV, Choudhary B, Raghavan SC, Muniyappa K. Differential regulation of MRN (Mre11-Rad50-Nbs1) complex subunits and telomerase activity in cancer cells. Biochem Biophys Res Commun 2010; 399:575-80. [PMID: 20682289 DOI: 10.1016/j.bbrc.2010.07.117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 07/29/2010] [Indexed: 11/26/2022]
Abstract
Several lines of evidence suggest that cancer progression is associated with up-regulation or reactivation of telomerase and the underlying mechanism remains an active area of research. The heterotrimeric MRN complex, consisting of Mre11, Rad50 and Nbs1, which is required for the repair of double-strand breaks, plays a key role in telomere length maintenance. In this study, we show significant differences in the levels of expression of MRN complex subunits among various cancer cells and somatic cells. Notably, siRNA-mediated depletion of any of the subunits of MRN complex led to complete ablation of other subunits of the complex. Treatment of leukemia and prostate cancer cells with etoposide lead to increased expression of MRN complex subunits, with concomitant decrease in the levels of telomerase activity, compared to breast cancer cells. These studies raise the possibility of developing anti-cancer drugs targeting MRN complex subunits to sensitize a subset of cancer cells to radio- and/or chemotherapy.
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Affiliation(s)
- C V Kavitha
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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21
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Deregulation of the telomerase reverse transcriptase (TERT) gene by chromosomal translocations in B-cell malignancies. Blood 2010; 116:1317-20. [PMID: 20460502 DOI: 10.1182/blood-2009-09-240440] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Sequence variants at the TERT-CLPTM1L locus in chromosome 5p have been recently associated with disposition for various cancers. Here we show that this locus including the gene encoding the telomerase reverse-transcriptase TERT at 5p13.33 is rarely but recurrently targeted by somatic chromosomal translocations to IGH and non-IG loci in B-cell neoplasms, including acute lymphoblastic leukemia, chronic lymphocytic leukemia, mantle cell lymphoma and splenic marginal zone lymphoma. In addition, cases with genomic amplification of TERT locus were identified. Tumors bearing chromosomal aberrations involving TERT showed higher TERT transcriptional expression and increased telomerase activity. These data suggest that deregulation of TERT gene by chromosomal abnormalities leading to increased telomerase activity might contribute to B-cell lymphomagenesis.
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22
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Ram R, Uziel O, Eldan O, Fenig E, Beery E, Lichtenberg S, Nordenberg Y, Lahav M. Ionizing radiation up-regulates telomerase activity in cancer cell lines by post-translational mechanism via ras/phosphatidylinositol 3-kinase/Akt pathway. Clin Cancer Res 2009; 15:914-23. [PMID: 19188162 DOI: 10.1158/1078-0432.ccr-08-0792] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Telomerase is considered currently as a hallmark of cancer, and its inhibition is expected to become an important anticancer modality. In contrast to abundant data concerning the effect of cytotoxic drugs on telomerase activity (TA), there is scant information on the effect of radiation on telomerase. The mechanism of telomerase regulation by irradiation has never been evaluated in detail. In the present study, we investigated the effect of radiation on TA and its regulation in cancer cells. EXPERIMENTAL DESIGN The effect of various radiation doses on TA in several malignant and nonmalignant cell lines was evaluated. All malignant cells exhibited similar telomerase response to radiation and its regulation was assessed at transcriptional and post-translational levels in K562 cells. Next step was the evaluation of the upstream signaling pathways leading to changes in TA using kinetics and specific inhibitors. RESULTS Radiation up-regulated TA in dose-dependent manner only in cancer cells. Telomerase was activated by phosphorylation by Akt and by cytoplasmic-nuclear shift. Transcriptional processes were not involved in TA. This telomerase regulation is mediated by Ras/phosphatidylinositol 3-kinase/Akt pathway. The canonical membrane effectors of irradiation (epidermal growth factor receptor, insulin-like growth factor-I receptor, and Ca2+ influx) were not involved in this process. CONCLUSIONS Radiation up-regulates telomerase activity specifically in cancer cells. This study adds to accumulating evidence pointing to post-translational level as important mode of telomerase regulation. Telomerase activation due to radiation may be detrimental in treatment of cancer. Data described in this study may add to future interventions aiming at inhibition of telomerase activation during irradiation.
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Affiliation(s)
- Ron Ram
- Felsenstein Medical Research Center, Beilinson Hospital, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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23
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Poynter KR, Sachs PC, Bright AT, Breed MS, Nguyen BN, Elmore LW, Holt SE. Genetic inhibition of telomerase results in sensitization and recovery of breast tumor cells. Mol Cancer Ther 2009; 8:1319-27. [PMID: 19417141 DOI: 10.1158/1535-7163.mct-08-0849] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Telomerase, a ribonucleoprotein enzyme minimally composed of an RNA template (human telomerase RNA) and a catalytically active protein subunit (human telomerase reverse transcriptase), synthesizes telomeric repeats onto chromosome ends and is obligatory for continuous tumor cell proliferation. Telomerase is an attractive anticancer therapeutic target because its activity is present in >90% of human cancers, including >95% of breast carcinomas. Traditional chemotherapies lack the ability to effectively control and cure breast cancer, in part because residual cells are often resistant to DNA-damaging modalities. Although numerous telomerase inhibition strategies cause cancer cells to undergo apoptosis or senescence, there is often a lag period between the beginning of the treatment regimen and a biological effect. Thus, our goal for these studies was to show that effectively blocking telomerase genetically together with standard chemotherapeutic agents, doxorubicin/Adriamycin or Taxol, would increase the sensitization and efficacy for triggering senescence and/or apoptosis in cultures of breast cancer cells while reducing toxicity. We find that blocking telomerase in breast tumor cells substantially increases the sensitization at lower doses of Adriamycin or Taxol and that the kinetics of senescence/apoptosis is more rapid at higher concentrations. Combined with telomerase inhibition, Taxol treatment induced both apoptosis (its typical cell fate) and senescence, both at high enough levels to suggest that these two cellular responses are not mutually exclusive. Genetic inhibition of telomerase is eventually reversed due to up-regulation of endogenous telomerase activity without a net change in telomere length, suggesting that telomerase inhibition itself, not necessarily short telomeres, is important for sensitization.
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Affiliation(s)
- Kennon R Poynter
- Department of Human Genetics, Medical College of Virginia at Virginia Commonwealth University, Richmond, Virginia 23298-0662, USA
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24
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Ma L, Xu G, Sotnikova A, Szczepanowski M, Giefing M, Krause K, Krams M, Siebert R, Jin J, Klapper W. Loss of expression of LyGDI (ARHGDIB), a rho GDP-dissociation inhibitor, in Hodgkin lymphoma. Br J Haematol 2008; 139:217-23. [PMID: 17897297 DOI: 10.1111/j.1365-2141.2007.06782.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The guanosine triphosphatase (GTPase) inhibitor LyGDI (ARHGDIB, Ly/D4-GDI, RhoGDIb or RhoGDI 2) is abundantly expressed in haematopoetic cells and possibly plays a role in the onset of apoptosis. Gene expression profiling of Hodgkin cell lines revealed that LyGDI expression was downregulated in these cell lines. The present study evaluated the expression of LyGDI in Hodgkin cells in vivo and studied the function of LyGDI in Hodgkin cell lines in vitro. Our results showed that virtually all Hodgkin and Reed-Sternberg cells in classical Hodgkin lymphoma lacked LyGDI protein expression. On the other hand, almost all non-Hodgkin lymphomas, except for anaplastic large cell lymphomas, expressed LyGDI protein. Transfection of the classical Hodgkin cell line L428 with a vector containing full-length LyGDI-induced apoptosis in a subset of cells. However, the majority of Hodgkin cells with transgenic expression of LyGDI escaped apoptosis. Our data show that lack of LyGDI expression is a frequent feature of cHL but that it is not of vital importance for the growth and survival of these cells.
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Affiliation(s)
- Liya Ma
- Department of Pathology, Schleswig-Holstein University Hospitals, Kiel, Germany
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25
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Zhang YW, Zhang ZX, Miao ZH, Ding J. The telomeric protein TRF2 is critical for the protection of A549 cells from both telomere erosion and DNA double-strand breaks driven by salvicine. Mol Pharmacol 2007; 73:824-32. [PMID: 18025071 DOI: 10.1124/mol.107.039081] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Telomere repeat binding factor 2 (TRF2) has been increasingly recognized to be involved in DNA damage response and telomere maintenance. Our previous report found that salvicine (SAL), a novel topoisomerase II poison, elicited DNA double-strand breaks and telomere erosion in separate experimental systems. However, it remains to be clarified whether they share a common response to these two events and in particular whether TRF2 is involved in this process. In this study, we found that SAL concurrently induced DNA double-strand breaks, telomeric DNA damage, and telomere erosion in lung carcinoma A549 cells. It was unexpected to find that SAL led to disruption of TRF2, independently of either its transcription or proteasome-mediated degradation. By overexpressing the full-length trf2 gene and transfecting TRF2 small interfering RNAs, we showed that TRF2 protein protected both telomeric and genomic DNA from the SAL-elicited events. It is noteworthy that although both the Ataxia-telangiectasia-mutated (ATM) and the ATM- and Rad3-related (ATR) kinases responded to the SAL-induced DNA damages, only ATR was essential for the telomere erosion. The study also showed that the activated ATR augmented the SAL-triggered TRF2 disruption, whereas TRF2 reduction in turn enhanced ATR function. All of these findings suggest the emerging significance of TRF2 protecting both telomeric DNA and genomic DNA on the one hand and reveal the mutual modulation between ATR and TRF2 in sensing DNA damage signaling during cancer development on the other hand.
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Affiliation(s)
- Yong-Wei Zhang
- Division of Anti-Tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, People's Republic of China
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26
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Abstract
Telomeres are among the most important structures in eukaryotic cells. Creating the physical ends of linear chromosomes, they play a crucial role in maintaining genome stability, control of cell division, cell growth and senescence. In vertebrates, telomeres consist of G-rich repetitive DNA sequences (TTAGGG)n and specific proteins, creating a specialized structure called the telosome that through mutual interactions with many other factors in the cell give rise to dynamic regulation of chromosome maintenance. In this review, we survey the structural and mechanistic aspects of telomere length regulation and how these processes lead to alterations in normal and immortal cell growth.
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Affiliation(s)
- M Matulić
- Ruder Bosković Institute, Department of Molecular Biology, Zagreb, Croatia
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27
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Chen M, Gu J, Xing J, Spitz MR, Wu X. Irradiation-induced telomerase activity and the risk of lung cancer: a pilot case-control study. Cancer 2007; 109:1157-63. [PMID: 17265522 DOI: 10.1002/cncr.22493] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Telomerase activity is undetectable in most normal somatic cells, but is up-regulated by various mechanisms during tumorigenesis. Telomerase activation enables cells to overcome replicative senescence and maintain telomere stability during cell proliferation. The aim of the study was to evaluate the association between irradiation-induced telomerase activity and the risk of lung cancer. METHODS A case-control design was used that measured the baseline and gamma-radiation-induced telomerase activity in cultured peripheral blood lymphocytes from 44 lung cancer patients and 44 healthy controls. The associations between gamma-radiation-inducible telomerase activity and the risk of lung cancer were then analyzed. RESULTS The baseline telomerase activity was lower in cases than in controls (0.956 vs 1.222, P = .126). After gamma-radiation the telomerase activity in cases experienced a significant increase over baseline (1.480 vs 0.956, P < .001); the telomerase activity in controls also increased, but on a smaller scale (1.485 vs 1.222, P = .0025). The relative gamma-radiation-induced telomerase activity, defined as the ratio of the net increase of telomerase activity (gamma-radiation induced minus baseline) to the baseline telomerase activity, was significantly higher in cases than in controls (0.730 vs 0.224, P = .0003). When dichotomized, the subjects at the 75th percentile of the relative gamma-radiation-induced telomerase activity in controls, a higher ratio was associated with a significantly increased lung cancer risk (odds ratio [OR], 4.71, 95% confidence interval [CI]: 1.37, 16.21). Moreover, a dose response was observed between the relative gamma-radiation-induced telomerase activity and lung cancer risk. Compared with individuals with the lowest tertile of the relative gamma-radiation-induced telomerase activity, individuals with the second and the highest tertiles of the relative telomerase activity exhibited significantly elevated risks of lung cancer, with adjusted ORs of 12.58 (95% CI: 1.08, 146.86) and 31.08 (95% CI: 2.71, 356.81), respectively (P for trend <.001). CONCLUSIONS The pilot-case control study suggested that the gamma-radiation-induced telomerase activation is associated with a significantly increased risk of developing lung cancer. Larger case-control studies and prospective studies are needed to confirm the findings.
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Affiliation(s)
- Meng Chen
- Department of Epidemiology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA
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28
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Qian W, Liu J, Jin J, Ni W, Xu W. Arsenic trioxide induces not only apoptosis but also autophagic cell death in leukemia cell lines via up-regulation of Beclin-1. Leuk Res 2007; 31:329-39. [PMID: 16882451 DOI: 10.1016/j.leukres.2006.06.021] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Revised: 06/05/2006] [Accepted: 06/29/2006] [Indexed: 01/12/2023]
Abstract
Although recent data shows that arsenic trioxide (As2O3) is capable of inducing cell death via cell cycle arrest and apoptosis both in acute promyelocytic leukemia (APL) and in non-APL cells, the mechanisms of As2O3-mediated cell death are not fully understood. In this study, we investigated the in vitro effects of As2O3 on cell growth inhibition and cell death in human T-lymphocytic leukemia and myelodysplastic syndrome (MDS) cell lines. As2O3 significantly inhibited the proliferation of Molt-4 and Mutz-1 cells in dose- and time-dependent manner. Autophagic cell death (programmed cell death type II) and apoptosis (programmed cell death type I) were activated together in leukemia cell lines after exposed to As2O3. Numerous large cytoplasmic inclusions and vacuoles were observed in As2O3-treated cells using electron microscope. Furthermore, 3-methyladenine (an autophagy inhibitor) significantly reduced autophagic cell death and sequentially induced apoptosis. Finally, leukemia cells treated with 4 microM As2O3 showed a considerable up-regulation of Beclin-1 (a Bcl-2-interacting protein) expression, which was independent of transcription of mRNA and required protein synthesis. In addition, Molt-4 cells treated with As2O3 exhibited the down-regulation of Bax protein expression, suggesting that Bax may be involved in accumulating of Beclin-1 and triggering autophagic cell death in As2O3-treated leukemia cells. These results may lead to a better understanding of the mechanism of action of As2O3, and provide a suggestion that As2O3 may be of therapeutic value for the treatment of patients with human T-lymphocytic leukemia and myelodysplastic syndrome.
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Affiliation(s)
- Wenbin Qian
- Institute of Hematology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79# Qingchun Road, Hangzhou 310003, China.
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Lin X, Gu J, Lu C, Spitz MR, Wu X. Expression of telomere-associated genes as prognostic markers for overall survival in patients with non-small cell lung cancer. Clin Cancer Res 2006; 12:5720-5. [PMID: 17020976 DOI: 10.1158/1078-0432.ccr-05-2809] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Human telomeres, which are composed of long, repetitive sequences of TTAGGG and a variety of proteins, function as a protective structure capping the ends of chromosomes. Telomere dysfunction plays important roles in cancer initiation and progression. TRF1, TRF2, POT1, and RAP1 are four major telomere proteins that regulate telomere stability and telomere length. We hypothesized that the expression of these genes would have significant predictive value for cancer development and prognosis. EXPERIMENTAL DESIGN We compared the mRNA expression level of TRF1, TRF2, POT1, and RAP1 between tumor and adjacent normal tissues from 148 patients with non-small cell lung cancer using real-time quantitative PCR. We then estimated the prognostic value of the mRNA expression of these genes in tumors. RESULTS The expression level of TRF1 was significantly lower in tumor tissues than in adjacent normal tissues (P < 0.0001); no significant difference was found for TRF2, POT1, and RAP1. The expression of RAP1 gene in tumors was highly predictive of overall survival. In the Cox proportional hazards model, patients with higher RAP1 expression were associated with a significantly better survival [hazard ratio (HR), 0.47; 95% confidence interval (95% CI), 0.24-0.91]. This improved survival was more prominent in men (HR, 0.45; 95% CI, 0.22-0.996) and in ever smokers (HR, 0.50; 95% CI, 0.24-1.02). Kaplan-Meier survival curves showed that patients with higher RAP1 expression had significantly longer median survival than patients with lower expression (median = 51.21 versus 15.34 months, P < 0.0009). The expressions of TRF2 in tumor tissues were significantly correlated with tumor grades (P = 0.0114). CONCLUSIONS RAP1 expression may be a useful biomarker of tumor progression and survival.
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MESH Headings
- Aged
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Carcinoma, Non-Small-Cell Lung/genetics
- Carcinoma, Non-Small-Cell Lung/metabolism
- Carcinoma, Non-Small-Cell Lung/mortality
- DNA, Neoplasm/genetics
- DNA, Neoplasm/metabolism
- Female
- Gene Expression Regulation, Neoplastic
- Humans
- Lung Neoplasms/genetics
- Lung Neoplasms/mortality
- Male
- Middle Aged
- Prognosis
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Shelterin Complex
- Survival Rate
- Telomere/genetics
- Telomere/metabolism
- Telomere-Binding Proteins/genetics
- Telomere-Binding Proteins/metabolism
- Telomeric Repeat Binding Protein 1/genetics
- Telomeric Repeat Binding Protein 1/metabolism
- Telomeric Repeat Binding Protein 2/genetics
- Telomeric Repeat Binding Protein 2/metabolism
- rap1 GTP-Binding Proteins/genetics
- rap1 GTP-Binding Proteins/metabolism
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Affiliation(s)
- Xin Lin
- Departments of Epidemiology and Thoracic/Head and Neck Medical Oncology, The University of Texas M.D. Anderson Cancer Center, 1155 Pressler Boulevard, Houston, TX 77030, USA
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Chen HH, Yu CH, Wang JT, Liu BY, Wang YP, Sun A, Tsai TC, Chiang CP. Expression of human telomerase reverse transcriptase (hTERT) protein is significantly associated with the progression, recurrence and prognosis of oral squamous cell carcinoma in Taiwan. Oral Oncol 2006; 43:122-9. [PMID: 16798059 DOI: 10.1016/j.oraloncology.2006.01.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Accepted: 01/23/2006] [Indexed: 11/20/2022]
Abstract
This study used an immunohistochemical technique to examine the expression of human telomerase reverse transcriptase (hTERT) protein in 82 specimens of OSCC, 116 specimens of oral epithelial dysplasia (OED), and 21 specimens of normal oral mucosa (NOM). The cytoplasmic and nuclear hTERT staining intensity (SI; 0, no staining; 1, weak; 2, moderate; 3, strong), labeling indices (LIs, defined as the percentage of positive cells in total cells), and labeling scores (LSs, defined as LI x SI) in OSCC, OED, and NOM samples were calculated and compared among groups. The correlation between the cytoplasmic or nuclear hTERT LS in OSCCs and clinicopathological parameters or survival of OSCC patients was analyzed statistically. The mean cytoplasmic hTERT LSs increased significantly from NOM (87+/-17%) through OED (95+/-18%) to OSCC samples (114+/-33%, p=0.000). The mean nuclear hTERT LSs also increased from NOM (80+/-14%) to OED (91+/-20%) and then decreased to OSCC samples (86+/-35%) with no statistically significant difference among the 3 groups. A significant correlation was found between the higher mean cytoplasmic hTERT LSs and OSCCs occurring in male patients (p=0.023), with larger tumor sizes (T3 and T4, p=0.048), with more advanced clinical stages (stages 3 and 4, p=0.033), or from patients with areca quid chewing (p= 0.029), cigarette smoking (p=0.027), or alcohol drinking habit (p=0.025). In addition, OSCC patients with nuclear hTERT LSs greater than 100% were prone to have a higher recurrence rate (p=0.044) and a lower 5-year survival rate (p=0.011). Our results indicate that the increased expression of hTERT protein is an early event in oral carcinogenesis and hTERT may be a biomarker for OSCCs. Measuring the amount of cytoplasmic or nuclear expression of hTERT in OSCC samples may predict the oral cancer progression, recurrence, and prognosis in Taiwan.
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Affiliation(s)
- Huang-Hsu Chen
- Graduate Institute of Clinical Dentistry, College of Medicine, National Taiwan University, Taipei, Taiwan
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31
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Ning HB, Li JC, Liu ZG, Fan DM. DNA damage increases telomerase activity and mRNA expression of telomeric repeat binding factor 2 in gastric cancer cells. Shijie Huaren Xiaohua Zazhi 2006; 14:942-946. [DOI: 10.11569/wcjd.v14.i10.942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the possible involvement of telomerase and telomeric repeat binding factors (TRF1 and TRF2) in chemotherapeutic agents-induced DNA damage responses in gastric cancer cells.
METHODS: Gastric cancer cell line SGC7901 and MKN28 were treated with various concentrations of etoposide for 3, 6, 12, 24 and 36 h. Telomerase activity was measured by real-time quantitative telomeric repeat amplification protocol (RTQ-TRAP) assay. The expression of human telomerase reverse transcriptase (hTERT) mRNA was detected by real time reverse transcription polymerase chain reaction (RT-PCR). The expression of TRF1 and TRF2 were detected by Western blot and real time RT-PCR at protein and mRNA level, respectively.
RESULTS: Telomerase activity and TRF2 mRNA expression were up-regulated at the early stage of drug treatment in both cell lines (P < 0.05). The expression of TRF1 mRNA was also increased, but it was not significant (P > 0.05). The increase of telomerase activity was independent on hTERT mRNA levels, and TRF2 was significantly increased both in protein and mRNA levels (P < 0.05). The up-regulation was in a drug dose-dependent manner.
CONCLUSION: Telomerase activity and TRF2 expression is possibly involved in the responses of gastric cancer cells to DNA-damaging drugs.
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Brunori M, Mathieu N, Ricoul M, Bauwens S, Koering CE, Roborel de Climens A, Belleville A, Wang Q, Puisieux I, Décimo D, Puisieux A, Sabatier L, Gilson E. TRF2 inhibition promotes anchorage-independent growth of telomerase-positive human fibroblasts. Oncogene 2006; 25:990-7. [PMID: 16205637 DOI: 10.1038/sj.onc.1209135] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although telomere instability is observed in human tumors and is associated with the development of cancers in mice, it has yet to be established that it can contribute to the malignant transformation of human cells. We show here that in checkpoint-compromised telomerase-positive human fibroblasts an episode of TRF2 inhibition promotes heritable changes that increase the ability to grow in soft agar, but not tumor growth in nude mice. This transforming activity is associated to a burst of telomere instability but is independent of an altered control of telomere length. Moreover, it cannot be recapitulated by an increase in chromosome breaks induced by an exposure to gamma-radiations. Since it can be revealed in the context of telomerase-proficient human cells, telomere dysfunction might contribute to cancer progression even at late stages of the oncogenesis process, after the telomerase reactivation step.
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Affiliation(s)
- M Brunori
- Laboratoire de Biologie Moléculaire de la Cellule of Ecole Normale Supérieure de Lyon, UMR CNRS/INRA/ENS, Lyon, France
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Malerba I, Gribaldo L, Diodovich C, Carloni M, Meschini R, Bowe G, Collotta A. Induction of apoptosis and inhibition of telomerase activity in human bone marrow and HL-60 p53 null cells treated with anti-cancer drugs. Toxicol In Vitro 2005; 19:523-32. [PMID: 15826810 DOI: 10.1016/j.tiv.2004.12.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2004] [Revised: 12/10/2004] [Accepted: 12/17/2004] [Indexed: 10/25/2022]
Abstract
Telomerase plays a key role in the maintenance of chromosomal stability in tumours, and the ability of anti-cancer agents to inhibit telomerase activity is under investigation. In this study, we evaluated the effect of etoposide and taxol, on the telomerase activity and telomere length in human leukaemia p53 null cells and human bone marrow cells, as well as apoptosis and cell cycle modulation. Results showed that after exposure to the drugs, HL-60 cells as well as the human progenitors underwent a block in G2 and subsequently apoptosis, whereas stromal cells from bone marrow did not undergo a block in G2 or enter apoptosis after etoposide exposure. Telomere length increased in stromal cells after treatment with both etoposide and taxol whereas in HL-60 cells only after etoposide treatment with. Bax, bcl-2 and bcl-x change their expression in stromal cells, whereas bcl-x was induced after drug treatment and bcl-2 down regulated in progenitor cells. Our data suggest that telomerase activity and apoptosis are correlated and they seem to be modulated by a common gene, bcl-2.
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Affiliation(s)
- I Malerba
- Laboratory of Hematotoxicology-ECVAM, Institute for Health and Consumer Protection, Joint Research Centre-JRC, Ispra 21020 (VA), Italy
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Ward RJ, Autexier C. Pharmacological telomerase inhibition can sensitize drug-resistant and drug-sensitive cells to chemotherapeutic treatment. Mol Pharmacol 2005; 68:779-86. [PMID: 15939802 DOI: 10.1124/mol.105.011494] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Effective strategies to reverse or prevent chemotherapeutic resistance are required before cancer therapies can be curative. Telomerase is the ribonucleoprotein responsible for de novo synthesis and maintenance of telomeres, and its activity is predominantly observed in cancer cells. The telomerase enzyme has been successfully inhibited or inactivated to sensitize cells to cellular stresses; however, no studies have determined yet the effect of combining a pharmacological inhibitor of telomerase catalysis and traditional chemotherapeutics for the treatment of drug-sensitive or drug-resistant cancers. Here, we describe the effect of 2-[(E)-3-naphtalen-2-yl-but-2-enoylamino]-benzoic acid (BIBR1532), a small-molecule inhibitor of telomerase catalytic activity, on drug-resistant leukemia and breast cancer cells and their parental counterparts when treated in combination with chemotherapeutics. We observed that BIBR1532-treated cells show progressive telomere shortening, decreased proliferative capacity, and sensitization to chemotherapeutic treatment. These effects are telomere length-dependent, because cells insensitive to BIBR1532 or cells released from telomerase inhibition did not demonstrate changes in growth ability or drug sensitivity. Our novel observations suggest that pharmacological telomerase inhibition in combination therapy may be a valid strategy for the treatment of both drug-sensitive and drug-resistant cancers.
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Affiliation(s)
- Ryan J Ward
- Faculty of Medicine, Department of Anatomy and Cell Biology , McGill University, Montréal, Québec, Canada
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Nijjar T, Bassett E, Garbe J, Takenaka Y, Stampfer MR, Gilley D, Yaswen P. Accumulation and altered localization of telomere-associated protein TRF2 in immortally transformed and tumor-derived human breast cells. Oncogene 2005; 24:3369-76. [PMID: 15735711 DOI: 10.1038/sj.onc.1208482] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We have used cultured human mammary epithelial cells (HMEC) and breast tumor-derived lines to gain information on defects that occur during breast cancer progression. HMEC immortalized by a variety of agents (the chemical carcinogen benzo(a)pyrene, oncogenes c-myc and ZNF217, and/or dominant negative p53 genetic suppressor element GSE22) displayed marked upregulation (10-15 fold) of the telomere-binding protein, TRF2. Upregulation of TRF2 protein was apparently due to differences in post-transcriptional regulation, as mRNA levels remained comparable in finite lifespan and immortal HMEC. TRF2 protein was not upregulated by the oncogenic agents alone in the absence of immortalization, nor by expression of exogenously introduced hTERT genes. We found TRF2 levels to be at least twofold higher than in control cells in 11/15 breast tumor cell lines, suggesting that elevated TRF2 levels are a frequent occurrence during the transformation of breast tumor cells in vivo. The dispersed distribution of TRF2 throughout the nuclei in some immortalized and tumor-derived cells indicated that not all the TRF2 was associated with telomeres in these cells. The process responsible for accumulation of TRF2 in immortalized HMEC and breast tumor-derived cell lines may promote tumorigenesis by contributing to the cells' ability to maintain an indefinite lifespan.
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Affiliation(s)
- Tarlochan Nijjar
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Hwang MG, Kim K, Lee WK, Cho MH. AtTBP2 and AtTRP2 in Arabidopsis encode proteins that bind plant telomeric DNA and induce DNA bending in vitro. Mol Genet Genomics 2005; 273:66-75. [PMID: 15688221 DOI: 10.1007/s00438-004-1096-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Accepted: 11/16/2004] [Indexed: 10/25/2022]
Abstract
Telomeric DNA-binding proteins (TBPs) are crucial components that regulate the structure and function of eukaryotic telomeres and are evolutionarily conserved. We have identified two homologues of AtTBP1 (for Arabidopsis thaliana telomeric DNA binding protein 1), designated as AtTBP2 and AtTRP2, which encode proteins that specifically bind to the telomeric DNA of this plant. These proteins show extensive homology with other known plant TBPs. The isolated C-terminal segments of these proteins were capable of sequence-specific binding to duplex telomeric plant DNA in vitro. DNA bending assays using the Arabidopsis TBPs revealed that AtTBP1 and AtTBP2 have DNA-bending abilities comparable to that of the human homologue hTRF1, and higher than those of AtTRP1 and AtTRP2.
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Affiliation(s)
- Moo Gak Hwang
- Department of Biology, Yonsei University, Sinchon-Dong, Seodaemun-Ku, Seoul, 120-749 Republic of Korea
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37
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Tentori L, Forini O, Fossile E, Muzi A, Vergati M, Portarena I, Amici C, Gold B, Graziani G. N3-methyladenine induces early poly(ADP-ribosylation), reduction of nuclear factor-kappa B DNA binding ability, and nuclear up-regulation of telomerase activity. Mol Pharmacol 2004; 67:572-81. [PMID: 15548765 DOI: 10.1124/mol.104.004937] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Methylation of N3-adenine represents a novel pharmacological strategy for the treatment of resistant tumors. However, little is known about the biochemical pathways involved in cell death induced by N3-methyladenine. In the present study, we show that MeOSO(2) (CH(2))(2)-lexitropsin (Me-Lex), a compound generating almost exclusively N3-methyladenine (>99%), provoked a burst of poly(ADP-ribosylation) and loss of mitochondrial membrane potential in leukemia cells. These events were followed by a marked decrease in nuclear poly(ADP-ribose) polymerase-1 (PARP-1) expression and nuclear factor-kappaB (NF-kappaB) activity. Moreover, DNA damage generated by N3-methyladenine induced a marked decrease in telomerase in the cytosol that was accompanied by a transient up-regulation of activity in the nucleus, as a consequence of nuclear translocation of telomerase in response to genotoxic damage. PARP-1 inhibition blocked ADP-ribose polymer formation, preserved mitochondrial membrane integrity, and counteracted the reduction of NF-kappaB activity, thus preventing the appearance of necrosis. On the other hand, because PARP-1 is a component of the base excision repair (BER), the combination of Me-Lex + PARP-1 inhibitor triggered apoptosis as a result of disruption of BER process. In conclusion, the present study provides new insight into the cellular response to N3-adenine-selective methylating agents that can be exploited for the treatment of tumors unresponsive to classical wide-spectrum methylating agents. Moreover, the results underline the central and paradoxical role of PARP-1 in cell death induced by N3-methyladenine: effector of necrosis and coordinator of methylpurine repair.
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Affiliation(s)
- Lucio Tentori
- Department of Neuroscience, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
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Akiyama M, Yamada O, Hideshima T, Yanagisawa T, Yokoi K, Fujisawa K, Eto Y, Yamada H, Anderson KC. TNFalpha induces rapid activation and nuclear translocation of telomerase in human lymphocytes. Biochem Biophys Res Commun 2004; 316:528-32. [PMID: 15020249 DOI: 10.1016/j.bbrc.2004.02.080] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2004] [Indexed: 11/29/2022]
Abstract
Maintenance of telomeres regulates chromosomal stability and cellular mitosis through a checkpoint mechanism. Continuous cell proliferation requires telomerase to maintain chromosomal stability and to counteract the cellular mitotic clock. Importantly, nuclear expression of telomerase activity is required for elongation of telomere sequences. In this study, we show that tumor necrosis factor alpha (TNFalpha) induces telomerase activity in the cytoplasm of peripheral blood lymphocytes (PBL) at 60 min, followed by translocation of activated telomerase to the nucleus at 120 min. Conversely, the phosphoinositol 3-kinase (PI3K) inhibitor wortmannin blocks TNFalpha-induced activation of telomerase, whereas the specific NF-kappaB translocation inhibitor SN-50 blocks TNFalpha-induced nuclear translocation of activated telomerase. These studies suggest that activation and nuclear translocation of telomerase are regulated by PI3K/Akt/NF-kappaB signaling pathways in PBL.
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Affiliation(s)
- Masaharu Akiyama
- Department of Pediatrics, Jikei University School of Medicine, Tokyo 105-8461, Japan.
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