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Luan Y, Long W, Dai L, Tao P, Deng Z, Xia Z. Linear ubiquitination regulates the KSHV replication and transcription activator protein to control infection. Nat Commun 2024; 15:5515. [PMID: 38951495 PMCID: PMC11217414 DOI: 10.1038/s41467-024-49887-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 06/21/2024] [Indexed: 07/03/2024] Open
Abstract
Like many other viruses, KSHV has two life cycle modes: the latent phase and the lytic phase. The RTA protein from KSHV is essential for lytic reactivation, but how this protein's activity is regulated is not fully understood. Here, we report that linear ubiquitination regulates the activity of RTA during KSHV lytic reactivation and de novo infection. Overexpressing OTULIN inhibits KSHV lytic reactivation, whereas knocking down OTULIN or overexpressing HOIP enhances it. Intriguingly, we found that RTA is linearly polyubiquitinated by HOIP at K516 and K518, and these modifications control the RTA's nuclear localization. OTULIN removes linear polyubiquitin chains from cytoplasmic RTA, preventing its nuclear import. The RTA orthologs encoded by the EB and MHV68 viruses are also linearly polyubiquitinated and regulated by OTULIN. Our study establishes that linear polyubiquitination plays a critically regulatory role in herpesvirus infection, adding virus infection to the list of biological processes known to be controlled by linear polyubiquitination.
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Affiliation(s)
- Yi Luan
- Clinical Systems Biology Laboratories, Translational Medicine Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Institute of Infection and Immunity, Henan Academy of Innovations in Medical Science, Zhengzhou, China
- Department of Neurology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- NHC Key Laboratory of Prevention and Treatment of Cerebrovascular Diseases, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Wenying Long
- Center for Clinical Research, the Fourth Affiliated Hospital of School of Medicine, and International School of Medicine, International Institutes of Medicine, Zhejiang University, Yiwu, Zhejiang, China
| | - Lisi Dai
- Department of Pathology & Pathophysiology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Department of Surgical Oncology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- School of Basic Medical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Panfeng Tao
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zhifen Deng
- Clinical Systems Biology Laboratories, Translational Medicine Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Institute of Infection and Immunity, Henan Academy of Innovations in Medical Science, Zhengzhou, China
- Department of Neurology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- NHC Key Laboratory of Prevention and Treatment of Cerebrovascular Diseases, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Zongping Xia
- Clinical Systems Biology Laboratories, Translational Medicine Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
- Institute of Infection and Immunity, Henan Academy of Innovations in Medical Science, Zhengzhou, China.
- Department of Neurology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
- NHC Key Laboratory of Prevention and Treatment of Cerebrovascular Diseases, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
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2
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Lan J, Wang Y, Yue S, Xu D, Li Y, Peng X, Hu J, Ju E, He S, Li T. Targeting FoxO proteins induces lytic reactivation of KSHV for treating herpesviral primary effusion lymphoma. PLoS Pathog 2023; 19:e1011581. [PMID: 37594999 PMCID: PMC10468091 DOI: 10.1371/journal.ppat.1011581] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 08/30/2023] [Accepted: 07/27/2023] [Indexed: 08/20/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic virus consisting of both latent and lytic life cycles. Primary effusion lymphoma (PEL) is an aggressive B-cell lineage lymphoma, dominantly latently infected by KSHV. The latent infection of KSHV is persistent and poses an obstacle to killing tumor cells. Like the "shock and kill" strategy designed to eliminate latent HIV reservoir, methods that induce viral lytic reactivation in tumor latently infected by viruses represent a unique antineoplastic strategy, as it could potentially increase the specificity of cytotoxicity in cancer. Inspired by this conception, we proposed that the induction of KSHV lytic reactivation from latency could be a potential therapeutic stratagem for KSHV-associated cancers. Oxidative stress, the clinical hallmark of PEL, is one of the most prominent inducers for KSHV reactivation. Paradoxically, we found that hydrogen peroxide (H2O2) triggers robust cytotoxic effects on KSHV-negative rather than KSHV-positive B lymphoma cells in a dose-dependent manner. Mechanistically, we identified forkhead box protein O1 (FoxO1) and FoxO3 as irrevocable antioxidant defense genes and both of them are upregulated by KSHV latent infection, which is essential for the promoted ROS scavenging in KSHV-positive B lymphoma cells. Pharmacological inhibition or functional knockdown of either FoxO1 or FoxO3 is sufficient to ablate the antioxidant ability and therefore increases the intracellular ROS level that further reverses KSHV from latency to active lytic replication in PEL cells, resulting in tremendous cell death both in vitro and in vivo. Additionally, the elevated level of ROS by inhibiting FoxO proteins further sensitizes PEL cells to ROS-induced apoptosis. Our study therefore demonstrated that the lytic reactivation of KSHV by inhibiting FoxO proteins is a promising therapeutic approach for PEL, which could be further extended to other virus-associated diseases.
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Affiliation(s)
- Jungang Lan
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Laboratory of Animal Nutrition and Human Health, Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Yeqing Wang
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Laboratory of Animal Nutrition and Human Health, Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Shusheng Yue
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Laboratory of Animal Nutrition and Human Health, Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Duo Xu
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Laboratory of Animal Nutrition and Human Health, Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Yinan Li
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Laboratory of Animal Nutrition and Human Health, Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Xiangyu Peng
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Laboratory of Animal Nutrition and Human Health, Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Jiao Hu
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Laboratory of Animal Nutrition and Human Health, Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Enguo Ju
- Center for Nanomedicine, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Shanping He
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Laboratory of Animal Nutrition and Human Health, Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Tingting Li
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Laboratory of Animal Nutrition and Human Health, Hunan Provincial Key Laboratory of Animal Intestinal Function and Regulation, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
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3
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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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Caspase-Mediated Cleavage of the Transcription Factor Sp3: Possible Relevance to Cancer and the Lytic Cycle of Kaposi's Sarcoma-Associated Herpesvirus. Microbiol Spectr 2022; 10:e0146421. [PMID: 35019687 PMCID: PMC8754129 DOI: 10.1128/spectrum.01464-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The open reading frame 50 (ORF50) protein of Kaposi's sarcoma-associated herpesvirus (KSHV) is the master regulator essential for initiating the viral lytic cycle. Previously, we have demonstrated that the ORF50 protein can cooperate with Sp3 to synergistically activate a set of viral and cellular gene promoters through highly conserved ORF50-responsive elements that harbor a Sp3-binding motif. Herein, we show that Sp3 undergoes proteolytic cleavage during the viral lytic cycle, and the cleavage of Sp3 is dependent on caspase activation. Since similar cleavage patterns of Sp3 could be detected in both KSHV-positive and KSHV-negative lymphoma cells undergoing apoptosis, the proteolytic cleavage of Sp3 could be a common event during apoptosis. Mutational analysis identifies 12 caspase cleavage sites in Sp3, which are situated at the aspartate (D) positions D17, D19, D180, D273, D275, D293, D304 (or D307), D326, D344, D530, D543, and D565. Importantly, we noticed that three stable Sp3 C-terminal fragments generated through cleavage at D530, D543, or D565 encompass an intact DNA-binding domain. Like the full-length Sp3, the C-terminal fragments of Sp3 could still retain the ability to cooperate with ORF50 protein to activate specific viral and cellular gene promoters synergistically. Collectively, our findings suggest that despite the proteolytic cleavage of Sp3 under apoptotic conditions, the resultant Sp3 fragments may retain biological activities important for the viral lytic cycle or for cellular apoptosis. IMPORTANCE The ORF50 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) is the key viral protein that controls the switch from latency to lytic reactivation. It is a potent transactivator that can activate target gene promoters via interacting with other cellular DNA-binding transcription factors, such as Sp3. In this report, we show that Sp3 is proteolytically cleaved during the viral lytic cycle, and up to 12 caspase cleavage sites are identified in Sp3. Despite the proteolytic cleavage of Sp3, several resulting C-terminal fragments that have intact zinc-finger DNA-binding domains still retain substantial influence in the synergy with ORF50 to activate specific gene promoters. Overall, our studies elucidate the caspase-mediated cleavage of Sp3 and uncover how ORF50 utilizes the cleavage fragments of Sp3 to transactivate specific viral and cellular gene promoters.
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5
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Cesarman E, Chadburn A, Rubinstein PG. KSHV/HHV8-mediated hematologic diseases. Blood 2022; 139:1013-1025. [PMID: 34479367 PMCID: PMC8854683 DOI: 10.1182/blood.2020005470] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 03/08/2021] [Indexed: 11/20/2022] Open
Abstract
Kaposi sarcoma (KS) herpesvirus (KSHV), also known as human herpesvirus 8, is the causal agent of KS but is also pathogenetically related to several lymphoproliferative disorders, including primary effusion lymphoma (PEL)/extracavitary (EC) PEL, KSHV-associated multicentric Castleman disease (MCD), KSHV+ diffuse large B-cell lymphoma, and germinotropic lymphoproliferative disorder. These different KSHV-associated diseases may co-occur and may have overlapping features. KSHV, similar to Epstein-Barr virus (EBV), is a lymphotropic gammaherpesvirus that is preferentially present in abnormal lymphoid proliferations occurring in immunecompromised individuals. Notably, both KSHV and EBV can infect and transform the same B cell, which is frequently seen in KSHV+ EBV+ PEL/EC-PEL. The mechanisms by which KSHV leads to lymphoproliferative disorders is thought to be related to the expression of a few transforming viral genes that can affect cellular proliferation and survival. There are critical differences between KSHV-MCD and PEL/EC-PEL, the 2 most common KSHV-associated lymphoid proliferations, including viral associations, patterns of viral gene expression, and cellular differentiation stage reflected by the phenotype and genotype of the infected abnormal B cells. Advances in treatment have improved outcomes, but mortality rates remain high. Our deepening understanding of KSHV biology, clinical features of KSHV-associated diseases, and newer clinical interventions should lead to improved and increasingly targeted therapeutic interventions.
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Affiliation(s)
- Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY
| | - Amy Chadburn
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY
| | - Paul G Rubinstein
- Section of Hematology/Oncology, Department of Medicine, John H. Stroger Jr Hospital of Cook County, Chicago, IL; and
- Department of Medicine, Ruth M. Rothstein CORE Center, Rush University Medical Center, Chicago, IL
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Ramos JC, Sparano JA, Chadburn A, Reid EG, Ambinder RF, Siegel ER, Moore PC, Rubinstein PG, Durand CM, Cesarman E, Aboulafia D, Baiocchi R, Ratner L, Kaplan L, Capoferri AA, Lee JY, Mitsuyasu R, Noy A. Impact of Myc in HIV-associated non-Hodgkin lymphomas treated with EPOCH and outcomes with vorinostat (AMC-075 trial). Blood 2020; 136:1284-1297. [PMID: 32430507 PMCID: PMC7483436 DOI: 10.1182/blood.2019003959] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 04/14/2020] [Indexed: 12/11/2022] Open
Abstract
EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin) is a preferred regimen for HIV-non-Hodgkin lymphomas (HIV-NHLs), which are frequently Epstein-Barr virus (EBV) positive or human herpesvirus type-8 (HHV-8) positive. The histone deacetylase (HDAC) inhibitor vorinostat disrupts EBV/HHV-8 latency, enhances chemotherapy-induced cell death, and may clear HIV reservoirs. We performed a randomized phase 2 study in 90 patients (45 per study arm) with aggressive HIV-NHLs, using dose-adjusted EPOCH (plus rituximab if CD20+), alone or with 300 mg vorinostat, administered on days 1 to 5 of each cycle. Up to 1 prior cycle of systemic chemotherapy was allowed. The primary end point was complete response (CR). In 86 evaluable patients with diffuse large B-cell lymphoma (DLBCL; n = 61), plasmablastic lymphoma (n = 15), primary effusion lymphoma (n = 7), unclassifiable B-cell NHL (n = 2), and Burkitt lymphoma (n = 1), CR rates were 74% vs 68% for EPOCH vs EPOCH-vorinostat (P = .72). Patients with a CD4+ count <200 cells/mm3 had a lower CR rate. EPOCH-vorinostat did not eliminate HIV reservoirs, resulted in more frequent grade 4 neutropenia and thrombocytopenia, and did not affect survival. Overall, patients with Myc+ DLBCL had a significantly lower EFS. A low diagnosis-to-treatment interval (DTI) was also associated with inferior outcomes, whereas preprotocol therapy had no negative impact. In summary, EPOCH had broad efficacy against highly aggressive HIV-NHLs, whereas vorinostat had no benefit; patients with Myc-driven DLBCL, low CD4, and low DTI had less favorable outcomes. Permitting preprotocol therapy facilitated accruals without compromising outcomes. This trial was registered at www.clinicaltrials.gov as #NCT0119384.
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MESH Headings
- Adult
- Aged
- Anti-HIV Agents/therapeutic use
- Antineoplastic Combined Chemotherapy Protocols/administration & dosage
- Antineoplastic Combined Chemotherapy Protocols/adverse effects
- Antineoplastic Combined Chemotherapy Protocols/therapeutic use
- CD4 Lymphocyte Count
- Cyclophosphamide/administration & dosage
- Cyclophosphamide/adverse effects
- DNA, Viral/blood
- Doxorubicin/administration & dosage
- Doxorubicin/adverse effects
- Drug Administration Schedule
- Etoposide/administration & dosage
- Etoposide/adverse effects
- Female
- Genes, myc
- HIV Infections/drug therapy
- HIV-1/drug effects
- Herpesviridae Infections/complications
- Herpesviridae Infections/virology
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/isolation & purification
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/isolation & purification
- Histone Deacetylase Inhibitors/administration & dosage
- Histone Deacetylase Inhibitors/adverse effects
- Humans
- Kaplan-Meier Estimate
- Lymphoma, AIDS-Related/complications
- Lymphoma, AIDS-Related/drug therapy
- Lymphoma, AIDS-Related/genetics
- Lymphoma, AIDS-Related/virology
- Lymphoma, Non-Hodgkin/complications
- Lymphoma, Non-Hodgkin/drug therapy
- Lymphoma, Non-Hodgkin/genetics
- Lymphoma, Non-Hodgkin/virology
- Male
- Middle Aged
- Neutropenia/chemically induced
- Prednisone/administration & dosage
- Prednisone/adverse effects
- Progression-Free Survival
- Prospective Studies
- Rituximab/administration & dosage
- Rituximab/adverse effects
- Thrombocytopenia/chemically induced
- Treatment Outcome
- Vincristine/administration & dosage
- Vincristine/adverse effects
- Viral Load/drug effects
- Vorinostat/administration & dosage
- Vorinostat/adverse effects
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Affiliation(s)
- Juan C Ramos
- Department of Medicine, University of Miami School of Medicine, Miami, FL
| | - Joseph A Sparano
- Department of Oncology, Albert Einstein Comprehensive Cancer Center, Bronx, NY
| | - Amy Chadburn
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY
| | - Erin G Reid
- Department of Medicine, University of California, San Diego, San Diego, CA
| | | | - Eric R Siegel
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Page C Moore
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Paul G Rubinstein
- Section of Hematology/Oncology, John H. Stroger Jr Hospital of Cook County, Chicago, IL
| | | | - Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY
| | - David Aboulafia
- Division of Hematology and Oncology, Virginia Mason Medical Center, Seattle, WA
| | - Robert Baiocchi
- Department of Internal Medicine, Ohio State University, Columbus, OH
| | - Lee Ratner
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Lawrence Kaplan
- Department of Medicine, University of California, San Francisco, San Francisco, CA
| | | | - Jeannette Y Lee
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Ronald Mitsuyasu
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA
| | - Ariela Noy
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY; and
- Department of Medicine, Weill Medical College of Cornell University, New York, NY
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7
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Ding L, Zhu Q, Zhou F, Tan H, Xu W, Pan C, Zhu C, Wang Y, Zhang H, Fu W, Qian Z, Yuan Z, Xu H, Wei F, Cai Q. Identification of viral SIM-SUMO2-interaction inhibitors for treating primary effusion lymphoma. PLoS Pathog 2019; 15:e1008174. [PMID: 31830143 PMCID: PMC6932820 DOI: 10.1371/journal.ppat.1008174] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/26/2019] [Accepted: 10/30/2019] [Indexed: 12/19/2022] Open
Abstract
Primary effusion lymphoma (PEL) is an aggressive B-cell malignancy without effective treatment, and caused by the infection of Kaposi’s sarcoma-associated herpesvirus (KSHV), predominantly in its latent form. Previously we showed that the SUMO2-interacting motif within the viral latency-associated nuclear antigen (LANASIM) is essential for establishment and maintenance of KSHV latency. Here, we developed a luciferase based live-cell reporter system to screen inhibitors selectively targeting the interaction between LANASIM and SUMO2. Cambogin, a bioactive natural product isolated from the Garcinia genus (a traditional herbal medicine used for cancer treatment), was obtained from the reporter system screening to efficiently inhibit the association of SUMO2 with LANASIM, in turn reducing the viral episome DNA copy number for establishment and maintenance of KSHV latent infection at a low concentration (nM). Importantly, Cambogin treatments not only specifically inhibited proliferation of KSHV-latently infected cells in vitro, but also induced regression of PEL tumors in a xenograft mouse model. This study has identified Cambogin as a novel therapeutic agent for treating PEL as well as eliminating persistent infection of oncogenic herpesvirus. Primary effusion lymphoma is a common AIDS-associated malignancy caused by infection with Kaposi’s sarcoma-associated herpesvirus (KSHV), and is currently absence of efficient and specific treatment. Natural product from herbal medicines is a major source of drug discovery for the treatment of a variety of diseases. In this study, the authors demonstrated that Cambogin, a polycyclic polyprenylated acylphloroglucinols (PPAPs) isolated from the branches of Garcinia esculenta (a tropical evergreen tree and traditional cancer treatment across Southern Asia), is a potent and effective inhibitor of KSHV-latently infected cells at a low concentration (nM) in vitro and in vivo, through targeting viral LANASIM-SUMO2 interaction.
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Affiliation(s)
- Ling Ding
- MOE& NHC&CAMS Key Laboratory of Medical Molecular Virology, School of Basic Medical Science, Shanghai Medical College, Fudan University, Shanghai, P. R. China
| | - Qing Zhu
- MOE& NHC&CAMS Key Laboratory of Medical Molecular Virology, School of Basic Medical Science, Shanghai Medical College, Fudan University, Shanghai, P. R. China
- ShengYushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Feng Zhou
- Baoji Affiliated Hospital of Xi’an Medical University, Baoji & MOE Key Laboratory of Western Resources and Modern Biotechnology, College of Life Sciences, Northwest University, Xi’an, Shaanxi, China
| | - Hongsheng Tan
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine & Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, China
| | - Wenjia Xu
- Unit of Herpesvirus and Molecular Virology, Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, P. R. China
| | - Chengling Pan
- Beijing Computing Center, Beijing Academy of Science and Technology & Beijing Beike Deyuan Bio-Pharm Technology Company, Beijing, P. R. China
| | - Caixia Zhu
- MOE& NHC&CAMS Key Laboratory of Medical Molecular Virology, School of Basic Medical Science, Shanghai Medical College, Fudan University, Shanghai, P. R. China
| | - Yuyan Wang
- MOE& NHC&CAMS Key Laboratory of Medical Molecular Virology, School of Basic Medical Science, Shanghai Medical College, Fudan University, Shanghai, P. R. China
| | - Hong Zhang
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine & Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, China
| | - Wenwei Fu
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine & Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, China
| | - Zhikang Qian
- Unit of Herpesvirus and Molecular Virology, Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, University of the Chinese Academy of Sciences, Shanghai, P. R. China
| | - Zhenghong Yuan
- MOE& NHC&CAMS Key Laboratory of Medical Molecular Virology, School of Basic Medical Science, Shanghai Medical College, Fudan University, Shanghai, P. R. China
| | - Hongxi Xu
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine & Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, China
- * E-mail: (HX); (FW); (QC)
| | - Fang Wei
- ShengYushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, P. R. China
- * E-mail: (HX); (FW); (QC)
| | - Qiliang Cai
- MOE& NHC&CAMS Key Laboratory of Medical Molecular Virology, School of Basic Medical Science, Shanghai Medical College, Fudan University, Shanghai, P. R. China
- Expert Workstation, Baoji Central Hospital, Baoji, P. R. China
- * E-mail: (HX); (FW); (QC)
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8
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Safety and Preliminary Efficacy of Vorinostat With R-EPOCH in High-risk HIV-associated Non-Hodgkin's Lymphoma (AMC-075). CLINICAL LYMPHOMA MYELOMA & LEUKEMIA 2018; 18:180-190.e2. [PMID: 29426719 PMCID: PMC6697160 DOI: 10.1016/j.clml.2018.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 11/14/2017] [Accepted: 01/16/2018] [Indexed: 01/09/2023]
Abstract
INTRODUCTION Vorinostat (VOR), a histone deacetylase inhibitor, enhances the anti-tumor effects of rituximab (R) and cytotoxic chemotherapy, induces viral lytic expression and cell killing in Epstein-Barr virus-positive (EBV+) or human herpesvirus-8-positive (HHV-8+) tumors, and reactivates latent human immunodeficiency virus (HIV) for possible eradication by combination antiretroviral therapy (cART). PATIENTS AND METHODS We performed a phase I trial of VOR given with R-based infusional EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin hydrochloride) (n = 12) and cART in aggressive HIV-associated B-cell non-Hodgkin lymphoma (NHL) in order to identify safe dosing and schedule. VOR (300 or 400 mg) was given orally on days 1 to 5 with each cycle of R-EPOCH for 10 high-risk patients with diffuse large B-cell lymphoma (1 EBV+), 1 EBV+/HHV-8+ primary effusion lymphoma, and 1 unclassifiable NHL. VOR was escalated from 300 to 400 mg using a standard 3 + 3 design based on dose-limiting toxicity observed in cycle 1 of R-EPOCH. RESULTS The recommended phase II dose of VOR was 300 mg, with dose-limiting toxicity in 2 of 6 patients at 400 mg (grade 4 thrombocytopenia, grade 4 neutropenia), and 1 of 6 treated at 300 mg (grade 4 sepsis from tooth abscess). Neither VOR, nor cART regimen, significantly altered chemotherapy steady-state concentrations. VOR chemotherapy did not negatively impact CD4+ cell counts or HIV viral loads, which decreased or remained undetectable in most patients during treatment. The response rate in high-risk patients with NHL treated with VOR(R)-EPOCH was 100% (complete 83% and partial 17%) with a 1-year event-free survival of 83% (95% confidence interval, 51.6%-97.9%). CONCLUSION VOR combined with R-EPOCH was tolerable and seemingly efficacious in patients with aggressive HIV-NHL.
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Tsai CY, Chen CY, Chiou YH, Shyu HW, Lin KH, Chou MC, Huang MH, Wang YF. Epigallocatechin-3-Gallate Suppresses Human Herpesvirus 8 Replication and Induces ROS Leading to Apoptosis and Autophagy in Primary Effusion Lymphoma Cells. Int J Mol Sci 2017; 19:ijms19010016. [PMID: 29267216 PMCID: PMC5795967 DOI: 10.3390/ijms19010016] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 12/15/2017] [Accepted: 12/18/2017] [Indexed: 12/02/2022] Open
Abstract
Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, has been shown to induce cell death in cancer cells. Primary effusion lymphoma (PEL) is an aggressive neoplasm caused by human herpesvirus 8 (HHV8). In this study, we examined the role of EGCG on PEL cells in cell death and HHV8 replication. We performed trypan blue exclusion assay to assess the cell viability of PEL cells, flow cytometry analysis to examine the cell cycle distribution and reactive oxygen species (ROS) generation, caspase-3 activity to assay apoptosis, acridine orange staining to determine autophagy, and immunoblotting to detect the protein levels involved in apoptosis and autophagy as well as mitogen activated protein kinases (MAPKs) activation upon EGCG treatment. The expression of the HHV8 lytic gene was determined by luciferase reporter assay and reverse transcription-PCR, and viral progeny production was determined by PCR. Results revealed that EGCG induced cell death and ROS generation in PEL cells in a dose-dependent manner. N-acetylcysteine (NAC) inhibited the EGCG-induced ROS and rescued the cell from EGCG-induced cell death. Even though EGCG induced ROS generation in PEL cells, it reduced the production of progeny virus from PEL cells without causing HHV8 reactivation. These results suggest that EGCG may represent a novel strategy for the treatment of HHV8 infection and HHV8-associated lymphomas.
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Affiliation(s)
- Ching-Yi Tsai
- Department of Medical Laboratory Science and Biotechnology, Fooyin-University, Kaohsiung 83102, Taiwan.
| | - Chang-Yu Chen
- Department of Medical Laboratory Science and Biotechnology, Fooyin-University, Kaohsiung 83102, Taiwan.
| | - Yee-Hsuan Chiou
- Department of Pediatrics, Kaohsiung Veterans General Hospital, Kaohsiung 83102, Taiwan.
| | - Huey-Wen Shyu
- Department of Medical Laboratory Science and Biotechnology, Fooyin-University, Kaohsiung 83102, Taiwan.
| | - Kuan-Hua Lin
- Department of Medical Laboratory Science and Biotechnology, Fooyin-University, Kaohsiung 83102, Taiwan.
| | - Miao-Chen Chou
- Department of Medical Laboratory Science and Biotechnology, Fooyin-University, Kaohsiung 83102, Taiwan.
| | - Mei-Han Huang
- Department of Medical Laboratory Science and Biotechnology, Fooyin-University, Kaohsiung 83102, Taiwan.
| | - Yi-Fen Wang
- Department of Medical Laboratory Science and Biotechnology, Fooyin-University, Kaohsiung 83102, Taiwan.
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Viral microRNAs Target a Gene Network, Inhibit STAT Activation, and Suppress Interferon Responses. Sci Rep 2017; 7:40813. [PMID: 28102325 PMCID: PMC5244407 DOI: 10.1038/srep40813] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 12/12/2016] [Indexed: 12/13/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) encodes 12 pre-microRNAs during latency that are processed to yield ~25 mature microRNAs (miRNAs). We were interested in identifying cellular networks that were targeted by KSHV-miRNAs and employed network building strategies using validated KSHV miRNA targets. Here, we report the identification of a gene network centering on the transcription factor- signal transducer and activator of transcription 3 (STAT3) that is targeted by KSHV miRNAs. KSHV miRNAs suppressed STAT3 and STAT5 activation and inhibited STAT3-dependent reporter activation upon IL6-treatment. KSHV miRNAs also repressed the induction of antiviral interferon-stimulated genes upon IFNα- treatment. Finally, we observed increased lytic reactivation of KSHV from latently infected cells upon STAT3 repression with siRNAs or a small molecule inhibitor. Our data suggest that treatment of infected cells with a STAT3 inhibitor and a viral replication inhibitor, ganciclovir, represents a possible strategy to eliminate latently infected cells without increasing virion production. Together, we show that KSHV miRNAs suppress a network of targets associated with STAT3, deregulate cytokine-mediated gene activation, suppress an interferon response, and influence the transition into the lytic phase of viral replication.
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Kaposi's sarcoma-associated herpesvirus: the role of lytic replication in targeted therapy. Curr Opin Infect Dis 2016; 28:611-24. [PMID: 26524334 DOI: 10.1097/qco.0000000000000213] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE OF REVIEW To discuss the role of Kaposi's sarcoma-associated herpesvirus (KSHV) lytic replication in viral-associated diseases and assess the progress on targeting KSHV lytic replication as a strategy to prevent KSHV-related malignancies. RECENT FINDINGS New inhibitors of viral lytic replication are being developed as well as novel modalities are being investigated to target cellular processes that the virus hijacks during its life cycle. Research has also focused on reactivating viral lytic replication in latently infected tumour cells (lytic induction therapy) to promote death of tumour cells. SUMMARY KSHV is linked to three malignancies: Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman disease. Despite significant progress in understanding KSHV pathobiology, no therapeutic guidelines for the management of KSHV-related diseases exist, and current treatments are suboptimal and associated with toxicity. Antiherpesvirus drugs have shown inconsistent results in KSHV-associated malignancies that harbour the virus in a latent state. However, lytic replication plays a crucial role in the process of tumorigenesis. Therefore, not only antiviral agents directed against the virus replicative cycle but also agents that target cellular processes that are activated by the virus are being investigated. Antivirals may also be used in combination with inducers of the viral lytic stage.
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A role for MALT1 activity in Kaposi's sarcoma-associated herpes virus latency and growth of primary effusion lymphoma. Leukemia 2016; 31:614-624. [PMID: 27538487 PMCID: PMC5339436 DOI: 10.1038/leu.2016.239] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/20/2016] [Accepted: 08/09/2016] [Indexed: 12/15/2022]
Abstract
Primary effusion lymphoma (PEL) is an incurable malignancy that develops in immunodeficient patients as a consequence of latent infection of B-cells with Kaposi's sarcoma-associated herpes virus (KSHV). Malignant growth of KSHV-infected B cells requires the activity of the transcription factor nuclear factor (NF)-κB, which controls maintenance of viral latency and suppression of the viral lytic program. Here we show that the KSHV proteins K13 and K15 promote NF-κB activation via the protease mucosa-associated lymphoid tissue lymphoma translocation protein-1 (MALT1), a key driver of NF-κB activation in lymphocytes. Inhibition of the MALT1 protease activity induced a switch from the latent to the lytic stage of viral infection, and led to reduced growth and survival of PEL cell lines in vitro and in a xenograft model. These results demonstrate a key role for the proteolytic activity of MALT1 in PEL, and provide a rationale for the pharmacological targeting of MALT1 in PEL therapy.
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Abstract
Kaposi’s sarcoma (KS)-associated herpesvirus (KSHV) is an oncogenic human herpesvirus. KSHV is associated with three cancers in the human population: KS, primary effusion lymphoma (PEL), and multicentric Castleman’s disease (MCD). KS is the leading cause of cancer in HIV-infected individuals. In this review, we discuss the most recent discoveries behind the mechanisms of KSHV latency maintenance and lytic replication. We also review current therapies for KSHV-associated cancers.
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Affiliation(s)
- Nathan J Dissinger
- Lineberger Comprehensive Cancer Center and Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Blossom Damania
- Lineberger Comprehensive Cancer Center and Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Kang H, Song J, Choi K, Kim H, Choi M, Lee SY, Kim C, Lee SJ, Song MJ, Kang H, Back SH, Han SB, Cho S. Efficient lytic induction of Kaposi's sarcoma-associated herpesvirus (KSHV) by the anthracyclines. Oncotarget 2015; 5:8515-27. [PMID: 25237786 PMCID: PMC4226701 DOI: 10.18632/oncotarget.2335] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Lytic induction of latent Kaposi's sarcoma-associated herpesvirus (KSHV) has been considered as a therapeutic option for efficient treatment of several KSHV-associated malignancies. Here, we developed a robust high-throughput screening system that allows an easy and quantitative measurement of lytic induction of latent KSHV and discovered three anthracyclines as potent inducers from screen of FDA-approved drugs. Lytic induction of latent KSHV by three compounds was verified by the significant induction of lytic genes and subsequent production of infectious KSHV. Importantly, lytic induction by three compounds was much more efficient than that by sodium butyrate, a well-characterized inducer of KSHV lytic cycle. Mechanistically, the anthracyclines caused lytic induction of KSHV through apoptosis induced by their DNA intercalation rather than topoisomerase II inhibition. Consequently, our results clearly demonstrated a role of anthracyclines as effective lytic inducers of KSHV and also provided a molecular basis of their use for efficient treatment of diseases associated with KSHV infection.
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Affiliation(s)
- Hyunju Kang
- Targeted Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongwon, Chungbuk, Republic of Korea. College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Jaehyung Song
- College of Pharmacy, Kangwon National University, Chuncheon, Republic of Korea
| | - Kwangman Choi
- Targeted Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongwon, Chungbuk, Republic of Korea. Department of Medical Biotechnology, Soonchunhyang University, Asan, Republic of Korea
| | - Hyeongki Kim
- Targeted Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongwon, Chungbuk, Republic of Korea. Department of Biomolecular Science, University of Science and Technology, Daejeon, Republic of Korea
| | - Miri Choi
- Targeted Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongwon, Chungbuk, Republic of Korea
| | - So-Young Lee
- International Cooperation Office, Ministry of Food and Drug Safety, Cheongwon, Chungbuk, Republic of Korea
| | - Chonsaeng Kim
- Virus Research and Testing Group, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
| | - Sang Jun Lee
- Infection and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea
| | - Moon Jung Song
- Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Hyojeung Kang
- College of Pharmacy, Research Institute of Pharmaceutical Sciences, and Institute for Microorganisms, Kyungpook National University, Daegu, Republic of Korea
| | - Sung Hoon Back
- School of Biological Sciences, University of Ulsan, Ulsan, Republic of Korea
| | - Sang-Bae Han
- College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Sungchan Cho
- Targeted Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongwon, Chungbuk, Republic of Korea. Department of Biomolecular Science, University of Science and Technology, Daejeon, Republic of Korea
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Klepfish A, Zuckermann B, Schattner A. Primary effusion lymphoma in the absence of HIV infection--clinical presentation and management. QJM 2015; 108:481-8. [PMID: 25413797 DOI: 10.1093/qjmed/hcu232] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Indexed: 01/13/2023] Open
Abstract
Primary Effusion Lymphoma (PEL) is a rare type of Non-Hodgkin's Lymphoma caused by human herpesvirus type 8, also termed Kaposi's sarcoma-associated herpesvirus. It usually occurs in human immunodeficiency virus (HIV)-infected patients. A subset of patients is not infected with HIV and their treatment remains poorly defined. To clarify treatment issues in HIV-negative PEL patients, we report on two such patients who represent two opposing ends in the spectrum of treatment and review the literature regarding treatment options and patient outcomes. Either repeated cycles of chemotherapy or, surprisingly, drainage of the malignant effusions alone, proved very effective in our patients. The literature reveals additional treatment options which may be effective including immunochemotherapy, stem cell transplantation, antiviral treatment and immunomodulatory and targeted biological therapy. However, no controlled trials were found due to the rarity of the condition. In the absence of controlled trials, treatment decisions in PEL not associated with HIV must remain individual and patient-tailored.
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Affiliation(s)
- A Klepfish
- From the Blood Bank and Department of Hematology, Department of Cardio-Thoracic Surgery, Edith Wolfson Medical Centre, Holon and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv and The Faculty of Medicine, Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - B Zuckermann
- From the Blood Bank and Department of Hematology, Department of Cardio-Thoracic Surgery, Edith Wolfson Medical Centre, Holon and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv and The Faculty of Medicine, Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - A Schattner
- From the Blood Bank and Department of Hematology, Department of Cardio-Thoracic Surgery, Edith Wolfson Medical Centre, Holon and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv and The Faculty of Medicine, Hebrew University Hadassah Medical School, Jerusalem, Israel
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Coen N, Duraffour S, Snoeck R, Andrei G. KSHV targeted therapy: an update on inhibitors of viral lytic replication. Viruses 2014; 6:4731-59. [PMID: 25421895 PMCID: PMC4246246 DOI: 10.3390/v6114731] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 11/07/2014] [Accepted: 11/17/2014] [Indexed: 01/01/2023] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi’s sarcoma, primary effusion lymphoma and multicentric Castleman’s disease. Since the discovery of KSHV 20 years ago, there is still no standard treatment and the management of virus-associated malignancies remains toxic and incompletely efficacious. As the majority of tumor cells are latently infected with KSHV, currently marketed antivirals that target the virus lytic cycle have shown inconsistent results in clinic. Nevertheless, lytic replication plays a major role in disease progression and virus dissemination. Case reports and retrospective studies have pointed out the benefit of antiviral therapy in the treatment and prevention of KSHV-associated diseases. As a consequence, potent and selective antivirals are needed. This review focuses on the anti-KSHV activity, mode of action and current status of antiviral drugs targeting KSHV lytic cycle. Among these drugs, different subclasses of viral DNA polymerase inhibitors and compounds that do not target the viral DNA polymerase are being discussed. We also cover molecules that target cellular kinases, as well as the potential of new drug targets and animal models for antiviral testing.
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Affiliation(s)
- Natacha Coen
- Rega Institute for Medical Research, KU Leuven, B-3000 Leuven, Belgium.
| | - Sophie Duraffour
- Rega Institute for Medical Research, KU Leuven, B-3000 Leuven, Belgium.
| | - Robert Snoeck
- Rega Institute for Medical Research, KU Leuven, B-3000 Leuven, Belgium.
| | - Graciela Andrei
- Rega Institute for Medical Research, KU Leuven, B-3000 Leuven, Belgium.
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Goto H, Kudo E, Kariya R, Taura M, Katano H, Okada S. Targeting VEGF and interleukin-6 for controlling malignant effusion of primary effusion lymphoma. J Cancer Res Clin Oncol 2014; 141:465-74. [PMID: 25304617 DOI: 10.1007/s00432-014-1842-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 09/27/2014] [Indexed: 02/07/2023]
Abstract
PURPOSE Primary effusion lymphoma (PEL) is an aggressive subtype of non-Hodgkin lymphoma that shows malignant effusion most commonly seen in advanced AIDS patients. In this study, we clarified the potential role of VEGF and IL-6 in PEL fluid retention and evaluated the efficacy of humanized anti-VEGF monoclonal antibody (mAb), bevacizumab, and humanized anti-IL-6 receptor mAb, tocilizumab, against PEL. METHODS The production of VEGF and IL-6, and the expression of IL-6Rα in PEL cell lines were examined. The antiproliferative effect of bevacizumab and tocilizumab on PEL cells was evaluated in vitro. The effect of tocilizumab on VEGF was also examined. An intraperitoneal xenograft mouse model was used for in vivo efficacy. RESULTS Although we found the production of VEGF and IL-6, and the expression of IL-6Rα in PEL cell lines, bevacizumab and tocilizumab did not inhibit the proliferation of PEL cells in vitro. Tocilizumab decreased VEGF mRNA and VEGF production by inhibiting Stat3 phosphorylation and Stat3 binding to VEGF promoter. In a PEL xenograft mouse model that showed profuse ascites, bevacizumab suppressed ascites formation completely, indicating the critical role of VEGF for PEL fluid retention. Tocilizumab also significantly inhibited ascites formation in vivo. Moreover, these mAbs improved the overall survival of treated mice. CONCLUSIONS IL-6-VEGF axis contributed to fluid retention, and bevacizumab and tocilizumab could be effective molecular targeting therapies for PEL.
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Affiliation(s)
- Hiroki Goto
- Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811, Japan
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Pyrrolidinium fullerene induces apoptosis by activation of procaspase-9 via suppression of Akt in primary effusion lymphoma. Biochem Biophys Res Commun 2014; 451:93-100. [DOI: 10.1016/j.bbrc.2014.07.068] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 07/15/2014] [Indexed: 11/23/2022]
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Wakao K, Watanabe T, Takadama T, Ui S, Shigemi Z, Kagawa H, Higashi C, Ohga R, Taira T, Fujimuro M. Sangivamycin induces apoptosis by suppressing Erk signaling in primary effusion lymphoma cells. Biochem Biophys Res Commun 2014; 444:135-40. [PMID: 24434142 DOI: 10.1016/j.bbrc.2014.01.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 01/08/2014] [Indexed: 01/24/2023]
Abstract
Sangivamycin, a structural analog of adenosine and antibiotic exhibiting antitumor and antivirus activities, inhibits protein kinase C and the synthesis of both DNA and RNA. Primary effusion lymphoma (PEL) is an aggressive neoplasm caused by Kaposi's sarcoma-associated herpesvirus (KSHV) in immunosuppressed patients and HIV-infected homosexual males. PEL cells are derived from post-germinal center B cells, and are infected with KSHV. Herein, we asked if sangivamycin might be useful to treat PEL. We found that sangivamycin killed PEL cells, and we explored the underlying mechanism. Sangivamycin treatment drastically decreased the viability of PEL cell lines compared to KSHV-uninfected B lymphoma cell lines. Sangivamycin induced the apoptosis of PEL cells by activating caspase-7 and -9. Further, sangivamycin suppressed the phosphorylation of Erk1/2 and Akt, thus inhibiting activation of the proteins. Inhibitors of Akt and MEK suppressed the proliferation of PEL cells compared to KSHV-uninfected cells. It is known that activation of Erk and Akt signaling inhibits apoptosis and promotes proliferation in PEL cells. Our data therefore suggest that sangivamycin induces apoptosis by inhibiting Erk and Akt signaling in such cells. We next investigated whether sangivamycin, in combination with an HSP90 inhibitor geldanamycin (GA) or valproate (valproic acid), potentiated the cytotoxic effects of the latter drugs on PEL cells. Compared to treatment with GA or valproate alone, the addition of sangivamycin enhanced cytotoxic activity. Our data thus indicate that sangivamycin may find clinical utility as a novel anti-cancer agent targeting PEL.
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Affiliation(s)
- Kazufumi Wakao
- Department of Biotechnology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Kofu-shi 400-8511, Japan
| | - Tadashi Watanabe
- Department of Cell Biology, Kyoto Pharmaceutical University, Misasagi-Shichonocho 1, Yamashinaku, Kyoto 607-8412, Japan
| | - Tadatoshi Takadama
- Department of Biotechnology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Kofu-shi 400-8511, Japan
| | - Sadaharu Ui
- Department of Biotechnology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Kofu-shi 400-8511, Japan
| | - Zenpei Shigemi
- Department of Cell Biology, Kyoto Pharmaceutical University, Misasagi-Shichonocho 1, Yamashinaku, Kyoto 607-8412, Japan
| | - Hiroki Kagawa
- Department of Cell Biology, Kyoto Pharmaceutical University, Misasagi-Shichonocho 1, Yamashinaku, Kyoto 607-8412, Japan
| | - Chizuka Higashi
- Department of Molecular Cell Biology, Faculty of Medicine, University of Yamanashi, Chuoh-shi 409-3898, Japan
| | - Rie Ohga
- Department of Molecular Cell Biology, Faculty of Medicine, University of Yamanashi, Chuoh-shi 409-3898, Japan
| | - Takahiro Taira
- Department of Molecular Cell Biology, Faculty of Medicine, University of Yamanashi, Chuoh-shi 409-3898, Japan
| | - Masahiro Fujimuro
- Department of Cell Biology, Kyoto Pharmaceutical University, Misasagi-Shichonocho 1, Yamashinaku, Kyoto 607-8412, Japan.
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Yin CC, Jones D. Molecular approaches towards characterization, monitoring and targeting of viral-associated hematological malignancies. Expert Rev Mol Diagn 2014; 6:831-41. [PMID: 17140370 DOI: 10.1586/14737159.6.6.831] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Viral-associated malignancies usually arise in the setting of altered immunity or with declines in immune function associated with aging. The main culprits are the lymphotropic herpesvirus, including Epstein-Barr virus (EBV) and human herpesvirus-8, which are the focus of this review. Chronic persistent infection and viral reactivation are the main risk factors for development of herpesvirus-associated malignancies and have provided the rationale for intensive monitoring of viral loads in some clinical contexts. Quantitative detection of EBV levels in the post-transplant period and following treatment of EBV-associated malignancies now have a proven role in outcome prediction. Both T-cell immunotherapy and humoral immunotherapies directed against latent viral antigens represent promising interventional approaches to treatment of viral-associated malignancies.
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Affiliation(s)
- C Cameron Yin
- The University of Texas MD Anderson Cancer Center, Department of Hematopathology, Houston, TX, 77030, USA.
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Bhatt S, Ashlock BM, Natkunam Y, Sujoy V, Chapman JR, Ramos JC, Mesri EA, Lossos IS. CD30 targeting with brentuximab vedotin: a novel therapeutic approach to primary effusion lymphoma. Blood 2013; 122:1233-42. [PMID: 23838350 PMCID: PMC3744990 DOI: 10.1182/blood-2013-01-481713] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 06/25/2013] [Indexed: 12/24/2022] Open
Abstract
Primary effusion lymphoma (PEL) is an aggressive subtype of non-Hodgkin lymphoma characterized by short survival with current therapies, emphasizing the urgent need to develop new therapeutic approaches. Brentuximab vedotin (SGN-35) is an anti-CD30 monoclonal antibody (cAC10) conjugated by a protease-cleavable linker to a microtubule-disrupting agent, monomethyl auristatin E. Brentuximab vedotin is an effective treatment of relapsed CD30-expressing Classical Hodgkin and systemic anaplastic large cell lymphomas. Herein, we demonstrated that PEL cell lines and primary tumors express CD30 and thus may serve as potential targets for brentuximab vedotin therapy. In vitro treatment with brentuximab vedotin decreased cell proliferation, induced cell cycle arrest, and triggered apoptosis of PEL cell lines. Furthermore, in vivo brentuximab vedotin promoted tumor regression and prolonged survival of mice bearing previously reported UM-PEL-1 tumors as well as UM-PEL-3 tumors derived from a newly established and characterized Kaposi's sarcoma-associated herpesvirus- and Epstein-Barr virus-positive PEL cell line. Overall, our results demonstrate for the first time that brentuximab vedotin may serve as an effective therapy for PEL and provide strong preclinical indications for evaluation of brentuximab vedotin in clinical studies of PEL patients.
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Affiliation(s)
- Shruti Bhatt
- Department of Molecular and Cellular Pharmacology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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Bhatt S, Ashlock BM, Toomey NL, Diaz LA, Mesri EA, Lossos IS, Ramos JC. Efficacious proteasome/HDAC inhibitor combination therapy for primary effusion lymphoma. J Clin Invest 2013; 123:2616-28. [PMID: 23635777 DOI: 10.1172/jci64503] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 02/28/2013] [Indexed: 12/26/2022] Open
Abstract
Primary effusion lymphoma (PEL) is a rare form of aggressive B cell lymphoma caused by Kaposi's sarcoma-associated herpesvirus (KSHV). Current chemotherapy approaches result in dismal outcomes, and there is an urgent need for new PEL therapies. Previously, we established, in a direct xenograft model of PEL-bearing immune-compromised mice, that treatment with the proteasome inhibitor, bortezomib (Btz), increased survival relative to that after treatment with doxorubicin. Herein, we demonstrate that the combination of Btz with the histone deacetylase (HDAC) inhibitor suberoylanilidehydroxamic acid (SAHA, also known as vorinostat) potently reactivates KSHV lytic replication and induces PEL cell death, resulting in significantly prolonged survival of PEL-bearing mice. Importantly, Btz blocked KSHV late lytic gene expression, terminally inhibiting the full lytic cascade and production of infectious virus in vivo. Btz treatment led to caspase activation and induced DNA damage, as evidenced by the accumulation of phosphorylated γH2AX and p53. The addition of SAHA to Btz treatment was synergistic, as SAHA induced early acetylation of p53 and reduced interaction with its negative regulator MDM2, augmenting the effects of Btz. The eradication of KSHV-infected PEL cells without increased viremia in mice provides a strong rationale for using the proteasome/HDAC inhibitor combination therapy in PEL.
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Affiliation(s)
- Shruti Bhatt
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
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Goto H, Matsuda K, Srikoon P, Kariya R, Hattori S, Taura M, Katano H, Okada S. Potent antitumor activity of zoledronic acid-induced Vγ9Vδ2 T cells against primary effusion lymphoma. Cancer Lett 2013; 331:174-82. [DOI: 10.1016/j.canlet.2012.12.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 12/10/2012] [Accepted: 12/25/2012] [Indexed: 11/29/2022]
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Establishment of a CD4-positive cell line from an AIDS-related primary effusion lymphoma. Int J Hematol 2013; 97:624-33. [PMID: 23605439 DOI: 10.1007/s12185-013-1339-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 04/10/2013] [Accepted: 04/11/2013] [Indexed: 10/26/2022]
Abstract
Primary effusion lymphoma (PEL) presents as a serous lymphomatous effusion without tumor masses exclusively in body cavities and mainly occurs in human immunodeficiency virus-1 (HIV-1)-infected patients. We established a new PEL cell line, designated GTO, from the pericardial effusion of a 39-year-old Japanese patient with acquired immunodeficiency syndrome-related PEL. This cell line was infected with human herpesvirus-8, but not with Epstein-Barr virus. Southern blot hybridization demonstrated that GTO cells display monoclonal rearrangement of the IgH gene, suggesting clonal B cell proliferation. GTO cells weakly express or lack T cell-associated markers (CD3, CD5, CD8), the majority of B cell-associated markers (CD19, CD20, CD21, CD79a), the α chains of β 2 integrins (CD11a, CD11b, CD11c), HLA-DR, CD30, and surface immunoglobulin (sIgM, sIgG sIgκ, sIgλ), TCR (α/β, γδ), but express CD45, and post-germinal center B cell/plasma cell-associated antigens (CD38, CD138). They also express a high level of cell-surface CD4 and can be infected by HIV-1. Immunodeficient mice intraperitoneally xenografted with GTO cells developed ascites containing lymphoma cells. The establishment of GTO and a GTO xenograft mouse model may help to provide insights toward a better understanding of the pathogenesis of PEL and the relationship between HIV-1 and HHV-8.
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Abstract
The long-lasting persistence of hepatitis B virus (HBV) genomes in the liver (with detectable or undetectable HBV DNA in the serum) of individuals testing negative for the HBV surface antigen (HBsAg) is termed occult HBV infection (OBI). Although in a minority of cases the lack of HBsAg detection is due to infection with variant viruses unrecognized by available assays (S-escape mutants), the typical OBI is related to replication-competent HBVs strongly suppressed in their replication activity. The causes of HBV suppression are not yet well clarified, although the host's immune surveillance and epigenetic mechanisms are likely involved. OBI is a worldwide diffused entity, but the available data of prevalence in various categories of individuals are often contrasting because of the different sensitivity and specificity of the methods used for its detection in many studies. OBI may have an impact in several different clinical contexts. In fact, it can be transmitted (i.e., through blood transfusion and liver transplantation) causing classic forms of hepatitis B in newly infected individuals. The development of an immunosuppressive status (mainly by immunotherapy or chemotherapy) may induce OBI reactivation and development of acute and often severe hepatitis. Finally, evidence suggests that OBI can favor the progression of liver fibrosis, in particular in HCV-infected patients. The possible contribution of OBI to the establishment of cirrhosis also implies its possible indirect role in the development of hepatocellular carcinoma. On the other hand, OBI may maintain most of the direct transforming properties of the overt HBV infection, such as the capacity to integrate in the host's genome and to synthesize pro-oncogenic proteins.
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Iwata S, Saito T, Ito Y, Kamakura M, Gotoh K, Kawada JI, Nishiyama Y, Kimura H. Antitumor activities of valproic acid on Epstein-Barr virus-associated T and natural killer lymphoma cells. Cancer Sci 2011; 103:375-81. [PMID: 22017376 DOI: 10.1111/j.1349-7006.2011.02127.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Epstein-Barr virus (EBV), which infects B cells, T cells, and natural killer (NK) cells, is associated with multiple lymphoid malignancies. Recently, histone deacetylase (HDAC) inhibitors have been reported to have anticancer effects against various tumor cells. In the present study, we evaluated the killing effect of valproic acid (VPA), which acts as an HDAC inhibitor, on EBV-positive and -negative T and NK lymphoma cells. Treatment of multiple T and NK cell lines (SNT13, SNT16, Jurkat, SNK6, KAI3 and KHYG1) with 0.1-5 mM of VPA inhibited HDAC, increased acetylated histone levels and reduced cell viability. No significant differences were seen between EBV-positive and -negative cell lines. Although VPA induced apoptosis in some T and NK cell lines (SNT16, Jurkat and KHYG1) and cell cycle arrest, it did not induce lytic infection in EBV-positive T or NK cell lines. Because the killing effect of VPA was modest (1 mM VPA reduced cell viability by between 22% and 56%), we tested the effects of the combination of 1 mM of VPA and 0.01 μM of the proteasome inhibitor bortezomib. The combined treated of cells with VPA and bortezomib had an additive killing effect. Finally, we administered VPA to peripheral blood mononuclear cells from three patients with EBV-associated T or NK lymphoproliferative diseases. In these studies, VPA had a greater killing effect against EBV-infected cells than uninfected cells, and the effect was increased when VPA was combined with bortezomib. These results indicate that VPA has antitumor effects on T and NK lymphoma cells and that VPA and bortezomib may have synergistic effects, irrespective of the presence of EBV.
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Affiliation(s)
- Seiko Iwata
- Departments of Virology Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Gantt S, Casper C. Human herpesvirus 8-associated neoplasms: the roles of viral replication and antiviral treatment. Curr Opin Infect Dis 2011; 24:295-301. [PMID: 21666458 PMCID: PMC4059200 DOI: 10.1097/qco.0b013e3283486d04] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE OF REVIEW In this review, we highlight the importance of human herpesvirus 8 (HHV-8) lytic replication and the potential for antiviral therapies to prevent or treat HHV-8-related neoplasms. RECENT FINDINGS Diseases caused by HHV-8 infection include Kaposi sarcoma, multicentric Castleman disease (MCD), and primary effusion lymphoma (PEL), which occur primarily in patients with HIV infection. Kaposi sarcoma is the most common AIDS-associated malignancy worldwide. MCD and PEL occur less commonly but, like Kaposi sarcoma, are associated with poor treatment outcomes. Like all herpesviruses, HHV-8 is capable of either latent or lytic infection of cells. Although HHV-8 infection of tumor cells is predominately latent, accumulating data point to the importance of both lytic phase viral gene products and production of infectious virus. Antiviral agents that target herpesvirus DNA synthesis, such as ganciclovir, inhibit HHV-8 lytic replication and can prevent Kaposi sarcoma. Several HIV protease inhibitors may interfere with tumor growth and angiogenesis, and one protease inhibitor, nelfinavir, directly inhibits HHV-8 replication in vitro. SUMMARY Controlled trials are indicated to determine the clinical utility of antiviral suppression of HHV-8 replication, and identify the optimal antiretroviral regimens, for the prevention and treatment of Kaposi sarcoma.
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Affiliation(s)
- Soren Gantt
- Department of Pediatrics, University of Washington, Seattle Children's Hospital, Seattle, WA 98101, USA.
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Bortezomib induction of C/EBPβ mediates Epstein-Barr virus lytic activation in Burkitt lymphoma. Blood 2011; 117:6297-303. [PMID: 21447826 DOI: 10.1182/blood-2011-01-332379] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Epstein-Barr virus (EBV) is associated with a variety of lymphoid malignancies. Bortezomib activates EBV lytic gene expression. Bortezomib, a proteasome inhibitor, leads to increased levels of CCAAT/enhancer-binding proteinβ (C/EBPβ) in a variety of tumor cell lines. C/EBPβ activates the promoter of the EBV lytic switch gene ZTA. Bortezomib treatment leads to increased binding of C/EBP to previously recognized binding sites in the ZTA promoter. Knockdown of C/EBPβ inhibits bortezomib activation of EBV lytic gene expression. Bortezomib also induces the unfolded protein response (UPR), as evidenced by increases in ATF4, CHOP10, and XBP1s and cleavage of ATF6. Thapsigargin, an inducer of the UPR that does not interfere with proteasome function, also induces EBV lytic gene expression. The effects of thapsigargin on EBV lytic gene expression are also inhibited by C/EBPβ knock-down. Therefore, C/EBPβ mediates the activation of EBV lytic gene expression associated with bortezomib and another UPR inducer.
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Rao RC, Chen DF, Miller JW. An epigenetic approach toward understanding ocular α-herpesvirus pathogenesis and treatment. Int Ophthalmol Clin 2011; 51:117-133. [PMID: 21897145 DOI: 10.1097/iio.0b013e31822d6966] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- Rajesh C Rao
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA
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Spina M, Gloghini A, Tirelli U, Carbone A. Therapeutic options for HIV-associated lymphomas. Expert Opin Pharmacother 2010; 11:2471-81. [DOI: 10.1517/14656566.2010.502528] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Efficacy of bortezomib in a direct xenograft model of primary effusion lymphoma. Proc Natl Acad Sci U S A 2010; 107:13069-74. [PMID: 20615981 DOI: 10.1073/pnas.1002985107] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Primary effusion lymphoma (PEL) is an aggressive B-cell lymphoma most commonly diagnosed in HIV-positive patients and universally associated with Kaposi's sarcoma-associated herpesvirus (KSHV). Chemotherapy treatment of PEL yields only short-term remissions in the vast majority of patients, but efforts to develop superior therapeutic approaches have been impeded by lack of animal models that accurately mimic human disease. To address this issue, we developed a direct xenograft model, UM-PEL-1, by transferring freshly isolated human PEL cells into the peritoneal cavities of NOD/SCID mice without in vitro cell growth to avoid the changes in KSHV gene expression evident in cultured cells. We used this model to show that bortezomib induces PEL remission and extends overall survival of mice bearing lymphomatous effusions. The proapoptotic effects of bortezomib are not mediated by inhibition of the prosurvival NF-kappaB pathway or by induction of a terminal unfolded protein response. Transcriptome analysis by genomic arrays revealed that bortezomib down-regulated cell-cycle progression, DNA replication, and Myc-target genes. Furthermore, we demonstrate that in vivo treatment with either bortezomib or doxorubicin induces KSHV lytic reactivation. These reactivations were temporally distinct, and this difference may help elucidate the therapeutic window for use of antivirals concurrently with chemotherapy. Our findings show that this direct xenograft model can be used for testing novel PEL therapeutic strategies and also can provide a rational basis for evaluation of bortezomib in clinical trials.
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Hui KF, Chiang AKS. Suberoylanilide hydroxamic acid induces viral lytic cycle in Epstein-Barr virus-positive epithelial malignancies and mediates enhanced cell death. Int J Cancer 2010; 126:2479-89. [PMID: 19816947 DOI: 10.1002/ijc.24945] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
In Epstein-Barr virus (EBV)-associated malignancies, the virus is harbored in every tumor cell and persists in tightly latent forms expressing a very limited number of viral latent proteins. Induction of EBV lytic cycle leads to expression of a much larger number of viral proteins, which may serve as potential therapeutic targets. We found that 4 histone deacetylase inhibitors, trichostatin A (TSA), sodium butyrate (SB), valproic acid (VPA) and suberoylanilide hydroxamic acid (SAHA), all significantly induced EBV lytic cycle in EBV-positive gastric carcinoma cells (AGS/BX1, latency II) but only weakly induced in Burkitt lymphoma cells (AK2003, latency I) and did not induce in lymphoblastoid cells (LCLs, latency III). Interestingly, SAHA potently induced viral lytic cycle in AGS/BX1 cells at micromolar concentrations (evidenced by 8-fold increase in viral DNA replication, strong expression of viral lytic proteins and production of infectious virus particles) and mediated enhanced cell death of EBV-positive AGS/BX1 cells when compared with that of EBV-negative AGS cells, possibly related to cell cycle arrest at G2/M phase. Furthermore, SAHA effected strong induction of EBV lytic cycle in nasopharyngeal carcinoma but not in NK lymphoma cells (both expressing EBV latency II pattern), indicating preferential viral lytic induction in epithelial rather than lymphoid malignancies. In conclusion, SAHA is found to be a potent EBV lytic cycle inducing agent, which warrants further investigation into its potential application as a novel virus-targeted drug for treatment of EBV-associated epithelial malignancies.
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Affiliation(s)
- K F Hui
- Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China
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Majerciak V, Kruhlak M, Dagur PK, McCoy JP, Zheng ZM. Caspase-7 cleavage of Kaposi sarcoma-associated herpesvirus ORF57 confers a cellular function against viral lytic gene expression. J Biol Chem 2010; 285:11297-307. [PMID: 20159985 DOI: 10.1074/jbc.m109.068221] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) ORF57 is a viral early protein essential for KSHV multiplication. We found that B cells derived from cavity-based B cell lymphoma with lytic KSHV infection display activation of caspase-8 and cleavage of ORF57 in the cytoplasm by caspase-7 at the aspartate residue at position 33 from the N terminus. Caspase-7 cleavage of ORF57 is prevented by pan-caspase inhibitor z-VAD, caspase-3 and caspase-7 inhibitor z-DEVD, and caspase-7 small interfering RNAs. The caspase-7 cleavage site (30)DETD(33) in ORF57 is not cleavable by caspase-3, although both enzymes use DEXD as a common cleavage site. B cells with lytic KSHV infection and caspase-7 activation exhibited a greatly reduced level of ORF57. A majority of the cells expressing active caspase-7 appeared to have no detectable ORF57 and vice versa. Upon cleavage with caspase-7, ORF57 was deficient in promoting the expression of viral lytic genes. Inhibiting caspase-7 cleavage of ORF57 in KSHV(+) BCBL-1 cells by z-VAD, z-DEVD, or caspase-7 small interfering RNA led to increased expression of viral lytic genes and production of cell-free virus particles. Collectively, our data provide the first compelling evidence that caspase cleavage of ORF57 may represent a cellular function against lytic KSHV infection.
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Affiliation(s)
- Vladimir Majerciak
- HIV and AIDS Malignancy Branch, National Institutes of Health, Bethesda, Maryland 20892, USA
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Levrero M, Pollicino T, Petersen J, Belloni L, Raimondo G, Dandri M. Control of cccDNA function in hepatitis B virus infection. J Hepatol 2009; 51:581-92. [PMID: 19616338 DOI: 10.1016/j.jhep.2009.05.022] [Citation(s) in RCA: 404] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The template of hepatitis B virus (HBV) transcription, the covalently closed circular DNA (cccDNA), plays a key role in the life cycle of the virus and permits the persistence of infection. Novel molecular techniques have opened new possibilities to investigate the organization and the activity of the cccDNA minichromosome in vivo, and recent advances have started to shed light on the complexity of the mechanisms controlling cccDNA function. Nuclear cccDNA accumulates in hepatocyte nuclei as a stable minichromosome organized by histone and non-histone viral and cellular proteins. Identification of the molecular mechanisms regulating cccDNA stability and its transcriptional activity at the RNA, DNA and epigenetic levels in the course of chronic hepatitis B (CH-B) infection may reveal new potential therapeutic targets for anti-HBV drugs and hence assist in the design of strategies aimed at silencing and eventually depleting the cccDNA reservoir.
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Affiliation(s)
- Massimo Levrero
- Department of Internal Medicine, Sapienza University of Rome, Policlinico Umberto I, 0061 Rome, Italy.
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Abstract
Kaposi sarcoma (KS) occurs as a result of Kaposi sarcoma-associated herpesvirus (KSHV) infection, typically in the context of one of several immunodeficient states. In the US, patients with KS may either be co-infected with HIV or receiving immunosuppressant therapy following solid-organ transplantation. Systemic treatment of KS has traditionally involved one of several chemotherapeutic agents administered either in combination or as single agents, which typically provide reasonable response rates and short-term control. However, recurrence of KS is common, and progression-free intervals are under 1 year. For these reasons, new therapies have been sought and with the elucidation of novel pathogenic mechanisms of KS infection, rational therapeutic targets have been identified. These include KSHV replication, restoration of immune competence, and signal transduction pathways utilized by KSHV in the propagation of KS. This review focuses on these emerging targets in the treatment of patients with KS and also highlights important clinicopathologic characteristics.
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Affiliation(s)
- Ryan J Sullivan
- Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
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Affiliation(s)
- Levi E Fried
- Department of Dermatology, Emory University School of Medicine, WMB 5309, 101 Woodruff Circle Atlanta, GA 30322, USA
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Arav-Boger R. Treatment for Kaposi sarcoma herpesvirus: great challenges with promising accomplishments. Virus Genes 2009; 38:195-203. [DOI: 10.1007/s11262-008-0325-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Accepted: 12/30/2008] [Indexed: 01/28/2023]
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Majerciak V, Zheng ZM. Kaposi's sarcoma-associated herpesvirus ORF57 in viral RNA processing. FRONT BIOSCI-LANDMRK 2009; 14:1516-28. [PMID: 19273144 DOI: 10.2741/3322] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 (MTA, mRNA transcript accumulation) is a multifunctional regulator of the expression of viral lytic genes. KSHV ORF57 is expressed during viral lytic infection and is essential for virus production. Like its homologues in the herpesvirus family, ORF57 promotes the accumulation (stabilization) and export of viral intronless RNA transcripts by a mechanism which remains to be defined. The ORF57-Aly/REF interaction plays only a small role in viral RNA export. Although other members of the family generally inhibit the splicing of cellular RNAs, KSHV ORF57 and EBV EB2, in sharp contrast, stimulate viral RNA splicing for the expression of viral intron-containing genes. The functions of KSHV ORF57 are independent of transcription and of other viral proteins; instead, these functions always rely on cellular components and occur in various protein-RNA complexes. ORF57 may synergize with KSHV ORF50 to transactivate a subset of viral promoters by an unknown mechanism. Thus, some functions of ORF57 have been conserved while others have diverged from its homologues as ORF57 adapted over evolution to KSHV biology and pathogenesis.
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Affiliation(s)
- Vladimir Majerciak
- HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-1868, USA
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41
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Abstract
The temporal regulation of DNA replication is thought to be important for chromosome organization and genome stability. We show here that Epstein-Barr virus (EBV) genomes replicate in mid- to late S phase and that agents that accelerate replication timing of EBV reduce viral genome stability. Hydroxyurea (HU) treatment, which is known to eliminate EBV episomes, shifted EBV replication to earlier times in the cell cycle. HU treatment correlated with hyperacetylation of histone H3 and loss of telomere repeat factor 2 (TRF2) binding at the EBV origin of plasmid replication (OriP). Deletion of TRF2 binding sites within OriP or short hairpin RNA depletion of TRF2 advanced the replication timing of OriP-containing plasmids. Inhibitors of class I histone deacetylases (HDACs) increased histone acetylation at OriP, advanced the replication timing of EBV, and reduced EBV genome copy number. We also show that HDAC1 and -2 form a stable complex with TRF2 at OriP and that HU treatment inhibits HDAC activity. We propose that the TRF2-HDAC complex enhances EBV episome stability by providing a checkpoint that delays replication initiation at OriP.
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Casper C. New approaches to the treatment of human herpesvirus 8-associated disease. Rev Med Virol 2008; 18:321-9. [PMID: 18615774 DOI: 10.1002/rmv.583] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Human herpesvirus 8 (HHV-8, also known as Kaposi sarcoma-associated herpesvirus or KSHV) is the etiologic agent of Kaposi sarcoma (KS) and primary effusion lymphoma (PEL), as well as many cases of Castleman disease. Despite significant advances in understanding the biology and natural history of these diseases, current treatment options have important limitations, and strategies to prevent their development in high-risk individuals are lacking. This article reviews the scope of HHV-8-associated disease, as well as the efficacy of current treatment options. Finally, novel approaches to treatment and prevention are described, including antiviral agents, targeted molecular therapy and a combination of these modalities.
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Affiliation(s)
- Corey Casper
- Vaccine and Infectious Disease Institute, Fred Hutchinson Cancer Research Center, and the Department of Medicine, University of Washington, Seattle, Washington 98109, USA.
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Siddiqi T, Joyce RM. A Case of HIV-Negative Primary Effusion Lymphoma Treated with Bortezomib, Pegylated Liposomal Doxorubicin, and Rituximab. ACTA ACUST UNITED AC 2008; 8:300-4. [DOI: 10.3816/clm.2008.n.042] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Cho HJ, Yu F, Sun R, Lee D, Song MJ. Lytic induction of Kaposi's sarcoma-associated herpesvirus in primary effusion lymphoma cells with natural products identified by a cell-based fluorescence moderate-throughput screening. Arch Virol 2008; 153:1517-25. [PMID: 18607675 DOI: 10.1007/s00705-008-0144-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Accepted: 05/28/2008] [Indexed: 11/30/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) has been linked to Kaposi's sarcoma primary effusion lymphoma (PEL), and multicentric Castleman's disease. Intentional lytic induction of gammaherpesviruses in the presence of antiviral drugs is thought to be an effective treatment option for gammaherpesvirus-related tumors. In this study, we used a cell-based fluorescence bioassay system in which a KSHV-infected PEL cell line was stably transfected with a potent viral-promoter-driven reporter gene to identify effective non-toxic reagents capable of inducing latent KSHV. Among 400 plant extracts screened, three extracts increased reporter gene expression in a dose-dependent manner. Furthermore, the three extracts activated the RTA promoter and induced expression of lytic genes in the endogenous viral genomes of KSHV-infected tumor cells. Together, our results demonstrate the effectiveness of a moderate-throughput screening system to identify natural products capable of inducing KSHV reactivation, thereby facilitating the development of novel therapeutic agents for KSHV-associated malignancies.
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Affiliation(s)
- Hye-Jeong Cho
- Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
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Kaposi's sarcoma-associated herpesvirus ORF57 functions as a viral splicing factor and promotes expression of intron-containing viral lytic genes in spliceosome-mediated RNA splicing. J Virol 2008; 82:2792-801. [PMID: 18184716 DOI: 10.1128/jvi.01856-07] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 facilitates the expression of both intronless viral ORF59 genes and intron-containing viral K8 and K8.1 genes (V. Majerciak, N. Pripuzova, J. P. McCoy, S. J. Gao, and Z. M. Zheng, J. Virol. 81:1062-1071, 2007). In this study, we showed that disruption of ORF57 in a KSHV genome led to increased accumulation of ORF50 and K8 pre-mRNAs and reduced expression of ORF50 and K-bZIP proteins but had no effect on latency-associated nuclear antigen (LANA). Cotransfection of ORF57 and K8beta cDNA, which retains a suboptimal intron of K8 pre-mRNA due to alternative splicing, promoted RNA splicing of K8beta and production of K8alpha (K-bZIP). Although Epstein-Barr virus EB2, a closely related homolog of ORF57, had a similar activity in the cotransfection assays, herpes simplex virus type 1 ICP27 was inactive. This enhancement of RNA splicing by ORF57 correlates with the intact N-terminal nuclear localization signal motifs of ORF57 and takes place in the absence of other viral proteins. In activated KSHV-infected B cells, KSHV ORF57 partially colocalizes with splicing factors in nuclear speckles and assembles into spliceosomal complexes in association with low-abundance viral ORF50 and K8 pre-mRNAs and essential splicing components. The association of ORF57 with snRNAs occurs by ORF57-Sm protein interaction. We also found that ORF57 binds K8beta pre-mRNAs in vitro in the presence of nuclear extracts. Collectively our data indicate that KSHV ORF57 functions as a novel splicing factor in the spliceosome-mediated splicing of viral RNA transcripts.
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Alonso PE, Rioja LF, Pera C. Keloids: A viral hypothesis. Med Hypotheses 2008; 70:156-66. [PMID: 17509771 DOI: 10.1016/j.mehy.2007.03.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Accepted: 03/20/2007] [Indexed: 11/30/2022]
Abstract
The triggering cause of keloid formation on a healing wound remains an enigma. In fact, the hypotheses put forward so far to explain this phenomenon seem inconsistent with some clinical features of the disease. The recently established bonds between infectious agents and some pathologies of unknown origin such as peptic ulcer disease, Kaposi's sarcoma or cervical cancer among others led us to consider a potential infectious origin for keloids. This paper presents an infection-based hypothesis (specifically, a viral hypothesis) intended to account for most of their clinical features. Essentially, we hypothesize that healthy individuals carrying a virus, whether known or unknown, associated to some adjuvant, and having some genetic susceptibility, may develop keloids during the scar maturation process in the following manner: the virus would make the bone marrow or lymphatic system its reservoir, residing there in a silent state, and reach the wound via two different mechanisms. The primary mechanism might use an internal circuit through which the viral genome would be transported from its myeloid reservoir to the wound via bone marrow or circulating fibrocytes chemotactically attracted to the damaged skin region. The secondary mechanism might involve an external circuit by which infecting virions via saliva would be shed in the wound directly (preferentially in the sternal or deltoid region) or indirectly (other satellite regions) via the hands or some fomites. A combination of both mechanisms might also be possible. Once in the wound, the virus would switch from a silent state to a latent state by effect of some chemical stimulus probably generated during the tissue repair process; in the new state, the transcription of some of the powerful viral proteins might cause thorough derailment of the normal repair process. As a result, keloid growth might depend both on individual susceptibility and on the viral load deposited into the wound; the greater the susceptibility and viral load were, the more markedly the keloid would develop and the more aggressive it would be.
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Affiliation(s)
- Pedro E Alonso
- Plastic Surgery Unit, Hospital USP Marbella, Avda. Severo Ochoa, 22, Marbella, Málaga, Spain.
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Abstract
Primary effusion lymphoma (PEL) is a rare HIV-associated non-Hodgkin's lymphoma (NHL) that accounts for approximately 4% of all HIV-associated NHL. PEL has a unique clinical presentation in having a predilection for arising in body cavities such as the pleural space, pericardium, and peritoneum. PEL cells are morphologically variable with a null lymphocyte immunophenotype and evidence of human herpesvirus (HHV)-8 infection. The exact oncogenic mechanisms of HHV-8 have not been clearly defined. Treatment is usually with combination CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy and antiretroviral therapy (if HIV positive). The prognosis for PEL is poor, with a median survival time of around 6 months. As the exact molecular steps in HHV-8-driven oncogenesis are unraveled, it is hoped that more specific therapeutic targets will be revealed.
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Affiliation(s)
- Yi-Bin Chen
- Dana-Faber Cancer Institute, Boston, Massachusetts, USA
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Feng WH, Kenney SC. Valproic acid enhances the efficacy of chemotherapy in EBV-positive tumors by increasing lytic viral gene expression. Cancer Res 2007; 66:8762-9. [PMID: 16951192 DOI: 10.1158/0008-5472.can-06-1006] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
EBV infection in tumor cells is generally restricted to the latent forms of viral infection. Switching the latent form of viral infection into the lytic form may induce tumor cell death. We have previously reported that certain chemotherapy agents can increase the amount of lytic viral gene expression in EBV-positive tumor cells. In this report, we have explored the potential utility of valproic acid (VPA), an anti-seizure drug that also has strong histone deacetylase inhibitory activity, for activating lytic viral gene expression in EBV-positive tumors. Although VPA treatment alone induced only a modest increase in the level of lytic viral gene expression, it strongly enhanced the ability of chemotherapeutic agents to induce lytic EBV gene expression in EBV-positive epithelial and lymphoid cells in vitro. Furthermore, VPA enhanced cell killing in vitro by chemotherapeutic agents in lymphoblastoid cells and gastric cells (AGS) containing wild-type EBV. In contrast, VPA did not enhance the cytotoxicity of chemotherapy in lymphoblastoid cells containing a lytic-defective (BZLF1-knockout) form of EBV or in EBV-negative AGS cells. Finally, we found that the combination of VPA and chemotherapy was significantly more effective in inhibiting EBV-driven lymphoproliferative disease in severe combined immunodeficient mice than chemotherapy alone. These results suggest that VPA could potentiate the efficacy of chemotherapy for EBV-positive tumors in patients.
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Affiliation(s)
- Wen-Hai Feng
- Department of Medicine and Microbiology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Kepler GM, Nguyen HK, Webster-Cyriaque J, Banks HT. A dynamic model for induced reactivation of latent virus. J Theor Biol 2007; 244:451-62. [PMID: 17045614 PMCID: PMC2075089 DOI: 10.1016/j.jtbi.2006.08.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 08/08/2006] [Accepted: 08/14/2006] [Indexed: 01/05/2023]
Abstract
We develop a deterministic mathematical model to describe reactivation of latent virus by chemical inducers. This model is applied to the reactivation of latent KSHV in BCBL-1 cell cultures with butyrate as the inducing agent. Parameters for the model are first estimated from known properties of the exponentially growing, uninduced cell cultures. Additional parameters that are necessary to describe induction are determined from fits to experimental data from the literature. Our initial model provides good agreement with two independent sets of experimental data, but also points to the need for a new class of experiments which are required for further understanding of the underlying mechanisms.
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Affiliation(s)
- G M Kepler
- Center for Research in Scientific Computation, North Carolina State University, Raleigh, NC 27695-8205, USA.
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Flanagan JM. Host epigenetic modifications by oncogenic viruses. Br J Cancer 2007; 96:183-8. [PMID: 17179991 PMCID: PMC2359987 DOI: 10.1038/sj.bjc.6603516] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Revised: 11/06/2006] [Accepted: 11/09/2006] [Indexed: 12/29/2022] Open
Abstract
Epigenetic alterations represent an important step in the initiation and progression of most human cancers, but it is difficult to differentiate the early cancer causing alterations from later consequences. Oncogenic viruses can induce transformation via expression of only a small number of viral genes. Therefore, the mechanisms by which oncogenic viruses cause cancer may provide clues as to which epigenetic alterations are critical in early carcinogenesis.
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Affiliation(s)
- J M Flanagan
- CR-UK Viral Oncology Group, Wolfson Institute for Biomedical Research, Gower Street, University College London, London WC1E 6BT, UK.
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