1
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Wang ZY, Ge LP, Ouyang Y, Jin X, Jiang YZ. Targeting transposable elements in cancer: developments and opportunities. Biochim Biophys Acta Rev Cancer 2024; 1879:189143. [PMID: 38936517 DOI: 10.1016/j.bbcan.2024.189143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 05/23/2024] [Accepted: 06/19/2024] [Indexed: 06/29/2024]
Abstract
Transposable elements (TEs), comprising nearly 50% of the human genome, have transitioned from being perceived as "genomic junk" to key players in cancer progression. Contemporary research links TE regulatory disruptions with cancer development, underscoring their therapeutic potential. Advances in long-read sequencing, computational analytics, single-cell sequencing, proteomics, and CRISPR-Cas9 technologies have enriched our understanding of TEs' clinical implications, notably their impact on genome architecture, gene regulation, and evolutionary processes. In cancer, TEs, including long interspersed element-1 (LINE-1), Alus, and long terminal repeat (LTR) elements, demonstrate altered patterns, influencing both tumorigenic and tumor-suppressive mechanisms. TE-derived nucleic acids and tumor antigens play critical roles in tumor immunity, bridging innate and adaptive responses. Given their central role in oncology, TE-targeted therapies, particularly through reverse transcriptase inhibitors and epigenetic modulators, represent a novel avenue in cancer treatment. Combining these TE-focused strategies with existing chemotherapy or immunotherapy regimens could enhance efficacy and offer a new dimension in cancer treatment. This review delves into recent TE detection advancements, explores their multifaceted roles in tumorigenesis and immune regulation, discusses emerging diagnostic and therapeutic approaches centered on TEs, and anticipates future directions in cancer research.
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Affiliation(s)
- Zi-Yu Wang
- Department of Breast Surgery, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Li-Ping Ge
- Department of Breast Surgery, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Yang Ouyang
- Department of Breast Surgery, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Xi Jin
- Department of Breast Surgery, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Yi-Zhou Jiang
- Department of Breast Surgery, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
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2
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Lee AV, Nestler KA, Chiappinelli KB. Therapeutic targeting of DNA methylation alterations in cancer. Pharmacol Ther 2024; 258:108640. [PMID: 38570075 DOI: 10.1016/j.pharmthera.2024.108640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/13/2024] [Accepted: 03/22/2024] [Indexed: 04/05/2024]
Abstract
DNA methylation is a critical component of gene regulation and plays an important role in the development of cancer. Hypermethylation of tumor suppressor genes and silencing of DNA repair pathways facilitate uncontrolled cell growth and synergize with oncogenic mutations to perpetuate cancer phenotypes. Additionally, aberrant DNA methylation hinders immune responses crucial for antitumor immunity. Thus, inhibiting dysregulated DNA methylation is a promising cancer therapy. Pharmacologic inhibition of DNA methylation reactivates silenced tumor suppressors and bolster immune responses through induction of viral mimicry. Now, with the advent of immunotherapies and discovery of the immune-modulatory effects of DNA methylation inhibitors, there is great interest in understanding how targeting DNA methylation in combination with other therapies can enhance antitumor immunity. Here, we describe the role of aberrant DNA methylation in cancer and mechanisms by which it promotes tumorigenesis and modulates immune responses. Finally, we review the initial discoveries and ongoing efforts to target DNA methylation as a cancer therapeutic.
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Affiliation(s)
- Abigail V Lee
- Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, Washington, DC, USA
| | - Kevin A Nestler
- Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, Washington, DC, USA
| | - Katherine B Chiappinelli
- Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, Washington, DC, USA.
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3
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Lanciano S, Philippe C, Sarkar A, Pratella D, Domrane C, Doucet AJ, van Essen D, Saccani S, Ferry L, Defossez PA, Cristofari G. Locus-level L1 DNA methylation profiling reveals the epigenetic and transcriptional interplay between L1s and their integration sites. CELL GENOMICS 2024; 4:100498. [PMID: 38309261 PMCID: PMC10879037 DOI: 10.1016/j.xgen.2024.100498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/20/2023] [Accepted: 01/09/2024] [Indexed: 02/05/2024]
Abstract
Long interspersed element 1 (L1) retrotransposons are implicated in human disease and evolution. Their global activity is repressed by DNA methylation, but deciphering the regulation of individual copies has been challenging. Here, we combine short- and long-read sequencing to unveil L1 methylation heterogeneity across cell types, families, and individual loci and elucidate key principles involved. We find that the youngest primate L1 families are specifically hypomethylated in pluripotent stem cells and the placenta but not in most tumors. Locally, intronic L1 methylation is intimately associated with gene transcription. Conversely, the L1 methylation state can propagate to the proximal region up to 300 bp. This phenomenon is accompanied by the binding of specific transcription factors, which drive the expression of L1 and chimeric transcripts. Finally, L1 hypomethylation alone is typically insufficient to trigger L1 expression due to redundant silencing pathways. Our results illuminate the epigenetic and transcriptional interplay between retrotransposons and their host genome.
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Affiliation(s)
- Sophie Lanciano
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Claude Philippe
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Arpita Sarkar
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - David Pratella
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Cécilia Domrane
- University Paris Cité, CNRS, Epigenetics and Cell Fate, Paris, France
| | - Aurélien J Doucet
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Dominic van Essen
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Simona Saccani
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Laure Ferry
- University Paris Cité, CNRS, Epigenetics and Cell Fate, Paris, France
| | | | - Gael Cristofari
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France.
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4
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Mendez-Dorantes C, Burns KH. LINE-1 retrotransposition and its deregulation in cancers: implications for therapeutic opportunities. Genes Dev 2023; 37:948-967. [PMID: 38092519 PMCID: PMC10760644 DOI: 10.1101/gad.351051.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Long interspersed element 1 (LINE-1) is the only protein-coding transposon that is active in humans. LINE-1 propagates in the genome using RNA intermediates via retrotransposition. This activity has resulted in LINE-1 sequences occupying approximately one-fifth of our genome. Although most copies of LINE-1 are immobile, ∼100 copies are retrotransposition-competent. Retrotransposition is normally limited via epigenetic silencing, DNA repair, and other host defense mechanisms. In contrast, LINE-1 overexpression and retrotransposition are hallmarks of cancers. Here, we review mechanisms of LINE-1 regulation and how LINE-1 may promote genetic heterogeneity in tumors. Finally, we discuss therapeutic strategies to exploit LINE-1 biology in cancers.
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Affiliation(s)
- Carlos Mendez-Dorantes
- Department of Pathology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA;
- Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142, USA
| | - Kathleen H Burns
- Department of Pathology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA;
- Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142, USA
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5
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Wang Z, Ying Y, Wang M, Chen Q, Wang Y, Yu X, He W, Li J, Zeng S, Xu C. Comprehensive identification of onco-exaptation events in bladder cancer cell lines revealed L1PA2-SYT1 as a prognosis-relevant event. iScience 2023; 26:108482. [PMID: 38058305 PMCID: PMC10696462 DOI: 10.1016/j.isci.2023.108482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 10/17/2023] [Accepted: 11/15/2023] [Indexed: 12/08/2023] Open
Abstract
Transposable elements (TEs) can provide ectopic promoters to drive the expression of oncogenes in cancer, a mechanism known as onco-exaptation. Onco-exaptation events have been extensively identified in various cancers, with bladder cancer showing a high frequency of onco-exaptation events (77%). However, the effect of most of these events in bladder cancer remains unclear. This study identified 44 onco-exaptation events in 44 bladder cancer cell lines in 137 RNA-seq datasets from six publicly available cohorts, with L1PA2 contributing the most events. L1PA2-SYT1, L1PA2-MET, and L1PA2-XCL1 had the highest frequency not only in cell lines but also in TCGA-BLCA samples. L1PA2-SYT1 showed significant tumor specificity and was found to be activated by CpG island demethylation in its promoter. The upregulation of L1PA2-SYT1 enhances the in vitro invasion of bladder cancer and is an independent risk factor for patient's overall survival, suggesting L1PA2-SYT1 being an important event that promotes the development of bladder cancer.
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Affiliation(s)
- Ziwei Wang
- Department of Urology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Yidie Ying
- Department of Urology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Maoyu Wang
- Department of Urology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Qing Chen
- Department of Urology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Yi Wang
- Department of Urology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Xufeng Yu
- Department of Urology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Wei He
- Department of Urology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Jing Li
- Department of Bioinformatics, Center for Translational Medicine, Naval Medical University, Shanghai 200433, China
- Shanghai Key Laboratory of Cell Engineering, Shanghai, China
| | - Shuxiong Zeng
- Department of Urology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Chuanliang Xu
- Department of Urology, Changhai Hospital, Naval Medical University, Shanghai 200433, China
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6
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Tam PLF, Leung D. The Molecular Impacts of Retrotransposons in Development and Diseases. Int J Mol Sci 2023; 24:16418. [PMID: 38003607 PMCID: PMC10671454 DOI: 10.3390/ijms242216418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/11/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Retrotransposons are invasive genetic elements that constitute substantial portions of mammalian genomes. They have the potential to influence nearby gene expression through their cis-regulatory sequences, reverse transcription machinery, and the ability to mold higher-order chromatin structures. Due to their multifaceted functions, it is crucial for host fitness to maintain strict regulation of these parasitic sequences to ensure proper growth and development. This review explores how subsets of retrotransposons have undergone evolutionary exaptation to enhance the complexity of mammalian genomes. It also highlights the significance of regulating these elements, drawing on recent studies conducted in human and murine systems.
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Affiliation(s)
- Phoebe Lut Fei Tam
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China;
| | - Danny Leung
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China;
- Center for Epigenomics Research, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China
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7
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Luqman-Fatah A, Miyoshi T. Human LINE-1 retrotransposons: impacts on the genome and regulation by host factors. Genes Genet Syst 2023; 98:121-154. [PMID: 36436935 DOI: 10.1266/ggs.22-00038] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Genome sequencing revealed that nearly half of the human genome is comprised of transposable elements. Although most of these elements have been rendered inactive due to mutations, full-length intact long interspersed element-1 (LINE-1 or L1) copies retain the ability to mobilize through RNA intermediates by a so-called "copy-and-paste" mechanism, termed retrotransposition. L1 is the only known autonomous mobile genetic element in the genome, and its retrotransposition contributes to inter- or intra-individual genetic variation within the human population. However, L1 retrotransposition also poses a threat to genome integrity due to gene disruption and chromosomal instability. Moreover, recent studies suggest that aberrant L1 expression can impact human health by causing diseases such as cancer and chronic inflammation that might lead to autoimmune disorders. To counteract these adverse effects, the host cells have evolved multiple layers of defense mechanisms at the epigenetic, RNA and protein levels. Intriguingly, several host factors have also been reported to facilitate L1 retrotransposition, suggesting that there is competition between negative and positive regulation of L1 by host factors. Here, we summarize the known host proteins that regulate L1 activity at different stages of the replication cycle and discuss how these factors modulate disease-associated phenotypes caused by L1.
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Affiliation(s)
- Ahmad Luqman-Fatah
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University
- Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University
| | - Tomoichiro Miyoshi
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University
- Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University
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8
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Fu J, Qin T, Li C, Zhu J, Ding Y, Zhou M, Yang Q, Liu X, Zhou J, Chen F. Research progress of LINE-1 in the diagnosis, prognosis, and treatment of gynecologic tumors. Front Oncol 2023; 13:1201568. [PMID: 37546391 PMCID: PMC10399582 DOI: 10.3389/fonc.2023.1201568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 06/19/2023] [Indexed: 08/08/2023] Open
Abstract
The retrotransposon known as long interspersed nuclear element-1 (LINE-1), which is currently the sole autonomously mobile transposon in the human genome, can result in insertional mutations, chromosomal rearrangements, and genomic instability. In recent years, numerous studies have shown that LINE-1 is involved in the development of various diseases and also plays an important role in the immune regulation of the organism. The expression of LINE-1 in gynecologic tumors suggests that it is expected to be an independent indicator for early diagnosis and prognosis, and also, as a therapeutic target, LINE-1 is closely associated with gynecologic tumor prognosis. This article discusses the function of LINE-1 in the diagnosis, treatment, and prognosis of ovarian, cervical, and endometrial malignancies, as well as other gynecologic malignancies. It offers fresh perspectives on the early detection of tumors and the creation of novel anti-tumor medications.
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Affiliation(s)
- Jiaojiao Fu
- The First Clinical Medical College of Gansu University of Chinese Medicine, Gansu Provincial Hospital, Lanzhou, China
- Department of Obstetrics and Gynecology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Tiansheng Qin
- The First Clinical Medical College of Gansu University of Chinese Medicine, Gansu Provincial Hospital, Lanzhou, China
- Department of Obstetrics and Gynecology, Gansu Provincial Hospital, Lanzhou, Gansu, China
- The First Clinical Medical School, Lanzhou University, Lanzhou, Gansu, China
- National Health Commission (NHC) Key Laboratory of Diagnosis and Therapy of Gastrointestinal Tumor, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Chaoming Li
- The First People’s Hospital of Longnan, Longnan City Hospital, Longnan, Gansu, China
| | - Jiaojiao Zhu
- The First Clinical Medical College of Gansu University of Chinese Medicine, Gansu Provincial Hospital, Lanzhou, China
- Department of Obstetrics and Gynecology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Yaoyao Ding
- The First Clinical Medical College of Gansu University of Chinese Medicine, Gansu Provincial Hospital, Lanzhou, China
- Department of Obstetrics and Gynecology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Meiying Zhou
- Department of Obstetrics and Gynecology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Qing Yang
- The First Clinical Medical College of Gansu University of Chinese Medicine, Gansu Provincial Hospital, Lanzhou, China
- Department of Obstetrics and Gynecology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Xiaofeng Liu
- The First Clinical Medical College of Gansu University of Chinese Medicine, Gansu Provincial Hospital, Lanzhou, China
- Department of Obstetrics and Gynecology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Juanhong Zhou
- The First Clinical Medical College of Gansu University of Chinese Medicine, Gansu Provincial Hospital, Lanzhou, China
- Department of Obstetrics and Gynecology, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Fan Chen
- The First Clinical Medical College of Gansu University of Chinese Medicine, Gansu Provincial Hospital, Lanzhou, China
- Department of Obstetrics and Gynecology, Gansu Provincial Hospital, Lanzhou, Gansu, China
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9
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Kim WR, Park EG, Lee YJ, Bae WH, Lee DH, Kim HS. Integration of TE Induces Cancer Specific Alternative Splicing Events. Int J Mol Sci 2022; 23:ijms231810918. [PMID: 36142830 PMCID: PMC9502224 DOI: 10.3390/ijms231810918] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/13/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
Alternative splicing of messenger RNA (mRNA) precursors contributes to genetic diversity by generating structurally and functionally distinct transcripts. In a disease state, alternative splicing promotes incidence and development of several cancer types through regulation of cancer-related biological processes. Transposable elements (TEs), having the genetic ability to jump to other regions of the genome, can bring about alternative splicing events in cancer. TEs can integrate into the genome, mostly in the intronic regions, and induce cancer-specific alternative splicing by adjusting various mechanisms, such as exonization, providing splicing donor/acceptor sites, alternative regulatory sequences or stop codons, and driving exon disruption or epigenetic regulation. Moreover, TEs can produce microRNAs (miRNAs) that control the proportion of transcripts by repressing translation or stimulating the degradation of transcripts at the post-transcriptional level. Notably, TE insertion creates a cancer-friendly environment by controlling the overall process of gene expression before and after transcription in cancer cells. This review emphasizes the correlative interaction between alternative splicing by TE integration and cancer-associated biological processes, suggesting a macroscopic mechanism controlling alternative splicing by TE insertion in cancer.
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Affiliation(s)
- Woo Ryung Kim
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Eun Gyung Park
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Yun Ju Lee
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Woo Hyeon Bae
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Du Hyeong Lee
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Heui-Soo Kim
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 46241, Korea
- Correspondence:
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10
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Bhat A, Ghatage T, Bhan S, Lahane GP, Dhar A, Kumar R, Pandita RK, Bhat KM, Ramos KS, Pandita TK. Role of Transposable Elements in Genome Stability: Implications for Health and Disease. Int J Mol Sci 2022; 23:7802. [PMID: 35887150 PMCID: PMC9319628 DOI: 10.3390/ijms23147802] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/07/2022] [Accepted: 07/12/2022] [Indexed: 12/11/2022] Open
Abstract
Most living organisms have in their genome a sizable proportion of DNA sequences capable of mobilization; these sequences are commonly referred to as transposons, transposable elements (TEs), or jumping genes. Although long thought to have no biological significance, advances in DNA sequencing and analytical technologies have enabled precise characterization of TEs and confirmed their ubiquitous presence across all forms of life. These findings have ignited intense debates over their biological significance. The available evidence now supports the notion that TEs exert major influence over many biological aspects of organismal life. Transposable elements contribute significantly to the evolution of the genome by giving rise to genetic variations in both active and passive modes. Due to their intrinsic nature of mobility within the genome, TEs primarily cause gene disruption and large-scale genomic alterations including inversions, deletions, and duplications. Besides genomic instability, growing evidence also points to many physiologically important functions of TEs, such as gene regulation through cis-acting control elements and modulation of the transcriptome through epigenetic control. In this review, we discuss the latest evidence demonstrating the impact of TEs on genome stability and the underling mechanisms, including those developed to mitigate the deleterious impact of TEs on genomic stability and human health. We have also highlighted the potential therapeutic application of TEs.
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Affiliation(s)
- Audesh Bhat
- Centre for Molecular Biology, Central University of Jammu, Jammu 181143, India;
| | - Trupti Ghatage
- Department of Pharmacy, BITS-Pilani Hyderabad Campus, Hyderabad 500078, India; (T.G.); (G.P.L.); (A.D.)
| | - Sonali Bhan
- Centre for Molecular Biology, Central University of Jammu, Jammu 181143, India;
| | - Ganesh P. Lahane
- Department of Pharmacy, BITS-Pilani Hyderabad Campus, Hyderabad 500078, India; (T.G.); (G.P.L.); (A.D.)
| | - Arti Dhar
- Department of Pharmacy, BITS-Pilani Hyderabad Campus, Hyderabad 500078, India; (T.G.); (G.P.L.); (A.D.)
| | - Rakesh Kumar
- Department of Biotechnology, Shri Mata Vaishnav Devi University, Katra 182320, India;
| | - Raj K. Pandita
- Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA;
| | - Krishna M. Bhat
- Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA;
| | - Kenneth S. Ramos
- Center for Genomics and Precision Medicine, Texas A&M College of Medicine, Houston, TX 77030, USA;
| | - Tej K. Pandita
- Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA;
- Center for Genomics and Precision Medicine, Texas A&M College of Medicine, Houston, TX 77030, USA;
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11
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Ma G, Babarinde IA, Zhou X, Hutchins AP. Transposable Elements in Pluripotent Stem Cells and Human Disease. Front Genet 2022; 13:902541. [PMID: 35719395 PMCID: PMC9201960 DOI: 10.3389/fgene.2022.902541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 05/20/2022] [Indexed: 11/18/2022] Open
Abstract
Transposable elements (TEs) are mobile genetic elements that can randomly integrate into other genomic sites. They have successfully replicated and now occupy around 40% of the total DNA sequence in humans. TEs in the genome have a complex relationship with the host cell, being both potentially deleterious and advantageous at the same time. Only a tiny minority of TEs are still capable of transposition, yet their fossilized sequence fragments are thought to be involved in various molecular processes, such as gene transcriptional activity, RNA stability and subcellular localization, and chromosomal architecture. TEs have also been implicated in biological processes, although it is often hard to reveal cause from correlation due to formidable technical issues in analyzing TEs. In this review, we compare and contrast two views of TE activity: one in the pluripotent state, where TEs are broadly beneficial, or at least mechanistically useful, and a second state in human disease, where TEs are uniformly considered harmful.
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12
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Coordination of retrotransposons and type I interferon with distinct interferon pathways in dermatomyositis, systemic lupus erythematosus and autoimmune blistering disease. Sci Rep 2021; 11:23146. [PMID: 34848794 PMCID: PMC8632942 DOI: 10.1038/s41598-021-02522-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 11/18/2021] [Indexed: 01/05/2023] Open
Abstract
Type I interferon (IFN) plays a crucial role in innate and adaptive immunity, and aberrant IFN responses are involved in systemic autoimmune diseases, such as systemic lupus erythematosus (SLE) and dermatomyositis (DM). Type I IFNs can be induced by transcribed retrotransposons. The regulation of retrotransposons and type I IFN and the downstream IFN pathways in SLE, DM, and autoimmune blistering disease (AIBD) were investigated. The gene expression levels of retrotransposons, including LINE-1, type I-III IFNs, and IFN-stimulated genes (ISGs) in peripheral blood cells from patients with DM (n = 24), SLE (n = 19), AIBD (n = 14) and healthy controls (HCs, n = 10) were assessed by quantitative polymerase chain reaction. Upregulation of retrotransposons and IFNs was detected in DM patient samples, as is characteristic, compared to HCs; however, ISGs were not uniformly upregulated. In contrast, retrotransposons and IFNs, except for type II IFN, such as IFN-γ, were not upregulated in SLE. In AIBD, only some retrotransposons and type I interferons were upregulated. The DM, SLE, and AIBD samples showed coordinated expression of retrotransposons and type I IFNs and distinct spectra of IFN signaling. A positive correlation between LINE-1 and IFN-β1 was also detected in human cell lines. These factors may participate in the development of these autoimmune diseases.
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13
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Debernardi C, Libera L, Berrino E, Sahnane N, Chiaravalli AM, Laudi C, Berselli M, Sapino A, Sessa F, Venesio T, Furlan D. Evaluation of global and intragenic hypomethylation in colorectal adenomas improves patient stratification and colorectal cancer risk prediction. Clin Epigenetics 2021; 13:154. [PMID: 34372923 PMCID: PMC8351348 DOI: 10.1186/s13148-021-01135-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/15/2021] [Indexed: 12/16/2022] Open
Abstract
Background Aberrant DNA hypomethylation of the long interspersed nuclear elements (LINE-1 or L1) has been recognized as an early event of colorectal transformation. Simultaneous genetic and epigenetic analysis of colorectal adenomas may be an effective and rapid strategy to identify key biological features leading to accelerated colorectal tumorigenesis. In particular, global and/or intragenic LINE-1 hypomethylation of adenomas may represent a helpful tool for improving colorectal cancer (CRC) risk stratification of patients after surgical removal of polyps. To verify this hypothesis, we analyzed a cohort of 102 adenomas derived from 40 high-risk patients (who developed CRC in a post-polypectomy of at least one year) and 43 low-risk patients (who did not develop CRC in a post-polypectomy of at least 5 years) for their main pathological features, the presence of hotspot variants in driver oncogenes (KRAS, NRAS, BRAF and PIK3CA), global (LINE-1) and intragenic (L1-MET) methylation status. Results In addition to a significantly higher adenoma size and an older patients’ age, adenomas from high-risk patients were more hypomethylated than those from low-risk patients for both global and intragenic LINE-1 assays. DNA hypomethylation, measured by pyrosequencing, was independent from other parameters, including the presence of oncogenic hotspot variants detected by mass spectrometry. Combining LINE-1 and L1-MET analyses and profiling the samples according to the presence of at least one hypomethylated assay improved the discrimination between high and low risk lesions (p = 0.005). Remarkably, adenomas with at least one hypomethylated assay identified the patients with a significantly (p < 0.001) higher risk of developing CRC. Multivariable analysis and logistic regression evaluated by the ROC curves proved that methylation status was an independent variable improving cancer risk prediction (p = 0.02). Conclusions LINE-1 and L1-MET hypomethylation in colorectal adenomas are associated with a higher risk of developing CRC. DNA global and intragenic hypomethylation are independent markers that could be used in combination to successfully improve the stratification of patients who enter a colonoscopy surveillance program. Graphic abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13148-021-01135-0.
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Affiliation(s)
- Carla Debernardi
- Pathology Unit, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy.,Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Laura Libera
- Pathology Unit, Department of Medicine and Surgery, University of Insubria, Varese, Italy.,Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Enrico Berrino
- Pathology Unit, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy.,Department of Medical Sciences, University of Torino, Torino, Italy.,Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Nora Sahnane
- Pathology Unit, ASST Sette Laghi, Varese, Italy.,Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Anna Maria Chiaravalli
- Pathology Unit, ASST Sette Laghi, Varese, Italy.,Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Cristiana Laudi
- Gastroenterology, Candiolo Cancer Institute, Candiolo, Italy
| | - Mattia Berselli
- Surgical Oncology and Minimally Invasive Unit, Department of Surgery, ASST Sette Laghi, Varese, Italy.,Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Anna Sapino
- Pathology Unit, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy.,Department of Medical Sciences, University of Torino, Torino, Italy
| | - Fausto Sessa
- Pathology Unit, Department of Medicine and Surgery, University of Insubria, Varese, Italy.,Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Tiziana Venesio
- Pathology Unit, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy. .,Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy.
| | - Daniela Furlan
- Pathology Unit, Department of Medicine and Surgery, University of Insubria, Varese, Italy.,Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy
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14
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Jiang JC, Rothnagel JA, Upton KR. Widespread Exaptation of L1 Transposons for Transcription Factor Binding in Breast Cancer. Int J Mol Sci 2021; 22:5625. [PMID: 34070697 PMCID: PMC8199441 DOI: 10.3390/ijms22115625] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/18/2021] [Accepted: 05/20/2021] [Indexed: 12/29/2022] Open
Abstract
L1 transposons occupy 17% of the human genome and are widely exapted for the regulation of human genes, particularly in breast cancer, where we have previously shown abundant cancer-specific transcription factor (TF) binding sites within the L1PA2 subfamily. In the current study, we performed a comprehensive analysis of TF binding activities in primate-specific L1 subfamilies and identified pervasive exaptation events amongst these evolutionarily related L1 transposons. By motif scanning, we predicted diverse and abundant TF binding potentials within the L1 transposons. We confirmed substantial TF binding activities in the L1 subfamilies using TF binding sites consolidated from an extensive collection of publicly available ChIP-seq datasets. Young L1 subfamilies (L1HS, L1PA2 and L1PA3) contributed abundant TF binding sites in MCF7 cells, primarily via their 5' UTR. This is expected as the L1 5' UTR hosts cis-regulatory elements that are crucial for L1 replication and mobilisation. Interestingly, the ancient L1 subfamilies, where 5' truncation was common, displayed comparable TF binding capacity through their 3' ends, suggesting an alternative exaptation mechanism in L1 transposons that was previously unnoticed. Overall, primate-specific L1 transposons were extensively exapted for TF binding in MCF7 breast cancer cells and are likely prominent genetic players modulating breast cancer transcriptional regulation.
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Affiliation(s)
| | | | - Kyle R. Upton
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.-C.J.); (J.A.R.)
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15
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Jiang JC, Rothnagel JA, Upton KR. Integrated transcription factor profiling with transcriptome analysis identifies L1PA2 transposons as global regulatory modulators in a breast cancer model. Sci Rep 2021; 11:8083. [PMID: 33850167 PMCID: PMC8044218 DOI: 10.1038/s41598-021-86395-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/26/2021] [Indexed: 12/13/2022] Open
Abstract
While transposons are generally silenced in somatic tissues, many transposons escape epigenetic repression in epithelial cancers, become transcriptionally active and contribute to the regulation of human gene expression. We have developed a bioinformatic pipeline for the integrated analysis of transcription factor binding and transcriptomic data to identify transposon-derived promoters that are activated in specific diseases and developmental states. We applied this pipeline to a breast cancer model, and found that the L1PA2 transposon subfamily contributes abundant regulatory sequences to co-ordinated transcriptional regulation in breast cancer. Transcription factor profiling demonstrates that over 27% of L1PA2 transposons harbour co-localised binding sites of functionally interacting, cancer-associated transcription factors in MCF7 cells, a cell line used to model breast cancer. Transcriptomic analysis reveals that L1PA2 transposons also contribute transcription start sites to up-regulated transcripts in MCF7 cells, including some transcripts with established oncogenic properties. In addition, we verified the utility of our pipeline on other transposon subfamilies, as well as on leukemia and lung carcinoma cell lines. We demonstrate that the normally quiescent regulatory activities of transposons can be activated and alter the cancer transcriptome. In particular, the L1PA2 subfamily contributes abundant regulatory sequences, and likely plays a global role in modulating breast cancer transcriptional regulation. Understanding the regulatory impact of L1PA2 on breast cancer genomes provides additional insights into cancer genome regulation, and may provide novel biomarkers for disease diagnosis, prognosis and therapy.
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Affiliation(s)
- Jiayue-Clara Jiang
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Joseph A Rothnagel
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Kyle R Upton
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia.
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16
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Rashed WM, Kandeil MA, Mahmoud MO, Maher D, Ezzat S, Abdel-Rahman MH. MET canonical transcript expression is a predictive biomarker for chemo-sensitivity to MET-inhibitors in hepatocellular carcinoma cell lines. J Cancer Res Clin Oncol 2021; 147:167-175. [PMID: 32980960 PMCID: PMC7855026 DOI: 10.1007/s00432-020-03395-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 09/16/2020] [Indexed: 12/13/2022]
Abstract
PURPOSE Long interspersed nuclear element 1 (LINE-1 or L1) is a dominant non-long terminal repeat (non-LTR) retrotransposon in the human genome that has been implicated in the overexpression of MET. Both the canonical MET and L1-MET transcripts are considered to play a role in hepatocellular carcinoma (HCC) development. The aim of this study was to assess the utility of canonical MET, L1-MET, and MET protein expressions as predictive biomarkers for chemo-sensitivity to MET-inhibitors in HCC cell lines in vitro. Additionally, we assessed their expression in tumour tissues from Egyptian HCC patients. METHODS MET and L1-MET expressions were assessed by qRT-PCR in six liver cancer cell lines (SNU-387, SNU-475, SK-HEP-1, PLC/PRF/5, SNU-449 and SNU-423) and 47 HCC tumour tissues. MET protein expression was measured by western blot in cell lines and immunohistochemistry in the tumours. Cell proliferation assay was used to assess the effect of crizotinib and tivantinib on the six liver cancer cell lines in correlation with the expression of MET, L1-MET and MET. RESULTS The antitumor effect of crizotinib and tivantinib correlated with MET gene expression but not with L1-MET transcript or MET protein expressions. No significant difference was observed between HCC tumours and non-tumour samples in MET and L1-MET transcripts expression. There were no significant correlations between the 2-year overall survival rate and the MET, L1-MET transcripts and the MET protein expression. CONCLUSION MET RNA expression could be useful biomarker for tivantinib and crizotinib targeted therapy in HCC. The value of assessment of MET protein expression is limited.
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Affiliation(s)
- Wafaa M Rashed
- Department of Research, Children's Cancer Hospital, Egypt, Cairo, Egypt
| | - Mohamed A Kandeil
- Department of Biochemistry, Faculty of Veterinary Medicine, Beni-Suef University, Beni Suef, Egypt
| | - Mohamed O Mahmoud
- Department of Biochemistry, Faculty of Pharmacy, Beni-Suef University, Beni Suef, Egypt
| | - Doha Maher
- Department of Pathology, National Liver Institute, Menoufia University, Menoufia, Egypt
| | - Sameera Ezzat
- Department of Epidemiology and Prevention Medicine, National Liver Institute, Menoufia University, Menoufia, Egypt
| | - Mohamed H Abdel-Rahman
- Department of Pathology, National Liver Institute, Menoufia University, Menoufia, Egypt.
- Division of Human Genetics, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA.
- Department of Ophthalmology, The Ohio State University, 400 W 12th Ave, Room 202 Wiseman Hall, Columbus, OH, 43210, USA.
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17
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Impact of Tumor LINE-1 Methylation Level and Neoadjuvant Treatment and Its Association with Colorectal Cancer Survival. J Pers Med 2020; 10:jpm10040219. [PMID: 33187096 PMCID: PMC7712476 DOI: 10.3390/jpm10040219] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 10/26/2020] [Accepted: 11/09/2020] [Indexed: 12/12/2022] Open
Abstract
Recent studies suggest that long-interspersed nucleotide element-1 (LINE-1) hypomethylation is commonly found in colorectal cancer (CRC), and is associated with worse prognosis. However, the utility of LINE-1 methylation on the prognosis of CRC is still controversial, and may be due to the fact that some clinical and pathological features may affect LINE-1 methylation. Thus, the aim of this study was to assess the prognostic value of tumor LINE-1 methylation in CRC, through their association with the CRC clinical and pathological characteristics. Survival of sixty-seven CRC patients was evaluated according to the median of tumor LINE-1 methylation, as well as pathological and oncological variables. We also studied the association between LINE-1 methylation and pathological features, and finally, we assessed the overall and disease-free survival of LINE1 methylation, stratified by neoadjuvant treatment and further checked by multivariate Cox regression to assess the statistical interactions. LINE-1 was hypomethylated in the CRC tumor with respect to the tumor adjacent-free area (p < 0.05), without association with any other clinical and oncological features, nor with overall and disease-free survival rates for CRC. Relevantly, in neoadjuvant treatment, LINE-1 methylation was associated with survival rates. Thus, disease-free and overall survival rates of treated CRC patients were worse in the hypomethylated LINE-1 tumors than those with normal LINE-1 methylation (p = 0.004 and 0.0049, respectively). Indeed, LINE-1 was hypermethylated more in the treated patients than in the non-treated patients (p < 0.05). The present study showed that tumor LINE-1 hypomethylation was associated with worse survival rates in only treated patients. Our data suggest an interactive effect of neoadjuvant treatment and tumor LINE-1 methylation, which could be a specific-tissue biomarker to predict survival of the treated patients, and help to personalize treatment in CRC.
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18
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Aberrant Methylation of LINE-1 Transposable Elements: A Search for Cancer Biomarkers. Cells 2020; 9:cells9092017. [PMID: 32887319 PMCID: PMC7563416 DOI: 10.3390/cells9092017] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/26/2020] [Accepted: 08/31/2020] [Indexed: 02/07/2023] Open
Abstract
Cancer remains one of the main causes of human mortality despite significant progress in its diagnostics and therapy achieved in the past decade. Massive hypomethylation of retrotransposons, in particular LINE-1, is considered a hallmark of most malignant transformations as it results in the reactivation of retroelements and subsequent genomic instability. Accumulating data on LINE-1 aberrant methylation in different tumor types indicates its significant role in cancer initiation and progression. However, direct evidence that LINE-1 activation can be used as a cancer biomarker is still limited. The objective of this review was to critically evaluate the published results regarding the diagnostic/prognostic potential of the LINE-1 methylation status in cancer. Our analysis indicates that LINE-1 hypomethylation is a promising candidate biomarker of cancer development, which, however, needs validation in both clinical and laboratory studies to confirm its applicability to different cancer types and/or stages. As LINE-1 is present in multiple cell-free copies in blood, it has advantages over single-copy genes regarding perspectives of using its methylation status as an epigenetic cancer biomarker for cell-free DNA liquid biopsy.
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19
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Zhang X, Zhang R, Yu J. New Understanding of the Relevant Role of LINE-1 Retrotransposition in Human Disease and Immune Modulation. Front Cell Dev Biol 2020; 8:657. [PMID: 32850797 PMCID: PMC7426637 DOI: 10.3389/fcell.2020.00657] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/01/2020] [Indexed: 12/21/2022] Open
Abstract
Long interspersed nuclear element-1 (LINE-1) retrotransposition is a major hallmark of cancer accompanied by global chromosomal instability, genomic instability, and genetic heterogeneity and has become one indicator for the occurrence, development, and poor prognosis of many diseases. LINE-1 also modulates the immune system and affects the immune microenvironment in a variety of ways. Aberrant expression of LINE-1 retrotransposon can provide strong stimuli for an innate immune response, activate the immune system, and induce autoimmunity and inflammation. Therefore, inhibition the activity of LINE-1 has become a potential treatment strategy for various diseases. In this review, we discussed the components and regulatory mechanisms involved with LINE-1, its correlations with disease and immunity, and multiple inhibitors of LINE-1, providing a new understanding of LINE-1.
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Affiliation(s)
- Xiao Zhang
- Cancer Molecular Diagnostics Core, Tianjin Medical University Cancer Institute & Hospital, National Clinical Research Center of Caner, Key Laboratory of Cancer Prevention and Therapy, Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China.,Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Rui Zhang
- Cancer Molecular Diagnostics Core, Tianjin Medical University Cancer Institute & Hospital, National Clinical Research Center of Caner, Key Laboratory of Cancer Prevention and Therapy, Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China.,Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Jinpu Yu
- Cancer Molecular Diagnostics Core, Tianjin Medical University Cancer Institute & Hospital, National Clinical Research Center of Caner, Key Laboratory of Cancer Prevention and Therapy, Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China.,Tianjin's Clinical Research Center for Cancer, Tianjin, China
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20
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Zeggar HR, How-Kit A, Daunay A, Bettaieb I, Sahbatou M, Rahal K, Adouni O, Gammoudi A, Douik H, Deleuze JF, Kharrat M. Tumor DNA hypomethylation of LINE-1 is associated with low tumor grade of breast cancer in Tunisian patients. Oncol Lett 2020; 20:1999-2006. [PMID: 32724446 PMCID: PMC7377197 DOI: 10.3892/ol.2020.11745] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 05/19/2020] [Indexed: 12/24/2022] Open
Abstract
DNA hypomethylation of long interspersed repetitive DNA retrotransposon (LINE-1) and Alu repeats elements of short interspersed elements family (SINEs) is an early event in carcinogenesis that causes transcriptional activation and leads to chromosomal instability. In the current study, DNA methylation levels of LINE-1 and Alu repeats were analyzed in tumoral tissues of invasive breast cancer in a Tunisian cohort and its association with the clinicopathological features of patients was defined. DNA methylation of LINE-1 and Alu repeats were analyzed using pyrosequencing in 61 invasive breast cancers. Median values observed for DNA methylation of LINE-1 and Alu repeats were considered as the cut-off (59.81 and 18.49%, respectively). The results of the current study demonstrated a positive correlation between DNA methylation levels of LINE-1 and Alu repeats (rho=0.284; P<0.03). DNA hypomethylation of LINE-1 was also indicated to be associated with low grade (P=0.023). To the best of our knowledge, the current study is the first study regarding DNA methylation of LINE-1 and Alu repeats element in breast cancer of the Tunisian population. The results of the current study suggest that, since hypomethylation of LINE-1 is associated with low grade, it could be used as a biomarker for prognosis for patients with breast cancer.
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Affiliation(s)
- Hayet Radia Zeggar
- University of Tunis El Manar, Faculty of Medicine of Tunis, LR99ES10 Human Genetics Laboratory, 1007 Tunis, Tunisia
| | - Alexandre How-Kit
- Laboratoire de Génomique, Fondation Jean Dausset-CEPH, Centre d'Etude du Polymorphisme Humain, 75010 Paris, France
| | - Antoine Daunay
- Laboratoire de Génomique, Fondation Jean Dausset-CEPH, Centre d'Etude du Polymorphisme Humain, 75010 Paris, France
| | - Ilhem Bettaieb
- Department of Immunohistocytology, Salah Azaïz Cancer Institute, 1006 Tunis, Tunisia
| | - Mourad Sahbatou
- Laboratoire de Biostatistique, Fondation Jean Dausset-CEPH, Centre d'Etude du Polymorphisme Humain, 75010 Paris, France
| | - Khaled Rahal
- Service de Chirurgie Carcinologique, Institut Salah Azaiz de Tunis, 1006 Tunis, Tunisia
| | - Olfa Adouni
- Department of Immunohistocytology, Salah Azaïz Cancer Institute, 1006 Tunis, Tunisia
| | - Amor Gammoudi
- Department of Immunohistocytology, Salah Azaïz Cancer Institute, 1006 Tunis, Tunisia
| | - Hayet Douik
- University of Tunis El Manar, Faculty of Medicine of Tunis, LR99ES10 Human Genetics Laboratory, 1007 Tunis, Tunisia
| | - Jean-François Deleuze
- Laboratoire de Génomique, Fondation Jean Dausset-CEPH, Centre d'Etude du Polymorphisme Humain, 75010 Paris, France
- Centre National de Recherche en Génomique Humaine, CEA, Le Commissariat à l'énergie atomique et aux énergies alternatives-Institut François Jacob, 92265 Evry, France
| | - Maher Kharrat
- University of Tunis El Manar, Faculty of Medicine of Tunis, LR99ES10 Human Genetics Laboratory, 1007 Tunis, Tunisia
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Lanciano S, Cristofari G. Measuring and interpreting transposable element expression. Nat Rev Genet 2020; 21:721-736. [PMID: 32576954 DOI: 10.1038/s41576-020-0251-y] [Citation(s) in RCA: 166] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2020] [Indexed: 12/21/2022]
Abstract
Transposable elements (TEs) are insertional mutagens that contribute greatly to the plasticity of eukaryotic genomes, influencing the evolution and adaptation of species as well as physiology or disease in individuals. Measuring TE expression helps to understand not only when and where TE mobilization can occur but also how this process alters gene expression, chromatin accessibility or cellular signalling pathways. Although genome-wide gene expression assays such as RNA sequencing include transposon-derived transcripts, most computational analytical tools discard or misinterpret TE-derived reads. Emerging approaches are improving the identification of expressed TE loci and helping to discriminate TE transcripts that permit TE mobilization from chimeric gene-TE transcripts or pervasive transcription. Here we review the main challenges associated with the detection of TE expression, including mappability, insertional and internal sequence polymorphisms, and the diversity of the TE transcriptional landscape, as well as the different experimental and computational strategies to solve them.
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22
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Corre I, Verrecchia F, Crenn V, Redini F, Trichet V. The Osteosarcoma Microenvironment: A Complex But Targetable Ecosystem. Cells 2020; 9:cells9040976. [PMID: 32326444 PMCID: PMC7226971 DOI: 10.3390/cells9040976] [Citation(s) in RCA: 243] [Impact Index Per Article: 60.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/06/2020] [Accepted: 04/11/2020] [Indexed: 01/08/2023] Open
Abstract
Osteosarcomas are the most frequent primary bone sarcomas, affecting mainly children, adolescents, and young adults, and with a second peak of incidence in elderly individuals. The current therapeutic management, a combined regimen of poly-chemotherapy and surgery, still remains largely insufficient, as patient survival has not improved in recent decades. Osteosarcomas are very heterogeneous tumors, both at the intra- and inter-tumor level, with no identified driver mutation. Consequently, efforts to improve treatments using targeted therapies have faced this lack of specific osteosarcoma targets. Nevertheless, these tumors are inextricably linked to their local microenvironment, composed of bone, stromal, vascular and immune cells and the osteosarcoma microenvironment is now considered to be essential and supportive for growth and dissemination. This review describes the different actors of the osteosarcoma microenvironment and gives an overview of the past, current, and future strategies of therapy targeting this complex ecosystem, with a focus on the role of extracellular vesicles and on the emergence of multi-kinase inhibitors.
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Affiliation(s)
- Isabelle Corre
- INSERM, Nantes University, UMR1238 Phy-Os “Bone Sarcomas and Remodeling of Calcified Tissues”, F-44035 Nantes, France
- CNRS GDR3697 MicroNit, F-37044 Tours, France
- Correspondence: (I.C.); (V.T.)
| | - Franck Verrecchia
- INSERM, Nantes University, UMR1238 Phy-Os “Bone Sarcomas and Remodeling of Calcified Tissues”, F-44035 Nantes, France
| | - Vincent Crenn
- INSERM, Nantes University, UMR1238 Phy-Os “Bone Sarcomas and Remodeling of Calcified Tissues”, F-44035 Nantes, France
- Department of Orthopedic, Nantes Hospital, CHU Hotel-Dieu, F-44035 Nantes, France
| | - Francoise Redini
- INSERM, Nantes University, UMR1238 Phy-Os “Bone Sarcomas and Remodeling of Calcified Tissues”, F-44035 Nantes, France
| | - Valérie Trichet
- INSERM, Nantes University, UMR1238 Phy-Os “Bone Sarcomas and Remodeling of Calcified Tissues”, F-44035 Nantes, France
- CNRS GDR3697 MicroNit, F-37044 Tours, France
- Correspondence: (I.C.); (V.T.)
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Cervantes-Ayalc A, Ruiz Esparza-Garrido R, Velázquez-Flores MÁ. Long Interspersed Nuclear Elements 1 (LINE1): The chimeric transcript L1-MET and its involvement in cancer. Cancer Genet 2020; 241:1-11. [PMID: 31918342 DOI: 10.1016/j.cancergen.2019.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 10/21/2019] [Accepted: 11/13/2019] [Indexed: 11/19/2022]
Abstract
Long interspersed nuclear elements 1 (LINE1) are non-LTR retrotransposons that represent the greatest remodeling force of the human genome during evolution. Genomically, LINE1 are constituted by a 5´ untranslated region (UTR), where the promoter regions are located, three open reading frames (ORF0, ORF1, and ORF2) and one 3´UTR, which has a poly(A) tail that harbors the short interspersed nuclear elements (SINEs) Alu and SVA. Although the intrinsic nature of LINE1 is to be copied and inserted into the genome, an increase in their mobility produces genomic instability. In response to this, the cell has "designed" many mechanisms controlling the retrotransposition levels of LINE1; however, alterations in these regulation systems can increase LINE1 mobility and the formation of chimeric genes. Evidence indicates that 988 human genes have LINE1 inserted in their sequence, resulting in the transcriptional control of genes by their own promoters, as well as by the LINE1 antisense promoter (ASP). To date, very little is known about the biologic impact of this and the L1-MET chimera is a more or less studied case. ASP hypomethylation has been observed in all studied cancer types, leading to increased L1-MET expression. In specific types of cancer, this L1-MET increase controls both low and high MET protein levels. It remains to be clarified if this protein product is a chimeric protein.
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Affiliation(s)
- Andrea Cervantes-Ayalc
- Laboratorio de RNAs no codificantes, Unidad de Investigación Médica en Genética Humana del Hospital de Pediatría "Silvestre Frenk Freund", Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), CDMX 06720, México.
| | - Ruth Ruiz Esparza-Garrido
- Catedrática CONACyT, Laboratorio de RNAs no codificantes, Unidad de Investigación Médica en Genética Humana del Hospital de Pediatría "Silvestre Frenk Freund", Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), CDMX 06720, México; Laboratorio de RNAs no codificantes, Unidad de Investigación Médica en Genética Humana del Hospital de Pediatría "Silvestre Frenk Freund", Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), CDMX 06720, México.
| | - Miguel Ángel Velázquez-Flores
- Laboratorio de RNAs no codificantes, Unidad de Investigación Médica en Genética Humana del Hospital de Pediatría "Silvestre Frenk Freund", Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), CDMX 06720, México; Laboratorio de RNAs no codificantes, Unidad de Investigación Médica en Genética Humana del Hospital de Pediatría "Silvestre Frenk Freund", Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), Mexico.
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Saleh A, Macia A, Muotri AR. Transposable Elements, Inflammation, and Neurological Disease. Front Neurol 2019; 10:894. [PMID: 31481926 PMCID: PMC6710400 DOI: 10.3389/fneur.2019.00894] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 08/02/2019] [Indexed: 12/13/2022] Open
Abstract
Transposable Elements (TE) are mobile DNA elements that can replicate and insert themselves into different locations within the host genome. Their propensity to self-propagate has a myriad of consequences and yet their biological significance is not well-understood. Indeed, retrotransposons have evaded evolutionary attempts at repression and may contribute to somatic mosaicism. Retrotransposons are emerging as potent regulatory elements within the human genome. In the diseased state, there is mounting evidence that endogenous retroelements play a role in etiopathogenesis of inflammatory diseases, with a disposition for both autoimmune and neurological disorders. We postulate that active mobile genetic elements contribute more to human disease pathogenesis than previously thought.
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Affiliation(s)
- Aurian Saleh
- Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA, United States
| | - Angela Macia
- Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA, United States
| | - Alysson R Muotri
- Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA, United States
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25
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Abstract
Maintenance of genome stability requires control over the expression of transposable elements (TEs), whose activity can have substantial deleterious effects on the host. Chemical modification of DNA is a commonly used strategy to achieve this, and it has long been argued that the emergence of 5-methylcytosine (5mC) in many species was driven by the requirement to silence TEs. Potential roles in TE regulation have also been suggested for other DNA modifications, such as N6-methyladenine and oxidation derivatives of 5mC, although the underlying mechanistic relationships are poorly understood. Here, we discuss current evidence implicating DNA modifications and DNA-modifying enzymes in TE regulation across different species.
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Affiliation(s)
- Özgen Deniz
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London, UK
| | - Jennifer M Frost
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London, UK
| | - Miguel R Branco
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London, UK.
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26
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Abstract
Transposable elements (TEs) are low-complexity elements (e.g., LINEs, SINEs, SVAs, and HERVs) that make up to two-thirds of the human genome. There is mounting evidence that TEs play an essential role in molecular functions that influence genomic plasticity and gene expression regulation. With the advent of next-generation sequencing approaches, our understanding of the relationship between TEs and psychiatric disorders will greatly improve. In this chapter, the Authors comprehensively summarize the state-of the-art of TE research in animal models and humans supporting a framework in which TEs play a functional role in mechanisms affecting a variety of behaviors, including neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Finally, the Authors discuss recent therapeutic applications raised from the increasing experimental evidence on TE functional mechanisms.
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Affiliation(s)
- G Guffanti
- McLean Hospital - Harvard Medical School, Belmont, MA, USA.
| | - A Bartlett
- Department of Psychology, University of Massachusetts, Boston, Boston, MA, USA
| | - P DeCrescenzo
- McLean Hospital - Harvard Medical School, Belmont, MA, USA
| | - F Macciardi
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - R Hunter
- Department of Psychology, University of Massachusetts, Boston, Boston, MA, USA
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27
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Kerachian MA, Kerachian M. Long interspersed nucleotide element-1 (LINE-1) methylation in colorectal cancer. Clin Chim Acta 2018; 488:209-214. [PMID: 30445031 DOI: 10.1016/j.cca.2018.11.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 11/11/2018] [Accepted: 11/12/2018] [Indexed: 02/06/2023]
Abstract
Colorectal cancer (CRC) represents a group of molecularly heterogeneous diseases characterized by genetic and epigenetic alterations. Long interspersed nuclear elements (LINEs) are a form of retrotransposable element found in many eukaryotic genomes. These LINEs, when active, can mobilize in the cell and steadily cause genomic rearrangement. Active LINE reorganization is a source of endogenous mutagenesis and polymorphism in the cell that brings about individual genomic variation. In normal somatic cells, these elements are heavily methylated and thus mostly suppressed, in turn, preventing their potential for bringing about genomic instability. When LINEs are inadequately controlled, they can play a role in the pathogenesis of several genetic diseases, such as cancer. In tumor cells, LINE hypomethylation can reactivate the mobilization of these elements and is associated with both an advanced stage and a poor prognosis. In this article, we summarize the current knowledge surrounding LINE methylation, its correlation to CRC and its application as a diagnostic, prognostic and predictive biomarker in colon cancer.
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Affiliation(s)
- Mohammad Amin Kerachian
- Medical Genetics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.; Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran; Cancer Genetics Research Unit, Reza Radiotherapy and Oncology Center, Mashhad, Iran.
| | - Matin Kerachian
- Faculty of Medicine, McGill University, Montreal, Canada; Research Institute at McGill University Health Center, Montreal, Canada
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28
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Miglio U, Berrino E, Panero M, Ferrero G, Coscujuela Tarrero L, Miano V, Dell'Aglio C, Sarotto I, Annaratone L, Marchiò C, Comoglio PM, De Bortoli M, Pasini B, Venesio T, Sapino A. The expression of LINE1-MET chimeric transcript identifies a subgroup of aggressive breast cancers. Int J Cancer 2018; 143:2838-2848. [PMID: 30144023 DOI: 10.1002/ijc.31831] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 07/17/2018] [Accepted: 08/15/2018] [Indexed: 01/03/2023]
Abstract
Demethylation of the long interspersed nuclear element (LINE-1; L1) antisense promoter can result in transcription of neighboring sequences as for the L1-MET transcript produced by the L1 placed in the second intron of MET. To define the role of L1-MET, we investigated the sequence and the transcription of L1-MET in vitro models and heterogeneous breast cancers, previously reported to show other L1-derived transcripts. L1-MET expressing cell lines were initially identified in silico and investigated for L1-MET promoter methylation, cDNA sequence and cell fraction mRNA. The transcriptional level of L1-MET and MET were then evaluated in breast specimens, including 9 cancer cell lines, 41 carcinomas of different subtypes, and 11 normal tissues. In addition to a L1-MET transcript ending at MET exon 21, six novel L1-MET splice variants were identified. Normal breast tissues were negative for the L1-MET expression, whereas the triple-negative breast cancer (TNBC) and the high-grade carcinomas were enriched with the L1-MET mRNA (p = 0.005 and p = 0.018, respectively). In cancer cells and tissues the L1-MET expression was associated with its promoter hypomethylation (ρ = -0.8 and -0.9, respectively). No correlation was found between L1-MET and MET mRNA although L1-MET expressing tumors with higher L1-MET/MET ratio were negative for the MET protein expression (p = 0.006). Besides providing the first identification and detailed description of L1-MET in breast cancer, we clearly demonstrate that higher levels of this transcript specifically recognize a subset of more aggressive carcinomas, mainly TNBC. We suggest the possible evaluation of L1-MET in the challenging diagnosis of early TNBCs.
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Affiliation(s)
- Umberto Miglio
- Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy
| | - Enrico Berrino
- Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy
| | - Mara Panero
- Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy
| | - Giulio Ferrero
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Italy.,Department of Computer Science, University of Turin, Turin, Italy
| | | | - Valentina Miano
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Italy
| | - Carmine Dell'Aglio
- Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy
| | - Ivana Sarotto
- Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy
| | - Laura Annaratone
- Department of Medical Sciences, University of Turin, Turin, Italy
| | - Caterina Marchiò
- Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy.,Department of Medical Sciences, University of Turin, Turin, Italy
| | - Paolo M Comoglio
- Molecular Therapeutics and Exploratory Research Laboratory, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy
| | - Michele De Bortoli
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Italy
| | - Barbara Pasini
- Department of Medical Sciences, University of Turin, Turin, Italy
| | - Tiziana Venesio
- Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy
| | - Anna Sapino
- Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy.,Department of Medical Sciences, University of Turin, Turin, Italy
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29
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Baba Y, Yagi T, Sawayama H, Hiyoshi Y, Ishimoto T, Iwatsuki M, Miyamoto Y, Yoshida N, Baba H. Long Interspersed Element-1 Methylation Level as a Prognostic Biomarker in Gastrointestinal Cancers. Digestion 2018; 97:26-30. [PMID: 29393154 DOI: 10.1159/000484104] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Epigenetic changes play a crucial role in human cancer development. DNA methylation is a central epigenetic process that regulates levels of gene expression. Changes in DNA methylation that occur in human tumors include global DNA hypomethylation and site-specific CpG island promoter hypermethylation. Long interspersed element-1 (LINE-1) is a repetitive DNA retrotransposon that duplicates via a copy-and-paste genetic mechanism. As LINE-1 constitutes approximately 17% of the human genome, the extent of LINE-1 methylation is regarded as a surrogate marker of global DNA methylation. In a variety of gastrointestinal (GI) cancers, LINE-1 hypomethylation is strongly associated with a poor prognosis, supporting its potential role as a prognostic biomarker. In this article, we summarize current knowledge regarding LINE-1 methylation and its prognostic impact in GI cancers.
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Prognostic value of LINE-1 methylation level in 321 patients with primary liver cancer including hepatocellular carcinoma and intrahepatic cholangiocarcinoma. Oncotarget 2018; 9:20795-20806. [PMID: 29755690 PMCID: PMC5945516 DOI: 10.18632/oncotarget.25124] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 03/22/2018] [Indexed: 12/30/2022] Open
Abstract
Background The methylation level of long interspersed nucleotide element-1 (LINE-1) is a good surrogate marker of the global DNA methylation level. The relationship between LINE-1 methylation level and prognosis in primary liver cancer (PLC) patients remains unclear. Results LINE-1 methylation levels were significantly lower in HCC and cHCC-CC tissues, but not in ICC tissues, than those in noncancerous liver parenchyma (HCC: p < 0.0001; cHCC-CC: p < 0.001; and ICC: p = 0.053). HCC cases with hypomethylated LINE-1 had significantly shorter relapse-free survival (RFS) (log-rank, p = 0.008); however, this was not observed for the cHCC-CC or ICC cases. Multivariate Cox regression analysis revealed a significantly higher HCC recurrence rate in the group with hypomethylated LINE-1 (hazard ratio, 1.62; 95% confidence interval, 1.06-2.58; p = 0.025). Conclusions The genome-wide DNA hypomethylation status estimated via LINE-1 methylation levels might be indicative of poor RFS in patients with HCC but not ICC or cHCC-CC. Methods We evaluated the level of LINE-1 methylation in 321 cases of curatively resected PLC {231 hepatocellular carcinoma (HCC), 19 combined hepatocellular and cholangiocarcinoma (cHCC-CC) and 71 intrahepatic cholangiocarcinoma (ICC)} via pyrosequencing of formalin-fixed paraffin-embedded (FFPE) tissues and examined its prognostic value.
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31
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Ishiguro K, Higashino S, Hirakawa H, Sato S, Aizawa Y. Establishment of a genome-wide and quantitative protocol for assessment of transcriptional activity at human retrotransposon L1 antisense promoters. Genes Genet Syst 2018; 92:243-249. [PMID: 28381655 DOI: 10.1266/ggs.16-00053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Long interspersed element 1 (L1) retrotransposon sequences are widespread in the human genome, occupying ~500,000 locations. The majority of L1s have lost their retrotransposition capability, although a significant population of human L1s maintains bidirectional transcriptional activity from the internal promoter. While the sense promoter drives transcription of the entire L1 mRNA and leads to L1 retrotransposition, the antisense promoter (ASP) transcribes L1-gene chimeric RNAs that include neighboring exon sequences. Activation mechanisms and functional impacts of L1ASP transcription are thought to vary at every L1ASP location. To explore the locus-specific regulation and function of L1ASP transcription, quantitative methodology is necessary for identifying the genomic positions of highly active L1ASPs on a genome-wide scale. Here, we employed deep-sequencing techniques and built a 3' RACE-based experimental and bioinformatics protocol, named the L1 antisense transcriptome protocol (LATRAP). In LATRAP, the PCR primer and the read mapping scheme were designed to reduce false positives and negatives, which may have been included as hits in previous cloning studies. LATRAP was here applied to the A549 human lung cancer cell line, and 313 L1ASP loci were detected to have transcriptional activity but differed in the number of mapped reads by four orders of magnitude. This indicates that transcriptional activities of the individual L1ASPs can vary greatly and that only a small population of L1ASP loci is active within individual nuclei. LATRAP is the first experimental method for ranking L1ASPs according to their transcriptional activity and will thus open a new avenue to unveiling the locus-specific biology of L1ASPs.
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Affiliation(s)
- Koichi Ishiguro
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology
| | - Saneyuki Higashino
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology
| | | | | | - Yasunori Aizawa
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology.,Center for Biological Resources and Informatics, Tokyo Institute of Technology
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32
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Clinical and biological significance of miR-23b and miR-193a in human hepatocellular carcinoma. Oncotarget 2018; 8:6955-6969. [PMID: 28036298 PMCID: PMC5351682 DOI: 10.18632/oncotarget.14332] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 12/16/2016] [Indexed: 12/22/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the most common cancer of the liver with a very poor prognosis. The dysregulation of microRNAs (miRs) is indeed implicated in HCC onset and progression. In this study, we have evaluated the expression of miR-23b and miR-193a in a large cohort of 59 and 67 HCC patients, respectively. miR-23b and miR-193a resulted significantly down-regulated in primary HCCs compared to their matched peritumoral counterparts. Furthermore, patients with higher miR-193a expression exhibited longer OS and DFS, suggesting that miR-193a may be a molecular prognostic factor for HCC patients. Since the regulation of miRs by DNA methylation may occur in human cancers, we verified whether the down-modulation of miR-23b and miR-193a in HCC tissues could be related to DNA methylation. An inverse trend between miR-23b expression and DNA methylation was observed, indicating that miR-23b can be epigenetically regulated. By contrast, the down-regulation of miR-193a was not mediated by DNA methylation. To verify the potential role of miR-23b and miR-193a as responsive molecular targets in vitro, we used the inhibitor of DNA methylation 5-aza-dC to restore miR-23b expression level in combination with miR-193a transfection. The combined treatment led to a significant inhibition of cellular proliferation and migration. Taken together, our findings provide evidence that miR-23b and miR-193a may be molecular diagnostic and prognostic factors for HCC; furthermore, miR-23b and miR-193a are responsive molecular targets for limiting HCC cell aggressiveness in combination with the epigenetic drug 5-aza-dC. Moreover, our results provide new advances in the epigenetic regulation of these miRs in HCC.
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Nakamura K, Baba Y, Kosumi K, Harada K, Shigaki H, Miyake K, Kiyozumi Y, Ohuchi M, Kurashige J, Ishimoto T, Iwatsuki M, Sakamoto Y, Yoshida N, Watanabe M, Nakao M, Baba H. UHRF1 regulates global DNA hypomethylation and is associated with poor prognosis in esophageal squamous cell carcinoma. Oncotarget 2018; 7:57821-57831. [PMID: 27507047 PMCID: PMC5295392 DOI: 10.18632/oncotarget.11067] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 07/19/2016] [Indexed: 01/27/2023] Open
Abstract
Background Global DNA hypomethylation contributes to oncogenesis through various mechanisms. The level of long interspersed nucleotide element-1 (LINE- 1) methylation is considered a surrogate marker of global DNA methylation, and is attracting interest as a good predictor of cancer prognosis. However, the mechanism how LINE-1 (global DNA) methylation is controlled in cancer cells remains to be fully elucidated. Ubiquitin-like with PHD and RING finger domain 1 (UHRF1) plays a crucial role in DNA methylation. UHRF1 is overexpressed in many cancers, and UHRF1 overexpression may be a mechanism underlying DNA hypomethylation in cancer cells. Nonetheless, the relationship between UHRF1, LINE-1 methylation level, and clinical outcome in esophageal squamous cell carcinoma (ESCC) remains unclear. Results In ESCC cell lines, vector-mediated UHRF1 overexpression caused global DNA (LINE-1) hypomethylation and, conversely, UHRF1 knockdown using siRNA increased the global DNA methylation level. In ESCC tissues, UHRF1 expression was significantly associated with LINE-1 methylation levels. Furthermore, UHRF1 overexpression correlated with poor prognosis in our cohort of 160 ESCC patients. Materials and Methods The relationships between UHRF1 expression and LINE-1 methylation level (i.e., global DNA methylation level) were investigated using ESCC tissues and cell lines. In addition, we examined the correlation between UHRF1 expression, LINE-1 methylation, and clinical outcome in patients with ESCC. Conclusions Our results suggest that UHRF1 is a key epigenetic regulator of DNA methylation and might be a potential target for cancer treatment.
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Affiliation(s)
- Kenichi Nakamura
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Yoshifumi Baba
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Keisuke Kosumi
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Kazuto Harada
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Hironobu Shigaki
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Keisuke Miyake
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Yuki Kiyozumi
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Mayuko Ohuchi
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Junji Kurashige
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Takatsugu Ishimoto
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Masaaki Iwatsuki
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Yasuo Sakamoto
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Naoya Yoshida
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Masayuki Watanabe
- Department of Gastroenterological Surgery, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Mitsuyoshi Nakao
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
| | - Hideo Baba
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
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Lock FE, Babaian A, Zhang Y, Gagnier L, Kuah S, Weberling A, Karimi MM, Mager DL. A novel isoform of IL-33 revealed by screening for transposable element promoted genes in human colorectal cancer. PLoS One 2017; 12:e0180659. [PMID: 28715472 PMCID: PMC5513427 DOI: 10.1371/journal.pone.0180659] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/19/2017] [Indexed: 02/06/2023] Open
Abstract
Remnants of ancient transposable elements (TEs) are abundant in mammalian genomes. These sequences contain multiple regulatory motifs and hence are capable of influencing expression of host genes. TEs are known to be released from epigenetic repression and can become transcriptionally active in cancer. Such activation could also lead to lineage-inappropriate activation of oncogenes, as previously described in lymphomas. However, there are few reports of this mechanism occurring in non-blood cancers. Here, we re-analyzed whole transcriptome data from a large cohort of patients with colon cancer, compared to matched normal colon control samples, to detect genes or transcripts ectopically expressed through activation of TE promoters. Among many such transcripts, we identified six where the affected gene has described role in cancer and where the TE-driven gene mRNA is expressed in primary colon cancer, but not normal matched tissue, and confirmed expression in colon cancer-derived cell lines. We further characterized a TE-gene chimeric transcript involving the Interleukin 33 (IL-33) gene (termed LTR-IL-33), that is ectopically expressed in a subset of colon cancer samples through the use of an endogenous retroviral long terminal repeat (LTR) promoter of the MSTD family. The LTR-IL-33 chimeric transcript encodes a novel shorter isoform of the protein, which is missing the initial N-terminus (including many conserved residues) of Native IL-33. In vitro studies showed that LTR-IL-33 expression is required for optimal CRC cell line growth as 3D colonospheres. Taken together, these data demonstrate the significance of TEs as regulators of aberrant gene expression in colon cancer.
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Affiliation(s)
- Frances E. Lock
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Artem Babaian
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Ying Zhang
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Liane Gagnier
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Sabrina Kuah
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Antonia Weberling
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Mohammad M. Karimi
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
- Département de Génomique Fonctionnelle et Cancer, Institut de Génétique et Biologie Moléculaire et Cellulaire (IGBMC)/Université de Strasbourg/CNRS/INSERM, France
| | - Dixie L. Mager
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
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Abstract
Transposable elements give rise to interspersed repeats, sequences that comprise most of our genomes. These mobile DNAs have been historically underappreciated - both because they have been presumed to be unimportant, and because their high copy number and variability pose unique technical challenges. Neither impediment now seems steadfast. Interest in the human mobilome has never been greater, and methods enabling its study are maturing at a fast pace. This Review describes the activity of transposable elements in human cancers, particularly long interspersed element-1 (LINE-1). LINE-1 sequences are self-propagating, protein-coding retrotransposons, and their activity results in somatically acquired insertions in cancer genomes. Altered expression of transposable elements and animation of genomic LINE-1 sequences appear to be hallmarks of cancer, and can be responsible for driving mutations in tumorigenesis.
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Affiliation(s)
- Kathleen H Burns
- Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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36
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Transposable elements in cancer. NATURE REVIEWS. CANCER 2017. [PMID: 28642606 DOI: 10.1038/nrc.2017.35+[doi]] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Transposable elements give rise to interspersed repeats, sequences that comprise most of our genomes. These mobile DNAs have been historically underappreciated - both because they have been presumed to be unimportant, and because their high copy number and variability pose unique technical challenges. Neither impediment now seems steadfast. Interest in the human mobilome has never been greater, and methods enabling its study are maturing at a fast pace. This Review describes the activity of transposable elements in human cancers, particularly long interspersed element-1 (LINE-1). LINE-1 sequences are self-propagating, protein-coding retrotransposons, and their activity results in somatically acquired insertions in cancer genomes. Altered expression of transposable elements and animation of genomic LINE-1 sequences appear to be hallmarks of cancer, and can be responsible for driving mutations in tumorigenesis.
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37
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Vafadar-Isfahani N, Parr C, McMillan LE, Sanner J, Yeo Z, Saddington S, Peacock O, Cruickshanks HA, Meehan RR, Lund JN, Tufarelli C. Decoupling of DNA methylation and activity of intergenic LINE-1 promoters in colorectal cancer. Epigenetics 2017; 12:465-475. [PMID: 28300471 PMCID: PMC5501206 DOI: 10.1080/15592294.2017.1300729] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 02/17/2017] [Accepted: 02/23/2017] [Indexed: 01/02/2023] Open
Abstract
Hypomethylation of LINE-1 repeats in cancer has been proposed as the main mechanism behind their activation; this assumption, however, was based on findings from early studies that were biased toward young and transpositionally active elements. Here, we investigate the relationship between methylation of 2 intergenic, transpositionally inactive LINE-1 elements and expression of the LINE-1 chimeric transcript (LCT) 13 and LCT14 driven by their antisense promoters (L1-ASP). Our data from DNA modification, expression, and 5'RACE analyses suggest that colorectal cancer methylation in the regions analyzed is not always associated with LCT repression. Consistent with this, in HCT116 colorectal cancer cells lacking DNA methyltransferases DNMT1 or DNMT3B, LCT13 expression decreases, while cells lacking both DNMTs or treated with the DNMT inhibitor 5-azacytidine (5-aza) show no change in LCT13 expression. Interestingly, levels of the H4K20me3 histone modification are inversely associated with LCT13 and LCT14 expression. Moreover, at these LINE-1s, H4K20me3 levels rather than DNA methylation seem to be good predictor of their sensitivity to 5-aza treatment. Therefore, by studying individual LINE-1 promoters we have shown that in some cases these promoters can be active without losing methylation; in addition, we provide evidence that other factors (e.g., H4K20me3 levels) play prominent roles in their regulation.
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Affiliation(s)
| | - Christina Parr
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, UK
| | - Lara E. McMillan
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, UK
| | - Juliane Sanner
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, UK
| | - Zhao Yeo
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, UK
| | - Stephen Saddington
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, UK
| | - Oliver Peacock
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, UK
| | | | - Richard R. Meehan
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Jonathan N. Lund
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, UK
| | - Cristina Tufarelli
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, UK
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Li S, Shuch BM, Gerstein MB. Whole-genome analysis of papillary kidney cancer finds significant noncoding alterations. PLoS Genet 2017; 13:e1006685. [PMID: 28358873 PMCID: PMC5391127 DOI: 10.1371/journal.pgen.1006685] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 04/13/2017] [Accepted: 03/13/2017] [Indexed: 01/30/2023] Open
Abstract
To date, studies on papillary renal-cell carcinoma (pRCC) have largely focused on coding alterations in traditional drivers, particularly the tyrosine-kinase, Met. However, for a significant fraction of tumors, researchers have been unable to determine a clear molecular etiology. To address this, we perform the first whole-genome analysis of pRCC. Elaborating on previous results on MET, we find a germline SNP (rs11762213) in this gene predicting prognosis. Surprisingly, we detect no enrichment for small structural variants disrupting MET. Next, we scrutinize noncoding mutations, discovering potentially impactful ones associated with MET. Many of these are in an intron connected to a known, oncogenic alternative-splicing event; moreover, we find methylation dysregulation nearby, leading to a cryptic promoter activation. We also notice an elevation of mutations in the long noncoding RNA NEAT1, and these mutations are associated with increased expression and unfavorable outcome. Finally, to address the origin of pRCC heterogeneity, we carry out whole-genome analyses of mutational processes. First, we investigate genome-wide mutational patterns, finding they are governed mostly by methylation-associated C-to-T transitions. We also observe significantly more mutations in open chromatin and early-replicating regions in tumors with chromatin-modifier alterations. Finally, we reconstruct cancer-evolutionary trees, which have markedly different topologies and suggested evolutionary trajectories for the different subtypes of pRCC.
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Affiliation(s)
- Shantao Li
- Program in Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut, United States of America
| | - Brian M. Shuch
- Department of Urology, Yale School of Medicine, New Haven, Connecticut, United States of America
| | - Mark B. Gerstein
- Program in Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut, United States of America
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- Department of Computer Science, Yale University, New Haven, Connecticut, United States of America
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Ardeljan D, Taylor MS, Ting DT, Burns KH. The Human Long Interspersed Element-1 Retrotransposon: An Emerging Biomarker of Neoplasia. Clin Chem 2017; 63:816-822. [PMID: 28188229 DOI: 10.1373/clinchem.2016.257444] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 11/22/2016] [Indexed: 02/06/2023]
Abstract
BACKGROUND A large portion of intronic and intergenic space in our genome consists of repeated sequences. One of the most prevalent is the long interspersed element-1 (LINE-1, L1) mobile DNA. LINE-1 is rightly receiving increasing interest as a cancer biomarker. CONTENT Intact LINE-1 elements are self-propagating. They code for RNA and proteins that function to make more copies of the genomic element. Our current understanding is that this process is repressed in most normal cells, but that LINE-1 expression is a hallmark of many types of malignancy. Here, we will consider features of cancer cells when cellular defense mechanisms repressing LINE-1 go awry. We will review evidence that genomic LINE-1 methylation, LINE-1-encoded RNAs, and LINE-1 ORF1p (open reading frame 1 protein) may be useful in cancer diagnosis. SUMMARY The repetitive and variable nature of LINE-1 DNA sequences poses unique challenges to studying them, but recent advances in reagents and next generation sequencing present opportunities to characterize LINE-1 expression and activity in cancers and to identify clinical applications.
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Affiliation(s)
- Daniel Ardeljan
- McKusick-Nathans Institute of Genetic Medicine (IGM) and.,Medical Scientist Training Program (MSTP), Johns Hopkins University School of Medicine, Baltimore, MD
| | - Martin S Taylor
- Department of Pathology, Massachusetts General Hospital, Boston, MA
| | - David T Ting
- Department of Medicine and the Massachusetts General Hospital Cancer Center, Boston, MA
| | - Kathleen H Burns
- McKusick-Nathans Institute of Genetic Medicine (IGM) and .,Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
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Furlan D, Trapani D, Berrino E, Debernardi C, Panero M, Libera L, Sahnane N, Riva C, Tibiletti MG, Sessa F, Sapino A, Venesio T. Oxidative DNA damage induces hypomethylation in a compromised base excision repair colorectal tumourigenesis. Br J Cancer 2017; 116:793-801. [PMID: 28141798 PMCID: PMC5355935 DOI: 10.1038/bjc.2017.9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/23/2016] [Accepted: 01/05/2017] [Indexed: 12/12/2022] Open
Abstract
Background: A compromised base excision repair (BER) promotes carcinogenesis by accumulating oxidative DNA-damaged products as observed in MUTYH-associated polyposis, a hereditary colorectal cancer syndrome marked by adenomas and cancers with an accumulation of 8-oxoguanine. Remarkably, DNA global demethylation has been shown to be mediated by BER, suggesting a relevant interplay with early colorectal tumourigenesis. To check this hypothesis, we investigated a cohort of 49 adenomas and 10 carcinomas, derived from 17 MUTYH-associated polyposis patients; as adenoma controls, we used a set of 36 familial adenomatous polyposis and 24 sporadic polyps. Methods: Samples were analysed for their mutational and epigenetic status, measured as global LINE-1 (long interspersed nuclear element) and gene-specific LINE-1 MET methylation by mass spectrometry and pyrosequencing. Results: MUTYH-associated polyposis adenomas were strikingly more hypomethylated than familial adenomatous and sporadic polyps for both DNA demethylation markers (P=0.032 and P=0.007 for LINE-1; P=0.004 and P<0.0001 for LINE-1 MET, respectively) with levels comparable to those of the carcinomas derived from the same patients. They also had mutations due mainly to KRAS/NRAS p.G12C, which was absent in the controls (P<0.0001 for both sets). Conclusions: Our results show that DNA demethylation, together with specific KRAS/NRAS mutations, drives the early steps of oxidative damage colorectal tumourigenesis.
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Affiliation(s)
- Daniela Furlan
- Anatomic Pathology Unit, Department of Surgical and Morphological Sciences, University of Insubria, Varese 21100, Italy.,Research Center for the Study of Hereditary and Familial Tumors, University of Insubria, Varese 21100, Italy
| | - Davide Trapani
- Anatomic Pathology Unit, Department of Surgical and Morphological Sciences, University of Insubria, Varese 21100, Italy
| | - Enrico Berrino
- Molecular Pathology Laboratory, Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Strada Provinciale 142, Candiolo (Torino) 10060, Italy
| | - Carla Debernardi
- Molecular Pathology Laboratory, Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Strada Provinciale 142, Candiolo (Torino) 10060, Italy
| | - Mara Panero
- Molecular Pathology Laboratory, Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Strada Provinciale 142, Candiolo (Torino) 10060, Italy
| | - Laura Libera
- Anatomic Pathology Unit, Department of Surgical and Morphological Sciences, University of Insubria, Varese 21100, Italy
| | - Nora Sahnane
- Anatomic Pathology Unit, Department of Surgical and Morphological Sciences, University of Insubria, Varese 21100, Italy
| | - Cristina Riva
- Anatomic Pathology Unit, Department of Surgical and Morphological Sciences, University of Insubria, Varese 21100, Italy.,Research Center for the Study of Hereditary and Familial Tumors, University of Insubria, Varese 21100, Italy
| | - Maria Grazia Tibiletti
- Anatomic Pathology Unit, Department of Surgical and Morphological Sciences, University of Insubria, Varese 21100, Italy
| | - Fausto Sessa
- Anatomic Pathology Unit, Department of Surgical and Morphological Sciences, University of Insubria, Varese 21100, Italy.,Research Center for the Study of Hereditary and Familial Tumors, University of Insubria, Varese 21100, Italy
| | - Anna Sapino
- Molecular Pathology Laboratory, Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Strada Provinciale 142, Candiolo (Torino) 10060, Italy
| | - Tiziana Venesio
- Molecular Pathology Laboratory, Unit of Pathology, Candiolo Cancer Institute, FPO-IRCCS, Strada Provinciale 142, Candiolo (Torino) 10060, Italy
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Babaian A, Mager DL. Endogenous retroviral promoter exaptation in human cancer. Mob DNA 2016; 7:24. [PMID: 27980689 PMCID: PMC5134097 DOI: 10.1186/s13100-016-0080-x] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 11/11/2016] [Indexed: 12/13/2022] Open
Abstract
Cancer arises from a series of genetic and epigenetic changes, which result in abnormal expression or mutational activation of oncogenes, as well as suppression/inactivation of tumor suppressor genes. Aberrant expression of coding genes or long non-coding RNAs (lncRNAs) with oncogenic properties can be caused by translocations, gene amplifications, point mutations or other less characterized mechanisms. One such mechanism is the inappropriate usage of normally dormant, tissue-restricted or cryptic enhancers or promoters that serve to drive oncogenic gene expression. Dispersed across the human genome, endogenous retroviruses (ERVs) provide an enormous reservoir of autonomous gene regulatory modules, some of which have been co-opted by the host during evolution to play important roles in normal regulation of genes and gene networks. This review focuses on the “dark side” of such ERV regulatory capacity. Specifically, we discuss a growing number of examples of normally dormant or epigenetically repressed ERVs that have been harnessed to drive oncogenes in human cancer, a process we term onco-exaptation, and we propose potential mechanisms that may underlie this phenomenon.
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Affiliation(s)
- Artem Babaian
- Terry Fox Laboratory, British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z1L3 Canada ; Department of Medical Genetics, University of British Columbia, Vancouver, BC Canada
| | - Dixie L Mager
- Terry Fox Laboratory, British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z1L3 Canada ; Department of Medical Genetics, University of British Columbia, Vancouver, BC Canada
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Criscione SW, Theodosakis N, Micevic G, Cornish TC, Burns KH, Neretti N, Rodić N. Genome-wide characterization of human L1 antisense promoter-driven transcripts. BMC Genomics 2016; 17:463. [PMID: 27301971 PMCID: PMC4908685 DOI: 10.1186/s12864-016-2800-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 05/26/2016] [Indexed: 11/23/2022] Open
Abstract
Background Long INterspersed Element-1 (LINE-1 or L1) is the only autonomously active, transposable element in the human genome. L1 sequences comprise approximately 17 % of the human genome, but only the evolutionarily recent, human-specific subfamily is retrotransposition competent. The L1 promoter has a bidirectional orientation containing a sense promoter that drives the transcription of two proteins required for retrotransposition and an antisense promoter. The L1 antisense promoter can drive transcription of chimeric transcripts: 5’ L1 antisense sequences spliced to the exons of neighboring genes. Results The impact of L1 antisense promoter activity on cellular transcriptomes is poorly understood. To investigate this, we analyzed GenBank ESTs for messenger RNAs that initiate in the L1 antisense promoter. We identified 988 putative L1 antisense chimeric transcripts, 911 of which have not been previously reported. These appear to be alternative genic transcripts, sense-oriented with respect to gene and initiating near, but typically downstream of, the gene transcriptional start site. In multiple cell lines, L1 antisense promoters display enrichment for YY1 transcription factor and histone modifications associated with active promoters. Global run-on sequencing data support the activity of the L1 antisense promoter. We independently detected 124 L1 antisense chimeric transcripts using long read Pacific Biosciences RNA-seq data. Furthermore, we validated four chimeric transcripts by quantitative RT-PCR and Sanger sequencing and demonstrated that they are readily detectable in many normal human tissues. Conclusions We present a comprehensive characterization of human L1 antisense promoter-driven transcripts and provide substantial evidence that they are transcribed in a variety of human cell-types. Our findings reveal a new wide-reaching aspect of L1 biology by identifying antisense transcripts affecting as many as 4 % of all human genes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2800-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Steven W Criscione
- Department of Molecular Biology, Cell Biology, and Biochemistry, Center for Computational Molecular Biology, Brown University, Providence, RI, 02912, USA
| | - Nicholas Theodosakis
- Department of Pathology, Yale University, New Haven, CT, 06510, USA.,Department of Dermatology, Division of Dermatopathology, Yale University, New Haven, CT, 06510, USA
| | - Goran Micevic
- Department of Pathology, Yale University, New Haven, CT, 06510, USA.,Department of Dermatology, Division of Dermatopathology, Yale University, New Haven, CT, 06510, USA
| | - Toby C Cornish
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kathleen H Burns
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,High Throughput (HiT) Biology Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nicola Neretti
- Department of Molecular Biology, Cell Biology, and Biochemistry, Center for Computational Molecular Biology, Brown University, Providence, RI, 02912, USA.
| | - Nemanja Rodić
- Department of Pathology, Yale University, New Haven, CT, 06510, USA. .,Department of Dermatology, Division of Dermatopathology, Yale University, New Haven, CT, 06510, USA.
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43
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Zhang J, Babic A. Regulation of the MET oncogene: molecular mechanisms. Carcinogenesis 2016; 37:345-55. [PMID: 26905592 DOI: 10.1093/carcin/bgw015] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 01/29/2016] [Indexed: 12/26/2022] Open
Abstract
The MET oncogene is a predictive biomarker and an attractive therapeutic target for various cancers. Its expression is regulated at multiple layers via various mechanisms. It is subject to epigenetic modifications, i.e. DNA methylation and histone acetylation. Hypomethylation and acetylation of the MET gene have been associated with its high expression in some cancers. Multiple transcription factors including Sp1 and Ets-1 govern its transcription. After its transcription, METmRNA is spliced into multiple species in the nucleus before being transported to the cytoplasm where its translation is modulated by at least 30 microRNAs and translation initiation factors, e.g. eIF4E and eIF4B. METmRNA produces a single chain pro-Met protein of 170 kDa which is cleaved into α and β chains. These two chains are bound together through disulfide bonds to form a heterodimer which undergoes either N-linked or O-linked glycosylation in the Golgi apparatus before it is properly localized in the membrane. Upon interactions with its ligand, i.e. hepatocyte growth factor (HGF), the activity of Met kinase is boosted through various phosphorylation mechanisms and the Met signal is relayed to downstream pathways. The phosphorylated Met is then internalized for subsequent degradation or recycle via proteasome, lysosome or endosome pathways. Moreover, the Met expression is subject to autoregulation and activation by other EGFRs and G-protein coupled receptors. Since deregulation of the MET gene leads to cancer and other pathological conditions, a better understanding of the MET regulation is critical for Met-targeted therapeutics.
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Affiliation(s)
- Jack Zhang
- Research and Development, Ventana Medical Systems, Inc., a Member of the Roche Group, Oro Valley, AZ 85755, USA
| | - Andy Babic
- Research and Development, Ventana Medical Systems, Inc., a Member of the Roche Group, Oro Valley, AZ 85755, USA
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44
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Lin S, Zhang L, Luo W, Zhang X. Characteristics of Antisense Transcript Promoters and the Regulation of Their Activity. Int J Mol Sci 2015; 17:E9. [PMID: 26703594 PMCID: PMC4730256 DOI: 10.3390/ijms17010009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 11/23/2015] [Accepted: 12/16/2015] [Indexed: 02/07/2023] Open
Abstract
Recently, an increasing number of studies on natural antisense transcripts have been reported, especially regarding their classification, temporal and spatial expression patterns, regulatory functions and mechanisms. It is well established that natural antisense transcripts are produced from the strand opposite to the strand encoding a protein. Despite the pivotal roles of natural antisense transcripts in regulating the expression of target genes, the transcriptional mechanisms initiated by antisense promoters (ASPs) remain unknown. To date, nearly all of the studies conducted on this topic have focused on the ASP of a single gene of interest, whereas no study has systematically analyzed the locations of ASPs in the genome, ASP activity, or factors influencing this activity. This review focuses on elaborating on and summarizing the characteristics of ASPs to extend our knowledge about the mechanisms of antisense transcript initiation.
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Affiliation(s)
- Shudai Lin
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, Guangzhou 510642, China.
- Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou 510642, China.
| | - Li Zhang
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, Guangzhou 510642, China.
- Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou 510642, China.
- Agricultural College, Guangdong Ocean University, Zhanjiang 524088, China.
| | - Wen Luo
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, Guangzhou 510642, China.
- Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou 510642, China.
| | - Xiquan Zhang
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, Guangzhou 510642, China.
- Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou 510642, China.
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Dhivya S, Premkumar K. Nomadic genetic elements contribute to oncogenic translocations: Implications in carcinogenesis. Crit Rev Oncol Hematol 2015; 98:81-93. [PMID: 26548742 DOI: 10.1016/j.critrevonc.2015.10.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 10/05/2015] [Accepted: 10/27/2015] [Indexed: 12/22/2022] Open
Abstract
Chromosomal translocations as molecular signatures have been reported in various malignancies but, the mechanism behind which is largely unknown. Swapping of chromosomal fragments occurs by induction of double strand breaks (DSBs), most of which were initially assumed de novo. However, decoding of human genome proved that transposable elements (TE) might have profound influence on genome integrity. TEs are highly conserved mobile genetic elements that generate DSBs, subsequently resulting in large chromosomal rearrangements. Previously TE insertions were thought to be harmless, but recently gains attention due to the origin of spectrum of post-insertional genomic alterations and subsequent transcriptional alterations leading to development of deleterious effects mainly carcinogenesis. Though the existing knowledge on the cancer-associated TE dynamics is very primitive, exploration of underlying mechanism promises better therapeutic strategies for cancer. Thus, this review focuses on the prevalence of TE in the genome, associated genomic instability upon transposition activation and impact on tumorigenesis.
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Affiliation(s)
- Sridaran Dhivya
- Cancer Genetics and Nanomedicine Laboratory, Department of Biomedical Science, School of Basic Medical Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India
| | - Kumpati Premkumar
- Cancer Genetics and Nanomedicine Laboratory, Department of Biomedical Science, School of Basic Medical Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India.
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The Fine LINE: Methylation Drawing the Cancer Landscape. BIOMED RESEARCH INTERNATIONAL 2015; 2015:131547. [PMID: 26448926 PMCID: PMC4584040 DOI: 10.1155/2015/131547] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 11/17/2014] [Accepted: 11/25/2014] [Indexed: 01/08/2023]
Abstract
LINE-1 (L1) is the most abundant mammalian transposable element that comprises nearly 20% of the genome, and nearly half of the mammalian genome has stemmed from L1-mediated mobilization. Expression and retrotransposition of L1 are suppressed by complex mechanisms, where the key role belongs to DNA methylation. Alterations in L1 methylation may lead to aberrant expression of L1 and have been described in numerous diseases. Accumulating evidence clearly indicates that loss of global DNA methylation observed in cancer development and progression is tightly associated with hypomethylation of L1 elements. Significant progress achieved in the last several years suggests that such parameters as L1 methylation status can be potentially utilized as clinical biomarkers for determination of the disease stage and in predicting the disease-free survival in cancer patients. In this paper, we summarize the current knowledge on L1 methylation, with specific emphasis given to success and challenges on the way of introduction of L1 into clinical practice.
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47
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Babaian A, Romanish MT, Gagnier L, Kuo LY, Karimi MM, Steidl C, Mager DL. Onco-exaptation of an endogenous retroviral LTR drives IRF5 expression in Hodgkin lymphoma. Oncogene 2015; 35:2542-6. [DOI: 10.1038/onc.2015.308] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 05/21/2015] [Accepted: 07/13/2015] [Indexed: 12/11/2022]
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Environmental Epigenetics: Crossroad between Public Health, Lifestyle, and Cancer Prevention. BIOMED RESEARCH INTERNATIONAL 2015; 2015:587983. [PMID: 26339624 PMCID: PMC4538403 DOI: 10.1155/2015/587983] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/01/2015] [Indexed: 12/31/2022]
Abstract
Epigenetics provides the key to transform the genetic information into phenotype and because of its reversibility it is considered an ideal target for therapeutic interventions. This paper reviews the basic mechanisms of epigenetic control: DNA methylation, histone modifications, chromatin remodeling, and ncRNA expression and their role in disease development. We describe also the influence of the environment, lifestyle, nutritional habits, and the psychological influence on epigenetic marks and how these factors are related to cancer and other diseases development. Finally we discuss the potential use of natural epigenetic modifiers in the chemoprevention of cancer to link together public health, environment, and lifestyle.
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50
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Harada K, Baba Y, Ishimoto T, Chikamoto A, Kosumi K, Hayashi H, Nitta H, Hashimoto D, Beppu T, Baba H. LINE-1 methylation level and patient prognosis in a database of 208 hepatocellular carcinomas. Ann Surg Oncol 2014; 22:1280-7. [PMID: 25319577 DOI: 10.1245/s10434-014-4134-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Indexed: 02/06/2023]
Abstract
BACKGROUND The level of long interspersed nucleotide element-1 (LINE-1) methylation has become regarded as a surrogate marker of global DNA methylation. Previously, we demonstrated that LINE-1 hypomethylation might contribute to the acquisition of aggressive tumor behavior through genomic gains of oncogenes such as cyclin-dependent kinase 6 (CDK6) in esophageal squamous cell carcinoma. However, the relationship between LINE-1 hypomethylation and clinical outcome in hepatocellular carcinoma (HCC) remains unclear. METHODS LINE-1 methylation level in 208 samples of curatively resected HCCs was measured by pyrosequencing assay, and the prognostic value of LINE-1 methylation level in HCC was examined. RESULTS LINE-1 methylation levels in the 208 HCC patients investigated were distributed as follows: mean 64.7; median 64.6; standard deviation (SD) 13.6; range 21.5-99.1; interquartile range 62.9-66.6. Univariate Cox regression analysis revealed a significantly higher cancer recurrence rate in the low-methylation-level group than in the high-methylation-level group (hazard ratio 1.58; 95 % CI 1.05-2.47; p = 0.028). Interestingly, the influence of LINE-1 hypomethylation on patient outcome was modified by hepatitis virus infection (p of interaction = 0.023); LINE-1 hypomethylation was associated with a higher cancer recurrence rate in patients without hepatitis virus infection (log-rank p = 0.0047). CDK6 messenger RNA expression levels were inversely associated with LINE-1 methylation levels (p = 0.0075; R = -0.37). CONCLUSIONS Genome-wide DNA hypomethylation, as measured by LINE-1 levels, might be associated with poor disease-free survival in HCC patients, suggesting a potential role for LINE-1 methylation level as a biomarker for identifying patients who will experience an unfavorable clinical outcome.
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Affiliation(s)
- Kazuto Harada
- Department of Gastroenterological Surgery, Graduate School of Medical Science, Kumamoto University, Kumamoto, Japan
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