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Mercado NB, Real JN, Kaiserman J, Panagioti E, Cook CH, Lawler SE. Clinical implications of cytomegalovirus in glioblastoma progression and therapy. NPJ Precis Oncol 2024; 8:213. [PMID: 39343770 PMCID: PMC11439950 DOI: 10.1038/s41698-024-00709-4] [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: 05/07/2024] [Accepted: 09/16/2024] [Indexed: 10/01/2024] Open
Abstract
Glioblastoma (GBM) is one of the deadliest brain cancers with a median survival of only 15 months. This poor prognosis has prompted exploration of novel therapeutic targets for GBM patients. Human cytomegalovirus (HCMV) has been implicated in GBM; however, its impact remains poorly defined, and there is conflicting data over the presence of HCMV in tumors. Nonetheless, clinical trials targeting HCMV have shown promising initial data, and evidence suggests that HCMV may negatively impact GBM patient survival by multiple mechanisms including changes in GBM cell behavior and the tumor microenvironment (TME) that potentiate tumor progression as well as therapy-induced virus reactivation. Moreover, HCMV has many effects on host immunity that could impact tumor behavior by altering the TME, which are largely unexplored. The goal of this review is to describe these potential interactions between HCMV and GBM. Better understanding of these processes may allow the development of new therapeutic modalities to improve GBM patient outcomes.
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Affiliation(s)
- Noe B Mercado
- Department of Pathology and Laboratory Medicine, Legorreta Cancer Center, Brown University, Providence, RI, US
- The Warren Alpert Medical School, Brown University, Providence, RI, US
| | - Jacqueline N Real
- Department of Pathology and Laboratory Medicine, Legorreta Cancer Center, Brown University, Providence, RI, US
- The Warren Alpert Medical School, Brown University, Providence, RI, US
| | - Jacob Kaiserman
- Department of Pathology and Laboratory Medicine, Legorreta Cancer Center, Brown University, Providence, RI, US
- The Warren Alpert Medical School, Brown University, Providence, RI, US
| | - Eleni Panagioti
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, US
| | - Charles H Cook
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, US
| | - Sean E Lawler
- Department of Pathology and Laboratory Medicine, Legorreta Cancer Center, Brown University, Providence, RI, US.
- The Warren Alpert Medical School, Brown University, Providence, RI, US.
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Zeng J, Cao D, Yang S, Jaijyan DK, Liu X, Wu S, Cruz-Cosme R, Tang Q, Zhu H. Insights into the Transcriptome of Human Cytomegalovirus: A Comprehensive Review. Viruses 2023; 15:1703. [PMID: 37632045 PMCID: PMC10458407 DOI: 10.3390/v15081703] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
Human cytomegalovirus (HCMV) is a widespread pathogen that poses significant risks to immunocompromised individuals. Its genome spans over 230 kbp and potentially encodes over 200 open-reading frames. The HCMV transcriptome consists of various types of RNAs, including messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), with emerging insights into their biological functions. HCMV mRNAs are involved in crucial viral processes, such as viral replication, transcription, and translation regulation, as well as immune modulation and other effects on host cells. Additionally, four lncRNAs (RNA1.2, RNA2.7, RNA4.9, and RNA5.0) have been identified in HCMV, which play important roles in lytic replication like bypassing acute antiviral responses, promoting cell movement and viral spread, and maintaining HCMV latency. CircRNAs have gained attention for their important and diverse biological functions, including association with different diseases, acting as microRNA sponges, regulating parental gene expression, and serving as translation templates. Remarkably, HCMV encodes miRNAs which play critical roles in silencing human genes and other functions. This review gives an overview of human cytomegalovirus and current research on the HCMV transcriptome during lytic and latent infection.
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Affiliation(s)
- Janine Zeng
- Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, 225 Warren Street, Newark, NJ 070101, USA
| | - Di Cao
- Department of Pain Medicine, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen 518052, China
| | - Shaomin Yang
- Department of Pain Medicine, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen 518052, China
| | - Dabbu Kumar Jaijyan
- Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, 225 Warren Street, Newark, NJ 070101, USA
| | - Xiaolian Liu
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China
| | - Songbin Wu
- Department of Pain Medicine, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen 518052, China
| | - Ruth Cruz-Cosme
- Department of Microbiology, Howard University College of Medicine, 520 W Street NW, Washington, DC 20059, USA
| | - Qiyi Tang
- Department of Microbiology, Howard University College of Medicine, 520 W Street NW, Washington, DC 20059, USA
| | - Hua Zhu
- Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, 225 Warren Street, Newark, NJ 070101, USA
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Yu C, He S, Zhu W, Ru P, Ge X, Govindasamy K. Human cytomegalovirus in cancer: the mechanism of HCMV-induced carcinogenesis and its therapeutic potential. Front Cell Infect Microbiol 2023; 13:1202138. [PMID: 37424781 PMCID: PMC10327488 DOI: 10.3389/fcimb.2023.1202138] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 06/08/2023] [Indexed: 07/11/2023] Open
Abstract
Cancer is one of the leading causes of death worldwide. Human cytomegalovirus (HCMV), a well-studied herpesvirus, has been implicated in malignancies derived from breast, colorectal muscle, brain, and other cancers. Intricate host-virus interactions are responsible for the cascade of events that have the potential to result in the transformed phenotype of normal cells. The HCMV genome contains oncogenes that may initiate these types of cancers, and although the primary HCMV infection is usually asymptomatic, the virus remains in the body in a latent or persistent form. Viral reactivation causes severe health issues in immune-compromised individuals, including cancer patients, organ transplants, and AIDS patients. This review focuses on the immunologic mechanisms and molecular mechanisms of HCMV-induced carcinogenesis, methods of HCMV treatment, and other studies. Studies show that HCMV DNA and virus-specific antibodies are present in many types of cancers, implicating HCMV as an important player in cancer progression. Importantly, many clinical trials have been initiated to exploit HCMV as a therapeutic target for the treatment of cancer, particularly in immunotherapy strategies in the treatment of breast cancer and glioblastoma patients. Taken together, these findings support a link between HCMV infections and cellular growth that develops into cancer. More importantly, HCMV is the leading cause of birth defects in newborns, and infection with HCMV is responsible for abortions in pregnant women.
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Affiliation(s)
- Chuan Yu
- Animal Diseases and Public Health Engineering Research Center of Henan Province, Luoyang Polytechnic, Luoyang, Henan, China
| | - Suna He
- Department of Pharmaceutical Sciences, School of Basic Medical Sciences, Henan University of Science and Technology, Luoyang, Henan, China
| | - Wenwen Zhu
- Animal Diseases and Public Health Engineering Research Center of Henan Province, Luoyang Polytechnic, Luoyang, Henan, China
| | - Penghui Ru
- Animal Diseases and Public Health Engineering Research Center of Henan Province, Luoyang Polytechnic, Luoyang, Henan, China
| | - Xuemei Ge
- School of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing, Jiangsu, China
| | - Kavitha Govindasamy
- School of Arts and Science, Rutgers, the State University of New Jersey, Newark, NJ, United States
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Daei Sorkhabi A, Sarkesh A, Saeedi H, Marofi F, Ghaebi M, Silvestris N, Baradaran B, Brunetti O. The Basis and Advances in Clinical Application of Cytomegalovirus-Specific Cytotoxic T Cell Immunotherapy for Glioblastoma Multiforme. Front Oncol 2022; 12:818447. [PMID: 35515137 PMCID: PMC9062077 DOI: 10.3389/fonc.2022.818447] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 03/24/2022] [Indexed: 01/28/2023] Open
Abstract
A high percentage of malignant gliomas are infected by human cytomegalovirus (HCMV), and the endogenous expression of HCMV genes and their products are found in these tumors. HCMV antigen expression and its implications in gliomagenesis have emerged as a promising target for adoptive cellular immunotherapy (ACT) strategies in glioblastoma multiforme (GB) patients. Since antigen-specific T cells in the tumor microenvironments lack efficient anti-tumor immune response due to the immunosuppressive nature of glioblastoma, CMV-specific ACT relies on in vitro expansion of CMV-specific CD8+ T cells employing immunodominant HCMV antigens. Given the fact that several hurdles remain to be conquered, recent clinical trials have outlined the feasibility of CMV-specific ACT prior to tumor recurrence with minimal adverse effects and a substantial improvement in median overall survival and progression-free survival. This review discusses the role of HCMV in gliomagenesis, disease prognosis, and recent breakthroughs in harnessing HCMV-induced immunogenicity in the GB tumor microenvironment to develop effective CMV-specific ACT.
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Affiliation(s)
- Amin Daei Sorkhabi
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Aila Sarkesh
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Hossein Saeedi
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Faroogh Marofi
- Department of Hematology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mahnaz Ghaebi
- Cancer Gene Therapy Research Center (CGRC), Zanjan University of Medical Sciences, Zanjan, Iran
| | - Nicola Silvestris
- Medical Oncology Unit, Department of Human Pathology "G. Barresi", University of Messina, Messina, Italy
| | - Behzad Baradaran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Oronzo Brunetti
- Medical Oncology Unit-Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Tumori “Giovanni Paolo II” of Bari, Bari, Italy
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High accumulation of Mx2 renders limited multiplication of oncolytic herpes simplex virus-1 in human tumor cells. Sci Rep 2021; 11:21227. [PMID: 34707174 PMCID: PMC8551283 DOI: 10.1038/s41598-021-00691-y] [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: 08/23/2021] [Accepted: 10/14/2021] [Indexed: 11/08/2022] Open
Abstract
Increasing studies demonstrated that oncolytic activities of oHSV-1 are limited to the capacity of virus replicating in tumors. In order to potentiate the oHSV-1 oncolytic activity and expand the application of oHSV-1 treatment in multiple types of tumors, it is critical to explore the potential factors or mechanisms mediating tumor resistance to oHSV-1 infection. Here we evaluated the levels of oHSV-1 multiplication in various tumor cell lines and showed that glioblastoma cell line A172 had the lowest virus yields but intrinsically accumulated the highest levels of Mx2 protein. Subsequently we demonstrated that genetic depletion of Mx2 specifically enhanced oHSV-1 productive replication in A172 cells through promoting the nuclear translocation of uncoated viral genomic DNA and down-regulating innate antiviral response. In the further investigation, we found that Mx2 knockdown could alter the intrinsic mRNA accumulation of diverse sets innate immune genes in A172 cells, in particular DHX36 and MyD88. Mx2 depletion led to a decrease in mRNA levels of MyD88 and DHX36 in A172 cells and MyD88/DHX36 knockdown increased virus yield in A172 cells and decreased the production of IFNα, activation of IRF3 activity and NF-κB signaling in A172 cells. This shed new lights on understanding the roles of some intrinsic antiviral genes in oHSV-1 resistance, facilitating to offer potential targets to improve oHSV-1 oncolytic efficacy and develop candidates of biomarkers to predict the efficiency of oHSV-1 multiplication in tumors.
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Zhu W, Liu S. The role of human cytomegalovirus in atherosclerosis: a systematic review. Acta Biochim Biophys Sin (Shanghai) 2020; 52:339-353. [PMID: 32253424 DOI: 10.1093/abbs/gmaa005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/05/2019] [Accepted: 01/20/2020] [Indexed: 12/11/2022] Open
Abstract
Atherosclerosis is a progressive vascular disease with increasing morbidity and mortality year by year in modern society. Human cytomegalovirus (HCMV) infection is closely associated with the development of atherosclerosis. HCMV infection may accelerate graft atherosclerosis and the development of transplant vasculopathy in organ transplantation. However, our current understanding of HCMV-associated atherosclerosis remains limited and is mainly based on clinical observations. The underlying mechanism of the involvement of HCMV infection in atherogenesis remains unclear. Here, we summarized current knowledge regarding the multiple influences of HCMV on a diverse range of infected cells, including vascular endothelial cells, vascular smooth muscle cells, monocytes, macrophages, and T cells. In addition, we described potential HCMV-induced molecular mechanisms, such as oxidative stress, endoplasmic reticulum stress, autophagy, lipid metabolism, and miRNA regulation, which are involved in the development of HCMV-associated atherogenesis. Gaining an improved understanding of these mechanisms will facilitate the development of novel and effective therapeutic strategies for the treatment of HCMV-related cardiovascular disease.
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Affiliation(s)
- Wenbo Zhu
- Clinical Research Institute, First Affiliated Hospital, University of South China, Hengyang 421001, China
| | - Shuangquan Liu
- Clinical Laboratory, First Affiliated Hospital, University of South China, Hengyang 421001, China
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Vardi N, Chaturvedi S, Weinberger LS. Feedback-mediated signal conversion promotes viral fitness. Proc Natl Acad Sci U S A 2018; 115:E8803-E8810. [PMID: 30150412 PMCID: PMC6140503 DOI: 10.1073/pnas.1802905115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A fundamental signal-processing problem is how biological systems maintain phenotypic states (i.e., canalization) long after degradation of initial catalyst signals. For example, to efficiently replicate, herpesviruses (e.g., human cytomegalovirus, HCMV) rapidly counteract cell-mediated silencing using transactivators packaged in the tegument of the infecting virion particle. However, the activity of these tegument transactivators is inherently transient-they undergo immediate proteolysis but delayed synthesis-and how transient activation sustains lytic viral gene expression despite cell-mediated silencing is unclear. By constructing a two-color, conditional-feedback HCMV mutant, we find that positive feedback in HCMV's immediate-early 1 (IE1) protein is of sufficient strength to sustain HCMV lytic expression. Single-cell time-lapse imaging and mathematical modeling show that IE1 positive feedback converts transient transactivation signals from tegument pp71 proteins into sustained lytic expression, which is obligate for efficient viral replication, whereas attenuating feedback decreases fitness by promoting a reversible silenced state. Together, these results identify a regulatory mechanism enabling herpesviruses to sustain expression despite transient activation signals-akin to early electronic transistors-and expose a potential target for therapeutic intervention.
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Affiliation(s)
- Noam Vardi
- Gladstone-University of California, San Francisco (UCSF) Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158
| | - Sonali Chaturvedi
- Gladstone-University of California, San Francisco (UCSF) Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158
| | - Leor S Weinberger
- Gladstone-University of California, San Francisco (UCSF) Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158;
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158
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8
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The Human Cytomegalovirus, from Oncomodulation to Oncogenesis. Viruses 2018; 10:v10080408. [PMID: 30081496 PMCID: PMC6115842 DOI: 10.3390/v10080408] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 07/30/2018] [Accepted: 08/01/2018] [Indexed: 12/13/2022] Open
Abstract
Besides its well-described impact in immunosuppressed patients, the role of human cytomegalovirus (HCMV) in the pathogenesis of cancer has been more recently investigated. In cancer, HCMV could favor the progression and the spread of the tumor, a paradigm named oncomodulation. Although oncomodulation could account for part of the protumoral effect of HCMV, it might not explain the whole impact of HCMV infection on the tumor and the tumoral microenvironment. On the contrary cases have been reported where HCMV infection slows down the progression and the spread of the tumor. In addition, HCMV proteins have oncogenic properties per se, HCMV activates pro-oncogenic pathways in infected cells, and recently the direct transformation of cells following HCMV infection has been described, which gave rise to tumors when injected in mice. Thus, beyond the oncomodulation model, this review will assess the direct transforming role of HMCV-infected cells and the potential classification of HCMV as an oncovirus.
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Multiplex CRISPR/Cas9 system impairs HCMV replication by excising an essential viral gene. PLoS One 2018; 13:e0192602. [PMID: 29447206 PMCID: PMC5813945 DOI: 10.1371/journal.pone.0192602] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/28/2018] [Indexed: 01/20/2023] Open
Abstract
Anti-HCMV treatments used in immunosuppressed patients reduce viral replication, but resistant viral strains can emerge. Moreover, these drugs do not target latently infected cells. We designed two anti-viral CRISPR/Cas9 strategies to target the UL122/123 gene, a key regulator of lytic replication and reactivation from latency. The singleplex strategy contains one gRNA to target the start codon. The multiplex strategy contains three gRNAs to excise the complete UL122/123 gene. Primary fibroblasts and U-251 MG cells were transduced with lentiviral vectors encoding Cas9 and one or three gRNAs. Both strategies induced mutations in the target gene and a concomitant reduction of immediate early (IE) protein expression in primary fibroblasts. Further detailed analysis in U-251 MG cells showed that the singleplex strategy induced 50% of indels in the viral genome, leading to a reduction in IE protein expression. The multiplex strategy excised the IE gene in 90% of all viral genomes and thus led to the inhibition of IE protein expression. Consequently, viral genome replication and late protein expression were reduced by 90%. Finally, the production of new viral particles was nearly abrogated. In conclusion, the multiplex anti-UL122/123 CRISPR/Cas9 system can target the viral genome efficiently enough to significantly prevent viral replication.
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Du Y, Zhang G, Liu Z. Human cytomegalovirus infection and coronary heart disease: a systematic review. Virol J 2018; 15:31. [PMID: 29409508 PMCID: PMC5801777 DOI: 10.1186/s12985-018-0937-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 01/18/2018] [Indexed: 12/15/2022] Open
Abstract
Background Human cytomegalovirus (HCMV) infection is closely associated with coronary heart disease. Main body of the abstract In 1987, Adam et al. were the first to report an association between HCMV infection and atherosclerosis (AS), and later, many serum epidemiology and molecular biology studies showed that HCMV-infected endothelial cells play an important role in the development of AS. As patients with HCMV are generally susceptible to coronary heart disease, and with the increasing elderly population, a review of recent studies focusing on the relationships of HCMV infection and coronary heart disease is timely and necessary. Short conclusion The role of HCMV infection in the development of AS needs further study, since many remaining issues need to be explored and resolved. For example, whether HCMV promotes the development of coronary AS, and what the independent factors that lead to coronary artery AS by viral infection are. A comprehensive understanding of HCMV infection is needed in order to develop better strategies for preventing AS.
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Affiliation(s)
- Yu Du
- Department of Microbiology, Weifang Medical University, Weifang, 261053, China
| | - Guangxue Zhang
- Department of Clinical Laboratory, Shandong Qingzhou Rongjun Hospital, Qingzhou, 262500, China
| | - Zhijun Liu
- Department of Microbiology, Weifang Medical University, Weifang, 261053, China.
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11
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Teo WH, Chen HP, Huang JC, Chan YJ. Human cytomegalovirus infection enhances cell proliferation, migration and upregulation of EMT markers in colorectal cancer-derived stem cell-like cells. Int J Oncol 2017; 51:1415-1426. [PMID: 29048611 PMCID: PMC5642395 DOI: 10.3892/ijo.2017.4135] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/04/2017] [Indexed: 02/06/2023] Open
Abstract
Increasing evidence suggests a link between persistent human cytomegalovirus (HCMV) infection and cancer. Although the role of HCMV in cancer is still elusive, recent studies revealed the presence of HCMV nucleic acids and proteins in different cancer types such as glioblastoma, colorectal, breast, and prostate cancers, and neuroblastoma. Although HCMV may not be directly associated with the neoplastic transformation, the presence of HCMV DNA in the tumorous tissue has been associated with altered clinical outcomes in cancer patients. However, the mechanisms involved in the association between colorectal cancer (CRC) and HCMV are unclear. In this study, we investigated the influence of HCMV infection on CRC or their derived cells. Proliferation and migration assays revealed a high infection efficiency in CRC-derived HT29 and SW480 'stem-like' cells. After 24, 48 and 72 h of HCMV infection, both HT29 and SW480 parental and stem-like cells showed a significant increase in cell proliferation and viability (p<0.0001). Moreover, HCMV infection promoted cell migration. These results demonstrate a significant phenotypic alteration in the CRC cell line upon HCMV infection. Using epithelial to mesenchymal transition (EMT) assays, we demonstrated that the EMT markers and driver genes were upregulated during the virus infection. The WNT signaling pathway, which is associated with the proliferation and migration of CRC cells, was upregulated (6-fold) in HCMV-infected cells as compared to the non-infected cells at day 7 from infection.
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Affiliation(s)
- Wan Huai Teo
- Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei, Taiwan, R.O.C
| | - Hsin-Pai Chen
- Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, R.O.C
| | - Jason C Huang
- Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei, Taiwan, R.O.C
| | - Yu-Jiun Chan
- Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, R.O.C
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Valle Oseguera CA, Spencer JV. Human cytomegalovirus interleukin-10 enhances matrigel invasion of MDA-MB-231 breast cancer cells. Cancer Cell Int 2017; 17:24. [PMID: 28228690 PMCID: PMC5307693 DOI: 10.1186/s12935-017-0399-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 02/08/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND While some risk factors for breast cancer are well-known, the influence of other factors, particularly virus infection, remains unclear. Human cytomegalovirus (HCMV) is widespread in the general population, and both molecular and epidemiological evidence has indicated links between HCMV and breast cancer. The HCMV protein cmvIL-10 is a potent suppressor of immune function that has also been shown to promote proliferation and migration of breast cancer cells. In this study, the impact of cmvIL-10 on tumor cell invasion through a simulated basement membrane was investigated. RESULTS MDA-MB-231 breast cancer cells exhibited invasion through a matrigel layer that was significantly enhanced in the presence of either purified cmvIL-10 or supernatants from HCMV-infected cells containing secreted cmvIL-10. Transcriptional profiling revealed that cmvIL-10 altered expression of several genes implicated in metastasis. Exposure to cmvIL-10 resulted in higher MMP-3 mRNA levels, greater protein expression, and increased enzymatic activity. Treatment with cmvIL-10 also increased expression of both urokinase plasminogen receptor (uPAR) and plasminogen activator inhibitor-1 (PAI-1), which can stimulate MMP-3 activity and have previously been identified as poor prognostic markers in breast cancer patients. Finally, MDA-MB-231 cells treated with cmvIL-10 showed significant downregulation of metastasis suppressor 1 (MTSS1), a scaffolding protein that regulates cytoskeletal rearrangements and is frequently lost in metastatic tumors. CONCLUSIONS HCMV, and in particular the secreted viral cytokine, cmvIL-10, can induce cellular changes that facilitate cell migration and invasion. These findings indicate that HCMV may be associated with promoting the malignant spread of breast cancer cells and suggest that antiviral treatment may be a useful complement to chemotherapy in some patients.
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Affiliation(s)
- Cendy A Valle Oseguera
- Department of Biology, University of San Francisco, 2130 Fulton Street, San Francisco, CA 94117 USA
| | - Juliet V Spencer
- Department of Biology, University of San Francisco, 2130 Fulton Street, San Francisco, CA 94117 USA
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13
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Kuan MI, O'Dowd JM, Chughtai K, Hayman I, Brown CJ, Fortunato EA. Human Cytomegalovirus nuclear egress and secondary envelopment are negatively affected in the absence of cellular p53. Virology 2016; 497:279-293. [PMID: 27498410 DOI: 10.1016/j.virol.2016.07.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/10/2016] [Accepted: 07/19/2016] [Indexed: 01/10/2023]
Abstract
Human Cytomegalovirus (HCMV) infection is compromised in cells lacking p53, a transcription factor that mediates cellular stress responses. In this study we have investigated compromised functional virion production in cells with p53 knocked out (p53KOs). Infectious center assays found most p53KOs released functional virions. Analysis of electron micrographs revealed modestly decreased capsid production in infected p53KOs compared to wt. Substantially fewer p53KOs displayed HCMV-induced infoldings of the inner nuclear membrane (IINMs). In p53KOs, fewer capsids were found in IINMs and in the cytoplasm. The deficit in virus-induced membrane remodeling within the nucleus of p53KOs was mirrored in the cytoplasm, with a disproportionately smaller number of capsids re-enveloped. Reintroduction of p53 substantially recovered these deficits. Overall, the absence of p53 contributed to inhibition of the formation and function of IINMs and re-envelopment of the reduced number of capsids able to reach the cytoplasm.
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Affiliation(s)
- Man I Kuan
- Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, Moscow, ID, USA
| | - John M O'Dowd
- Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, Moscow, ID, USA
| | - Kamila Chughtai
- Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, Moscow, ID, USA
| | - Ian Hayman
- Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, Moscow, ID, USA
| | - Celeste J Brown
- Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, Moscow, ID, USA
| | - Elizabeth A Fortunato
- Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, Moscow, ID, USA.
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14
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Soroceanu L, Matlaf L, Khan S, Akhavan A, Singer E, Bezrookove V, Decker S, Ghanny S, Hadaczek P, Bengtsson H, Ohlfest J, Luciani-Torres MG, Harkins L, Perry A, Guo H, Soteropoulos P, Cobbs CS. Cytomegalovirus Immediate-Early Proteins Promote Stemness Properties in Glioblastoma. Cancer Res 2015; 75:3065-76. [PMID: 26239477 DOI: 10.1158/0008-5472.can-14-3307] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glioblastoma (GBM) is the most common and aggressive human brain tumor. Human cytomegalovirus (HCMV) immediate-early (IE) proteins that are endogenously expressed in GBM cells are strong viral transactivators with oncogenic properties. Here, we show how HCMV IEs are preferentially expressed in glioma stem-like cells (GSC), where they colocalize with the other GBM stemness markers, CD133, Nestin, and Sox2. In patient-derived GSCs that are endogenously infected with HCMV, attenuating IE expression by an RNAi-based strategy was sufficient to inhibit tumorsphere formation, Sox2 expression, cell-cycle progression, and cell survival. Conversely, HCMV infection of HMCV-negative GSCs elicited robust self-renewal and proliferation of cells that could be partially reversed by IE attenuation. In HCMV-positive GSCs, IE attenuation induced a molecular program characterized by enhanced expression of mesenchymal markers and proinflammatory cytokines, resembling the therapeutically resistant GBM phenotype. Mechanistically, HCMV/IE regulation of Sox2 occurred via inhibition of miR-145, a negative regulator of Sox2 protein expression. In a spontaneous mouse model of glioma, ectopic expression of the IE1 gene (UL123) specifically increased Sox2 and Nestin levels in the IE1-positive tumors, upregulating stemness and proliferation markers in vivo. Similarly, human GSCs infected with the HCMV strain Towne but not the IE1-deficient strain CR208 showed enhanced growth as tumorspheres and intracranial tumor xenografts, compared with mock-infected human GSCs. Overall, our findings offer new mechanistic insights into how HCMV/IE control stemness properties in GBM cells.
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Affiliation(s)
- Liliana Soroceanu
- Department of Neurosciences, California Pacific Medical Center Research Institute, San Francisco, California.
| | - Lisa Matlaf
- Department of Neurosciences, California Pacific Medical Center Research Institute, San Francisco, California
| | - Sabeena Khan
- Department of Neurosciences, California Pacific Medical Center Research Institute, San Francisco, California
| | - Armin Akhavan
- Department of Neurosciences, California Pacific Medical Center Research Institute, San Francisco, California
| | - Eric Singer
- Department of Neurosciences, California Pacific Medical Center Research Institute, San Francisco, California
| | - Vladimir Bezrookove
- Department of Neurosciences, California Pacific Medical Center Research Institute, San Francisco, California
| | - Stacy Decker
- Department of Pediatrics and Neurosurgery, University of Minnesota Masonic Cancer Center, Minneapolis, Minnesota
| | - Saleena Ghanny
- Center for Applied Genomics, Institute of Genomic Medicine, University of Medicine and Dentistry of New Jersey, Newark, New Jersey
| | - Piotr Hadaczek
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Henrik Bengtsson
- Department of Epidemiology and Biostatistics, University of California, San Francisco, California
| | - John Ohlfest
- Department of Pediatrics and Neurosurgery, University of Minnesota Masonic Cancer Center, Minneapolis, Minnesota
| | - Maria-Gloria Luciani-Torres
- Department of Neurosciences, California Pacific Medical Center Research Institute, San Francisco, California
| | - Lualhati Harkins
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Arie Perry
- Department of Pathology, University of California, San Francisco, California
| | - Hong Guo
- Center for Applied Genomics, Institute of Genomic Medicine, University of Medicine and Dentistry of New Jersey, Newark, New Jersey
| | - Patricia Soteropoulos
- Center for Applied Genomics, Institute of Genomic Medicine, University of Medicine and Dentistry of New Jersey, Newark, New Jersey
| | - Charles S Cobbs
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California. Ben and Catherine Ivy Center for Advanced Brain Tumor Treatment, Seattle, Washington.
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15
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Spector DH. Human cytomegalovirus riding the cell cycle. Med Microbiol Immunol 2015; 204:409-19. [PMID: 25776080 DOI: 10.1007/s00430-015-0396-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 02/19/2015] [Indexed: 12/25/2022]
Abstract
Human cytomegalovirus (HCMV) infection modulates the host cell cycle to create an environment that is optimal for viral gene expression, DNA replication, and production of infectious virus. The virus mostly infects quiescent cells and thus must push the cell into G1 phase of the cell cycle to co-opt the cellular mechanisms that could be used for DNA synthesis. However, at the same time, cellular functions must be subverted such that synthesis of viral DNA is favored over that of the host. The molecular mechanisms by which this is accomplished include altered RNA transcription, changes in the levels and activity of cyclin-dependent kinases, and other proteins involved in cell cycle control, posttranslational modifications of proteins, modulation of protein stability through targeted effects on the ubiquitin-proteasome degradation pathway, and movement of proteins to different cellular locations. When the cell is in the optimal G0/G1 phase, multiple signaling pathways are altered to allow rapid induction of viral gene expression once negative factors have been eliminated. For the most part, the cell cycle will stop prior to initiation of host cell DNA synthesis (S phase), although many cell cycle proteins characteristic of the S/G2/M phase accumulate. The environment of a cell progressing through the cell cycle and dividing is not favorable for viral replication, and HCMV has evolved ways to sense whether cells are in S/G2 phase, and if so, to prevent initiation of viral gene expression until the cells cycle back to G1. A major target of HCMV is the anaphase-promoting complex E3 ubiquitin ligase, which is responsible for the ubiquitination and subsequent degradation of cyclins A and B and other cell cycle proteins at specific phases in the cell cycle. This review will discuss the effects of HCMV infection on cell cycle regulatory pathways, with the focus on selected viral proteins that are responsible for these effects.
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Affiliation(s)
- Deborah H Spector
- Department of Cellular and Molecular Medicine, The Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, 92093-0712, USA,
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16
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Abstract
In 1908, Oluf Bang and Vilhelm Ellerman laid the foundation for theory of oncoviruses by demonstrating that the avian erythroblastosis (a form of chicken leukaemia) could be transmitted by cell-free extracts. Since then, it has been shown very convincingly that viruses can directly cause several human cancers by various mechanisms. Epidemiological data imply that viruses are the second most important risk factor for cancer development in humans, exceeded only by tobacco consumption. Although the ability of certain viruses (hepatitis B and C, human papillomavirus, etc) to cause cancer has been time tested and proven scientifically, there are several other potential viral candidates whose role in oncogenesis is more controversial. One such controversial scenario involves the role of cytomegalovirus (CMV) in malignant gliomas, the most common form of primary brain tumour. CMV first attracted attention about a decade ago when CMV gene products were found in glioma tissue but not in normal brain. Since this initial observation, several different groups have shown an oncomodulatory effect of CMV; however, direct association between CMV infection and incidence of glioma is lacking. In this review, we will evaluate the evidence, both preclinical and clinical, regarding the possible role of CMV in gliomagenesis and maintenance. We will also critically evaluate the rationale for using antiviral drugs in the treatment of patients with glioma.
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Affiliation(s)
- Mahua Dey
- The Brain Tumor Center, The University of Chicago, Chicago, Illinois, USA
| | - Atique U Ahmed
- The Brain Tumor Center, The University of Chicago, Chicago, Illinois, USA
| | - Maciej S Lesniak
- The Brain Tumor Center, The University of Chicago, Chicago, Illinois, USA
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17
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Liao XH, Dong X, Wu C, Wang T, Liu F, Zhou J, Zhang TC. Human cytomegalovirus immediate early protein 2 enhances myocardin-mediated survival of rat aortic smooth muscle cells. Virus Res 2014; 192:85-91. [PMID: 25157858 DOI: 10.1016/j.virusres.2014.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/15/2014] [Accepted: 08/17/2014] [Indexed: 11/24/2022]
Abstract
Human cytomegalovirus (HCMV) may increase the incidence of restenosis and predispose to atherosclerosis. The lesions of restenosis and atherosclerosis often contain smooth muscle cells (SMCs) with high rates of proliferation and apoptosis. One of the immediate early (IE) gene products of HCMV-IE2 affects transcriptional activities of some cellular factors in SMCs, including myocardin. In this study, we studied the effects of IE2 and myocardin on PI3K pathway inducer wortmannin induced apoptosis in rat aortic SMCs. We show that the transcriptional activity of myocardin on Mcl-1 promoter is enhanced by co-expression of HCMV IE2 in rat aortic SMCs; and the expressions of mRNA and protein of antiapoptotic genes-Mcl-1 and Bcl-2 are upregulated by IE2 alone and co-transfection of myocardin and IE2, but decreased by myocardin-specific shRNA in rat aortic SMCs. We further demonstrate that co-expression of myocardin and HCMV IE2 declines apoptotic cell numbers and caspase-3 activities induced by serum starvation plus wortmannin in rat aortic SMCs. The results suggest that HCMV IE2 enhances myocardin-mediated survival of rat aortic SMCs under serum deprivation and PI3-kinase inhibition, partly via activation of Mcl-1's antiapoptosis effect. Our study connects HCMV IE2 to myocardin-induced transcriptional program for rat aortic SMCs survival and proliferation, involving in HCMV related restenosis and atherosclerosis.
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Affiliation(s)
- Xing-Hua Liao
- Institute of Biological Medicine, and Medical School, Wuhan University of Science and Technology, Wuhan, Hubei 430065, China
| | - Xiumei Dong
- Institute of Biological Medicine, and Medical School, Wuhan University of Science and Technology, Wuhan, Hubei 430065, China
| | - Chenyu Wu
- Institute of Biological Medicine, and Medical School, Wuhan University of Science and Technology, Wuhan, Hubei 430065, China
| | - Tao Wang
- Institute of Biological Medicine, and Medical School, Wuhan University of Science and Technology, Wuhan, Hubei 430065, China
| | - Fenyong Liu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430071, China
| | - Jun Zhou
- Institute of Biological Medicine, and Medical School, Wuhan University of Science and Technology, Wuhan, Hubei 430065, China.
| | - Tong-Cun Zhang
- Institute of Biological Medicine, and Medical School, Wuhan University of Science and Technology, Wuhan, Hubei 430065, China; Key Laboratory of Industrial Microbiology, Ministry of Education and Tianjin City, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China.
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18
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Xiaofei E, Kowalik TF. The DNA damage response induced by infection with human cytomegalovirus and other viruses. Viruses 2014; 6:2155-85. [PMID: 24859341 PMCID: PMC4036536 DOI: 10.3390/v6052155] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 05/02/2014] [Accepted: 05/08/2014] [Indexed: 12/12/2022] Open
Abstract
Viruses use different strategies to overcome the host defense system. Recent studies have shown that viruses can induce DNA damage response (DDR). Many of these viruses use DDR signaling to benefit their replication, while other viruses block or inactivate DDR signaling. This review focuses on the effects of DDR and DNA repair on human cytomegalovirus (HCMV) replication. Here, we review the DDR induced by HCMV infection and its similarities and differences to DDR induced by other viruses. As DDR signaling pathways are critical for the replication of many viruses, blocking these pathways may represent novel therapeutic opportunities for the treatment of certain infectious diseases. Lastly, future perspectives in the field are discussed.
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Affiliation(s)
- E Xiaofei
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, 368 Plantation St, Worcester, MA 01605, USA.
| | - Timothy F Kowalik
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, 368 Plantation St, Worcester, MA 01605, USA.
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19
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Scherer M, Stamminger T. The human cytomegalovirus IE1 protein: past and present developments. Future Virol 2014. [DOI: 10.2217/fvl.14.20] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
ABSTRACT: Human cytomegalovirus (HCMV), a member of the β-herpesvirus subfamily, is an important pathogen that infects the majority of the human population. The evolutionary success of HCMV largely depends on its ability to evade host defense systems and establish a lifelong persistence after primary infection. In fact, HCMV has dedicated a considerable part of its gene products to manipulate or disable immune effector processes. This review focuses on the major immediate–early protein IE1 – a multifunctional key regulator that has the capacity to counteract the first host defense activities. We summarize the known structural and mechanistic features by which IE1 modulates innate immune mechanisms as well as other cellular processes, and discuss how the individual functions of IE1 contribute to the success of a lytic HCMV infection.
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Affiliation(s)
- Myriam Scherer
- Institute for Clinical & Molecular Virology, University of Erlangen-Nuremberg, Schlossgarten 4, 91054 Erlangen, Germany
| | - Thomas Stamminger
- Institute for Clinical & Molecular Virology, University of Erlangen-Nuremberg, Schlossgarten 4, 91054 Erlangen, Germany
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20
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Abstract
The history of the molecular biology of cytomegaloviruses from the purification of the virus and the viral DNA to the cloning and expression of the viral genes is reviewed. A key genetic element of cytomegalovirus (the CMV promoter) contributed to our understanding of eukaryotic cell molecular biology and to the development of lifesaving therapeutic proteins. The study of the molecular biology of cytomegaloviruses also contributed to the development of antivirals to control the viral infection.
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Affiliation(s)
- Mark F Stinski
- Department of Microbiology, Carver College of Medicine, University of Iowa, 3-701 BSB, 51 Newton Rd., Iowa City, IA, 52242, USA,
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21
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Matlaf LA, Harkins LE, Bezrookove V, Cobbs CS, Soroceanu L. Cytomegalovirus pp71 protein is expressed in human glioblastoma and promotes pro-angiogenic signaling by activation of stem cell factor. PLoS One 2013; 8:e68176. [PMID: 23861869 PMCID: PMC3702580 DOI: 10.1371/journal.pone.0068176] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 05/24/2013] [Indexed: 12/28/2022] Open
Abstract
Glioblastoma multiforme (GBM) is a highly malignant primary central nervous system neoplasm characterized by tumor cell invasion, robust angiogenesis, and a mean survival of 15 months. Human cytomegalovirus (HCMV) infection is present in >90% of GBMs, although the role the virus plays in GBM pathogenesis is unclear. We report here that HCMV pp71, a viral protein previously shown to promote cell cycle progression, is present in a majority of human GBMs and is preferentially expressed in the CD133+, cancer stem-like cell population. Overexpression of pp71 in adult neural precursor cells resulted in potent induction of stem cell factor (SCF), an important pro-angiogenic factor in GBM. Using double immunofluorescence, we demonstrate in situ co-localization of pp71 and SCF in clinical GBM specimens. pp71 overexpression in both normal and transformed glial cells increased SCF secretion and this effect was specific, since siRNA mediated knockdown of pp71 or treatment with the antiviral drug cidofovir resulted in decreased expression and secretion of SCF by HCMV-infected cells. pp71- induced upregulation of SCF resulted in downstream activation of its putative endothelial cell receptor, c-kit, and angiogenesis as measured by increased capillary tube formation in vitro. We demonstrate that pp71 induces a pro-inflammatory response via activation of NFΚB signaling which drives SCF expression. Furthermore, we show that pp71 levels and NFKB activation are selectively augmented in the mesenchymal subtype of human GBMs, characterized by worst patient outcome, suggesting that HCMV pp71-induced paracrine signaling may contribute to the aggressive phenotype of this human malignancy.
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Affiliation(s)
- Lisa A. Matlaf
- California Pacific Medical Center Research Institute, San Francisco, California, United States of America
| | - Lualhati E. Harkins
- Birmingham Veterans Administration Hospital, Birmingham, Alabama, United States of America
| | - Vladimir Bezrookove
- California Pacific Medical Center Research Institute, San Francisco, California, United States of America
| | - Charles S. Cobbs
- California Pacific Medical Center Research Institute, San Francisco, California, United States of America
- University of California San Francisco, Department of Neurological Surgery, San Francisco, California, United States of America
| | - Liliana Soroceanu
- California Pacific Medical Center Research Institute, San Francisco, California, United States of America
- * E-mail:
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22
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Human cytomegalovirus pUL29/28 and pUL38 repression of p53-regulated p21CIP1 and caspase 1 promoters during infection. J Virol 2012; 87:2463-74. [PMID: 23236067 DOI: 10.1128/jvi.01926-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
During infection by human cytomegalovirus (HCMV), the tumor suppressor protein p53, which promotes efficient viral gene expression, is stabilized. However, the expression of numerous p53-responsive cellular genes is not upregulated. The molecular mechanism used to manipulate the transcriptional activity of p53 during infection remains unclear. The HCMV proteins IE1, IE2, pUL44, and pUL84 likely contribute to the regulation of p53. In this study, we used a discovery-based approach to identify the protein targets of the HCMV protein pUL29/28 during infection. Previous studies have demonstrated that pUL29/28 regulates viral gene expression by interacting with the chromatin remodeling complex NuRD. Here, we observed that pUL29/28 also associates with p53, an additional deacetylase complex, and several HCMV proteins, including pUL38. We confirmed the interaction between p53 and pUL29/28 in both the presence and absence of infection. HCMV pUL29/28 with pUL38 altered the activity of the 53-regulatable p21CIP1 promoter. During infection, pUL29/28 and pUL38 contributed to the inhibition of p21CIP1 as well as caspase 1 expression. The expression of several other p53-regulating genes was not altered. Infection using a UL29-deficient virus resulted in increased p53 binding and histone H3 acetylation at the responsive promoters. Furthermore, expression of pUL29/28 and its interacting partner pUL38 contributed to an increase in the steady-state protein levels of p53. This study identified two additional HCMV proteins, pUL29/28 and pUL38, which participate in the complex regulation of p53 transcriptional activity during infection.
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23
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Kwon Y, Kim MN, Young Choi E, Heon Kim J, Hwang ES, Cha CY. Inhibition of p53 transcriptional activity by human cytomegalovirus UL44. Microbiol Immunol 2012; 56:324-31. [PMID: 22376288 DOI: 10.1111/j.1348-0421.2012.00446.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Human cytomegalovirus (HCMV) stimulates cellular synthesis of DNA and proteins and induces transition of the cell cycle from G(1) to S and G(2) /M phase, in spite of increased amounts of p53 in the infected cells. The immediate early protein IE2-86 kDa (IE86) tethers a transcriptional repression domain to p53; however, its repression of p53 function is not enough to abrogate the G(1) checkpoint function of p53. Other HCMV proteins that suppress the activity of p53 were investigated in this study. Of the HCMV proteins that bind to p53 when assessed by immunoprecipitation and immunoblot analysis, HCMV UL44 was chosen as a candidate protein. It was found that reporter gene containing p53 consensus sequence was activated by transfection with wild type p53, but when plasmids of p53 with IE86 or UL44 were co-transfected, p53 transcriptional activity was decreased to 3-7% of the p53 control in a dose-dependent manner. When the deletion mutant of UL44 was co-transected with p53, the carboxyl one-third portion of UL44 had little effect on inhibition of p53 transcriptional activity. The amount of mRNA p21 was measured in H1299 by real time PCR after transfection of the combination of p53 and UL44 vectors and it was found that p21 transcription by p53 was inhibited dose-dependently by UL44. Increased G0/G1 and decreased S phases in p53 wild type-transfected H1299 cells were recovered to the level of p53 mutant type-transfected ones by the additional transfection of UL44 in a dose-dependent manner. In conclusion, the transcriptional activity of p53 is suppressed by UL44 as well as by IE86.
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Affiliation(s)
- Yejin Kwon
- Department of Microbiology and Immunology, Seoul National University Medical Research Center, Seoul 110-799, Korea
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24
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Chen HP, Jiang JK, Chen CY, Chou TY, Chen YC, Chang YT, Lin SF, Chan CH, Yang CY, Lin CH, Lin JK, Cho WL, Chan YJ. Human cytomegalovirus preferentially infects the neoplastic epithelium of colorectal cancer: a quantitative and histological analysis. J Clin Virol 2012; 54:240-4. [PMID: 22595308 DOI: 10.1016/j.jcv.2012.04.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 03/19/2012] [Accepted: 04/17/2012] [Indexed: 12/12/2022]
Abstract
BACKGROUND It has long been suggested that human cytomegalovirus (HCMV) might be involved in human oncogenesis. However, whether HCMV was associated with colorectal cancer (CRC) was still controversial. OBJECTIVE To clarify whether HCMV specifically infects the tumorous tissue of CRC. STUDY DESIGN Paired tumor and adjacent non-neoplastic CRC specimens were collected from 163 patients. HCMV DNA was detected and quantified through PCR and quantitative real-time PCR. Virus location was determined by in situ hybridization (ISH) of formalin-fixed paraffin-embedded tissue sections with an HCMV-specific probe. RESULTS By PCR, HCMV DNA was detected in 42.3% (69/163) of the tumor specimens, while only 5.6%(14/163) samples of adjacent non-neoplastic tissue were positive for HCMV (p<0.0001). Quantitative real-time PCR in 54 sample pairs revealed significantly higher viral copies in the tumor specimens than the adjacent non-neoplastic tissue specimens (p<0.001). By ISH, the nucleic acids of HCMV were detected in the cytoplasm of neoplastic epithelium. No hybridization was detected in the inflammatory infiltrates, submucosa, or other stromal tissues. CONCLUSIONS HCMV preferentially infects the tumor epithelium of CRC. How the virus subsists in and interacts with the microenvironment of tumor epithelium of CRC should be studied.
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Affiliation(s)
- Hsin-Pai Chen
- Department of Medicine, National Yang-Ming University Hospital, Yilan, Taiwan
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25
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Evans Braun T, Poole E, Sinclair J. Depletion of cellular pre-replication complex factors results in increased human cytomegalovirus DNA replication. PLoS One 2012; 7:e36057. [PMID: 22586460 PMCID: PMC3346814 DOI: 10.1371/journal.pone.0036057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 03/29/2012] [Indexed: 12/11/2022] Open
Abstract
Although HCMV encodes many genes required for the replication of its DNA genome, no HCMV-encoded orthologue of the origin binding protein, which has been identified in other herpesviruses, has been identified. This has led to speculation that HCMV may use other viral proteins or possibly cellular factors for the initiation of DNA synthesis. It is also unclear whether cellular replication factors are required for efficient replication of viral DNA during or after viral replication origin recognition. Consequently, we have asked whether cellular pre-replication (pre-RC) factors that are either initially associated with cellular origin of replication (e.g. ORC2), those which recruit other replication factors (e.g. Cdt1 or Cdc6) or those which are subsequently recruited (e.g. MCMs) play any role in the HCMV DNA replication. We show that whilst RNAi-mediated knock-down of these factors in the cell affects cellular DNA replication, as predicted, it results in concomitant increases in viral DNA replication. These data show that cellular factors which initiate cellular DNA synthesis are not required for the initiation of replication of viral DNA and suggest that inhibition of cellular DNA synthesis, in itself, fosters conditions which are conducive to viral DNA replication.
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Affiliation(s)
- Tamara Evans Braun
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - Emma Poole
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - John Sinclair
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Cambridge, United Kingdom
- * E-mail:
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26
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RNA interference-mediated targeting of human cytomegalovirus immediate-early or early gene products inhibits viral replication with differential effects on cellular functions. J Virol 2012; 86:5660-73. [PMID: 22438545 DOI: 10.1128/jvi.06338-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Viral drug toxicity, resistance, and an increasing immunosuppressed population warrant continued research into new avenues for limiting diseases associated with human cytomegalovirus (HCMV). In this study, a small interfering RNA (siRNA), siX3, was designed to target coding sequences within shared exon 3 of UL123 and UL122 transcripts encoding IE1 and IE2 immediate-early proteins of HCMV. Pretreatment of cells with siX3 reduced the levels of viral protein expression, DNA replication, and progeny virus production compared to control siRNA. Two siRNAs against UL54 and overlapping transcripts (UL55-57) were compared to siX3 in HCMV infection and were also found to be effective at inhibiting HCMV replication. Further investigation into the effects of the siRNAs on viral replication showed that pretreatment with each of the siRNAs resulted in an inhibition in the formation of mature replication compartments. The ability of these siRNAs to prevent or reduce certain cytopathic effects associated with HCMV infection was also examined. Infected cells pretreated with siX3, but not siUL54, retained promyelocytic leukemia (PML) protein in cellular PML bodies, an essential component of this host intrinsic antiviral defense. DNA damage response proteins, which are localized in nuclear viral replication compartments, were reduced in the siX3- and siUL54-treated cells. siX3, but not siUL54, prevented DNA damage response signaling early after infection. Therapeutic efficacy was demonstrated by treating cells with siRNAs after HCMV replication had commenced. Together, these findings suggest that siRNAs targeting exon 3 of the major IE genes or the UL54-57 transcripts be further studied for their potential development into anti-HCMV therapeutics.
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27
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Dziurzynski K, Chang SM, Heimberger AB, Kalejta RF, McGregor Dallas SR, Smit M, Soroceanu L, Cobbs CS. Consensus on the role of human cytomegalovirus in glioblastoma. Neuro Oncol 2012; 14:246-55. [PMID: 22319219 DOI: 10.1093/neuonc/nor227] [Citation(s) in RCA: 216] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The human cytomegalovirus (HCMV) and glioma symposium was convened on April 17, 2011 in Washington, DC, and was attended by oncologists and virologists involved in studying the relationship between HCMV and gliomas. The purpose of the meeting was to reach a consensus on the role of HCMV in the pathology of gliomas and to clarify directions for future research. First, the group summarized data that describe how HCMV biology overlaps with the key pathways of cancer. Then, on the basis of published data and ongoing research, a consensus was reached that there is sufficient evidence to conclude that HCMV sequences and viral gene expression exist in most, if not all, malignant gliomas, that HCMV could modulate the malignant phenotype in glioblastomas by interacting with key signaling pathways; and that HCMV could serve as a novel target for a variety of therapeutic strategies. In summary, existing evidence supports an oncomodulatory role for HCMV in malignant gliomas, but future studies need to focus on determining the role of HCMV as a glioma-initiating event.
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Affiliation(s)
- Kristine Dziurzynski
- Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, 1400 Holcombe Blvd., Unit 442, Houston, TX 77030, USA.
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28
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E X, Pickering MT, Debatis M, Castillo J, Lagadinos A, Wang S, Lu S, Kowalik TF. An E2F1-mediated DNA damage response contributes to the replication of human cytomegalovirus. PLoS Pathog 2011; 7:e1001342. [PMID: 21589897 PMCID: PMC3093362 DOI: 10.1371/journal.ppat.1001342] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 04/11/2011] [Indexed: 12/02/2022] Open
Abstract
DNA damage resulting from intrinsic or extrinsic sources activates DNA damage responses (DDRs) centered on protein kinase signaling cascades. The usual consequences of inducing DDRs include the activation of cell cycle checkpoints together with repair of the damaged DNA or induction of apoptosis. Many DNA viruses elicit host DDRs during infection and some viruses require the DDR for efficient replication. However, the mechanism by which DDRs are activated by viral infection is poorly understood. Human cytomegalovirus (HCMV) infection induces a DDR centered on the activation of ataxia telangiectasia mutated (ATM) protein kinase. Here we show that HCMV replication is compromised in cells with inactivated or depleted ATM and that ATM is essential for the host DDR early during infection. Likewise, a downstream target of ATM phosphorylation, H2AX, also contributes to viral replication. The ATM-dependent DDR is detected as discrete, nuclear γH2AX foci early in infection and can be activated by IE proteins. By 24 hpi, γH2AX is observed primarily in HCMV DNA replication compartments. We identified a role for the E2F1 transcription factor in mediating this DDR and viral replication. E2F1, but not E2F2 or E2F3, promotes the accumulation of γH2AX during HCMV infection or IE protein expression. Moreover, E2F1 expression, but not the expression of E2F2 or E2F3, is required for efficient HCMV replication. These results reveal a novel role for E2F1 in mediating an ATM-dependent DDR that contributes to viral replication. Given that E2F activity is often deregulated by infection with DNA viruses, these observations raise the possibility that an E2F1-mediated mechanism of DDR activation may be conserved among DNA viruses. As intracellular parasites, viruses often redirect cellular pathways to facilitate their own replication. Infection by DNA viruses often lead to the activation of host DNA damage response pathways, which normally function to repair damage to host chromosomes. Some DNA viruses depend on this infection-induced DNA damage response to efficiently replicate. How infection activates the DNA damage response is poorly understood. To address this limitation, we first determined whether the DNA damage response affects the replication of human cytomegalovirus (HCMV) and then addressed how infection induces this response in cells. We find that HCMV infection results in a host DNA damage response centered on the Ataxia Telangiectasia Mutated (ATM) protein kinase. We also show that HCMV requires ATM for efficient replication. Unexpectedly, we find that the mechanism responsible for ATM activation is the expression of E2F1, a cellular transcription factor. Moreover, expression of E2F1, like ATM, is required for HCMV replication. These observations may be of fundamental importance because infection by most DNA viruses result in both E2F1 expression and an ATM-mediated DNA damage response.
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Affiliation(s)
- Xiaofei E
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Program in Immunology and Virology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Mary T. Pickering
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Michelle Debatis
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Jonathan Castillo
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Program in Immunology and Virology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Alexander Lagadinos
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Program in Immunology and Virology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Shixia Wang
- Program in Immunology and Virology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Laboratory of Nucleic Acid Vaccines, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Shan Lu
- Program in Immunology and Virology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Laboratory of Nucleic Acid Vaccines, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Timothy F. Kowalik
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Program in Immunology and Virology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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Harkins LE, Matlaf LA, Soroceanu L, Klemm K, Britt WJ, Wang W, Bland KI, Cobbs CS. Detection of human cytomegalovirus in normal and neoplastic breast epithelium. HERPESVIRIDAE 2010; 1:8. [PMID: 21429243 PMCID: PMC3063230 DOI: 10.1186/2042-4280-1-8] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 12/23/2010] [Indexed: 12/20/2022]
Abstract
Introduction Human cytomegalovirus (HCMV) establishes a persistent life-long infection, and can cause severe pathology in the fetus and the immunocompromised host[1]. Breast milk is the primary route of transmission in humans worldwide, and breast epithelium is thus a likely site of persistent infection and/or reactivation, though this phenomenon has not previously been demonstrated. Increasing evidence indicates HCMV infection can modulate signaling pathways associated with oncogenesis. We hypothesized that persistent HCMV infection occurs in normal adult breast epithelium and that persistent viral expression might be associated with normal and neoplastic ductal epithelium. Methods Surgical biopsy specimens of normal breast (n = 38) breast carcinoma (n = 39) and paired normal breast from breast cancer patients (n = 21) were obtained. Specimens were evaluated by immunohistochemistry, in situ hybridization, PCR and DNA sequencing for evidence of HCMV antigens and nucleic acids. Results We detected HCMV expression specifically in glandular epithelium in 17/27 (63%) of normal adult breast cases evaluated. In contrast, HCMV expression was evident in the neoplastic epithelium of 31/32 (97%) patients with ductal carcinoma in situ (DCIS) and infiltrating ductal carcinoma (IDC) cases evaluated (p = 0.0009). Conclusions These findings are the first to demonstrate that persistent HCMV infection occurs in breast epithelium in a significant percentage of normal adult females. HCMV expression was also evident in neoplastic breast epithelium in a high percentage of normal and neoplastic breast tissues obtained from breast cancer patients, raising the possibility that viral infection may be involved in the neoplastic process.
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Affiliation(s)
- Lualhati E Harkins
- Research Institute, California Pacific Medical Center, (475 Brannan St,, Suite 220) San Francisco CA, 94107, USA.
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Saha A, Kaul R, Murakami M, Robertson ES. Tumor viruses and cancer biology: Modulating signaling pathways for therapeutic intervention. Cancer Biol Ther 2010; 10:961-78. [PMID: 21084867 DOI: 10.4161/cbt.10.10.13923] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Tumor viruses have provided relatively simple genetic systems, which can be manipulated for understanding the molecular mechanisms of the cellular transformation process. A growing body of information in the tumor virology field provides several prospects for rationally targeted therapies. However, further research is needed to better understand the multiple mechanisms utilized by these viruses in cancer progression in order to develop therapeutic strategies. Initially viruses were believed to be associated with cancers as causative agents only in animals. It was almost half a century before the first human tumor virus, Epstein-Barr virus (EBV), was identified in 1964. Subsequently, several human tumor viruses have been identified including Kaposi sarcoma associated herpesvirus (KSHV), human Papillomaviruses (HPV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Human T lymphotropic virus (HTLV-1) and recently identified Merkel cell Polyomavirus (MCPyV). Tumor viruses are sub-categorized as either DNA viruses, which include EBV, KSHV, HPV, HBV, and MCPyV, or RNA viruses such as HCV and HTLV-1. Tumor-viruses induce oncogenesis through manipulating an array of different cellular pathways. These viruses initiate a series of cellular events, which lead to immortalization and proliferation of the infected cells by disrupting the mitotic checkpoint upon infection of the host cell. This is often accomplished by functional inhibition or proteasomal degradation of many tumor suppressor proteins by virally encoded gene products. The virally infected cells can either be eliminated via cell-mediated apoptosis or persist in a state of chronic infection. Importantly, the chronic persistence of infection by tumor viruses can lead to oncogenesis. This review discusses the major human tumor associated viruses and their ability to modulate numerous cell signaling pathways, which can be targeted for potential therapeutic approaches.
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Affiliation(s)
- Abhik Saha
- Department of Microbiology and Tumor Virology, University of Pennsylvania School of Medicine, Philadelphia, USA
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Alternative splicing of the human cytomegalovirus major immediate-early genes affects infectious-virus replication and control of cellular cyclin-dependent kinase. J Virol 2010; 85:804-17. [PMID: 21068259 DOI: 10.1128/jvi.01173-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The major immediate-early (MIE) gene locus of human cytomegalovirus (HCMV) is the master switch that determines the outcomes of both lytic and latent infections. Here, we provide evidence that alteration in the splicing of HCMV (Towne strain) MIE genes affects infectious-virus replication, movement through the cell cycle, and cyclin-dependent kinase activity. Mutation of a conserved 24-nucleotide region in MIE exon 4 increased the abundance of IE1-p38 mRNA and decreased the abundance of IE1-p72 and IE2-p86 mRNAs. An increase in IE1-p38 protein was accompanied by a slight decrease in IE1-p72 protein and a significant decrease in IE2-p86 protein. The mutant virus had growth defects, which could not be complemented by wild-type IE1-p72 protein in trans. The phenotype of the mutant virus could not be explained by an increase in IE1-p38 protein, but prevention of the alternate splice returned the recombinant virus to the wild-type phenotype. The lower levels of IE1-p72 and IE2-p86 proteins correlated with a delay in early and late viral gene expression and movement into the S phase of the cell cycle. Mutant virus-infected cells had significantly higher levels of cdk-1 expression and enzymatic activity than cells infected with wild-type virus. The mutant virus induced a round-cell phenotype that accumulated in the G(2)/M compartment of the cell cycle with condensation and fragmentation of the chromatin. An inhibitor of viral DNA synthesis increased the round-cell phenotype. The round cells were characteristic of an abortive viral infection.
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Dimitropoulou P, Caswell R, McSharry BP, Greaves RF, Spandidos DA, Wilkinson GWG, Sourvinos G. Differential relocation and stability of PML-body components during productive human cytomegalovirus infection: detailed characterization by live-cell imaging. Eur J Cell Biol 2010; 89:757-68. [PMID: 20599291 DOI: 10.1016/j.ejcb.2010.05.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 05/14/2010] [Accepted: 05/26/2010] [Indexed: 01/30/2023] Open
Abstract
In controlling the switch from latency to lytic infection, the immediate early (IE) genes lie at the core of herpesvirus pathogenesis. To image the 72kDa human cytomegalovirus (HCMV) major IE protein (IE1-72K), a recombinant virus encoding IE1 fused with EGFP was constructed. Using this construct, the IE1-EGFP fusion was detected at ND10 (PML-bodies) within 2h post infection (p.i.) and the complete disruption of ND10 imaged through to 6h p.i. HCMV genomes and IE2-86K protein could be detected adjacent to the slowly degrading IE1-72K/ND10 foci. IE1-72K associates with metaphase chromatin, recruiting both PML and STAT2. hDaxx, STAT1 and IE2-86K did not re-locate to metaphase chromatin; the fate of hDaxx is particularly important as this protein contributes to an intrinsic barrier to HCMV infection. While IE1-72K participates in a complex with chromatin, PML, STAT2 and Sp100, IE1-72K releases hDaxx from ND10 yet does not appear to remain associated with it.
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Affiliation(s)
- Panagiota Dimitropoulou
- Department of Virology, Faculty of Medicine, University of Crete, Heraklion 71003, Crete, Greece
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Kim J, Jung ES, Kwon Y, Choi EY, Jeong H, Kim S, Park CG, Kim SJ, Hwang ES. Infection of Porcine Cells with Human Herpesviruses. Transplant Proc 2010; 42:2134-7. [DOI: 10.1016/j.transproceed.2010.05.081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Human cytomegalovirus IE2 86 and IE2 40 proteins differentially regulate UL84 protein expression posttranscriptionally in the absence of other viral gene products. J Virol 2010; 84:5158-70. [PMID: 20200242 DOI: 10.1128/jvi.00090-10] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
It has previously been demonstrated that, during human cytomegalovirus infection, the viral IE2 86 and IE2 40 proteins are both important for the expression of an early-late viral protein, UL84. Here, we show that expression of the UL84 protein is enhanced upon cotransfection with either IE2 86 or IE2 40, although IE2 40 appears to play a more important role. The UL84 protein levels are tightly linked to the amount of IE2 40 present, but this does not appear to be true for IE2 86. RNA remains constant for all corresponding proteins, indicating posttranscriptional regulation of UL84. The first 105 amino acids of UL84 are necessary and sufficient for this phenotype, and this region is also required for an interaction with IE2 86 and IE2 40. Treatment with proteasome inhibitors shows that UL84 exhibits some proteasome-dependent degradation, and UL84 is not protected against this degradation when coexpressed with IE2 86 or IE2 40. UL84 also exhibits an inhibitory effect on IE2 86 and IE2 40 protein levels in these cotransfection assays. Further, we show that the amino acid sequence of UL84 is important for the enhancement governed by IE2 40. These results indicate that IE2 86, IE2 40, and UL84 serve to regulate protein expression in a posttranscriptional fashion and that this regulation is independent of other viral proteins.
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Paulus C, Nevels M. The human cytomegalovirus major immediate-early proteins as antagonists of intrinsic and innate antiviral host responses. Viruses 2009; 1:760-79. [PMID: 21994568 PMCID: PMC3185523 DOI: 10.3390/v1030760] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 11/04/2009] [Accepted: 11/05/2009] [Indexed: 12/21/2022] Open
Abstract
The major immediate-early (IE) gene of human cytomegalovirus (CMV) is believed to have a decisive role in acute infection and its activity is an important indicator of viral reactivation from latency. Although a variety of gene products are expressed from this region, the 72-kDa IE1 and the 86-kDa IE2 nuclear phosphoproteins are the most abundant and important. Both proteins have long been recognized as promiscuous transcriptional regulators. More recently, a critical role of the IE1 and IE2 proteins in counteracting non-adaptive host cell defense mechanisms has been revealed. In this review we will briefly summarize the available literature on IE1- and IE2-dependent mechanisms contributing to CMV evasion from intrinsic and innate immune responses.
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Affiliation(s)
- Christina Paulus
- Institute for Medical Microbiology and Hygiene, University of Regensburg, Franz-Josef-Strauss-Allee 11, D-93053 Regensburg, Germany; E-Mail:
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Human cytomegalovirus IE1-72 protein interacts with p53 and inhibits p53-dependent transactivation by a mechanism different from that of IE2-86 protein. J Virol 2009; 83:12388-98. [PMID: 19776115 DOI: 10.1128/jvi.00304-09] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Infection of host cells with human cytomegalovirus (HCMV) induces cell cycle dysregulation. Two HCMV immediate-early (IE) proteins, IE1-72 and IE2-86, are promiscuous transactivators that have been implicated in the dysregulatory events. Cellular p53 protein is accumulated to high levels in HCMV-infected cells, but the indicative marker of p53 transcriptional activity, p21, is markedly decreased. Both IE1-72 and IE2-86 were able to transactivate the p53 promoter and interact with p53 protein in DNA-transfected or HCMV-infected cells. HCMV UL84, a multiregulatory protein expressed in early periods of HCMV infection, also interacted with p53. HCMV IE1-72 prevented or disrupted p53 binding to p53-specific DNA sequences, while IE2-86 and/or UL84 enhanced p53 binding and induced supershift of this DNA-protein complex. Both HCMV IE1-72 and IE2-86 were able to inhibit p53-dependent transcriptional activation in plasmid-transfected cells. IE1-72, rather than IE2-86, was found to be responsible for p21 downregulation in HCMV-infected HEL cells. DNA transfection analysis using IE1-72 mutants revealed that exon 2/3 and the zinc finger region of IE1-72 are essential for IE1-72's effect on the repression of p53-dependent transcriptional activation. These data suggest that HCMV IE1-72 and/or IE2-86 transactivates the p53 promoter and induces p53 accumulation, but HCMV IE1-72 represses the p53 transactivation activity by a unique binding hindrance mechanism different from that of IE2-86. Thus, various modes of viral IE proteins and p53 interactions might result in multiple outcomes, such as stimulation of cellular DNA synthesis, cell cycle progression and cell cycle arrest, and prevention of program cell death.
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Xia L, Cao J, Huang X, Qin Q. Characterization of Singapore grouper iridovirus (SGIV) ORF086R, a putative homolog of ICP18 involved in cell growth control and virus replication. Arch Virol 2009; 154:1409-16. [PMID: 19629635 DOI: 10.1007/s00705-009-0457-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 07/02/2009] [Indexed: 11/28/2022]
Abstract
Singapore grouper iridovirus (SGIV), as a causative agent of serious systemic disease, causes significant economic losses in grouper aquaculture. In this study, a novel ICP18 homolog encoded by SGIV ORF086R was identified and characterized. Strikingly, ICP18 homologs can be found in all ranaviruses, but not in other sequenced large DNA viruses. SGIV ICP18 is an immediate-early gene and begins to be transcribed as early as 2 h post-infection (p.i.). Western blotting indicated that SGIV ICP18 is translated as early as 6 h p.i. and is a viral non-envelope protein. Subcellular localization analysis revealed that the SGIV ICP18 displays a finely punctate cytoplasmic pattern. Furthermore, overexpression of SGIV ICP18 can promote the growth of grouper embryonic cells (GP) and contribute to SGIV replication. These results should offer important insights into the pathogenesis of ranaviruses.
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Affiliation(s)
- Liqun Xia
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, 135 West Xingang Road, 510275, Guangzhou, China
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38
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Effect of inducible expressed human cytomegalovirus immediate early 86 protein on cell apoptosis. Biosci Biotechnol Biochem 2009; 73:1268-73. [PMID: 19502735 DOI: 10.1271/bbb.80722] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Human cytomegalovirus is a common human pathogen that can cause life-threatening disease under certain conditions. During infection of host cells, the virus expresses regulatory proteins such as IE72 and IE86 that are important for viral propagation. IE86 plays a critical role in the modulation of viral replication as well as host cell cycle control and apoptosis. In this study, a Tet-On system was used to quantify the effect of IE86 on apoptosis and p53 expression. Our results indicate that IE86 inhibits tumor necrosis factor (TNF)-alpha induced apoptosis and that the anti-apoptotic activity of this viral protein correlates with its expression levels. In addition, IE86 did not alter the mRNA level of p53. The system developed should provide a method for functional analysis of human cytomegalovirus (HCMV) IE86 protein.
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Yi F, Saha A, Murakami M, Kumar P, Knight JS, Cai Q, Choudhuri T, Robertson ES. Epstein-Barr virus nuclear antigen 3C targets p53 and modulates its transcriptional and apoptotic activities. Virology 2009; 388:236-47. [PMID: 19394062 DOI: 10.1016/j.virol.2009.03.027] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 03/09/2009] [Accepted: 03/21/2009] [Indexed: 01/17/2023]
Abstract
The p53 tumor suppressor gene is one of the most commonly mutated genes in human cancers and the corresponding encoded protein induces apoptosis or cell-cycle arrest at the G1/S checkpoint in response to DNA damage. To date, previous studies have shown that antigens encoded by human tumor viruses such as SV40 large T antigen, adenovirus E1A and HPV E6 interact with p53 and disrupt its functional activity. In a similar fashion, we now show that EBNA3C, one of the EBV latent antigens essential for the B-cell immortalization in vitro, interacts directly with p53. Additionally, we mapped the interaction of EBNA3C with p53 to the C-terminal DNA-binding and the tetramerization domain of p53, and the region of EBNA3C responsible for binding to p53 was mapped to the N-terminal domain of EBNA3C (residues 130-190), previously shown to interact with a number of important cell-cycle components, specifically SCF(Skp2), cyclin A, and cMyc. Furthermore, we demonstrate that EBNA3C substantially represses the transcriptional activity of p53 in luciferase based reporter assays, and rescues apoptosis induced by ectopic p53 expression in SAOS-2 (p53(-/-)) cells. Interestingly, we also show that the DNA-binding ability of p53 is diminished in the presence of EBNA3C. Thus, the interaction between the p53 and EBNA3C provides new insights into the mechanism(s) by which the EBNA3C oncoprotein can alter cellular gene expression in EBV associated human cancers.
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Affiliation(s)
- Fuming Yi
- Department of Microbiology and Tumor Virology Program, Abramson Comprehensive Cancer Center, University of Pennsylvania Medical School, 201E Johnson Pavilion, 3610 Hamilton Walk, PA 19104, USA
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Koh K, Lee K, Ahn JH, Kim S. Human cytomegalovirus infection downregulates the expression of glial fibrillary acidic protein in human glioblastoma U373MG cells: identification of viral genes and protein domains involved. J Gen Virol 2009; 90:954-962. [PMID: 19264642 DOI: 10.1099/vir.0.006486-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Human cytomegalovirus (HCMV) has tropism for glial cells, among many other cell types. It was reported previously that the stable expression of HCMV immediate-early protein 1 (IE1) could dramatically reduce the RNA level of glial fibrillary acidic protein (GFAP), an astroglial cell-specific intermediate filament protein, which is progressively lost with an increase in glioma malignancy. To understand this phenomenon in the context of virus infection, a human glioblastoma cell line, U373MG, was infected with HCMV (strain AD169 or Towne). The RNA level of GFAP was reduced by more than 10-fold at an m.o.i. of 3 at 48 h post-infection, whilst virus treated with neutralizing antibody C23 or with UV light had a much-reduced effect. Treatment of infected cells with ganciclovir did not prevent HCMV-mediated downregulation of GFAP. Although the expression of GFAP RNA is downregulated in IE1-expressing cells, a mutant HCMV strain lacking IE1 still suppressed GFAP, indicating that other IE proteins may be involved. IE2 is also proposed to be involved in GFAP downregulation, as an adenoviral vector expressing IE2 could also reduce the RNA level of GFAP. Data from the mutational analysis indicated that HCMV infection might affect the expression of this structural protein significantly, primarily through the C-terminal acidic region of the IE1 protein.
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Affiliation(s)
- Kyungmi Koh
- School of Biological Sciences, Seoul National University, Seoul 151-747, Republic of Korea
| | - Karim Lee
- School of Biological Sciences, Seoul National University, Seoul 151-747, Republic of Korea
| | - Jin-Hyun Ahn
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Kyonggido 440-746, Republic of Korea
| | - Sunyoung Kim
- School of Biological Sciences, Seoul National University, Seoul 151-747, Republic of Korea
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Hume AJ, Kalejta RF. Regulation of the retinoblastoma proteins by the human herpesviruses. Cell Div 2009; 4:1. [PMID: 19146698 PMCID: PMC2636798 DOI: 10.1186/1747-1028-4-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 01/15/2009] [Indexed: 01/21/2023] Open
Abstract
Viruses are obligate intracellular parasites that alter the environment of infected cells in order to replicate more efficiently. One way viruses achieve this is by modulating cell cycle progression. The main regulators of progression out of G0, through G1, and into S phase are the members of the retinoblastoma (Rb) family of tumor suppressors. Rb proteins repress the transcription of genes controlled by the E2F transcription factors. Because the expression of E2F-responsive genes is required for cell cycle progression into the S phase, Rb arrests the cell cycle in G0/G1. A number of viral proteins directly target Rb family members for inactivation, presumably to create an environment more hospitable for viral replication. Such viral proteins include the extensively studied oncoproteins E7 (from human papillomavirus), E1A (from adenovirus), and the large T (tumor) antigen (from simian virus 40). Elucidating how these three viral proteins target and inactivate Rb has proven to be an invaluable approach to augment our understanding of both normal cell cycle progression and carcinogenesis. In addition to these proteins, a number of other virally-encoded inactivators of the Rb family have subsequently been identified including a surprising number encoded by human herpesviruses. Here we review how the human herpesviruses modulate Rb function during infection, introduce the individual viral proteins that directly or indirectly target Rb, and speculate about what roles Rb modulation by these proteins may play in viral replication, pathogenesis, and oncogenesis.
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Affiliation(s)
- Adam J Hume
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, WI 53706-1596, USA.
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Moorman NJ, Cristea IM, Terhune SS, Rout MP, Chait BT, Shenk T. Human cytomegalovirus protein UL38 inhibits host cell stress responses by antagonizing the tuberous sclerosis protein complex. Cell Host Microbe 2008; 3:253-62. [PMID: 18407068 DOI: 10.1016/j.chom.2008.03.002] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Revised: 01/29/2008] [Accepted: 03/05/2008] [Indexed: 12/19/2022]
Abstract
Human cytomegalovirus proteins alter host cells to favor virus replication. These viral proteins include pUL38, which prevents apoptosis. To characterize the mode of action of pUL38, we modified the viral genome to encode an epitope-tagged pUL38 and used rapid immunoaffinity purification to isolate pUL38-interacting host proteins, which were then identified by mass spectrometry. One of the cellular proteins identified was TSC2, a constituent of the tuberous sclerosis tumor suppressor protein complex (TSC1/2). TSC1/2 integrates stress signals and regulates the mammalian target of rapamycin complex 1 (mTORC1), a protein complex that responds to stress by limiting protein synthesis and cell growth. We showed that pUL38 interacts with TSC1 and TSC2 in cells infected with wild-type cytomegalovirus. Furthermore, TSC1/2 failed to regulate mTORC1 in cells expressing pUL38, and these cells exhibited the enlarged size characteristic of cytomegalovirus infection. Thus, pUL38 supports virus replication at least in part by blocking cellular responses to stress.
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Affiliation(s)
- Nathaniel J Moorman
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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Cobbs CS, Soroceanu L, Denham S, Zhang W, Kraus MH. Modulation of oncogenic phenotype in human glioma cells by cytomegalovirus IE1-mediated mitogenicity. Cancer Res 2008; 68:724-30. [PMID: 18245472 DOI: 10.1158/0008-5472.can-07-2291] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent evidence indicates that human cytomegalovirus (HCMV) infection occurs in a high percentage of human malignant gliomas in vivo, as the HCMV immediate early-1 (IE1) protein is detected in >90% of these tumors. The HCMV IE1 protein is essential for viral infection and has potent trans-activating and oncomodulatory properties. To investigate a potential role of HCMV in glioma biology, we stably expressed the HCMV IE1 gene product in immortalized and malignant human glial cells. Here we show that stable IE1 expression can differentially affect the growth of human glioblastoma cells, resulting in either growth proliferation or arrest. IE1 expression led to dysregulation of phosphatidylinositol 3-kinase/AKT activity, Rb phosphorylation, and expression of the p53 family of proteins. In U87 and U118 glioblastoma cells, IE1 induced cellular proliferation paralleled by reduction in steady-state expression level of Rb and p53 family proteins (including p53, p63, or p73) and simultaneous induction of the phosphatidylinositol 3-kinase/AKT signaling pathway. In contrast, IE1 expression in LN229 and U251 glioblastoma cells and immortalized human astrocytes was associated with increased expression of p53 family proteins, accompanied by growth arrest or lack of enhanced proliferation. Moreover, IE1 promoted cell cycle entry and DNA synthesis of human glioma cells on both stable expression in tumor-derived cell lines as well as transient expression in primary glioblastoma cells. These findings indicate that HCMV IE1 can significantly affect important oncogenic signaling pathways in glioblastoma cells.
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Affiliation(s)
- Charles S Cobbs
- Department of Surgery, Division of Neurosurgery, University of Alabama School of Medicine, Birmingham, Alabama, USA.
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Abstract
Human cytomegalovirus (HCMV) has evolved numerous strategies to commandeer the host cell for producing viral progeny. The virus manipulates host cell cycle pathways from the early stages of infection to stimulate viral DNA replication at the expense of cellular DNA synthesis. At the same time, cell cycle checkpoints are by-passed, preventing apoptosis and allowing sufficient time for the assembly of infectious virus.
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Affiliation(s)
- V Sanchez
- Deaprtment of Microbial and Molecular Pathogenesis, Texas A&M Health Science Center, College Station, TX 77843-1266, USA
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Casavant NC, Luo MH, Rosenke K, Winegardner T, Zurawska A, Fortunato EA. Potential role for p53 in the permissive life cycle of human cytomegalovirus. J Virol 2006; 80:8390-401. [PMID: 16912290 PMCID: PMC1563868 DOI: 10.1128/jvi.00505-06] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Infection of primary fibroblasts with human cytomegalovirus (HCMV) causes a rapid stabilization of the cellular protein p53. p53 is a major effector of the cellular damage response, and activation of this transcription factor can lead either to cell cycle arrest or to apoptosis. Viruses employ many tactics to avoid p53-mediated effects. One method HCMV uses to counteract p53 is sequestration into its viral replication centers. In order to determine whether or not HCMV benefits from this sequestration, we infected a p53(-/-) fibroblast line. We find that although these cells are permissive for viral infection, several parameters are substantially altered compared to wild-type (wt) fibroblasts. p53(-/-) cells show delayed and decreased accumulation of infectious viral particles compared to control fibroblasts, with the largest difference of 100-fold at 72 h post infection (p.i.) and peak titers decreased by approximately 10- to 20-fold at 144 h p.i. Viral DNA accumulation is also delayed and somewhat decreased in p53(-/-) cells; however, on average, levels of DNA are not more than fivefold lower than wt at any time p.i. and thus cannot account entirely for the observed differences in titers. In addition, there are delays in the expression of several key viral proteins, including the early replication protein UL44 and some of the late structural proteins, pp28 (UL99) and MCP (UL86). UL44 localization also indicates delayed formation and maturation of the replication centers throughout the course of infection. Localization of the major tegument protein pp65 (UL83) is also altered in these p53(-/-) cells. Partial reconstitution of the p53(-/-) cells with a wt copy of p53 returns all parameters toward wt, while reconstitution with mutant p53 does not. Taken together, our data suggest that wt p53 enhances the ability of HCMV to replicate and produce high concentrations of infectious virions in permissive cells.
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Affiliation(s)
- N C Casavant
- Department of Microbiology, Molecular Biology and Biochemistry and The Center for Reproductive Biology, University of Idaho, Moscow, 83844-3052, USA
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Poltermann S, Schlehofer B, Steindorf K, Schnitzler P, Geletneky K, Schlehofer JR. Lack of association of herpesviruses with brain tumors. J Neurovirol 2006; 12:90-9. [PMID: 16798670 DOI: 10.1080/13550280600654573] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Gliomas are the most frequent primary brain tumors in humans. Many studies have been carried out on their etiology; however, the only confirmed risk factors are hereditary predisposing conditions and high dose of ionizing radiation. Recently, human cytomegalovirus (HCMV) gene products and nucleic acids were reported to be present in all of 27 glioma samples investigated in contrast to other brain tissues, and it was hypothesized that HCMV might play a role in glioma pathogenesis. To evaluate these findings, samples of 40 gliomas, 31 meningiomas, and 6 acoustic neurinomas (ACNs) were analyzed for the presence of HCMV macromolecules using polymerase chain reaction (PCR) and immunohistochemistry. Additionally, corresponding blood samples from 72 patients were analyzed for the presence of HCMV DNA to check for a possible contamination of tumor tissues with HCMV-infected blood cells. No HCMV DNA sequences were found, neither in brain tumor tissues nor in corresponding blood samples. Immunohistochemistry did not detect HCMV-specific proteins. Addressing a possible role of other herpesviruses as has been suggested in seroepidemiological studies, seroprevalence of antibodies to HCMV, herpes simplex virus (HSV), Epstein-Barr virus (EBV), and varicella-zoster virus (VZV) were determined by enzyme-linked immunosorbent assay (ELISA). Serological analyses of brain tumor patients showed no significant differences in the prevalences of antibodies to HCMV, HSV, EBV, or VZV compared to the general population. Thus, the data of the present study do not support the hypothesis of an association of herpesviruses with the development of primary brain tumors.
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Affiliation(s)
- S Poltermann
- Unit of Environmental Epidemiology, German Cancer Research Center, Heidelberg, Germany
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Frame FM, Rogoff HA, Pickering MT, Cress WD, Kowalik TF. E2F1 induces MRN foci formation and a cell cycle checkpoint response in human fibroblasts. Oncogene 2006; 25:3258-66. [PMID: 16434972 DOI: 10.1038/sj.onc.1209352] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2005] [Revised: 11/07/2005] [Accepted: 11/07/2005] [Indexed: 11/09/2022]
Abstract
Deregulation of the Rb/E2F pathway in human fibroblasts results in an E2F1-mediated apoptosis dependent on Atm, Nbs1, Chk2 and p53. Here, we show that E2F1 expression results in MRN foci formation, which is independent of the Nbs1 interacting region and the DNA-binding domain of E2F1. E2F1-induced MRN foci are similar to irradiation-induced foci (IRIF) that result from double-strand DNA breaks because they correlate with 53BP1 and gammaH2AX foci, do not form in NBS cells, do form in AT cells and do not correlate with cell cycle entry. In fact, we find that in human fibroblasts deregulated E2F1 causes a G1 arrest, blocking serum-induced cell cycle progression, in part through an Nbs1/53BP1/p53/p21(WAF1/CIP1) checkpoint pathway. This checkpoint protects against apoptosis because depletion of 53BP1 or p21(WAF1/CIP1) increases both the rate and extent of apoptosis. Nbs1 and p53 contribute to both checkpoint and apoptosis pathways. These results suggest that E2F1-induced foci generate a cell cycle checkpoint that, with sustained E2F1 activity, eventually yields to apoptosis. Uncontrolled proliferation due to Rb/E2F deregulation as well as inactivation of both checkpoint and apoptosis programs would then be required for transformation of normal cells to tumor cells.
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Affiliation(s)
- F M Frame
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, 01655, USA
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Lam V, Boehme KW, Compton T, Yin J. Spatial patterns of protein expression in focal infections of human cytomegalovirus. Biotechnol Bioeng 2006; 93:1029-39. [PMID: 16506244 DOI: 10.1002/bit.20786] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Human cytomegalovirus (HCMV) is a medically significant human pathogen that infects a wide range of cell and tissue types. During infection, HCMV activates a variety of signal transduction pathways that induce profound changes in cellular processes and dramatically affect cellular gene expression patterns. To better define how these virus-host interactions affect the local microenvironment and influence the spatial and temporal spread of HCMV, we initiated HCMV focal infections on normal human dermal fibroblast monolayers and monitored viral gene expression patterns and infection spread over 45 days. To establish baseline temporal measurements of HCMV infection and spread in cell monolayers, we characterized the influence of three experimental variables on viral gene expression: cell plating density, the presence of serum, and neutralization of cellular antiviral responses with an antibody against interferon-beta. We found that high cell plating density or the inclusion of serum correlated with enhanced HCMV infection spread. Dramatic differences in the expression pattern of the viral immediate early 2 (IE2) gene were observed under these conditions as compared to low plating density or the absence of serum. In the latter case round, uniform foci were observed with a clear wave of IE2 expression visible in advance of a late stage viral protein, envelope glycoprotein B. By contrast, larger irregular foci with arms of IE2 expression were observed in the presence of serum. Addition of the antibody had little effect on the rate of spread, which is consistent with the knowledge that HCMV represses antiviral responses during infection. This experimental system provides a useful means to visualize and quantify complex virus-host interactions.
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Affiliation(s)
- Vy Lam
- Department of Chemical and Biological Engineering, 1415 Engineering Dr., University of Wisconsin, Madison, USA
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Nie X, Fang F, Li H, Dong Y, Zhou Y, Zhen H, Liu Z, Li G. Effects of human cytomegalovirus infection on apoptosis and expression of apoptosis-regulating factors. JOURNAL OF HUAZHONG UNIVERSITY OF SCIENCE AND TECHNOLOGY. MEDICAL SCIENCES = HUA ZHONG KE JI DA XUE XUE BAO. YI XUE YING DE WEN BAN = HUAZHONG KEJI DAXUE XUEBAO. YIXUE YINGDEWEN BAN 2006; 25:480-3. [PMID: 16463650 DOI: 10.1007/bf02895993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The present study aimed to find out dynamic changes of apoptosis in human cytomegalovirus (HCMV) infected cells and the influence of HCMV infection on activation of caspase-3 and the expression of apoptosis-regulating genes, bcl-2 and fas mRNA. The sequential changes of apoptotic cell rate in high and low MOI (MOI = 2.5 and 0.25 respectively) of HCMV infected human embryonic lung fibroblasts (HELFs) at 1 h, 12 h, 24 h, 36 h, 48 h, 72 h and 96 h post-infection were measured by flow cytometry. The expression levels of caspase-3 protein and bcl-2 and fas mRNA in HCMV infected cells (MOI = 0.25) at 72 h post-infection were detected by Western blot and in situ hybridization methods, respectively. It was found that the ratio of apoptotic cells in normal controls was consistently lower, but the rates in low and high MOI infected cells were gradually increased with time prolonged, reached peak at 96 h (8.85%) and 72 h (25.63%), respectively. By Western blot analysis, only a narrow band of 32 kD (1 kD = 0.992 1 ku) procaspase-3 was found in normal cells, but a wider procaspase-3 band and a much wider band of 17 kD proteins (p17) appeared in the infected cells. Meanwhile, the expression of bcl-2 mRNA was higher and that of fas mRNA was lower in the normal HELF cells, whereas there were significantly lower bcl-2 mRNA and higher fas mRNA expression levels in HCMV infected cells. It was concluded that HCMV was a stronger inducer of apoptosis in HELF cells. Caspase-3, as the marker of undergoing apoptosis, was expressed increasingly and activated in the infected cells, indicating its action in HCMV-inducing apoptosis. Down-regulating bcl-2 mRNA expression and up-regulating fas mRNA expression were also involved in the mechanism of HCMV-induced apoptosis.
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Affiliation(s)
- Xingcao Nie
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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Rosenke K, Samuel MA, McDowell ET, Toerne MA, Fortunato EA. An intact sequence-specific DNA-binding domain is required for human cytomegalovirus-mediated sequestration of p53 and may promote in vivo binding to the viral genome during infection. Virology 2006; 348:19-34. [PMID: 16455125 DOI: 10.1016/j.virol.2005.12.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Revised: 08/12/2005] [Accepted: 12/12/2005] [Indexed: 11/23/2022]
Abstract
The p53 protein is stabilized during infection of primary human fibroblasts with human cytomegalovirus (HCMV). However, the p53 in HCMV-infected cells is unable to activate its downstream targets. HCMV accomplishes this inactivation, at least in part, by sequestering p53 into viral replication centers within the cell's nucleus soon after they are established. In order to better understand the interplay between HCMV and p53 and the mechanism of sequestration, we constructed a panel of mutant p53-GFP fusion constructs for use in transfection/infection experiments. These mutants affected several post-translational modification sites and several sites within the central sequence-specific DNA-binding domain of the protein. Two categories of p53 sequestration were observed when the mutant constructs were transfected into primary fibroblasts and then infected at either high or low multiplicity. The first category, including all of the post-translational modification mutants, showed sequestration comparable to a wild-type (wt) control, while the second category, mutants affecting the DNA-binding core, were not specifically sequestered above control GFP levels. This suggested that the DNA-binding ability of the protein was required for sequestration. When the HCMV genome was analyzed for p53 consensus binding sites, 21 matches were found, which localized either to the promoters or the coding regions of viral proteins involved in DNA replication and processing as well as structural proteins. An analysis of in vivo binding to these identified sites via chromatin immunoprecipitation assays revealed differential binding to several of the sites over the course of infection.
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Affiliation(s)
- Kyle Rosenke
- University of Idaho, Department of Microbiology, Molecular Biology and Biochemistry and Center for Reproductive Biology, Moscow, ID 83844-3052, USA
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