1
|
Cherkasova EA, Chen L, Childs RW. Mechanistic regulation of HERV activation in tumors and implications for translational research in oncology. Front Cell Infect Microbiol 2024; 14:1358470. [PMID: 38379771 PMCID: PMC10877039 DOI: 10.3389/fcimb.2024.1358470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 01/22/2024] [Indexed: 02/22/2024] Open
Abstract
Transcription of distinct loci of human endogenous retroviruses (HERVs) and in some cases, translation of these transcripts have been consistently observed in many types of cancer. It is still debated whether HERV activation serves as a trigger for carcinogenesis or rather occurs as a consequence of epigenetic alterations and other molecular sequelae that characterize cellular transformation. Here we review the known molecular and epigenetic mechanisms of HERV activation in cancer cells as well as its potential contribution to carcinogenesis. Further, we describe the use of HERV expression in cancer diagnostic and characterize the potential of HERV-derived antigens to serve as novel targets for cancer immunotherapy. We believe this review, which summarizes both what is known as well as unknown in this rapidly developing field, will boost interest in research on the therapeutic potential of targeting HERV elements in tumors and the impact of HERV activation in oncogenesis.
Collapse
Affiliation(s)
| | | | - Richard W. Childs
- Laboratory of Transplantation Immunotherapy, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States
| |
Collapse
|
2
|
Stricker E, Peckham-Gregory EC, Scheurer ME. HERVs and Cancer-A Comprehensive Review of the Relationship of Human Endogenous Retroviruses and Human Cancers. Biomedicines 2023; 11:936. [PMID: 36979914 PMCID: PMC10046157 DOI: 10.3390/biomedicines11030936] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/03/2023] [Accepted: 03/10/2023] [Indexed: 03/30/2023] Open
Abstract
Genomic instability and genetic mutations can lead to exhibition of several cancer hallmarks in affected cells such as sustained proliferative signaling, evasion of growth suppression, activated invasion, deregulation of cellular energetics, and avoidance of immune destruction. Similar biological changes have been observed to be a result of pathogenic viruses and, in some cases, have been linked to virus-induced cancers. Human endogenous retroviruses (HERVs), once external pathogens, now occupy more than 8% of the human genome, representing the merge of genomic and external factors. In this review, we outline all reported effects of HERVs on cancer development and discuss the HERV targets most suitable for cancer treatments as well as ongoing clinical trials for HERV-targeting drugs. We reviewed all currently available reports of the effects of HERVs on human cancers including solid tumors, lymphomas, and leukemias. Our review highlights the central roles of HERV genes, such as gag, env, pol, np9, and rec in immune regulation, checkpoint blockade, cell differentiation, cell fusion, proliferation, metastasis, and cell transformation. In addition, we summarize the involvement of HERV long terminal repeat (LTR) regions in transcriptional regulation, creation of fusion proteins, expression of long non-coding RNAs (lncRNAs), and promotion of genome instability through recombination.
Collapse
Affiliation(s)
- Erik Stricker
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77047, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77047, USA
| | | | - Michael E. Scheurer
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77047, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77047, USA
| |
Collapse
|
3
|
Fan TJ, Cui J. Human Endogenous Retroviruses in Diseases. Subcell Biochem 2023; 106:403-439. [PMID: 38159236 DOI: 10.1007/978-3-031-40086-5_15] [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] [Indexed: 01/03/2024]
Abstract
Human endogenous retroviruses (HERVs), which are conserved sequences of ancient retroviruses, are widely distributed in the human genome. Although most HERVs have been rendered inactive by evolution, some have continued to exhibit important cytological functions. HERVs in the human genome perform dual functions: on the one hand, they are involved in important physiological processes such as placental development and immune regulation; on the other hand, their aberrant expression is closely associated with the pathological processes of several diseases, such as cancers, autoimmune diseases, and viral infections. HERVs can also regulate a variety of host cellular functions, including the expression of protein-coding genes and regulatory elements that have evolved from HERVs. Here, we present recent research on the roles of HERVs in viral infections and cancers, including the dysregulation of HERVs in various viral infections, HERV-induced epigenetic modifications of histones (such as methylation and acetylation), and the potential mechanisms of HERV-mediated antiviral immunity. We also describe therapies to improve the efficacy of vaccines and medications either by directly or indirectly targeting HERVs, depending on the HERV.
Collapse
Affiliation(s)
- Tian-Jiao Fan
- CAS Key Laboratory of Molecular Virology & Immunology, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China
| | - Jie Cui
- CAS Key Laboratory of Molecular Virology & Immunology, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China.
| |
Collapse
|
4
|
p53 Binding Sites in Long Terminal Repeat 5Hs (LTR5Hs) of Human Endogenous Retrovirus K Family (HML-2 Subgroup) Play Important Roles in the Regulation of LTR5Hs Transcriptional Activity. Microbiol Spectr 2022; 10:e0048522. [PMID: 35867400 PMCID: PMC9430305 DOI: 10.1128/spectrum.00485-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The long terminal repeats (LTRs) of human endogenous retroviruses (HERVs) are distributed throughout the human genome and provide favorable conditions to regulate the expression of their adjacent genes. HML-2 is the most biologically active subgroup of the HERV-K family, and expression of its members has been associated with many cancer types. The LTRs of HML-2 have been classified into three subgroups (LTR5A, LTR5B, and LTR5Hs) based on phylogenetic analyses. The current study aimed to explore the LTR transcriptional activity differences among the three subtypes and further explore the underlying factors. A total of 43 LTR5A elements, 62 LTR5B elements, and 194 LTR5Hs elements were selected. A phylogenetic tree showed that the LTR5Hs group was clearly separated from the LTR5A and LTR5B groups. A luciferase reporter assay indicated that LTR5Hs had the strongest promoter activity, followed by LTR5A and LTR5B. To investigate the underlying factors, LTR5Hs was divided into 4 sections, and the homologous fragments in LTR5B were replaced successively. Replacement of the third section (−263 to 0) significantly increased LTR5B activity. Subsequent mutation experiments revealed that the increased transcriptional activity was induced by the TATA box and the two p53 binding sites within the section. Further interference with TP53 significantly decreased LTR5Hs transcriptional activity. Chromatin immunoprecipitation (ChIP) and CUT&Tag experiments finally confirmed the direct binding of the p53 protein with the two LTR5Hs p53 binding sites. Overall, the two p53 binding sites in the third section (−263 to 0) of LTR5Hs were revealed to play critical roles in the difference in transcriptional activity among the three subtypes. IMPORTANCE Human endogenous retroviruses (HERVs) were integrated into the human genome in ancient times and have been coevolving with the host. Since the Human Genome Project, HERVs have attracted increasing attention. Many studies have focused on their characterization, evolution, and biological function. In particular, the expression of HERV-K has been associated with many diseases, such as germ cell tumors, neurotoxicity, ovarian cancer, prostate cancer, and melanoma. Indeed, two HML-2-produced proteins, Np9 and Rec, are associated with certain cancers. However, their roles in these disease associations remain unclear. The current work focused on subgroup HML-2 of HERV-K, which is recognized as the most biologically active subgroup, and aimed to explore the mechanistic basis of transcriptional activity. The results revealed that p53 deeply determined the activity of HML-2 LTR5Hs. p53 is a rather important tumor suppressor protein. It can regulate the expression of genes related to cell cycle arrest, organic processes, and apoptosis in response to cellular stress and is critical for the control of homeostasis. Previous ChIP and expression studies of individual genes suggested that p53 sites in HERV LTRs may be part of the p53 transcription program and directly regulate p53 target genes in a species-specific manner. However, the exact function of p53 in the regulation of HERV LTR expression is largely elusive. Our results clearly demonstrated the interaction between LTR5Hs of HML-2 and p53. They are of great significance for the future comprehensive study of the physiological and pathological functions of LTRs of HERVs.
Collapse
|
5
|
Abstract
Human endogenous retroviruses (HERVs) occupy approximately 8% of the human genome. HERVs, transcribed in early embryos, are epigenetically silenced in somatic cells, except under pathological conditions. HERV-K is thought to protect embryos from exogenous viral infection. However, uncontrolled HERV-K expression in somatic cells has been implicated in several diseases. Here, we show that SOX2, which plays a key role in maintaining the pluripotency of stem cells, is critical for HERV-K LTR5Hs. HERV-K undergoes retrotransposition within producer cells in the absence of Env expression. Furthermore, we identified new HERV-K integration sites in long-term culture of induced pluripotent stem cells that express SOX2. These results suggest that the strict dependence of HERV-K on SOX2 has allowed HERV-K to protect early embryos during evolution while limiting the potentially harmful effects of HERV-K retrotransposition on host genome integrity in these early embryos. IMPORTANCE Human endogenous retroviruses (HERVs) account for approximately 8% of the human genome; however, the physiological role of HERV-K remains unknown. This study found that HERV-K LTR5Hs and LTR5B were transactivated by SOX2, which is essential for maintaining and reestablishing pluripotency. HERV-K can undergo retrotransposition within producer cells without env expression, and new integration sites may affect cell proliferation. In induced pluripotent stem cells (iPSCs), genomic impairment due to HERV-K retrotransposition has been identified, but it is a rare event. Considering the retention of SOX2-responsive elements in the HERV-K long terminal repeat (LTR) for over 20 million years, we conclude that HERV-K may play important physiological roles in SOX2-expressing cells.
Collapse
|
6
|
Durnaoglu S, Lee SK, Ahnn J. Human Endogenous Retroviruses as Gene Expression Regulators: Insights from Animal Models into Human Diseases. Mol Cells 2021; 44:861-878. [PMID: 34963103 PMCID: PMC8718366 DOI: 10.14348/molcells.2021.5016] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 11/27/2022] Open
Abstract
The human genome contains many retroviral elements called human endogenous retroviruses (HERVs), resulting from the integration of retroviruses throughout evolution. HERVs once were considered inactive junk because they are not replication-competent, primarily localized in the heterochromatin, and silenced by methylation. But HERVs are now clearly shown to actively regulate gene expression in various physiological and pathological conditions such as developmental processes, immune regulation, cancers, autoimmune diseases, and neurological disorders. Recent studies report that HERVs are activated in patients suffering from coronavirus disease 2019 (COVID-19), the current pandemic caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection. In this review, we describe internal and external factors that influence HERV activities. We also present evidence showing the gene regulatory activity of HERV LTRs (long terminal repeats) in model organisms such as mice, rats, zebrafish, and invertebrate models of worms and flies. Finally, we discuss several molecular and cellular pathways involving various transcription factors and receptors, through which HERVs affect downstream cellular and physiological events such as epigenetic modifications, calcium influx, protein phosphorylation, and cytokine release. Understanding how HERVs participate in various physiological and pathological processes will help develop a strategy to generate effective therapeutic approaches targeting HERVs.
Collapse
Affiliation(s)
- Serpen Durnaoglu
- Department of Life Sciences, College of Natural Sciences, Hanyang University, Seoul 04763, Korea
- Research Institute for Natural Sciences, College of Natural Sciences, Hanyang University, Seoul 04763, Korea
| | - Sun-Kyung Lee
- Department of Life Sciences, College of Natural Sciences, Hanyang University, Seoul 04763, Korea
- Research Institute for Natural Sciences, College of Natural Sciences, Hanyang University, Seoul 04763, Korea
| | - Joohong Ahnn
- Department of Life Sciences, College of Natural Sciences, Hanyang University, Seoul 04763, Korea
- Research Institute for Natural Sciences, College of Natural Sciences, Hanyang University, Seoul 04763, Korea
| |
Collapse
|
7
|
Kitsou K, Iliopoulou M, Spoulou V, Lagiou P, Magiorkinis G. Viral Causality of Human Cancer and Potential Roles of Human Endogenous Retroviruses in the Multi-Omics Era: An Evolutionary Epidemiology Review. Front Oncol 2021; 11:687631. [PMID: 34778024 PMCID: PMC8586426 DOI: 10.3389/fonc.2021.687631] [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: 03/29/2021] [Accepted: 10/12/2021] [Indexed: 12/20/2022] Open
Abstract
Being responsible for almost 12% of cancers worldwide, viruses are among the oldest known and most prevalent oncogenic agents. The quality of the evidence for the in vivo tumorigenic potential of microorganisms varies, thus accordingly, viruses were classified in 4 evidence-based categories by the International Agency for Research on Cancer in 2009. Since then, our understanding of the role of viruses in cancer has significantly improved, firstly due to the emergence of high throughput sequencing technologies that allowed the “brute-force” recovery of unknown viral genomes. At the same time, multi-omics approaches unravelled novel virus-host interactions in stem-cell biology. We now know that viral elements, either exogenous or endogenous, have multiple sometimes conflicting roles in human pathophysiology and the development of cancer. Here we integrate emerging evidence on viral causality in human cancer from basic mechanisms to clinical studies. We analyze viral tumorigenesis under the scope of deep-in-time human-virus evolutionary relationships and critically comment on the evidence through the eyes of clinical epidemiology, firstly by reviewing recognized oncoviruses and their mechanisms of inducing tumorigenesis, and then by examining the potential role of integrated viruses in our genome in the process of carcinogenesis.
Collapse
Affiliation(s)
- Konstantina Kitsou
- Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.,Immunobiology and Vaccinology Research Laboratory, First Department of Peadiatrics, "Aghia Sophia" Children's Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Maria Iliopoulou
- Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Vana Spoulou
- Immunobiology and Vaccinology Research Laboratory, First Department of Peadiatrics, "Aghia Sophia" Children's Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Pagona Lagiou
- Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Gkikas Magiorkinis
- Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| |
Collapse
|
8
|
Grundy EE, Diab N, Chiappinelli KB. Transposable element regulation and expression in cancer. FEBS J 2021; 289:1160-1179. [PMID: 33471418 DOI: 10.1111/febs.15722] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/08/2021] [Accepted: 01/14/2021] [Indexed: 12/11/2022]
Abstract
Approximately 45% of the human genome is composed of transposable elements (TEs). Expression of these elements is tightly regulated during normal development. TEs may be expressed at high levels in embryonic stem cells but are epigenetically silenced in terminally differentiated cells. As part of the global 'epigenetic dysregulation' that cells undergo during transformation from normal to cancer, TEs can lose epigenetic silencing and become transcribed, and, in some cases, active. Here, we summarize recent advances detailing the consequences of TE activation in cancer and describe how these understudied residents of our genome can both aid tumorigenesis and potentially be harnessed for anticancer therapies.
Collapse
Affiliation(s)
- Erin E Grundy
- Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, Washington, DC, USA.,The GW Cancer Center, The George Washington University, Washington, DC, USA.,The Institute for Biomedical Sciences at The George Washington University, Washington, DC, USA
| | - Noor Diab
- Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, Washington, DC, USA.,The GW Cancer Center, The George Washington University, Washington, DC, USA
| | - Katherine B Chiappinelli
- Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, Washington, DC, USA.,The GW Cancer Center, The George Washington University, Washington, DC, USA
| |
Collapse
|
9
|
Wang T, Doucet-O’Hare TT, Henderson L, Abrams RPM, Nath A. Retroviral Elements in Human Evolution and Neural Development. JOURNAL OF EXPERIMENTAL NEUROLOGY 2021; 2:1-9. [PMID: 33693440 PMCID: PMC7943042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Tongguang Wang
- Translational Neuroscience Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Tara T. Doucet-O’Hare
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Lisa Henderson
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Rachel P. M. Abrams
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Avindra Nath
- Translational Neuroscience Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA,Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA,Correspondence should be addressed to Avindra Nath;
| |
Collapse
|
10
|
Gao Y, Yu XF, Chen T. Human endogenous retroviruses in cancer: Expression, regulation and function. Oncol Lett 2020; 21:121. [PMID: 33552242 PMCID: PMC7798031 DOI: 10.3892/ol.2020.12382] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 11/27/2020] [Indexed: 12/16/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are the remnants of ancient retroviruses that infected human germline cells and became integrated into the human genome millions of years ago. Although most of these sequences are incomplete and silent, several potential pathological roles of HERVs have been observed in numerous diseases, such as multiple sclerosis and rheumatoid arthritis, and especially cancer, including breast cancer and pancreatic carcinoma. The present review investigates the expression signatures and complex regulatory mechanisms of HERVs in cancer. The long terminal repeats-driven transcriptional initiation of HERVs are regulated by transcription factors (such as Sp3) and epigenetic modifications (such as DNA methylation), and are influenced by environmental factors (such as ultraviolet radiation). In addition, this review focuses on the dual opposing effects of HERVs in cancer. HERVs can suppress cancer via immune activation; however, they can also promote cancer. HERV env gene serves a prime role in promoting carcinogenesis in certain malignant tumors, including breast cancer, pancreatic cancer, germ cell tumors, leukemia and Kaposi's sarcoma. Also, HERV ENV proteins can promote cancer via immune suppression. Targeting ENV proteins is a potential future antitumor treatment modality.
Collapse
Affiliation(s)
- Yuan Gao
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zheijang 310009, P.R. China
| | - Xiao-Fang Yu
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zheijang 310009, P.R. China
| | - Ting Chen
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zheijang 310009, P.R. China
| |
Collapse
|
11
|
Human Endogenous Retrovirus K Rec forms a Regulatory Loop with MITF that Opposes the Progression of Melanoma to an Invasive Stage. Viruses 2020; 12:v12111303. [PMID: 33202765 PMCID: PMC7696977 DOI: 10.3390/v12111303] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 11/10/2020] [Accepted: 11/11/2020] [Indexed: 12/19/2022] Open
Abstract
The HML2 subfamily of HERV-K (henceforth HERV-K) represents the most recently endogenized retrovirus in the human genome. While the products of certain HERV-K genomic copies are expressed in normal tissues, they are upregulated in several pathological conditions, including various tumors. It remains unclear whether HERV-K(HML2)-encoded products overexpressed in cancer contribute to disease progression or are merely by-products of tumorigenesis. Here, we focus on the regulatory activities of the Long Terminal Repeats (LTR5_Hs) of HERV-K and the potential role of the HERV-K-encoded Rec in melanoma. Our regulatory genomics analysis of LTR5_Hs loci indicates that Melanocyte Inducing Transcription Factor (MITF) (also known as binds to a canonical E-box motif (CA(C/T)GTG) within these elements in proliferative type of melanoma, and that depletion of MITF results in reduced HERV-K expression. In turn, experimentally depleting Rec in a proliferative melanoma cell line leads to lower mRNA levels of MITF and its predicted target genes. Furthermore, Rec knockdown leads to an upregulation of epithelial-to-mesenchymal associated genes and an enhanced invasion phenotype of proliferative melanoma cells. Together these results suggest the existence of a regulatory loop between MITF and Rec that may modulate the transition from proliferative to invasive stages of melanoma. Because HERV-K(HML2) elements are restricted to hominoid primates, these findings might explain certain species-specific features of melanoma progression and point to some limitations of animal models in melanoma studies.
Collapse
|
12
|
Edginton-White B, Cauchy P, Assi SA, Hartmann S, Riggs AG, Mathas S, Cockerill PN, Bonifer C. Global long terminal repeat activation participates in establishing the unique gene expression programme of classical Hodgkin lymphoma. Leukemia 2018; 33:1463-1474. [PMID: 30546079 PMCID: PMC6558280 DOI: 10.1038/s41375-018-0311-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 10/18/2018] [Accepted: 10/29/2018] [Indexed: 12/13/2022]
Abstract
Long terminal repeat (LTR) elements are wide-spread in the human genome and have the potential to act as promoters and enhancers. Their expression is therefore under tight epigenetic control. We previously reported in classical Hodgkin Lymphoma (cHL) that a member of the THE1B class of LTR elements acted as a promoter for the proto-oncogene and growth factor receptor gene CSF1R and that expression of this gene is required for cHL tumour survival. However, to which extent and how such elements participate in globally shaping the unique cHL gene expression programme is unknown. To address this question we mapped the genome-wide activation of THE1-LTRs in cHL cells using a targeted next generation sequencing approach (RACE-Seq). Integration of these data with global gene expression data from cHL and control B cell lines showed a unique pattern of LTR activation impacting on gene expression, including genes associated with the cHL phenotype. We also show that global LTR activation is induced by strong inflammatory stimuli. Together these results demonstrate that LTR activation provides an additional layer of gene deregulation in classical Hodgkin lymphoma and highlight the potential impact of genome-wide LTR activation in other inflammatory diseases.
Collapse
Affiliation(s)
- Benjamin Edginton-White
- Institute for Cancer and Genomic Sciences, University of Birmingham, College of Medical and Dental Sciences, Birmingham, B152TT, UK
| | - Pierre Cauchy
- Institute for Cancer and Genomic Sciences, University of Birmingham, College of Medical and Dental Sciences, Birmingham, B152TT, UK.,Department of Cellular and Molecular Immunology, Max Planck Institute for Immunobiology and Epigenetics, 79108, Freiburg, Germany
| | - Salam A Assi
- Institute for Cancer and Genomic Sciences, University of Birmingham, College of Medical and Dental Sciences, Birmingham, B152TT, UK
| | - Sylvia Hartmann
- Senckenberg Institute of Pathology, University Hospital, 60590, Frankfurt, Germany
| | - Arthur G Riggs
- Beckman Research Institute of City of Hope Medical Center, Duarte, CA, 91010, USA
| | - Stephan Mathas
- Max-Delbrück-Center for Molecular Medicine, 13125, Berlin, Germany.,Hematology, Oncology, and Tumor Immunology, Charité - Universitätsmedizin Berlin, 12200, Berlin, Germany
| | - Peter N Cockerill
- Institute for Cancer and Genomic Sciences, University of Birmingham, College of Medical and Dental Sciences, Birmingham, B152TT, UK
| | - Constanze Bonifer
- Institute for Cancer and Genomic Sciences, University of Birmingham, College of Medical and Dental Sciences, Birmingham, B152TT, UK.
| |
Collapse
|
13
|
Attermann A, Bjerregaard AM, Saini S, Grønbæk K, Hadrup S. Human endogenous retroviruses and their implication for immunotherapeutics of cancer. Ann Oncol 2018; 29:2183-2191. [DOI: 10.1093/annonc/mdy413] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
14
|
Garcia-Montojo M, Doucet-O'Hare T, Henderson L, Nath A. Human endogenous retrovirus-K (HML-2): a comprehensive review. Crit Rev Microbiol 2018; 44:715-738. [PMID: 30318978 DOI: 10.1080/1040841x.2018.1501345] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The human genome contains a large number of retroviral elements acquired over the process of evolution, some of which are specific to primates. However, as many of these are defective or silenced through epigenetic changes, they were historically considered "junk DNA" and their potential role in human physiology or pathological circumstances have been poorly studied. The most recently acquired, human endogenous retrovirus-K (HERV-K), has multiple copies in the human genome and some of them have complete open reading frames that are transcribed and translated, especially in early embryogenesis. Phylogenetically, HERV-K is considered a supergroup of viruses. One of the subtypes, termed HML-2, seems to be the most active and hence, it is the best studied. Aberrant expression of HML-2 in adult tissues has been associated with certain types of cancer and with neurodegenerative diseases. This review discusses the discovery of these viruses, their classification, structure, regulation and potential for replication, physiological roles, and their involvement in disease pathogenesis. Finally, it presents different therapeutic approaches being considered to target these viruses.
Collapse
Affiliation(s)
- Marta Garcia-Montojo
- a Section of Infections of the Nervous System , National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda , MD , USA
| | - Tara Doucet-O'Hare
- a Section of Infections of the Nervous System , National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda , MD , USA
| | - Lisa Henderson
- a Section of Infections of the Nervous System , National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda , MD , USA
| | - Avindra Nath
- a Section of Infections of the Nervous System , National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda , MD , USA
| |
Collapse
|
15
|
Grandi N, Tramontano E. HERV Envelope Proteins: Physiological Role and Pathogenic Potential in Cancer and Autoimmunity. Front Microbiol 2018; 9:462. [PMID: 29593697 PMCID: PMC5861771 DOI: 10.3389/fmicb.2018.00462] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 02/27/2018] [Indexed: 12/29/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are relics of ancient infections accounting for about the 8% of our genome. Despite their persistence in human DNA led to the accumulation of mutations, HERVs are still contributing to the human transcriptome, and a growing number of findings suggests that their expression products may have a role in various diseases. Among HERV products, the envelope proteins (Env) are currently highly investigated for their pathogenic properties, which could likely be participating to several disorders with complex etiology, particularly in the contexts of autoimmunity and cancer. In fact, HERV Env proteins have been shown, on the one side, to trigger both innate and adaptive immunity, prompting inflammatory, cytotoxic and apoptotic reactions; and, on the other side, to prevent the immune response activation, presenting immunosuppressive properties and acting as immune downregulators. In addition, HERV Env proteins have been shown to induce abnormal cell-cell fusion, possibly contributing to tumor development and metastasizing processes. Remarkably, even highly defective HERV env genes and alternative env splicing variants can provide further mechanisms of pathogenesis. A well-known example is the HERV-K(HML2) env gene that, depending on the presence or the absence of a 292-bp deletion, can originate two proteins of different length (Np9 and Rec) proposed to have oncogenic properties. The understanding of their involvement in complex pathological disorders made HERV Env proteins potential targets for therapeutic interventions. Of note, a monoclonal antibody directed against a HERV-W Env is currently under clinical trial as therapeutic approach for multiple sclerosis, representing the first HERV-based treatment. The present review will focus on the current knowledge of the HERV Env expression, summarizing its role in human physiology and its possible pathogenic effects in various cancer and autoimmune disorders. It moreover analyzes HERV Env possible exploitation for the development of innovative therapeutic strategies.
Collapse
Affiliation(s)
- Nicole Grandi
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Enzo Tramontano
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Cagliari, Italy
| |
Collapse
|
16
|
Bourneuf E. The MeLiM Minipig: An Original Spontaneous Model to Explore Cutaneous Melanoma Genetic Basis. Front Genet 2017; 8:146. [PMID: 29081790 PMCID: PMC5645500 DOI: 10.3389/fgene.2017.00146] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 09/25/2017] [Indexed: 12/19/2022] Open
Abstract
Melanoma is the deadliest skin cancer and is a major public health concern with a growing incidence worldwide. As for other complex diseases, animal models are needed in order to better understand the mechanisms leading to pathology, identify potential biomarkers to be used in the clinics, and eventually molecular targets for therapeutic solutions. Cutaneous melanoma, arising from skin melanocytes, is mainly caused by environmental factors such as UV radiation; however a significant genetic component participates in the etiology of the disease. The pig is a recognized model for spontaneous development of melanoma with features similar to the human ones, followed by a complete regression and a vitiligo-like depigmentation. Three different pig models (MeLiM, Sinclair, and MMS-Troll) have been maintained through the last decades, and different genetic studies have evidenced a complex inheritance of the disease. As in humans, pigmentation seems to play a prominent role, notably through MC1R and MITF signaling. Conversely, cell cycle genes as CDKN2A and CDK4 have been excluded as predisposing for melanoma in MeLiM. So far, only sparse studies have focused on somatic changes occurring during oncogenesis, and have revealed major cytological changes and a potential dysfunction of the telomere maintenance system. Finally, the spontaneous tumor progression and regression occurring in these models could shed light on the interplay between endogenous retroviruses, melanomagenesis, and adaptive immune response.
Collapse
Affiliation(s)
- Emmanuelle Bourneuf
- LREG, CEA, Université Paris-Saclay, Jouy-en-Josas, France.,GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| |
Collapse
|
17
|
de Mulder M, SenGupta D, Deeks SG, Martin JN, Pilcher CD, Hecht FM, Sacha JB, Nixon DF, Michaud HA. Anti-HERV-K (HML-2) capsid antibody responses in HIV elite controllers. Retrovirology 2017; 14:41. [PMID: 28830571 PMCID: PMC5568399 DOI: 10.1186/s12977-017-0365-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 08/13/2017] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Human endogenous retroviruses (HERVs) comprise approximately 8% of the human genome and while the majority are transcriptionally silent, the most recently integrated HERV, HERV-K (HML-2), remains active. During HIV infection, HERV-K (HML-2) specific mRNA transcripts and viral proteins can be detected. In this study, we aimed to understand the antibody response against HERV-K (HML-2) Gag in the context of HIV-1 infection. RESULTS We developed an ELISA assay using either recombinant protein or 164 redundant "15mer" HERV-K (HML-2) Gag peptides to test sera for antibody reactivity. We identified a total of eight potential HERV-K (HML-2) Gag immunogenic domains: two on the matrix (peptides 16 and 31), one on p15 (peptide 85), three on the capsid (peptides 81, 97 and 117), one on the nucleocapsid (peptide 137) and one on the QP1 protein (peptide 157). Four epitopes (peptides 16, 31, 85 and 137) were highly immunogenic. No significant differences in antibody responses were found between HIV infected participants (n = 40) and uninfected donors (n = 40) for 6 out of the 8 epitopes tested. The antibody response against nucleocapsid (peptide 137) was significantly lower (p < 0.001), and the response to QP1 (peptide 157) significantly higher (p < 0.05) in HIV-infected adults compared to uninfected individuals. Among those with HIV infection, the level of response against p15 protein (peptide 85) was significantly lower in untreated individuals controlling HIV ("elite" controllers) compared to untreated non-controllers (p < 0.05) and uninfected donors (p < 0.05). In contrast, the response against the capsid protein (epitopes 81 and 117) was significantly higher in controllers compared to uninfected donors (p < 0.001 and <0.05 respectively) and non-controllers (p < 0.01 and <0.05). Peripheral blood mononuclear cells (PBMCs) from study participants were tested for responses against HERV-K (HML-2) capsid recombinant peptide in gamma interferon (IFN-γ) enzyme immunospot (Elispot) assays. We found that the HERV-K (HML-2) Gag antibody and T cell response by Elispot were significantly correlated. CONCLUSIONS HIV elite controllers had a strong cellular and antibody response against HERV-K (HML-2) Gag directed mainly against the Capsid region. Collectively, these data suggest that anti-HERV-K (HML-2) antibodies targeting capsid could have an immunoprotective effect in HIV infection.
Collapse
Affiliation(s)
- Miguel de Mulder
- Department of Microbiology, Immunology, and Tropical Medicine, The George Washington University, Ross Hall 604, 2300 Eye St. NW, Washington, DC 20037 USA
| | - Devi SenGupta
- Gilead Sciences Inc., Foster City, CA USA
- Division of Experimental Medicine, Department of Medicine, University of California, San Francisco, San Francisco, CA USA
| | - Steven G. Deeks
- HIV/AIDS Program, Department of Medicine, University of California, San Francisco, San Francisco, CA USA
| | - Jeffrey N. Martin
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA USA
| | - Christopher D. Pilcher
- HIV/AIDS Program, Department of Medicine, University of California, San Francisco, San Francisco, CA USA
| | - Frederick M. Hecht
- HIV/AIDS Program, Department of Medicine, University of California, San Francisco, San Francisco, CA USA
| | - Jonah B. Sacha
- Division of Pathobiology and Immunology, Oregon Health and Science University, Portland, CA USA
| | - Douglas F. Nixon
- Department of Microbiology, Immunology, and Tropical Medicine, The George Washington University, Ross Hall 604, 2300 Eye St. NW, Washington, DC 20037 USA
- Division of Experimental Medicine, Department of Medicine, University of California, San Francisco, San Francisco, CA USA
| | - Henri-Alexandre Michaud
- Division of Experimental Medicine, Department of Medicine, University of California, San Francisco, San Francisco, CA USA
- Equipe Immunité et Cancer, Institut de Recherche en Cancérlogie de Montpellier, Montpellier, France
| |
Collapse
|
18
|
Li M, Radvanyi L, Yin B, Rycaj K, Li J, Chivukula R, Lin K, Lu Y, Shen J, Chang DZ, Li D, Johanning GL, Wang-Johanning F. Downregulation of Human Endogenous Retrovirus Type K (HERV-K) Viral env RNA in Pancreatic Cancer Cells Decreases Cell Proliferation and Tumor Growth. Clin Cancer Res 2017; 23:5892-5911. [PMID: 28679769 DOI: 10.1158/1078-0432.ccr-17-0001] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 05/09/2017] [Accepted: 06/29/2017] [Indexed: 12/23/2022]
Abstract
Purpose: We investigated the role of the human endogenous retrovirus type K (HERV-K) envelope (env) gene in pancreatic cancer.Experimental Design: shRNA was employed to knockdown (KD) the expression of HERV-K in pancreatic cancer cells.Results: HERV-K env expression was detected in seven pancreatic cancer cell lines and in 80% of pancreatic cancer patient biopsies, but not in two normal pancreatic cell lines or uninvolved normal tissues. A new HERV-K splice variant was discovered in several pancreatic cancer cell lines. Reverse transcriptase activity and virus-like particles were observed in culture media supernatant obtained from Panc-1 and Panc-2 cells. HERV-K viral RNA levels and anti-HERV-K antibody titers were significantly higher in pancreatic cancer patient sera (N = 106) than in normal donor sera (N = 40). Importantly, the in vitro and in vivo growth rates of three pancreatic cancer cell lines were significantly reduced after HERV-K KD by shRNA targeting HERV-K env, and there was reduced metastasis to lung after treatment. RNA-Seq results revealed changes in gene expression after HERV-K env KD, including RAS and TP53. Furthermore, downregulation of HERV-K Env protein expression by shRNA also resulted in decreased expression of RAS, p-ERK, p-RSK, and p-AKT in several pancreatic cancer cells or tumors.Conclusions: These results demonstrate that HERV-K influences signal transduction via the RAS-ERK-RSK pathway in pancreatic cancer. Our data highlight the potentially important role of HERV-K in tumorigenesis and progression of pancreatic cancer, and indicate that HERV-K viral proteins may be attractive biomarkers and/or tumor-associated antigens, as well as potentially useful targets for detection, diagnosis, and immunotherapy of pancreatic cancer. Clin Cancer Res; 23(19); 5892-911. ©2017 AACR.
Collapse
Affiliation(s)
- Ming Li
- Viral Oncology Program, Center for Cancer and Metabolism, SRI International, Menlo Park, California
| | - Laszlo Radvanyi
- EMD Serono Research and Development Institute, Billerica, Massachusetts
| | - Bingnan Yin
- Department of Inflammation and Epigenetics, Methodist Research Institute, Houston, Texas
| | | | - Jia Li
- Viral Oncology Program, Center for Cancer and Metabolism, SRI International, Menlo Park, California
| | - Raghavender Chivukula
- Viral Oncology Program, Center for Cancer and Metabolism, SRI International, Menlo Park, California
| | - Kevin Lin
- Department of Epigenetics and Molecular Carcinogenesis, Science Park, the University of Texas MD Anderson Cancer Center, Smithville, Texas
| | - Yue Lu
- Department of Epigenetics and Molecular Carcinogenesis, Science Park, the University of Texas MD Anderson Cancer Center, Smithville, Texas
| | - JianJun Shen
- Department of Epigenetics and Molecular Carcinogenesis, Science Park, the University of Texas MD Anderson Cancer Center, Smithville, Texas
| | - David Z Chang
- Virginia Oncology Associates, Newport News, Virginia
| | - Donghui Li
- Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Gary L Johanning
- Viral Oncology Program, Center for Cancer and Metabolism, SRI International, Menlo Park, California
| | - Feng Wang-Johanning
- Viral Oncology Program, Center for Cancer and Metabolism, SRI International, Menlo Park, California.
| |
Collapse
|
19
|
Lemaître C, Tsang J, Bireau C, Heidmann T, Dewannieux M. A human endogenous retrovirus-derived gene that can contribute to oncogenesis by activating the ERK pathway and inducing migration and invasion. PLoS Pathog 2017. [PMID: 28651004 PMCID: PMC5501692 DOI: 10.1371/journal.ppat.1006451] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Endogenous retroviruses are cellular genes of retroviral origin captured by their host during the course of evolution and represent around 8% of the human genome. Although most are defective and transcriptionally silenced, some are still able to generate retroviral-like particles and proteins. Among these, the HERV-K(HML2) family is remarkable since its members have amplified relatively recently and many of them still have full length coding genes. Furthermore, they are induced in cancers, especially in melanoma, breast cancer and germ cell tumours, where viral particles, as well as the envelope protein (Env), can be detected. Here we show that HERV-K(HML2) Env per se has oncogenic properties. Its expression in a non-tumourigenic human breast epithelial cell line induces epithelial to mesenchymal transition (EMT), often associated with tumour aggressiveness and metastasis. In our model, this is typified by key modifications in a set of molecular markers, changes in cell morphology and enhanced cell motility. Remarkably, microarrays performed in 293T cells reveal that HERV-K(HML2) Env is a strong inducer of several transcription factors, namely ETV4, ETV5 and EGR1, which are downstream effectors of the MAPK ERK1/2 and are associated with cellular transformation. We demonstrate that HERV-K(HML2) Env effectively activates the ERK1/2 pathway in our experimental setting and that this activation depends on the Env cytoplasmic tail. In addition, this phenomenon is very specific, being absent with every other retroviral Env tested, except for Jaagsiekte Sheep Retrovirus (JSRV) Env, which is already known to have transforming properties in vivo. Though HERV-K Env is not directly transforming by itself, the newly discovered properties of this protein may contribute to oncogenesis. Nearly half the DNA of mammals consists of reitarated, selfish elements that can move and amplify within the genome. With time, some of these elements are recruited by the host and the proteins they encode are used to fulfill physiological functions, whereas other elements have conserved some of their pathological properties and contribute to the development of diseases. The human HERV-K(HML2) elements originated from an ancestral infection of the primate germline by an infectious retrovirus that has been maintained and amplified in the human lineage. It is associated with several pathologies in modern humans, in particular cancer of the breast, germline and skin. We show that the HERV-K(HML2) envelope protein is able to activate a major cellular signalling pathway often involved in human cancers, and that its expression promotes a series of cellular changes that are characteristic of cancer development. Altogether, this study indicates that the expression of HERV-K(HML2) elements is not only a marker of cancer, but can also directly participate to tumourigenesis via the newly discovered oncogenic properties carried by the envelope protein.
Collapse
Affiliation(s)
- Cécile Lemaître
- CNRS, UMR 9196, Institut Gustave Roussy, Villejuif, France
- Université Paris-Sud, Orsay, France
- Université Paris Denis Diderot, Sorbonne Paris-Cité, Paris, France
| | - Jhen Tsang
- CNRS, UMR 9196, Institut Gustave Roussy, Villejuif, France
- Université Paris-Sud, Orsay, France
| | - Caroline Bireau
- CNRS, UMR 9196, Institut Gustave Roussy, Villejuif, France
- Université Paris-Sud, Orsay, France
| | - Thierry Heidmann
- CNRS, UMR 9196, Institut Gustave Roussy, Villejuif, France
- Université Paris-Sud, Orsay, France
- * E-mail: (MD); (TH)
| | - Marie Dewannieux
- CNRS, UMR 9196, Institut Gustave Roussy, Villejuif, France
- Université Paris-Sud, Orsay, France
- * E-mail: (MD); (TH)
| |
Collapse
|
20
|
EnHERV: Enrichment analysis of specific human endogenous retrovirus patterns and their neighboring genes. PLoS One 2017; 12:e0177119. [PMID: 28472109 PMCID: PMC5417679 DOI: 10.1371/journal.pone.0177119] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 04/21/2017] [Indexed: 12/24/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are flanked by long terminal repeats (LTRs), which contain the regulation part of the retrovirus. Remaining HERVs constitute 7% to 8% of the present day human genome, and most have been identified as solo LTRs. The HERV sequences have been associated with several molecular functions as well as certain diseases in human, but their roles in human diseases are yet to be established. We designed EnHERV to make accessible the identified endogenous retrovirus repetitive sequences from Repbase Update (a database of eukaryotic repetitive elements) that are present in the human genome. Defragmentation process was done to improve the RepeatMasker annotation output. The defragmented elements were used as core database in EnHERV. EnHERV is available at http://sysbio.chula.ac.th/enherv and can be searched using either gene lists of user interest or HERV characteristics. Besides the search function, EnHERV also provides an enrichment analysis function that allows users to perform enrichment analysis between selected HERV characteristics and user-input gene lists, especially genes with the expression profile of a certain disease. EnHERV will facilitate exploratory studies of specific HERV characteristics that control gene expression patterns related to various disease conditions. Here we analyzed 25 selected HERV groups/names from all four HERV superfamilies, using the sense and anti-sense directions of the HERV and gene expression profiles from 49 specific tissue and disease conditions. We found that intragenic HERVs were associated with down-regulated genes in most cancer conditions and in psoriatic skin tissues and associated with up-regulated genes in immune cells particularly from systemic lupus erythematosus (SLE) patients. EnHERV allowed the analysis of how different types of LTRs were differentially associated with specific gene expression profiles in particular disease conditions for further studies into their mechanisms and functions.
Collapse
|
21
|
Gonzalez-Cao M, Iduma P, Karachaliou N, Santarpia M, Blanco J, Rosell R. Human endogenous retroviruses and cancer. Cancer Biol Med 2016; 13:483-488. [PMID: 28154780 PMCID: PMC5250606 DOI: 10.20892/j.issn.2095-3941.2016.0080] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Human endogenous retroviruses (HERVs) are retroviruses that infected human genome millions of years ago and have persisted throughout human evolution. About 8% of our genome is composed of HERVs, most of which are nonfunctional because of epigenetic control or deactivating mutations. However, a correlation between HERVs and human cancer has been described and many tumors, such as melanoma, breast cancer, germ cell tumors, renal cancer or ovarian cancer, express HERV proteins, mainly HERV-K (HML6) and HERV-K (HML2). Although the causative role of HERVs in cancer is controversial, data from animal models demonstrated that endogenous retroviruses are potentially oncogenic. HERV protein expression in human cells generates an immune response by activating innate and adaptive immunities. Some HERV-derived peptides have antigenic properties. For example, HERV-K (HML-6) encodes the HER-K MEL peptide recognized by CD8+ lymphocytes. In addition, HERVs are two-edged immunomodulators. HERVs show immunosuppressive activity. The presence of genomic retroviral elements in host-cell cytosol may activate an interferon type I response. Therefore, targeting HERVs through cellular vaccines or immunomodulatory drugs combined with checkpoint inhibitors is attracting interest because they could be active in human tumors.
Collapse
Affiliation(s)
- María Gonzalez-Cao
- Translational Cancer Research Unit, Instituto Oncológico Dr Rosell, Quirón Dexeus University Hospital, Barcelona 08028, Spain
| | - Paola Iduma
- AIDS Research Institute, Hospital Universitari Germans Trias i Pujol, Badalona 08028, Spain
| | - Niki Karachaliou
- Translational Cancer Research Unit, Instituto Oncológico Dr Rosell, Quirón Dexeus University Hospital, Barcelona 08028, Spain
| | - Mariacarmela Santarpia
- Medical Oncology Unit, Human Pathology Department, University of Messina, Messina, 98122, Italy
| | - Julià Blanco
- AIDS Research Institute, Hospital Universitari Germans Trias i Pujol, Badalona 08028, Spain; UVIC-UCC, Catalunya 08500, Spain
| | - Rafael Rosell
- Translational Cancer Research Unit, Instituto Oncológico Dr Rosell, Quirón Dexeus University Hospital, Barcelona 08028, Spain; Cancer Biology & Precision Medicine Program, Catalan Institute of Oncology, Germans Trias I Pujol Health Sciences Institute and Hospital, Campus Can Ruti, Badalona, 08916, Spain; Fundación Molecular Oncology Research, Barcelona 08028, Spain
| |
Collapse
|
22
|
Kim YJ, Ahn K, Gim JA, Oh MH, Han K, Kim HS. Gene structure variation in segmental duplication block C of human chromosome 7q 11.23 during primate evolution. Gene 2015. [PMID: 26196062 DOI: 10.1016/j.gene.2015.07.060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Segmental duplication, or low-copy repeat (LCR) event, occurs during primate evolution and is an important source of genomic diversity, including gain or loss of gene function. The human chromosome 7q 11.23 is related to the William-Beuren syndrome and contains large region-specific LCRs composed of blocks A, B, and C that have different copy numbers in humans and different primates. We analyzed the structure of POM121, NSUN5, FKBP6, and TRIM50 genes in the LCRs of block C. Based on computational analysis, POM121B created by a segmental duplication acquired a new exonic region, whereas NSUN5B (NSUN5C) showed structural variation by integration of HERV-K LTR after duplication from the original NSUN5 gene. The TRIM50 gene originally consists of seven exons, whereas the duplicated TRIM73 and TRIM74 genes present five exons because of homologous recombination-mediated deletion. In addition, independent duplication events of the FKBP6 gene generated two pseudogenes at different genomic locations. In summary, these clustered genes are created by segmental duplication, indicating that they show dynamic evolutionary events, leading to structure variation in the primate genome.
Collapse
Affiliation(s)
- Yun-Ji Kim
- Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330-714, Republic of Korea; DKU-Theragen Institute for NGS Analysis (DTiNa), Cheonan 330-714, Republic of Korea
| | - Kung Ahn
- TBI, Theragen BiO Institute, TheragenEtex, Suwon 443-270, Republic of Korea
| | - Jeong-An Gim
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea
| | - Man Hwan Oh
- Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330-714, Republic of Korea
| | - Kyudong Han
- Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330-714, Republic of Korea; DKU-Theragen Institute for NGS Analysis (DTiNa), Cheonan 330-714, Republic of Korea
| | - Heui-Soo Kim
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea.
| |
Collapse
|
23
|
Nadeau MJ, Manghera M, Douville RN. Inside the Envelope: Endogenous Retrovirus-K Env as a Biomarker and Therapeutic Target. Front Microbiol 2015; 6:1244. [PMID: 26617584 PMCID: PMC4643131 DOI: 10.3389/fmicb.2015.01244] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 10/26/2015] [Indexed: 11/27/2022] Open
Abstract
Due to multiple ancestral human retroviral germ cell infections, the modern human genome is strewn with relics of these infections, termed endogenous retroviruses (ERVs). ERV expression has been silenced due to negative selective pressures and genetic phenomena such as mutations and epigenetic silencing. Nonetheless, select ERVs have retained the capacity to be damaging to their host when reawakened. Much of the current research on the ERVK Env protein strongly suggests a causal or contributive role in the pathogenesis of various cancers, autoimmune and infectious diseases. Additionally, there is a small body of research suggesting that ERVK Env has been domesticated for use in placental development, akin to the ERVW syncytin. Though much is left to ascertain, the innate immune response to ERVK Env expression has been partially characterized and appears to be due to a region located in the transmembrane domain of the Env protein. In this review, we aim to highlight ERVK Env as a biomarker for inflammatory conditions and explore its use as a future therapeutic target for cancers, HIV infection and neurological disease.
Collapse
Affiliation(s)
- Marie-Josée Nadeau
- Douville Lab, Department of Biology, University of Winnipeg Winnipeg, MB, Canada
| | - Mamneet Manghera
- Douville Lab, Department of Biology, University of Winnipeg Winnipeg, MB, Canada ; Department of Immunology, University of Manitoba Winnipeg, MB, Canada
| | - Renée N Douville
- Douville Lab, Department of Biology, University of Winnipeg Winnipeg, MB, Canada ; Department of Immunology, University of Manitoba Winnipeg, MB, Canada
| |
Collapse
|
24
|
Suntsova M, Garazha A, Ivanova A, Kaminsky D, Zhavoronkov A, Buzdin A. Molecular functions of human endogenous retroviruses in health and disease. Cell Mol Life Sci 2015; 72:3653-75. [PMID: 26082181 PMCID: PMC11113533 DOI: 10.1007/s00018-015-1947-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 05/29/2015] [Accepted: 06/03/2015] [Indexed: 12/13/2022]
Abstract
Human endogenous retroviruses (HERVs) and related genetic elements form 504 distinct families and occupy ~8% of human genome. Recent success of high-throughput experimental technologies facilitated understanding functional impact of HERVs for molecular machinery of human cells. HERVs encode active retroviral proteins, which may exert important physiological functions in the body, but also may be involved in the progression of cancer and numerous human autoimmune, neurological and infectious diseases. The spectrum of related malignancies includes, but not limits to, multiple sclerosis, psoriasis, lupus, schizophrenia, multiple cancer types and HIV. In addition, HERVs regulate expression of the neighboring host genes and modify genomic regulatory landscape, e.g., by providing regulatory modules like transcription factor binding sites (TFBS). Indeed, recent bioinformatic profiling identified ~110,000 regulatory active HERV elements, which formed at least ~320,000 human TFBS. These and other peculiarities of HERVs might have played an important role in human evolution and speciation. In this paper, we focus on the current progress in understanding of normal and pathological molecular niches of HERVs, on their implications in human evolution, normal physiology and disease. We also review the available databases dealing with various aspects of HERV genetics.
Collapse
Affiliation(s)
- Maria Suntsova
- Group for Genomic Regulation of Cell Signaling Systems, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
- Laboratory of Bioinformatics, D. Rogachyov Federal Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, 117198, Russia.
| | - Andrew Garazha
- Group for Genomic Regulation of Cell Signaling Systems, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
- Laboratory of Bioinformatics, D. Rogachyov Federal Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, 117198, Russia.
| | - Alena Ivanova
- Group for Genomic Regulation of Cell Signaling Systems, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
- Pathway Pharmaceuticals, Wan Chai, Hong Kong, Hong Kong SAR.
| | - Dmitry Kaminsky
- Pathway Pharmaceuticals, Wan Chai, Hong Kong, Hong Kong SAR.
| | - Alex Zhavoronkov
- Pathway Pharmaceuticals, Wan Chai, Hong Kong, Hong Kong SAR.
- Department of Translational and Regenerative Medicine, Moscow Institute of Physics and Technology, 9 Institutskiy per., Dolgoprudny, Moscow, 141700, Russia.
| | - Anton Buzdin
- Group for Genomic Regulation of Cell Signaling Systems, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
- Pathway Pharmaceuticals, Wan Chai, Hong Kong, Hong Kong SAR.
- National Research Centre "Kurchatov Institute", Centre for Convergence of Nano-, Bio-, Information and Cognitive Sciences and Technologies, 1, Akademika Kurchatova sq., Moscow, 123182, Russia.
| |
Collapse
|
25
|
DiVito KA, Trabosh VA, Chen YS, Simbulan-Rosenthal CM, Rosenthal DS. Inhibitor of differentiation-4 (Id4) stimulates pigmentation in melanoma leading to histiocyte infiltration. Exp Dermatol 2015; 24:101-7. [DOI: 10.1111/exd.12582] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2014] [Indexed: 11/27/2022]
Affiliation(s)
- Kyle A. DiVito
- Department of Biochemistry & Molecular Biology; Georgetown University School of Medicine; Washington DC USA
| | - Valerie A. Trabosh
- Department of Biochemistry & Molecular Biology; Georgetown University School of Medicine; Washington DC USA
| | - You-Shin Chen
- Department of Biochemistry & Molecular Biology; Georgetown University School of Medicine; Washington DC USA
| | | | - Dean S. Rosenthal
- Department of Biochemistry & Molecular Biology; Georgetown University School of Medicine; Washington DC USA
| |
Collapse
|
26
|
Cancer subclonal genetic architecture as a key to personalized medicine. Neoplasia 2014; 15:1410-20. [PMID: 24403863 DOI: 10.1593/neo.131972] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 12/03/2013] [Accepted: 12/03/2013] [Indexed: 02/08/2023] Open
Abstract
The future of personalized oncological therapy will likely rely on evidence-based medicine to integrate all of the available evidence to delineate the most efficacious treatment option for the patient. To undertake evidence-based medicine through use of targeted therapy regimens, identification of the specific underlying causative mutation(s) driving growth and progression of a patient's tumor is imperative. Although molecular subtyping is important for planning and treatment, intraclonal genetic diversity has been recently highlighted as having significant implications for biopsy-based prognosis. Overall, delineation of the clonal architecture of a patient's cancer and how this will impact on the selection of the most efficacious therapy remain a topic of intense interest.
Collapse
|
27
|
Emmer A, Staege MS, Kornhuber ME. The retrovirus/superantigen hypothesis of multiple sclerosis. Cell Mol Neurobiol 2014; 34:1087-96. [PMID: 25138639 DOI: 10.1007/s10571-014-0100-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 08/09/2014] [Indexed: 12/21/2022]
Abstract
The pathogenesis of multiple sclerosis (MS) is as yet unknown. Commonly, MS is assumed to be due to an autoimmune inflammation of the central nervous system (CNS). Neurodegeneration is regarded to be a secondary reaction. This concept is increasingly being challenged. Human endogenous retroviruses (HERV) that could be locally activated in the CNS have been proposed as an alternative concept. HERV-encoded envelope proteins (env) can act as strong immune stimulators (superantigens). Thus, slow disease progression following neurodegeneration might be induced by re-activation of HERV expression directly, while relapses in parallel to inflammation might be secondary to the expression of HERV-encoded superantigens. It has been shown previously that T-cell superantigens are capable to induce a cellular inflammatory reaction in the CNS of experimental animals similar to that in MS. Furthermore, B-cell superantigens have been shown to activate blood leucocytes in vitro to produce immunoglobulin in an oligoclonal manner. It remains to be established, whether the outlined hypothesis accords with all known features of MS. Furthermore, anti-HERV agents may be taken into consideration to enrich and improve MS therapy.
Collapse
Affiliation(s)
- Alexander Emmer
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany,
| | | | | |
Collapse
|
28
|
Manghera M, Ferguson J, Douville R. Endogenous Retrovirus-K and Nervous System Diseases. Curr Neurol Neurosci Rep 2014; 14:488. [DOI: 10.1007/s11910-014-0488-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
29
|
Downey RF, Sullivan FJ, Wang-Johanning F, Ambs S, Giles FJ, Glynn SA. Human endogenous retrovirus K and cancer: Innocent bystander or tumorigenic accomplice? Int J Cancer 2014; 137:1249-57. [PMID: 24890612 PMCID: PMC6264888 DOI: 10.1002/ijc.29003] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 05/02/2014] [Accepted: 05/09/2014] [Indexed: 12/20/2022]
Abstract
Harbored as relics of ancient germline infections, human endogenous retroviruses (HERVs) now constitute up to 8% of our genome. A proportion of this sequence has been co-opted for molecular and cellular processes, beneficial to human physiology, such as the fusogenic activity of the envelope protein, a vital component of placentogenesis. However, the discovery of high levels of HERV-K mRNA and protein and even virions in a wide array of cancers has revealed that HERV-K may be playing a more sinister role–a role as an etiological agent in cancer itself. Whether the presence of this retroviral material is simply an epiphenomenon, or an actual causative factor, is a hotly debated topic. This review will summarize the current state of knowledge regarding HERV-K and cancer and attempt to outline the potential mechanisms by which HERV-K could be involved in the onset and promotion of carcinogenesis.
Collapse
Affiliation(s)
- Ronan F Downey
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland
| | - Francis J Sullivan
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland.,Department of Radiation Oncology, Galway University Hospitals, Galway, Ireland
| | | | - Stefan Ambs
- Laboratory of Human Carcinogenesis, National Cancer Institute, Bethesda, MD
| | - Francis J Giles
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland.,HRB Clinical Research Facilities Galway & Dublin, National University of Ireland Galway and Trinity College Dublin, Galway, Ireland
| | - Sharon A Glynn
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland
| |
Collapse
|
30
|
Trans-activation, post-transcriptional maturation, and induction of antibodies to HERV-K (HML-2) envelope transmembrane protein in HIV-1 infection. Retrovirology 2014; 11:10. [PMID: 24472118 PMCID: PMC3907665 DOI: 10.1186/1742-4690-11-10] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 01/07/2014] [Indexed: 12/22/2022] Open
Abstract
Background Human Endogenous Retroviruses (HERVs) comprise about 8% of the human genome and have lost their ability to replicate or to produce infectious particles after having accumulated mutations over time. We assessed the kinetics of expression of HERV-K (HML-2) Envelope mRNA transcript and surface unit (SU) and transmembrane (TM) subunit proteins during HIV-1 infection. We also mapped the specificity of the humoral response to HERV-K (HML-2) Envelope protein in HIV-1 infected subjects at different stages of disease, and correlated the response with plasma viral load. Results We found that HIV-1 modified HERV-K (HML-2) Env mRNA expression, resulting in the expression of a fully N-glycosylated HERV-K (HML-2) envelope protein on the cell surface. Serological mapping of HERV-K (HML-2) envelope protein linear epitopes revealed two major immunogenic domains, one on SU and another on the ectodomain of TM. The titers of HERV-K (HML-2) TM antibodies were dramatically increased in HIV-1 infected subjects (p < 0.0001). HIV-1 infected adults who control HIV-1 in the absence of therapy (“elite” controllers) had a higher titer response against TM compared to antiretroviral-treated adults (p < 0.0001) and uninfected adults (p < 0.0001). Conclusions These data collectively suggest that HIV-1 infection induces fully glycosylated HERV-K (HML-2) envelope TM protein to which antibodies are induced. These anti-HERV-K (HML-2) TM antibodies are a potential marker of HIV-1 infection, and are at higher titer in elite controllers. HERV-K (HML-2) envelope TM protein may be a new therapeutic target in HIV-1 infection.
Collapse
|
31
|
Kreimer U, Schulz WA, Koch A, Niegisch G, Goering W. HERV-K and LINE-1 DNA Methylation and Reexpression in Urothelial Carcinoma. Front Oncol 2013; 3:255. [PMID: 24133654 PMCID: PMC3783855 DOI: 10.3389/fonc.2013.00255] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 09/11/2013] [Indexed: 11/16/2022] Open
Abstract
Changes in DNA methylation frequently accompany cancer development. One prominent change is an apparently genome-wide decrease in methylcytosine that is often ascribed to DNA hypomethylation at retroelements comprising nearly half the genome. DNA hypomethylation may allow reactivation of retroelements, enabling retrotransposition, and causing gene expression disturbances favoring tumor development. However, neither the extent of hypomethylation nor of retroelement reactivation are precisely known. We therefore assessed DNA methylation and expression of three major classes of retroelements (LINE-1, HERV-K, and AluY) in human urinary bladder cancer tissues and cell lines by pyrosequencing and quantitative reverse transcription–polymerase chain reaction, respectively. We found substantial global LINE-1 DNA hypomethylation in bladder cancer going along with a shift toward full-length LINE-1 expression. Thus, pronounced differences in LINE-1 expression were observed, which may be promoted, among others, by LINE-1 hypomethylation. Significant DNA hypomethylation was found at the HERV-K_22q11.23 proviral long terminal repeat (LTR) in bladder cancer tissues but without reactivation of its expression. DNA methylation of HERVK17, essentially absent from normal urothelial cells, was elevated in cell lines from invasive bladder cancers. Accordingly, the faint expression of HERVK17 in normal urothelial cells disappeared in such cancer cell lines. Of 16 additional HERV-Ks, expression of 7 could be detected in the bladder, albeit generally at low levels. Unlike in prostate cancers, none of these showed significant expression changes in bladder cancer. In contrast, expression of the AluYb8 but not of the AluYa5 family was significantly increased in bladder cancer tissues. Collectively, our findings demonstrate a remarkable specificity of changes in expression and DNA methylation of retroelements in bladder cancer with a significantly different pattern from that in prostate cancer.
Collapse
Affiliation(s)
- Ulrike Kreimer
- Department of Urology, Medical Faculty, Heinrich Heine University , Düsseldorf , Germany
| | | | | | | | | |
Collapse
|
32
|
Cherkasova E, Weisman Q, Childs RW. Endogenous retroviruses as targets for antitumor immunity in renal cell cancer and other tumors. Front Oncol 2013; 3:243. [PMID: 24062992 PMCID: PMC3775266 DOI: 10.3389/fonc.2013.00243] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/03/2013] [Indexed: 11/13/2022] Open
Abstract
Human endogenous retroviruses (HERVs), remnants of ancient germ-line infections with exogenous retroviruses, are estimated to comprise up to 8% of human genome. Most HERVs have accumulated mutations and deletions that prevent their expression as an infectious virus. Nevertheless, a growing number of HERV genes and proteins have been found to be expressed in different cancers, raising the possibility that HERV-derived antigens might represent excellent targets for tumor immunotherapy. Here, we review data showing HERV-encoded antigens are capable of eliciting humoral and T-cells specific antitumor immunity. We also describe a novel HERV-E that was recently found to be selectively expressed in over 80% of clear cell kidney cancer but not in normal tissues. Remarkably, the restricted expression of HERV-E in kidney tumors was found to occur as a consequence of inactivation of the von Hippel-Lindau tumor suppressor. Importantly, antigens derived from this provirus are immunogenic, stimulating cytotoxic T-cells that kill kidney cancer cells in vitro and in vivo. Taken altogether, these data suggest efforts aimed at boosting human immunity against HERV-derived antigens could be used as a strategy to treat advanced tumors including kidney cancer.
Collapse
Affiliation(s)
- Elena Cherkasova
- Hematology Branch, National Heart, Lung and Blood Institute, National Institutes of Health , Bethesda, MD , USA
| | | | | |
Collapse
|
33
|
Katoh I, Kurata SI. Association of endogenous retroviruses and long terminal repeats with human disorders. Front Oncol 2013; 3:234. [PMID: 24062987 PMCID: PMC3769647 DOI: 10.3389/fonc.2013.00234] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 08/27/2013] [Indexed: 01/31/2023] Open
Abstract
Since the human genome sequences became available in 2001, our knowledge about the human transposable elements which comprise ∼40% of the total nucleotides has been expanding. Non-long terminal repeat (non-LTR) retrotransposons are actively transposing in the present-day human genome, and have been found to cause ∼100 identified clinical cases of varied disorders. In contrast, almost all of the human endogenous retroviruses (HERVs) originating from ancient infectious retroviruses lost their infectivity and transposing activity at various times before the human-chimpanzee speciation (∼6 million years ago), and no known HERV is presently infectious. Insertion of HERVs and mammalian apparent LTR retrotransposons (MaLRs) into the chromosomal DNA influenced a number of host genes in various modes during human evolution. Apart from the aspect of genome evolution, HERVs and solitary LTRs being suppressed in normal biological processes can potentially act as extra transcriptional apparatuses of cellular genes by re-activation in individuals. There has been a reasonable prediction that aberrant LTR activation could trigger malignant disorders and autoimmune responses if epigenetic changes including DNA hypomethylation occur in somatic cells. Evidence supporting this hypothesis has begun to emerge only recently: a MaLR family LTR activation in the pathogenesis of Hodgkin’s lymphoma and a HERV-E antigen expression in an anti-renal cell carcinoma immune response. This mini review addresses the impacts of the remnant-form LTR retrotransposons on human pathogenesis.
Collapse
Affiliation(s)
- Iyoko Katoh
- Department of Microbiology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi , Chuo, Yamanashi , Japan
| | | |
Collapse
|
34
|
Yu HL, Zhao ZK, Zhu F. The role of human endogenous retroviral long terminal repeat sequences in human cancer (Review). Int J Mol Med 2013; 32:755-62. [PMID: 23900638 DOI: 10.3892/ijmm.2013.1460] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Accepted: 05/30/2013] [Indexed: 11/06/2022] Open
Abstract
Human endogenous retrovirus (HERV) and solitary long terminal repeats (LTRs) constitute 8% of the human genome. Although most HERV genes are partially deleted and not intact, HERV LTRs comprise features including promoters, enhancers, selective splicer sites and polyadenylation sites in order to regulate the expression of neighboring genes. Owing to the genetic instability of LTRs, their wide distributions along human chromosomes are not only non-random, but are also correlated with gene density. Considerable evidence indicates that HERV LTRs regulate the expression of their adjacent viral and cellular genes in placental development and tumorigenesis. However, the regulatory mechanism of HERV LTRs on the expression of its neighboring cancer-associated genes in human cancers remains to be elucidated. Insertional mutagenesis, recombination and polymorphism are three principal factors of LTR that contribute to its genetic instability. Moreover, genetic instability, hypomethylation, transactivation and the antisense transcript of LTRs enhance the activity of LTRs and regulate the expression of their adjacent genes in human cancers. Therefore, in the present review, we examined the mechanism of HERV LTRs in tumorigenesis in combination with the structure and function of LTRs.
Collapse
Affiliation(s)
- Hong-Lian Yu
- Department of Medical Microbiology, School of Medicine, Wuhan University, Wuhan, Hubei 430071, PR China
| | | | | |
Collapse
|
35
|
Overcoming intratumor heterogeneity of polygenic cancer drug resistance with improved biomarker integration. Neoplasia 2013; 14:1278-89. [PMID: 23308059 DOI: 10.1593/neo.122096] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 12/11/2012] [Accepted: 12/11/2012] [Indexed: 12/14/2022] Open
Abstract
Improvements in technology and resources are helping to advance our understanding of cancer-initiating events as well as factors involved with tumor progression, adaptation, and evasion of therapy. Tumors are well known to contain diverse cell populations and intratumor heterogeneity affords neoplasms with a diverse set of biologic characteristics that can be used to evolve and adapt. Intratumor heterogeneity has emerged as a major hindrance to improving cancer patient care. Polygenic cancer drug resistance necessitates reconsidering drug designs to include polypharmacology in pursuit of novel combinatorial agents having multitarget activity to overcome the diverse and compensatory signaling pathways in which cancer cells use to survive and evade therapy. Advances will require integration of different biomarkers such as genomics and imaging to provide for more adequate elucidation of the spatially varying location, type, and extent of diverse intratumor signaling molecules to provide for a rationale-based personalized cancer medicine strategy.
Collapse
|
36
|
Manghera M, Douville RN. Endogenous retrovirus-K promoter: a landing strip for inflammatory transcription factors? Retrovirology 2013; 10:16. [PMID: 23394165 PMCID: PMC3598470 DOI: 10.1186/1742-4690-10-16] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 02/01/2013] [Indexed: 12/24/2022] Open
Abstract
Humans are symbiotic organisms; our genome is populated with a substantial number of endogenous retroviruses (ERVs), some remarkably intact, while others are remnants of their former selves. Current research indicates that not all ERVs remain silent passengers within our genomes; re-activation of ERVs is often associated with inflammatory diseases. ERVK is the most recently endogenized and transcriptionally active ERV in humans, and as such may potentially contribute to the pathology of inflammatory disease. Here, we showcase the transcriptional regulation of ERVK. Expression of ERVs is regulated in part by epigenetic mechanisms, but also depends on transcriptional regulatory elements present within retroviral long terminal repeats (LTRs). These LTRs are responsive to both viral and cellular transcription factors; and we are just beginning to appreciate the full complexity of transcription factor interaction with the viral promoter. In this review, an exploration into the inflammatory transcription factor sites within the ERVK LTR will highlight the possible mechanisms by which ERVK is induced in inflammatory diseases.
Collapse
Affiliation(s)
- Mamneet Manghera
- Department of Biology, The University of Winnipeg, Winnipeg, MB, Canada
| | | |
Collapse
|
37
|
The interconnectedness of cancer cell signaling. Neoplasia 2012; 13:1183-93. [PMID: 22241964 DOI: 10.1593/neo.111746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 12/14/2011] [Accepted: 12/14/2011] [Indexed: 11/18/2022] Open
Abstract
The elegance of fundamental and applied research activities have begun to reveal a myriad of spatial and temporal alterations in downstream signaling networks affected by cell surface receptor stimulation including G protein-coupled receptors and receptor tyrosine kinases. Interconnected biochemical pathways serve to integrate and distribute the signaling information throughout the cell by orchestration of complex biochemical circuits consisting of protein interactions and covalent modification processes. It is clear that scientific literature summarizing results from both fundamental and applied scientific research activities has served to provide a broad foundational biologic database that has been instrumental in advancing our continued understanding of underlying cancer biology. This article reflects on historical advances and the role of innovation in the competitive world of grant-sponsored research.
Collapse
|