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Ali JH, Walter M. Combining old and new concepts in targeting telomerase for cancer therapy: transient, immediate, complete and combinatory attack (TICCA). Cancer Cell Int 2023; 23:197. [PMID: 37679807 PMCID: PMC10483736 DOI: 10.1186/s12935-023-03041-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 08/25/2023] [Indexed: 09/09/2023] Open
Abstract
Telomerase can overcome replicative senescence by elongation of telomeres but is also a specific element in most cancer cells. It is expressed more vastly than any other tumor marker. Telomerase as a tumor target inducing replicative immortality can be overcome by only one other mechanism: alternative lengthening of telomeres (ALT). This limits the probability to develop resistance to treatments. Moreover, telomerase inhibition offers some degree of specificity with a low risk of toxicity in normal cells. Nevertheless, only one telomerase antagonist reached late preclinical studies. The underlying causes, the pitfalls of telomerase-based therapies, and future chances based on recent technical advancements are summarized in this review. Based on new findings and approaches, we propose a concept how long-term survival in telomerase-based cancer therapies can be significantly improved: the TICCA (Transient Immediate Complete and Combinatory Attack) strategy.
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Affiliation(s)
- Jaber Haj Ali
- Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
- Institute of Clinical Chemistry and Laboratory Medicine, Universitätsmedizin Rostock, Ernst-Heydemann-Straße 6, 18057, Rostock, Germany
| | - Michael Walter
- Institute of Clinical Chemistry and Laboratory Medicine, Universitätsmedizin Rostock, Ernst-Heydemann-Straße 6, 18057, Rostock, Germany.
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2
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Li J, Glover JD, Zhang H, Peng M, Tan J, Mallick CB, Hou D, Yang Y, Wu S, Liu Y, Peng Q, Zheng SC, Crosse EI, Medvinsky A, Anderson RA, Brown H, Yuan Z, Zhou S, Xu Y, Kemp JP, Ho YYW, Loesch DZ, Wang L, Li Y, Tang S, Wu X, Walters RG, Lin K, Meng R, Lv J, Chernus JM, Neiswanger K, Feingold E, Evans DM, Medland SE, Martin NG, Weinberg SM, Marazita ML, Chen G, Chen Z, Zhou Y, Cheeseman M, Wang L, Jin L, Headon DJ, Wang S. Limb development genes underlie variation in human fingerprint patterns. Cell 2022; 185:95-112.e18. [PMID: 34995520 PMCID: PMC8740935 DOI: 10.1016/j.cell.2021.12.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 10/20/2021] [Accepted: 12/08/2021] [Indexed: 12/12/2022]
Abstract
Fingerprints are of long-standing practical and cultural interest, but little is known about the mechanisms that underlie their variation. Using genome-wide scans in Han Chinese cohorts, we identified 18 loci associated with fingerprint type across the digits, including a genetic basis for the long-recognized “pattern-block” correlations among the middle three digits. In particular, we identified a variant near EVI1 that alters regulatory activity and established a role for EVI1 in dermatoglyph patterning in mice. Dynamic EVI1 expression during human development supports its role in shaping the limbs and digits, rather than influencing skin patterning directly. Trans-ethnic meta-analysis identified 43 fingerprint-associated loci, with nearby genes being strongly enriched for general limb development pathways. We also found that fingerprint patterns were genetically correlated with hand proportions. Taken together, these findings support the key role of limb development genes in influencing the outcome of fingerprint patterning. GWAS identifies variants associated with fingerprint type across all digits Fingerprint-associated genes are strongly enriched for limb development functions Evi1 alters dermatoglyphs in mice by modulating limb rather than skin development Fingerprint patterns are genetically correlated with hand and finger proportions
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Affiliation(s)
- Jinxi Li
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai 200438, PRC; CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - James D Glover
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
| | - Haiguo Zhang
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai 200438, PRC
| | - Meifang Peng
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC; Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai 200438, PRC
| | - Jingze Tan
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai 200438, PRC
| | - Chandana Basu Mallick
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK; Centre for Genetic Disorders, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Dan Hou
- Chinese Academy of Sciences Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - Yajun Yang
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai 200438, PRC
| | - Sijie Wu
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai 200438, PRC; CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - Yu Liu
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - Qianqian Peng
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - Shijie C Zheng
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - Edie I Crosse
- Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | | | - Richard A Anderson
- MRC Centre for Reproductive Health, Queens Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Helen Brown
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
| | - Ziyu Yuan
- Fudan-Taizhou Institute of Health Sciences, Taizhou, Jiangsu 225326, PRC
| | - Shen Zhou
- Shanghai Foreign Language School, Shanghai 200083, PRC
| | - Yanqing Xu
- Forest Ridge School of the Sacred Heart, Bellevue, WA 98006, USA
| | - John P Kemp
- University of Queensland Diamantina Institute, University of Queensland, Brisbane, QLD, Australia
| | - Yvonne Y W Ho
- QIMR Berghofer Medical Rese Institute, Brisbane, QLD, Australia
| | - Danuta Z Loesch
- Psychology Department, La Trobe University, Melbourne, VIC, Australia
| | | | | | | | - Xiaoli Wu
- WeGene, Shenzhen, Guangdong 518040, PRC
| | - Robin G Walters
- Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK; Medical Research Council Population Health Research Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Kuang Lin
- Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Ruogu Meng
- Center for Data Science in Health and Medicine, Peking University, Beijing 100191, PRC
| | - Jun Lv
- Department of Epidemiology and Biostatistics, School of Public Health, Peking University Health Science Center, Beijing 100191, PRC
| | - Jonathan M Chernus
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Katherine Neiswanger
- Center for Craniofacial and Dental Genetics, Department of Oral and Craniofacial Sciences, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Eleanor Feingold
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - David M Evans
- University of Queensland Diamantina Institute, University of Queensland, Brisbane, QLD, Australia; Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD, Australia; MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
| | - Sarah E Medland
- QIMR Berghofer Medical Rese Institute, Brisbane, QLD, Australia
| | | | - Seth M Weinberg
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA 15261, USA; Center for Craniofacial and Dental Genetics, Department of Oral and Craniofacial Sciences, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Anthropology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Mary L Marazita
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA 15261, USA; Center for Craniofacial and Dental Genetics, Department of Oral and Craniofacial Sciences, University of Pittsburgh, Pittsburgh, PA 15219, USA; Clinical and Translational Science, University of Pittsburgh, Pittsburgh, PA 15261, USA; Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Gang Chen
- WeGene, Shenzhen, Guangdong 518040, PRC
| | - Zhengming Chen
- Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK; Medical Research Council Population Health Research Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Yong Zhou
- Clinical Research Institute, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PRC
| | - Michael Cheeseman
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
| | - Lan Wang
- Chinese Academy of Sciences Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - Li Jin
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai 200438, PRC; CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC; Research Unit of Dissecting the Population Genetics and Developing New Technologies for Treatment and Prevention of Skin Phenotypes and Dermatological Diseases (2019RU058), Chinese Academy of Medical Sciences, Shanghai 200438, PRC.
| | - Denis J Headon
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK.
| | - Sijia Wang
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC; Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, PRC.
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Raghunandan M, Geelen D, Majerova E, Decottignies A. NHP2 downregulation counteracts hTR-mediated activation of the DNA damage response at ALT telomeres. EMBO J 2021; 40:e106336. [PMID: 33595114 DOI: 10.15252/embj.2020106336] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 01/15/2021] [Accepted: 01/18/2021] [Indexed: 11/09/2022] Open
Abstract
About 10% of cancer cells employ the "alternative lengthening of telomeres" (ALT) pathway instead of re-activating the hTERT subunit of human telomerase. The hTR RNA subunit is also abnormally silenced in some ALT+ cells not expressing hTERT, suggesting a possible negative non-canonical impact of hTR on ALT. Indeed, we show that ectopically expressed hTR reduces phosphorylation of ssDNA-binding protein RPA (p-RPAS33 ) at ALT telomeres by promoting the hnRNPA1- and DNA-PK-dependent depletion of RPA. The resulting defective ATR checkpoint signaling at telomeres impairs recruitment of the homologous recombination protein, RAD51. This induces ALT telomere fragility, increases POLD3-dependent C-circle production, and promotes the recruitment of the DNA damage marker 53BP1. In ALT+ cells that naturally retain hTR expression, NHP2 H/ACA ribonucleoprotein levels are downregulated, likely in order to restrain DNA damage response (DDR) activation at telomeres through reduced 53BP1 recruitment. This unexpected role of NHP2 is independent from hTR's non-canonical function in modulating telomeric p-RPAS33 . Collectively, our study shines new light on the interference between telomerase- and ALT-dependent pathways and unravels a crucial role for hTR and NHP2 in DDR regulation at ALT telomeres.
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Affiliation(s)
- Maya Raghunandan
- Genetic and Epigenetic Alterations of Genomes, de Duve Institute, Faculty of Pharmacy and Biomedical Sciences, Université catholique de Louvain, Brussels, Belgium
| | - Dan Geelen
- Genetic and Epigenetic Alterations of Genomes, de Duve Institute, Faculty of Pharmacy and Biomedical Sciences, Université catholique de Louvain, Brussels, Belgium
| | - Eva Majerova
- Genetic and Epigenetic Alterations of Genomes, de Duve Institute, Faculty of Pharmacy and Biomedical Sciences, Université catholique de Louvain, Brussels, Belgium
| | - Anabelle Decottignies
- Genetic and Epigenetic Alterations of Genomes, de Duve Institute, Faculty of Pharmacy and Biomedical Sciences, Université catholique de Louvain, Brussels, Belgium
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Gala K, Khattar E. Long non-coding RNAs at work on telomeres: Functions and implications in cancer therapy. Cancer Lett 2021; 502:120-132. [PMID: 33450357 DOI: 10.1016/j.canlet.2020.12.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 12/13/2020] [Accepted: 12/29/2020] [Indexed: 12/27/2022]
Abstract
Long non-coding RNAs (lncRNAs) are known to regulate various biological processes including cancer. Cancer cells possess limitless replicative potential which is attained by telomere length maintenance while normal somatic cells have a limited lifespan because their telomeres shorten with every cell division ultimately triggering replicative senescence. Two lncRNAs have been observed to play a key role in telomere length maintenance. First is the lncRNA TERC (telomerase RNA component) which functions as a template for telomeric DNA synthesis in association with telomerase reverse transcriptase (TERT) which serves as the catalytic component. Together they constitute the telomerase complex which functions as a reverse transcriptase to elongate telomeres. Second lncRNA that helps in regulating telomere length is the telomeric repeat-containing RNA (TERRA) which is transcribed from the subtelomeric region and extends to the telomeric region. TERC and TERRA exhibit important functions in cancer with implications in precision oncology. In this review, we discuss various aspects of these important lncRNAs in humans and their role in cancer along with recent advancements in their anticancer therapeutic application.
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Affiliation(s)
- Kavita Gala
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, 400056, Maharashtra, India
| | - Ekta Khattar
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, 400056, Maharashtra, India.
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5
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Borbora D, Dutta HK, Devi KR, Mahanta J, Medhi P, Narain K. Long telomeres cooperate with p53, MDM2, and p21 polymorphisms to raise pediatric solid tumor risk. Pediatr Int 2019; 61:759-767. [PMID: 31211452 DOI: 10.1111/ped.13915] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 06/05/2019] [Accepted: 06/14/2019] [Indexed: 12/20/2022]
Abstract
BACKGROUND While leukocyte telomere length has been linked with altered risk in adult cancer, limited information is available on its association with risk in pediatric solid tumors. We investigated the association of telomeric alterations with risk of pediatric solid tumors. We also investigated whether altered telomeres cooperated with the TP53 rs1042522, MDM2 rs2279744 and CDKN1A (p21cip1 ) rs1059234 single-nucleotide polymorphisms to modify cancer risk. METHODS A total of 101 tumor patients and 202 controls were recruited for this age- and gender-matched case-control study. Relative telomere length (RTL) was determined in peripheral blood leukocytes using quantitative real-time polymerase chain reaction (PCR), and the polymorphisms were genotyped using PCR-restriction fragment length polymorphism. RESULTS Using median RTL in the healthy controls as a cut-off, children with longer telomeres were at an increased risk of developing a solid tumor (OR, 2.70; P < 0.01). When participants were categorized according to control RTL quartiles, a significant dose-response relationship was observed (χ2 = 10.95; P < 0.001). The risk for tumors increased nearly threefold (P = 0.001) for the triple interaction RTL × TP53 rs1042522 × p21cip1 rs1059234 compared with the maximum effect of any single factor, although the interaction effect was less than additive. The MDM2 rs2279744 GG genotype reduced pediatric solid tumor risk significantly (OR, 0.51). CONCLUSION Combined analysis of telomeres and genetic polymorphisms in the TP53 pathway can provide important clues to understanding pediatric solid tumor etiology.
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Affiliation(s)
- Debasish Borbora
- Regional Medical Research Centre, NE Region (ICMR), Dibrugarh, Assam, India.,Centre for Biotechnology and Bioinformatics, Dibrugarh University, Dibrugarh, Assam, India.,Department of Biotechnology, Gauhati University, Guwahati, Assam, India
| | - Hemonta K Dutta
- Department of Pediatric surgery, Assam Medical College and Hospital, Dibrugarh, Assam, India
| | - Kangjam Rekha Devi
- Regional Medical Research Centre, NE Region (ICMR), Dibrugarh, Assam, India
| | - Jagadish Mahanta
- Regional Medical Research Centre, NE Region (ICMR), Dibrugarh, Assam, India
| | - Pronita Medhi
- Department of Pathology, Assam Medical College and Hospital, Dibrugarh, Assam, India
| | - Kanwar Narain
- Regional Medical Research Centre, NE Region (ICMR), Dibrugarh, Assam, India
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Telomerase Activity is Downregulated Early During Human Brain Development. Genes (Basel) 2016; 7:genes7060027. [PMID: 27322326 PMCID: PMC4929426 DOI: 10.3390/genes7060027] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 05/25/2016] [Accepted: 06/06/2016] [Indexed: 12/14/2022] Open
Abstract
Changes in hTERT splice variant expression have been proposed to facilitate the decrease of telomerase activity during fetal development in various human tissues. Here, we analyzed the expression of telomerase RNA (hTR), wild type and α-spliced hTERT in developing human fetal brain (post conception weeks, pcw, 6-19) and in young and old cortices using qPCR and correlated it to telomerase activity measured by TRAP assay. Decrease of telomerase activity occurred early during brain development and correlated strongest to decreased hTR expression. The expression of α-spliced hTERT increased between pcw 10 and 19, while that of wild type hTERT remained unchanged. Lack of expression differences between young and old cortices suggests that most changes seem to occur early during human brain development. Using in vitro differentiation of neural precursor stem cells (NPSCs) derived at pcw 6 we found a decrease in telomerase activity but no major expression changes in telomerase associated genes. Thus, they do not seem to model the mechanisms for the decrease in telomerase activity in fetal brains. Our results suggest that decreased hTR levels, as well as transient increase in α-spliced hTERT, might both contribute to downregulation of telomerase activity during early human brain development between 6 and 17 pcw.
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Yaswen P, MacKenzie KL, Keith WN, Hentosh P, Rodier F, Zhu J, Firestone GL, Matheu A, Carnero A, Bilsland A, Sundin T, Honoki K, Fujii H, Georgakilas AG, Amedei A, Amin A, Helferich B, Boosani CS, Guha G, Ciriolo MR, Chen S, Mohammed SI, Azmi AS, Bhakta D, Halicka D, Niccolai E, Aquilano K, Ashraf SS, Nowsheen S, Yang X. Therapeutic targeting of replicative immortality. Semin Cancer Biol 2015; 35 Suppl:S104-S128. [PMID: 25869441 PMCID: PMC4600408 DOI: 10.1016/j.semcancer.2015.03.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 03/06/2015] [Accepted: 03/13/2015] [Indexed: 12/15/2022]
Abstract
One of the hallmarks of malignant cell populations is the ability to undergo continuous proliferation. This property allows clonal lineages to acquire sequential aberrations that can fuel increasingly autonomous growth, invasiveness, and therapeutic resistance. Innate cellular mechanisms have evolved to regulate replicative potential as a hedge against malignant progression. When activated in the absence of normal terminal differentiation cues, these mechanisms can result in a state of persistent cytostasis. This state, termed “senescence,” can be triggered by intrinsic cellular processes such as telomere dysfunction and oncogene expression, and by exogenous factors such as DNA damaging agents or oxidative environments. Despite differences in upstream signaling, senescence often involves convergent interdependent activation of tumor suppressors p53 and p16/pRB, but can be induced, albeit with reduced sensitivity, when these suppressors are compromised. Doses of conventional genotoxic drugs required to achieve cancer cell senescence are often much lower than doses required to achieve outright cell death. Additional therapies, such as those targeting cyclin dependent kinases or components of the PI3K signaling pathway, may induce senescence specifically in cancer cells by circumventing defects in tumor suppressor pathways or exploiting cancer cells’ heightened requirements for telomerase. Such treatments sufficient to induce cancer cell senescence could provide increased patient survival with fewer and less severe side effects than conventional cytotoxic regimens. This positive aspect is countered by important caveats regarding senescence reversibility, genomic instability, and paracrine effects that may increase heterogeneity and adaptive resistance of surviving cancer cells. Nevertheless, agents that effectively disrupt replicative immortality will likely be valuable components of new combinatorial approaches to cancer therapy.
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Affiliation(s)
- Paul Yaswen
- Life Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, United States.
| | - Karen L MacKenzie
- Children's Cancer Institute Australia, Kensington, New South Wales, Australia.
| | | | | | | | - Jiyue Zhu
- Washington State University College of Pharmacy, Pullman, WA, United States.
| | | | | | - Amancio Carnero
- Instituto de Biomedicina de Sevilla, HUVR, Consejo Superior de Investigaciones Cientificas, Universdad de Sevilla, Seville, Spain.
| | | | | | | | | | | | | | - Amr Amin
- United Arab Emirates University, Al Ain, United Arab Emirates; Cairo University, Cairo, Egypt
| | - Bill Helferich
- University of Illinois at Urbana Champaign, Champaign, IL, United States
| | | | - Gunjan Guha
- SASTRA University, Thanjavur, Tamil Nadu, India
| | | | - Sophie Chen
- Ovarian and Prostate Cancer Research Trust, Guildford, Surrey, United Kingdom
| | | | - Asfar S Azmi
- Karmanos Cancer Institute, Wayne State University, Detroit, MI, United States
| | | | | | | | | | - S Salman Ashraf
- United Arab Emirates University, Al Ain, United Arab Emirates; Cairo University, Cairo, Egypt
| | | | - Xujuan Yang
- University of Illinois at Urbana Champaign, Champaign, IL, United States
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Mathematical model of a telomerase transcriptional regulatory network developed by cell-based screening: analysis of inhibitor effects and telomerase expression mechanisms. PLoS Comput Biol 2014; 10:e1003448. [PMID: 24550717 PMCID: PMC3923661 DOI: 10.1371/journal.pcbi.1003448] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 11/30/2013] [Indexed: 12/16/2022] Open
Abstract
Cancer cells depend on transcription of telomerase reverse transcriptase (TERT). Many transcription factors affect TERT, though regulation occurs in context of a broader network. Network effects on telomerase regulation have not been investigated, though deeper understanding of TERT transcription requires a systems view. However, control over individual interactions in complex networks is not easily achievable. Mathematical modelling provides an attractive approach for analysis of complex systems and some models may prove useful in systems pharmacology approaches to drug discovery. In this report, we used transfection screening to test interactions among 14 TERT regulatory transcription factors and their respective promoters in ovarian cancer cells. The results were used to generate a network model of TERT transcription and to implement a dynamic Boolean model whose steady states were analysed. Modelled effects of signal transduction inhibitors successfully predicted TERT repression by Src-family inhibitor SU6656 and lack of repression by ERK inhibitor FR180204, results confirmed by RT-QPCR analysis of endogenous TERT expression in treated cells. Modelled effects of GSK3 inhibitor 6-bromoindirubin-3′-oxime (BIO) predicted unstable TERT repression dependent on noise and expression of JUN, corresponding with observations from a previous study. MYC expression is critical in TERT activation in the model, consistent with its well known function in endogenous TERT regulation. Loss of MYC caused complete TERT suppression in our model, substantially rescued only by co-suppression of AR. Interestingly expression was easily rescued under modelled Ets-factor gain of function, as occurs in TERT promoter mutation. RNAi targeting AR, JUN, MXD1, SP3, or TP53, showed that AR suppression does rescue endogenous TERT expression following MYC knockdown in these cells and SP3 or TP53 siRNA also cause partial recovery. The model therefore successfully predicted several aspects of TERT regulation including previously unknown mechanisms. An extrapolation suggests that a dominant stimulatory system may programme TERT for transcriptional stability. Tumour cells acquire the ability to divide and multiply indefinitely whereas normal cells can undergo only a limited number of divisions. The switch to immortalisation of the tumour cell is dependent on maintaining the integrity of telomere DNA which forms chromosome ends and is achieved through activation of the telomerase enzyme by turning on synthesis of the TERT gene, which is usually silenced in normal cells. Suppressing telomerase is toxic to cancer cells and it is widely believed that understanding TERT regulation could lead to potential cancer therapies. Previous studies have identified many of the factors which individually contribute to activate or repress TERT levels in cancer cells. However, transcription factors do not behave in isolation in cells, but rather as a complex co-operative network displaying inter-regulation. Therefore, full understanding of TERT regulation will require a broader view of the transcriptional network. In this paper we take a computational modelling approach to study TERT regulation at the network level. We tested interactions between 14 TERT-regulatory factors in an ovarian cancer cell line using a screening approach and developed a model to analyse which network interventions were able to silence TERT.
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Deb SP, Singh S, Deb S. MDM2 overexpression, activation of signaling networks, and cell proliferation. Subcell Biochem 2014; 85:215-34. [PMID: 25201197 DOI: 10.1007/978-94-017-9211-0_12] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Frequent overexpression of MDM2 in human cancers suggests that the protein confers a survival advantage to cancer cells. However, overexpression of MDM2 in normal cells seems to restrict cell proliferation. This review discusses the cell growth regulatory functions of MDM2 in normal and genetically defective cells to assess how cancer cells evade the growth-restricting consequence of MDM2 overexpression. Similar to oncoproteins that induce a DNA damage response and oncogene induced senescence in non-transformed cells, MDM2 induces G1-arrest and intra-S phase checkpoint responses that control untimely DNA replication in the face of genetic challenges.
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Affiliation(s)
- Swati Palit Deb
- Department of Biochemistry and Molecular Biology, and the Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, 23298, USA,
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10
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Hitzenbichler F, Stoehr CG, Rogenhofer M, Wieland WF, Ruemmele P, Hartmann A, Stoehr R. Mdm2 SNP309 G-variant is associated with invasive growth of human urinary bladder cancer. Pathobiology 2013; 81:53-9. [PMID: 24217660 DOI: 10.1159/000355976] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 09/24/2013] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Human mouse double minute 2 (Mdm2) is essential in degrading p53 by acting as an ubiquitin ligase and therefore plays a vital role in cell cycle and survival. The G-variant of the Mdm2 SNP309, which is located within the promoter of the Mdm2 gene, increases expression of Mdm2 and thereby inhibits the p53 pathway. Several studies have investigated the influence of this SNP on disease risk and onset of various malignancies. The impact of Mdm2 SNP309 on bladder cancer is still to be established due to inconsistent data. METHODS In a case-control study we determined the distribution of Mdm2 SNP309 genotypes in 111 patients with an early-onset bladder cancer (diagnosis <45 years of age), in 113 consecutive bladder cancer patients and in a control group consisting of 140 patients without any malignancy. RESULTS There was no significant association between the allelic distribution of the Mdm2 SNP309 and tumor risk, early onset, gender or grade of the tumor. According to tumor stage we found a significant difference in the distribution of the Mdm2 SNP309 between patients with noninvasive and invasive (≥pT1) tumor growth (p = 0.016). In patients with invasive tumors a significant increase of the G allele was found (T/T vs. T/G + G/G; p = 0.023; OR 2.203, 95% CI 1.111-4.369). CONCLUSION These data indicate that the G-variant of the Mdm2 SNP309 might influence the development of a more aggressive tumor phenotype in patients with bladder cancer without affecting the overall tumor risk.
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Affiliation(s)
- Florian Hitzenbichler
- Department of Internal Medicine I, Caritas St. Josef Medical Center, University of Regensburg, Regensburg, Germany
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11
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Photocatalysis-assisted water filtration: using TiO2-coated vertically aligned multi-walled carbon nanotube array for removal of Escherichia coli O157:H7. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2013; 33:4392-400. [PMID: 23910358 DOI: 10.1016/j.msec.2013.06.039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 06/20/2013] [Accepted: 06/23/2013] [Indexed: 11/21/2022]
Abstract
A porous ceramic was coated with vertically aligned multi-walled carbon nanotubes (MWCNTs) by spray pyrolysis. Titanium dioxide (TiO2) nanoparticles were then coated onto this densely aligned MWCNT. The presence of TiO2/MWCNT interfacial arrays was confirmed by X-ray diffraction (XRD), scanning electron microscope-energy dispersive analysis of X-ray (SEM-EDAX) and transmission electron microscope (TEM). This is a novel report in which water loaded with a most dreadful enterohemorrhagic pathogenic strain of Escherichia coli O157:H7 was filtered through TiO2/MWCNT coated porous ceramic filter and then analysed. Bacterial removal performance was found to be significantly lower in control i.e. plain porous ceramic (P<0.05) as compared to TiO2/MWCNT coated ceramic. The photocatalytic killing rate constant for TiO2-ceramic and MWCNT/TiO2-ceramic under fluorescent light was found be 1.45×10(-2) min(-1) and 2.23×10(-2) min(-1) respectively. Further, when I-V characteristics were performed for TiO2/MWCNT composite, it was corroborated that the current under light irradiation is comparatively higher than that in dark, thus proving it to be photocatalytically efficient system. The enhanced photocatalysis may be a contribution of increased surface area and charge transfer rate as a consequence of aligned MWCNT network.
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12
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Hwang TH, Atluri G, Kuang R, Kumar V, Starr T, Silverstein KAT, Haverty PM, Zhang Z, Liu J. Large-scale integrative network-based analysis identifies common pathways disrupted by copy number alterations across cancers. BMC Genomics 2013; 14:440. [PMID: 23822816 PMCID: PMC3703268 DOI: 10.1186/1471-2164-14-440] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 06/26/2013] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Many large-scale studies analyzed high-throughput genomic data to identify altered pathways essential to the development and progression of specific types of cancer. However, no previous study has been extended to provide a comprehensive analysis of pathways disrupted by copy number alterations across different human cancers. Towards this goal, we propose a network-based method to integrate copy number alteration data with human protein-protein interaction networks and pathway databases to identify pathways that are commonly disrupted in many different types of cancer. RESULTS We applied our approach to a data set of 2,172 cancer patients across 16 different types of cancers, and discovered a set of commonly disrupted pathways, which are likely essential for tumor formation in majority of the cancers. We also identified pathways that are only disrupted in specific cancer types, providing molecular markers for different human cancers. Analysis with independent microarray gene expression datasets confirms that the commonly disrupted pathways can be used to identify patient subgroups with significantly different survival outcomes. We also provide a network view of disrupted pathways to explain how copy number alterations affect pathways that regulate cell growth, cycle, and differentiation for tumorigenesis. CONCLUSIONS In this work, we demonstrated that the network-based integrative analysis can help to identify pathways disrupted by copy number alterations across 16 types of human cancers, which are not readily identifiable by conventional overrepresentation-based and other pathway-based methods. All the results and source code are available at http://compbio.cs.umn.edu/NetPathID/.
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Affiliation(s)
- Tae Hyun Hwang
- Masonic Cancer Center, University of Minnesota – Twin Cities, Minneapolis, MN, USA
- Quantitative Biomedical Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Clinical Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Gowtham Atluri
- Department of Computer Science and Engineering, University of Minnesota – Twin Cities, Minneapolis, MN, USA
| | - Rui Kuang
- Department of Computer Science and Engineering, University of Minnesota – Twin Cities, Minneapolis, MN, USA
| | - Vipin Kumar
- Department of Computer Science and Engineering, University of Minnesota – Twin Cities, Minneapolis, MN, USA
| | - Timothy Starr
- Masonic Cancer Center, University of Minnesota – Twin Cities, Minneapolis, MN, USA
- Department of Obstetrics, Gynecology & Women’s Health, University of Minnesota, Minneapolis, MN, USA
| | - Kevin AT Silverstein
- Masonic Cancer Center, University of Minnesota – Twin Cities, Minneapolis, MN, USA
| | - Peter M Haverty
- Department of Bioinformatics and Computational Biology, Genentech Inc, South San Francisco, CA, USA
| | - Zemin Zhang
- Department of Bioinformatics and Computational Biology, Genentech Inc, South San Francisco, CA, USA
| | - Jinfeng Liu
- Department of Bioinformatics and Computational Biology, Genentech Inc, South San Francisco, CA, USA
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13
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Vaughan C, Mohanraj L, Singh S, Dumur CI, Ramamoorthy M, Garrett CT, Windle B, Yeudall WA, Deb S, Deb SP. Human Oncoprotein MDM2 Up-regulates Expression of NF-κB2 Precursor p100 Conferring a Survival Advantage to Lung Cells. Genes Cancer 2012; 2:943-55. [PMID: 22701761 DOI: 10.1177/1947601911436008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 12/24/2011] [Indexed: 12/12/2022] Open
Abstract
The current model predicts that MDM2 is primarily overexpressed in cancers with wild-type (WT) p53 and contributes to oncogenesis by degrading p53. Following a correlated expression of MDM2 and NF-κB2 transcripts in human lung tumors, we have identified a novel transactivation function of MDM2. Here, we report that in human lung tumors, overexpression of MDM2 was found in approximately 30% of cases irrespective of their p53 status, and expression of MDM2 and NF-κB2 transcripts showed a highly significant statistical correlation in tumors with WT p53. We investigated the significance of this correlated expression in terms of mechanism and biological function. Increase in MDM2 expression from its own promoter in transgenic mice remarkably enhanced expression of NF-κB2 compared with its non-transgenic littermates. Knockdown or elimination of endogenous MDM2 expression in cultured non-transformed or lung tumor cells drastically reduced expression of NF-κB2 transcripts, suggesting a normal physiological role of MDM2 in regulating NF-κB2 transcription. MDM2 could up-regulate expression of NF-κB2 transcripts when its p53-interaction domain was blocked with Nutlin-3, indicating that the MDM2-p53 interaction is dispensable for up-regulation of NF-κB2 expression. Consistently, analysis of functional domains of MDM2 indicated that although the p53-interaction domain of MDM2 contributes to the up-regulation of the NFκB2 promoter, MDM2 does not require direct interactions with p53 for this function. Accordingly, MDM2 overexpression in non-transformed or lung cancer cells devoid of p53 also generated a significant increase in the expression of NF-κB2 transcript and its targets CXCL-1 and CXCL-10, whereas elimination of MDM2 expression had the opposite effects. MDM2-mediated increase in p100/NF-κB2 expression reduced cell death mediated by paclitaxel. Furthermore, knockdown of NF-κB2 expression retarded cell proliferation. Based on these data, we propose that MDM2-mediated NF-κB2 up-regulation is a combined effect of p53-dependent and independent mechanisms and that it confers a survival advantage to lung cancer cells.
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Affiliation(s)
- Catherine Vaughan
- Department of Biochemistry & Molecular Biology, Virginia Commonwealth University, Richmond, VA, USA
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14
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Mezzasoma L, Antognelli C, Del Buono C, Stracci F, Cottini E, Cochetti G, Talesa VN, Mearini E. Expression and biological-clinical significance of hTR, hTERT and CKS2 in washing fluids of patients with bladder cancer. BMC Urol 2010; 10:17. [PMID: 20920335 PMCID: PMC2959011 DOI: 10.1186/1471-2490-10-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 10/04/2010] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND at present, pathogenesis of bladder cancer (BC) has not been fully elucidated. Aim of this study is to investigate the role of human telomerase RNA (hTR), human telomerase reverse transcriptase (hTERT) and CDC28 protein kinase regulatory subunit 2 (CKS2) in bladder carcinogenesis and their possible clinical significance; METHODS the transcript levels of hTR, hTERT and CKS2 were quantified by Real time reverse transcriptase chain reaction in exfoliated cells from bladder washings of 36 patients with BC and 58 controls. The statistical significance of differences between BC bearing patients and control groups, in the general as well as in the stratified analysis (superficial or invasive BC), was assessed by Student's t test. Non parametric Receiver Operating Characteristics analysis (ROC) was performed to ascertain the accuracy of study variables to discriminate between BC and controls. The clinical value of concomitant examination of hTR, hTERT and CKS2 was evaluated by logistic regression analysis; RESULTS a significant decrease in hTR and a significant increase in hTERT or CKS2 gene expression were found between BC bearing patients and controls, as well as in the subgroups analysis. The area under the curve (AUC) indicated an average discrimination power for the three genes, both in the general and subgroups analysis, when singularly considered. The ability to significantly discriminate between superficial and invasive BC was observed only for hTR transcript levels. A combined model including hTR and CKS2 was the best one in BC diagnosis; CONCLUSIONS our results, obtained from a sample set particularly rich of exfoliated cells, provide further molecular evidence on the involvement of hTR, hTERT and CKS2 gene expression in BC carcinogenesis. In particular, while hTERT and CKS2 gene expression seems to have a major involvement in the early stages of the disease, hTR gene expression, seems to be more involved in progression. In addition, our findings suggest that the studied genes have a clinical role in discriminating between BC and controls in the general as well as in the stratified analysis, when singularly considered. A combined model improved over the single marker BC diagnosis.
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Affiliation(s)
- Letizia Mezzasoma
- Department of Experimental Medicine, Division of Cell and Molecular Biology, University of Perugia, and Didactic and Scientific District of Terni, Santa Maria General Hospital, Via Del Giochetto 06122 Perugia, Italy.
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15
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Skvortzov DA, Rubzova MP, Zvereva ME, Kiselev FL, Donzova OA. The regulation of telomerase in oncogenesis. Acta Naturae 2009; 1:51-67. [PMID: 22649586 PMCID: PMC3347505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The influence that the expression of the human (glial-derived neurotrophic factor (GDNF)) neurotrophic factor has on the morphology and proliferative activity of embryonic stem cells (SC) of a mouse with R1 lineage, as well as their ability to form embroid bodies (EB), has been studied. Before that, using a PCR (polymerase chain reaction) coupled with reverse transcription, it was shown that, in this very lineage of the embryonic SC, the expression of the receptors' genes is being fulfilled for the neurotropfic RET and GFRα1 glia factor. The mouse's embryonic SC lineage has been obtained, transfected by the human GDNF gene, and has been fused with the "green" fluorescent protein (GFP) gene. The presence of the expression of the human GDNF gene in the cells was shown by northern hybridization and the synthesis of its albuminous product by immunocitochemical coloration with the use of specific antibodies. The reliable slowing-down of the embriod-body formation by the embryonic SC transfected by the GDNF gene has been shown. No significant influence of the expression of the GDNF gene on the morphology and the proliferative activity of the transfected embryonic SCs has been found when compared with the control ones.
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Affiliation(s)
- D A Skvortzov
- Department of Chemistry, Moscow State University, 119992 Moscow
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16
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Cairney CJ, Hoare SF, Daidone MG, Zaffaroni N, Keith WN. High level of telomerase RNA gene expression is associated with chromatin modification, the ALT phenotype and poor prognosis in liposarcoma. Br J Cancer 2008; 98:1467-74. [PMID: 18414473 PMCID: PMC2361713 DOI: 10.1038/sj.bjc.6604328] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Telomere length is maintained by two known mechanisms, activation of telomerase or alternative lengthening of telomeres (ALT). The ALT pathway is more commonly activated in tumours of mesenchymal origin, although the mechanisms involved in the decision of a cell to activate either telomerase or ALT are unknown at present and no molecular markers exist to define the ALT phenotype. We have previously shown an association between chromatin remodelling, telomerase gene expression and ALT in cell line models. Here, we evaluate these findings and investigate their prognostic significance in a panel of liposarcoma tissue samples to understand the biology underlying the ALT phenotype. Liposarcoma samples were split into three groups: telomerase positive (Tel+); ALT positive; ALT−/Tel−. Differences in telomerase gene expression were evident between the groups with increased expression of hTR in ALT and Tel+ compared to ALT−/Tel− samples and increased hTERT in Tel+ samples only. Investigation of a small panel of chromatin modifications revealed significantly increased binding of acetyl H3 in association with hTR expression. We confirm that the presence of the ALT phenotype is associated with poor prognosis and in addition, for the first time, we show a direct association between hTR expression and poor prognosis in liposarcoma patients.
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Affiliation(s)
- C J Cairney
- Centre for Oncology and Applied Pharmacology, University of Glasgow, Cancer Research UK Beatson Laboratories, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
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17
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Telomere stability and telomerase in mesenchymal stem cells. Biochimie 2008; 90:33-40. [DOI: 10.1016/j.biochi.2007.09.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Accepted: 09/10/2007] [Indexed: 01/25/2023]
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Cairney CJ, Keith WN. Telomerase redefined: Integrated regulation of hTR and hTERT for telomere maintenance and telomerase activity. Biochimie 2008; 90:13-23. [PMID: 17854971 DOI: 10.1016/j.biochi.2007.07.025] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Accepted: 07/23/2007] [Indexed: 10/23/2022]
Abstract
Telomerase activity is dependent on the expression of 2 main core component genes, hTERT, which encodes the catalytic component and hTR (also called TERC), which encodes the RNA component. The correlation between telomerase activity and carcinogenesis has made this molecule of great interest in cancer research, however in order to fully understand the regulation of telomerase the mechanisms controlling both telomerase genes need to be studied. Some of these mechanisms of regulation have begun to emerge, however many more remain to be deciphered. For many years hTERT has been regarded as the limiting component of telomerase and much of the research in this field has focussed on its regulation, however it was clear from an early stage that hTR expression was also tightly regulated in normal cells and disease. More recently evidence from biochemistry, promoter studies and mouse models has been steadily increasing for a role for hTR as a limiting and essential component for telomerase activity and telomere maintenance. Perhaps the time has come to redefine our view of telomerase regulation. Knowledge of the mechanisms controlling both telomerase genes in normal systems and cancer may aid our understanding of the role of telomerase in carcinogenesis or highlight potential areas for therapeutic intervention. Here we review the essential requirement of hTR for telomere maintenance and telomerase activity in normal tissues and disease and focus on recent advances in our understanding of hTR regulation in relation to hTERT.
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Affiliation(s)
- C J Cairney
- Centre for Oncology and Applied Pharmacology, University of Glasgow, Cancer Research UK Beatson Laboratories, Bearsden, Glasgow G61 1BD, UK
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Frum R, Busby SA, Ramamoorthy M, Deb S, Shabanowitz J, Hunt DF, Deb SP. HDM2-binding partners: interaction with translation elongation factor EF1alpha. J Proteome Res 2007; 6:1410-7. [PMID: 17373842 PMCID: PMC4626875 DOI: 10.1021/pr060584p] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To understand the cellular functions of HDM2, we attempted to identify novel HDM2-interacting proteins by proteomic analysis. Along with previously identified interactions with the ribosomal proteins, our analysis reveals interactions of HDM2 with the ribosomal translation elongation factor EF1alpha, 40S ribosomal protein S20, tubulins, glyceraldehyde 3-phosphate dehydrogenase, and a proteolysis-inducing factor dermicidin in the absence of tumor suppressor p53. Because a CTCL tumor antigen HD-CL-08 has high degree of homology with EF1alpha, we confirmed interaction of HDM2 with EF1alpha by immunoprecipitation and Western blot analysis in transformed as well as near normal diploid cells. Endogenous HDM2- EF1alpha complex was detected in cancer cells overexpressing HDM2, suggesting a possible role of this interaction in HDM2-mediated oncogenesis. Consistent with their interaction, colocalization of HDM2 and EF1alpha can be detected in the cytoplasm of normal or transformed cells. Amino acid residues 1-58 and 221-325 of HDM2 were found to be essential for its interaction with EF1alpha, suggesting that the interaction is independent of its other ribosomal interacting proteins L5, L11, and L23. Overexpression of HDM2 did not affect translation. Because EF1alpha has been implicated in DNA replication and severing of microtubules, interaction of HDM2 with EF1alpha may signify a p53-independent cell growth regulatory role of HDM2.
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Affiliation(s)
| | | | | | | | | | | | - Swati P. Deb
- To whom correspondence should be addessed. Address: Goodwin Research Laboratory, P.O. Box 980035, 401 College Street, Virginia Commonwealth University, Richmond, VA 23298. Phone: 804-828-9541. Fax: 804-827-1427.
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Flores I, Benetti R, Blasco MA. Telomerase regulation and stem cell behaviour. Curr Opin Cell Biol 2006; 18:254-60. [PMID: 16617011 DOI: 10.1016/j.ceb.2006.03.003] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Accepted: 03/28/2006] [Indexed: 12/17/2022]
Abstract
Telomerase expression is restricted to a few cell types of the adult organism, most notably germ cells and stem/progenitor cells. Telomerase activity in germ cells is sufficient to prevent telomere shortening with age. Stem cells, however, do not have sufficient telomerase to prevent telomere shortening associated with continuous tissue renewal with increasing age. Indeed, telomerase levels in the adult organism are thought to be rate-limiting for longevity. This is supported by rare human syndromes caused by mutations in telomerase components, which are characterized by premature loss of tissue renewal and premature death. More recently, the role of telomerase and telomere length in stem cells is starting to be elucidated.
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Affiliation(s)
- Ignacio Flores
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), 28029 Madrid, Spain
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Bilsland AE, Stevenson K, Atkinson S, Kolch W, Keith WN. Transcriptional Repression of Telomerase RNA Gene Expression by c-Jun-NH2-Kinase and Sp1/Sp3. Cancer Res 2006; 66:1363-70. [PMID: 16452190 DOI: 10.1158/0008-5472.can-05-1941] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Telomerase is essential for immortalization of most human cancer cells. Expression of the core telomerase RNA (hTR) and reverse transcriptase (hTERT) subunits is mainly regulated by transcription. However, hTR transcriptional regulation remains poorly understood. We previously showed that the core hTR promoter is activated by Sp1 and is repressed by Sp3. Here, we show that the mitogen-activated protein kinase kinase kinase 1 (MEKK1)/c-Jun-NH(2)-kinase (JNK) pathway represses hTR expression by a mechanism that involves Sp1 and Sp3. Promoter activity was induced by the JNK inhibitor SP600125 and was repressed by activated MEKK1. Repression by MEKK1 was blocked by SP600125 or enhanced by coexpression of wild-type but not phosphoacceptor mutated JNK. SP600125 treatment also increased levels of endogenous hTR. Mutations in the hTR promoter Sp1/Sp3 binding sites attenuated SP600125-mediated promoter induction, whereas coexpression of MEKK1 with Sp3 enhanced hTR promoter repression. Chromatin immunoprecipitation showed that levels of immunoreactive Sp1 associated with the hTR promoter were low in comparison with Sp3 in control cells but increased after JNK inhibition with a reciprocal decrease in Sp3 levels. No corresponding changes in Sp1/Sp3 protein levels were detected. Thus, JNK represses hTR promoter activity and expression, apparently by enhancing repression through Sp3.
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Affiliation(s)
- Alan E Bilsland
- Centre for Oncology and Applied Pharmacology, University of Glasgow, Scotland, UK
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