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Fan J, Qin Z. Roles of Human Endogenous Retrovirus-K-Encoded Np9 in Human Diseases: A Small Protein with Big Functions. Viruses 2024; 16:581. [PMID: 38675923 PMCID: PMC11054019 DOI: 10.3390/v16040581] [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: 03/24/2024] [Revised: 04/08/2024] [Accepted: 04/09/2024] [Indexed: 04/28/2024] Open
Abstract
Human Endogenous Retrovirus Sequences (HERVs) constitute up to 8% of the human genome, yet not all HERVs remain silent passengers within our genomes. Some HERVs, especially HERV type K (HERV-K), have been found to be frequently transactivated in a variety of inflammatory diseases and human cancers. Np9, a small protein translated from the HERV-K env reading frame, has been reported as an oncogenic protein and is present in a variety of tumors and transformed cells. The Np9 protein can crosstalk with many cellular factors and is involved in the pathogenicity of various diseases, including some oncogenic virus infections. In the current review, we summarize recent findings about Np9 clinical relevance/implications, its mediated cellular functions/mechanisms, and potential targeted therapies in development.
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Affiliation(s)
| | - Zhiqiang Qin
- Department of Pathology, Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, 4301 W Markham St., Little Rock, AR 72205, USA;
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2
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da Silva AL, Guedes BLM, Santos SN, Correa GF, Nardy A, Nali LHDS, Bachi ALL, Romano CM. Beyond pathogens: the intriguing genetic legacy of endogenous retroviruses in host physiology. Front Cell Infect Microbiol 2024; 14:1379962. [PMID: 38655281 PMCID: PMC11035796 DOI: 10.3389/fcimb.2024.1379962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 03/22/2024] [Indexed: 04/26/2024] Open
Abstract
The notion that viruses played a crucial role in the evolution of life is not a new concept. However, more recent insights suggest that this perception might be even more expansive, highlighting the ongoing impact of viruses on host evolution. Endogenous retroviruses (ERVs) are considered genomic remnants of ancient viral infections acquired throughout vertebrate evolution. Their exogenous counterparts once infected the host's germline cells, eventually leading to the permanent endogenization of their respective proviruses. The success of ERV colonization is evident so that it constitutes 8% of the human genome. Emerging genomic studies indicate that endogenous retroviruses are not merely remnants of past infections but rather play a corollary role, despite not fully understood, in host genetic regulation. This review presents some evidence supporting the crucial role of endogenous retroviruses in regulating host genetics. We explore the involvement of human ERVs (HERVs) in key physiological processes, from their precise and orchestrated activities during cellular differentiation and pluripotency to their contributions to aging and cellular senescence. Additionally, we discuss the costs associated with hosting a substantial amount of preserved viral genetic material.
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Affiliation(s)
- Amanda Lopes da Silva
- Instituto de Medicina Tropical de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Bruno Luiz Miranda Guedes
- Instituto de Medicina Tropical de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Samuel Nascimento Santos
- UNISA Research Center, Universidade Santo Amaro, Post-Graduation in Health Sciences, São Paulo, Brazil
| | - Giovanna Francisco Correa
- Instituto de Medicina Tropical de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Ariane Nardy
- UNISA Research Center, Universidade Santo Amaro, Post-Graduation in Health Sciences, São Paulo, Brazil
| | | | - Andre Luis Lacerda Bachi
- UNISA Research Center, Universidade Santo Amaro, Post-Graduation in Health Sciences, São Paulo, Brazil
| | - Camila Malta Romano
- Instituto de Medicina Tropical de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
- Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brazil
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3
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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.
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Affiliation(s)
| | | | - Richard W. Childs
- Laboratory of Transplantation Immunotherapy, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States
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4
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Dopkins N, Singh B, Michael S, Zhang P, Marston JL, Fei T, Singh M, Feschotte C, Collins N, Bendall ML, Nixon DF. Ribosomal profiling of human endogenous retroviruses in healthy tissues. BMC Genomics 2024; 25:5. [PMID: 38166631 PMCID: PMC10759522 DOI: 10.1186/s12864-023-09909-x] [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: 06/05/2023] [Accepted: 12/14/2023] [Indexed: 01/05/2024] Open
Abstract
Human endogenous retroviruses (HERVs) are the germline embedded proviral fragments of ancient retroviral infections that make up roughly 8% of the human genome. Our understanding of HERVs in physiology primarily surrounds their non-coding functions, while their protein coding capacity remains virtually uncharacterized. Therefore, we applied the bioinformatic pipeline "hervQuant" to high-resolution ribosomal profiling of healthy tissues to provide a comprehensive overview of translationally active HERVs. We find that HERVs account for 0.1-0.4% of all translation in distinct tissue-specific profiles. Collectively, our study further supports claims that HERVs are actively translated throughout healthy tissues to provide sequences of retroviral origin to the human proteome.
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Affiliation(s)
- Nicholas Dopkins
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, 10021, USA.
| | - Bhavya Singh
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Stephanie Michael
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Panpan Zhang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14850, USA
| | - Jez L Marston
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Tongyi Fei
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Manvendra Singh
- Clinical Neuroscience, Max Planck Institute for Multidisciplinary Sciences, City Campus, Göttingen, Germany
| | - Cedric Feschotte
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14850, USA
| | - Nicholas Collins
- Jill Roberts Institute for Research in Inflammatory Bowel Disease, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Matthew L Bendall
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Douglas F Nixon
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, 10021, USA
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5
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Mehta K, Yentsch H, Lee J, Gao TT, Zhang K. Phosphatidylinositol 3-phosphate mediates Arc capsids secretion through the multivesicular body pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.19.572392. [PMID: 38187623 PMCID: PMC10769229 DOI: 10.1101/2023.12.19.572392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Activity-regulated cytoskeleton-associated protein (Arc/Arg3.1) is an immediate early gene that plays a vital role in learning and memory. The recent discovery that Arc mediates the inter-neuronal RNA transfer implies its role in regulating neuronal functions across long distances. Arc protein has structural and functional properties similar to viral Group-specific antigen (Gag). By assembling into high-order, virus-like capsids, Arc mediates the intercellular RNA transfer. However, the exact secretion pathway through which Arc capsids maneuver cargos is unclear. Here, we identified that Arc capsids assemble and secrete through the endosomal-multivesicular body (MVB) pathway. Arc's endosomal entry is likely mediated by phosphatidylinositol-3-phosphate (PI3P). Indeed, reconstituted Arc protein preferably binds to PI3P. In mammalian cells, Arc forms puncta that colocalizes with FYVE, an endosomal PI3P marker, and competitive binding to PI3P via prolonged FYVE expression reduces the average number of Arc puncta per cell. Overexpression of MTMR1, a PI3P phosphatase, significantly reduces Arc capsid secretion. Arc capsids secrete through the endosomal-MVB axis as extracellular vesicles. Live-cell imaging shows that fluorescently labeled Arc primarily colocalizes Rab5 and CD63, early endosomal and MVB markers, respectively. Superresolution imaging resolves Arc accumulates within the intraluminal vesicles of MVB. CRISPR double knockout of RalA and RalB, crucial GTPases for MVB biogenesis and exocytosis, severely reduces Arc-mediated RNA transfer efficiency. These results suggest that, unlike the Human Immunodeficiency Virus Gag, which assembles on and bud off from the plasma membrane, Arc capsids assemble at the endocytic membranes of the endosomal-MVB pathway mediated by PI3P. Understanding Arc's secretion pathway helps gain insights into its role in intercellular cargo transfer and highlights the commonality and distinction of trafficking mechanisms between structurally resembled capsid proteins.
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6
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Katoh H, Honda T. Roles of Human Endogenous Retroviruses and Endogenous Virus-Like Elements in Cancer Development and Innate Immunity. Biomolecules 2023; 13:1706. [PMID: 38136578 PMCID: PMC10741599 DOI: 10.3390/biom13121706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 11/18/2023] [Accepted: 11/21/2023] [Indexed: 12/24/2023] Open
Abstract
Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections in the host genome. Although mutations and silencing mechanisms impair their original role in viral replication, HERVs are believed to play roles in various biological processes. Long interspersed nuclear elements (LINEs) are non-LTR retrotransposons that have a lifecycle resembling that of retroviruses. Although LINE expression is typically silenced in somatic cells, it also contributes to various biological processes. The aberrant expression of HERVs and LINEs is closely associated with the development of cancer and/or immunological diseases, suggesting that they are integrated into various pathways related to the diseases. HERVs/LINEs control gene expression depending on the context as promoter/enhancer elements. Some RNAs and proteins derived from HERVs/LINEs have oncogenic potential, whereas others stimulate innate immunity. Non-retroviral endogenous viral elements (nrEVEs) are a novel type of virus-like element in the genome. nrEVEs may also be involved in host immunity. This article provides a current understanding of how these elements impact cellular physiology in cancer development and innate immunity, and provides perspectives for future studies.
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Affiliation(s)
- Hirokazu Katoh
- Department of Virology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan;
| | - Tomoyuki Honda
- Department of Virology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan;
- Department of Virology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
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7
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Chabukswar S, Grandi N, Lin LT, Tramontano E. Envelope Recombination: A Major Driver in Shaping Retroviral Diversification and Evolution within the Host Genome. Viruses 2023; 15:1856. [PMID: 37766262 PMCID: PMC10536682 DOI: 10.3390/v15091856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/21/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023] Open
Abstract
Endogenous retroviruses (ERVs) are integrated into host DNA as the result of ancient germ line infections, primarily by extinct exogenous retroviruses. Thus, vertebrates' genomes contain thousands of ERV copies, providing a "fossil" record for ancestral retroviral diversity and its evolution within the host genome. Like other retroviruses, the ERV proviral sequence consists of gag, pro, pol, and env genes flanked by long terminal repeats (LTRs). Particularly, the env gene encodes for the envelope proteins that initiate the infection process by binding to the host cellular receptor(s), causing membrane fusion. For this reason, a major element in understanding ERVs' evolutionary trajectory is the characterization of env changes over time. Most of the studies dedicated to ERVs' env have been aimed at finding an "actual" physiological or pathological function, while few of them have focused on how these genes were once acquired and modified within the host. Once acquired into the organism, genome ERVs undergo common cellular events, including recombination. Indeed, genome recombination plays a role in ERV evolutionary dynamics. Retroviral recombination events that might have been involved in env divergence include the acquisition of env genes from distantly related retroviruses, env swapping facilitating multiple cross-species transmission over millions of years, ectopic recombination between the homologous sequences present in different positions in the chromosomes, and template switching during transcriptional events. The occurrence of these recombinational events might have aided in shaping retroviral diversification and evolution until the present day. Hence, this review describes and discusses in detail the reported recombination events involving ERV env to provide the basis for further studies in the field.
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Affiliation(s)
- Saili Chabukswar
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, 09042 Cagliari, Italy; (S.C.); (N.G.)
- International Ph.D. Program in Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan
| | - Nicole Grandi
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, 09042 Cagliari, Italy; (S.C.); (N.G.)
| | - Liang-Tzung Lin
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan;
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 110, Taiwan
| | - Enzo Tramontano
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, 09042 Cagliari, Italy; (S.C.); (N.G.)
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8
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Stricker E, Peckham-Gregory EC, Scheurer ME. CancerHERVdb: Human Endogenous Retrovirus (HERV) Expression Database for Human Cancer Accelerates Studies of the Retrovirome and Predictions for HERV-Based Therapies. J Virol 2023; 97:e0005923. [PMID: 37255431 PMCID: PMC10308937 DOI: 10.1128/jvi.00059-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 05/10/2023] [Indexed: 06/01/2023] Open
Abstract
In this study, we sought to create a database summarizing the expression of human endogenous retroviruses (HERVs) in various human cancers. HERVs are suitable therapeutic targets due to their abundance in the human genome, overexpression in various malignancies, and involvement in various cancer pathways. We identified articles on HERVs from PubMed and then prescreened and automatically categorized them using the portable document format (PDF) data extractor (PDE) R package. We discovered 196 primary research articles with HERV expression data from cancer tissues or cancer cell lines. HERV RNA and protein expression was reported in brain, breast, cervical, colorectal, endocrine, gastrointestinal, kidney/renal/pelvis, liver, lung, genital, oral cavity, pharynx, ovary, pancreas, prostate, skin, testicular, urinary/bladder, and uterus cancers, leukemias, lymphomas, and myelomas. Additionally, we discovered reports of HERV RNA-only overexpression in soft tissue cancers including heart, thyroid, bone, and joint cancers. The CancerHERVdb database is hosted in the form of interactive visualizations of the expression data and a summary data table at https://erikstricker.shinyapps.io/cancerHERVdb/. The user can filter the findings according to cancer type, HERV family, HERV gene, or a combination thereof and easily export the results with the corresponding reference list. In our report, we provide examples of potential uses of the CancerHERVdb, such as identification of cancers suitable for off-target treatment with the multiple sclerosis-associated retrovirus (MSRV)-Env-targeting antibody GNbAC1 (now named temelimab) currently in phase 2b clinical trials for multiple sclerosis or the discovery of cancers overexpressing HERV-H long terminal repeat-associating 2 (HHLA2), a newly emerging immune checkpoint. In summary, the CancerHERVdb allows cross-study comparisons, encourages data exploration, and informs about potential off-target effects of HERV-targeting treatments. IMPORTANCE Human endogenous retroviruses (HERVs), which in the past have inserted themselves in various regions of the human genome, are to various degrees activated in virtually every cancer type. While a centralized naming system and resources summarizing HERV levels in cancers are lacking, the CancerHERVdb database provides a consolidated resource for cross-study comparisons, data exploration, and targeted searches of HERV activation. The user can access data extracted from hundreds of articles spanning 25 human cancer categories. Therefore, the CancerHERVdb database can aid in the identification of prognostic and risk markers, drivers of cancer, tumor-specific targets, multicancer spanning signals, and targets for immune therapies. Consequently, the CancerHERVdb database is of direct relevance for clinical as well as basic research.
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Affiliation(s)
- Erik Stricker
- Baylor College of Medicine, Department of Molecular Virology and Microbiology, Houston, Texas, USA
- Baylor College of Medicine, Department of Pediatrics, Houston, Texas, USA
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9
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Hosseiniporgham S, Sechi LA. Anti-HERV-K Drugs and Vaccines, Possible Therapies against Tumors. Vaccines (Basel) 2023; 11:vaccines11040751. [PMID: 37112663 PMCID: PMC10144246 DOI: 10.3390/vaccines11040751] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/20/2023] [Accepted: 03/21/2023] [Indexed: 03/31/2023] Open
Abstract
The footprint of human endogenous retroviruses (HERV), specifically HERV-K, has been found in malignancies, such as melanoma, teratocarcinoma, osteosarcoma, breast cancer, lymphoma, and ovary and prostate cancers. HERV-K is characterized as the most biologically active HERV due to possession of open reading frames (ORF) for all Gag, Pol, and Env genes, which enables it to be more infective and obstructive towards specific cell lines and other exogenous viruses, respectively. Some factors might contribute to carcinogenicity and at least one of them has been recognized in various tumors, including overexpression/methylation of long interspersed nuclear element 1 (LINE-1), HERV-K Gag, and Env genes themselves plus their transcripts and protein products, and HERV-K reverse transcriptase (RT). Therapies effective for HERV-K-associated tumors mostly target invasive autoimmune responses or growth of tumors through suppression of HERV-K Gag or Env protein and RT. To design new therapeutic options, more studies are needed to better understand whether HERV-K and its products (Gag/Env transcripts and HERV-K proteins/RT) are the initiators of tumor formation or just the disorder’s developers. Accordingly, this review aims to present evidence that highlights the association between HERV-K and tumorigenicity and introduces some of the available or potential therapies against HERV-K-induced tumors.
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10
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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.
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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
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11
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Saha B, Vannucci L, Saha B, Tenti P, Baral R. Evolvability and emergence of tumor heterogeneity as a space-time function. Cytokine 2023; 161:156061. [PMID: 36252436 DOI: 10.1016/j.cyto.2022.156061] [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: 04/04/2022] [Revised: 09/20/2022] [Accepted: 09/30/2022] [Indexed: 11/22/2022]
Abstract
The loss of control of cell proliferation, apoptosis regulation and contact inhibition leads to tumor development. While benign tumors are restricted to their primary space, i.e. where these tumors first originate, the metastatic tumors not only disseminate- facilitated by hypoxia-driven neovascularization- to distant secondary sites but also show substantial changes in metabolism, tissue architectures, gene expression profiles and immune phenotypes. All these alterations result in radio-, chemo- and immune-resistance rendering these metastatic tumor cells refractory to therapy. Since the beginning of the transformation, these factors- which influence each other- are incorporated to the developing and metastasizing tumor. As a result, the complexities in the heterogeneity of tumor progressively increase. This space-time function in the heterogeneity of tumors is generated by various conditions and factors at the genetic as well as microenvironmental levels, for example, endogenous retroviruses, methylation and epigenetic dysregulation that may be etiology-specific, cancer associated inflammation, remodeling of the extracellular matrix and mesenchymal cell shifted functions. On the one hand, these factors may cause de-differentiation of the tumor cells leading to cancer stem cells that contribute to radio-, chemo- and immune-resistance and recurrence of tumors. On the other hand, they may also enhance the heterogeneity under specific microenvironment-driven proliferation. In this editorial, we intend to underline the importance of heterogeneity in cancer progress, its evaluation and its use in correlation with the tumor evolution in a specific patient as a field of research for achieving precise patient-tailored treatments and amelioration of diagnostic (monitoring) tools and prognostic capacity.
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Affiliation(s)
- Bhaskar Saha
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
| | - Luca Vannucci
- Institute of Microbiology, Czech Academy of Sciences, Videnska 1083, Praha, Czech Republic.
| | - Baibaswata Saha
- Institute of Microbiology, Czech Academy of Sciences, Videnska 1083, Praha, Czech Republic
| | - Paolo Tenti
- Institute of Microbiology, Czech Academy of Sciences, Videnska 1083, Praha, Czech Republic
| | - Rathindranath Baral
- Chittaranjan National Cancer Institute, Shyamaprasad Mukherjee Road, Calcutta 700026, India.
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12
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Kitsou K, Lagiou P, Magiorkinis G. Human endogenous retroviruses in cancer: Oncogenesis mechanisms and clinical implications. J Med Virol 2023; 95:e28350. [PMID: 36428242 PMCID: PMC10108094 DOI: 10.1002/jmv.28350] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 11/28/2022]
Abstract
Human Endogenous Retroviruses (HERVs) are viral sequences integrated into the human genome, resulting from the infection of human germ-line cells by ancient exogenous retroviruses. Despite losing their replication and retrotransposition abilities, HERVs appear to have been co-opted in human physiological functions while their aberrant expression is linked to human disease. The role of HERVs in multiple malignancies has been demonstrated, however, the extent to which HERV activation and expression participate in the development of cancer is not yet fully comprehended. In this review article, we discuss the presumed role of HERVs in carcinogenesis and their promising diagnostic and prognostic implications. Additionally, we explore recent data on the HERVs in cancer therapeutics, either through the manipulation of their expression, to induce antitumor innate immunity responses or as cancer immunotherapy targets. Finally, more precise and higher resolution high-throughput sequencing approaches will further elucidate HERV participation in human physiological and pathological processes.
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Affiliation(s)
- Konstantina Kitsou
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian, University of Athens, Goudi, Greece
| | - Pagona Lagiou
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian, University of Athens, Goudi, Greece
| | - Gkikas Magiorkinis
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian, University of Athens, Goudi, Greece
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13
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Li T, Zhang G, Zhang X, Lin H, Liu Q. The 8p11 myeloproliferative syndrome: Genotypic and phenotypic classification and targeted therapy. Front Oncol 2022; 12:1015792. [PMID: 36408177 PMCID: PMC9669583 DOI: 10.3389/fonc.2022.1015792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 10/10/2022] [Indexed: 10/05/2023] Open
Abstract
EMS(8p11 myeloproliferative syndrome, EMS) is an aggressive hematological neoplasm with/without eosinophilia caused by a rearrangement of the FGFR1 gene at 8p11-12. It was found that all cases carry chromosome abnormalities at the molecular level, not only the previously reported chromosome translocation and insertion but also a chromosome inversion. These abnormalities produced 17 FGFR1 fusion genes, of which the most common partner genes are ZNF198 on 13q11-12 and BCR of 22q11.2. The clinical manifestations can develop into AML (acute myeloid leukemia), T-LBL (T-cell lymphoblastic lymphoma), CML (chronic myeloid leukemia), CMML (chronic monomyelocytic leukemia), or mixed phenotype acute leukemia (MPAL). Most patients are resistant to traditional chemotherapy, and a minority of patients achieve long-term clinical remission after stem cell transplantation. Recently, the therapeutic effect of targeted tyrosine kinase inhibitors (such as pemigatinib and infigratinib) in 8p11 has been confirmed in vitro and clinical trials. The TKIs may become an 8p11 treatment option as an alternative to hematopoietic stem cell transplantation, which is worthy of further study.
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Affiliation(s)
- Taotao Li
- Department of Hematology, The First Hospital of Jilin University, Changchun, China
| | - Gaoling Zhang
- Department of Hematology, The First Hospital of Jilin University, Changchun, China
| | - Xiaoling Zhang
- Key Laboratory of Organ Regeneration and Transplantation of Ministry of Education, First Hospital, Jilin University, Changchun, China
- National-Local Joint Engineering Laboratory of Animal Models for Human Disease, First Hospital, Jilin University, Changchun, China
| | - Hai Lin
- Department of Hematology, The First Hospital of Jilin University, Changchun, China
| | - Qiuju Liu
- Department of Hematology, The First Hospital of Jilin University, Changchun, China
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14
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Transcriptome Analysis of Human Endogenous Retroviruses at Locus-Specific Resolution in Non-Small Cell Lung Cancer. Cancers (Basel) 2022; 14:cancers14184433. [PMID: 36139593 PMCID: PMC9497127 DOI: 10.3390/cancers14184433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/28/2022] [Accepted: 09/10/2022] [Indexed: 11/16/2022] Open
Abstract
Lung cancer is the second most commonly diagnosed cancer and the leading cause of cancer deaths worldwide. Among its subtypes, lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) are the most common, accounting for more than 85% of lung cancer diagnoses. Despite the incredible efforts and recent advances in lung cancer treatments, patients affected by this condition still have a poor prognosis. Therefore, novel diagnostic biomarkers are needed. Recently, a class of transposable elements called human endogenous retroviruses (HERVs) has been found to be implicated in cancer development and later employed as novel biomarkers for several tumor types. In this study, we first ever characterized the expression of HERVs at genomic locus-specific resolution in both LUAD and LUSC cohorts available in The Cancer Genome Atlas (TCGA). Precisely, (i) we profiled the expression of HERVs in TCGA-LUAD and TCGA-LUSC cohorts; (ii) we identified the dysregulated HERVs in both lung cancer subtypes; (iii) we evaluated the impact of the dysregulated HERVs on signaling pathways using neural network-based predictions; and (iv) we assessed their association with overall survival (OS) and relapse-free survival (RFS). In conclusion, we believe this study may help elucidate another layer of dysregulation that occurs in lung cancer involving HERVs, paving the way for identifying novel lung cancer biomarkers.
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15
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Rivas SR, Valdez MJM, Govindarajan V, Seetharam D, Doucet-O’Hare TT, Heiss JD, Shah AH. The Role of HERV-K in Cancer Stemness. Viruses 2022; 14:v14092019. [PMID: 36146825 PMCID: PMC9504571 DOI: 10.3390/v14092019] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/29/2022] [Accepted: 09/05/2022] [Indexed: 12/15/2022] Open
Abstract
Human endogenous retrovirus-K (HERV-K) is the most recently integrated retrovirus in the human genome, with implications for multiple disorders, including cancer. Although typically transcriptionally silenced in normal adult cells, dysregulation of HERV-K (HML-2) elements has been observed in cancer, including breast, germ cell tumors, pancreatic, melanoma, and brain cancer. While multiple methods of carcinogenesis have been proposed, here we discuss the role of HERV-K (HML-2) in the promotion and maintenance of the stem-cell in cancer. Aberrant expression of HERV-K has been shown to promote expression of stem cell markers and promote dedifferentiation. In this review, we discuss HERV-K (HML-2) as a potential therapeutic target based on evidence that some tumors depend on the expression of its proteins for survival.
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Affiliation(s)
- Sarah R. Rivas
- Surgical Neurology Branch, National Institute of Neurological Diseases and Stroke, Bethesda, MD 20892, USA
- Correspondence: (S.R.R.); (A.H.S.)
| | - Mynor J. Mendez Valdez
- Section of Virology and Immunotherapy, Department of Neurosurgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Vaidya Govindarajan
- Section of Virology and Immunotherapy, Department of Neurosurgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Deepa Seetharam
- Section of Virology and Immunotherapy, Department of Neurosurgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Tara T. Doucet-O’Hare
- Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - John D. Heiss
- Surgical Neurology Branch, National Institute of Neurological Diseases and Stroke, Bethesda, MD 20892, USA
| | - Ashish H. Shah
- Section of Virology and Immunotherapy, Department of Neurosurgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA
- Correspondence: (S.R.R.); (A.H.S.)
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16
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Zhang Q, Pan J, Cong Y, Mao J. Transcriptional Regulation of Endogenous Retroviruses and Their Misregulation in Human Diseases. Int J Mol Sci 2022; 23:ijms231710112. [PMID: 36077510 PMCID: PMC9456331 DOI: 10.3390/ijms231710112] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/28/2022] [Accepted: 09/01/2022] [Indexed: 11/22/2022] Open
Abstract
Endogenous retroviruses (ERVs), deriving from exogenous retroviral infections of germ line cells occurred millions of years ago, represent ~8% of human genome. Most ERVs are highly inactivated because of the accumulation of mutations, insertions, deletions, and/or truncations. However, it is becoming increasingly apparent that ERVs influence host biology through genetic and epigenetic mechanisms under particular physiological and pathological conditions, which provide both beneficial and deleterious effects for the host. For instance, certain ERVs expression is essential for human embryonic development. Whereas abnormal activation of ERVs was found to be involved in numbers of human diseases, such as cancer and neurodegenerative diseases. Therefore, understanding the mechanisms of regulation of ERVs would provide insights into the role of ERVs in health and diseases. Here, we provide an overview of mechanisms of transcriptional regulation of ERVs and their dysregulation in human diseases.
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17
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Off-Target Effect of Activation of NF-κB by HIV Latency Reversal Agents on Transposable Elements Expression. Viruses 2022; 14:v14071571. [PMID: 35891551 PMCID: PMC9318874 DOI: 10.3390/v14071571] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/14/2022] [Accepted: 07/18/2022] [Indexed: 12/31/2022] Open
Abstract
Many drugs have been evaluated to reactivate HIV-1 from cellular reservoirs, but the off-target effects of these latency reversal agents (LRA) remain poorly defined. Transposable elements (TEs) are reactivated during HIV-1 infection, but studies of potential off-target drug effects on TE expression have been limited. We analyzed the differential expression of TEs induced by canonical and non-canonical NF-κB signaling. We evaluated the effect of PKC agonists (Bryostatin and Ingenol B) on the expression of TEs in memory CD4+ T cells. Ingenol B induced 38 differentially expressed TEs (17 HERV (45%) and 21 L1 (55%)). Interestingly, TE expression in effector memory CD4+ T cells was more affected by Bryostatin compared to other memory T-cell subsets, with 121 (107 upregulated and 14 downregulated) differentially expressed (DE) TEs. Of these, 31% (n = 37) were HERVs, and 69% (n = 84) were LINE-1 (L1). AZD5582 induced 753 DE TEs (406 HERV (54%) and 347 L1 (46%)). Together, our findings show that canonical and non-canonical NF-κB signaling activation leads to retroelement expressions as an off-target effect. Furthermore, our data highlights the importance of exploring the interaction between LRAs and the expression of retroelements in the context of HIV-1 eradication strategies.
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18
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HERV-K and HERV-H Env Proteins Induce a Humoral Response in Prostate Cancer Patients. Pathogens 2022; 11:pathogens11010095. [PMID: 35056043 PMCID: PMC8778306 DOI: 10.3390/pathogens11010095] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 01/10/2022] [Accepted: 01/13/2022] [Indexed: 02/01/2023] Open
Abstract
A higher expression of human endogenous retroviruses (HERVs) has been associated with several malignancies, including prostate cancer, implying a possible use as a diagnostic or prognostic cancer biomarker. For this reason, we examined the humoral response against different epitopes obtained from the envelope protein of HERV-K (HERV-K env-su19–37, HERV-K env-su109–126), HERV-H (HERV-H env-su229–241, HERV-H env387–399) and HERV-W (HERV-W env-su93–108, HERV-W env-su248–262) in the plasma of patients affected by prostate cancer (PCa), and compared to that of benign prostate hyperplasia (BPH) and a borderline group of patients with atypical small acinar proliferation (ASAP) and prostate intraepithelial neoplasia (PIN) and healthy controls. A significant antibody response was observed against HERV-K env-su109–126 (p = 0.004) and HERV-H env-su229–241 (p < 0.0001) in PCa patients compared to HCs, BPH and borderline cohorts, whilst no significance difference was found in the antibodies against HERV-W env-su93–108 and HERV-W env-su248–262 in patients with PCa. Our results provided further proof of the association between HERV-K and PCa and added new evidence about the possible involvement of HERV-H in PCa pathogenesis, highlighting their possibility of being used as biomarkers of the disease.
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19
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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.
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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
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20
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Maze EA, Agit B, Reeves S, Hilton DA, Parkinson DB, Laraba L, Ercolano E, Kurian KM, Hanemann CO, Belshaw RD, Ammoun S. Human endogenous retrovirus type K promotes proliferation and confers sensitivity to anti-retroviral drugs in Merlin-negative schwannoma and meningioma. Cancer Res 2021; 82:235-247. [PMID: 34853069 DOI: 10.1158/0008-5472.can-20-3857] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 03/04/2021] [Accepted: 11/15/2021] [Indexed: 11/16/2022]
Abstract
Deficiency of the tumour suppressor Merlin causes development of schwannoma, meningioma, and ependymoma tumours, which can occur spontaneously or in the hereditary disease neurofibromatosis type 2 (NF2). Merlin mutations are also relevant in a variety of other tumours. Surgery and radiotherapy are current first-line treatments; however, tumours frequently recur with limited treatment options. Here, we use human Merlin-negative schwannoma and meningioma primary cells to investigate the involvement of the endogenous retrovirus HERV-K in tumour development. HERV-K proteins previously implicated in tumorigenesis were overexpressed in schwannoma and all meningioma grades, and disease-associated CRL4DCAF1 and YAP/TEAD pathways were implicated in this overexpression. In normal Schwann cells, ectopic overexpression of HERV-K Env increased proliferation and upregulated expression of c-Jun and pERK1/2, which are key components of known tumorigenic pathways in schwannoma, JNK/c-Jun and RAS/RAF/MEK/ERK. Furthermore, FDA-approved retroviral protease inhibitors ritonavir, atazanavir, and lopinavir reduced proliferation of schwannoma and grade I meningioma cells. These results identify HERV-K as a critical regulator of progression in Merlin-deficient tumours and offer potential strategies for therapeutic intervention.
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Affiliation(s)
- Emmanuel A Maze
- School of Biomedical Sciences, Faculty of Health Medicine, Dentistry and Human Sciences, Plymouth University
| | - Bora Agit
- Faculty of Health Medicine, Dentistry and Human Sciences, Plymouth University
| | - Shona Reeves
- Faculty of Health Medicine, Dentistry and Human Sciences, Plymouth University
| | - David A Hilton
- Faculty of Health Medicine, Dentistry and Human Sciences, Plymouth University
| | - David B Parkinson
- Institute of Translational and Stratified Medicine, Plymouth University Peninsula Schools of Medicine and Dentistry
| | - Liyam Laraba
- Institute of Translational and Stratified Medicine, Plymouth University Peninsula Schools of Medicine and Dentistry
| | | | - Kathreena M Kurian
- Department of Neuropathology, Brain Tumour Research Group, Frenchay Hospital, University of Bristol
| | - C Oliver Hanemann
- Institute of Translational and Stratified Medicine, Plymouth University Peninsula Schools of Medicine and Dentistry
| | | | - Sylwia Ammoun
- Faculty of Health Medicine, Dentistry and Human Sciences, Plymouth University
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21
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Mao J, Zhang Q, Cong YS. Human endogenous retroviruses in development and disease. Comput Struct Biotechnol J 2021; 19:5978-5986. [PMID: 34849202 PMCID: PMC8604659 DOI: 10.1016/j.csbj.2021.10.037] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 10/29/2021] [Accepted: 10/29/2021] [Indexed: 12/16/2022] Open
Abstract
Human endogenous retroviruses (HERVs) represent ∼8% of human genome, deriving from exogenous retroviral infections of germ line cells occurred millions of years ago and being inherited by the offspring in a Mendelian fashion. Most of HERVs are nonprotein-coding because of the accumulation of mutations, insertions, deletions, and/or truncations. It has been long thought that HERVs were "junk DNA". However, it is now known that HERVs are involved in various biological processes through encoding proteins, acting as promoters/enhancers, or lncRNAs to affect human health and disease. In this review, we summarized recent findings about HERVs, with implications in embryonic development, pluripotency, cancer, aging, and neurodegenerative diseases.
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Affiliation(s)
- Jian Mao
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University School of Basic Medical Sciences, Hangzhou, China
| | - Qian Zhang
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University School of Basic Medical Sciences, Hangzhou, China
| | - Yu-Sheng Cong
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University School of Basic Medical Sciences, Hangzhou, China
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22
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Li X, Guo Y, Li H, Huang X, Pei Z, Wang X, Liu Y, Jia L, Li T, Bao Z, Wang X, Han L, Han J, Li J, Li L. Infection by Diverse HIV-1 Subtypes Leads to Different Elevations in HERV-K Transcriptional Levels in Human T Cell Lines. Front Microbiol 2021; 12:662573. [PMID: 34079529 PMCID: PMC8165174 DOI: 10.3389/fmicb.2021.662573] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/23/2021] [Indexed: 01/08/2023] Open
Abstract
Human endogenous retroviruses (HERVs) make up ~8% of the human genome, and for millions of years, they have been subject to strict biological regulation. Many HERVs do not participate in normal physiological activities in the body. However, in some pathological conditions, they can be abnormally activated. For example, HIV infection can cause abnormal activation of HERVs, and under different infection conditions, HERV expression may be different. We observed significant differences in HERV-K transcription levels among HIV-1 subtype-infected individuals. The transcriptional levels in the HERV-K gag region were significantly increased in HIV-1 B subtype-infected patients, while the transcriptional levels in the HERV-K pol region were significantly increased in CRF01_AE and CRF07_BC subtype-infected patients. In vitro, the transcriptional levels of HEVR-K were increased 5-fold and 15-fold in MT2 cells transfected with two different HIV-1 strains (B and CRF01_AE, respectively). However, there was no significant difference in transcriptional levels among regions of HERV-K. When MT2 cells were infected with different subtypes of HIV-1 Tat proteins (B, CRF01_AE), which is constructed by lentiviruses, and the transcription levels of HERV-K were increased 4-fold and 2-fold, respectively. Thus, different subtypes of HIV-1 have different effects on HERV-K transcription levels, which may be caused by many factors, not only Tat protein.
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Affiliation(s)
- Xi Li
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yaolin Guo
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Hanping Li
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaofeng Huang
- The Second Medical Center, National Clinical Research Center for Geriatric Diseases, Chinese PLA General Hospital, Beijing, China
| | - Zhichao Pei
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaolin Wang
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yongjian Liu
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Lei Jia
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Tianyi Li
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zuoyi Bao
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaorui Wang
- Department of Microbiological Laboratory Technology, School of Public Health, Cheeloo College of Medicine, Shandong University, Key Laboratory of Infectious Disease Control and Prevention in Universities of Shandong, Jinan, China
| | - Leilei Han
- School of Public Health and Affiliated Shijiazhuang Fifth Hospital, North China University of Science and Technology, Tangshan, China
| | - Jingwan Han
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jingyun Li
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Lin Li
- State Key Laboratory of Pathogen and Biosecurity, Department of AIDS Research, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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23
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Jansz N, Faulkner GJ. Endogenous retroviruses in the origins and treatment of cancer. Genome Biol 2021; 22:147. [PMID: 33971937 PMCID: PMC8108463 DOI: 10.1186/s13059-021-02357-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 04/21/2021] [Indexed: 02/07/2023] Open
Abstract
Endogenous retroviruses (ERVs) are emerging as promising therapeutic targets in cancer. As remnants of ancient retroviral infections, ERV-derived regulatory elements coordinate expression from gene networks, including those underpinning embryogenesis and immune cell function. ERV activation can promote an interferon response, a phenomenon termed viral mimicry. Although ERV expression is associated with cancer, and provisionally with autoimmune and neurodegenerative diseases, ERV-mediated inflammation is being explored as a way to sensitize tumors to immunotherapy. Here we review ERV co-option in development and innate immunity, the aberrant contribution of ERVs to tumorigenesis, and the wider biomedical potential of therapies directed at ERVs.
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Affiliation(s)
- Natasha Jansz
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD, 4102, Australia.
| | - Geoffrey J Faulkner
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD, 4102, Australia. .,Queensland Brain Institute, University of Queensland, Brisbane, QLD, 4072, Australia.
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24
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Kristensen MK, Christensen T. Regulation of the expression of human endogenous retroviruses: elements in fetal development and a possible role in the development of cancer and neurological diseases. APMIS 2021; 129:241-253. [PMID: 33683784 DOI: 10.1111/apm.13130] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 03/03/2021] [Indexed: 12/14/2022]
Abstract
Human endogenous retroviruses (HERVs) are remnants of ancient retroviral germline infections. Most HERV sequences are silenced in somatic cells, but interest is emerging on the involvement of HERV derived transcripts and proteins in human physiology and disease. A HERV-W encoded protein, syncytin-1, has been co-opted into fetal physiology, where it plays a role in trophoblast formation. Altered HERV transcription and expression of HERV derived proteins are associated with various cancer types and neurological diseases such as multiple sclerosis (MS). The implication of HERVs as potential mediators of both health and disease suggests important roles of regulatory mechanisms and alterations of these in physiological and pathological processes. The regulation of HERV sequences is mediated by a wide variety of mechanisms, and the focus of this review is on selected aspects of these, including epigenetic mechanisms such as CpG methylation and histone modifications of the HP1-H3K9me axis, viral transactivation events, and regulatory perspectives of transient stimuli in the microenvironment. Increasing knowledge of the regulation of HERV sequences will not only contribute to the understanding of complex pathogeneses, but also may pinpoint potential targets for better diagnosis and treatment in complex diseases as MS.
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25
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Weber M, Padmanabhan Nair V, Bauer T, Sprinzl MF, Protzer U, Vincendeau M. Increased HERV-K(HML-2) Transcript Levels Correlate with Clinical Parameters of Liver Damage in Hepatitis C Patients. Cells 2021; 10:cells10040774. [PMID: 33807462 PMCID: PMC8065411 DOI: 10.3390/cells10040774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/27/2021] [Accepted: 03/29/2021] [Indexed: 12/23/2022] Open
Abstract
Chronic hepatitis C virus (HCV) infection is closely associated with a plethora of diseases, including cancers and autoimmune disorders. However, the distinct triggers and cellular networks leading to such HCV-derived diseases are poorly understood. Around 8% of the human genome consists of human endogenous retroviruses. They are usually silenced but can be reactivated by environmental conditions, including viral infections. Our current understanding indicates that the activation of one specific family-namely, HERV-K(HML-2)-is linked to distinct pathologies, including cancer and autoimmunity. In this study, we analyzed the transcription levels of HERV-K(HML-2) in 42 HCV-infected patients receiving direct-acting antiviral therapies. Samples from the start of treatment until 12 weeks post-treatment were investigated. Our results show increased HERV-K(HML-2) transcript levels in patients with HCV-derived liver cirrhosis throughout the observation period. Several clinical parameters specifying poor liver function are positively correlated with HERV-K(HML-2) expression. Of note, patients without a sustained viral clearance showed a drastic increase in HERV-K(HML-2) transcript levels. Together, our data suggest that increased HERV-K(HML-2) expression is correlated with reduced liver function as well as therapy success in HCV-infected patients.
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Affiliation(s)
- Melanie Weber
- Institute of Virology, HelmholtzZentrum München, Neuherberg 85764, Germany; (M.W.); (V.P.N.); (T.B.)
| | - Vidya Padmanabhan Nair
- Institute of Virology, HelmholtzZentrum München, Neuherberg 85764, Germany; (M.W.); (V.P.N.); (T.B.)
| | - Tanja Bauer
- Institute of Virology, HelmholtzZentrum München, Neuherberg 85764, Germany; (M.W.); (V.P.N.); (T.B.)
- Institute of Virology, Technische Universität München, Munich 81675, Germany
- German Center for Infection Research (DZIF), Partner Site, Munich 81675, Germany
| | - Martin F. Sprinzl
- Medical Department, University Hospital Mainz, Mainz 55131, Germany;
| | - Ulrike Protzer
- Institute of Virology, HelmholtzZentrum München, Neuherberg 85764, Germany; (M.W.); (V.P.N.); (T.B.)
- Institute of Virology, Technische Universität München, Munich 81675, Germany
- German Center for Infection Research (DZIF), Partner Site, Munich 81675, Germany
- Correspondence: (U.P.); (M.V.)
| | - Michelle Vincendeau
- Institute of Virology, HelmholtzZentrum München, Neuherberg 85764, Germany; (M.W.); (V.P.N.); (T.B.)
- Correspondence: (U.P.); (M.V.)
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26
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HERV-K Gag RNA and Protein Levels Are Elevated in Malignant Regions of the Prostate in Males with Prostate Cancer. Viruses 2021; 13:v13030449. [PMID: 33802118 PMCID: PMC7999808 DOI: 10.3390/v13030449] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 12/14/2022] Open
Abstract
Heightened expression of human endogenous retrovirus (HERV) sequences has been associated with a range of malignancies, including prostate cancer, suggesting that they may serve as useful diagnostic or prognostic cancer biomarkers. We analysed the expression of HERV-K (Gag and Env/Np9 regions), HERV-E 4.1 (Pol and Env regions), HERV-H (Pol) and HERV-W (Gag) sequences in prostate cancer cells lines and normal prostate epithelial cells using qRT-PCR. HERV expression was also analysed in matched malignant and benign prostate tissue samples from men with prostate cancer (n = 27, median age 65.2 years (range 47-70)) and compared to prostate cancer-free male controls (n = 11). Prostate cancer epithelial cell lines exhibited a signature of HERV RNA overexpression, with all HERVs analysed, except HERV-E Pol, showing heightened expression in at least two, but more commonly all, cell lines analysed. Analysis of primary prostate material indicated increased expression of HERV-E Pol but decreased expression of HERV-E Env in both malignant and benign regions of the prostate in men with prostate cancer as compared to those without. Expression of HERV-K Gag was significantly higher in malignant regions of the prostate in men with prostate cancer as compared to matched benign regions and prostate cancer-free men (p < 0.001 for both), with 85.2% of prostate cancers donors showing malignancy-associated upregulation of HERV-K Gag RNA. HERV-K Gag protein was detected in 12/18 (66.7%) malignant tissues using immunohistochemistry, but only 1/18 (5.6%) benign tissue sections. Heightened expression of HERV-K Gag RNA and protein appears to be a sensitive and specific biomarker of prostate malignancy in this cohort of men with prostate carcinoma, supporting its potential utility as a non-invasive, adjunct clinical biomarker.
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27
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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: 25] [Impact Index Per Article: 6.3] [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.
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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
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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.
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Liu CH, Grandi N, Palanivelu L, Tramontano E, Lin LT. Contribution of Human Retroviruses to Disease Development-A Focus on the HIV- and HERV-Cancer Relationships and Treatment Strategies. Viruses 2020; 12:E852. [PMID: 32759845 PMCID: PMC7472297 DOI: 10.3390/v12080852] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/28/2020] [Accepted: 07/31/2020] [Indexed: 02/06/2023] Open
Abstract
Animal retroviruses are known for their transforming potential, and this is also true for the ones hosted by humans, which have gathered expanding attention as one of the potent causative agents in various disease, including specific cancer types. For instance, Human T Lymphotropic virus (HTLV) is a well-studied class of oncoviruses causing T cell leukemia, while human immunodeficiency virus (HIV) leads to acquired immunodeficiency syndrome (AIDS), which is linked to a series of defining cancers including Kaposi sarcoma, certain types of non-Hodgkin lymphoma, and cervical cancer. Of note, in addition to these "modern" exogenous retroviruses, our genome harbors a staggering number of human endogenous retroviruses (HERVs). HERVs are the genetic remnants of ancient retroviral germline infection of human ancestors and are typically silenced in normal tissues due to inactivating mutations and sequence loss. While some HERV elements have been appropriated and contribute to human physiological functions, others can be reactivated through epigenetic dysregulations to express retroviral elements and promote carcinogenesis. Conversely, HERV replication intermediates or protein products can also serve as intrinsic pathogen-associated molecular patterns that cause the immune system to interpret it as an exogenous infection, thereby stimulating immune responses against tumors. As such, HERVs have also been targeted as a potential internal strategy to sensitize tumor cells for promising immunotherapies. In this review, we discuss the dynamic role of human retroviruses in cancer development, focusing on HIV and HERVs contribution. We also describe potential treatment strategies, including immunotherapeutic targeting of HERVs, inhibiting DNA methylation to expose HERV signatures, and the use of antiretroviral drugs against HIV and HERVs, which can be employed as prospective anti-cancer modalities.
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Affiliation(s)
- Ching-Hsuan Liu
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Department of Microbiology & Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Nicole Grandi
- Department of Life and Environmental Sciences, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (N.G.); (E.T.)
| | - Lalitha Palanivelu
- International Master Program in Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
| | - Enzo Tramontano
- Department of Life and Environmental Sciences, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (N.G.); (E.T.)
| | - Liang-Tzung Lin
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
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30
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Turelli P, Playfoot C, Grun D, Raclot C, Pontis J, Coudray A, Thorball C, Duc J, Pankevich EV, Deplancke B, Busskamp V, Trono D. Primate-restricted KRAB zinc finger proteins and target retrotransposons control gene expression in human neurons. SCIENCE ADVANCES 2020; 6:eaba3200. [PMID: 32923624 PMCID: PMC7455193 DOI: 10.1126/sciadv.aba3200] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 07/16/2020] [Indexed: 05/11/2023]
Abstract
In the first days of embryogenesis, transposable element-embedded regulatory sequences (TEeRS) are silenced by Kruppel-associated box (KRAB) zinc finger proteins (KZFPs). Many TEeRS are subsequently co-opted in transcription networks, but how KZFPs influence this process is largely unknown. We identify ZNF417 and ZNF587 as primate-specific KZFPs repressing HERVK (human endogenous retrovirus K) and SVA (SINE-VNTR-Alu) integrants in human embryonic stem cells (ESCs). Expressed in specific regions of the human developing and adult brain, ZNF417/587 keep controlling TEeRS in ESC-derived neurons and brain organoids, secondarily influencing the differentiation and neurotransmission profile of neurons and preventing the induction of neurotoxic retroviral proteins and an interferon-like response. Thus, evolutionarily recent KZFPs and their TE targets partner up to influence human neuronal differentiation and physiology.
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Affiliation(s)
- Priscilla Turelli
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Christopher Playfoot
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Dephine Grun
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Charlène Raclot
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Julien Pontis
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Alexandre Coudray
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Christian Thorball
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Julien Duc
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Eugenia V. Pankevich
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Bart Deplancke
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Volker Busskamp
- Center for Regenerative Therapies, Technische Universität Dresden, Dresden, Germany
- Faculty of Medicine, Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Didier Trono
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Corresponding author.
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31
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Salavatiha Z, Soleimani-Jelodar R, Jalilvand S. The role of endogenous retroviruses-K in human cancer. Rev Med Virol 2020; 30:1-13. [PMID: 32734655 DOI: 10.1002/rmv.2142] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/22/2020] [Accepted: 06/23/2020] [Indexed: 12/15/2022]
Abstract
It is known that human endogenous retroviruses (HERVs) constitute almost 8% of the human genome. Although the expression of HERVs from the human genome is tightly regulated, different exogenous and endogenous factors could trigger HERV activation. Aberrant expression of different HERVs may potentially cause a variety of diseases such as neurological and autoimmune diseases as well as cancer. It is suggested that HERV-K can induce cancer through different mechanisms that are discussed. The interplay between some tumor viruses and HERV-K seems to be a key player in progression of viral-associated cancers because elevated levels of Rec and Np9 proteins are observed in several cancers. The frequent over expression of HERV proteins and some specific antibodies in cancer cells could be considered as suitable prognostic and therapeutic biomarkers in diagnosis and treatment of cancers. The expression of HERV proteins in cancers and development of immune responses against them may also be used as targets for cancer immunotherapy. Further studies are warranted to evaluate the role of HERVs in cancer formation and use of different HERV proteins in developing new diagnostic and therapeutic approaches for cancer treatments.
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Affiliation(s)
- Zahra Salavatiha
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Rahim Soleimani-Jelodar
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Somayeh Jalilvand
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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32
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Xue B, Sechi LA, Kelvin DJ. Human Endogenous Retrovirus K (HML-2) in Health and Disease. Front Microbiol 2020; 11:1690. [PMID: 32765477 PMCID: PMC7380069 DOI: 10.3389/fmicb.2020.01690] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 06/29/2020] [Indexed: 02/05/2023] Open
Abstract
Human endogenous retroviruses (HERVs) are derived from exogenous retrovirus infections in the evolution of primates and account for about 8% of the human genome. They were considered as silent passengers within our genomes for a long time, however, reactivation of HERVs has been associated with tumors and autoimmune diseases, especially the HERV-K (HML-2) family, the most recent integration groups with the least number of mutations and the most biologically active to encode functional retroviral proteins and produce retrovirus-like particles. Increasing studies are committed to determining the potential role of HERV-K (HML-2) in pathogenicity. Although there is still no evidence for HERV-K (HML-2) as a direct cause of diseases, aberrant expression profiles of the HERV-K (HML-2) transcripts and their regulatory function to their proximal host-genes were identified in different diseases. In this review, we summarized the advances between HERV-K (HML-2) and diseases to provide basis for further studies on the causal relationship between HERV-K (HML-2) and diseases. We recommended more attention to polymorphic integrated HERV-K (HML-2) loci which could be genetic causative factors and be associated with inter-individual differences in tumorigenesis and autoimmune diseases.
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Affiliation(s)
- Bei Xue
- Division of Immunology, Shantou University Medical College, Shantou, China
- Department of Microbiology and Immunology, Canadian Center for Vaccinology, Dalhousie University, Halifax, NS, Canada
| | - Leonardo A. Sechi
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
- Mediterranean Center for Disease Control, University of Sassari, Sassari, Italy
| | - David J. Kelvin
- Division of Immunology, Shantou University Medical College, Shantou, China
- Department of Microbiology and Immunology, Canadian Center for Vaccinology, Dalhousie University, Halifax, NS, Canada
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
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33
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Human Endogenous Retrovirus K in Cancer: A Potential Biomarker and Immunotherapeutic Target. Viruses 2020; 12:v12070726. [PMID: 32640516 PMCID: PMC7412025 DOI: 10.3390/v12070726] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/26/2020] [Accepted: 06/29/2020] [Indexed: 12/16/2022] Open
Abstract
In diseases where epigenetic mechanisms are changed, such as cancer, many genes show altered gene expression and inhibited genes become activated. Human endogenous retrovirus type K (HERV-K) expression is usually inhibited in normal cells from healthy adults. In tumor cells, however, HERV-K mRNA expression has been frequently documented to increase. Importantly, HERV-K-derived proteins can act as tumor-specific antigens, a class of neoantigens, and induce immune responses in different types of cancer. In this review, we describe the function of the HERV-K HML-2 subtype in carcinogenesis as biomarkers, and their potential as targets for cancer immunotherapy.
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Gray LR, Jackson RE, Jackson PEH, Bekiranov S, Rekosh D, Hammarskjöld ML. HIV-1 Rev interacts with HERV-K RcREs present in the human genome and promotes export of unspliced HERV-K proviral RNA. Retrovirology 2019; 16:40. [PMID: 31842941 PMCID: PMC6916052 DOI: 10.1186/s12977-019-0505-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 12/07/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The HERV-K (HML-2) viruses are the youngest of the human endogenous retroviruses. They are present as several almost complete proviral copies and numerous fragments in the human genome. Many HERV-K proviruses express a regulatory protein Rec, which binds to an element present in HERV-K mRNAs called the RcRE. This interaction is necessary for the nucleo-cytoplasmic export and expression of HERV-K mRNAs that retain introns and plays a role analogous to that of Rev and the RRE in HIV replication. There are over 900 HERV-K RcREs distributed throughout the human genome. Thus, it was of interest to determine if Rev could functionally interact with selected RcRE elements that map either to HERV-K proviruses or human gene regions. This interaction would have the potential to alter the expression of both HERV-K mRNAs and cellular mRNAs during HIV-1 infection. RESULTS In this study we employed a combination of RNAseq, bioinformatics and cell-based functional assays. Potential RcREs were identified through a number of bioinformatic approaches. They were then tested for their ability to promote export and translation of a reporter mRNA with a retained intron in conjunction with Rev or Rec. Some of the selected elements functioned well with either Rev, Rec or both, whereas some showed little or no function. Rev function on individual RcREs varied and was also dependent on the Rev sequence. We also performed RNAseq on total and cytoplasmic RNA isolated from SupT1 cells expressing HIV Rev, with or without Tat, or HERV-K Rec. Proviral mRNA from three HERV-K loci (4p16.1b, 22q11.23 and most significantly 3q12.3) accumulated in the cytoplasm in the presence of Rev or Tat and Rev, but not Rec. Consistent with this, the 3' RcRE from 3q12.3 functioned well with HIV-Rev in our reporter assay. In contrast, this RcRE showed little or no function with Rec. CONCLUSIONS The HIV Rev protein can functionally interact with many RcREs present in the human genome, depending on the RcRE sequence, as well as the Rev sequence. This leads to export of some of the HERV-K proviral mRNAs and also has the potential to change the expression of non-viral genes.
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Affiliation(s)
- Laurie R Gray
- Myles H. Thaler Center for AIDS and Human Retrovirus Research and the Department of Microbiology, Immunology, Cancer Biology, University of Virginia, Charlottesville, 22908, USA
| | - Rachel E Jackson
- Myles H. Thaler Center for AIDS and Human Retrovirus Research and the Department of Microbiology, Immunology, Cancer Biology, University of Virginia, Charlottesville, 22908, USA
| | - Patrick E H Jackson
- Myles H. Thaler Center for AIDS and Human Retrovirus Research and the Department of Microbiology, Immunology, Cancer Biology, University of Virginia, Charlottesville, 22908, USA
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, 22908, USA
| | - Stefan Bekiranov
- Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, 22908, USA
| | - David Rekosh
- Myles H. Thaler Center for AIDS and Human Retrovirus Research and the Department of Microbiology, Immunology, Cancer Biology, University of Virginia, Charlottesville, 22908, USA
| | - Marie-Louise Hammarskjöld
- Myles H. Thaler Center for AIDS and Human Retrovirus Research and the Department of Microbiology, Immunology, Cancer Biology, University of Virginia, Charlottesville, 22908, USA.
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35
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Tavakolian S, Goudarzi H, Lak E, Faghihloo E. The evaluation of HERV-K env, np9, rec, gag expression in normal, polyp and cancerous tissues of gastric and colon. Future Virol 2019. [DOI: 10.2217/fvl-2019-0114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Aim: Gastrointestinal cancer is one of the most alarming cancers worldwide. Infections exert an impact on tumor progression in gastrointestinal tissues. The alteration in the expression of human endogenous retrovirus-K ( HERV-K) genes could remarkably induce oncogenic activity. Materials & methods: In 22 gastric and 23 colon cancer patients, the expression level of HERV-K env, rec, gag and np9 were evaluated. Results: While there was a slight increase in the expression of HERV-K env in colon cancer tissues, the expression level of this gene decreased in gastric tissues. Moreover, the expression of both np9 and gag HERV-K were upregulated only in colon cancer. Nevertheless, rec HERV-K was downregulated in gastric cancer tissues. Conclusion: HERV-K-associated genes can be used as a possible biomarker for cancers diagnosis.
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Affiliation(s)
- Shaian Tavakolian
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Goudarzi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Elena Lak
- Department of gastric & liver, Emam Hossein hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ebrahim Faghihloo
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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36
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Rigogliuso G, Biniossek ML, Goodier JL, Mayer B, Pereira GC, Schilling O, Meese E, Mayer J. A human endogenous retrovirus encoded protease potentially cleaves numerous cellular proteins. Mob DNA 2019; 10:36. [PMID: 31462935 PMCID: PMC6707001 DOI: 10.1186/s13100-019-0178-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 08/13/2019] [Indexed: 11/21/2022] Open
Abstract
Background A considerable portion of the human genome derives from retroviruses inherited over millions of years. Human endogenous retroviruses (HERVs) are usually severely mutated, yet some coding-competent HERVs exist. The HERV-K(HML-2) group includes evolutionarily young proviruses that encode typical retroviral proteins. HERV-K(HML-2) has been implicated in various human diseases because transcription is often upregulated and some of its encoded proteins are known to affect cell biology. HERV-K(HML-2) Protease (Pro) has received little attention so far, although it is expressed in some disease contexts and other retroviral proteases are known to process cellular proteins. Results We set out to identify human cellular proteins that are substrates of HERV-K(HML-2) Pro employing a modified Terminal Amine Isotopic Labeling of Substrates (TAILS) procedure. Thousands of human proteins were identified by this assay as significantly processed by HERV-K(HML-2) Pro at both acidic and neutral pH. We confirmed cleavage of a majority of selected human proteins in vitro and in co-expression experiments in vivo. Sizes of processing products observed for some of the tested proteins coincided with product sizes predicted by TAILS. Processed proteins locate to various cellular compartments and participate in diverse, often disease-relevant cellular processes. A limited number of HERV-K(HML-2) reference and non-reference loci appears capable of encoding active Pro. Conclusions Our findings from an approach combining TAILS with experimental verification of candidate proteins in vitro and in cultured cells suggest that hundreds of cellular proteins are potential substrates of HERV-K(HML-2) Pro. It is therefore conceivable that even low-level expression of HERV-K(HML-2) Pro affects levels of a diverse array of proteins and thus has a functional impact on cell biology and possible relevance for human diseases. Further studies are indicated to elucidate effects of HERV-K(HML-2) Pro expression regarding human substrate proteins, cell biology, and disease. The latter also calls for studies on expression of specific HERV-K(HML-2) loci capable of encoding active Pro. Endogenous retrovirus-encoded Pro activity may also be relevant for disease development in species other than human. Electronic supplementary material The online version of this article (10.1186/s13100-019-0178-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Giuseppe Rigogliuso
- 1Department of Human Genetics, Medical Faculty, University of Saarland, Homburg, Germany
| | - Martin L Biniossek
- 2Institute of Molecular Medicine and Cell Research, University of Freiburg, Freiburg, Germany
| | - John L Goodier
- 3McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Bettina Mayer
- 2Institute of Molecular Medicine and Cell Research, University of Freiburg, Freiburg, Germany
| | - Gavin C Pereira
- 3McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Oliver Schilling
- 4Institute of Surgical Pathology, Medical Center, University of Freiburg, Freiburg, Germany.,5German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Eckart Meese
- 1Department of Human Genetics, Medical Faculty, University of Saarland, Homburg, Germany
| | - Jens Mayer
- 1Department of Human Genetics, Medical Faculty, University of Saarland, Homburg, Germany
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37
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Kaplan MH, Kaminski M, Estes JM, Gitlin SD, Zahn J, Elder JT, Tejasvi T, Gensterblum E, Sawalha AH, McGowan JP, Dosik MH, Direskeneli H, Direskeneli GS, Adebamowo SN, Adebamowo CA, Sajadi M, Contreras-Galindo R. Structural variation of centromeric endogenous retroviruses in human populations and their impact on cutaneous T-cell lymphoma, Sézary syndrome, and HIV infection. BMC Med Genomics 2019; 12:58. [PMID: 31046767 PMCID: PMC6498702 DOI: 10.1186/s12920-019-0505-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 04/15/2019] [Indexed: 12/16/2022] Open
Abstract
Background Human Endogenous Retroviruses type K HML-2 (HK2) are integrated into 117 or more areas of human chromosomal arms while two newly discovered HK2 proviruses, K111 and K222, spread extensively in pericentromeric regions, are the first retroviruses discovered in these areas of our genome. Methods We use PCR and sequencing analysis to characterize pericentromeric K111 proviruses in DNA from individuals of diverse ethnicities and patients with different diseases. Results We found that the 5′ LTR-gag region of K111 proviruses is missing in certain individuals, creating pericentromeric instability. K111 deletion (−/− K111) is seen in about 15% of Caucasian, Asian, and Middle Eastern populations; it is missing in 2.36% of African individuals, suggesting that the −/− K111 genotype originated out of Africa. As we identified the −/−K111 genotype in Cutaneous T-cell lymphoma (CTCL) cell lines, we studied whether the −/−K111 genotype is associated with CTCL. We found a significant increase in the frequency of detection of the −/−K111 genotype in Caucasian patients with severe CTCL and/or Sézary syndrome (n = 35, 37.14%), compared to healthy controls (n = 160, 15.6%) [p = 0.011]. The −/−K111 genotype was also found to vary in HIV-1 infection. Although Caucasian healthy individuals have a similar frequency of detection of the −/− K111 genotype, Caucasian HIV Long-Term Non-Progressors (LTNPs) and/or elite controllers, have significantly higher detection of the −/−K111 genotype (30.55%; n = 36) than patients who rapidly progress to AIDS (8.5%; n = 47) [p = 0.0097]. Conclusion Our data indicate that pericentromeric instability is associated with more severe CTCL and/or Sézary syndrome in Caucasians, and appears to allow T-cells to survive lysis by HIV infection. These findings also provide new understanding of human evolution, as the −/−K111 genotype appears to have arisen out of Africa and is distributed unevenly throughout the world, possibly affecting the severity of HIV in different geographic areas. Electronic supplementary material The online version of this article (10.1186/s12920-019-0505-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mark H Kaplan
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Mark Kaminski
- Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Judith M Estes
- Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Scott D Gitlin
- Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA.,Ann Arbor Veterans Affairs Hospital, Ann Arbor, MI, 48105, USA
| | - Joseph Zahn
- Division of Dermatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - James T Elder
- Division of Dermatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA.,Ann Arbor Veterans Affairs Hospital, Ann Arbor, MI, 48105, USA
| | - Trilokraj Tejasvi
- Division of Dermatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA.,Ann Arbor Veterans Affairs Hospital, Ann Arbor, MI, 48105, USA
| | - Elizabeth Gensterblum
- Division of Rheumatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Amr H Sawalha
- Division of Rheumatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Joseph Patrick McGowan
- Division of Infectious Diseases, The Feinstein Institute for Medical research, Manhasset, NY, 11030, USA
| | | | - Haner Direskeneli
- Division of Rheumatology, School of Medicine, Marmara University, Istanbul, Turkey
| | | | - Sally N Adebamowo
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Clement A Adebamowo
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Mohammad Sajadi
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Rafael Contreras-Galindo
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA. .,Hormel Institute, University of Minnesota, Austin, MN, 55912, USA.
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Investigation of somatic single nucleotide variations in human endogenous retrovirus elements and their potential association with cancer. PLoS One 2019; 14:e0213770. [PMID: 30934003 PMCID: PMC6443178 DOI: 10.1371/journal.pone.0213770] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 02/28/2019] [Indexed: 11/19/2022] Open
Abstract
Human endogenous retroviruses (HERVs) have been investigated for potential links with human cancer. However, the distribution of somatic nucleotide variations in HERV elements has not been explored in detail. This study aims to identify HERV elements with an over-representation of somatic mutations (hot spots) in cancer patients. Four HERV elements with mutation hotspots were identified that overlap with exons of four human protein coding genes. These hotspots were identified based on the significant over-representation (p<8.62e-4) of non-synonymous single-nucleotide variations (nsSNVs). These genes are TNN (HERV-9/LTR12), OR4K15 (HERV-IP10F/LTR10F), ZNF99 (HERV-W/HERV17/LTR17), and KIR2DL1 (MST/MaLR). In an effort to identify mutations that effect survival, all nsSNVs were further evaluated and it was found that kidney cancer patients with mutation C2270G in ZNF99 have a significantly lower survival rate (hazard ratio = 2.6) compared to those without it. Among HERV elements in the human non-protein coding regions, we found 788 HERVs with significantly elevated numbers of somatic single-nucleotide variations (SNVs) (p<1.60e-5). From this category the top three HERV elements with significantly over-represented SNVs are HERV-H/LTR7, HERV-9/LTR12 and HERV-L/MLT2. Majority of the SNVs in these 788 HERV elements are located in three DNA functional groups: long non-coding RNAs (lncRNAs) (60%), introns (22.2%) and transcriptional factor binding sites (TFBS) (14.8%). This study provides a list of mutational hotspots in HERVs, which could potentially be used as biomarkers and therapeutic targets.
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Chan SM, Sapir T, Park SS, Rual JF, Contreras-Galindo R, Reiner O, Markovitz DM. The HERV-K accessory protein Np9 controls viability and migration of teratocarcinoma cells. PLoS One 2019; 14:e0212970. [PMID: 30818388 PMCID: PMC6394991 DOI: 10.1371/journal.pone.0212970] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/12/2019] [Indexed: 11/19/2022] Open
Abstract
Human endogenous retroviruses are remnants of ancient germline infections that make up approximately 8% of the modern human genome. The HERV-K (HML-2) family is one of the most recent entrants into the human germline, these viruses appear to be transcriptionally active, and HERV-K viral like particles (VLPs) are found in cell lines from a number of human malignancies. HERV-K VLPs were first found to be produced in teratocarcinoma cell lines, and since then teratocarcinoma has been thought of as the classical model for HERV-Ks, with the NCCIT teratocarcinoma cell line particularly known to produce VLPs. Treatment for teratocarcinoma has progressed since its discovery, with improved prognosis for patients. Since the introduction of platinum based therapy, first year survival has greatly improved even with disseminated disease; however, it is estimated that 20% to 30% of patients present with metastatic germ cell tumor relapse following initial treatments. Also, the toxicity associated with the use of chemotherapeutic agents used to treat germ cell tumors is still a major concern. In this study, we show that the depletion of the HERV-K accessory protein Np9 increases the sensitivity of NCCIT teratocarcinoma cells to bleomycin and cisplatin. While decreasing the expression of Np9 had only a modest effect on the baseline viability of the cells, the reduced expression of Np9 increased the sensitivity of the teratocarcinoma cells to environmental (serum starvation) and chemical (chemotherapeutic) stresses. Np9 is also essential to the migration of NCCIT teratocarcinoma cells: in a wound closure assay, reduced expression of Np9 resulted in cells migrating into the wound at a slower rate, whereas reintroduction of Np9 resulted in NCCIT cells migrating back into the wound in a manner similar to the control. These findings support the implication that the HERV-K accessory protein Np9 has oncogenic potential.
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Affiliation(s)
- Susana M. Chan
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Tamar Sapir
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Sung-Soo Park
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jean-François Rual
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Rafael Contreras-Galindo
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Orly Reiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - David M. Markovitz
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan, United States of America
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
- Graduate Program in Immunology, University of Michigan, Ann Arbor, Michigan, United States of America
- Cancer Biology Program, University of Michigan, Ann Arbor, Michigan, United States of America
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40
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Chen J, Foroozesh M, Qin Z. Transactivation of human endogenous retroviruses by tumor viruses and their functions in virus-associated malignancies. Oncogenesis 2019; 8:6. [PMID: 30643113 PMCID: PMC6331641 DOI: 10.1038/s41389-018-0114-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 10/24/2018] [Accepted: 11/26/2018] [Indexed: 02/07/2023] Open
Abstract
Human endogenous retroviruses (HERVs), viral-associated sequences, are normal components of the human genome and account for 8–9% of our genome. These original provirus sequences can be transactivated to produce functional products. Several reactivated HERVs have been implicated in cancers and autoimmune diseases. An emerging body of literature supports a potential role of reactivated HERVs in viral diseases, in particular viral-associated neoplasms. Demystifying studies on the mechanism(s) of HERV reactivation could provide a new framework for the development of treatment and prevention strategies targeting virus-associated tumors. Although available data suggest that co-infection by other viruses, such as Kaposi’s Sarcoma-associated herpesvirus (KSHV) and Epstein–Barr virus (EBV), may be a crucial driving force to transactivate HERV boom, the mechanisms of action of viral infection-induced HERV transactivation and the contributions of HERVs to viral oncogenesis warrant further studies. Here, we review viral co-infection contributes to HERVs transactivation with focus on human viral infection associated oncogenesis and diseases, including the abilities of viral regulators involved in HERV reactivation, and physiological effects of viral infection response on HERV reactivation.
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Affiliation(s)
- Jungang Chen
- Department of Pathology, Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, 4301 W Markham St, Little Rock, AR, 72205, USA
| | - Maryam Foroozesh
- Department of Chemistry, Xavier University of Louisiana, 1 Drexel Drive, New Orleans, LA, 70125, USA
| | - Zhiqiang Qin
- Department of Pathology, Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, 4301 W Markham St, Little Rock, AR, 72205, USA. .,Department of Pediatrics, East Hospital, Tongji University School of Medicine, 200120, Shanghai, China. .,Research Center for Translational Medicine and Key Laboratory of Arrhythmias, East Hospital, Tongji University School of Medicine, 200120, Shanghai, China.
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41
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Zhang M, Liang JQ, Zheng S. Expressional activation and functional roles of human endogenous retroviruses in cancers. Rev Med Virol 2019; 29:e2025. [PMID: 30614117 PMCID: PMC6590502 DOI: 10.1002/rmv.2025] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 10/26/2018] [Accepted: 11/05/2018] [Indexed: 12/26/2022]
Abstract
Human endogenous retroviruses (HERVs) are widely believed to be remnants of ancestral germ line infections by exogenous retroviruses. Although HERVs are deemed as “nonfunctional DNAs” due to loss of most of their viral protein coding capacity during evolution as part of the human genome, cumulative evidences are showing the expressional activation and potential roles of HERVs in diseases especially cancers. Work by other researchers and us has observed the dysregulation of HERVs in cancers, identified new HERV‐related genes, and revealed their potential importance in cancer development. Here, we summarized the current knowledge on the mechanisms of the expressional activation and functional roles of HERVs, with a focus on the H family HERV (HERV‐H), in carcinogenesis. HERV expression is regulated by external chemical or physical substances and exogenous virus infection, as well as host factors such as epigenetic DNA methylation, transcription factors, cytokines, and small RNAs. Diverse roles of HERVs have been proposed by acting in the forms of noncoding RNAs, proteins, and transcriptional regulators during carcinogenesis. However, much remains to be learnt about the contributions of HERVs to human cancers. More investigation is warranted to elucidate the functions of these “fossil remnants” yet important viral DNAs in the human genome.
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Affiliation(s)
- Mengwen Zhang
- The Department of Plastic and Reconstructive Surgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China.,Cancer Institute, Second Affiliated Hospital, and Ministry of Education Key Laboratory of Cancer Prevention and Intervention, Zhejiang University School of Medicine, Hangzhou, China
| | - Jessie Qiaoyi Liang
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Shu Zheng
- Cancer Institute, Second Affiliated Hospital, and Ministry of Education Key Laboratory of Cancer Prevention and Intervention, Zhejiang University School of Medicine, Hangzhou, China.,The Department of surgical oncology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
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42
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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: 110] [Impact Index Per Article: 18.3] [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.
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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
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43
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Matteucci C, Balestrieri E, Argaw-Denboba A, Sinibaldi-Vallebona P. Human endogenous retroviruses role in cancer cell stemness. Semin Cancer Biol 2018; 53:17-30. [PMID: 30317035 DOI: 10.1016/j.semcancer.2018.10.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/30/2018] [Accepted: 10/05/2018] [Indexed: 12/18/2022]
Abstract
Cancer incidence and mortality, metastasis, drug resistance and recurrence are still the critical issues of oncological diseases. In this scenario, increasing scientific evidences demonstrate that the activation of human endogenous retroviruses (HERVs) is involved in the aggressiveness of tumors such as melanoma, breast, germ cell, renal, ovarian, liver and haematological cancers. In their dynamic regulation, HERVs have also proved to be important determinants of pluripotency in human embryonic stem cells (ESC) and of the reprogramming process of induced pluripotent stem cells (iPSCs). In many types of tumors, essential characteristics of aggressiveness have been associated with the achievement of stemness features, often accompanied with the identification of defined subpopulations, termed cancer stem cells (CSCs), which possess stem cell-like properties and sustain tumorigenesis. Indeed, CSCs show high self-renewal capacity with a peculiar potential in tumor initiation, progression, metastasis, heterogeneity, recurrence, radiotherapy and drug resistance. However, HERVs role in CSCs biology is still not fully elucidated. In this regard, CD133 is a widely recognized marker of CSCs, and our group demonstrated, for the first time, the requirement of HERV-K activation to expand and maintain a CD133+ melanoma cell subpopulation with stemness features in response to microenvironmental modifications. The review will discuss HERVs expression as cancer hallmark, with particular focus on their role in the regulation of cancer stemness features and the potential involvement as targets for therapy.
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Affiliation(s)
- Claudia Matteucci
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Via Montpellier, 1, 00133, Rome, Italy.
| | - Emanuela Balestrieri
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Via Montpellier, 1, 00133, Rome, Italy
| | - Ayele Argaw-Denboba
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Via Montpellier, 1, 00133, Rome, Italy; European Molecular Biology Laboratory (EMBL), Adriano Buzzati-Traverso Campus, Monterotondo, Rome, Italy
| | - Paola Sinibaldi-Vallebona
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Via Montpellier, 1, 00133, Rome, Italy; Institute of Translational Pharmacology, National Research Council, Via Fosso del Cavaliere, 100, 00133, Rome, Italy
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44
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Mayer J, Harz C, Sanchez L, Pereira GC, Maldener E, Heras SR, Ostrow LW, Ravits J, Batra R, Meese E, García-Pérez JL, Goodier JL. Transcriptional profiling of HERV-K(HML-2) in amyotrophic lateral sclerosis and potential implications for expression of HML-2 proteins. Mol Neurodegener 2018; 13:39. [PMID: 30068350 PMCID: PMC6091006 DOI: 10.1186/s13024-018-0275-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 07/23/2018] [Indexed: 12/12/2022] Open
Abstract
Background Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder. About 90% of ALS cases are without a known genetic cause. The human endogenous retrovirus multi-copy HERV-K(HML-2) group was recently reported to potentially contribute to neurodegeneration and disease pathogenesis in ALS because of transcriptional upregulation and toxic effects of HML-2 Envelope (Env) protein. Env and other proteins are encoded by some transcriptionally active HML-2 loci. However, more detailed information is required regarding which HML-2 loci are transcribed in ALS, which of their proteins are expressed, and differences between the disease and non-disease states. Methods For brain and spinal cord tissue samples from ALS patients and controls, we identified transcribed HML-2 loci by generating and mapping HML-2-specific cDNA sequences. We predicted expression of HML-2 env gene-derived proteins based on the observed cDNA sequences. Furthermore, we determined overall HML-2 transcript levels by RT-qPCR and investigated presence of HML-2 Env protein in ALS and control tissue samples by Western blotting. Results We identified 24 different transcribed HML-2 loci. Some of those loci are transcribed at relatively high levels. However, significant differences in HML-2 loci transcriptional activities were not seen when comparing ALS and controls. Likewise, overall HML-2 transcript levels, as determined by RT-qPCR, were not significantly different between ALS and controls. Indeed, we were unable to detect full-length HML-2 Env protein in ALS and control tissue samples despite reasonable sensitivity. Rather our analyses suggest that a number of HML-2 protein variants other than full-length Env may potentially be expressed in ALS patients. Conclusions Our results expand and refine recent publications on HERV-K(HML-2) and ALS. Some of our results are in conflict with recent findings and call for further specific analyses. Our profiling of HML-2 transcription in ALS opens up the possibility that HML-2 proteins other than canonical full-length Env may have to be considered when studying the role of HML-2 in ALS disease. Electronic supplementary material The online version of this article (10.1186/s13024-018-0275-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jens Mayer
- Department of Human Genetics, University of Saarland, Homburg, Germany.
| | - Christian Harz
- Department of Human Genetics, University of Saarland, Homburg, Germany
| | - Laura Sanchez
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
| | - Gavin C Pereira
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Esther Maldener
- Department of Human Genetics, University of Saarland, Homburg, Germany
| | - Sara R Heras
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain.,Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071, Granada, Spain
| | - Lyle W Ostrow
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 28217, USA
| | - John Ravits
- Department of Neurosciences, School of Medicine, UCSD, San Diego, CA, USA
| | - Ranjan Batra
- Department of Neurosciences, School of Medicine, UCSD, San Diego, CA, USA
| | - Eckart Meese
- Department of Human Genetics, University of Saarland, Homburg, Germany
| | - Jose Luis García-Pérez
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain.,MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - John L Goodier
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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45
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Balestrieri E, Argaw-Denboba A, Gambacurta A, Cipriani C, Bei R, Serafino A, Sinibaldi-Vallebona P, Matteucci C. Human Endogenous Retrovirus K in the Crosstalk Between Cancer Cells Microenvironment and Plasticity: A New Perspective for Combination Therapy. Front Microbiol 2018; 9:1448. [PMID: 30013542 PMCID: PMC6036167 DOI: 10.3389/fmicb.2018.01448] [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: 02/28/2018] [Accepted: 06/11/2018] [Indexed: 12/24/2022] Open
Abstract
Abnormal activation of human endogenous retroviruses (HERVs) has been associated with several diseases such as cancer, autoimmunity, and neurological disorders. In particular, in cancer HERV activity and expression have been specifically associated with tumor aggressiveness and patient outcomes. Cancer cell aggressiveness is intimately linked to the acquisition of peculiar plasticity and heterogeneity based on cell stemness features, as well as on the crosstalk between cancer cells and the microenvironment. The latter is a driving factor in the acquisition of aggressive phenotypes, associated with metastasis and resistance to conventional cancer therapies. Remarkably, in different cell types and stages of development, HERV expression is mainly regulated by epigenetic mechanisms and is subjected to a very precise temporal and spatial regulation according to the surrounding microenvironment. Focusing on our research experience with HERV-K involvement in the aggressiveness and plasticity of melanoma cells, this perspective aims to highlight the role of HERV-K in the crosstalk between cancer cells and the tumor microenvironment. The implications for a combination therapy targeted at HERVs with standard approaches are discussed.
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Affiliation(s)
- Emanuela Balestrieri
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Rome, Italy
| | - Ayele Argaw-Denboba
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Rome, Italy
| | - Alessandra Gambacurta
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Rome, Italy
| | - Chiara Cipriani
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Rome, Italy
| | - Roberto Bei
- Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - Annalucia Serafino
- Institute of Translational Pharmacology, National Research Council, Rome, Italy
| | - Paola Sinibaldi-Vallebona
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Rome, Italy.,Institute of Translational Pharmacology, National Research Council, Rome, Italy
| | - Claudia Matteucci
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata", Rome, Italy
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46
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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: 140] [Impact Index Per Article: 23.3] [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.
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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
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47
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Bannert N, Hofmann H, Block A, Hohn O. HERVs New Role in Cancer: From Accused Perpetrators to Cheerful Protectors. Front Microbiol 2018; 9:178. [PMID: 29487579 PMCID: PMC5816757 DOI: 10.3389/fmicb.2018.00178] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/25/2018] [Indexed: 02/02/2023] Open
Abstract
Initial indications that retroviruses are connected to neoplastic transformation were seen more than a century ago. This concept has also been tested for endogenized retroviruses (ERVs) that are abundantly expressed in many transformed cells. In healthy cells, ERV expression is commonly prevented by DNA methylation and other epigenetic control mechanisms. ERVs are remnants of former exogenous forms that invaded the germ line of the host and have since been vertically transmitted. Several examples of ERV-induced genomic recombination events and dysregulation of cellular genes that contribute to tumor formation have been well documented. Moreover, evidence is accumulating that certain ERV proteins have oncogenic properties. In contrast to these implications for supporting cancer induction, a recent string of papers has described favorable outcomes of increasing human ERV (HERV) RNA and DNA abundance by treatment of cancer cells with methyltransferase inhibitors. Analogous to an infecting agent, the ERV-derived nucleic acids are sensed in the cytoplasm and activate innate immune responses that drive the tumor cell into apoptosis. This "viral mimicry" induced by epigenetic drugs might offer novel therapeutic approaches to help target cancer cells that are normally difficult to treat using standard chemotherapy. In this review, we discuss both the detrimental and the new beneficial role of HERV reactivation in terms of its implications for cancer.
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Affiliation(s)
- Norbert Bannert
- HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
| | - Henning Hofmann
- HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
| | - Adriana Block
- HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
| | - Oliver Hohn
- HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
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48
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Platt RN, Vandewege MW, Ray DA. Mammalian transposable elements and their impacts on genome evolution. Chromosome Res 2018; 26:25-43. [PMID: 29392473 PMCID: PMC5857283 DOI: 10.1007/s10577-017-9570-z] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 12/12/2017] [Accepted: 12/28/2017] [Indexed: 12/22/2022]
Abstract
Transposable elements (TEs) are genetic elements with the ability to mobilize and replicate themselves in a genome. Mammalian genomes are dominated by TEs, which can reach copy numbers in the hundreds of thousands. As a result, TEs have had significant impacts on mammalian evolution. Here we summarize the current understanding of TE content in mammal genomes and find that, with a few exceptions, most fall within a predictable range of observations. First, one third to one half of the genome is derived from TEs. Second, most mammalian genomes are dominated by LINE and SINE retrotransposons, more limited LTR retrotransposons, and minimal DNA transposon accumulation. Third, most mammal genome contains at least one family of actively accumulating retrotransposon. Finally, horizontal transfer of TEs among lineages is rare. TE exaptation events are being recognized with increasing frequency. Despite these beneficial aspects of TE content and activity, the majority of TE insertions are neutral or deleterious. To limit the deleterious effects of TE proliferation, the genome has evolved several defense mechanisms that act at the epigenetic, transcriptional, and post-transcriptional levels. The interaction between TEs and these defense mechanisms has led to an evolutionary arms race where TEs are suppressed, evolve to escape suppression, then are suppressed again as the defense mechanisms undergo compensatory change. The result is complex and constantly evolving interactions between TEs and host genomes.
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Affiliation(s)
- Roy N Platt
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.
| | | | - David A Ray
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
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Susceptibility of Human Endogenous Retrovirus Type K to Reverse Transcriptase Inhibitors. J Virol 2017; 91:JVI.01309-17. [PMID: 28931682 DOI: 10.1128/jvi.01309-17] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 09/14/2017] [Indexed: 12/13/2022] Open
Abstract
Human endogenous retroviruses (HERVs) make up 8% of the human genome. The HERV type K (HERV-K) HML-2 (HK2) family contains proviruses that are the most recent entrants into the human germ line and are transcriptionally active. In HIV-1 infection and cancer, HK2 genes produce retroviral particles that appear to be infectious, yet the replication capacity of these viruses and potential pathogenicity has been difficult to ascertain. In this report, we screened the efficacy of commercially available reverse transcriptase inhibitors (RTIs) at inhibiting the enzymatic activity of HK2 RT and HK2 genomic replication. Interestingly, only one provirus, K103, was found to encode a functional RT among those examined. Several nucleoside analogue RTIs (NRTIs) blocked K103 RT activity and consistently inhibited the replication of HK2 genomes. The NRTIs zidovudine (AZT), stavudine (d4T), didanosine (ddI), and lamivudine (3TC), and the nucleotide RTI inhibitor tenofovir (TDF), show efficacy in blocking K103 RT. HIV-1-specific nonnucleoside RTIs (NNRTIs), protease inhibitors (PIs), and integrase inhibitors (IIs) did not affect HK2, except for the NNRTI etravirine (ETV). The inhibition of HK2 infectivity by NRTIs appears to take place at either the reverse transcription step of the viral genome prior to HK2 viral particle formation and/or in the infected cells. Inhibition of HK2 by these drugs will be useful in suppressing HK2 infectivity if these viruses prove to be pathogenic in cancer, neurological disorders, or other diseases associated with HK2. The present studies also elucidate a key aspect of the life cycle of HK2, specifically addressing how they do, and/or did, replicate.IMPORTANCE Endogenous retroviruses are relics of ancestral virus infections in the human genome. The most recent of these infections was caused by HK2. While HK2 often remains silent in the genome, this group of viruses is activated in HIV-1-infected and cancer cells. Recent evidence suggests that these viruses are infectious, and the potential exists for HK2 to contribute to disease. We show that HK2, and specifically the enzyme that mediates virus replication, can be inhibited by a panel of drugs that are commercially available. We show that several drugs block HK2 with different efficacies. The inhibition of HK2 replication by antiretroviral drugs appears to occur in the virus itself as well as after infection of cells. Therefore, these drugs might prove to be an effective treatment by suppressing HK2 infectivity in diseases where these viruses have been implicated, such as cancer and neurological syndromes.
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Grandi N, Cadeddu M, Pisano MP, Esposito F, Blomberg J, Tramontano E. Identification of a novel HERV-K(HML10): comprehensive characterization and comparative analysis in non-human primates provide insights about HML10 proviruses structure and diffusion. Mob DNA 2017; 8:15. [PMID: 29118853 PMCID: PMC5667498 DOI: 10.1186/s13100-017-0099-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/24/2017] [Indexed: 11/23/2022] Open
Abstract
Background About half of the human genome is constituted of transposable elements, including human endogenous retroviruses (HERV). HERV sequences represent the 8% of our genetic material, deriving from exogenous infections occurred millions of years ago in the germ line cells and being inherited by the offspring in a Mendelian fashion. HERV-K elements (classified as HML1–10) are among the most studied HERV groups, especially due to their possible correlation with human diseases. In particular, the HML10 group was reported to be upregulated in persistent HIV-1 infected cells as well as in tumor cells and samples, and proposed to have a role in the control of host genes expression. An individual HERV-K(HML10) member within the major histocompatibility complex C4 gene has even been studied for its possible contribution to type 1 diabetes susceptibility. Following a first characterization of the HML10 group at the genomic level, performed with the innovative software RetroTector, we have characterized in detail the 8 previously identified HML10 sequences present in the human genome, and an additional HML10 partial provirus in chromosome 1p22.2 that is reported here for the first time. Results Using a combined approach based on RetroTector software and a traditional Genome Browser Blat search, we identified a novel HERV-K(HML10) sequence in addition to the eight previously reported in the human genome GRCh37/hg19 assembly. We fully characterized the nine HML10 sequences at the genomic level, including their classification in two types based on both structural and phylogenetic characteristics, a detailed analysis of each HML10 nucleotide sequence, the first description of the presence of an Env Rec domain in the type II HML10, the estimated time of integration of individual members and the comparative map of the HML10 proviruses in non-human primates. Conclusions We performed an unambiguous and exhaustive analysis of the nine HML10 sequences present in GRCh37/hg19 assembly, useful to increase the knowledge of the group’s contribution to the human genome and laying the foundation for a better understanding of the potential physiological effects and the tentative correlation of these sequences with human pathogenesis. Electronic supplementary material The online version of this article (10.1186/s13100-017-0099-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nicole Grandi
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Marta Cadeddu
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Maria Paola Pisano
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Francesca Esposito
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Jonas Blomberg
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Enzo Tramontano
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy.,Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche (CNR), Monserrato, Cagliari, Italy
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