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Shin W, Mun S, Han K. Human Endogenous Retrovirus-K (HML-2)-Related Genetic Variation: Human Genome Diversity and Disease. Genes (Basel) 2023; 14:2150. [PMID: 38136972 PMCID: PMC10742618 DOI: 10.3390/genes14122150] [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: 10/25/2023] [Revised: 11/23/2023] [Accepted: 11/26/2023] [Indexed: 12/24/2023] Open
Abstract
Human endogenous retroviruses (HERVs) comprise a significant portion of the human genome, making up roughly 8%, a notable comparison to the 2-3% represented by coding sequences. Numerous studies have underscored the critical role and importance of HERVs, highlighting their diverse and extensive influence on the evolution of the human genome and establishing their complex correlation with various diseases. Among HERVs, the HERV-K (HML-2) subfamily has recently attracted significant attention, integrating into the human genome after the divergence between humans and chimpanzees. Its insertion in the human genome has received considerable attention due to its structural and functional characteristics and the time of insertion. Originating from ancient exogenous retroviruses, these elements succeeded in infecting germ cells, enabling vertical transmission and existing as proviruses within the genome. Remarkably, these sequences have retained the capacity to form complete viral sequences, exhibiting activity in transcription and translation. The HERV-K (HML-2) subfamily is the subject of active debate about its potential positive or negative effects on human genome evolution and various pathologies. This review summarizes the variation, regulation, and diseases in human genome evolution arising from the influence of HERV-K (HML-2).
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Affiliation(s)
- Wonseok Shin
- NGS Clinical Laboratory, Division of Cancer Research, Dankook University Hospital, Cheonan 31116, Republic of Korea;
- Smart Animal Bio Institute, Dankook University, Cheonan 31116, Republic of Korea;
| | - Seyoung Mun
- Smart Animal Bio Institute, Dankook University, Cheonan 31116, Republic of Korea;
- College of Science & Technology, Dankook University, Cheonan 31116, Republic of Korea
- Center for Bio-Medical Engineering Core Facility, Dankook University, Cheonan 31116, Republic of Korea
| | - Kyudong Han
- Smart Animal Bio Institute, Dankook University, Cheonan 31116, Republic of Korea;
- Center for Bio-Medical Engineering Core Facility, Dankook University, Cheonan 31116, Republic of Korea
- Department of Microbiology, College of Science & Technology, Dankook University, Cheonan 31116, Republic of Korea
- Department of Bioconvergence Engineering, Dankook University, Yongin 16890, Republic of Korea
- R&D Center, HuNBiome Co., Ltd., Seoul 08507, Republic of Korea
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Marongiu L, Landry JJM, Rausch T, Abba ML, Delecluse S, Delecluse H, Allgayer H. Metagenomic analysis of primary colorectal carcinomas and their metastases identifies potential microbial risk factors. Mol Oncol 2021; 15:3363-3384. [PMID: 34328665 PMCID: PMC8637581 DOI: 10.1002/1878-0261.13070] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/09/2021] [Accepted: 07/29/2021] [Indexed: 12/18/2022] Open
Abstract
The paucity of microbiome studies at intestinal tissues has contributed to a yet limited understanding of potential viral and bacterial cofactors of colorectal cancer (CRC) carcinogenesis or progression. We analysed whole-genome sequences of CRC primary tumours, their corresponding metastases and matched normal tissue for sequences of viral, phage and bacterial species. Bacteriome analysis showed Fusobacterium nucleatum, Streptococcus sanguinis, F. Hwasookii, Anaerococcus mediterraneensis and further species enriched in primary CRCs. The primary CRC of one patient was enriched for F. alocis, S. anginosus, Parvimonas micra and Gemella sp. 948. Enrichment of Escherichia coli strains IAI1, SE11, K-12 and M8 was observed in metastases together with coliphages enterobacteria phage φ80 and Escherichia phage VT2φ_272. Virome analysis showed that phages were the most preponderant viral species (46%), the main families being Myoviridae, Siphoviridae and Podoviridae. Primary CRCs were enriched for bacteriophages, showing five phages (Enterobacteria, Bacillus, Proteus, Streptococcus phages) together with their pathogenic hosts in contrast to normal tissues. The most frequently detected, and Blast-confirmed, viruses included human endogenous retrovirus K113, human herpesviruses 7 and 6B, Megavirus chilensis, cytomegalovirus (CMV) and Epstein-Barr virus (EBV), with one patient showing EBV enrichment in primary tumour and metastases. EBV was PCR-validated in 80 pairs of CRC primary tumour and their corresponding normal tissues; in 21 of these pairs (26.3%), it was detectable in primary tumours only. The number of viral species was increased and bacterial species decreased in CRCs compared with normal tissues, and we could discriminate primary CRCs from metastases and normal tissues by applying the Hutcheson t-test on the Shannon indices based on viral and bacterial species. Taken together, our results descriptively support hypotheses on microorganisms as potential (co)risk factors of CRC and extend putative suggestions on critical microbiome species in CRC metastasis.
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Affiliation(s)
- Luigi Marongiu
- Department of Experimental Surgery – Cancer MetastasisMedical Faculty MannheimRuprecht‐Karls University of HeidelbergMannheimGermany
| | | | - Tobias Rausch
- Genomics Core FacilityEuropean Molecular Biology Laboratory (EMBL)HeidelbergGermany
| | - Mohammed L. Abba
- Department of Experimental Surgery – Cancer MetastasisMedical Faculty MannheimRuprecht‐Karls University of HeidelbergMannheimGermany
| | | | | | - Heike Allgayer
- Department of Experimental Surgery – Cancer MetastasisMedical Faculty MannheimRuprecht‐Karls University of HeidelbergMannheimGermany
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SMARCB1 deletion in atypical teratoid rhabdoid tumors results in human endogenous retrovirus K (HML-2) expression. Sci Rep 2021; 11:12893. [PMID: 34145313 PMCID: PMC8213802 DOI: 10.1038/s41598-021-92223-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 05/27/2021] [Indexed: 12/19/2022] Open
Abstract
Atypical Teratoid Rhabdoid Tumor (AT/RT) is a rare pediatric central nervous system cancer often characterized by deletion or mutation of SMARCB1, a tumor suppressor gene. In this study, we found that SMARCB1 regulates Human Endogenous Retrovirus K (HERV-K, subtype HML-2) expression. HML-2 is a repetitive element scattered throughout the human genome, encoding several intact viral proteins that have been associated with stem cell maintenance and tumorigenesis. We found HML-2 env expression in both the intracellular and extracellular compartments in all AT/RT cell lines (n = 4) and in 95% of AT/RT patient tissues (n = 37) evaluated. SMARCB1 knock-down in neural stem cells (NSCs) led to an upregulation of HML-2 transcription. We found that SMARCB1 binds adjacent to the HML-2 promoter, repressing its transcription via chromatin immunoprecipitation; restoration of SMARCB1 expression in AT/RT cell lines significantly downregulated HML-2 expression. Further, targeted downregulation of HML-2 transcription via CRISPR-dCas9 coupled with suppressor proteins led to cellular dispersion, decreased proliferation, and cell death in vitro. HML-2 knock-down with shRNA, siRNA, and CRISPR-dCas9 significantly decreased Ras expression as measured by qRT-PCR, suggesting that HML-2 modulates MAPK/ERK signaling in AT/RT cells. Overexpression of NRAS was sufficient to restore cellular proliferation, and MYC, a transcription factor downstream of NRAS, was bound to the HERV-K LTR significantly more in the absence of SMARCB1 expression in AT/RT cells. We show a mechanism by which these undifferentiated tumors remain pluripotent, and we demonstrate that their formation is aided by aberrant HML-2 activation, which is dependent on SMARCB1 and its interaction with MYC.
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Yegin Z, Avsar C, Sarisoy G. Frequency of retrotransposon human endogenous retrovirus-K113 and a preliminary analysis of some microbial clues in bipolar disorder. Future Microbiol 2020; 15:1621-1629. [PMID: 33215524 DOI: 10.2217/fmb-2020-0166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: The aim of our study was to investigate whether the retrotransposon human endogenous retrovirus (HERV)-K113 could be related with bipolar disorder or not. As a second and a preliminary aim, we also conducted bacterial screening in whole blood in a limited number of samples. Patients & methods: Three separate PCR reactions including the preintegration sites and sites within the viral sequences were performed for HERV-K113 detection. Bacterial screening was performed with SSCP/sequencing analysis. Results & conclusion: No difference was observed in terms of the frequency of retrotransposon HERV-K113 in Turkish bipolar disorder patients and healthy controls. SSCP/sequencing and alignment analysis for bacterial screening reflected the possible presence of different bacteria. We strongly recommend the broadened retrotransposon and microbial diversity analyses in bipolar disorder for future studies.
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Affiliation(s)
- Zeynep Yegin
- Medical Laboratory Techniques Program, Vocational School of Health Services, Sinop University, Sinop, Turkey
| | - Cumhur Avsar
- Department of Biology, Faculty of Arts & Sciences, Sinop University, Sinop, Turkey
| | - Gokhan Sarisoy
- Department of Psychiatry, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
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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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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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Kaplan MH, Contreras-Galindo R, Jiagge E, Merajver SD, Newman L, Bigman G, Dosik MH, Palapattu GS, Siddiqui J, Chinnaiyan AM, Adebamowo S, Adebamowo C. Is the HERV-K HML-2 Xq21.33, an endogenous retrovirus mutated by gene conversion of chromosome X in a subset of African populations, associated with human breast cancer? Infect Agent Cancer 2020; 15:19. [PMID: 32165916 PMCID: PMC7060579 DOI: 10.1186/s13027-020-00284-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 02/25/2020] [Indexed: 02/06/2023] Open
Abstract
The human endogenous retroviruses HERV-K HML-2 have been considered a possible cause of human breast cancer (BrC). A HERV-K HML-2 fully intact provirus Xq21.33 was recently identified in some West African people. We used PCR technology to search for the Xq21.33 provirus in DNA from Nigerian women with BrC and controls. to see if Xq21.33 plays any role in predisposing to BrC. This provirus was detected in 27 of 216 (12.5%) women with BrC and in 22 of 219 (10.0%) controls. These results were not statistically significant. The prevalence of provirus in premenopausal control women 44 years or younger [18/157 (11.46%)} vs women with BrC [12/117 (10.26%)] showed no statistical difference. The prevalence of virus in postmenopausal control women > 45 yrs. was 7.4% (4/54) vs 15.31% (15/98) in postmenopausal women with BrC. These changes were not statistically significant at <.05, but the actual p value of <.0.079, suggests that Xq21.33 might play some role in predisposing to BrC in postmenopausal women. Provirus was present in Ghanaian women (6/87), in 1/6 Pygmy populations and in African American men (4/45) and women (6/68), but not in any Caucasian women (0/109). Two BrC cell lines (HCC 70 and DT22) from African American women had Xq21.33. Env regions of the virus which differed by 2-3 SNPs did not alter the protein sequence of the virus. SNP at 5730 and 8529 were seen in all persons with provirus, while 54% had an additional SNP at 7596.Two Nigerian women and 2 Ghanaian women had additional unusual SNPs. Homozygosity was seen in (5/27) BrC and (2/22) control women. The genetic variation and homozygosity patterns suggested that there was gene conversion of this X chromosome associated virus. The suggestive finding in this preliminary data of possible increased prevalence of Xq21.33 provirus in post-menopausal Nigerian women with BrC should be clarified by a more statistically powered study sample to see if postmenopausal African and/or African American women carriers of Xq21.33 might show increased risk of BrC. The implication of finding such a link would be the development of antiretroviral drugs that might aid in preventing BrC in Xq21.33+ women.
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Affiliation(s)
- Mark H. Kaplan
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109 USA
| | | | - Evelyn Jiagge
- Henry Ford Cancer Institute, Henry Ford Health System, Detroit, Mi USA
| | - Sofia D. Merajver
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109 USA
| | - Lisa Newman
- Weill Cornell Medicine, New York, NY 10021 USA
| | - Galya Bigman
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Michael H. Dosik
- Department of Internal Medicine, Renaissance School of Medicine at Stony Brook Medical, Stony Brook, NY 11794 USA
| | | | - Javed Siddiqui
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109 USA
- Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Arul M. Chinnaiyan
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109 USA
- Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Sally Adebamowo
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Clement Adebamowo
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201 USA
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109 USA
- Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201 USA
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Yandım C, Karakülah G. Dysregulated expression of repetitive DNA in ER+/HER2- breast cancer. Cancer Genet 2019; 239:36-45. [PMID: 31536958 DOI: 10.1016/j.cancergen.2019.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/03/2019] [Accepted: 09/05/2019] [Indexed: 12/12/2022]
Abstract
Limited studies on breast cancer indicated pathogenic changes in the expressions of some repeat elements. A global analysis was much needed within this context to distinguish the most significant repeats from more than a thousand repeat motifs. Utilising a previously presented RNA-seq dataset, we studied expression changes of all repeats in ER+/HER2- human breast tumour samples obtained from 22 patients in comparison to matched normal tissues. Fifty six (56) repeat subtypes including satellites and transposons were found to be differentially expressed and most of them were novel for breast cancer. HERVKC4-int and HERV1_LTRc, whose expressions correlated well with that of the estrogen receptor gene ESR1, were upregulated at the highest level. REP522 and D20S16 satellites were also significantly upregulated along with insignificant increases in the expressions of other satellites including HSATI and BSR/beta. Interestingly, expressions of REP522 and D20S16 correlated with many key breast cancer pathway (e.g. BRCA1, BRCA2, AKT1, MTOR, KRAS) and survival genes; possibly highlighting their importance in the carcinogenesis of breast. Additional differentially expressed elements such as L1P and various MER transposons also exhibited a similar pattern. Finally, our repeat enrichment analysis on the promoters of differentially expressed genes revealed further links between additional repeats and nearby genes.
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Affiliation(s)
- Cihangir Yandım
- İzmir University of Economics, Faculty of Engineering, Department of Genetics and Bioengineering, 35330, Balçova, İzmir, Turkey; İzmir Biomedicine and Genome Center (IBG), Dokuz Eylül University Health Campus, 35340, İnciraltı, İzmir, Turkey
| | - Gökhan Karakülah
- İzmir Biomedicine and Genome Center (IBG), Dokuz Eylül University Health Campus, 35340, İnciraltı, İzmir, Turkey; İzmir International Biomedicine and Genome Institute (iBG-İzmir), Dokuz Eylül University, 35340, İnciraltı, İzmir, Turkey.
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Ellsworth DL, Turner CE, Ellsworth RE. A Review of the Hereditary Component of Triple Negative Breast Cancer: High- and Moderate-Penetrance Breast Cancer Genes, Low-Penetrance Loci, and the Role of Nontraditional Genetic Elements. JOURNAL OF ONCOLOGY 2019; 2019:4382606. [PMID: 31379942 PMCID: PMC6652078 DOI: 10.1155/2019/4382606] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/23/2019] [Indexed: 12/31/2022]
Abstract
Triple negative breast cancer (TNBC), representing 10-15% of breast tumors diagnosed each year, is a clinically defined subtype of breast cancer associated with poor prognosis. The higher incidence of TNBC in certain populations such as young women and/or women of African ancestry and a unique pathological phenotype shared between TNBC and BRCA1-deficient tumors suggest that TNBC may be inherited through germline mutations. In this article, we describe genes and genetic elements, beyond BRCA1 and BRCA2, which have been associated with increased risk of TNBC. Multigene panel testing has identified high- and moderate-penetrance cancer predisposition genes associated with increased risk for TNBC. Development of large-scale genome-wide SNP assays coupled with genome-wide association studies (GWAS) has led to the discovery of low-penetrance TNBC-associated loci. Next-generation sequencing has identified variants in noncoding RNAs, viral integration sites, and genes in underexplored regions of the human genome that may contribute to the genetic underpinnings of TNBC. Advances in our understanding of the genetics of TNBC are driving improvements in risk assessment and patient management.
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Affiliation(s)
| | - Clesson E. Turner
- Murtha Cancer Center/Research Program, Uniformed Services University and Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Rachel E. Ellsworth
- Murtha Cancer Center/Research Program, Uniformed Services University and Walter Reed National Military Medical Center, Bethesda, MD, USA
- Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
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Close to the Bedside: A Systematic Review of Endogenous Retroviruses and Their Impact in Oncology. J Surg Res 2019; 240:145-155. [PMID: 30933828 DOI: 10.1016/j.jss.2019.02.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 12/22/2018] [Accepted: 02/04/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Human endogenous retroviruses (HERVs) are genetic elements in the human genome, which resulted from ancient retroviral germline infections. HERVs have strong transcriptional promoters and enhancers that affect a cell's transcriptome. They also encode proteins that can exert effects in human cells. This review examines how our increased understanding of HERVs have led to their potential use as biomarkers and immunologic targets. MATERIAL AND METHODS PubMed/Medline, Embase, Web of Science, and Cochrane databases were used in a systematic search to identify all articles studying the potential impact of HERVs on surgical diseases. The search included studies that involved clinical patient samples in diseases including cancer, inflammatory conditions, and autoimmune disease. Articles focused on conditions not routinely managed by surgeons were excluded. RESULTS Eighty six articles met inclusion and quality criteria for this review and were included. Breast cancer and melanoma have robust evidence regarding the use of HERVs as potential tumor markers and immunologic targets. Reported evidence of the activity of HERVs in colorectal cancer, pancreatic cancer, hepatocellular cancer, prostate and ovarian cancer, germ cell tumors as well as idiopathic pulmonary hypertension, and the inflammatory response in burns was also reviewed. CONCLUSIONS Increasingly convincing evidence indicates that HERVs may play a role in solid organ malignancy and present important biomarkers or immunologic targets in multiple cancers. Innovative investigation of HERVs is a valuable focus of translational research and can deepen our understanding of cellular physiology and the effects of endogenous retroviruses on human biology. As strategies for treatment continue to focus on genome-based interventions, understanding the impact of endogenous retroviruses on human disease will be critical.
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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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Tartaglione AM, Cipriani C, Chiarotti F, Perrone B, Balestrieri E, Matteucci C, Sinibaldi-Vallebona P, Calamandrei G, Ricceri L. Early Behavioral Alterations and Increased Expression of Endogenous Retroviruses Are Inherited Across Generations in Mice Prenatally Exposed to Valproic Acid. Mol Neurobiol 2018; 56:3736-3750. [DOI: 10.1007/s12035-018-1328-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 08/22/2018] [Indexed: 12/12/2022]
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Montesion M, Williams ZH, Subramanian RP, Kuperwasser C, Coffin JM. Promoter expression of HERV-K (HML-2) provirus-derived sequences is related to LTR sequence variation and polymorphic transcription factor binding sites. Retrovirology 2018; 15:57. [PMID: 30126415 PMCID: PMC6102855 DOI: 10.1186/s12977-018-0441-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 08/13/2018] [Indexed: 12/29/2022] Open
Abstract
Background Increased transcription of the human endogenous retrovirus group HERV-K (HML-2) is often seen during disease. Although the mechanism of its tissue-specific activation is unclear, research shows that LTR CpG hypomethylation alone is not sufficient to induce its promoter activity and that the transcriptional milieu of a malignant cell contributes, at least partly, to differential HML-2 expression. Results We analyzed the relationship between LTR sequence variation and promoter expression patterns in human breast cancer cell lines, finding them to be positively correlated. In particular, two proviruses (3q12.3 and 11p15.4) displayed increased activity in almost all tumorigenic cell lines sampled. Using a transcription factor binding site prediction algorithm, we identified two unique binding sites in each 5′ LTR that appeared to be associated with inducing promoter activity during neoplasia. Genomic analysis of the homologous proviruses in several non-human primates indicated post-integration genetic drift in two transcription factor binding sites, away from the ancestral sequence and towards the active form. Based on the sequences of 2504 individuals from the 1000 Genomes Project, the active form of the 11p15.4 site was found to be polymorphic within the human population, with an allele frequency of 51%, whereas the activating mutation in the 3q12.3 provirus was fixed in humans but not present in the orthologous provirus in chimpanzees or gorillas. Conclusions These data suggest that stage-specific transcription factors at least partly contribute to LTR promoter activity during transformation and that, in some cases, transcription factor binding site polymorphisms may be responsible for the differential HML-2 expression often seen between individuals. Electronic supplementary material The online version of this article (10.1186/s12977-018-0441-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Meagan Montesion
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.,Foundation Medicine, Inc., Cambridge, MA, USA
| | - Zachary H Williams
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - Ravi P Subramanian
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.,Excerpta Medica, New York, NY, USA
| | - Charlotte Kuperwasser
- Department of Developmental, Chemical, and Molecular Biology, Tufts University School of Medicine, Boston, MA, USA.,Raymond and Beverly Sackler Convergence Laboratory, Tufts University School of Medicine, Boston, MA, USA
| | - John M Coffin
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.
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14
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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: 61] [Impact Index Per Article: 10.2] [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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15
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Hanke K, Hohn O, Bannert N. HERV-K(HML-2), a seemingly silent subtenant - but still waters run deep. APMIS 2016; 124:67-87. [PMID: 26818263 DOI: 10.1111/apm.12475] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/12/2015] [Indexed: 01/26/2023]
Abstract
A large proportion of the human genome consists of endogenous retroviruses, some of which are well preserved, showing transcriptional activity, and expressing retroviral proteins. The HERV-K(HML-2) family represents the most intact members of these elements, with some having open and intact reading frames for viral proteins and the ability to form virus-like particles. Although generally suppressed in most healthy tissues by a variety of epigenetic processes and antiviral mechanisms, there is evidence that some members of this family are (at least partly) still active - particularly in certain stem cells and various tumors. This raises the possibility of their involvement in tumor induction or in developmental processes. In recent years, many new insights into this fascinating field have been attained, and this review focuses on new discoveries about coevolutionary events and intracellular defense mechanisms against HERV-K(HML-2) activity. We also describe what might occur when these mechanisms fail or become modulated by viral proteins or other viruses and discuss the new vistas opened up by the reconstitution of ancestral viral proteins and even complete HML-2 viruses.
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Affiliation(s)
- Kirsten Hanke
- Department HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
| | - Oliver Hohn
- Department HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
| | - Norbert Bannert
- Department HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
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16
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Sistiaga-Poveda M, Larruskain A, Mateo-Abad M, Jugo BM. Lack of association between polymorphic copies of endogenous Jaagsiekte sheep retrovirus (enJSRVs) and Ovine Pulmonary Adenocarcinoma. Vet Microbiol 2016; 185:49-55. [PMID: 26931391 DOI: 10.1016/j.vetmic.2016.01.019] [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: 09/23/2015] [Revised: 01/18/2016] [Accepted: 01/25/2016] [Indexed: 10/22/2022]
Abstract
Ovine Pulmonary Adenocarcinoma (OPA) is a retrovirus-induced lung tumor of sheep, goat and mouflon, and its etiologic agent, Jaagsiekte sheep retrovirus (JSRV) is the only virus known to cause a naturally occurred lung adenocarcinoma. The oncogenic JSRV has several endogenous counterparts termed enJSRVs, some of which have been shown to interfere with JSRV replication at early and late stages of the retroviral cycle inhibiting JSRV exit from the cell, and thus, protecting sheep against the infection. In this work, Latxa sheep breed animals were classified depending on the presence/absence of OPA-characteristic clinical lesions in the lung. Using a PCR genotyping method and a logistic regression-based association study, five polymorphic enJSRV copies were analyzed in 49 OPA positive sheep and 124 control individuals. Our results showed that the frequency of the provirus enJSRV-16 is much higher in Latxa sheep breed than in other breeds, suggesting a recent proliferation of this provirus in the studied breed. However, no polymorphic enJSRV was found to be statistically associated with the susceptibility/resistance to OPA development.
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Affiliation(s)
- Maialen Sistiaga-Poveda
- Genetics, Physical Anthropology and Animal Physiology Department, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Amaia Larruskain
- Genetics, Physical Anthropology and Animal Physiology Department, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Maider Mateo-Abad
- Applied Mathematics, Statistics and Operative Research Department, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Begoña M Jugo
- Genetics, Physical Anthropology and Animal Physiology Department, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain.
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17
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Wildschutte JH, Ram D, Subramanian R, Stevens VL, Coffin JM. The distribution of insertionally polymorphic endogenous retroviruses in breast cancer patients and cancer-free controls. Retrovirology 2014; 11:62. [PMID: 25112280 PMCID: PMC4149278 DOI: 10.1186/s12977-014-0062-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/18/2014] [Indexed: 12/31/2022] Open
Abstract
Background Integration of retroviral DNA into a germ cell can result in a provirus that is transmitted vertically to the host’s offspring. In humans, such endogenous retroviruses (HERVs) comprise >8% of the genome. The HERV-K(HML-2) proviruses consist of ~90 elements related to mouse mammary tumor virus, which causes breast cancer in mice. A subset of HERV-K(HML-2) proviruses has some or all genes intact, and even encodes functional proteins, though a replication competent copy has yet to be observed. More than 10% of HML-2 proviruses are human-specific, having integrated subsequent to the Homo-Pan divergence, and, of these, 11 are currently known to be polymorphic in integration site with variable frequencies among individuals. Increased expression of the most recent HML-2 proviruses has been observed in tissues and cell lines from several types of cancer, including breast cancer, for which expression may provide a meaningful marker of the disease. Results In this study, we performed a case–control analysis to investigate the possible relationship between the genome-wide presence of individual polymorphic HML-2 proviruses with the occurrence of breast cancer. For this purpose, we screened 50 genomic DNA samples from individuals diagnosed with breast cancer or without history of the disease (n = 25 per group) utilizing a combination of locus-specific PCR screening, in silico analysis of HML-2 content within the reference human genome sequence, and high-resolution genomic hybridization in semi-dried agarose. By implementing this strategy, we were able to analyze the distribution of both annotated and previously undescribed polymorphic HML-2 proviruses within our sample set, and to assess their possible association with disease outcome. Conclusions In a case–control analysis of 50 humans with regard to breast cancer diagnosis, we found no significant difference in the prevalence of proviruses between groups, suggesting common polymorphic HML-2 proviruses are not associated with breast cancer. Our findings indicate a higher level of putatively novel HML-2 sites within the population, providing support for additional recent insertion events, implying ongoing, yet rare, activities. These findings do not rule out either the possibility of involvement of such proviruses in a subset of breast cancers, or their possible utility as tissue-specific markers of disease.
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Affiliation(s)
| | | | | | | | - John M Coffin
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston 02111, MA, USA.
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18
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Downey RF, Sullivan FJ, Wang-Johanning F, Ambs S, Giles FJ, Glynn SA. Human endogenous retrovirus K and cancer: Innocent bystander or tumorigenic accomplice? Int J Cancer 2014; 137:1249-57. [PMID: 24890612 PMCID: PMC6264888 DOI: 10.1002/ijc.29003] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 05/02/2014] [Accepted: 05/09/2014] [Indexed: 12/20/2022]
Abstract
Harbored as relics of ancient germline infections, human endogenous retroviruses (HERVs) now constitute up to 8% of our genome. A proportion of this sequence has been co-opted for molecular and cellular processes, beneficial to human physiology, such as the fusogenic activity of the envelope protein, a vital component of placentogenesis. However, the discovery of high levels of HERV-K mRNA and protein and even virions in a wide array of cancers has revealed that HERV-K may be playing a more sinister role–a role as an etiological agent in cancer itself. Whether the presence of this retroviral material is simply an epiphenomenon, or an actual causative factor, is a hotly debated topic. This review will summarize the current state of knowledge regarding HERV-K and cancer and attempt to outline the potential mechanisms by which HERV-K could be involved in the onset and promotion of carcinogenesis.
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Affiliation(s)
- Ronan F Downey
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland
| | - Francis J Sullivan
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland.,Department of Radiation Oncology, Galway University Hospitals, Galway, Ireland
| | | | - Stefan Ambs
- Laboratory of Human Carcinogenesis, National Cancer Institute, Bethesda, MD
| | - Francis J Giles
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland.,HRB Clinical Research Facilities Galway & Dublin, National University of Ireland Galway and Trinity College Dublin, Galway, Ireland
| | - Sharon A Glynn
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland
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19
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20
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Zwolińska K, Knysz B, Gąsiorowski J, Pazgan-Simon M, Gładysz A, Sobczyński M, Piasecki E. Frequency of human endogenous retroviral sequences (HERV) K113 and K115 in the Polish population, and their effect on HIV infection. PLoS One 2013; 8:e77820. [PMID: 24204983 PMCID: PMC3810129 DOI: 10.1371/journal.pone.0077820] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 09/04/2013] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The human genome contains about 8% of endogenous retroviral sequences originated from germ cell infections by exogenous retroviruses during evolution. Most of those sequences are inactive because of accumulation of mutations but some of them are still capable to be transcribed and translated. The latter are insertionally polymorphic HERV-K113 and HERV-K115. It has been suggested that their presence and expression was connected with several human diseases. It is also believed that they could interfere with the replication cycle of exogenous retroviruses, including HIV. RESULTS Prevalence of endogenous retroviral sequences HERV-K113 and HERV-K115 was determined in the Polish population. The frequencies were found as 11.8% for HERV-K113 and 7.92% for HERV-K115. To verify the hypothesis that the presence of these HERVs sequences could affect susceptibility to HIV infection, comparison of a control group (HIV-negative, not exposed to HIV; n = 303) with HIV-positive patients (n = 470) and exposed but uninfected (EU) individuals (n = 121) was performed. Prevalence of HERV-K113 and HERV-K115 in the EU group was 8.26% and 5.71%, respectively. In the HIV(+) group we detected HERV-K113 sequences in 12.98% of the individuals and HERV-K115 sequences in 7.23% of the individuals. There were no statistically significant differences between groups studied. CONCLUSION The frequency of HERV-K113 and HERV-K115 sequences in Poland were found to be higher than usually shown for European populations. No relation between presence of the HERVs and HIV infection was detected.
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Affiliation(s)
- Katarzyna Zwolińska
- Laboratory of Virology, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland
- * E-mail:
| | - Brygida Knysz
- Department and Clinic of Infectious Diseases, Liver Diseases and Acquired Immune Deficiencies, Wrocław Medical University, Poland
| | - Jacek Gąsiorowski
- Department and Clinic of Infectious Diseases, Liver Diseases and Acquired Immune Deficiencies, Wrocław Medical University, Poland
| | - Monika Pazgan-Simon
- Department and Clinic of Infectious Diseases, Liver Diseases and Acquired Immune Deficiencies, Wrocław Medical University, Poland
| | - Andrzej Gładysz
- Department and Clinic of Infectious Diseases, Liver Diseases and Acquired Immune Deficiencies, Wrocław Medical University, Poland
| | - Maciej Sobczyński
- Department of Genomics, Faculty of Biotechnology, University of Wrocław, Poland
| | - Egbert Piasecki
- Laboratory of Virology, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland
- Institute of Chemistry, Environmental Protection and Biotechnology, Jan Długosz University, Częstochowa, Poland
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21
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Schmitt K, Reichrath J, Roesch A, Meese E, Mayer J. Transcriptional profiling of human endogenous retrovirus group HERV-K(HML-2) loci in melanoma. Genome Biol Evol 2013; 5:307-28. [PMID: 23338945 PMCID: PMC3590776 DOI: 10.1093/gbe/evt010] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Recent studies suggested a role for the human endogenous retrovirus (HERV) group HERV-K(HML-2) in melanoma because of upregulated transcription and expression of HERV-K(HML-2)-encoded proteins. Very little is known about which HML-2 loci are transcribed in melanoma. We assigned >1,400 HML-2 cDNA sequences generated from various melanoma and related samples to genomic HML-2 loci, identifying a total of 23 loci as transcribed. Transcription profiles of loci differed significantly between samples. One locus was found transcribed only in melanoma-derived samples but not in melanocytes and might represent a marker for melanoma. Several of the transcribed loci harbor ORFs for retroviral Gag and/or Env proteins. Env-encoding loci were transcribed only in melanoma. Specific investigation of rec and np9 transcripts indicated transcription of protein encoding loci in melanoma and melanocytes hinting at the relevance of Rec and Np9 in melanoma. UVB irradiation changed transcription profiles of loci and overall transcript levels decreased in melanoma and melanocytes. We further identified transcribed HML-2 loci formed by reverse transcription of spliced HML-2 transcripts by L1 machinery or in a retroviral fashion, with loci potentially encoding HML-2-like proteins. We reveal complex, sample-specific transcription of HML-2 loci in melanoma and related samples. Identified HML-2 loci and proteins encoded by those loci are particularly relevant for further studying the role of HML-2 in melanoma. Transcription of HERVs appears as a complex mechanism requiring specific studies to elucidate which HERV loci are transcribed and how transcribed HERVs may be involved in disease.
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Affiliation(s)
- Katja Schmitt
- Institute of Human Genetics, Medical Faculty, University of Saarland, Homburg/Saar, Germany
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22
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Yu HL, Zhao ZK, Zhu F. The role of human endogenous retroviral long terminal repeat sequences in human cancer (Review). Int J Mol Med 2013; 32:755-62. [PMID: 23900638 DOI: 10.3892/ijmm.2013.1460] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Accepted: 05/30/2013] [Indexed: 11/06/2022] Open
Abstract
Human endogenous retrovirus (HERV) and solitary long terminal repeats (LTRs) constitute 8% of the human genome. Although most HERV genes are partially deleted and not intact, HERV LTRs comprise features including promoters, enhancers, selective splicer sites and polyadenylation sites in order to regulate the expression of neighboring genes. Owing to the genetic instability of LTRs, their wide distributions along human chromosomes are not only non-random, but are also correlated with gene density. Considerable evidence indicates that HERV LTRs regulate the expression of their adjacent viral and cellular genes in placental development and tumorigenesis. However, the regulatory mechanism of HERV LTRs on the expression of its neighboring cancer-associated genes in human cancers remains to be elucidated. Insertional mutagenesis, recombination and polymorphism are three principal factors of LTR that contribute to its genetic instability. Moreover, genetic instability, hypomethylation, transactivation and the antisense transcript of LTRs enhance the activity of LTRs and regulate the expression of their adjacent genes in human cancers. Therefore, in the present review, we examined the mechanism of HERV LTRs in tumorigenesis in combination with the structure and function of LTRs.
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Affiliation(s)
- Hong-Lian Yu
- Department of Medical Microbiology, School of Medicine, Wuhan University, Wuhan, Hubei 430071, PR China
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23
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Kahyo T, Tao H, Shinmura K, Yamada H, Mori H, Funai K, Kurabe N, Suzuki M, Tanahashi M, Niwa H, Ogawa H, Tanioka F, Yin G, Morita M, Matsuo K, Kono S, Sugimura H. Identification and association study with lung cancer for novel insertion polymorphisms of human endogenous retrovirus. Carcinogenesis 2013; 34:2531-8. [PMID: 23872666 DOI: 10.1093/carcin/bgt253] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Sequences of human endogenous retroviruses (HERVs) are members of the long terminal repeat (LTR) retrotransposon family. Although the expression of HERV has long been a topic of investigation, HERV-insertion polymorphisms are not well known, and a genetic association between HERV-insertion polymorphisms and cancer has never been reported. To identify novel HERV loci in the genome from cancer tissues, we carried out the inverse PCR method targeting a conserved LTR region of HML-2, which is the most recently acquired HERV group. Novel two insertions, HML-2_sLTR(1p13.2) and HML-2_sLTR(19q12), were identified as insertionally polymorphic solo LTRs. Furthermore, a significant prevalence of HML-2_sLTR(1p13.2) homozygosity was detected in female never-smoking patients aged 60 years and over who had lung adenocarcinoma [versus the other genotyping; odds ratio (OR): 1.97; 95% confidence interval (CI): 1.01-3.81]. In another cohort consisting of female never-smoking patients with lung adenocarcinoma, a prevalence of HML-2_sLTR(1p13.2) homozygosity tended to be high in patients aged 60 years and over (versus the other genotyping; OR: 2.03; 95% CI: 0.96-4.29), whereas a low prevalence of HML-2_sLTR(1p13.2) homozygosity was detected in patients <60 years old (versus the other genotyping; OR: 0.31; 95% CI: 0.11-0.94). Our results suggest that HML-2_sLTR(1p13.2) is involved with the susceptibility to lung adenocarcinoma in female never-smokers in an age-dependent manner and that other HERV polymorphisms related to human diseases might remain to be identified in the human genome.
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24
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Zhao J, Rycaj K, Geng S, Li M, Plummer JB, Yin B, Liu H, Xu X, Zhang Y, Yan Y, Glynn SA, Dorsey TH, Ambs S, Johanning GL, Gu L, Wang-Johanning F. Expression of Human Endogenous Retrovirus Type K Envelope Protein is a Novel Candidate Prognostic Marker for Human Breast Cancer. Genes Cancer 2012; 2:914-22. [PMID: 22593804 DOI: 10.1177/1947601911431841] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Accepted: 11/04/2011] [Indexed: 01/14/2023] Open
Abstract
We previously observed that the HERV type K (HERV-K) envelope (env) protein was expressed in the majority of human breast tumors from a U.S. cohort of women from Texas. We also made the preliminary observation that the expression of HERV-K env transcripts was associated with markers of disease progression. In this follow-up study, env protein expression was evaluated immunohistochemically in an additional 195 paraffin-embedded breast tumors from a second U.S. patient cohort (Baltimore, Maryland) and in 110 tumors from Chinese patients. Moreover, we compared env transcript expression between fresh-frozen normal and cancerous breast tissues. We observed that while env mRNA and protein expression was undetectable in normal breast tissue and in a subset of uninvolved normal-appearing tissue adjacent to the tumor epithelium, it was overexpressed in most tumors. Furthermore, env expression was associated with breast cancer progression. In Baltimore cohort women, HERV-K tumor positivity was significantly associated with disease stage and lymph node metastasis. In Chinese women, HERV-K env positivity was significantly associated with tumor size, TNM stage, and lymph node metastases, which is consistent with the observations in the U.S. cohort. We also found that Chinese breast cancer patients with a high expression of HERV-K had a decreased overall survival compared with patients who had either a moderate or low HERV-K expression in their tumors (P = 0.049, χ(2) log rank test). In conclusion, the HERV-K env gene is expressed in the majority of breast cancers from U.S. or Chinese women but not in normal breast tissue. High expression of HERV-K env protein in breast cancer patients is associated with markers of disease progression and poor disease outcome, indicating that HERV-K env protein is a novel candidate prognostic marker for breast cancer.
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Affiliation(s)
- Jing Zhao
- Cancer Institute and Hospital of Tianjin Medical University, Tianjin, China
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25
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Jha AR, Pillai SK, York VA, Sharp ER, Storm EC, Wachter DJ, Martin JN, Deeks SG, Rosenberg MG, Nixon DF, Garrison KE. Cross-sectional dating of novel haplotypes of HERV-K 113 and HERV-K 115 indicate these proviruses originated in Africa before Homo sapiens. Mol Biol Evol 2009; 26:2617-26. [PMID: 19666991 PMCID: PMC2760466 DOI: 10.1093/molbev/msp180] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The human genome, human endogenous retroviruses (HERV), of which HERV-K113 and HERV-K115 are the only known full-length proviruses that are insertionally polymorphic. Although a handful of previously published papers have documented their prevalence in the global population; to date, there has been no report on their prevalence in the United States population. Here, we studied the geographic distribution of K113 and K115 among 156 HIV-1+ subjects from the United States, including African Americans, Hispanics, and Caucasians. In the individuals studied, we found higher insertion frequencies of K113 (21%) and K115 (35%) in African Americans compared with Caucasians (K113 9% and K115 6%) within the United States. We also report the presence of three single nucleotide polymorphism sites in the K113 5′ long terminal repeats (LTRs) and four in the K115 5′ LTR that together constituted four haplotypes for K113 and five haplotypes for K115. HERV insertion times can be estimated from the sequence differences between the 5′ and 3′ LTR of each insertion, but this dating method cannot be used with HERV-K115. We developed a method to estimate insertion times by applying coalescent inference to 5′ LTR sequences within our study population and validated this approach using an independent estimate derived from the genetic distance between K113 5′ and 3′ LTR sequences. Using our method, we estimated the insertion dates of K113 and K115 to be a minimum of 800,000 and 1.1 million years ago, respectively. Both these insertion dates predate the emergence of anatomically modern Homo sapiens.
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Affiliation(s)
- Aashish R Jha
- Division of Experimental Medicine, University of California San Francisco, CA, USA
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26
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Singh S, Kaye S, Gore ME, McClure MO, Bunker CB. The role of human endogenous retroviruses in melanoma. Br J Dermatol 2009; 161:1225-31. [PMID: 19785608 DOI: 10.1111/j.1365-2133.2009.09415.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sequencing of the human genome has established that our DNA harbours many endogenous retrovirus (ERV) sequences, remnants of ancestral exogenous retroviral infections fixed in the germline DNA. In recent years, human ERVs (HERVs) have been implicated in melanomagenesis. Retrovirus-like particles and the expression of HERV mRNA and proteins have been demonstrated in melanoma tissue. In addition, antibodies to HERV proteins have been observed in patients with melanoma. In vitro and mouse models have provided fascinating insights into the potential mechanisms of HERVs in melanomagenesis. This review considers the evidence associating HERVs with melanoma.
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Affiliation(s)
- S Singh
- Department of Dermatology, Chelsea and Westminster Hospital, Imperial College Faculty of Medicine, London, U.K.
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27
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Beimforde N, Hanke K, Ammar I, Kurth R, Bannert N. Molecular cloning and functional characterization of the human endogenous retrovirus K113. Virology 2008; 371:216-25. [PMID: 18076964 DOI: 10.1016/j.virol.2007.09.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 06/11/2007] [Accepted: 09/24/2007] [Indexed: 11/27/2022]
Abstract
The human endogenous retrovirus-K113 (HERV-K113) is the most complete HERV known to date. It contains open reading frames for all viral proteins. Depending on ethnicity, up to 30% of the human population carries the provirus on chromosome 19. To facilitate molecular and functional studies, we have cloned the HERV-K113 sequence into a small plasmid vector and characterized its functional properties. Here we show that based on a substantial LTR-promoter activity, full length messenger RNA and spliced env-, rec- and 1.5 kb (hel)-transcripts are produced. The envelope protein of HERV-K113 is synthesized as an 85 kDa precursor that is found partially processed. The accessory Rec protein is highly expressed and accumulates in the nucleus. Expression analysis revealed synthesis of the Gag precursor and the protease. However, the cloned HERV-K113 provirus is not replication competent. It carries inactivating mutations in the reverse transcriptase gene. These mutations can be reversed to reconstitute the active enzyme, but the reversion is not sufficient to reconstitute replication capacity of the virus.
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Affiliation(s)
- Nadine Beimforde
- Robert Koch-Institut, ZBS 4, Nordufer 20, 13353 Berlin, Germany.
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28
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Human endogenous retrovirus K (HML-2) elements in the plasma of people with lymphoma and breast cancer. J Virol 2008; 82:9329-36. [PMID: 18632860 DOI: 10.1128/jvi.00646-08] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Actively replicating endogenous retroviruses entered the human genome millions of years ago and became a stable part of the inherited genetic material. They subsequently acquired multiple mutations, leading to the assumption that these viruses no longer replicate. However, certain human tumor cell lines have been shown to release endogenous retroviral particles. Here we show that RNA from human endogenous retrovirus K (HERV-K) (HML-2), a relatively recent entrant into the human genome, can be found in very high titers in the plasma of patients with lymphomas and breast cancer as measured by either reverse transcriptase PCR or nucleic acid sequence-based amplification. Further, these titers drop dramatically with cancer treatment. We also demonstrate the presence of reverse transcriptase and viral RNA in plasma fractions that contain both immature and correctly processed HERV-K (HML-2) Gag and envelope proteins. Finally, using immunoelectron microscopy, we show the presence of HERV-K (HML-2) virus-like particles in the plasma of lymphoma patients. Taken together, these findings demonstrate that elements of the endogenous retrovirus HERV-K (HML-2) can be found in the blood of modern-day humans with certain cancers.
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Abstract
The capacity to integrate into the chromosomal DNA of germ-line cells has endowed retroviruses with the potential to be vertically transmitted from generation to generation and eventually become fixed in the genomes of the entire population. This has been independently accomplished by several ancient retroviruses that invaded the genomes of our early and more recent primate and hominoid ancestors. Some of the inherited elements then proliferated in the genome, resulting in a number of lineages with complex phylogenetic patterns. Although the vast majority of chromosomally integrated retroelements have suffered inactivating mutations and deletions, a significant impact on various aspects of human biology has been recently revealed and evidence for the present activity of at least one human endogenous retrovirus family continues to accumulate.
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Moyes DL, Goris A, Ban M, Compston A, Griffiths DJ, Sawcer S, Venables PJ. HERV-K113 is not associated with multiple sclerosis in a large family-based study. AIDS Res Hum Retroviruses 2008; 24:363-5. [PMID: 18327982 DOI: 10.1089/aid.2007.0196] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Numerous studies have invoked a role for retroviruses in multiple sclerosis (MS). Most have identified human endogenous retroviruses (HERVs) as possible etiological agents. The majority of HERVs originate from ancestral infection and then become progressively disabled by mutations over millions of years of primate evolution. Their presence in 100% of healthy humans, together with the paucity of functional retroviral genes, argues strongly against a causal role in disease. Recently, a new class of insertionally polymorphic HERVs has been described that is present in only a proportion of the population. One of them, HERV-K113, is notable for open reading frames for all of its genes and is found in 0-28% of humans with widespread geographic and racial variation. Thus HERV-K113 is a credible candidate for causing disease in a manner comparable to infectious retroviruses. Genomic DNA samples from 951 patients with MS were tested for the presence of the HERV-K113 allele by PCR, with their unaffected parents (n = 1902) acting as controls. HERV-K113 provirus was found in 70 out of 951 (7.36%) patients with MS and was not significantly increased compared to the combined parent group (6.52%). The results do not support an association between this endogenous retrovirus and MS. This study also emphasizes the need for large cohorts with controls for race and geographic location when examining possible links between polymorphic HERVs and disease.
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Affiliation(s)
- David L. Moyes
- The Kennedy Institute of Rheumatology, Imperial College, London, London W6 8LH, England
| | - An Goris
- University of Cambridge Department of Clinical Neurosciences, Addenbrooke's Hospital, Cambridge CB2 2QQ, England
| | - Maria Ban
- University of Cambridge Department of Clinical Neurosciences, Addenbrooke's Hospital, Cambridge CB2 2QQ, England
| | - Alistair Compston
- University of Cambridge Department of Clinical Neurosciences, Addenbrooke's Hospital, Cambridge CB2 2QQ, England
| | - David J. Griffiths
- Moredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, England
| | - Stephen Sawcer
- University of Cambridge Department of Clinical Neurosciences, Addenbrooke's Hospital, Cambridge CB2 2QQ, England
| | - Patrick J. Venables
- The Kennedy Institute of Rheumatology, Imperial College, London, London W6 8LH, England
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Voisset C, Weiss RA, Griffiths DJ. Human RNA "rumor" viruses: the search for novel human retroviruses in chronic disease. Microbiol Mol Biol Rev 2008; 72:157-96, table of contents. [PMID: 18322038 PMCID: PMC2268285 DOI: 10.1128/mmbr.00033-07] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Retroviruses are an important group of pathogens that cause a variety of diseases in humans and animals. Four human retroviruses are currently known, including human immunodeficiency virus type 1, which causes AIDS, and human T-lymphotropic virus type 1, which causes cancer and inflammatory disease. For many years, there have been sporadic reports of additional human retroviral infections, particularly in cancer and other chronic diseases. Unfortunately, many of these putative viruses remain unproven and controversial, and some retrovirologists have dismissed them as merely "human rumor viruses." Work in this field was last reviewed in depth in 1984, and since then, the molecular techniques available for identifying and characterizing retroviruses have improved enormously in sensitivity. The advent of PCR in particular has dramatically enhanced our ability to detect novel viral sequences in human tissues. However, DNA amplification techniques have also increased the potential for false-positive detection due to contamination. In addition, the presence of many families of human endogenous retroviruses (HERVs) within our DNA can obstruct attempts to identify and validate novel human retroviruses. Here, we aim to bring together the data on "novel" retroviral infections in humans by critically examining the evidence for those putative viruses that have been linked with disease and the likelihood that they represent genuine human infections. We provide a background to the field and a discussion of potential confounding factors along with some technical guidelines. In addition, some of the difficulties associated with obtaining formal proof of causation for common or ubiquitous agents such as HERVs are discussed.
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Affiliation(s)
- Cécile Voisset
- CNRS-UMR8161, Institut de Biologie de Lille et Institut Pasteur de Lille, Lille, France
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32
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Variable transcriptional activity of endogenous retroviruses in human breast cancer. J Virol 2007; 82:1808-18. [PMID: 18077721 DOI: 10.1128/jvi.02115-07] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Human endogenous retroviruses (HERVs) account for up to 9% of the human genome and include more than 800 elements related to betaretroviruses. While mouse mammary tumor virus (MMTV) is the accepted etiological agent of mammary tumors in mice, the role of retroviral elements in human breast cancer remains elusive. Here, we performed a comprehensive microarray-based analysis of overall retroviral transcriptional activities in 46 mammary gland tissue specimens representing pairs of nonmalignant and tumor samples from 23 patients. An analysis of nonmalignant tissue samples revealed a distinct, mammary gland-specific HERV expression profile that consists of 18 constitutively active HERV taxa. For corresponding tumor samples, a general trend toward lower levels of HERV transcription was observed, suggesting common regulatory mechanisms. In various subsets of patients, however, increased transcript levels of single class I HERV families (HERV-T, HERV-E, and HERV-F) and several class II families, including HML-6, were detected. An analysis of transcribed HML-6 sequences revealed either the activation of some or the increased activity of several proviral loci. No evidence for MMTV or human MMTV-like virus transcripts was found, indicating that transcriptionally active, MMTV analogous, exogenous viruses were not present in the breast cancer samples analyzed.
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Moyes D, Griffiths DJ, Venables PJ. Insertional polymorphisms: a new lease of life for endogenous retroviruses in human disease. Trends Genet 2007; 23:326-33. [PMID: 17524519 DOI: 10.1016/j.tig.2007.05.004] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Revised: 04/16/2007] [Accepted: 05/11/2007] [Indexed: 10/23/2022]
Abstract
Human endogenous retroviruses (HERVs) result from ancestral infection by infectious viruses over millions of years of primate evolution. Some are transcriptionally active, express proteins and therefore have the potential to cause disease. Here we review the controversial attempts to link them with cancer and autoimmunity. The main difficulty is that most HERVs investigated to date are present at the same locus in 100% of the population. However, a new class of insertionally polymorphic HERV-K family members, present in a minority of individuals, has recently been described. We propose that insertionally polymorphic HERVs could be novel genetic risk factors and hence provide a new lease of life for research into HERVs and disease.
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Affiliation(s)
- David Moyes
- The Kennedy Institute of Rheumatology, Imperial College London, London, UK
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Contreras-Galindo R, López P, Vélez R, Yamamura Y. HIV-1 infection increases the expression of human endogenous retroviruses type K (HERV-K) in vitro. AIDS Res Hum Retroviruses 2007; 23:116-22. [PMID: 17263641 DOI: 10.1089/aid.2006.0117] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Antibodies to HERV-K antigens have been linked to HIV-1 infection and expression of HERV-K proteins generates T-cell cytotoxic responses in many cancers. HERV-K RNA and protein abundance was measured in HIV-1-infected and control cells. In vitro exposure of HIV-1 laboratory-adapted and primary isolates on U87MG cells increased the expression of HERV-K RNA in a dose-dependent manner. HERV-K RNA and protein burdens were significantly increased in HIV-1-producing H9 cell lines compared to H9 cells. The expression of HERV-K was synergistically increased in HIV-1-infected PBMCs after stimulation with PMA/ionomycin. Furthermore, the expression of HERV-K in PBMCs, and particularly in CD4(+) T cells, was higher in HIV-1 patients compared to control subjects. The expression of HERV-K might be related to HIV-1 pathogenesis and AIDS-associated cancers.
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Otowa T, Tochigi M, Rogers M, Umekage T, Kato N, Sasaki T. Insertional polymorphism of endogenous retrovirus HERV-K115 in schizophrenia. Neurosci Lett 2006; 408:226-9. [PMID: 17000049 DOI: 10.1016/j.neulet.2006.09.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 08/20/2006] [Accepted: 09/03/2006] [Indexed: 11/24/2022]
Abstract
Retroviruses are implicated in the pathogenesis of schizophrenia. Human endogenous retrovirus type K115 (HERV-K115) is a full-length, potentially transcriptional retrovirus and is also polymorphic. We investigated the frequency of HERV-K115 in Japanese schizophrenia patients and healthy controls. No difference was found in the frequency between patients and controls (8.4% versus 9.4%, respectively). However, a marginal difference was observed in age at onset between the HERV-K positive and negative patients (p=0.057). The HERV-K115 insertion appeared to be more frequent in patients with younger onset than those with later onset. These results preliminarily suggest that HERV-K115 may not be associated with schizophrenia in general, but that it could play a partial role in early precipitation of the disease.
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Affiliation(s)
- Takeshi Otowa
- Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo, Bunkyo, Tokyo 113-8655, Japan
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Katzourakis A, Rambaut A, Pybus OG. The evolutionary dynamics of endogenous retroviruses. Trends Microbiol 2005; 13:463-8. [PMID: 16109487 DOI: 10.1016/j.tim.2005.08.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 07/22/2005] [Accepted: 08/08/2005] [Indexed: 11/23/2022]
Abstract
Endogenous retroviruses (ERVs) are vertically transmitted intragenomic elements derived from integrated retroviruses. ERVs can proliferate within the genome of their host until they either acquire inactivating mutations or are lost by recombinational deletion. We present a model that unifies current knowledge of ERV biology into a single evolutionary framework. The model predicts the possible long-term outcomes of retroviral germline infection and can account for the variable patterns of observed ERV genetic diversity. We hope the model will provide a useful framework for understanding ERV evolution, enabling the testing of evolutionary hypotheses and the estimation of parameters governing ERV proliferation.
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Affiliation(s)
- Aris Katzourakis
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
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