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Xu M, Zhang L, Feng J, Yang S, Wang Y, Wang Y, Chen M, Zhou L, Zhang J, Qin Q. Establishment and characterization of two Epstein-Barr virus-positive gastric cancer cell lines with epitheliotropic M81 strain undergoing distinct viral and altered cellular expression profiles. J Med Virol 2023; 95:e28387. [PMID: 36478267 DOI: 10.1002/jmv.28387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 11/30/2022] [Accepted: 12/03/2022] [Indexed: 12/09/2022]
Abstract
Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC) is a distinct subtype of gastric cancer (GC) distinguished by the presence of the EBV genome and limited viral gene expression within malignant epithelial cells. EBV infection is generally thought to be a relatively late event following atrophic gastritis in carcinogenesis, which implies the heterogeneity of EBVaGC. To facilitate the study of the role of EBV in EBVaGC, we established two EBV-positive GC cell lines (AGS-EBV and HGC27-EBV) with an epitheliotropic EBV strain M81 and characterized viral and cellular gene expression profiles in comparison to SNU719, a naturally derived EBV-positive GC cell line. Like SNU719, AGS-EBV and HGC27-EBV stably maintained their EBV genomes and expressed EBV-encoded small RNAs and nuclear antigen EBNA1. Comprehensive analysis of the expression of EBV-encoded miRNAs within the BamHI-A region rightward transcript region, and the transcripts of EBV latent and lytic genes in cell lines, as well as xenografts, reveals that AGS-EBV and HGC27-EBV cells undergo distinct viral expression profiles. A very small fraction of AGS-EBV and SNU719 cells can spontaneously produce infectious progeny virions, while HGC27-EBV does not. AGS-EBV (both M81 and Akata) cells largely mimic SNU719 cells in viral gene expression profiles, and altered cellular functions and pathways perturbed by EBV infection. Phylogenetic analysis of the EBV genome shows both M81 and Akata EBV strains are closely related to clinical EBVaGC isolates. Taken together, these two newly established EBV-positive GC cell lines can serve as models to further investigate the role of EBV in different contexts of gastric carcinogenesis and identify novel therapeutics against EBVaGC.
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Affiliation(s)
- Mingqian Xu
- Laboratory of Human Virology and Oncology, Shantou University Medical College, Shantou, Guangdong, China
| | - Liang Zhang
- Laboratory of Human Virology and Oncology, Shantou University Medical College, Shantou, Guangdong, China
| | - Jinfu Feng
- Laboratory of Human Virology and Oncology, Shantou University Medical College, Shantou, Guangdong, China
| | - Shuaibing Yang
- Laboratory of Human Virology and Oncology, Shantou University Medical College, Shantou, Guangdong, China
| | - Yixuan Wang
- Laboratory of Human Virology and Oncology, Shantou University Medical College, Shantou, Guangdong, China
| | - Yuyi Wang
- Laboratory of Human Virology and Oncology, Shantou University Medical College, Shantou, Guangdong, China
| | - Meiyang Chen
- Laboratory of Human Virology and Oncology, Shantou University Medical College, Shantou, Guangdong, China
| | - Li Zhou
- Department of Gynecologic Oncology, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Junjie Zhang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, State Key Laboratory of Virology, Medical Research Institute, Wuhan University, Wuhan, Hubei, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, Hubei, China
| | - Qingsong Qin
- Laboratory of Human Virology and Oncology, Shantou University Medical College, Shantou, Guangdong, China
- Guangdong Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou, Guangdong, China
- Guangdong Provincial Key Laboratory for Diagnosis and Treatment of Breast Cancer, Shantou University Medical College, Shantou, Guangdong, China
- Center of Pathogen Biology and Immunology, Institute of Basic Medical Research, Shantou University Medical College, Shantou, Guangdong, China
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Van Sciver N, Ohashi M, Nawandar DM, Pauly NP, Lee D, Makielski KR, Bristol JA, Tsao SW, Lambert PF, Johannsen EC, Kenney SC. ΔNp63α promotes Epstein-Barr virus latency in undifferentiated epithelial cells. PLoS Pathog 2021; 17:e1010045. [PMID: 34748616 PMCID: PMC8601603 DOI: 10.1371/journal.ppat.1010045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/18/2021] [Accepted: 10/18/2021] [Indexed: 01/27/2023] Open
Abstract
Epstein-Barr virus (EBV) is a human herpesvirus that causes infectious mononucleosis and contributes to both B-cell and epithelial-cell malignancies. EBV-infected epithelial cell tumors, including nasopharyngeal carcinoma (NPC), are largely composed of latently infected cells, but the mechanism(s) maintaining viral latency are poorly understood. Expression of the EBV BZLF1 (Z) and BRLF1 (R) encoded immediate-early (IE) proteins induces lytic infection, and these IE proteins activate each other's promoters. ΔNp63α (a p53 family member) is required for proliferation and survival of basal epithelial cells and is over-expressed in NPC tumors. Here we show that ΔNp63α promotes EBV latency by inhibiting activation of the BZLF1 IE promoter (Zp). Furthermore, we find that another p63 gene splice variant, TAp63α, which is expressed in some Burkitt and diffuse large B cell lymphomas, also represses EBV lytic reactivation. We demonstrate that ΔNp63α inhibits the Z promoter indirectly by preventing the ability of other transcription factors, including the viral IE R protein and the cellular KLF4 protein, to activate Zp. Mechanistically, we show that ΔNp63α promotes viral latency in undifferentiated epithelial cells both by enhancing expression of a known Zp repressor protein, c-myc, and by decreasing cellular p38 kinase activity. Furthermore, we find that the ability of cis-platinum chemotherapy to degrade ΔNp63α contributes to the lytic-inducing effect of this agent in EBV-infected epithelial cells. Together these findings demonstrate that the loss of ΔNp63α expression, in conjunction with enhanced expression of differentiation-dependent transcription factors such as BLIMP1 and KLF4, induces lytic EBV reactivation during normal epithelial cell differentiation. Conversely, expression of ΔNp63α in undifferentiated nasopharyngeal carcinoma cells and TAp63α in Burkitt lymphoma promotes EBV latency in these malignancies.
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Affiliation(s)
- Nicholas Van Sciver
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
| | - Makoto Ohashi
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
| | - Dhananjay M. Nawandar
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
- Currently at Ring Therapeutics, Cambridge, Massachusetts, United States of America
| | - Nicholas P. Pauly
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
| | - Denis Lee
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
| | - Kathleen R. Makielski
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
| | - Jillian A. Bristol
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
| | - Sai Wah Tsao
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Paul F. Lambert
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
| | - Eric C. Johannsen
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Shannon C. Kenney
- Department of Oncology, School of Medicine and Public Health, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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Li H, Li Y, Hu J, Liu S, Luo X, Tang M, Bode AM, Dong Z, Liu X, Liao W, Cao Y. (-)-Epigallocatechin-3-gallate inhibits EBV lytic replication via targeting LMP1-mediated MAPK signal axes. Oncol Res 2021; 28:763-778. [PMID: 33629943 PMCID: PMC8420900 DOI: 10.3727/096504021x16135618512563] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Epstein–Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) plays an important oncogenic role in the viral latent infection. Recently, increasing evidence indicates that the high expression of LMP1 during EBV lytic cycle is related to the viral lytic replication. However, the mechanism by which LMP1 regulates EBV lytic replication remains unclear. (−)-Epigallocatechin-3-gallate (EGCG) prevents carcinogenesis by directly targeting numerous membrane proteins and effectively inhibits EBV lytic cascade. Here, we demonstrated that LMP1 promotes EBV lytic replication through the downstream signal molecules MAPKs, including ERKs, p38, and JNKs. LMP1 induces the phosphorylation of p53 through MAPKs to enhance the ability of wild-type p53 (wt-p53) to activate expression of BZLF1 gene, while the JNKs/c-Jun signal axis appears to be involved in EBV lytic replication induced by LMP1 in p53 mutant manner. We provided the first evidence that EGCG directly targets the viral membrane LMP1 (Kd = 0.36 μM, n = 1) using fluorescence quenching, isothermal titration calorimetry (ITC) assay, and CNBR-activated Sepharose 4B pull-down affinity chromatography. Furthermore, we revealed that EGCG inhibits EBV lytic replication via suppressing LMP1 and thus blocking the downstream MAPKs/wt-p53 signal axis in AGS-EBV cells and JNKs/c-Jun signal axis in p53 mutant B95.8 cells. Our study, for the first time, reports the binding and inhibitory efficacy of EGCG to the LMP1, which is a key oncoprotein encoded by EBV. These findings suggest the novel function of LMP1 in the regulation of EBV lytic cycle and reveal the new role of EGCG in EBV-associated malignancies through suppressing viral reactivation.
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Affiliation(s)
- Hongde Li
- Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, China.,Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, China
| | - Yueshuo Li
- Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, China.,Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, Changsha, China
| | - Jianmin Hu
- Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, China.,Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, Changsha, China
| | - Sufang Liu
- Division of Hematology, Institute of Molecular Hematology, the Second Xiangya 13 Hospital, Central South University at Changsha, China
| | - Xiangjian Luo
- Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, China.,Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, Changsha, China.,The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Min Tang
- Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, China.,Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, Changsha, China
| | - Ann M Bode
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Zigang Dong
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA.,College of Medicine, Zhengzhou University, Zhengzhou, China
| | - Xinqi Liu
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University at Tianjin, China
| | - Weihua Liao
- Department of Radiology, Xiangya Hospital, Central South University at Changsha, China
| | - Ya Cao
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, Changsha, China.,Molecular Imaging Research Center of Central South University, Changsha, China.,Research Center for Technologies of Nucleic Acid Based Diagnostics and Therapeutics, Hunan Province, Changsha, China.,National Joint Engineering Research Center for Genetic Diagnostics of Infectious Diseases and Cancer, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, Changsha, China
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Kraus RJ, Cordes BLA, Sathiamoorthi S, Patel P, Yuan X, Iempridee T, Yu X, Lee DL, Lambert PF, Mertz JE. Reactivation of Epstein-Barr Virus by HIF-1α Requires p53. J Virol 2020; 94:e00722-20. [PMID: 32641480 PMCID: PMC7459560 DOI: 10.1128/jvi.00722-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/29/2020] [Indexed: 12/14/2022] Open
Abstract
We previously reported that the cellular transcription factor hypoxia-inducible factor 1α (HIF-1α) binds a hypoxia response element (HRE) located within the promoter of Epstein-Barr virus's (EBV's) latent-lytic switch BZLF1 gene, Zp, inducing viral reactivation. In this study, EBV-infected cell lines derived from gastric cancers and Burkitt lymphomas were incubated with HIF-1α-stabilizing drugs: the iron chelator deferoxamine (Desferal [DFO]), a neddylation inhibitor (pevonedistat [MLN-4924]), and a prolyl hydroxylase inhibitor (roxadustat [FG-4592]). DFO and MLN-4924, but not FG-4592, induced accumulation of both lytic EBV proteins and phosphorylated p53 in cell lines that contain a wild-type p53 gene. FG-4592 also failed to activate transcription from Zp in a reporter assay despite inducing accumulation of HIF-1α and transcription from another HRE-containing promoter. Unexpectedly, DFO failed to induce EBV reactivation in cell lines that express mutant or no p53 or when p53 expression was knocked down with short hairpin RNAs (shRNAs). Likewise, HIF-1α failed to activate transcription from Zp when p53 was knocked out by CRISPR-Cas9. Importantly, DFO induced binding of p53 as well as HIF-1α to Zp in chromatin immunoprecipitation (ChIP) assays, but only when the HRE was present. Nutlin-3, a drug known to induce accumulation of phosphorylated p53, synergized with DFO and MLN-4924 in inducing EBV reactivation. Conversely, KU-55933, a drug that inhibits ataxia telangiectasia mutated, thereby preventing p53 phosphorylation, inhibited DFO-induced EBV reactivation. Lastly, activation of Zp transcription by DFO and MLN-4924 mapped to its HRE. Thus, we conclude that induction of BZLF1 gene expression by HIF-1α requires phosphorylated, wild-type p53 as a coactivator, with HIF-1α binding recruiting p53 to Zp.IMPORTANCE EBV, a human herpesvirus, is latently present in most nasopharyngeal carcinomas, Burkitt lymphomas, and some gastric cancers. To develop a lytic-induction therapy for treating patients with EBV-associated cancers, we need a way to efficiently reactivate EBV into lytic replication. EBV's BZLF1 gene product, Zta, usually controls this reactivation switch. We previously showed that HIF-1α binds the BZLF1 gene promoter, inducing Zta synthesis, and HIF-1α-stabilizing drugs can induce EBV reactivation. In this study, we determined which EBV-positive cell lines are reactivated by classes of HIF-1α-stabilizing drugs. We found, unexpectedly, that HIF-1α-stabilizing drugs only induce reactivation when they also induce accumulation of phosphorylated, wild-type p53. Fortunately, p53 phosphorylation can also be provided by drugs such as nutlin-3, leading to synergistic reactivation of EBV. These findings indicate that some HIF-1α-stabilizing drugs may be helpful as part of a lytic-induction therapy for treating patients with EBV-positive malignancies that contain wild-type p53.
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MESH Headings
- Cell Line, Tumor
- Cyclopentanes/pharmacology
- Deferoxamine/pharmacology
- Enzyme Inhibitors/pharmacology
- Epithelial Cells/drug effects
- Epithelial Cells/metabolism
- Epithelial Cells/virology
- Gene Expression Regulation
- Glycine/analogs & derivatives
- Glycine/pharmacology
- Herpesvirus 4, Human/drug effects
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/growth & development
- Herpesvirus 4, Human/metabolism
- Host-Pathogen Interactions/drug effects
- Host-Pathogen Interactions/genetics
- Humans
- Hypoxia-Inducible Factor 1, alpha Subunit/agonists
- Hypoxia-Inducible Factor 1, alpha Subunit/genetics
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Imidazoles/pharmacology
- Iron Chelating Agents/pharmacology
- Isoquinolines/pharmacology
- Lymphocytes/drug effects
- Lymphocytes/metabolism
- Lymphocytes/virology
- Morpholines/pharmacology
- Piperazines/pharmacology
- Prolyl-Hydroxylase Inhibitors/pharmacology
- Promoter Regions, Genetic
- Protein Binding/drug effects
- Pyrimidines/pharmacology
- Pyrones/pharmacology
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Response Elements
- Signal Transduction
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Tumor Suppressor Protein p53/antagonists & inhibitors
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
- Virus Activation/drug effects
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Affiliation(s)
- Richard J Kraus
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Blue-Leaf A Cordes
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Saraniya Sathiamoorthi
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Parita Patel
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Xueying Yuan
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Tawin Iempridee
- National Nanotechnology Center, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Xianming Yu
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Denis L Lee
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Paul F Lambert
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Janet E Mertz
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
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Wang M, Wu W, Zhang Y, Yao G, Gu B. Rapamycin enhances lytic replication of Epstein-Barr virus in gastric carcinoma cells by increasing the transcriptional activities of immediate-early lytic promoters. Virus Res 2018; 244:173-180. [PMID: 29169830 DOI: 10.1016/j.virusres.2017.11.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 11/18/2017] [Accepted: 11/18/2017] [Indexed: 12/12/2022]
Abstract
Epstein-Barr virus (EBV), a human herpesvirus, is linked to both epithelial and lymphoid malignancies. Induction of EBV reactivation is a potential therapeutic strategy for EBV-associated tumors. In this study, we assessed the effects of rapamycin on EBV reactivation in gastric carcinoma cells. We found that rapamycin upregulated expression of EBV lytic proteins and increased the viral proliferation triggered by the EBV lytic inducer sodium butyrate. Reverse transcription-qPCR, luciferase activity assays, chromatin immunoprecipitation and western blotting were employed to explore the mechanism by which rapamycin promotes EBV reactivation. Our results showed that rapamycin treatment resulted in increased mRNA levels of EBV immediate-early genes. Rapamycin also enhanced the transcriptional activities of the EBV immediate-early lytic promoters Zp and Rp by strengthening Sp1 binding. Repression of the cellular ataxia telangiectasia-mutated/p53 pathway by siRNA-mediated knockdown of the ataxia telangiectasia-mutated gene significantly abrogated virus reactivation by rapamycin/sodium butyrate treatment, indicating that the ataxia telangiectasia-mutated/p53 pathway is involved in rapamycin-promoted EBV reactivation. Taken together, these findings demonstrate that rapamycin might have the potential to enhance the effectiveness of oncolytic viral therapies developed for EBV-associated malignancies.
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MESH Headings
- Ataxia Telangiectasia Mutated Proteins/antagonists & inhibitors
- Ataxia Telangiectasia Mutated Proteins/genetics
- Ataxia Telangiectasia Mutated Proteins/metabolism
- Butyric Acid/pharmacology
- Cell Line, Tumor
- Cell Survival/drug effects
- DNA, Viral/genetics
- DNA, Viral/metabolism
- Gastric Mucosa/drug effects
- Gastric Mucosa/metabolism
- Gastric Mucosa/virology
- Gene Expression Regulation
- Genes, Reporter
- Herpesvirus 4, Human/drug effects
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/growth & development
- Herpesvirus 4, Human/metabolism
- Humans
- Immediate-Early Proteins/agonists
- Immediate-Early Proteins/genetics
- Immediate-Early Proteins/metabolism
- Luciferases/genetics
- Luciferases/metabolism
- Oncolytic Virotherapy/methods
- Promoter Regions, Genetic/drug effects
- Protein Binding
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Sirolimus/pharmacology
- Sp1 Transcription Factor/genetics
- Sp1 Transcription Factor/metabolism
- Transcription, Genetic
- Tumor Suppressor Protein p53/antagonists & inhibitors
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
- Virus Activation/drug effects
- Virus Replication/drug effects
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Affiliation(s)
- Man Wang
- Institute for Translational Medicine, Medical College of Qingdao University, Qingdao, 266021, China.
| | - Wei Wu
- Institute for Translational Medicine, Medical College of Qingdao University, Qingdao, 266021, China
| | - Yinfeng Zhang
- Institute for Translational Medicine, Medical College of Qingdao University, Qingdao, 266021, China
| | - Guoliang Yao
- Department of General Surgery, The First Affiliated Hospital of Henan University of Science and Technology, Luoyang, 471003, China
| | - Bianli Gu
- Henan Key Laboratory of Cancer Epigenetics, Cancer Hospital, The First Affiliated Hospital, College of Clinical Medicine, Medical College of Henan University of Science and Technology, Luoyang, 471003, China
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Hau PM, Tsao SW. Epstein-Barr Virus Hijacks DNA Damage Response Transducers to Orchestrate Its Life Cycle. Viruses 2017; 9:v9110341. [PMID: 29144413 PMCID: PMC5707548 DOI: 10.3390/v9110341] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/30/2017] [Accepted: 11/08/2017] [Indexed: 12/12/2022] Open
Abstract
The Epstein–Barr virus (EBV) is a ubiquitous virus that infects most of the human population. EBV infection is associated with multiple human cancers, including Burkitt’s lymphoma, Hodgkin’s lymphoma, a subset of gastric carcinomas, and almost all undifferentiated non-keratinizing nasopharyngeal carcinoma. Intensive research has shown that EBV triggers a DNA damage response (DDR) during primary infection and lytic reactivation. The EBV-encoded viral proteins have been implicated in deregulating the DDR signaling pathways. The consequences of DDR inactivation lead to genomic instability and promote cellular transformation. This review summarizes the current understanding of the relationship between EBV infection and the DDR transducers, including ATM (ataxia telangiectasia mutated), ATR (ATM and Rad3-related), and DNA-PK (DNA-dependent protein kinase), and discusses how EBV manipulates the DDR signaling pathways to complete the replication process of viral DNA during lytic reactivation.
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Affiliation(s)
- Pok Man Hau
- Department of Anatomical and Cellular Pathology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
| | - Sai Wah Tsao
- School of Biomedical Science, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
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7
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Tikhmyanova N, Tutton S, Martin KA, Lu F, Kossenkov AV, Paparoidamis N, Kenney S, Salvino JM, Lieberman PM. Small molecule perturbation of the CAND1-Cullin1-ubiquitin cycle stabilizes p53 and triggers Epstein-Barr virus reactivation. PLoS Pathog 2017; 13:e1006517. [PMID: 28715492 DOI: 10.1371/journal.ppat.1006517] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 07/27/2017] [Accepted: 07/06/2017] [Indexed: 12/13/2022] Open
Abstract
The chemical probe C60 efficiently triggers Epstein-Barr Virus (EBV) reactivation from latency through an unknown mechanism. Here, we identify the Cullin exchange factor CAND1 as a biochemical target of C60. We also identified CAND1 in an shRNA library screen for EBV lytic reactivation. Gene expression profiling revealed that C60 activates the p53 pathway and protein analysis revealed a strong stabilization and S15 phosphorylation of p53. C60 reduced Cullin1 association with CAND1 and led to a global accumulation of ubiquitylated substrates. C60 also stabilized the EBV immediate early protein ZTA through a Cullin-CAND1-interaction motif in the ZTA transcription activation domain. We propose that C60 perturbs the normal interaction and function of CAND1 with Cullins to promote the stabilization of substrates like ZTA and p53, leading to EBV reactivation from latency. Understanding the mechanism of action of C60 may provide new approaches for treatment of EBV associated tumors, as well as new tools to stabilize p53.
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8
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Wu CC, Fang CY, Cheng YJ, Hsu HY, Chou SP, Huang SY, Tsai CH, Chen JY. Inhibition of Epstein-Barr virus reactivation by the flavonoid apigenin. J Biomed Sci 2017; 24:2. [PMID: 28056971 PMCID: PMC5217310 DOI: 10.1186/s12929-016-0313-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 12/18/2016] [Indexed: 12/03/2022] Open
Abstract
Background Lytic reactivation of EBV has been reported to play an important role in human diseases, including NPC carcinogenesis. Inhibition of EBV reactivation is considered to be of great benefit in the treatment of virus-associated diseases. For this purpose, we screened for inhibitory compounds and found that apigenin, a flavonoid, seemed to have the ability to inhibit EBV reactivation. Methods We performed western blotting, immunofluorescence and luciferase analyses to determine whether apigenin has anti-EBV activity. Results Apigenin inhibited expression of the EBV lytic proteins, Zta, Rta, EAD and DNase in epithelial and B cells. It also reduced the number of EBV-reactivating cells detectable by immunofluorescence analysis. In addition, apigenin has been found to reduce dramatically the production of EBV virions. Luciferase reporter analysis was performed to determine the mechanism by which apigenin inhibits EBV reactivation: apigenin suppressed the activity of the immediate-early (IE) gene Zta and Rta promoters, suggesting it can block initiation of the EBV lytic cycle. Conclusion Taken together, apigenin inhibits EBV reactivation by suppressing the promoter activities of two viral IE genes, suggesting apigenin is a potential dietary compound for prevention of EBV reactivation. Electronic supplementary material The online version of this article (doi:10.1186/s12929-016-0313-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chung-Chun Wu
- National Institute of Cancer Research, National Health Research Institutes, No.35, Keyan Road, Zhunan Miaoli, Miaoli County, Taiwan.
| | - Chih-Yeu Fang
- National Institute of Cancer Research, National Health Research Institutes, No.35, Keyan Road, Zhunan Miaoli, Miaoli County, Taiwan.,Department of Pathology, Wan Fang Hospital, Taipei Medical University, Taipei, 116, Taiwan
| | - Yu-Jhen Cheng
- National Institute of Cancer Research, National Health Research Institutes, No.35, Keyan Road, Zhunan Miaoli, Miaoli County, Taiwan
| | - Hui-Yu Hsu
- National Institute of Cancer Research, National Health Research Institutes, No.35, Keyan Road, Zhunan Miaoli, Miaoli County, Taiwan
| | - Sheng-Ping Chou
- National Institute of Cancer Research, National Health Research Institutes, No.35, Keyan Road, Zhunan Miaoli, Miaoli County, Taiwan
| | - Sheng-Yen Huang
- National Institute of Cancer Research, National Health Research Institutes, No.35, Keyan Road, Zhunan Miaoli, Miaoli County, Taiwan
| | - Ching-Hwa Tsai
- Department of Microbiology, College of Medicine National Health Research Institutes, National Taiwan University, No.35, Keyan Road, Zhunan Town, Miaoli County, Taipei, Taiwan
| | - Jen-Yang Chen
- National Institute of Cancer Research, National Health Research Institutes, No.35, Keyan Road, Zhunan Miaoli, Miaoli County, Taiwan. .,Department of Microbiology, College of Medicine National Health Research Institutes, National Taiwan University, No.35, Keyan Road, Zhunan Town, Miaoli County, Taipei, Taiwan.
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Hau PM, Deng W, Jia L, Yang J, Tsurumi T, Chiang AKS, Huen MSY, Tsao SW. Role of ATM in the formation of the replication compartment during lytic replication of Epstein-Barr virus in nasopharyngeal epithelial cells. J Virol 2015; 89:652-68. [PMID: 25355892 PMCID: PMC4301132 DOI: 10.1128/jvi.01437-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 10/10/2014] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED Epstein-Barr virus (EBV), a type of oncogenic herpesvirus, is associated with human malignancies. Previous studies have shown that lytic reactivation of EBV in latently infected cells induces an ATM-dependent DNA damage response (DDR). The involvement of ATM activation has been implicated in inducing viral lytic gene transcription to promote lytic reactivation. Its contribution to the formation of a replication compartment during lytic reactivation of EBV remains poorly defined. In this study, the role of ATM in viral DNA replication was investigated in EBV-infected nasopharyngeal epithelial cells. We observed that induction of lytic infection of EBV triggers ATM activation and localization of DDR proteins at the viral replication compartments. Suppression of ATM activity using a small interfering RNA (siRNA) approach or a specific chemical inhibitor profoundly suppressed replication of EBV DNA and production of infectious virions in EBV-infected cells induced to undergo lytic reactivation. We further showed that phosphorylation of Sp1 at the serine-101 residue is essential in promoting the accretion of EBV replication proteins at the replication compartment, which is crucial for replication of viral DNA. Knockdown of Sp1 expression by siRNA effectively suppressed the replication of viral DNA and localization of EBV replication proteins to the replication compartments. Our study supports an important role of ATM activation in lytic reactivation of EBV in epithelial cells, and phosphorylation of Sp1 is an essential process downstream of ATM activation involved in the formation of viral replication compartments. Our study revealed an essential role of the ATM-dependent DDR pathway in lytic reactivation of EBV, suggesting a potential antiviral replication strategy using specific DDR inhibitors. IMPORTANCE Epstein-Barr virus (EBV) is closely associated with human malignancies, including undifferentiated nasopharyngeal carcinoma (NPC), which has a high prevalence in southern China. EBV can establish either latent or lytic infection depending on the cellular context of infected host cells. Recent studies have highlighted the importance of the DNA damage response (DDR), a surveillance mechanism that evolves to maintain genome integrity, in regulating lytic EBV replication. However, the underlying molecular events are largely undefined. ATM is consistently activated in EBV-infected epithelial cells when they are induced to undergo lytic reactivation. Suppression of ATM inhibits replication of viral DNA. Furthermore, we observed that phosphorylation of Sp1 at the serine-101 residue, a downstream event of ATM activation, plays an essential role in the formation of viral replication compartments for replication of virus DNA. Our study provides new insights into the mechanism through which EBV utilizes the host cell machinery to promote replication of viral DNA upon lytic reactivation.
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Affiliation(s)
- Pok Man Hau
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Wen Deng
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Lin Jia
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Jie Yang
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Tatsuya Tsurumi
- Division of Virology, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Alan Kwok Shing Chiang
- Department of Pediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Michael Shing-Yan Huen
- Genome Stability Research Laboratory, Department of Anatomy and Centre for Cancer Research, The University of Hong Kong, Hong Kong SAR
| | - Sai Wah Tsao
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
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10
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Gorres KL, Daigle D, Mohanram S, Miller G. Activation and repression of Epstein-Barr Virus and Kaposi's sarcoma-associated herpesvirus lytic cycles by short- and medium-chain fatty acids. J Virol 2014; 88:8028-44. [PMID: 24807711 DOI: 10.1128/JVI.00722-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The lytic cycles of Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are induced in cell culture by sodium butyrate (NaB), a short-chain fatty acid (SCFA) histone deacetylase (HDAC) inhibitor. Valproic acid (VPA), another SCFA and an HDAC inhibitor, induces the lytic cycle of KSHV but blocks EBV lytic reactivation. To explore the hypothesis that structural differences between NaB and VPA account for their functional effects on the two related viruses, we investigated the capacity of 16 structurally related short- and medium-chain fatty acids to promote or prevent lytic cycle reactivation. SCFAs differentially affected EBV and KSHV reactivation. KSHV was reactivated by all SCFAs that are HDAC inhibitors, including phenylbutyrate. However, several fatty acid HDAC inhibitors, such as isobutyrate and phenylbutyrate, did not reactivate EBV. Reactivation of KSHV lytic transcripts could not be blocked completely by any fatty acid tested. In contrast, several medium-chain fatty acids inhibited lytic activation of EBV. Fatty acids that blocked EBV reactivation were more lipophilic than those that activated EBV. VPA blocked activation of the BZLF1 promoter by NaB but did not block the transcriptional function of ZEBRA. VPA also blocked activation of the DNA damage response that accompanies EBV lytic cycle activation. Properties of SCFAs in addition to their effects on chromatin are likely to explain activation or repression of EBV. We concluded that fatty acids stimulate the two related human gammaherpesviruses to enter the lytic cycle through different pathways. Importance: Lytic reactivation of EBV and KSHV is needed for persistence of these viruses and plays a role in carcinogenesis. Our direct comparison highlights the mechanistic differences in lytic reactivation between related human oncogenic gammaherpesviruses. Our findings have therapeutic implications, as fatty acids are found in the diet and produced by the human microbiota. Small-molecule inducers of the lytic cycle are desired for oncolytic therapy. Inhibition of viral reactivation, alternatively, may prove useful in cancer treatment. Overall, our findings contribute to the understanding of pathways that control the latent-to-lytic switch and identify naturally occurring molecules that may regulate this process.
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11
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Huang SY, Fang CY, Wu CC, Tsai CH, Lin SF, Chen JY. Reactive oxygen species mediate Epstein-Barr virus reactivation by N-methyl-N'-nitro-N-nitrosoguanidine. PLoS One 2013; 8:e84919. [PMID: 24376853 PMCID: PMC3869928 DOI: 10.1371/journal.pone.0084919] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 11/20/2013] [Indexed: 12/15/2022] Open
Abstract
N-nitroso compounds (NOCs) and Epstein-Barr virus (EBV) reactivation have been suggested to play a role in the development of nasopharyngeal carcinoma (NPC). Although chemicals have been shown to be a risk factor contributing to the carcinogenesis of NPC, the underlying mechanism is not fully understood. We demonstrated recently that N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) enhances the genomic instability and tumorigenicity of NPC cells via induction of EBV reactivation. However, the mechanisms that trigger EBV reactivation from latency remain unclear. Here, we address the role of ROS in induction of EBV reactivation under MNNG treatment. EBV reactivation was induced in over 70% of EBV-positive NA cells and the promoter of Rta (Rp) was activated after MNNG treatment. Inhibitor experiments revealed ATM, p38 MAPK and JNK were activated by ROS and involved in MNNG-induced EBV reactivation. Significantly, ROS scavengers N-acetyl-L-cysteine (NAC), catalase and reduced glutathione inhibited EBV reactivation under MNNG and H₂O₂ treatment, suggesting ROS mediate EBV reactivation. The p53 was essential for EBV reactivation and the Rp activation by MNNG. Moreover, the p53 was phosphorylated, translocated into nucleus, and bound to Rp following ROS stimulation. The results suggest ROS play an important role in initiation of EBV reactivation by MNNG through a p53-dependent mechanism. Our findings demonstrate novel signaling mechanisms used by NOCs to induce EBV reactivation and provide a novel insight into NOCs link the EBV reactivation in the contribution to the development of NPC. Notably, this study indicates that antioxidants might be effective for inhibiting N-nitroso compound-induced EBV reactivation and therefore could be promising preventive and therapeutic agents for EBV reactivation-associated malignancies.
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Affiliation(s)
- Sheng-Yen Huang
- Graduate Program of Biotechnology in Medicine of National Tsing Hua University and National Health Research Institutes, Hsinchu, Taiwan
- Institute of Biotechnology, Department of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan
- National Institute of Cancer Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Chih-Yeu Fang
- National Institute of Cancer Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Chung-Chun Wu
- National Institute of Cancer Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Ching-Hwa Tsai
- Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Su-Fang Lin
- National Institute of Cancer Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Jen-Yang Chen
- Graduate Program of Biotechnology in Medicine of National Tsing Hua University and National Health Research Institutes, Hsinchu, Taiwan
- Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
- National Institute of Cancer Research, National Health Research Institutes, Miaoli County, Taiwan
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12
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Zou H, Jiang Z, Li R, Jia Y, Yang X, Ni Y, Zhao R. p53 cooperates with Sp1 to regulate breed-dependent expression of glucocorticoid receptor in the liver of preweaning piglets. PLoS One 2013; 8:e70494. [PMID: 23950944 PMCID: PMC3737268 DOI: 10.1371/journal.pone.0070494] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 06/20/2013] [Indexed: 12/19/2022] Open
Abstract
Previous studies indicate that Chinese indigenous pig breeds demonstrate distinct pattern of glucocorticoid receptor (GR) expression, which is associated with their unique growth and metabolic phenotypes. Here we sought to unravel the transcriptional mechanisms underlying the breed-specific hepatic GR expression in preweaning Chinese Erhualian (EHL) and Western Large White (LW) piglets. Total GR mRNA and the predominant GR mRNA variant 1-9/10 were expressed significantly higher in EHL compared with LW piglets (P<0.01), which was associated with more enriched histone H3 acetylation on 1-9/10 promoter (P<0.05). Nuclear content of transcription factor specificity protein 1 (Sp1) was significantly lower in EHL piglets, yet its binding to GR 1-9/10 promoter was significantly higher in EHL piglets, as revealed by chromatin immunoprecipitation assays. Although p53 binding to GR promoter 1-9/10 did not differ between breeds, expression of p53 mRNA and protein, as well as its binding to Sp1, were significantly higher in EHL piglets. Moreover, p53 activator doxorubicin significantly enhanced GR 1-9/10 promoter activity in HepG2 cells at 100 nM, which was associated with significantly higher protein content of p53 and GR. Sp1 inhibitor, mithramycin A, significantly inhibited (P<0.05) the basal activity of GR promoter 1-9/10 and completely blocked doxorubicin -induced activation of GR promoter 1-9/10. These data indicate that higher hepatic GR expression in EHL piglets attributes mainly to the enhanced transcription of GR promoter 1-9/10, which is achieved from breed-specific interaction of p53 and Sp1 on porcine GR 1-9/10 promoter.
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Affiliation(s)
- Huafeng Zou
- Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, P. R. China
| | - Zheng Jiang
- Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, P. R. China
| | - Runsheng Li
- Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, P. R. China
| | - Yimin Jia
- Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, P. R. China
| | - Xiaojing Yang
- Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, P. R. China
| | - Yingdong Ni
- Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, P. R. China
| | - Ruqian Zhao
- Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, P. R. China
- * E-mail:
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Hagemeier SR, Barlow EA, Meng Q, Kenney SC. The cellular ataxia telangiectasia-mutated kinase promotes epstein-barr virus lytic reactivation in response to multiple different types of lytic reactivation-inducing stimuli. J Virol 2012; 86:13360-70. [PMID: 23015717 PMCID: PMC3503132 DOI: 10.1128/jvi.01850-12] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 09/20/2012] [Indexed: 12/22/2022] Open
Abstract
The Epstein-Barr virus (EBV) latent-to-lytic switch is mediated by the viral proteins BZLF1 (Z), BRLF1 (R), and BRRF1 (Na). Since we previously showed that DNA-damaging agents (including chemotherapy and irradiation) can induce EBV lytic reactivation and recently demonstrated that wild-type p53 contributes to lytic reactivation, we investigated the role of the ATM kinase during EBV reactivation. ATM phosphorylates and activates p53, as well as numerous other substrates involved in the cellular DNA damage response. Using an ATM inhibitor (KU55933), we found that ATM activity is required for efficient induction of EBV lytic gene expression by a variety of different stimuli, including a histone deacetylase (HDAC) inhibitor, the transforming growth factor β (TGF-β) cytokine, a demethylating agent (5-azacytidine), B cell receptor engagement with anti-IgG antibody, hydrogen peroxide, and the proteosome inhibitor bortezomib. In EBV-infected AGS (gastric) cells, knockdown of ATM, or p53, expression inhibits EBV reactivation. Conversely, treatment of these cells with nutlin-3 (which activates p53 and ATM) robustly induces lytic reactivation in a p53- and ATM-dependent manner. The ability of the EBV R and Na proteins to induce lytic reactivation in EBV-infected AGS cells is ATM dependent. However, overexpression of Z induces lytic gene expression in the presence or absence of ATM activity. Our results suggest that ATM enhances Z promoter activity in the context of the intact EBV genome and that p53 contributes to the ATM effect. Nevertheless, since we found that ATM inhibitors also reduce lytic reactivation in Burkitt lymphoma cells that have no p53, additional ATM substrates must also contribute to the ATM effect.
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Affiliation(s)
| | | | - Qiao Meng
- McArdle Laboratory for Cancer Research, Department of Oncology
| | - Shannon C. Kenney
- McArdle Laboratory for Cancer Research, Department of Oncology
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
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