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Mohanty S, Kumar A, Das P, Sahu SK, Mukherjee R, Ramachandranpillai R, Nair SS, Choudhuri T. Nm23-H1 induces apoptosis in primary effusion lymphoma cells via inhibition of NF-κB signaling through interaction with oncogenic latent protein vFLIP K13 of Kaposi’s sarcoma-associated herpes virus. Cell Oncol (Dordr) 2022; 45:967-989. [DOI: 10.1007/s13402-022-00701-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2022] [Indexed: 11/03/2022] Open
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SUMO Modification of Histone Demethylase KDM4A in Kaposi's Sarcoma-Associated Herpesvirus-Induced Primary Effusion Lymphoma. J Virol 2022; 96:e0075522. [PMID: 35914074 PMCID: PMC9400493 DOI: 10.1128/jvi.00755-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Primary effusion lymphoma (PEL) is a fatal B-cell lymphoma caused by Kaposi’s sarcoma-associated herpesvirus (KSHV) infection. Inducing KSHV lytic replication that causes the death of host cells is an attractive treatment approach for PE; however, combination therapy inhibiting viral production is frequently needed to improve its outcomes. We have previously shown that the KSHV lytic protein K-bZIP can SUMOylate histone lysine demethylase 4A (KDM4A) at lysine 471 (K471) and this SUMOylation is required for virus production upon KSHV reactivation. Here, we demonstrate that SUMOylation of KDM4A orchestrates PEL cell survival, a major challenge for the success of PEL treatment; and cell movement and angiogenesis, the cell functions contributing to PEL cell extravasation and dissemination. Furthermore, integrated ChIP-seq and RNA-seq analyses identified interleukin-10 (IL-10), an immunosuppressive cytokine, as a novel downstream target of KDM4A. We demonstrate that PEL-induced angiogenesis is dependent on IL-10. More importantly, single-cell RNA sequencing (scRNA-seq) analysis demonstrated that, at the late stage of KSHV reactivation, KDM4A determines the fates of PEL cells, as evidenced by two distinct cell populations; one with less apoptotic signaling expresses high levels of viral genes and the other is exactly opposite, while KDM4A-K417R-expressing cells contain only the apoptotic population with less viral gene expression. Consistently, KDM4A knockout significantly reduced cell viability and virus production in KSHV-reactivated PEL cells. Since inhibiting PEL extravasation and eradicating KSHV-infected PEL cells without increasing viral load provide a strong rationale for treating PEL, this study indicates targeting KDM4A as a promising therapeutic option for treating PEL. IMPORTANCE PEL is an aggressive and untreatable B-cell lymphoma caused by KSHV infection. Therefore, new therapeutic approaches for PEL need to be investigated. Since simultaneous induction of KSHV reactivation and apoptosis can directly kill PEL cells, they have been applied in the treatment of this hematologic malignancy and have made progress. Epigenetic therapy with histone deacetylase (HDAC) inhibitors has been proved to treat PEL. However, the antitumor efficacies of HDAC inhibitors are modest and new approaches are needed. Following our previous report showing that the histone lysine demethylase KDM4A and its SUMOylation are required for lytic reactivation of KSHV in PEL cells, we further investigated its cellular function. Here, we found that SUMOylation of KDM4A is required for the survival, movement, and angiogenesis of lytic KSHV-infected PEL cells. Together with our previous finding showing the importance of KDM4A SUMOylation in viral production, KDM4A can be a potential therapeutic target for PEL.
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Iriana S, Asha K, Repak M, Sharma-Walia N. Hedgehog Signaling: Implications in Cancers and Viral Infections. Int J Mol Sci 2021; 22:1042. [PMID: 33494284 PMCID: PMC7864517 DOI: 10.3390/ijms22031042] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/11/2021] [Accepted: 01/14/2021] [Indexed: 12/14/2022] Open
Abstract
The hedgehog (SHH) signaling pathway is primarily involved in embryonic gut development, smooth muscle differentiation, cell proliferation, adult tissue homeostasis, tissue repair following injury, and tissue polarity during the development of vertebrate and invertebrate organisms. GLIoma-associated oncogene homolog (GLI) family of zinc-finger transcription factors and smoothened (SMO) are the signal transducers of the SHH pathway. Both SHH ligand-dependent and independent mechanisms activate GLI proteins. Various transcriptional mechanisms, posttranslational modifications (phosphorylation, ubiquitination, proteolytic processing, SUMOylation, and acetylation), and nuclear-cytoplasmic shuttling control the activity of SHH signaling pathway proteins. The dysregulated SHH pathway is associated with bone and soft tissue sarcomas, GLIomas, medulloblastomas, leukemias, and tumors of breast, lung, skin, prostate, brain, gastric, and pancreas. While extensively studied in development and sarcomas, GLI family proteins play an essential role in many host-pathogen interactions, including bacterial and viral infections and their associated cancers. Viruses hijack host GLI family transcription factors and their downstream signaling cascades to enhance the viral gene transcription required for replication and pathogenesis. In this review, we discuss a distinct role(s) of GLI proteins in the process of tumorigenesis and host-pathogen interactions in the context of viral infection-associated malignancies and cancers due to other causes. Here, we emphasize the potential of the Hedgehog (HH) pathway targeting as a potential anti-cancer therapeutic approach, which in the future could also be tested in infection-associated fatalities.
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Mohanty S, Kumar A, Das P, Sahu SK, Choudhuri T. Multi-targeted therapy of everolimus in Kaposi's sarcoma associated herpes virus infected primary effusion lymphoma. Apoptosis 2018; 22:1098-1115. [PMID: 28653223 DOI: 10.1007/s10495-017-1391-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Kaposi's sarcoma associated herpes virus (KSHV) infected primary effusion lymphoma (PEL) is a rare aggressive form of non-Hodgkin's lymphoma of B cells. KSHV latent and lytic antigens modulate several host cellular signalling pathways especially mammalian target of rapamycin (mTOR), STAT-3 and nuclear factor-kappa B (NF-κB) for rapid tumor progression and immune evasion. Current chemotherapeutic strategies are becoming ineffective as they kill only dividing cells and inefficient to target molecular pathways crucial for active virus replication and its survival. In this study, we evaluated the efficacy of everolimus, an mTOR inhibitor in inducing apoptosis of PEL cells. Dose-dependent treatment of everolimus triggered mitochondria-mediated caspase-dependent apoptosis in PEL cells. Everolimus downregulated KSHV latent antigen expression with concurrent blocking of lytic reactivation for active virus replication. Everolimus also inhibited latent antigen mediated constitutively active STAT-3 and NF-κB signalling. We co-cultured everolimus treated PEL cells with immature dendritic cells and found activation of dendritic cells with increase in surface expression of CD86 and HLA-DR. As everolimus targets and disrupts KSHV antigens as well as antigen facilitated multiple signalling pathways necessary for KSHV survival and maintenance of infection with synchronised boosting of immune system against viral infection, it can be a better therapeutic approach towards treatment of PEL.
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Affiliation(s)
- Suchitra Mohanty
- Division of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Amit Kumar
- Division of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Piyanki Das
- Department of Biotechnology, Siksha Bhabana, Visva Bharati, Santiniketan, Bolpur, India
| | - Sushil Kumar Sahu
- Division of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Tathagata Choudhuri
- Department of Biotechnology, Siksha Bhabana, Visva Bharati, Santiniketan, Bolpur, India.
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Chen H, Xue L, Huang H, Wang H, Zhang X, Zhu W, Wang Z, Wang Z, Wu H. Synergistic effect of Nutlin-3 combined with MG-132 on schwannoma cells through restoration of merlin and p53 tumour suppressors. EBioMedicine 2018; 36:252-265. [PMID: 30274821 PMCID: PMC6197711 DOI: 10.1016/j.ebiom.2018.09.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/14/2018] [Accepted: 09/24/2018] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND The great majority of sporadic vestibular schwannomas (VSs) are due to the mutations of the NF2 gene encoding merlin. Sporadic VSs exhibit variable growth patterns and only a small fraction of the tumours are fast-growing; however, the underlying mechanisms remain undefined. METHODS DNA sequencing and dosage analysis were used to identify the NF2 mutation status in sporadic schwannomas. The expression and sub-cellular localization of merlin and p53-MDM2 were assessed by immunoblotting, qRT-PCR and immunofluorescence. In vitro and in vivo studies were performed to reveal the effects of Nutlin-3 (a MDM2 inhibitor) and/or MG-132(a proteasome inhibitor) on schwannomas. The proliferation of schwannoma cells was assessed by CCK-8 assay, EdU staining and Flow cytometry analysis. FINDINGS Double genetic hits of NF2 tended to occur in fast-growing tumours, characterized by the absence of merlin. The deregulation of p53-MDM2 was demonstrated to mediate merlin-deficient tumour growth, characterized by a nuclear accumulation of stabilized MDM2, contributing to a nuclear export of p53 for degradation. Nutlin-3 blocked the proliferation of schwannoma cells via a cooperative recovery of merlin and p53, accompanied by the shuttling of both proteins from the cytoplasm to the nucleus. We further demonstrated a difference in the sensitivity to Nutlin-3 between schwannoma cells with and without merlin expression. Nutlin-3 combined with MG-132 narrowed this between-group difference and triggered stronger inhibitory effects on the growth of schwannomas through coordinated reactivation of p53. INTERPRETATION These findings present treatment strategies directed on the pathogenesis of sporadic schwannomas. FUND: National Natural Science Foundation of China.
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Affiliation(s)
- Hongsai Chen
- Department of Otolaryngology Head & Neck Surgery, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China; Shanghai Institute of Precision Medicine, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lu Xue
- Department of Otolaryngology Head & Neck Surgery, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - He Huang
- Department of Otolaryngology Head & Neck Surgery, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Hantao Wang
- Department of Otolaryngology Head & Neck Surgery, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Xiaoman Zhang
- Department of Otolaryngology Head & Neck Surgery, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Weidong Zhu
- Department of Otolaryngology Head & Neck Surgery, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Zhigang Wang
- Department of Otolaryngology Head & Neck Surgery, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Zhaoyan Wang
- Department of Otolaryngology Head & Neck Surgery, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Hao Wu
- Department of Otolaryngology Head & Neck Surgery, The Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
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The regulatory role of protein phosphorylation in human gammaherpesvirus associated cancers. Virol Sin 2017; 32:357-368. [PMID: 29116588 PMCID: PMC6704201 DOI: 10.1007/s12250-017-4081-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 10/23/2017] [Indexed: 12/12/2022] Open
Abstract
Activation of specific sets of protein kinases by intracellular signal molecules
has become more and more apparent in the past decade. Phosphorylation, one of key
posttranslational modification events, is activated by kinase or regulatory protein
and is vital for controlling many physiological functions of eukaryotic cells such
as cell proliferation, differentiation, malignant transformation, and signal
transduction mediated by external stimuli. Moreovers, the reversible modification of
phosphorylation and dephosphorylation can result in different features of the target
substrate molecules including DNA binding, protein-protein interaction, subcellular
location and enzymatic activity, and is often hijacked by viral infection.
Epstein-Barr virus (EBV) and Kaposi’s sarcomaassociated herpesvirus (KSHV), two
human oncogenic gamma-herpesviruses, are shown to tightly associate with many
malignancies. In this review, we summarize the recent progresses on understanding of
molecular properties and regulatory modes of cellular and viral proteins
phosphorylation influenced by these two tumor viruses, and highlight the potential
therapeutic targets and strategies against their related cancers. ![]()
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Dai L, Lin Z, Qiao J, Chen Y, Flemington EK, Qin Z. Ribonucleotide reductase represents a novel therapeutic target in primary effusion lymphoma. Oncogene 2017; 36:5068-5074. [PMID: 28459467 PMCID: PMC5578886 DOI: 10.1038/onc.2017.122] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/16/2017] [Accepted: 03/24/2017] [Indexed: 12/15/2022]
Abstract
Primary effusion lymphoma (PEL) is a highly aggressive B-cell malignancy that is closely associated with one of oncogenic viruses infection, Kaposi's sarcoma-associated herpesvirus (KSHV). PEL prognosis is poor and patients barely survive more than 6 months even following active chemotherapy interventions. There is therefore an urgent need to discover more effective targets for PEL management. We recently found that the ribonucleotide reductase (RR) subunit M2 is potentially regulated by the key oncogenic HGF/c-MET pathway in PEL (Dai et al., Blood. 2015;126(26):2821-31). In the current study, we set to investigate the role of RR in PEL pathogenesis and to evaluate its potential as a therapeutic target. We report that the RR inhibitor 3-AP actively induces PEL cell cycle arrest through inhibiting the activity of the NF-κB pathway. Using a xenograft model, we found that 3-AP effectively suppresses PEL progression in immunodeficient mice. Transcriptome analysis of 3-AP treated PEL cell lines reveals altered cellular genes, most of whose roles in PEL have not yet been reported. Taken together, we propose that RR and its signaling pathway may serve as novel actionable targets for PEL management.
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Affiliation(s)
- L Dai
- Department of Pediatrics, East Hospital, Tongji University School of Medicine, Shanghai, China.,Research Center for Translational Medicine and Key Laboratory of Arrhythmias, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Genetics, Louisiana State University Health Sciences Center, Louisiana Cancer Research Center, New Orleans, LA, USA
| | - Z Lin
- Department of Pathology, Tulane University Health Sciences Center, Tulane Cancer Center, New Orleans, LA, USA
| | - J Qiao
- Department of Pediatrics, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Y Chen
- Research Center for Translational Medicine and Key Laboratory of Arrhythmias, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - E K Flemington
- Department of Pathology, Tulane University Health Sciences Center, Tulane Cancer Center, New Orleans, LA, USA
| | - Z Qin
- Department of Pediatrics, East Hospital, Tongji University School of Medicine, Shanghai, China.,Research Center for Translational Medicine and Key Laboratory of Arrhythmias, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Genetics, Louisiana State University Health Sciences Center, Louisiana Cancer Research Center, New Orleans, LA, USA
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Balistreri G, Viiliäinen J, Turunen M, Diaz R, Lyly L, Pekkonen P, Rantala J, Ojala K, Sarek G, Teesalu M, Denisova O, Peltonen K, Julkunen I, Varjosalo M, Kainov D, Kallioniemi O, Laiho M, Taipale J, Hautaniemi S, Ojala PM. Oncogenic Herpesvirus Utilizes Stress-Induced Cell Cycle Checkpoints for Efficient Lytic Replication. PLoS Pathog 2016; 12:e1005424. [PMID: 26891221 PMCID: PMC4758658 DOI: 10.1371/journal.ppat.1005424] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Accepted: 01/07/2016] [Indexed: 12/31/2022] Open
Abstract
Kaposi’s sarcoma herpesvirus (KSHV) causes Kaposi’s sarcoma and certain lymphoproliferative malignancies. Latent infection is established in the majority of tumor cells, whereas lytic replication is reactivated in a small fraction of cells, which is important for both virus spread and disease progression. A siRNA screen for novel regulators of KSHV reactivation identified the E3 ubiquitin ligase MDM2 as a negative regulator of viral reactivation. Depletion of MDM2, a repressor of p53, favored efficient activation of the viral lytic transcription program and viral reactivation. During lytic replication cells activated a p53 response, accumulated DNA damage and arrested at G2-phase. Depletion of p21, a p53 target gene, restored cell cycle progression and thereby impaired the virus reactivation cascade delaying the onset of virus replication induced cytopathic effect. Herpesviruses are known to reactivate in response to different kinds of stress, and our study now highlights the molecular events in the stressed host cell that KSHV has evolved to utilize to ensure efficient viral lytic replication. Herpesviruses are known to wake up and reactivate in response to different kinds of stress. Our study now highlights the key molecular host cell events that KSHV has evolved to utilize for efficient viral lytic replication: the activation of p53 and upregulation of p21, which slows down the cell cycle, but promotes viral replication and transcription of viral lytic genes. Mutations in TP53 gene are rarely found in KSHV-associated malignancies. Therefore, our work now provides a mechanistic explanation as to why the virus has evolved to retain p53.
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Affiliation(s)
- Giuseppe Balistreri
- Translational Cancer Research Program, Research Programs Unit, University of Helsinki, Helsinki, Finland
| | - Johanna Viiliäinen
- Translational Cancer Research Program, Research Programs Unit, University of Helsinki, Helsinki, Finland
| | - Mikko Turunen
- Genome-Scale Biology Program, Research Programs Unit and Department of Pathology, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Raquel Diaz
- Translational Cancer Research Program, Research Programs Unit, University of Helsinki, Helsinki, Finland
| | - Lauri Lyly
- Genome-Scale Biology Program, Research Programs Unit, University of Helsinki, Biomedicum Helsinki, Helsinki, Finland
| | - Pirita Pekkonen
- Translational Cancer Research Program, Research Programs Unit, University of Helsinki, Helsinki, Finland
| | | | - Krista Ojala
- Translational Cancer Research Program, Research Programs Unit, University of Helsinki, Helsinki, Finland
| | - Grzegorz Sarek
- Translational Cancer Research Program, Research Programs Unit, University of Helsinki, Helsinki, Finland
| | - Mari Teesalu
- Translational Cancer Research Program, Research Programs Unit, University of Helsinki, Helsinki, Finland
| | - Oxana Denisova
- Institute for Molecular Medicine (FIMM), University of Helsinki, Biomedicum Helsinki, Helsinki, Finland
| | - Karita Peltonen
- Centre for Drug Discovery, University of Helsinki, Helsinki, Finland
| | - Ilkka Julkunen
- Department of Virology, University of Turku and National Institute for Health and Welfare, Turku, Finland
| | - Markku Varjosalo
- Translational Cancer Research Program, Research Programs Unit, University of Helsinki, Helsinki, Finland
| | - Denis Kainov
- Institute for Molecular Medicine (FIMM), University of Helsinki, Biomedicum Helsinki, Helsinki, Finland
| | - Olli Kallioniemi
- Institute for Molecular Medicine (FIMM), University of Helsinki, Biomedicum Helsinki, Helsinki, Finland
| | - Marikki Laiho
- Centre for Drug Discovery, University of Helsinki, Helsinki, Finland
- Department of Radiation Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Jussi Taipale
- Genome-Scale Biology Program, Research Programs Unit and Department of Pathology, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Sampsa Hautaniemi
- Genome-Scale Biology Program, Research Programs Unit, University of Helsinki, Biomedicum Helsinki, Helsinki, Finland
| | - Päivi M. Ojala
- Translational Cancer Research Program, Research Programs Unit, University of Helsinki, Helsinki, Finland
- Foundation for the Finnish Cancer Institute, Helsinki, Finland
- Section of Virology, Division of Infectious Diseases, Department of Medicine, Imperial College London, London, United Kingdom
- * E-mail:
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Murine Gammaherpesvirus 68 LANA and SOX Homologs Counteract ATM-Driven p53 Activity during Lytic Viral Replication. J Virol 2015; 90:2571-85. [PMID: 26676792 DOI: 10.1128/jvi.02867-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/11/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Tumor suppressor p53 is activated in response to numerous cellular stresses, including viral infection. However, whether murine gammaherpesvirus 68 (MHV68) provokes p53 during the lytic replication cycle has not been extensively evaluated. Here, we demonstrate that MHV68 lytic infection induces p53 phosphorylation and stabilization in a manner that is dependent on the DNA damage response (DDR) kinase ataxia telangiectasia mutated (ATM). The induction of p53 during MHV68 infection occurred in multiple cell types, including splenocytes of infected mice. ATM and p53 activation required early viral gene expression but occurred independently of viral DNA replication. At early time points during infection, p53-responsive cellular genes were induced, coinciding with p53 stabilization and phosphorylation. However, p53-related gene expression subsided as infection progressed, even though p53 remained stable and phosphorylated. Infected cells also failed to initiate p53-dependent gene expression and undergo apoptosis in response to treatment with exogenous p53 agonists. The inhibition of p53 responses during infection required the expression of the MHV68 homologs of the shutoff and exonuclease protein (muSOX) and latency-associated nuclear antigen (mLANA). Interestingly, mLANA, but not muSOX, was necessary to prevent p53-mediated death in MHV68-infected cells under the conditions tested. This suggests that muSOX and mLANA are differentially required for inhibiting p53 in specific settings. These data reveal that DDR responses triggered by MHV68 infection promote p53 activation. However, MHV68 encodes at least two proteins capable of limiting the potential consequences of p53 function. IMPORTANCE Gammaherpesviruses are oncogenic herpesviruses that establish lifelong chronic infections. Defining how gammaherpesviruses overcome host responses to infection is important for understanding how these viruses infect and cause disease. Here, we establish that murine gammaherpesvirus 68 induces the activation of tumor suppressor p53. p53 activation was dependent on the DNA damage response kinase ataxia telangiectasia mutated. Although active early after infection, p53 became dominantly inhibited as the infection cycle progressed. Viral inhibition of p53 was mediated by the murine gammaherpesvirus 68 homologs of muSOX and mLANA. The inhibition of the p53 pathway enabled infected cells to evade p53-mediated cell death responses. These data demonstrate that a gammaherpesvirus encodes multiple proteins to limit p53-mediated responses to productive viral infection, which likely benefits acute viral replication and the establishment of chronic infection.
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Structural proteins of Kaposi's sarcoma-associated herpesvirus antagonize p53-mediated apoptosis. Oncogene 2014; 34:639-49. [PMID: 24469037 DOI: 10.1038/onc.2013.595] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 11/15/2013] [Accepted: 12/13/2013] [Indexed: 01/10/2023]
Abstract
The tumor suppressor p53 is a central regulatory molecule of apoptosis and is commonly mutated in tumors. Kaposi's sarcoma-associated herpesvirus (KSHV)-related malignancies express wild-type p53. Accordingly, KSHV encodes proteins that counteract the cell death-inducing effects of p53. Here, the effects of all KSHV genes on the p53 signaling pathway were systematically analyzed using the reversely transfected cell microarray technology. With this approach we detected eight KSHV-encoded genes with potent p53 inhibiting activity in addition to the previously described inhibitory effects of KSHV genes ORF50, K10 and K10.5. Interestingly, the three most potent newly identified inhibitors were KSHV structural proteins, namely ORF22 (glycoprotein H), ORF25 (major capsid protein) and ORF64 (tegument protein). Validation of these results with a classical transfection approach showed that these proteins inhibited p53 signaling in a dose-dependent manner and that this effect could be reversed by small interfering RNA-mediated knockdown of the respective viral gene. All three genes inhibited p53-mediated apoptosis in response to Nutlin-3 treatment in non-infected and KSHV-infected cells. Addressing putative mechanisms, we could show that these proteins could also inhibit the transactivation of the promoters of apoptotic mediators of p53 such as BAX and PIG3. Altogether, we demonstrate for the first time that structural proteins of KSHV can counteract p53-induced apoptosis. These proteins are expressed in the late lytic phase of the viral life cycle and are incorporated into the KSHV virion. Accordingly, these genes may inhibit cell death in the productive and in the early entrance phase of KSHV infection.
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11
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Association between p53 codon 72 polymorphism and sarcoma risk among Caucasians. Tumour Biol 2014; 35:4807-12. [DOI: 10.1007/s13277-014-1631-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 01/06/2014] [Indexed: 12/27/2022] Open
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Recruitment of the tumour suppressor protein p73 by Kaposi's Sarcoma Herpesvirus latent nuclear antigen contributes to the survival of primary effusion lymphoma cells. Oncogene 2012; 32:3676-85. [PMID: 22964633 DOI: 10.1038/onc.2012.385] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 06/13/2012] [Accepted: 07/13/2012] [Indexed: 01/01/2023]
Abstract
Kaposi's Sarcoma Herpesvirus (KSHV) is the causative agent of Kaposi's Sarcoma (KS) and two rare lymphoproliferative disorders, primary effusion lymphoma (PEL) and the plasmablastic variant of multicentric Castleman's disease (MCD). The KSHV latency-associated nuclear antigen-1 (LANA), required for the replication and maintenance of latent viral episomal DNA, is involved in the transcriptional regulation of viral and cellular genes and interacts with different cellular proteins, including the tumour suppressor p53. Here, we report that LANA also recruits the p53-related nuclear transcription factor p73, which influences cellular processes like DNA damage response, cell cycle progression and apoptosis. Both the full-length isoform TAp73α, as well as its dominant negative regulator ΔNp73α, interact with LANA. LANA affects TAp73α stability and sub-nuclear localisation, as well as TAp73α-mediated transcriptional activation of target genes. We observed that the small-molecule inhibitor Nutlin-3, which disrupts the interaction of p53 and p73 with MDM2, induces apoptotic cell death in p53 wild-type, as well as p53-mutant PEL cell lines, suggesting a possible involvement of p73. The small-molecule RETRA, which activates p73 in the context of mutant p53, leads to the induction of apoptosis in p53-mutant PEL cell lines. RNAi-mediated knockdown of p73 confirmed that these effects depend on the presence of the p73 protein. Furthermore, both Nutlin-3 and RETRA disrupt the LANA-p73 interaction in different PEL cell lines. These results suggest that LANA modulates p73 function and that the LANA-p73 interaction may represent a therapeutic target to interfere with the survival of latently KSHV-infected cells.
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