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Abstract
Telomeres and their associated proteins protect the ends of chromosomes to maintain genome stability. Telomeres undergo progressive shortening with each cell division in mammalian somatic cells without telomerase, resulting in genome instability. When telomeres reach a critically short length or are recognized as a damage signal, cells enter a state of senescence, followed by cell cycle arrest, programmed cell death, or immortalization. This review provides an overview of recent advances in the intricate relationship between telomeres and genome instability. Alongside well-established mechanisms such as chromosomal fusion and telomere fusion, we will delve into the perspective on genome stability by examining the role of retrotransposons. Retrotransposons represent an emerging pathway to regulate genome stability through their interactions with telomeres.
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Affiliation(s)
- Xinyi Lu
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, Tianjin 300350, China.
| | - Lin Liu
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, Tianjin 300350, China; Frontiers Science Center for Cell Responses, College of Life Science, Nankai University, Tianjin, Tianjin 300071, China; Haihe Laboratory of Cell Ecosystem, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300020, China; Institute of Translational Medicine, Tianjin Union Medical Center, Nankai University, Tianjin 300000, China.
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Katoh H, Honda T. Roles of Human Endogenous Retroviruses and Endogenous Virus-Like Elements in Cancer Development and Innate Immunity. Biomolecules 2023; 13:1706. [PMID: 38136578 PMCID: PMC10741599 DOI: 10.3390/biom13121706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 11/18/2023] [Accepted: 11/21/2023] [Indexed: 12/24/2023] Open
Abstract
Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections in the host genome. Although mutations and silencing mechanisms impair their original role in viral replication, HERVs are believed to play roles in various biological processes. Long interspersed nuclear elements (LINEs) are non-LTR retrotransposons that have a lifecycle resembling that of retroviruses. Although LINE expression is typically silenced in somatic cells, it also contributes to various biological processes. The aberrant expression of HERVs and LINEs is closely associated with the development of cancer and/or immunological diseases, suggesting that they are integrated into various pathways related to the diseases. HERVs/LINEs control gene expression depending on the context as promoter/enhancer elements. Some RNAs and proteins derived from HERVs/LINEs have oncogenic potential, whereas others stimulate innate immunity. Non-retroviral endogenous viral elements (nrEVEs) are a novel type of virus-like element in the genome. nrEVEs may also be involved in host immunity. This article provides a current understanding of how these elements impact cellular physiology in cancer development and innate immunity, and provides perspectives for future studies.
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Affiliation(s)
- Hirokazu Katoh
- Department of Virology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan;
| | - Tomoyuki Honda
- Department of Virology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan;
- Department of Virology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
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Kalmykova AI, Sokolova OA. Retrotransposons and Telomeres. Biochemistry (Mosc) 2023; 88:1739-1753. [PMID: 38105195 DOI: 10.1134/s0006297923110068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/24/2023] [Accepted: 08/12/2023] [Indexed: 12/19/2023]
Abstract
Transposable elements (TEs) comprise a significant part of eukaryotic genomes being a major source of genome instability and mutagenesis. Cellular defense systems suppress the TE expansion at all stages of their life cycle. Piwi proteins and Piwi-interacting RNAs (piRNAs) are key elements of the anti-transposon defense system, which control TE activity in metazoan gonads preventing inheritable transpositions and developmental defects. In this review, we discuss various regulatory mechanisms by which small RNAs combat TE activity. However, active transposons persist, suggesting these powerful anti-transposon defense mechanisms have a limited capacity. A growing body of evidence suggests that increased TE activity coincides with genome reprogramming and telomere lengthening in different species. In the Drosophila fruit fly, whose telomeres consist only of retrotransposons, a piRNA-mediated mechanism is required for telomere maintenance and their length control. Therefore, the efficacy of protective mechanisms must be finely balanced in order not only to suppress the activity of transposons, but also to maintain the proper length and stability of telomeres. Structural and functional relationship between the telomere homeostasis and LINE1 retrotransposon in human cells indicates a close link between selfish TEs and the vital structure of the genome, telomere. This relationship, which permits the retention of active TEs in the genome, is reportedly a legacy of the retrotransposon origin of telomeres. The maintenance of telomeres and the execution of other crucial roles that TEs acquired during the process of their domestication in the genome serve as a type of payment for such a "service."
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Affiliation(s)
- Alla I Kalmykova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
| | - Olesya A Sokolova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, 119334, Russia
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Berteli TS, Wang F, Navarro PA, Kohlrausch FB, Keefe DL. A pilot study of LINE-1 copy number and telomere length with aging in human sperm. J Assist Reprod Genet 2023:10.1007/s10815-023-02857-1. [PMID: 37382785 PMCID: PMC10371944 DOI: 10.1007/s10815-023-02857-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 06/03/2023] [Indexed: 06/30/2023] Open
Abstract
PURPOSE Unlike other cells in the body, in sperm, telomere length (TL) increases with age. TL can regulate nearby genes, and the subtelomeric region is rich in retrotransposons. We hypothesized that age-related telomere lengthening in sperm might suppress Long Interspersed Element 1 (LINE-1/L1), the only competent retrotransposon in humans. METHODS We measured L1 copy number (L1-CN) and sperm telomere length (STL) from young and older men to evaluate the relationship between age, TL and L1-CN. We also evaluated L1-CN and TL in individual sperm to determine whether these variables influence sperm morphology. STL was assayed by Multiplex quantitative polymerase chain reaction method (mmqPCR) and L1-CN by Quantitative polymerase chain reaction (qPCR). RESULTS We found that STL increased, and L1-CN decreased significantly with paternal age. STL in normal single sperm was significantly higher than in abnormal sperm. L1-CN did not differ between normal and abnormal sperm. Furthermore, morphologically normal sperm have longer telomeres than abnormal sperm. CONCLUSIONS Elongation of telomeres in the male germline could repress retrotransposition, which tends to increase with cellular aging. More studies in larger cohorts across a wide age span are needed to confirm our conclusions and explore their biological and clinical significance.
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Affiliation(s)
- Thalita S Berteli
- Department of Obstetrics and Gynecology, Langone Medical Center, New York University, 462, 1st Avenue, New York, NY, 10016, USA.
- Human Reproduction Division, Department of Gynecology and Obstetrics, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil.
| | - Fang Wang
- Department of Obstetrics and Gynecology, Langone Medical Center, New York University, 462, 1st Avenue, New York, NY, 10016, USA
| | - Paula A Navarro
- Human Reproduction Division, Department of Gynecology and Obstetrics, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Fabiana B Kohlrausch
- Department of Obstetrics and Gynecology, Langone Medical Center, New York University, 462, 1st Avenue, New York, NY, 10016, USA
- Human Genetics Laboratory, Fluminense Federal University, Niteroi, RJ, Brazil
| | - David L Keefe
- Department of Obstetrics and Gynecology, Langone Medical Center, New York University, 462, 1st Avenue, New York, NY, 10016, USA
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Zhao N, Yin G, Liu C, Zhang W, Shen Y, Wang D, Lin Z, Yang J, Mao J, Guo R, Zhang Y, Wang F, Liu Z, Lu X, Liu L. Critically short telomeres derepress retrotransposons to promote genome instability in embryonic stem cells. Cell Discov 2023; 9:45. [PMID: 37130870 PMCID: PMC10154409 DOI: 10.1038/s41421-023-00538-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 03/08/2023] [Indexed: 05/04/2023] Open
Abstract
Telomeres, at the ends of chromosomes, protect chromosomes from fusion and preserve genomic stability. However, the molecular mechanisms underlying telomere attrition-induced genome instability remain to be understood. We systematically analyzed the expression of retrotransposons and performed genomic sequencing of different cell and tissue types with telomeres of varying lengths due to telomerase deficiency. We found that critically short telomeres altered retrotransposon activity to promote genomic instability in mouse embryonic stem cells, as evidenced by elevated numbers of single nucleotide variants, indels and copy number variations (CNVs). Transpositions of retrotransposons such as LINE1 resulting from the short telomeres can also be found in these genomes with elevated number of mutations and CNVs. Retrotransposon activation is linked to increased chromatin accessibility, and reduced heterochromatin abundance correlates with short telomeres. Re-elongation of telomeres upon recovery of telomerase partly represses retrotransposons and heterochromatin accumulation. Together, our findings suggest a potential mechanism by which telomeres maintain genomic stability by suppressing chromatin accessibility and retrotransposon activity.
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Affiliation(s)
- Nannan Zhao
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
- Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin, China
| | - Guoxing Yin
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
- Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin, China
| | - Chun Liu
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
- Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin, China
| | - Weiyu Zhang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
- College of Pharmacy, Nankai University, Tianjin, China
| | - Yang Shen
- Genome Institute of Singapore, Singapore, Singapore
| | - Dan Wang
- 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Key Laboratory of Medical Epigenetics, Department of Immunology, Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Zhenzhen Lin
- 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Key Laboratory of Medical Epigenetics, Department of Immunology, Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Jiao Yang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
- Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin, China
| | - Jian Mao
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
- Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin, China
| | - Renpeng Guo
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
- Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin, China
| | - Yongwang Zhang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China
- College of Pharmacy, Nankai University, Tianjin, China
| | - Feng Wang
- Department of Genetics, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Zhe Liu
- 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Key Laboratory of Medical Epigenetics, Department of Immunology, Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China.
| | - Xinyi Lu
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China.
- College of Pharmacy, Nankai University, Tianjin, China.
| | - Lin Liu
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China.
- Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin, China.
- Haihe Laboratory of Cell Ecosystem, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China.
- Institute of Translational Medicine, Tianjin Union Medical Center, Nankai University, Tianjin, China.
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Zadran B, Sudhindar PD, Wainwright D, Bury Y, Luli S, Howarth R, McCain MV, Watson R, Huet H, Palinkas F, Berlinguer-Palmini R, Casement J, Mann DA, Oakley F, Lunec J, Reeves H, Faulkner GJ, Shukla R. Impact of retrotransposon protein L1 ORF1p expression on oncogenic pathways in hepatocellular carcinoma: the role of cytoplasmic PIN1 upregulation. Br J Cancer 2023; 128:1236-1248. [PMID: 36707636 PMCID: PMC10050422 DOI: 10.1038/s41416-023-02154-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 01/09/2023] [Accepted: 01/11/2023] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Molecular characterisation of hepatocellular carcinoma (HCC) is central to the development of novel therapeutic strategies for the disease. We have previously demonstrated mutagenic consequences of Long-Interspersed Nuclear Element-1 (LINE1s/L1) retrotransposition. However, the role of L1 in HCC, besides somatic mutagenesis, is not well understood. METHODS We analysed L1 expression in the TCGA-HCC RNAseq dataset (n = 372) and explored potential relationships between L1 expression and clinical features. The findings were confirmed by immunohistochemical (IHC) analysis of an independent human HCC cohort (n = 48) and functional mechanisms explored using in vitro and in vivo model systems. RESULTS We observed positive associations between L1 and activated TGFβ-signalling, TP53 mutation, alpha-fetoprotein and tumour invasion. IHC confirmed a positive association between pSMAD3, a surrogate for TGFβ-signalling status, and L1 ORF1p (P < 0.0001, n = 32). Experimental modulation of L1 ORF1p levels revealed an influence of L1 ORF1p on key hepatocarcinogenesis-related pathways. Reduction in cell migration and invasive capacity was observed upon L1 ORF1 knockdown, both in vitro and in vivo. In particular, L1 ORF1p increased PIN1 cytoplasmic localisation. Blocking PIN1 activity abrogated L1 ORF1p-induced NF-κB-mediated inflammatory response genes while further activated TGFβ-signalling confirming differential alteration of PIN1 activity in cellular compartments by L1 ORF1p. DISCUSSION Our data demonstrate a causal link between L1 ORF1p and key oncogenic pathways mediated by PIN1, presenting a novel therapeutic avenue.
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Affiliation(s)
- Bassier Zadran
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Praveen Dhondurao Sudhindar
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Daniel Wainwright
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Yvonne Bury
- Department of Cellular Pathology, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle-upon-Tyne, UK
| | - Saimir Luli
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Rachel Howarth
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Misti Vanette McCain
- Newcastle University Centre for Cancer, Clinical and Translational Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Robyn Watson
- Newcastle University Centre for Cancer, Clinical and Translational Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Hannah Huet
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Fanni Palinkas
- Newcastle University Centre for Cancer, Clinical and Translational Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | | | - John Casement
- Bioinformatics Support Unit, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Derek A Mann
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
- Department of Gastroenterology and Hepatology, School of Medicine, Koç University, Istanbul, Turkey
| | - Fiona Oakley
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - John Lunec
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Helen Reeves
- Newcastle University Centre for Cancer, Clinical and Translational Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK
- Hepatopancreatobiliary Multidisciplinary Team, Freeman Hospital, Newcastle-upon-Tyne Hospitals NHS foundation, Newcastle-upon-Tyne, UK
| | - Geoffrey J Faulkner
- Mater Research Institute-University of Queensland, TRI Building, Woolloongabba, QLD, 4102, Australia
- Queensland Brain Institute, University of Queensland, Brisbane, QLD, 4072, Australia
| | - Ruchi Shukla
- Newcastle University Centre for Cancer, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, UK.
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle, Tyne and Wear, NE1 8ST, UK.
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Ward JR, Khan A, Torres S, Crawford B, Nock S, Frisbie T, Moran J, Longworth M. Condensin I and condensin II proteins form a LINE-1 dependent super condensin complex and cooperate to repress LINE-1. Nucleic Acids Res 2022; 50:10680-10694. [PMID: 36169232 PMCID: PMC9561375 DOI: 10.1093/nar/gkac802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/31/2022] [Accepted: 09/06/2022] [Indexed: 11/17/2022] Open
Abstract
Condensin I and condensin II are multi-subunit complexes that are known for their individual roles in genome organization and preventing genomic instability. However, interactions between condensin I and condensin II subunits and cooperative roles for condensin I and condensin II, outside of their genome organizing functions, have not been reported. We previously discovered that condensin II cooperates with Gamma Interferon Activated Inhibitor of Translation (GAIT) proteins to associate with Long INterspersed Element-1 (LINE-1 or L1) RNA and repress L1 protein expression and the retrotransposition of engineered L1 retrotransposition in cultured human cells. Here, we report that the L1 3'UTR is required for condensin II and GAIT association with L1 RNA, and deletion of the L1 RNA 3'UTR results in increased L1 protein expression and retrotransposition. Interestingly, like condensin II, we report that condensin I also binds GAIT proteins, associates with the L1 RNA 3'UTR, and represses L1 retrotransposition. We provide evidence that the condensin I protein, NCAPD2, is required for condensin II and GAIT protein association with L1 RNA. Furthermore, condensin I and condensin II subunits interact to form a L1-dependent super condensin complex (SCC) which is located primarily within the cytoplasm of both transformed and primary epithelial cells. These data suggest that increases in L1 expression in epithelial cells promote cytoplasmic condensin protein associations that facilitate a feedback loop in which condensins may cooperate to mediate L1 repression.
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Affiliation(s)
- Jacqueline R Ward
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Afshin Khan
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Sabrina Torres
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Bert Crawford
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Sarah Nock
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44195, USA
| | - Trenton Frisbie
- Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - John V Moran
- Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
- Internal Medicine, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Michelle S Longworth
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
- Cleveland Clinic Lerner College of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44195, USA
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McKerrow W, Wang X, Mendez-Dorantes C, Mita P, Cao S, Grivainis M, Ding L, LaCava J, Burns KH, Boeke JD, Fenyö D. LINE-1 expression in cancer correlates with p53 mutation, copy number alteration, and S phase checkpoint. Proc Natl Acad Sci U S A 2022; 119:e2115999119. [PMID: 35169076 DOI: 10.1073/pnas.2115999119] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2022] [Indexed: 12/12/2022] Open
Abstract
Retrotransposons are genomic DNA sequences that copy themselves to new genomic locations via RNA intermediates; LINE-1 is the only active and autonomous retrotransposon in the human genome. The mobility of LINE-1 is largely repressed in somatic tissues but is derepressed in many cancers, where LINE-1 retrotransposition is correlated with p53 mutation and copy number alteration (CNA). In cell lines, inducing LINE-1 expression can cause double-strand breaks (DSBs) and replication stress. Reanalyzing multiomic data from breast, ovarian, endometrial, and colon cancers, we confirmed correlations between LINE-1 expression, p53 mutation status, and CNA. We observed a consistent correlation between LINE-1 expression and the abundance of DNA replication complex components, indicating that LINE-1 may also induce replication stress in human tumors. In endometrial cancer, high-quality phosphoproteomic data allowed us to identify the DSB-induced ATM-MRN-SMC S phase checkpoint pathway as the primary DNA damage response (DDR) pathway associated with LINE-1 expression. Induction of LINE-1 expression in an in vitro model led to increased phosphorylation of MRN complex member RAD50, suggesting that LINE-1 directly activates this pathway.
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Mustafin RN. Relationship of Peptides and Long Non-Coding RNAs with Aging. Adv Gerontol 2021. [DOI: 10.1134/s2079057021040081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Aschacher T, Baranyi U, Aschacher O, Eichmair E, Messner B, Zimpfer D, Moayedifar R, Laufer G, Emmert MY, Sandner SE. A Novel Endothelial Damage Inhibitor Reduces Oxidative Stress and Improves Cellular Integrity in Radial Artery Grafts for Coronary Artery Bypass. Front Cardiovasc Med 2021; 8:736503. [PMID: 34692789 PMCID: PMC8527012 DOI: 10.3389/fcvm.2021.736503] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 09/07/2021] [Indexed: 11/13/2022] Open
Abstract
The radial artery (RA) is a frequently used conduit in coronary artery bypass grafting (CABG). Endothelial injury incurred during graft harvesting promotes oxidative damage, which leads to graft disease and graft failure. We evaluated the protective effect of DuraGraft®, an endothelial damage inhibitor (EDI), on RA grafts. We further compared the protective effect of the EDI between RA grafts and saphenous vein grafts (SVG). Samples of RA (n = 10) and SVG (n = 13) from 23 patients undergoing CABG were flushed and preserved with either EDI or heparinized Ringer's lactate solution (RL). The effect of EDI vs. RL on endothelial damage was evaluated ex vivo and in vitro using histological analysis, immunofluorescence staining, Western blot, and scanning electron microscopy. EDI-treated RA grafts showed a significant reduction of endothelial and sub-endothelial damage. Lower level of reactive oxygen species (ROS) after EDI treatment was correlated with a reduction of hypoxic damage (eNOS and Caveolin-1) and significant increase of oxidation-reduction potential. Additionally, an increased expression of TGFβ, PDGFα/β, and HO-1 which are indicative for vascular protective function were observed after EDI exposure. EDI treatment preserves functionality and integrity of endothelial and intimal cells. Therefore, EDI may have the potential to reduce the occurrence of graft disease and failure in RA grafts in patients undergoing CABG.
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Affiliation(s)
- Thomas Aschacher
- Department of Cardio-Vascular Surgery, Clinic Floridsdorf and Karl Landsteiner Institute for Cardio-Vascular Research, Vienna, Austria.,Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Ulrike Baranyi
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Olivia Aschacher
- Department of Plastic, Reconstructive and Plastic Surgery, Medical University Vienna, Vienna, Austria
| | - Eva Eichmair
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Barbara Messner
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Daniel Zimpfer
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Roxana Moayedifar
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Guenther Laufer
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Maximilian Y Emmert
- Cardiovascular Surgery, Charite-Universitätsmedizin Berlin, Berlin, Germany.,Department of Cardiothoracic and Vascular Surgery, German Heart Institute Berlin, Berlin, Germany
| | - Sigrid E Sandner
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
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Morgunova V, Kordyukova M, Mikhaleva EA, Butenko I, Pobeguts OV, Kalmykova A. Loss of telomere silencing is accompanied by dysfunction of Polo kinase and centrosomes during Drosophila oogenesis and early development. PLoS One 2021; 16:e0258156. [PMID: 34624021 DOI: 10.1371/journal.pone.0258156] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 09/18/2021] [Indexed: 12/03/2022] Open
Abstract
Telomeres are nucleoprotein complexes that protect the ends of eukaryotic linear chromosomes from degradation and fusions. Telomere dysfunction leads to cell growth arrest, oncogenesis, and premature aging. Telomeric RNAs have been found in all studied species; however, their functions and biogenesis are not clearly understood. We studied the mechanisms of development disorders observed upon overexpression of telomeric repeats in Drosophila. In somatic cells, overexpression of telomeric retrotransposon HeT-A is cytotoxic and leads to the accumulation of HeT-A Gag near centrosomes. We found that RNA and RNA-binding protein Gag encoded by the telomeric retrotransposon HeT-A interact with Polo and Cdk1 mitotic kinases, which are conserved regulators of centrosome biogenesis and cell cycle. The depletion of proteins Spindle E, Ccr4 or Ars2 resulting in HeT-A overexpression in the germline was accompanied by mislocalization of Polo as well as its abnormal stabilization during oogenesis and severe deregulation of centrosome biogenesis leading to maternal-effect embryonic lethality. These data suggest a mechanistic link between telomeric HeT-A ribonucleoproteins and cell cycle regulators that ensures the cell response to telomere dysfunction.
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Rusetska N, Kober P, Król SK, Boresowicz J, Maksymowicz M, Kunicki J, Bonicki W, Bujko M. Invasive and Noninvasive Nonfunctioning Gonadotroph Pituitary Tumors Differ in DNA Methylation Level of LINE-1 Repetitive Elements. J Clin Med 2021; 10:560. [PMID: 33546126 PMCID: PMC7913198 DOI: 10.3390/jcm10040560] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/22/2021] [Accepted: 01/26/2021] [Indexed: 12/11/2022] Open
Abstract
PURPOSE Epigenetic dysregulation plays a role in pituitary tumor pathogenesis. Some differences in DNA methylation were observed between invasive and noninvasive nonfunctioning gonadotroph tumors. This study sought to determine the role of DNA methylation changes in repetitive LINE-1 elements in nonfunctioning gonadotroph pituitary tumors. METHODS We investigated LINE-1 methylation levels in 80 tumors and normal pituitary glands with bisulfite-pyrosequencing. Expression of two LINE-1 open reading frames (L1-ORF1 and L1-ORF2) was analyzed with qRT-PCR in tumor samples and mouse gonadotroph pituitary cells treated with DNA methyltransferase inhibitor. Immunohistochemical staining against L1-ORF1p was also performed in normal pituitary glands and tumors. RESULTS Hypomethylation of LINE-1 was observed in pituitary tumors. Tumors characterized by invasive growth revealed lower LINE-1 methylation level than noninvasive ones. LINE-1 methylation correlated with overall DNA methylation assessed with HM450K arrays and negatively correlated with L1-ORF1 and L1-ORF2 expression. Treatment of αT3-1 gonadotroph cells with 5-Azacytidine clearly increased the level of L1-ORF1 and L1-ORF2 mRNA; however, its effect on LβT2 cells was less pronounced. Immunoreactivity against L1-ORF1p was higher in tumors than normal tissue. No difference in L1-ORF1p expression was observed in invasive and noninvasive tumors. CONCLUSION Hypomethylation of LINE-1 is related to invasive growth and influences transcriptional activity of transposable elements.
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Affiliation(s)
- Natalia Rusetska
- Department of Molecular and Translational Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland; (N.R.); (P.K.); (S.K.K.); (J.B.)
| | - Paulina Kober
- Department of Molecular and Translational Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland; (N.R.); (P.K.); (S.K.K.); (J.B.)
| | - Sylwia Katarzyna Król
- Department of Molecular and Translational Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland; (N.R.); (P.K.); (S.K.K.); (J.B.)
| | - Joanna Boresowicz
- Department of Molecular and Translational Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland; (N.R.); (P.K.); (S.K.K.); (J.B.)
| | - Maria Maksymowicz
- Department of Pathology and Laboratory Diagnostics, Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland;
| | - Jacek Kunicki
- Department of Neurosurgery, Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland; (J.K.); (W.B.)
| | - Wiesław Bonicki
- Department of Neurosurgery, Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland; (J.K.); (W.B.)
| | - Mateusz Bujko
- Department of Molecular and Translational Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland; (N.R.); (P.K.); (S.K.K.); (J.B.)
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14
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Chen K, Li L, Qu S, Pan X, Sun Y, Wan F, Yu B, Zhou L, Zhu X. Silencing hTERT attenuates cancer stem cell-like characteristics and radioresistance in the radioresistant nasopharyngeal carcinoma cell line CNE-2R. Aging (Albany NY) 2020; 12:25599-613. [PMID: 33234740 DOI: 10.18632/aging.104167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 09/18/2020] [Indexed: 12/21/2022]
Abstract
Objective: This study aimed to explore the effect of silencing hTERT on the CSC-like characteristics and radioresistance of CNE-2R cells. Results: Silencing hTERT suppressed CNE-2R cell proliferation and increased the cell apoptosis rate and radiosensitivity in vitro. Moreover, it could also inhibit the growth of xenografts and increase the apoptosis index and radiosensitivity in vivo. Further study discovered that after silencing hTERT, telomerase activity in CNE-2R cells was markedly suppressed, along with remarkably down-regulated stem cell-related protein levels both in vitro and in vivo. Conclusion: Silencing hTERT can suppress the CSC-like characteristics of CNE-2R cells to enhance their radiosensitivity, revealing that hTERT may become a potential target for treating radioresistant NPC. Methods: An RNAi lentiviral vector specific to the hTERT gene was constructed to infect CNE-2R cells, the hTERT silencing effect was verified through qPCR and Western blot assays, and telomerase activity was detected by PCR-ELISA. Moreover, radiosensitivity in vitro was detected through colony formation assays, CCK-8 assays and flow cytometry. Tumor growth and radioresistance were also evaluated using xenograft models, while the apoptosis index in xenografts was measured through TUNEL assay. Levels of stem cell-related proteins were determined in vitro and in vivo.
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15
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Ahuja A, Journo G, Eitan R, Rubin E, Shamay M. High levels of LINE-1 transposable elements expressed in Kaposi's sarcoma-associated herpesvirus-related primary effusion lymphoma. Oncogene 2021; 40:536-50. [PMID: 33188297 DOI: 10.1038/s41388-020-01549-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 10/13/2020] [Accepted: 10/28/2020] [Indexed: 11/08/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV, HHV-8) is a gamma herpesvirus associated with several human malignancies. Transposable elements (TEs) are ubiquitous in eukaryotic genomes, occupying about 45% of the human genome. TEs have been linked with a variety of disorders and malignancies, though the precise nature of their contribution to many of them has yet to be elucidated. Global transcriptome analysis for differentially expressed TEs in KSHV-associated primary effusion lymphoma (PEL) cells (BCBL1 and BC3) revealed large number of differentially expressed TEs. These differentially expressed TEs include LTR transposons, long interspersed nuclear elements (LINEs), and short interspersed nuclear elements (SINEs). Further analysis of LINE-1 (L1) elements revealed expression upregulation, hypo-methylation, and transition into open chromatin in PEL. In agreement with high L1 expression, PEL cells express ORF1 protein and possess high reverse transcriptase (RT)-activity. Interestingly, inhibition of this RT-activity suppressed PEL cell growth. Collectively, we identified high expression of TEs, and specifically of L1 as a critical component in the proliferation of PEL cells. This observation is relevant for the treatment of KSHV-associated malignancies since they often develop in AIDS patients that are treated with RT inhibitors with potent inhibition for both HIV and L1 RT activity.
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16
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Marasca F, Gasparotto E, Polimeni B, Vadalà R, Ranzani V, Bodega B. The Sophisticated Transcriptional Response Governed by Transposable Elements in Human Health and Disease. Int J Mol Sci 2020; 21:ijms21093201. [PMID: 32366056 PMCID: PMC7247572 DOI: 10.3390/ijms21093201] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 04/29/2020] [Accepted: 04/29/2020] [Indexed: 01/15/2023] Open
Abstract
Transposable elements (TEs), which cover ~45% of the human genome, although firstly considered as “selfish” DNA, are nowadays recognized as driving forces in eukaryotic genome evolution. This capability resides in generating a plethora of sophisticated RNA regulatory networks that influence the cell type specific transcriptome in health and disease. Indeed, TEs are transcribed and their RNAs mediate multi-layered transcriptional regulatory functions in cellular identity establishment, but also in the regulation of cellular plasticity and adaptability to environmental cues, as occurs in the immune response. Moreover, TEs transcriptional deregulation also evolved to promote pathogenesis, as in autoimmune and inflammatory diseases and cancers. Importantly, many of these findings have been achieved through the employment of Next Generation Sequencing (NGS) technologies and bioinformatic tools that are in continuous improvement to overcome the limitations of analyzing TEs sequences. However, they are highly homologous, and their annotation is still ambiguous. Here, we will review some of the most recent findings, questions and improvements to study at high resolution this intriguing portion of the human genome in health and diseases, opening the scenario to novel therapeutic opportunities.
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Affiliation(s)
- Federica Marasca
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
| | - Erica Gasparotto
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
| | - Benedetto Polimeni
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
| | - Rebecca Vadalà
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
- Translational and Molecular Medicine, DIMET, University of Milan-Bicocca, 20900 Monza, Italy
| | - Valeria Ranzani
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
| | - Beatrice Bodega
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
- Correspondence:
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17
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Zhang HH, Zhao LD, Zuo P, Yin BC, Ye BC. A telomerase-responsive nanoprobe with theranostic properties in tumor cells. Talanta 2020; 215:120898. [PMID: 32312443 DOI: 10.1016/j.talanta.2020.120898] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/01/2020] [Accepted: 03/03/2020] [Indexed: 12/11/2022]
Abstract
Multidrug resistance (MDR) is the main cause of treatment failure in clinical cancer chemotherapy due to the presence of P-glycoproteins (P-gp), which widely exist in stubborn drug-resistant tumor membranes and actively pump drugs from inside the tumor cell to the outside. In this study, we report a novel telomerase-responsive nanoprobe with theranostic properties for inhibiting P-gp expression and reversing MDR by gene silencing. This nanoprobe is composed of an AuNP assembled with telomerase primer, antisense oligonucleotide (ASO), and doxorubicin (Dox). When the designed nanoprobe is uptaken by the MDR cancer cells, the Dox and ASO are specifically released due to the extension of telomerase primer triggered by telomerase. The released ASO specifically hybridizes with multidrug resistance 1 (MDR1) mRNA sequence, which encodes the P-gp. As a result, the expression of P-gp is inhibited and the efflux of Dox is prevented with reduced MDR in cancerous cells. The results demonstrate that the nanoprobe based on telomerase switching for drug release and gene silencing, can both target cancer cells for delivering drugs and overcome the effect of efflux pumps. This work presents a novel paradigm for theranostics of MDR cancer and enhances the efficacy of chemotherapeutics.
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Affiliation(s)
- He-Hua Zhang
- Lab of Biosystem and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Li-Dong Zhao
- Lab of Biosystem and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Peng Zuo
- Lab of Biosystem and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Bin-Cheng Yin
- Lab of Biosystem and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China; Institute of Engineering Biology and Health, Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China; School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, 832000, Xinjiang, China.
| | - Bang-Ce Ye
- Lab of Biosystem and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China; Institute of Engineering Biology and Health, Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China; School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, 832000, Xinjiang, China.
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18
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Dai W, Wu J, Wang D, Wang J. Cancer gene therapy by NF-κB-activated cancer cell-specific expression of CRISPR/Cas9 targeting telomeres. Gene Ther 2020; 27:266-280. [DOI: 10.1038/s41434-020-0128-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 01/22/2020] [Accepted: 01/28/2020] [Indexed: 02/07/2023]
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19
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Aschacher T, Wolf B, Aschacher O, Enzmann F, Laszlo V, Messner B, Türkcan A, Weis S, Spiegl-Kreinecker S, Holzmann K, Laufer G, Ehrlich M, Bergmann M. Long interspersed element-1 ribonucleoprotein particles protect telomeric ends in alternative lengthening of telomeres dependent cells. Neoplasia 2019; 22:61-75. [PMID: 31846834 PMCID: PMC6920197 DOI: 10.1016/j.neo.2019.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 12/21/2022] Open
Abstract
Malignant cells ensure telomere maintenance by the alternative lengthening of telomeres (ALT) in the absence of telomerase activity (TA). The retrotransposons "long interspersed nuclear element-1" (LINE-1, L1) are expressed in malignant cells and are primarily known to contribute to complex karyotypes. Here we demonstrate that LINE-1 ribonucleoprotein particles (L1-RNPs) expression is significantly higher in ALT+- versus in TA+-human glioma. Analyzing a role of L1-RNP in ALT, we show that L1-RNPs bind to telomeric repeat containing RNA (TERRA), which is critical for telomere stabilization and which is overexpressed in ALT+ cells. In turn, L1-RNP knockdown (KD) abrogated the nuclear retention of TERRA, resulted in increased telomeric DNA damage, decreased cell growth and reduced expression of ALT characteristics such as c-circles and PML-bodies. L1-RNP KD also decreased the expression of Shelterin- and the ALT-regulating protein Topoisomerase IIIα (TopoIIIα) indicating a more general role of L1-RNPs in supporting telomeric integrity in ALT. Our findings suggest an impact of L1-RNP on telomere stability in ALT+ dependent tumor cells. As L1-RNPs are rarely expressed in normal adult human tissue those elements might serve as a novel target for tumor ablative therapy.
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Affiliation(s)
- Thomas Aschacher
- Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Brigitte Wolf
- Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Olivia Aschacher
- Department of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Florian Enzmann
- Department of Vascular and Endovascular Surgery, Paracelsus Medical University Salzburg, Muellner Hauptstraße 48, 5020 Salzburg, Austria
| | - Viktoria Laszlo
- Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Barbara Messner
- Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Adrian Türkcan
- Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Serge Weis
- Division of Neuropathology, Neuromed Campus, Kepler University Hospital, 4020 Linz, Austria
| | - Sabine Spiegl-Kreinecker
- University Clinic for Neurosurgery, Neuromed Campus, Kepler University Hospital, Johannes Kepler University, Linz, Austria
| | - Klaus Holzmann
- Department of Cancer Research, Borschkegasse 8a, 1090 Vienna, Austria; Comprehensive Cancer Centre, Medical University of Vienna, Austria
| | - Günther Laufer
- Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Marek Ehrlich
- Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Michael Bergmann
- Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria; Comprehensive Cancer Centre, Medical University of Vienna, Austria.
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20
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Fotouhi O, Ghaderi M, Wang N, Zedenius J, Kjellman M, Xu D, Juhlin CC, Larsson C. Telomerase activation in small intestinal neuroendocrine tumours is associated with aberrant TERT promoter methylation, but not hot-spot mutations. Epigenetics 2019; 14:1224-1233. [PMID: 31322481 DOI: 10.1080/15592294.2019.1634987] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Telomere maintenance is a critical requirement for enabling replicative immortality and tumour development. Here, telomerase expression and activity, telomere length (TL) and potential regulatory factors that can underlie telomerase machinery alterations in small intestinal neuroendocrine tumours (SI-NETs) were analyzed. Telomerase activity assessed by TRAP assay was increased in SI-NETs compared to normal ileum (P < 0.001). The telomerase reverse transcriptase gene (TERT) was over-expressed in SI-NETs vs. normal ileal samples (P = 0.01). Furthermore, relative TL assessed by qPCR was found shorter in tumours compared with normal ileum (P = 0.02) and in distant metastasis samples compared to primary tumours and local metastases (P= 0.02). TERT promoter hotspot mutations were not present and TERT copy number gain was only observed in 3/70 tumour samples. TERT or chromosome 18 copy number alterations were not associated with telomerase expression and activity or TL. However, hypermethylation of TERT promoter in Region B - in the proximity of the transcription start site - was inversely correlated with TERT expression and telomerase activity and positively correlated with TL. Global LINE1 methylation was positively correlated with TERT promoter Region B methylation and was inversely correlated with telomerase activity, TERT expression and the upstream Region A methylation. The results show that telomerase activation, TERT expression and shorter telomeres are commonly found in SI-NETs. Aberrant DNA methylation of TERT promoter and of LINE1 can be implicated in abnormal regulation of TERT in SI-NETs.
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Affiliation(s)
- Omid Fotouhi
- Department of Oncology-Pathology, Karolinska Institutet , Stockholm , Sweden
| | - Mehran Ghaderi
- Department of Oncology-Pathology, Karolinska Institutet , Stockholm , Sweden
| | - Na Wang
- Department of Oncology-Pathology, Karolinska Institutet , Stockholm , Sweden.,Cancer Center Karolinska,CCK
| | - Jan Zedenius
- Department of Molecular Medicine and Surgery, Karolinska Institutet , Stockholm , Sweden.,Department of Breast, Endocrine Tumours and Sarcoma, Karolinska University Hospital , Stockholm , Sweden
| | - Magnus Kjellman
- Department of Molecular Medicine and Surgery, Karolinska Institutet , Stockholm , Sweden.,Department of Breast, Endocrine Tumours and Sarcoma, Karolinska University Hospital , Stockholm , Sweden
| | - Dawei Xu
- Department of Medicine, Division of Hematology (D.X.), Karolinska University Hospital , Stockholm , Sweden
| | - C Christofer Juhlin
- Department of Oncology-Pathology, Karolinska Institutet , Stockholm , Sweden.,Cancer Center Karolinska,CCK
| | - Catharina Larsson
- Department of Oncology-Pathology, Karolinska Institutet , Stockholm , Sweden.,Cancer Center Karolinska,CCK
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21
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Dai W, Xu X, Wang D, Wu J, Wang J. Cancer therapy with a CRISPR-assisted telomerase-activating gene expression system. Oncogene 2019; 38:4110-4124. [PMID: 30696954 DOI: 10.1038/s41388-019-0707-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 01/07/2019] [Accepted: 01/15/2019] [Indexed: 12/13/2022]
Abstract
Cancer is caused by a series of alterations in genome and epigenome and exists in multiple complex forms, making it difficult to be prevented and/or treated. Telomerase, an enzyme responsible for the maintenance of telomere, is silent in most normal somatic cells but activated in 90% of cancer cells, making it an excellent target for cancer therapy. Therefore, various telomerase activity inhibitors have been developed to treat cancer but all failed due to side effects. Here we acted oppositely to develop a cancer gene therapy named telomerase-activating gene expression (Tage) system by utilizing the telomerase activity in cancer cells. The Tage system consisted of an effector gene expression vector that carried a 3' telomerase-recognizable stick end and an artificial transcription factor expression vector that could express dCas9-VP64 and an sgRNA targeting telomere repeat sequences. By using Cas9 as an effector gene, the Tage system effectively killed various cancer cells, including HepG2, HeLa, PANC-1, MDA-MB-453, A549, HT-29, SKOV-3, Hepa1-6, and RAW264.7, without affecting normal cells MRC-5, HL7702, and bone marrow mesenchymal stem cell (BMSC). More importantly, a four-base 3' stick end produced by the homothallic switching endonuclease in cells could be recognized by telomerase, allowing the Tage system to effectively kill cancer cells in vivo. The Tage system could effectively and safely realize its in vivo application by using adeno-associated virus (AAV) as gene vector. The virus-loaded Tage system could significantly and specifically kill cancer cells in mice by intravenous drug administration without side effects or toxicity.
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Affiliation(s)
- Wei Dai
- State Key Laboratory of Bioelectronics, Southeast University, 210096, Nanjing, China
| | - Xinhui Xu
- State Key Laboratory of Bioelectronics, Southeast University, 210096, Nanjing, China
| | - Danyang Wang
- State Key Laboratory of Bioelectronics, Southeast University, 210096, Nanjing, China
| | - Jian Wu
- State Key Laboratory of Bioelectronics, Southeast University, 210096, Nanjing, China
| | - Jinke Wang
- State Key Laboratory of Bioelectronics, Southeast University, 210096, Nanjing, China.
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22
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Orqueda AJ, Gatti CR, Ogara MF, Falzone TL. SOX-11 regulates LINE-1 retrotransposon activity during neuronal differentiation. FEBS Lett 2018; 592:3708-3719. [PMID: 30276805 DOI: 10.1002/1873-3468.13260] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 09/20/2018] [Accepted: 09/22/2018] [Indexed: 01/25/2023]
Abstract
Activity of the human long interspersed nuclear elements-1 (LINE-1) retrotransposon occurs mainly in early embryonic development and during hippocampal neurogenesis. SOX-11, a transcription factor relevant to neuronal development, has unknown functions in the control of LINE-1 retrotransposon activity during neuronal differentiation. To study the dependence of LINE-1 activity on SOX-11 during neuronal differentiation, we induced differentiation of human SH-SY5Y neuroblastoma cells and adult adipose mesenchymal stem cells (hASCs) to a neuronal fate and found increased LINE-1 activity. We also show that SOX-11 protein binding to the LINE-1 promoter is higher in differentiating neuroblastoma cells, while knock-down of SOX-11 inhibits the induction of LINE-1 transcription in differentiating conditions. These results suggest that activation of LINE-1 retrotransposition during neuronal differentiation is mediated by SOX-11.
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Affiliation(s)
- Andrés J Orqueda
- Instituto de Medicina Traslacional e Ingeniería Biomédica (IMTIB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Hospital Italiano de Buenos Aires e Instituto Universitario del Hospital Italiano, Buenos Aires, Argentina
| | - Cintia R Gatti
- Instituto de Medicina Traslacional e Ingeniería Biomédica (IMTIB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Hospital Italiano de Buenos Aires e Instituto Universitario del Hospital Italiano, Buenos Aires, Argentina
| | - María F Ogara
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET-UBA), FCEN, UBA, Buenos Aires, Argentina
| | - Tomás L Falzone
- Instituto de Biología Celular y Neurociencias (IBCN-CONICET-UBA), Facultad de Medicina, UBA, Buenos Aires, Argentina.,Instituto de Biología y Medicina Experimental (IBYME-CONICET), Buenos Aires, Argentina
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23
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Jaguva Vasudevan AA, Kreimer U, Schulz WA, Krikoni A, Schumann GG, Häussinger D, Münk C, Goering W. APOBEC3B Activity Is Prevalent in Urothelial Carcinoma Cells and Only Slightly Affected by LINE-1 Expression. Front Microbiol 2018; 9:2088. [PMID: 30233553 PMCID: PMC6132077 DOI: 10.3389/fmicb.2018.02088] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 08/15/2018] [Indexed: 12/20/2022] Open
Abstract
The most common mutational signature in urothelial carcinoma (UC), the most common type of urinary bladder cancer is assumed to be caused by the misdirected activity of APOBEC3 (A3) cytidine deaminases, especially A3A or A3B, which are known to normally restrict the propagation of exogenous viruses and endogenous retroelements such as LINE-1 (L1). The involvement of A3 proteins in urothelial carcinogenesis is unexpected because, to date, UC is thought to be caused by chemical carcinogens rather than viral activity. Therefore, we explored the relationship between A3 expression and L1 activity, which is generally upregulated in UC. We found that UC cell lines highly express A3B and in some cases A3G, but not A3A, and exhibit corresponding cytidine deamination activity in vitro. While we observed evidence suggesting that L1 expression has a weak positive effect on A3B and A3G expression and A3B promoter activity, neither efficient siRNA-mediated knockdown nor overexpression of functional L1 elements affected catalytic activity of A3 proteins consistently. However, L1 knockdown diminished proliferation of a UC cell line exhibiting robust endogenous L1 expression, but had little impact on a cell line with low L1 expression levels. Our results indicate that UC cells express A3B at levels exceeding A3A levels by far, making A3B the prime candidate for causing genomic mutations. Our data provide evidence that L1 activation constitutes only a minor and negligible factor involved in induction or upregulation of endogenous A3 expression in UC.
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Affiliation(s)
- Ananda Ayyappan Jaguva Vasudevan
- Department of Urology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Ulrike Kreimer
- Department of Urology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Wolfgang A Schulz
- Department of Urology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Aikaterini Krikoni
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Gerald G Schumann
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Carsten Münk
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Wolfgang Goering
- Department of Urology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,Institute of Pathology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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Yu Y, Zhou L, Yang Y, Liu Y. Cycloastragenol: An exciting novel candidate for age-associated diseases. Exp Ther Med 2018; 16:2175-2182. [PMID: 30186456 PMCID: PMC6122403 DOI: 10.3892/etm.2018.6501] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 06/25/2018] [Indexed: 12/26/2022] Open
Abstract
Cycloastragenol (CAG) is a triterpenoid saponin compound and a hydrolysis product of the main active ingredient in Astragalus membranaceus (Fisch.) Bunge. An increasing body of evidence has indicated that CAG has a wide spectrum of pharmacological functions, which are attracting attention in the research community. The aim of the present review paper was to review and elucidate the advanced study of CAG. The focus was on advanced studies of CAG in English and Chinese databases; the literature was collected and reviewed to summarize the latest efficacy, pharmacokinetics and adverse reactions of CAG. Extensive pharmacological effects have been attributed to CAG, including telomerase activation, telomere elongation, anti-inflammatory and anti-oxidative properties; CAG has also been reported to improve lipid metabolism. Clinical research has demonstrated that CAG activates telomerase in humans and ameliorates various biomarkers. CAG is absorbed through the intestinal epithelium via passive diffusion and undergoes first-pass hepatic metabolism. Within a certain dose range, oral CAG is relatively safe; however, underlying mechanisms associated with CAG are not clear, and thus, we should be aware of potential adverse reactions associated with CAG. According to existing studies and clinical trials, CAG is safe and has broad application prospects. However, further studies are required to fully understand its efficacy and potential adverse reactions, and to ensure the proper use of CAG is applied to treat diseases clinically.
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Affiliation(s)
- Yongjie Yu
- Department of Pharmacology, Guangdong Medical University, Zhanjiang, Guangdong 524023, P.R. China
| | - Limin Zhou
- Department of Pharmacology, Guangdong Medical University, Zhanjiang, Guangdong 524023, P.R. China
| | - Yajun Yang
- Department of Pharmacology, Guangdong Medical University, Zhanjiang, Guangdong 524023, P.R. China
| | - Yuyu Liu
- Department of Pharmacology, Guangdong Medical University, Zhanjiang, Guangdong 524023, P.R. China.,Guangdong Key Laboratory for Research and Development of Natural Drugs, Guangdong Medical University, Zhanjiang, Guangdong 524023, P.R. China
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25
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Kordyukova M, Olovnikov I, Kalmykova A. Transposon control mechanisms in telomere biology. Curr Opin Genet Dev 2018; 49:56-62. [DOI: 10.1016/j.gde.2018.03.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 01/26/2018] [Accepted: 03/08/2018] [Indexed: 11/23/2022]
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26
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Guzman H, Sanders K, Idica A, Bochnakian A, Jury D, Daugaard I, Zisoulis DG, Pedersen IM. miR-128 inhibits telomerase activity by targeting TERT mRNA. Oncotarget 2018; 9:13244-13253. [PMID: 29568354 PMCID: PMC5862575 DOI: 10.18632/oncotarget.24284] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 01/09/2018] [Indexed: 01/28/2023] Open
Abstract
Telomerase is a unique cellular reverse transcriptase (RT) essential for maintaining telomere stability and required for the unlimited proliferation of cancer cells. The limiting determinant of telomerase activity is the catalytic component TERT, and TERT expression is closely correlated with telomerase activity and cancer initiation and disease progression. For this reason the regulation of TERT levels in the cell is of great importance. microRNAs (miRs) function as an additional regulatory level in cells, crucial for defining expression boundaries, proper cell fate decisions, cell cycle control, genome integrity, cell death and metastasis. We performed an anti-miR library screen to identity novel miRs, which participate in the control of telomerase. We identified the tumor suppressor miR (miR-128) as a novel endogenous telomerase inhibitor and determined that miR-128 significantly reduces the mRNA and protein levels of Tert in a panel of cancer cell lines. We further evaluated the mechanism by which miR-128 regulates TERT and demonstrated that miR-128 interacts directly with the coding sequence of TERT mRNA in both HeLa cells and teratoma cells. Interestingly, the functional miR-128 binding site in TERT mRNA, is conserved between TERT and the other cellular reverse transcriptase encoded by Long Interspersed Elements-1 (LINE-1 or L1), which can also contribute to the oncogenic phenotype of cancer. This finding supports the novel idea that miRs may function in parallel pathways to inhibit tumorigenesis, by regulating a group of enzymes (such as RT) by targeting conserved binding sites in the coding region of both enzymes.
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Affiliation(s)
- Herlinda Guzman
- Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine 92697-3900, CA, USA
| | - Katie Sanders
- Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine 92697-3900, CA, USA
| | - Adam Idica
- Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine 92697-3900, CA, USA
| | - Aurore Bochnakian
- Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine 92697-3900, CA, USA
| | - Douglas Jury
- Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine 92697-3900, CA, USA
| | - Iben Daugaard
- Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine 92697-3900, CA, USA
| | - Dimitrios G Zisoulis
- Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine 92697-3900, CA, USA
| | - Irene Munk Pedersen
- Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine 92697-3900, CA, USA
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27
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Pang T, Zhou M, Liu R, Luo J, Xia R. TERT rs2736098 (Ex2-659G>A) polymorphism and cancer susceptibility: evidence from a comprehensive meta-analysis. Oncotarget 2017; 8:96433-96441. [PMID: 29221218 PMCID: PMC5707112 DOI: 10.18632/oncotarget.21703] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 09/20/2017] [Indexed: 02/07/2023] Open
Abstract
Increasing researches have been performed regarding the relationship between TERT rs2736098 and cancer risk, but no consensus has been reached about the relationship. Here, we conducted this updated meta-analysis, aiming to comprehensively evaluate the role of TERT rs2736098 in cancer risk. We systematically searched potential relevant articles through PubMed, EMBASE, CNKI, and WanFang database before August 2017. A total of 33 studies with 18685 cases and 23820 controls were finally included in the current meta-analysis. We then adopted odds ratios (ORs) and 95% confidence intervals (CIs) to analyze the contributions of TERT rs2736098 to cancer risk. We found that the TERT rs2736098 polymorphism was associated with risk of cancer in overall analysis (AA vs. GG: OR = 1.26, 95% CI = 1.09–1.47; AA vs. AG/GG: OR = 1.22, 95% CI = 1.09–1.36; AA/AG vs. GG: OR = 1.13, 95% CI = 1.02–1.24; A vs. G: OR = 1.11, 95% CI = 1.04–1.20). Furthermore, in analysis stratified by cancer type, ethnicity, control source, quality score, and Hardy-Weinberg equilibrium (HWE) in controls, we found increased risk of cancer among lung cancer, bladder cancer, breast cancer, colorectal cancer, other cancers, Asians, hospital-based subgroup, score > 9 group, as well as controls agreement with HWE group. Despite some limitations, the current meta-analysis represented the largest and the most comprehensive investigations, with the strongest conclusion than ever before. To further explicit the association between TERT rs2736098 and cancer risk, more well-design case-control studies with larger sample size are warranted in the future.
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Affiliation(s)
- Tingyuan Pang
- Department of Pharmacy, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou City, 510000, P.R. China
| | - Minjie Zhou
- Department of Kidney Transplantation, Nanfang Hospital, Southern Medical University, Guangzhou City, 510000, P.R. China
| | - Rumin Liu
- Department of Kidney Transplantation, Nanfang Hospital, Southern Medical University, Guangzhou City, 510000, P.R. China
| | - Jia Luo
- Department of Kidney Transplantation, Nanfang Hospital, Southern Medical University, Guangzhou City, 510000, P.R. China
| | - Renfei Xia
- Department of Kidney Transplantation, Nanfang Hospital, Southern Medical University, Guangzhou City, 510000, P.R. China
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28
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Guler GD, Tindell CA, Pitti R, Wilson C, Nichols K, KaiWai Cheung T, Kim HJ, Wongchenko M, Yan Y, Haley B, Cuellar T, Webster J, Alag N, Hegde G, Jackson E, Nance TL, Giresi PG, Chen KB, Liu J, Jhunjhunwala S, Settleman J, Stephan JP, Arnott D, Classon M. Repression of Stress-Induced LINE-1 Expression Protects Cancer Cell Subpopulations from Lethal Drug Exposure. Cancer Cell 2017; 32:221-237.e13. [PMID: 28781121 DOI: 10.1016/j.ccell.2017.07.002] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 05/02/2017] [Accepted: 07/05/2017] [Indexed: 12/30/2022]
Abstract
Maintenance of phenotypic heterogeneity within cell populations is an evolutionarily conserved mechanism that underlies population survival upon stressful exposures. We show that the genomes of a cancer cell subpopulation that survives treatment with otherwise lethal drugs, the drug-tolerant persisters (DTPs), exhibit a repressed chromatin state characterized by increased methylation of histone H3 lysines 9 and 27 (H3K9 and H3K27). We also show that survival of DTPs is, in part, maintained by regulators of H3K9me3-mediated heterochromatin formation and that the observed increase in H3K9me3 in DTPs is most prominent over long interspersed repeat element 1 (LINE-1). Disruption of the repressive chromatin over LINE-1 elements in DTPs results in DTP ablation, which is partially rescued by reducing LINE-1 expression or function.
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Affiliation(s)
- Gulfem Dilek Guler
- Molecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | | | - Robert Pitti
- Molecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Catherine Wilson
- Molecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Katrina Nichols
- Protein Chemistry, Genentech Inc., South San Francisco, CA, USA
| | | | - Hyo-Jin Kim
- Molecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | | | - Yibing Yan
- LS Biomarker Development, Genentech Inc., South San Francisco, CA, USA
| | - Benjamin Haley
- Molecular Biology, Genentech Inc., South San Francisco, CA, USA
| | - Trinna Cuellar
- Molecular Biology, Genentech Inc., South San Francisco, CA, USA
| | | | - Navneet Alag
- Molecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Ganapati Hegde
- Molecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Erica Jackson
- Molecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | | | | | | | - Jinfeng Liu
- Bioinformatics, Genentech Inc., South San Francisco, CA, USA
| | | | - Jeff Settleman
- Molecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | | | - David Arnott
- Protein Chemistry, Genentech Inc., South San Francisco, CA, USA
| | - Marie Classon
- Molecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
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Liu T, Li W, Lu W, Chen M, Luo M, Zhang C, Li Y, Qin G, Shi D, Xiao B, Qiu H, Yu W, Kang L, Kang T, Huang W, Yu X, Wu X, Deng W. RBFOX3 Promotes Tumor Growth and Progression via hTERT Signaling and Predicts a Poor Prognosis in Hepatocellular Carcinoma. Am J Cancer Res 2017; 7:3138-3154. [PMID: 28839469 PMCID: PMC5566111 DOI: 10.7150/thno.19506] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 05/19/2017] [Indexed: 12/18/2022] Open
Abstract
Activation of the telomere maintenance mechanism is a key hallmark of cancer. Human telomerase reverse transcriptase (hTERT) is the catalytic subunit of telomerase, which is highly expressed in more than 80% of tumors, including hepatocellular carcinoma (HCC). However, the exact mechanisms by which hTERT is up-regulated in HCCs and promotes tumor growth and progression is not fully understood. The aim of this study was to discover the novel molecular targets that modulate hTERT signaling and HCC growth. In this study, we pulled down and identified RBFOX3 (RNA binding protein fox-1 homolog 3) as a novel hTERT promoter-binding protein in HCC cells using biotin-streptavidin-agarose pull-down and proteomics approach, and validated it as a regulatory factor for hTERT signaling and tumor growth in HCCs. Knockdown of RBFOX3 suppressed the promoter activity and expression of hTERT and consequently inhibited the growth and progression of HCC cells in vitro and in vivo. The suppression of HCC growth mediated by RBFOX3 knockdown could be rescued by hTERT overexpression. Conversely, exogenous overexpression of RBFOX3 activated the promoter activity and expression of hTERT and promoted the growth and progression of HCC cells. Moreover, we found that RBFOX3 interacted with AP-2β to regulate the expression of hTERT. Furthermore, we demonstrated that RBFOX3 expression was higher in the tumor tissues of HCC patients compared to the corresponding paracancer tissues, and was positively correlated with hTERT expression. Kaplan-Meier analysis showed that the HCC patients with high levels of RBFOX3 and hTERT had poor prognosis. Collectively, our data indicate that RBFOX3 promotes HCC growth and progression and predicts a poor prognosis by activating the hTERT signaling, and suggest that the RBFOX3/hTERT pathway may be a potential therapeutic target for HCC patients.
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30
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Naderlinger E, Holzmann K. Epigenetic Regulation of Telomere Maintenance for Therapeutic Interventions in Gliomas. Genes (Basel) 2017; 8:E145. [PMID: 28513547 DOI: 10.3390/genes8050145] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/08/2017] [Accepted: 05/12/2017] [Indexed: 02/07/2023] Open
Abstract
High-grade astrocytoma of WHO grade 4 termed glioblastoma multiforme (GBM) is a common human brain tumor with poor patient outcome. Astrocytoma demonstrates two known telomere maintenance mechanisms (TMMs) based on telomerase activity (TA) and on alternative lengthening of telomeres (ALT). ALT is associated with lower tumor grades and better outcome. In contrast to ALT, regulation of TA in tumors by direct mutation and epigenetic activation of the hTERT promoter is well established. Here, we summarize the genetic background of TMMs in non-malignant cells and in cancer, in addition to clinical and pathological features of gliomas. Furthermore, we present new evidence for epigenetic mechanisms (EMs) involved in regulation of ALT and TA with special emphasis on human diffuse gliomas as potential therapeutic drug targets. We discuss the role of TMM associated telomeric chromatin factors such as DNA and histone modifying enzymes and non-coding RNAs including microRNAs and long telomeric TERRA transcripts.
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31
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Olovnikov IA, Morgunova VV, Mironova AA, Kordyukova MY, Radion EI, Olenkina OM, Akulenko NV, Kalmykova AI. Interaction of Telomeric Retroelement HeT-A Transcripts and Their Protein Product Gag in Early Embryogenesis of Drosophila. Biochemistry (Mosc) 2017; 81:1023-30. [PMID: 27682174 DOI: 10.1134/s000629791609011x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The telomere is a nucleoprotein complex at the ends of linear chromosomes that protects them from fusion and degradation. The telomere consists of telomeric DNA, a protective protein complex and telomeric RNA. Biogenesis of telomeric transcripts in development is still far from being understood. Drosophila telomeres are elongated by a transposition of specialized telomeric retrotransposons that encode proteins. Using transgenic constructs encoding tagged telomeric protein, we found that transcripts of Drosophila telomeric element HeT-A bind Gag-HeT-A protein encoded by these transcripts. Maternal HeT-A transcripts and Gag-HeT-A form ribonucleoprotein granules around centrosomes, centers of microtubule organization, during blastoderm formation, upon disruption of telomere silencing during oogenesis. The specific localization of HeT-A RNA is dependent on microtubules since disruption of microtubules caused delocalization of HeT-A transcripts. This transgenic system is a valuable model for the study of telomeric RNA biogenesis.
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Affiliation(s)
- I A Olovnikov
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, 123182, Russia.
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32
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Shukla R. Retrotransposons and genetic instability in hepatocellular carcinoma. Hepat Oncol 2017; 4:5-8. [PMID: 30191048 DOI: 10.2217/hep-2017-0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 06/06/2017] [Indexed: 11/21/2022] Open
Affiliation(s)
- Ruchi Shukla
- Northern Institute for Cancer Research, Newcastle University, NE2 4HH, UK
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Chang HB, Zou JZ, He C, Zeng R, Li YY, Ma FF, Liu Z, Ye H, Wu JX. Association between Long Interspersed Nuclear Element-1 Methylation and Relative Telomere Length in Wilms Tumor. Chin Med J (Engl) 2016; 128:3055-61. [PMID: 26608986 PMCID: PMC4795265 DOI: 10.4103/0366-6999.169071] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Background: DNA hypomethylation of long interspersed nuclear elements-1 (LINEs-1) occurs during carcinogenesis, whereas information addressing LINE-1 methylation in Wilms tumor (WT) is limited. The main purpose of our study was to quantify LINE-1 methylation levels and evaluate their relationship with relative telomere length (TL) in WT. Methods: We investigated LINE-1 methylation and relative TL using bisulfite-polymerase chain reaction (PCR) pyrosequencing and quantitative PCR, respectively, in 20 WT tissues, 10 normal kidney tissues and a WT cell line. Significant changes were analyzed by t-tests. Results: LINE-1 methylation levels were significantly lower (P < 0.05) and relative TLs were significantly shorter (P < 0.05) in WT compared with normal kidney. There was a significant positive relationship between LINE-1 methylation and relative TL in WT (r = 0.671, P = 0.001). LINE-1 Methylation levels were significantly associated with global DNA methylation (r = 0.332, P < 0.01). In addition, relative TL was shortened and LINE-1 methylation was decreased in a WT cell line treated with the hypomethylating agent 5-aza-2′-deoxycytidine compared with untreated WT cell line. Conclusion: These results suggest that LINE-1 hypomethylation is common and may be linked to telomere shortening in WT.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Jian-Xin Wu
- Department of Biochemistry, Capital Institute of Pediatrics, Beijing 100020, China
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35
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Druliner BR, Ruan X, Johnson R, Grill D, O'Brien D, Lai TP, Rashtak S, Felmlee-Devine D, Washechek-Aletto J, Malykh A, Smyrk T, Oberg A, Liu H, Shay JW, Ahlquist DA, Boardman LA. Time Lapse to Colorectal Cancer: Telomere Dynamics Define the Malignant Potential of Polyps. Clin Transl Gastroenterol 2016; 7:e188. [PMID: 27584834 PMCID: PMC5288594 DOI: 10.1038/ctg.2016.48] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 07/26/2016] [Indexed: 02/07/2023] Open
Abstract
Objective: Whereas few adenomas become cancer, most colorectal cancers arise from adenomas. Telomere length is a recognized biomarker in multiple cancers, and telomere maintenance mechanisms (TMM) are exploited by malignant cells. We sought to determine whether telomere length and TMM distinguish cancer-associated adenomas from those that are cancer-free. Methods: Tissues were identified as cancer-adjacent polyp (CAP)—residual adenoma contiguous with cancer—and cancer-free polyp (CFP)—adenomas without malignancy. Telomere length, TMM, and expression were measured in 102 tissues including peripheral blood leukocytes (PBLs), normal colon epithelium, adenoma, and cancer (in CAP cases) from 31 patients. Telomere length was measured in a separate cohort of 342 PBL from CAP and CFP patients. Results: The mean differences in telomere length between normal and adenoma were greater in CAP than in CFP cases, P=0.001; telomere length in PBL was 91.7 bp greater in CAP than in CFP, P=0.007. Each 100 bp telomere increase was associated with a 1.14 (1.04–1.26) increased odds of being a CAP, P=0.0063. The polyp tissue from CAP patients had shorter telomeres and higher Telomerase reverse transcriptase (hTERT) expression compared with polyps from CFP patients, P=0.05. There was a greater degree of alternative lengthening of telomere (ALT) level difference in CFP polyps than in CAP polyps. The polyp telomere lengths of aggressive CAPs were significantly different from the polyps of non-aggressive CAPs, P=0.01. Conclusions: Adenomas that progress to cancer exhibit distinct telomere length and TMM profiles. We report for the first time that PBL telomeres differ in patients with polyps that become malignant, and therefore may have clinical value in adenoma risk assessment and management.
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Affiliation(s)
- Brooke R Druliner
- Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Xiaoyang Ruan
- Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, USA
| | - Ruth Johnson
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Diane Grill
- Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, USA
| | - Daniel O'Brien
- Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, USA
| | - Tsung-Po Lai
- Department of Cell Biology UT Southwestern Medical Center, Dallas, Texas, USA
| | - Shahrooz Rashtak
- Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Donna Felmlee-Devine
- Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Jill Washechek-Aletto
- Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Andrei Malykh
- Capital Biosciences Inc., Gaithersburg, Maryland, USA
| | - Thomas Smyrk
- Anatomic Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Ann Oberg
- Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, USA
| | - Hongfang Liu
- Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, USA
| | - Jerry W Shay
- Department of Cell Biology UT Southwestern Medical Center, Dallas, Texas, USA
| | - David A Ahlquist
- Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Lisa A Boardman
- Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
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Kreilmeier T, Mejri D, Hauck M, Kleiter M, Holzmann K. Telomere Transcripts Target Telomerase in Human Cancer Cells. Genes (Basel) 2016; 7:E46. [PMID: 27537914 DOI: 10.3390/genes7080046] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 07/24/2016] [Accepted: 07/29/2016] [Indexed: 12/14/2022] Open
Abstract
Long non-coding transcripts from telomeres, called telomeric repeat-containing RNA (TERRA), were identified as blocking telomerase activity (TA), a telomere maintenance mechanism (TMM), in tumors. We expressed recombinant TERRA transcripts in tumor cell lines with TA and with alternative lengthening of telomeres (ALT) to study effects on TMM and cell growth. Adeno- and lentivirus constructs (AV and LV) were established for transient and stable expression of approximately 130 units of telomere hexanucleotide repeats under control of cytomegalovirus (CMV) and human RNase P RNA H1 (hH1) promoters with and without polyadenylation, respectively. Six human tumor cell lines either using telomerase or ALT were infected and analyzed for TA levels. Pre-infection cells using telomerase had 1%-3% of the TERRA expression levels of ALT cells. AV and LV expression of recombinant TERRA in telomerase positive cells showed a 1.3-2.6 fold increase in TERRA levels, and a decrease in TA of 25%-58%. Dominant-negative or small hairpin RNA (shRNA) viral expression against human telomerase reverse transcriptase (hTERT) results in senescence, not induced by TERRA expression. Population doubling time, cell viability and TL (telomere length) were not impacted by ectopic TERRA expression. Clonal growth was reduced by TERRA expression in TA but not ALT cell lines. ALT cells were not affected by treatments applied. Established cell models and tools may be used to better understand the role of TERRA in the cell, especially for targeting telomerase.
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Abstract
Long interspersed element type 1 (LINE-1, L1) is a mobile genetic element comprising about 17% of the human genome, encoding a newly identified ORF0 with unknown function, ORF1p with RNA-binding activity and ORF2p with endonuclease and reverse transcriptase activities required for L1 retrotransposition. L1 utilizes an endonuclease (EN) to insert L1 cDNA into target DNA, which induces DNA double-strand breaks (DSBs). The ataxia-telangiectasia mutated (ATM) is activated by DSBs and subsequently the ATM-signaling pathway plays a role in regulating L1 retrotransposition. In addition, the host DNA repair machinery such as non-homologous end-joining (NHEJ) repair pathway is also involved in L1 retrotransposition. On the other hand, L1 is an insertional mutagenic agent, which contributes to genetic change, genomic instability, and tumorigenesis. Indeed, high-throughput sequencing-based approaches identified numerous tumor-specific somatic L1 insertions in variety of cancers, such as colon cancer, breast cancer, and hepatocellular carcinoma (HCC). In fact, L1 retrotransposition seems to be a potential factor to reduce the tumor suppressive property in HCC. Furthermore, recent study demonstrated that a specific viral-human chimeric transcript, HBx-L1, contributes to hepatitis B virus (HBV)-associated HCC. In contrast, host cells have evolved several defense mechanisms protecting cells against retrotransposition including epigenetic regulation through DNA methylation and host defense factors, such as APOBEC3, MOV10, and SAMHD1, which restrict L1 mobility as a guardian of the human genome. In this review, I focus on somatic L1 insertions into the human genome in cancers and host defense mechanisms against deleterious L1 insertions.
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Affiliation(s)
- Yasuo Ariumi
- Ariumi Project Laboratory, Center for AIDS Research and International Research Center for Medical Sciences, Kumamoto University Kumamoto, Japan
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38
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Hall LL, Lawrence JB. RNA as a fundamental component of interphase chromosomes: could repeats prove key? Curr Opin Genet Dev 2016; 37:137-147. [PMID: 27218204 DOI: 10.1016/j.gde.2016.04.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 04/01/2016] [Accepted: 04/06/2016] [Indexed: 11/29/2022]
Abstract
Beginning with the precedent of XIST RNA as a 'chromosomal RNA' (cRNA), there is growing interest in the possibility that a diversity of non-coding RNAs may function in chromatin. We review findings which lead us to suggest that RNA is essentially a widespread component of interphase chromosomes. Further, RNA likely contributes to architecture and regulation, with repeat-rich 'junk' RNA in euchromatin (ecRNA) promoting a more open chromatin state. Thousands of low-abundance nuclear RNAs have been reported, however it remains a challenge to determine which of these may function in chromatin. Recent findings indicate that repetitive sequences are enriched in chromosome-associated non-coding RNAs, and repeat-rich RNA shows unusual properties, including localization and stability, with similarities to XIST RNA. We suggest two frontiers in genome biology are emerging and may intersect: the broad contribution of RNA to interphase chromosomes and the distinctive properties of repeat-rich intronic or intergenic junk sequences that may play a role in chromosome structure and regulation.
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Affiliation(s)
- Lisa L Hall
- Department of Cell & Developmental Biology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Jeanne B Lawrence
- Department of Cell & Developmental Biology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
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Sciamanna I, De Luca C, Spadafora C. The Reverse Transcriptase Encoded by LINE-1 Retrotransposons in the Genesis, Progression, and Therapy of Cancer. Front Chem 2016; 4:6. [PMID: 26904537 PMCID: PMC4749692 DOI: 10.3389/fchem.2016.00006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 01/26/2016] [Indexed: 12/24/2022] Open
Abstract
In higher eukaryotic genomes, Long Interspersed Nuclear Element 1 (LINE-1) retrotransposons represent a large family of repeated genomic elements. They transpose using a reverse transcriptase (RT), which they encode as part of the ORF2p product. RT inhibition in cancer cells, either via RNA interference-dependent silencing of active LINE-1 elements, or using RT inhibitory drugs, reduces cancer cell proliferation, promotes their differentiation and antagonizes tumor progression in animal models. Indeed, the non-nucleoside RT inhibitor efavirenz has recently been tested in a phase II clinical trial with metastatic prostate cancer patients. An in-depth analysis of ORF2p in a mouse model of breast cancer showed ORF2p to be precociously expressed in precancerous lesions and highly abundant in advanced cancer stages, while being barely detectable in normal breast tissue, providing a rationale for the finding that RT-expressing tumors are therapeutically sensitive to RT inhibitors. We summarize mechanistic and gene profiling studies indicating that abundant LINE-1-derived RT can “sequester” RNA substrates for reverse transcription in tumor cells, entailing the formation of RNA:DNA hybrid molecules and impairing the overall production of regulatory miRNAs, with a global impact on the cell transcriptome. Based on these data, LINE-1-ORF2 encoded RT has a tumor-promoting potential that is exerted at an epigenetic level. We propose a model whereby LINE1-RT drives a previously unrecognized global regulatory process, the deregulation of which drives cell transformation and tumorigenesis with possible implications for cancer cell heterogeneity.
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Affiliation(s)
| | | | - Corrado Spadafora
- Institute of Translational Pharmacology, National Resarch Council of Italy Rome, Italy
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Aschacher T, Enzmann F. Detection of Anaphase Bridge Formation by Immunofluorescence Microscopy in Mammalian Cells. Bio Protoc 2016. [DOI: 10.21769/bioprotoc.1977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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41
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Abstract
Retrotransposons are repetitive DNA sequences that are positioned throughout the human genome. Retrotransposons are capable of copying themselves and mobilizing new copies to novel genomic locations in a process called retrotransposition. While most retrotransposon sequences in the human genome are incomplete and incapable of mobilization, the LINE-1 retrotransposon, which comprises~17% of the human genome, remains active. The disruption of cellular mechanisms that suppress retrotransposon activity is linked to the generation of aneuploidy, a potential driver of tumor development. When retrotransposons insert into a novel genomic region, they have the potential to disrupt the coding sequence of endogenous genes and alter gene expression, which can lead to deleterious consequences for the organism. Additionally, increased LINE-1 copy numbers provide more chances for recombination events to occur between retrotransposons, which can lead to chromosomal breaks and rearrangements. LINE-1 activity is increased in various cancer cell lines and in patient tissues resected from primary tumors. LINE-1 activity also correlates with increased cancer metastasis. This review aims to give a brief overview of the connections between LINE-1 retrotransposition and the loss of genome stability. We will also discuss the mechanisms that repress retrotransposition in human cells and their links to cancer.
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Affiliation(s)
- Jacqueline R Kemp
- Department of Cellular and Molecular Medicine, Lerner Research Institute of Cleveland Clinic Cleveland, OH, USA
| | - Michelle S Longworth
- Department of Cellular and Molecular Medicine, Lerner Research Institute of Cleveland Clinic Cleveland, OH, USA
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