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Vaughan J, Patel M, Suchard M, Gededzha M, Ranchod H, Howard W, Snyman T, Wiggill T. Derangements of immunological proteins in HIV-associated diffuse large B-cell lymphoma: the frequency and prognostic impact. Front Cell Infect Microbiol 2024; 14:1340096. [PMID: 38633747 PMCID: PMC11021765 DOI: 10.3389/fcimb.2024.1340096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 03/12/2024] [Indexed: 04/19/2024] Open
Abstract
Introduction Diffuse large B-cell lymphoma (DLBCL) is an aggressive malignancy of B-cells frequently encountered among people living with HIV. Immunological abnormalities are common in immunocompetent individuals with DLBCL, and are often associated with poorer outcomes. Currently, data on derangements of immunological proteins, such as cytokines and acute phase reactants, and their impact on outcomes in HIV-associated DLBCL (HIV-DLBCL) is lacking. This study assessed the levels and prognostic relevance of interleukin (IL)-6, IL-10 and Transforming Growth Factor Beta (TGFβ), the acute phase proteins C-reactive protein (CRP) and ferritin; serum free light chains (SFLC) (elevation of which reflects a prolonged pro-inflammatory state); and the activity of the immunosuppressive enzyme Indoleamine 2,3-dioxygenase (IDO)in South African patients with DLBCL. Methods Seventy-six patients with incident DLBCL were enrolled, and peripheral blood IL-6, IL-10, TGFβ, SFLC and IDO-activity measured in selected patients. Additional clinical and laboratory findings (including ferritin and CRP) were recorded from the hospital records. Results Sixty-one (80.3%) of the included patients were people living with HIV (median CD4-count = 148 cells/ul), and survival rates were poor (12-month survival rate 30.0%). The majority of the immunological proteins, except for TGFβ and ferritin, were significantly higher among the people living with HIV. Elevation of IL-6, SFLC and IDO-activity were not associated with survival in HIV-DLBCL, while raised IL-10, CRP, ferritin and TGFβ were. On multivariate analysis, immunological proteins associated with survival independently from the International Prognostic Index (IPI) included TGFβ, ferritin and IL-10. Conclusion Derangements of immunological proteins are common in HIV-DLBCL, and have a differential association with survival compared to that reported elsewhere. Elevation of TGFβ, IL-10 and ferritin were associated with survival independently from the IPI. In view of the poor survival rates in this cohort, investigation of the directed targeting of these cytokines would be of interest in our setting.
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Affiliation(s)
- Jenifer Vaughan
- Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- National Health Laboratory Services, Johannesburg, South Africa
| | - Moosa Patel
- Department of Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Clinical Haematology Unit, Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa
| | - Melinda Suchard
- Department of Chemical Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Maemu Gededzha
- National Health Laboratory Services, Johannesburg, South Africa
- Department of Immunology, University of the Witwatersrand, Johannesburg, South Africa
| | - Heena Ranchod
- Department of Chemical Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- National Institute for Communicable Diseases, Centre for Vaccines and Immunology, Johannesburg, South Africa
| | - Wayne Howard
- Department of Chemical Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- National Institute for Communicable Diseases, Centre for Vaccines and Immunology, Johannesburg, South Africa
| | - Tracy Snyman
- National Health Laboratory Services, Johannesburg, South Africa
| | - Tracey Wiggill
- Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- National Health Laboratory Services, Johannesburg, South Africa
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Zhao B, Yin J, Ding L, Luo J, Luo J, Mu J, Pan S, Du J, Zhong Y, Zhang L, Liu L. SPAG6 regulates cell proliferation and apoptosis via TGF-β/Smad signal pathway in adult B-cell acute lymphoblastic leukemia. Int J Hematol 2024; 119:119-129. [PMID: 38147275 DOI: 10.1007/s12185-023-03684-x] [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: 03/10/2023] [Revised: 11/09/2023] [Accepted: 11/17/2023] [Indexed: 12/27/2023]
Abstract
Adult B-cell acute lymphoblastic leukemia (B-ALL) prognosis remains unsatisfactory, and searching for new therapeutic targets is crucial for improving patient prognosis. Sperm-associated antigen 6 (SPAG6), a member of the cancer-testis antigen family, plays an important role in tumors, especially hematologic tumors; however, it is unknown whether SPAG6 plays a role in adult B-ALL. In this study, we demonstrated for the first time that SPAG6 expression was up-regulated in the bone marrow of adult B-ALL patients compared to healthy donors, and expression was significantly reduced in patients who achieved complete remission (CR) after treatment. In addition, patients with high SPAG6 expression were older (≥ 35 years; P = 0.015), had elevated white blood cell counts (WBC > 30 × 109/L; P = 0.021), and a low rate of CR (P = 0.036). We explored the SPAG6 effect on cell function by lentiviral transfection of adult B-ALL cell lines BALL-1 and NALM-6, and discovered that knocking down SPAG6 significantly inhibited cell proliferation and promoted apoptosis. We identified that SPAG6 knockdown might regulate cell proliferation and apoptosis via the transforming growth factor-β (TGF-β)/Smad signaling pathway.
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Affiliation(s)
- Beibei Zhao
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China
- Laboratory Research Center, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400042, China
| | - Jiaxiu Yin
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China
- Laboratory Research Center, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400042, China
| | - Li Ding
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China
- Laboratory Research Center, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400042, China
- Department of Hematology, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Jie Luo
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China
- Laboratory Research Center, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400042, China
| | - Jing Luo
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China
- Laboratory Research Center, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400042, China
| | - Jiao Mu
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China
- Laboratory Research Center, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400042, China
| | - Shirui Pan
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China
- Laboratory Research Center, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400042, China
| | - Juan Du
- Department of Hematology, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Yirui Zhong
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China
| | - Linyi Zhang
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China
| | - Lin Liu
- Department of Hematology, Chongqing Medical University, Medical College Road, Yuzhong District, Chongqing, China.
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3
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Timmins MA, Ringshausen I. Transforming Growth Factor-Beta Orchestrates Tumour and Bystander Cells in B-Cell Non-Hodgkin Lymphoma. Cancers (Basel) 2022; 14:1772. [PMID: 35406544 PMCID: PMC8996985 DOI: 10.3390/cancers14071772] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 03/23/2022] [Indexed: 12/15/2022] Open
Abstract
Transforming growth factor-beta (TGFB) is a critical regulator of normal haematopoiesis. Dysregulation of the TGFB pathway is associated with numerous haematological malignancies including myelofibrosis, acute myeloid leukaemia, and lymphoid disorders. TGFB has classically been seen as a negative regulator of proliferation in haematopoiesis whilst stimulating differentiation and apoptosis, as required to maintain homeostasis. Tumours frequently develop intrinsic resistant mechanisms to homeostatic TGFB signalling to antagonise its tumour-suppressive functions. Furthermore, elevated levels of TGFB enhance pathogenesis through modulation of the immune system and tumour microenvironment. Here, we review recent advances in the understanding of TGFB signalling in B-cell malignancies with a focus on the tumour microenvironment. Malignant B-cells harbour subtype-specific alterations in TGFB signalling elements including downregulation of surface receptors, modulation of SMAD signalling proteins, as well as genetic and epigenetic aberrations. Microenvironmental TGFB generates a protumoural niche reprogramming stromal, natural killer (NK), and T-cells. Increasingly, evidence points to complex bi-directional cross-talk between cells of the microenvironment and malignant B-cells. A greater understanding of intercellular communication and the context-specific nature of TGFB signalling may provide further insight into disease pathogenesis and future therapeutic strategies.
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Affiliation(s)
- Matthew A. Timmins
- Wellcome Trust/MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 0AH, UK;
- Department of Haematology, Addenbrooke’s Hospital, Cambridge University Hospital, Cambridge CB2 0AH, UK
| | - Ingo Ringshausen
- Wellcome Trust/MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 0AH, UK;
- Department of Haematology, Addenbrooke’s Hospital, Cambridge University Hospital, Cambridge CB2 0AH, UK
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4
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Lago-Docampo M, Tenorio J, Hernández-González I, Pérez-Olivares C, Escribano-Subías P, Pousada G, Baloira A, Arenas M, Lapunzina P, Valverde D. Characterization of rare ABCC8 variants identified in Spanish pulmonary arterial hypertension patients. Sci Rep 2020; 10:15135. [PMID: 32934261 PMCID: PMC7492224 DOI: 10.1038/s41598-020-72089-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 08/25/2020] [Indexed: 02/08/2023] Open
Abstract
Pulmonary Arterial Hypertension (PAH) is a rare and fatal disease where knowledge about its genetic basis continues to increase. In this study, we used targeted panel sequencing in a cohort of 624 adult and pediatric patients from the Spanish PAH registry. We identified 11 rare variants in the ATP-binding Cassette subfamily C member 8 (ABCC8) gene, most of them with splicing alteration predictions. One patient also carried another variant in SMAD1 gene (c.27delinsGTAAAG). We performed an ABCC8 in vitro biochemical analyses using hybrid minigenes to confirm the correct mRNA processing of 3 missense variants (c.211C > T p.His71Tyr, c.298G > A p.Glu100Lys and c.1429G > A p.Val477Met) and the skipping of exon 27 in the novel splicing variant c.3394G > A. Finally, we used structural protein information to further assess the pathogenicity of the variants. The results showed 11 novel changes in ABCC8 and 1 in SMAD1 present in PAH patients. After in silico and in vitro biochemical analyses, we classified 2 as pathogenic (c.3288_3289del and c.3394G > A), 6 as likely pathogenic (c.211C > T, c.1429G > A, c.1643C > T, c.2422C > A, c.2694 + 1G > A, c.3976G > A and SMAD1 c.27delinsGTAAAG) and 3 as Variants of Uncertain Significance (c.298G > A, c.2176G > A and c.3238G > A). In all, we show that coupling in silico tools with in vitro biochemical studies can improve the classification of genetic variants.
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Affiliation(s)
- Mauro Lago-Docampo
- CINBIO, Universidade de Vigo, Vigo, Spain
- Instituto de Investigación Sanitaria Galicia Sur, Hospital Álvaro Cunqueiro, Vigo, Spain
| | - Jair Tenorio
- Instituto de Genética Médica y Molecular (INGEMM), Hospital Universitario La Paz-IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
- ITHACA, European Reference Network on Rare Congenital Malformations and Rare Intellectual Disability, Brussels, Belgium
| | - Ignacio Hernández-González
- Servicio de Cardiología, Hospital Universitario Río Hortega, Valladolid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
- Unidad Multidisciplinar de Hipertensión Pulmonar, Servicio de Cardiología, Hospital Universitario, 12 de Octubre, Madrid, Spain
| | - Carmen Pérez-Olivares
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
- Unidad Multidisciplinar de Hipertensión Pulmonar, Servicio de Cardiología, Hospital Universitario, 12 de Octubre, Madrid, Spain
- Servicio de Cardiología, Hospital 12 de Octubre, Madrid, Spain
| | - Pilar Escribano-Subías
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
- Unidad Multidisciplinar de Hipertensión Pulmonar, Servicio de Cardiología, Hospital Universitario, 12 de Octubre, Madrid, Spain
- Servicio de Cardiología, Hospital 12 de Octubre, Madrid, Spain
| | - Guillermo Pousada
- Instituto de Investigación Sanitaria Galicia Sur, Hospital Álvaro Cunqueiro, Vigo, Spain
| | - Adolfo Baloira
- Servicio de Neumología, Complejo Hospitalario de Pontevedra, Pontevedra, Spain
| | - Miguel Arenas
- CINBIO, Universidade de Vigo, Vigo, Spain
- Instituto de Investigación Sanitaria Galicia Sur, Hospital Álvaro Cunqueiro, Vigo, Spain
| | - Pablo Lapunzina
- Instituto de Genética Médica y Molecular (INGEMM), Hospital Universitario La Paz-IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
- ITHACA, European Reference Network on Rare Congenital Malformations and Rare Intellectual Disability, Brussels, Belgium
| | - Diana Valverde
- CINBIO, Universidade de Vigo, Vigo, Spain.
- Instituto de Investigación Sanitaria Galicia Sur, Hospital Álvaro Cunqueiro, Vigo, Spain.
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Hancock MH, Crawford LB, Pham AH, Mitchell J, Struthers HM, Yurochko AD, Caposio P, Nelson JA. Human Cytomegalovirus miRNAs Regulate TGF-β to Mediate Myelosuppression while Maintaining Viral Latency in CD34 + Hematopoietic Progenitor Cells. Cell Host Microbe 2019; 27:104-114.e4. [PMID: 31866424 DOI: 10.1016/j.chom.2019.11.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/25/2019] [Accepted: 11/22/2019] [Indexed: 02/07/2023]
Abstract
Infection with human cytomegalovirus (HCMV) remains a significant cause of morbidity and mortality following hematopoietic stem cell transplant (HSCT) because of various hematologic problems, including myelosuppression. Here, we demonstrate that latently expressed HCMV miR-US5-2 downregulates the transcriptional repressor NGFI-A binding protein (NAB1) to induce myelosuppression of uninfected CD34+ hematopoietic progenitor cells (HPCs) through an increase in TGF-β production. Infection of HPCs with an HCMVΔmiR-US5-2 mutant resulted in decreased TGF-β expression and restoration of myelopoiesis. In contrast, we show that infected HPCs are refractory to TGF-β signaling as another HCMV miRNA, miR-UL22A, downregulates SMAD3, which is required for maintenance of latency. Our data suggest that latently expressed viral miRNAs manipulate stem cell homeostasis by inducing secretion of TGF-β while protecting infected HPCs from TGF-β-mediated effects on viral latency and reactivation. These observations provide a mechanism through which HCMV induces global myelosuppression following HSCT while maintaining lifelong infection in myeloid lineage cells.
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Affiliation(s)
- Meaghan H Hancock
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Lindsey B Crawford
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Andrew H Pham
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Jennifer Mitchell
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Hillary M Struthers
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Andrew D Yurochko
- Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA
| | - Patrizia Caposio
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Jay A Nelson
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA.
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6
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The Dynamic Roles of TGF-β Signalling in EBV-Associated Cancers. Cancers (Basel) 2018; 10:cancers10080247. [PMID: 30060514 PMCID: PMC6115974 DOI: 10.3390/cancers10080247] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 07/23/2018] [Accepted: 07/25/2018] [Indexed: 02/07/2023] Open
Abstract
The transforming growth factor-β (TGF-β) signalling pathway plays a critical role in carcinogenesis. It has a biphasic action by initially suppressing tumorigenesis but promoting tumour progression in the later stages of disease. Consequently, the functional outcome of TGF-β signalling is strongly context-dependent and is influenced by various factors including cell, tissue and cancer type. Disruption of this pathway can be caused by various means, including genetic and environmental factors. A number of human viruses have been shown to modulate TGF-β signalling during tumorigenesis. In this review, we describe how this pathway is perturbed in Epstein-Barr virus (EBV)-associated cancers and how EBV interferes with TGF-β signal transduction. The role of TGF-β in regulating the EBV life cycle in tumour cells is also discussed.
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7
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Nanbo A, Ohashi M, Yoshiyama H, Ohba Y. The Role of Transforming Growth Factor β in Cell-to-Cell Contact-Mediated Epstein-Barr Virus Transmission. Front Microbiol 2018; 9:984. [PMID: 29867885 PMCID: PMC5962739 DOI: 10.3389/fmicb.2018.00984] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 04/26/2018] [Indexed: 01/01/2023] Open
Abstract
Infection of Epstein–Barr virus (EBV), a ubiquitous human gamma herpesvirus, is closely linked to various lymphoid and epithelial malignancies. Previous studies demonstrated that the efficiency of EBV infection in epithelial cells is significantly enhanced by coculturing them with latently infected B cells relative to cell-free infection, suggesting that cell-to-cell contact-mediated viral transmission is the dominant mode of infection by EBV in epithelial cells. However, a detailed mechanism underlying this process has not been fully understood. In the present study, we assessed the role of transforming growth factor β (TGF-β), which is known to induce EBV's lytic cycle by upregulation of EBV's latent-lytic switch BZLF1 gene. We have found that 5 days of cocultivation facilitated cell-to-cell contact-mediated EBV transmission. Replication of EBV was induced in cocultured B cells both with and without a direct cell contact in a time-dependent manner. Treatment of a blocking antibody for TGF-β suppressed both induction of the lytic cycle in cocultured B cells and subsequent viral transmission. Cocultivation with epithelial cells facilitated expression of TGF-β receptors in B cells and increased their susceptibility to TGF-β. Finally, we confirmed the spontaneous secretion of TGF-β from epithelial cells, which was not affected by cell-contact. In contrast, the extracellular microvesicles, exosomes derived from cocultured cells partly contributed to cell-to-cell contact-mediated viral transmission. Taken together, our findings support a role for TGF-β derived from epithelial cells in efficient viral transmission, which fosters induction of the viral lytic cycle in the donor B cells.
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Affiliation(s)
- Asuka Nanbo
- Department of Cell Physiology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Makoto Ohashi
- Department of Oncology, University of Wisconsin, Madison, WI, United States
| | - Hironori Yoshiyama
- Department of Microbiology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Yusuke Ohba
- Department of Cell Physiology, Faculty and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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Campion EM, Hakimjavadi R, Loughran ST, Phelan S, Smith SM, D'Souza BN, Tierney RJ, Bell AI, Cahill PA, Walls D. Repression of the proapoptotic cellular BIK/NBK gene by Epstein-Barr virus antagonizes transforming growth factor β1-induced B-cell apoptosis. J Virol 2014; 88:5001-13. [PMID: 24554662 PMCID: PMC3993823 DOI: 10.1128/jvi.03642-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 02/13/2014] [Indexed: 01/14/2023] Open
Abstract
UNLABELLED The Epstein-Barr virus (EBV) establishes a lifelong latent infection in humans. EBV infection of primary B cells causes cell activation and proliferation, a process driven by the viral latency III gene expression program, which includes EBV nuclear proteins (EBNAs), latent membrane proteins, and untranslated RNAs, including microRNAs. Some latently infected cells enter the long-lived memory B-cell compartment and express only EBNA1 transiently (Lat I) or no EBV protein at all (Lat 0). Targeting the molecular machinery that controls B-cell fate decisions, including the Bcl-2 family of apoptosis-regulating proteins, is crucial to the EBV cycle of infection. Here, we show that BIK (also known as NBK), which encodes a proapoptotic "sensitizer" protein, is repressed by the EBNA2-driven Lat III program but not the Lat I program. BIK repression occurred soon after infection of primary B cells by EBV but not by a recombinant EBV in which the EBNA2 gene had been knocked out. Ectopic BIK induced apoptosis in Lat III cells by a mechanism dependent on its BH3 domain and the activation of caspases. We show that EBNA2 represses BIK in EBV-negative B-cell lymphoma-derived cell lines and that this host-virus interaction can inhibit the proapoptotic effect of transforming growth factor β1 (TGF-β1), a key physiological mediator of B-cell homeostasis. Reduced levels of TGF-β1-associated regulatory SMAD proteins were bound to the BIK promoter in response to EBV Lat III or ectopic EBNA2. These data are evidence of an additional mechanism used by EBV to promote B-cell survival, namely, the transcriptional repression of the BH3-only sensitizer BIK. IMPORTANCE Over 90% of adult humans are infected with the Epstein-Barr virus (EBV). EBV establishes a lifelong silent infection, with its DNA residing in small numbers of blood B cells that are a reservoir from which low-level virus reactivation and shedding in saliva intermittently occur. Importantly, EBV DNA is found in some B-cell-derived tumors in which viral genes play a key role in tumor cell emergence and progression. Here, we report for the first time that EBV can shut off a B-cell gene called BIK. When activated by a molecular signal called transforming growth factor β1 (TGF-β1), BIK plays an important role in killing unwanted B cells, including those infected by viruses. We describe the key EBV-B-cell molecular interactions that lead to BIK shutoff. These findings further our knowledge of how EBV prevents the death of its host cell during infection. They are also relevant to certain posttransplant lymphomas where unregulated cell growth is caused by EBV genes.
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Affiliation(s)
- Eva M. Campion
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland
| | - Roya Hakimjavadi
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland
| | - Sinéad T. Loughran
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland
| | - Susan Phelan
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland
| | - Sinéad M. Smith
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland
| | - Brendan N. D'Souza
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland
| | - Rosemary J. Tierney
- School of Cancer Sciences, College of Medicine and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Andrew I. Bell
- School of Cancer Sciences, College of Medicine and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Paul A. Cahill
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland
- Vascular Biology Research Group, School of Biotechnology, Dublin City University, Dublin, Ireland
| | - Dermot Walls
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland
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9
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Yang ZZ, Grote DM, Ziesmer SC, Xiu B, Yates NR, Secreto FJ, Hodge LS, Witzig TE, Novak AJ, Ansell SM. Soluble and membrane-bound TGF-β-mediated regulation of intratumoral T cell differentiation and function in B-cell non-Hodgkin lymphoma. PLoS One 2013; 8:e59456. [PMID: 23555036 PMCID: PMC3598706 DOI: 10.1371/journal.pone.0059456] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 02/14/2013] [Indexed: 11/18/2022] Open
Abstract
While the effect of TGF-β on malignant B cells in non-Hodgkin lymphoma (NHL) has been previously evaluated, studies to specifically define the role of TGF-β in tumor immunity in B-cell NHL are limited. We found that soluble TGF-β, secreted by both lymphoma cells and intratumoral T cells, is present in the serum of patients with B-cell NHL. Soluble TGF-β promoted regulatory T (Treg) cells by enhancing expression of Foxp3 in CD4+ T cells and suppressed effector helper T (TH) cells by inhibiting expression of IFN-γ and IL-17. Blockade of the IL-2 signaling pathway diminished the effect of soluble TGF-β on T cell differentiation. Furthermore, we found that membrane-bound TGF-β is expressed specifically on the surface of malignant B cells in B-cell NHL. TGF-β was able to bind to the surface of lymphoma B cells through an interaction with heparan sulfate (HS) but not through the TGF-β receptor. We showed that pretreatment of lymphoma B cells with TGF-β significantly inhibits the proliferation and cytokine production of intratumoral T cells. Taken together, these results suggest that tumor-associated soluble and membrane-bound TGF-β are involved in the regulation of intratumoral T cell differentiation and function in B-cell NHL.
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Affiliation(s)
- Zhi-Zhang Yang
- Division of Hematology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
- * E-mail: (ZZY); (SMA)
| | - Deanna M. Grote
- Division of Hematology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Steven C. Ziesmer
- Division of Hematology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Bing Xiu
- Department of Hematology, Tongji Hospital, Tongji University, Shanghai, China
| | - Nicole R. Yates
- Division of Hematology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Frank J. Secreto
- Division of Hematology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Lucy S. Hodge
- Division of Hematology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Thomas E. Witzig
- Division of Hematology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Anne J. Novak
- Division of Hematology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Stephen M. Ansell
- Division of Hematology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
- * E-mail: (ZZY); (SMA)
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10
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Zhang W, Tsuda M, Yang GX, Tsuneyama K, He XS, Ansari AA, Ridgway WM, Coppel RL, Lian ZX, Leung PS, Gershwin ME. Lymphoma-like T cell infiltration in liver is associated with increased copy number of dominant negative form of TGFβ receptor II. PLoS One 2012; 7:e49413. [PMID: 23145171 PMCID: PMC3492285 DOI: 10.1371/journal.pone.0049413] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 10/10/2012] [Indexed: 01/12/2023] Open
Abstract
Hepatosplenic T cell lymphoma (HSTCL) is a distinct and lethal subtype of peripheral T cell lymphoma with an aggressive course and poor outcome despite multiagent chemotherapy. Contradictory literature, an unknown etiology, and poor response to treatment highlight the need to define the malignant process and identify molecular targets with potential for successful therapeutic interventions. Herein, we report that mice homozygously expressing a dominant negative TGFβRII (dnTGFβRII) under the control of the CD4 promoter spontaneously develop lymphoma-like T cell infiltration involving both spleen and liver. Splenomegaly, hepatomegaly and liver dysfunction were observed in homozygous dnTGFβRII mice between 10 weeks and 10 months of age associated with a predominant infiltration of CD4−CD8−TCRβ+NK1.1+ or CD8+TCRβ+NK1.1− T cell subsets. Notch 1 and c-Myc expression at the mRNA levels were significantly increased and positively correlated with the cell number of lymphoid infiltrates in the liver of dnTGFβRII homozygous compared to hemizygous mice. Further, 2×104 isolated lymphoma-like cells transplant disease by adoptive cell transfers. Collectively, our data demonstrate that increased copy number of dnTGFβRII is critical for development of lymphoma-like T cell infiltration.
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Affiliation(s)
- Weici Zhang
- Division of Rheumatology, Allergy and Clinical Immunology, University of California Davis, Davis, California, United States of America
| | - Masanobu Tsuda
- Division of Rheumatology, Allergy and Clinical Immunology, University of California Davis, Davis, California, United States of America
| | - Guo-Xiang Yang
- Division of Rheumatology, Allergy and Clinical Immunology, University of California Davis, Davis, California, United States of America
| | - Koichi Tsuneyama
- Diagnostic Pathology, Graduate School of Medicine and Pharmaceutical Science, University of Toyama, Toyama, Japan
| | - Xiao-Song He
- Division of Rheumatology, Allergy and Clinical Immunology, University of California Davis, Davis, California, United States of America
| | - Aftab A. Ansari
- Department of Pathology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - William M. Ridgway
- Division of Immunology, Allergy and Rheumatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Ross L. Coppel
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Zhe-Xiong Lian
- Institute of Immunology, Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Patrick S.C. Leung
- Division of Rheumatology, Allergy and Clinical Immunology, University of California Davis, Davis, California, United States of America
| | - M. Eric Gershwin
- Division of Rheumatology, Allergy and Clinical Immunology, University of California Davis, Davis, California, United States of America
- * E-mail:
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11
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Kubiczkova L, Sedlarikova L, Hajek R, Sevcikova S. TGF-β - an excellent servant but a bad master. J Transl Med 2012; 10:183. [PMID: 22943793 PMCID: PMC3494542 DOI: 10.1186/1479-5876-10-183] [Citation(s) in RCA: 351] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 08/28/2012] [Indexed: 12/13/2022] Open
Abstract
The transforming growth factor (TGF-β) family of growth factors controls an immense number of cellular responses and figures prominently in development and homeostasis of most human tissues. Work over the past decades has revealed significant insight into the TGF-β signal transduction network, such as activation of serine/threonine receptors through ligand binding, activation of SMAD proteins through phosphorylation, regulation of target genes expression in association with DNA-binding partners and regulation of SMAD activity and degradation. Disruption of the TGF-β pathway has been implicated in many human diseases, including solid and hematopoietic tumors. As a potent inhibitor of cell proliferation, TGF-β acts as a tumor suppressor; however in tumor cells, TGF-β looses anti-proliferative response and become an oncogenic factor. This article reviews current understanding of TGF-β signaling and different mechanisms that lead to its impairment in various solid tumors and hematological malignancies.
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Affiliation(s)
- Lenka Kubiczkova
- Babak Myeloma Group, Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, 625 00, Czech Republic
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12
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A Kaposi's sarcoma-associated herpesvirus microRNA and its variants target the transforming growth factor β pathway to promote cell survival. J Virol 2012; 86:11698-711. [PMID: 22915806 DOI: 10.1128/jvi.06855-11] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Transforming growth factor β (TGF-β) signaling regulates cell growth and survival. Dysregulation of the TGF-β pathway is common in viral infection and cancer. Latent infection by Kaposi's sarcoma-associated herpesvirus (KSHV) is required for the development of several AIDS-related malignancies, including Kaposi's sarcoma and primary effusion lymphoma (PEL). KSHV encodes more than two dozen microRNAs (miRs) derived from 12 pre-miRs with largely unknown functions. In this study, we show that miR variants processed from pre-miR-K10 are expressed in KSHV-infected PEL cells and endothelial cells, while cellular miR-142-3p and its variant miR-142-3p_-1_5, which share the same seed sequence with miR-K10a_ +1_5, are expressed only in PEL cells and not in uninfected and KSHV-infected TIME cells. KSHV miR-K10 variants inhibit TGF-β signaling by targeting TGF-β type II receptor (TβRII). Computational and reporter mutagenesis analyses identified three functional target sites in the TβRII 3' untranslated region (3'UTR). Expression of miR-K10 variants is sufficient to inhibit TGF-β-induced cell apoptosis. A suppressor of the miRs sensitizes latent KSHV-infected PEL cells to TGF-β and induces apoptosis. These results indicate that miR-K10 variants manipulate the TGF-β pathway to confer cells with resistance to the growth-inhibitory effect of TGF-β. Thus, KSHV miRs might target the tumor-suppressive TGF-β pathway to promote viral latency and contribute to malignant cellular transformation.
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13
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TGF-β-induced apoptosis of B-cell lymphoma Ramos cells through reduction of MS4A1/CD20. Oncogene 2012; 32:2096-106. [PMID: 22665052 DOI: 10.1038/onc.2012.219] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Transforming growth factor-β (TGF-β) exhibits growth inhibitory effects on various types of tumor cells, including B-cell lymphoma cells. In the present study, the role of TGF-β in the survival of Epstein-Barr virus-negative B-cell lymphoma Ramos cells was investigated. As TGF-β-induced apoptosis of Ramos cells in vitro and in vivo, we attempted to identify novel target gene(s) responsible for their survival. Oligonucleotide microarray analysis and chromatin immunoprecipitation revealed that Smad proteins directly regulated the transcription of membrane-spanning 4-domains, subfamily A, member 1 (MS4A1), also known as CD20, in Ramos cells upon TGF-β stimulation. In addition, immunohistochemical analysis using clinical samples from B-cell lymphoma patients showed an inverse correlation between the expression of MS4A1/CD20 and phosphorylation of Smad3. Although knockdown of MS4A1/CD20 in Ramos cells resulted in an increase of apoptotic cells, Ramos cells stably expressing MS4A1/CD20 were resistant to TGF-β-induced apoptosis. This suggests that MS4A1/CD20 is responsible for TGF-β-induced apoptosis of B-cell lymphoma cells. Moreover, downregulation of MS4A1/CD20 by TGF-β attenuated the effects of the monoclonal anti-MS4A1/CD20 antibody, rituximab, on Ramos cells. Our findings suggest that the sensitivity of B-cell lymphoma cells to rituximab may be affected by TGF-β signaling.
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14
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Inhibition of germinal centre apoptotic programmes by epstein-barr virus. Adv Hematol 2011; 2011:829525. [PMID: 22110506 PMCID: PMC3202104 DOI: 10.1155/2011/829525] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 07/26/2011] [Indexed: 01/20/2023] Open
Abstract
To establish a persistent latent infection, Epstein-Barr virus (EBV) faces a challenge in that the virus-infected host cell must transit through the germinal centre reaction. This is a site of B cell differentiation where antibody responses are optimised, and the selection criteria for B cells are stringent. The germinal centre environment is harsh, and the vast majority of B cells here die by apoptosis. Only cells receiving adequate survival signals will differentiate fully to be released into the periphery as long-term memory B cells (the site of persistence). In this review, we detail the apoptotic pathways potentially encountered by EBV-infected B cells during the process of infection, and we describe the functions of those EBV-regulated cellular and viral genes that help promote survival of the host B cell.
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Iempridee T, Das S, Xu I, Mertz JE. Transforming growth factor beta-induced reactivation of Epstein-Barr virus involves multiple Smad-binding elements cooperatively activating expression of the latent-lytic switch BZLF1 gene. J Virol 2011; 85:7836-48. [PMID: 21593157 PMCID: PMC3147924 DOI: 10.1128/jvi.01197-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Transforming growth factor β (TGF-β) physiologically induces Epstein-Barr virus (EBV) lytic infection by activating the expression of EBV's latent-lytic switch BZLF1 gene. Liang et al. (J. Biol. Chem. 277:23345-23357, 2002) previously identified a Smad-binding element (SBE) within the BZLF1 promoter, Zp; however, it accounts for only 20 to 30% of TGF-β-mediated activation of transcription from Zp. Here, we identified additional factors responsible for the rest of this activation. The incubation of EBV-positive MutuI cells with a TGF-β neutralizing antibody or inhibitors of the TGF-β type I receptor (TβRI) or Smad3 eliminated the TGF-β-induced reactivation of EBV. The coexpression of Smad2, Smad3, and Smad4 together with a constitutively active form of TβRI induced 15- to 25-fold transcription from Zp in gastric carcinoma AGS cells. By electrophoretic mobility shift assays, we identified four additional Smad-binding elements, named SBE2 to SBE5. Substitution mutations in individual SBEs reduced Smad-mediated activation of Zp by 20 to 60%; together, these mutations essentially eliminated it. Chromatin immunoprecipitation assays confirmed that Smad4 newly bound the Zp region of the EBV genome following the incubation of MutuI cells with TGF-β. SBE2 overlaps the ZEB-binding ZV silencing element of Zp. Depending upon posttranslational modifications, Smad4 either competed with ZEB1 for binding or formed a complex with ZEB1 on the Zp ZV element in a cell-free assay system. In transiently transfected cells, exogenously expressed ZEB1 inhibited Smad-mediated transcriptional activation from Zp. We conclude that TGF-β induces EBV lytic reactivation via the canonical Smad pathway by activating BZLF1 gene expression through multiple SBEs acting in concert.
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Affiliation(s)
| | | | | | - Janet E. Mertz
- Corresponding author. Mailing address:
McArdle Laboratory for Cancer Research, 1400 University Ave., Madison, WI 53706-1599. Phone:
(608) 262-2383. Fax:
(608) 262-2824. E-mail:
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16
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Activation of the TGF-β/Smad signaling pathway in oncogenic transformation by v-Rel. Virology 2011; 413:60-71. [DOI: 10.1016/j.virol.2011.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 10/11/2010] [Accepted: 02/01/2011] [Indexed: 01/22/2023]
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17
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Chen G, Ghosh P, Longo DL. Distinctive mechanism for sustained TGF-β signaling and growth inhibition: MEK1 activation-dependent stabilization of type II TGF-β receptors. Mol Cancer Res 2010; 9:78-89. [PMID: 21131601 DOI: 10.1158/1541-7786.mcr-10-0216] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
There are multiple mechanisms by which cells evade TGF-β-mediated growth inhibitory effects. In this report, we describe a novel mechanism by which cells become resistant to TGF-β-mediated growth suppression. Although having all the components of the TGF-β signaling pathway, different cell lines, RL, HaCaT, and BJAB, have different sensitivities toward TGF-β-induced growth suppression. The TGF-β resistance of RL, a B-cell lymphoma cell line, was due to ligand-induced downregulation of TGF-β receptor II (TβRII) and only transient TGF-β induced nuclear translocation of Smad2 and Smad3. With low-dose phorbol 12-myristate 13-acetate (PMA) or anti-IgM treatment, TGF-β sensitivity was restored by stabilizing TβRII expression and sustaining TGF-β signaling. The MEK inhibitor, U0126, blocked both PMA- and anti-IgM-induced upregulation of TβRII. In HaCaT and BJAB, two TGF-β-sensitive cell lines, which had higher basal levels of phospho-MEK and TβRII compared with RL, U0126 induced downregulation of TβRII and blocked subsequent TGF-β signaling. Similar results were also obtained with normal B cells, where MEK1 inhibitor downregulated TβRII and subsequent TGF-β signaling. Constitutively active MEK1, but not constitutively active ERK2, induced upregulation of TβRII. Furthermore, TβRII physically interacted with the constitutively active MEK1, but not with wild-type MEK1, indicating involvement of active MEK1 in stabilizing TβRII. Collectively, our data suggest a novel mechanism for MEK1 in regulating the sensitivity to TGF-β signaling by stabilizing TβRII.
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Affiliation(s)
- Gang Chen
- Lymphocyte Cell Biology Section, Laboratory of Immunology, Biomedical Research Center, National Institute on Aging, National Institutes of Health, 251 Bayview Blvd., Baltimore, MD 21224, USA
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18
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Bakkebø M, Huse K, Hilden VI, Smeland EB, Oksvold MP. TGF-β-induced growth inhibition in B-cell lymphoma correlates with Smad1/5 signalling and constitutively active p38 MAPK. BMC Immunol 2010; 11:57. [PMID: 21092277 PMCID: PMC3006362 DOI: 10.1186/1471-2172-11-57] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Accepted: 11/23/2010] [Indexed: 11/29/2022] Open
Abstract
Background Cytokines of the transforming growth factor β (TGF-β) superfamily exert effects on proliferation, apoptosis and differentiation in various cell types. Cancer cells frequently acquire resistance to the anti-proliferative signals of TGF-β, which can be due to mutations in proteins of the signalling cascade. We compared the TGF-β-related signalling properties in B-cell lymphoma cell lines that were sensitive or resistant to TGF-β-induced anti-proliferative effects. Results TGF-β sensitive cell lines expressed higher cell surface levels of the activin receptor-like kinase 5 (Alk-5), a TGF-β receptor type 1. The expression levels of the other TGF-β and bone morphogenetic protein receptors were comparable in the different cell lines. TGF-β-induced phosphorylation of Smad2 was similar in TGF-β sensitive and resistant cell lines. In contrast, activation of Smad1/5 was restricted to cells that were sensitive to growth inhibition by TGF-β. Moreover, with activin A we detected limited anti-proliferative effects, strong phosphorylation of Smad2, but no Smad1/5 phosphorylation. Up-regulation of the TGF-β target genes Id1 and Pai-1 was identified in the TGF-β sensitive cell lines. Constitutive phosphorylation of MAPK p38 was restricted to the TGF-β sensitive cell lines. Inhibition of p38 MAPK led to reduced sensitivity to TGF-β. Conclusions We suggest that phosphorylation of Smad1/5 is important for the anti-proliferative effects of TGF-β in B-cell lymphoma. Alk-5 was highly expressed in the sensitive cell lines, and might be important for signalling through Smad1/5. Our results indicate a role for p38 MAPK in the regulation of TGF-β-induced anti-proliferative effects.
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Affiliation(s)
- Maren Bakkebø
- Department of Immunology, Institute for Cancer Research, Oslo University Hospital Montebello, Oslo, Norway
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19
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MicroRNA miR-155 inhibits bone morphogenetic protein (BMP) signaling and BMP-mediated Epstein-Barr virus reactivation. J Virol 2010; 84:6318-27. [PMID: 20427544 DOI: 10.1128/jvi.00635-10] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
MicroRNA miR-155 is expressed at elevated levels in human cancers including cancers of the lung, breast, colon, and a subset of lymphoid malignancies. In B cells, miR-155 is induced by the oncogenic latency gene expression program of the human herpesvirus Epstein-Barr virus (EBV). Two other oncogenic herpesviruses, Kaposi's sarcoma-associated herpesvirus and Marek's disease virus, encode functional homologues of miR-155, suggesting a role for this microRNA in the biology and pathogenesis of these viruses. Bone morphogenetic protein (BMP) signaling is involved in an array of cellular processes, including differentiation, growth inhibition, and senescence, through context-dependent interactions with multiple signaling pathways. Alteration of this pathway contributes to a number of disease states including cancer. Here, we show that miR-155 targets the 3' untranslated region of multiple components of the BMP signaling cascade, including SMAD1, SMAD5, HIVEP2, CEBPB, RUNX2, and MYO10. Targeting of these mediators results in the inhibition of BMP2-, BMP6-, and BMP7-induced ID3 expression as well as BMP-mediated EBV reactivation in the EBV-positive B-cell line, Mutu I. Further, miR-155 inhibits SMAD1 and SMAD5 expression in the lung epithelial cell line A549, it inhibits BMP-mediated induction of the cyclin-dependent kinase inhibitor p21, and it reverses BMP-mediated cell growth inhibition. These results suggest a role for miR-155 in controlling BMP-mediated cellular processes, in regulating BMP-induced EBV reactivation, and in the inhibition of antitumor effects of BMP signaling in normal and virus-infected cells.
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20
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Paschos K, Smith P, Anderton E, Middeldorp JM, White RE, Allday MJ. Epstein-barr virus latency in B cells leads to epigenetic repression and CpG methylation of the tumour suppressor gene Bim. PLoS Pathog 2009; 5:e1000492. [PMID: 19557159 PMCID: PMC2695769 DOI: 10.1371/journal.ppat.1000492] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 05/28/2009] [Indexed: 12/31/2022] Open
Abstract
In human B cells infected with Epstein-Barr virus (EBV), latency-associated virus gene products inhibit expression of the pro-apoptotic Bcl-2-family member Bim and enhance cell survival. This involves the activities of the EBV nuclear proteins EBNA3A and EBNA3C and appears to be predominantly directed at regulating Bim mRNA synthesis, although post-transcriptional regulation of Bim has been reported. Here we show that protein and RNA stability make little or no contribution to the EBV-associated repression of Bim in latently infected B cells. However, treatment of cells with inhibitors of histone deacetylase (HDAC) and DNA methyltransferase (DNMT) enzymes indicated that epigenetic mechanisms are involved in the down-regulation of Bim. This was initially confirmed by chromatin immunoprecipitation analysis of histone acetylation levels on the Bim promoter. Consistent with this, methylation-specific PCR (MSP) and bisulphite sequencing of regions within the large CpG island located at the 5′ end of Bim revealed significant methylation of CpG dinucleotides in all EBV-positive, but not EBV-negative B cells examined. Genomic DNA samples exhibiting methylation of the Bim promoter included extracts from a series of explanted EBV-positive Burkitt's lymphoma (BL) biopsies. Subsequent analyses of the histone modification H3K27-Me3 (trimethylation of histone H3 lysine 27) and CpG methylation at loci throughout the Bim promoter suggest that in EBV-positive B cells repression of Bim is initially associated with this repressive epigenetic histone mark gradually followed by DNA methylation at CpG dinucleotides. We conclude that latent EBV initiates a chain of events that leads to epigenetic repression of the tumour suppressor gene Bim in infected B cells and their progeny. This reprogramming of B cells could have important implications for our understanding of EBV persistence and the pathogenesis of EBV-associated disease, in particular BL. Bim is a cellular inducer of programmed cell death (pcd), so the level of Bim is a critical regulator of lymphocyte survival and reduced expression enhances lymphomagenesis in mice and humans. Regulation of Bim is uniquely important in the pathogenesis of Burkitt's lymphoma (BL), since in this human childhood cancer the Myc gene is deregulated by chromosomal translocation and Myc can induce pcd via Bim. Latent EBV represses Bim expression, and here we have discovered that this involves mechanisms that reprogramme B cells and their progeny. EBV does not significantly alter Bim protein or RNA stability, but relief of EBV-mediated repression by specific inhibitors suggested it involves modifications to chromatin. Consistent with this, reduced histone acetylation and increased levels of DNA methylation on the Bim promoter were found after latent EBV infection. Further analysis suggested that the DNA methylation is preceded by repression mediated via a polycomb protein repressive complex targeting the Bim gene. By initiating the heritable suppression of Bim, EBV increases the likelihood of B lymphomagenesis in general and BL in particular. This reprogramming of B cells by EBV may also play a role in the development of other chronic disorders such as autoimmune disease and suggests a general mechanism that could contribute to the pathogenesis associated with other microorganisms.
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Affiliation(s)
- Kostas Paschos
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Paul Smith
- Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom
| | - Emma Anderton
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Jaap M. Middeldorp
- Department of Pathology, VU University Medical Centre, Amsterdam, The Netherlands
| | - Robert E. White
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Martin J. Allday
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
- * E-mail:
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21
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Acute and chronic in vivo therapeutic resistance. Biochem Pharmacol 2009; 77:1665-73. [DOI: 10.1016/j.bcp.2009.01.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 01/05/2009] [Accepted: 01/12/2009] [Indexed: 01/03/2023]
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22
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Spender LC, O'Brien DI, Simpson D, Dutt D, Gregory CD, Allday MJ, Clark LJ, Inman GJ. TGF-beta induces apoptosis in human B cells by transcriptional regulation of BIK and BCL-XL. Cell Death Differ 2009; 16:593-602. [PMID: 19136942 PMCID: PMC2857326 DOI: 10.1038/cdd.2008.183] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
TGF-β potently induces apoptosis in Burkitt’s Lymphoma (BL) cell lines and in explanted primary human B lymphocytes. The physiological relevance and mechanism of TGF-β-mediated apoptosis induction in these cells remains to be determined. Here we demonstrate the requirement for TGF-β-mediated regulation of BIK and BCL-XL to activate an intrinsic apoptotic pathway in centroblastic BL cells. TGF-β directly induced transcription of BIK and a consensus Smad binding element identified in the BIK promoter recruits TGF-β-activated Smad transcription factor complexes in vivo. TGF-β also transcriptionally repressed expression of the apoptosis inhibitor BCL-XL. Inhibition of BCL-XL sensitised BL cells to TGF-β-induced apoptosis while overexpression of BCL-XL or suppression of BIK by shRNA, diminished TGF-β-induced apoptosis. BIK and BCL-XL were also identified as TGF-β target genes in purified normal human centroblast B cells and immunohistochemical analyses of tonsil tissue revealed widespread TGF-β receptor-regulated Smad activation and a focal pattern of BIK expression. Furthermore, using a selective inhibitor of the TGF-β receptor we provide evidence that autocrine TGF-β signaling through ALK5 contributes to the default apoptotic program in normal human centroblasts undergoing spontaneous apoptosis. Our data suggests that TGF-β may act as a physiological mediator of human germinal centre homeostasis via regulation of BIK and BCL-XL.
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Affiliation(s)
- L C Spender
- Growth Factor Signalling Laboratory, The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, UK.
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23
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Spender LC, Inman GJ. TGF-beta induces growth arrest in Burkitt lymphoma cells via transcriptional repression of E2F-1. J Biol Chem 2008; 284:1435-42. [PMID: 19022773 DOI: 10.1074/jbc.m808080200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Transforming growth factor-beta (TGF-beta) is a potent regulator of tissue homeostasis and can act as both a tumor suppressor and a tumor promoter. The ability to induce cell cycle arrest is a major component of the tumor suppressor function of TGF-beta. Lung, mammary, and skin epithelial cells exhibit a common minimal cytostatic program in response to TGF-beta signaling involving the repression of the growth-promoting factors c-MYC, Id1, Id2, and Id3. Loss of c-MYC expression is a pivotal event in this process, resulting in derepression of the cyclin-dependent kinase inhibitors CDKN1A (p21) and CDKN2B (p15) and ultimately leading to growth arrest. It is not clear, however, which responses are necessary for TGF-beta-mediated growth arrest in other cell types. Here, in human Burkitt lymphoma cells transformed by deregulated c-MYC expression, we demonstrate that efficient TGF-beta-induced cytostasis can occur despite both maintenance of c-MYC levels and a lack of p21 and p15 induction. TGF-beta treatment also results in induction, rather than repression, of Id1 and Id2 expression. In this context, growth arrest correlates with transcriptional repression of E2F-1, and overexpression of E2F-1 in Burkitt lymphoma cells largely overcomes the TGF-beta-mediated G(1) arrest phenotype. These data indicate that deregulation of c-MYC in lymphoma cells does not overcome the tumor suppressor function of TGF-beta and that repression of E2F-1 transcription is sufficient for the efficient induction of cytostasis.
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Affiliation(s)
- Lindsay C Spender
- Growth Factor Signalling Laboratory, The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD, United Kingdom
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24
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Isufi I, Seetharam M, Zhou L, Sohal D, Opalinska J, Pahanish P, Verma A. Transforming Growth Factor-βSignaling in Normal and Malignant Hematopoiesis. J Interferon Cytokine Res 2007; 27:543-52. [PMID: 17651015 DOI: 10.1089/jir.2007.0009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Transforming growth factor-beta (TGF-beta) is an important physiologic regulator of cell growth and differentiation. TGF-beta has been shown to inhibit the proliferation of quiescent hematopoietic stem cells and stimulate the differentiation of late progenitors to erythroid and myeloid cells. Insensitivity to TGF-beta is implicated in the pathogenesis of many myeloid and lymphoid neoplasms. Loss of extracellular TGF receptors and disruption of intracellular TGF-beta signaling by oncogenes is seen in a variety of malignant and premalignant states. TGF-beta can also affect tumor growth and survival by influencing the secretion of other growth factors and manipulation of the tumor microenvironment. Recent development of small molecule inhibitors of TGF-beta receptors and other signaling intermediaries may allow us to modulate TGF signaling for future therapeutic interventions in cancer.
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Affiliation(s)
- Iris Isufi
- Albert Einstein College of Medicine, Bronx, NY 10461, USA
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25
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Chen G, Ghosh P, Osawa H, Sasaki CY, Rezanka L, Yang J, O'Farrell TJ, Longo DL. Resistance to TGF-beta 1 correlates with aberrant expression of TGF-beta receptor II in human B-cell lymphoma cell lines. Blood 2007; 109:5301-7. [PMID: 17339425 PMCID: PMC1890833 DOI: 10.1182/blood-2006-06-032128] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Resistance to transforming growth factor (TGF)-beta1-mediated growth suppression in tumor cells is often associated with the functional loss of TGF-beta receptors. Here we describe two B-cell lymphoma cell lines (DB and RL) that differ in their sensitivity to TGF-beta1-mediated growth suppression. The TGF-beta1-resistant cell line DB lacked functional TGF-beta receptor II (T beta RII) in contrast to the TGF-beta-responsive cell line RL, whereas both cell lines had comparable levels of receptor I (T beta RI). Lack of functional T beta RII was correlated with the lack of TGF-beta1-induced nuclear translocation of phospho-Smad3 and phospho-Smad2, the lack of nuclear expression of p21(Cip1/WAF1), and the down-regulation of c-Myc in DB cells. Transfection of wild-type, but not a C-terminal-truncated, form of T beta RII rendered the DB cell line responsive to TGF-beta1-mediated growth suppression. Analysis of the T beta RII gene in DB cells revealed the absence of T beta RII message, which was reversed upon 5'-azacytidine treatment, indicating that the promoter methylation might be the cause of gene silencing. Promoter analysis revealed CpG methylations at -25 and -140 that correlated with the gene silencing. These data suggest that promoter methylation plays an important role in T beta RII gene silencing and subsequent development of a TGF-beta1-resistant phenotype by some B-cell lymphoma cells.
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Affiliation(s)
- Gang Chen
- Lymphocyte Cell Biology Unit, Laboratory of Immunology, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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26
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Fukuda M, Kurosaki H, Sairenji T. Loss of functional transforming growth factor (TGF)-beta type II receptor results in insensitivity to TGF-beta1-mediated apoptosis and Epstein-Barr virus reactivation. J Med Virol 2006; 78:1456-64. [PMID: 16998876 DOI: 10.1002/jmv.20719] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Transforming growth factor (TGF)-beta1 induces not only cell growth inhibition or apoptosis but also Epstein-Barr virus (EBV) reactivation in some Burkitt's lymphoma (BL) cell lines. The purpose of this study was to define the role of TGF-beta signaling molecules in response to TGF-beta1-mediated cell growth inhibition, apoptosis, and EBV reactivation in BL cell lines. First, we confirmed the effect of TGF-beta1 on the cell growth and EBV reactivation in six BL cell lines. TGF-beta1 induced cell growth inhibition and EBV reactivation in these cell lines but did not in Akata cells. To elucidate the mechanism of TGF-beta1 unresponsiveness in Akata cells, we studied the expression of TGF-beta receptors and the intracellular signaling molecules Smads. All cell lines expressed TGF-beta type I receptor, Smad2, Smad3, and Smad4. TGF-beta type II receptor (R-II) was expressed in all cell lines except Akata cells. Introduction of the TGF-beta R-II into Akata cells results in sensitivity to TGF-beta1-mediated growth inhibition, apoptosis, and EBV reactivation. In addition, to test a possibility to the transcriptional repression of the TGF-beta R-II gene in Akata cells, the effect of histone deacetylation (HDAC) inhibitor, trichostatin A (TSA) was examined. The expression of TGF-beta R-II in Akata cells was induced by TSA treatment. These results suggest that the lack of functional TGF-beta R-II impedes the progression of signals through TGF-beta1 and becomes a determinant of unresponsiveness to TGF-beta1-mediated growth inhibition and EBV reactivation.
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Affiliation(s)
- Makoto Fukuda
- Division of Biosignaling, Department of Biomedical Sciences, School of Life Science, Faculty of Medicine, Tottori University, Yonago, Japan
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27
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Letterio J, Rudikoff E, Voong N, Bauer SR. Transforming Growth Factor-β1 Sensitivity Is Altered inAbl-Myc- andRaf-Myc-Induced Mouse Pre-B-Cell Tumors. Stem Cells 2006; 24:2611-7. [PMID: 16945999 DOI: 10.1634/stemcells.2005-0623] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Understanding the mechanisms leading to transformation of early B-lineage precursors is an important step leading to rational design of new treatments for precursor (pre)-B-cell leukemia. We used normal mouse pre-B cells to determine if and how transforming growth factor (TGF)-beta1 affects these precursors to the B-cell lineage and whether transformed pre-B cells respond to TGF-beta1. We found that normal pre-B cells proliferating in the presence of interleukin (IL)-7 enter cell-cycle arrest after exposure to TGF-beta1. However, clonally related IL-7-independent tumors induced by oncogenes abl + myc or raf + myc have reduced sensitivity to TGF-beta1. In contrast, tumor cells induced by myc alone remain sensitive to TGF-beta1 growth suppression. These results suggest that lesions in different molecular signaling pathways can lead to loss of TGF-beta1 sensitivity in a single cell type. The approach of using normal pre-B-cell lines and transformation by overexpression of different oncogenes provides a system to compare and contrast molecular pathways that lead to full malignancy.
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Affiliation(s)
- John Letterio
- Case Western Reserve University, Division of Pediatric Hematology/Oncology, The Ireland Cancer Center, Cleveland, Ohio, USA
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28
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Lachanas E, Tomos P, Fotinou M, Miyakis S. Lymphoma presenting as chronic aortic dissection in Marfan syndrome. Ann Hematol 2005; 85:181-2. [PMID: 16328477 DOI: 10.1007/s00277-005-0036-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Accepted: 10/10/2005] [Indexed: 11/25/2022]
MESH Headings
- Adolescent
- Antigens, CD19/metabolism
- Antigens, CD20/metabolism
- Humans
- Ki-67 Antigen/metabolism
- Lymphoma, B-Cell/metabolism
- Lymphoma, B-Cell/pathology
- Lymphoma, B-Cell/surgery
- Lymphoma, Large B-Cell, Diffuse/metabolism
- Lymphoma, Large B-Cell, Diffuse/pathology
- Lymphoma, Large B-Cell, Diffuse/surgery
- Male
- Marfan Syndrome/complications
- Marfan Syndrome/metabolism
- Marfan Syndrome/pathology
- Marfan Syndrome/surgery
- Mediastinal Neoplasms/metabolism
- Mediastinal Neoplasms/pathology
- Mediastinal Neoplasms/surgery
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29
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Seo T, Park J, Choe J. Kaposi's Sarcoma–Associated Herpesvirus Viral IFN Regulatory Factor 1 Inhibits Transforming Growth Factor-β Signaling. Cancer Res 2005; 65:1738-47. [PMID: 15753369 DOI: 10.1158/0008-5472.can-04-2374] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus, also called human herpesvirus 8, has been implicated in the pathogenesis of Kaposi's sarcoma, body cavity-based primary effusion lymphoma, and some forms of multicentric Castleman's disease. The Kaposi's sarcoma-associated herpesvirus open reading frame K9 encodes viral IFN regulatory factor 1 (vIRF1), which functions as a repressor of IFN-mediated signal transduction. vIRF1 expression in NIH 3T3 cells leads to transformation and consequently induces malignant fibrosarcoma in nude mice, suggesting that vIRF1 is a strong oncoprotein. Here, we show that vIRF1 inhibited transforming growth factor-beta (TGF-beta) signaling via its targeting of Smad proteins. vIRF1 suppressed TGF-beta-mediated transcription and growth arrest. vIRF1 directly interacted with both Smad3 and Smad4, resulting in inhibition of their transactivation activity. Studies using vIRF1 deletion mutants showed that the central region of vIRF1 was required for vIRF1 association with Smad3 and Smad4 and that this region was also important for inhibition of TGF-beta signaling. In addition, we found that vIRF1 interfered with Smad3-Smad4 complex formation and inhibited Smad3/Smad4 complexes from binding to DNA. These results indicate that vIRF1 inhibits TGF-beta signaling via interaction with Smads. In addition, the data indicate the TGF-beta pathway is an important target for viral oncoproteins.
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Affiliation(s)
- Taegun Seo
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Korea
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30
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Fukuda M, Longnecker R. Latent membrane protein 2A inhibits transforming growth factor-beta 1-induced apoptosis through the phosphatidylinositol 3-kinase/Akt pathway. J Virol 2004; 78:1697-705. [PMID: 14747535 PMCID: PMC369507 DOI: 10.1128/jvi.78.4.1697-1705.2004] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2003] [Accepted: 10/27/2003] [Indexed: 12/26/2022] Open
Abstract
Latent membrane protein 2A (LMP2A) blocks B-cell receptor signal transduction in vitro by binding the Syk and Lyn protein tyrosine kinases. As well as blocking B-cell signal transduction, LMP2A has been shown to activate the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway, which acts as a survival signal in both B cells and epithelial cells. Transforming growth factor beta 1 (TGF-beta 1) is a multifunctional cytokine that plays important roles in regulating cell growth and differentiation in many biological systems. The loss of the growth-inhibitory response to the TGF-beta 1 signal is found in many cancers and is widely thought to promote tumor development. In this study, we found that LMP2A induced the phosphorylation of Akt (serine 473) in Burkitt's lymphoma cell line Ramos and in gastric carcinoma cell line HSC-39 and partially enhanced cell viability following TGF-beta 1 treatment. In addition, LMP2A partially inhibited TGF-beta 1-induced DNA fragmentation and cleavage of poly(ADP-ribose) polymerase (PARP). In the presence of LY294002, an inhibitor of PI3-K, the LMP2A-mediated inhibitory effects on TGF-beta 1-induced DNA fragmentation and cleavage of PARP were alleviated. Furthermore, LMP2A did not alter the levels of expression of type I and type II TGF-beta 1 receptors. Taken together, these results suggest that LMP2A may inhibit TGF-beta 1-mediated apoptosis through activation of the PI3-K/Akt pathway.
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Affiliation(s)
- Makoto Fukuda
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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31
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Tarakanova VL, Wold WSM. Transforming growth factor beta1 receptor II is downregulated by E1A in adenovirus-infected cells. J Virol 2003; 77:9324-36. [PMID: 12915548 PMCID: PMC187388 DOI: 10.1128/jvi.77.17.9324-9336.2003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Transforming growth factor beta1 (TGF-beta1) signaling is compromised in many tumors, thereby allowing the tumor to escape the growth-inhibitory and proapoptotic activities of the cytokine. Human adenoviruses interfere with a number of cellular pathways involved in cell cycle regulation and apoptosis, initially placing the cell in a "tumor-like" state by forcing quiescent cells into the cell cycle and also inhibiting apoptosis. We report that adenovirus-infected cells resemble tumor cells in that TGF-beta1 signaling is inhibited. The levels of TGF-beta1 receptor II (TbetaRII) in adenovirus-infected cells were decreased, and this decrease was mapped, by using virus mutants, to the E1A gene and to amino acids 2 to 36 and the C-terminal binding protein binding site in the E1A protein. The decrease in the TbetaRII protein was accompanied by a decrease in TbetaRII mRNA. The decrease in TbetaRII protein levels in adenovirus-infected cells was greater than the decrease in TbetaRII mRNA, suggesting that downregulation of the TbetaRII protein may occur through more than one mechanism. Surprisingly in this context, the half-lives of the TbetaRII protein in infected and uninfected cells were similar. TGF-beta1 signaling was compromised in cells infected with wild-type adenovirus, as measured with 3TP-lux, a TGF-beta-sensitive reporter plasmid expressing luciferase. Adenovirus mutants deficient in TbetaRII downregulation did not inhibit TGF-beta1 signaling. TGF-beta1 pretreatment reduced the relative abundance of adenovirus structural proteins in infected cells, an effect that was potentiated when cells were infected with mutants incapable of modulating the TGF-beta signaling pathway. These results raise the possibility that inhibition of TGF-beta signaling by E1A is a means by which adenovirus counters the antiviral defenses of the host.
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Affiliation(s)
- Vera L Tarakanova
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA.
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32
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Kim SJ, Letterio J. Transforming growth factor-beta signaling in normal and malignant hematopoiesis. Leukemia 2003; 17:1731-7. [PMID: 12970772 DOI: 10.1038/sj.leu.2403069] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Transforming growth factor-beta (TGF-beta) is perhaps the most potent endogenous negative regulator of hematopoiesis. The intracellular signaling events mediating the effects of TGF-beta are multiple, involving extensive crosstalk between Smad-dependent and MAP-kinase-dependent pathways. We are only beginning to understand the importance of the balance between these cascades as a determinant of the response to TGF-beta, and have yet to determine the roles that disruption in TGF-beta signaling pathways might play in leukemogenesis. This review summarizes current knowledge regarding the function of TGF-beta in normal and malignant hematopoiesis. The principal observations made by gene targeting studies in mice are reviewed, with an emphasis on how a disruption of this pathway in vivo can affect blood cell development and immune homeostasis. We overview genetic alterations that lead to impaired TGF-beta signaling in hematopoietic neoplasms, including the suppression of Smad-dependent transcriptional responses by oncoproteins such as Tax and Evi-1, and fusion proteins such as AML1/ETO. We also consider mutations in genes encoding components of the core cell cycle machinery, such as p27(Kip1) and p15(INK4A), and emphasize their impact on the ability of TGF-beta to induce G1 arrest. The implications of these observations are discussed, and opinions regarding important directions for future research on TGF-beta in hematopoiesis are provided.
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Affiliation(s)
- S-J Kim
- Laboratory of Cell Regulation and Carcinogenesis, National Cancer Institute, Bethesda, MD 20892, USA
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33
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Maesako Y, Uchiyama T, Ohno H. Comparison of gene expression profiles of lymphoma cell lines from transformed follicular lymphoma, Burkitt's lymphoma and de novo diffuse large B-cell lymphoma. Cancer Sci 2003; 94:774-81. [PMID: 12967475 PMCID: PMC11160262 DOI: 10.1111/j.1349-7006.2003.tb01518.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2003] [Revised: 06/26/2003] [Accepted: 07/07/2003] [Indexed: 11/28/2022] Open
Abstract
To determine the specific gene expression in B-cell lymphoma subtypes, we compared expression profiles of cell lines from transformed follicular lymphoma (tFL), Epstein-Barr virus-negative (EBV(-)) Burkitt's lymphoma (BL) and EBV(+)BL. Complementary DNAs were synthesized from these cell lines and hybridized with the Atlas Human 1.2 Array membrane. Hierarchical clustering analysis based upon the levels of 43 genes highlighted characteristic expression patterns of the 3 lymphoma subtypes. Genes expressed at higher levels in tFL than EBV(-)BL and EBV(+)BL included calcium/calmodulin-dependent protein kinase I (CAMK1) and mitogen-activated protein kinase 10 (MAPK10). EBV(-)BL was characterized by high-level expression of amyloid beta precursor protein (APP), heat shock 27 kD protein 1 (HSPB1) and mothers against decapentaplegic homolog 1 (MADH1). Gardner-Rasheed feline sarcoma viral oncogene homolog (FGR) was the most significant gene to delineate EBV(+)BL. A subtype prediction algorithm using 34 genes correctly classified 22 (92%) of 24 lymphomas into FL/tFL, EBV(-)BL or EBV(+)BL. By comparison with normal reference B-cell materials, the expression patterns of the selected genes were characteristic of lymphomas. We extended the clustering analysis to cell lines from de novo diffuse large B-cell lymphoma (DLBCL). The DLBCL cell lines were either separated from the former 3 lymphoma subtypes or segregated with EBV(+)BL, possibly reflecting variable genetic abnormalities. The associations of CAMK1 with tFL, APP and MADH1 with EBV(-)BL, FGR with EBV(+)BL, and BCL2 with tFL and DLBCL were confirmed by real-time quantitative reverse transcriptase-mediated polymerase chain reaction assays. This study has provided new molecular markers, expressions of which are closely associated with B-cell lymphoma subtypes.
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MESH Headings
- B-Lymphocytes/physiology
- Biomarkers, Tumor/analysis
- Cell Line, Transformed/virology
- Cells, Cultured
- DNA, Complementary/genetics
- Epstein-Barr Virus Infections/virology
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic
- Herpesvirus 4, Human/pathogenicity
- Humans
- Lymphoma, B-Cell/genetics
- Lymphoma, Follicular/genetics
- Lymphoma, Large B-Cell, Diffuse/genetics
- Oligonucleotide Array Sequence Analysis
- RNA, Messenger/analysis
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Affiliation(s)
- Yoshitomo Maesako
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
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34
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Kracklauer MP, Schmidt C, Sclabas GM. TGFbeta1 signaling via alphaVbeta6 integrin. Mol Cancer 2003; 2:28. [PMID: 12935295 PMCID: PMC184456 DOI: 10.1186/1476-4598-2-28] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2003] [Accepted: 08/07/2003] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Transforming growth factor beta1 (TGFbeta1) is a potent inhibitor of epithelial cell growth, thus playing an important role in tissue homeostasis. Most carcinoma cells exhibit a reduced sensitivity for TGFbeta1 mediated growth inhibition, suggesting TGFbeta1 participation in the development of these cancers. The tumor suppressor gene DPC4/SMAD4, which is frequently inactivated in carcinoma cells, has been described as a key player in TGFbeta1 mediated growth inhibition. However, some carcinoma cells lacking functional SMAD4 are sensitive to TGFbeta1 induced growth inhibition, thus requiring a SMAD4 independent TGFbeta1 pathway. RESULTS Here we report that mature TGFbeta1 is a ligand for the integrin alphaVbeta6, independent of the common integrin binding sequence motif RGD. After TGFbeta1 binds to alphaVbeta6 integrin, different signaling proteins are activated in TGFbeta1-sensitive carcinoma cells, but not in cells that are insensitive to TGFbeta1. Among others, interaction of TGFbeta1 with the alphaVbeta6 integrin resulted in an upregulation of the cell cycle inhibitors p21/WAF1 and p27 leading to growth inhibition in SMAD4 deleted as well as in SMAD4 wildtype carcinoma cells. CONCLUSIONS Our data provide support for the existence of an alternate TGFbeta1 signaling pathway that is independent of the known SMAD pathway. This alternate pathway involves alphaVbeta6 integrin and the Ras/MAP kinase pathway and does not employ an RGD motif in TGFbeta1-sensitive tumor cells. The combined action of these two pathways seems to be necessary to elicit a complete TGFbeta1 signal.
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Affiliation(s)
- Martin P Kracklauer
- Section of Molecular Cell and Developmental Biology, Institute for Cellular and Molecular Biology, The University of Texas at Austin, 1 University Station, A4800, 78712, Austin, TX, USA
| | - Christian Schmidt
- Department of Surgical Oncology and Molecular Oncology, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA
| | - Guido M Sclabas
- Department of Surgical Oncology and Molecular Oncology, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA
- Department of Visceral and Transplantation Surgery, The University of Bern, Inselspital, Bern, 3010, Switzerland
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35
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Mori N, Morishita M, Tsukazaki T, Yamamoto N. Repression of Smad-dependent transforming growth factor-beta signaling by Epstein-Barr virus latent membrane protein 1 through nuclear factor-kappaB. Int J Cancer 2003; 105:661-8. [PMID: 12740915 DOI: 10.1002/ijc.11146] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
EBV-encoded LMP-1 is absolutely required for EBV transformation of cells. Previous studies showed that LMP-1 is responsible for mediating resistance to the anti-proliferative effects of TGF-beta that characterizes EBV-transformed cells. To clarify the mechanisms of resistance to TGF-beta by LMP-1, we examined the effect of expression of LMP-1 on the activity of TGF-beta-responsive promoters. Interestingly, LMP-1 inhibited TGF-beta-responsive promoters activity despite lack of direct interaction of LMP-1 and Smad proteins, intracellular signaling molecules in the TGF-beta signal transduction pathway. Although TGF-beta treatment increased the expression of p15, TGF-beta-induced gene, this effect was counteracted by expression of LMP-1. The repressive effect was mapped to the NF-kappaB activation domains in the cytoplasmic carboxyl terminus of LMP-1. Furthermore, LMP-1-mediated inhibition of TGF-beta-responsive promoter was markedly restored after inhibition of NF-kappaB activity. LMP-1 failed to affect receptor-dependent formation of heteromers containing Smad proteins as well as the DNA-binding activity of Smad proteins. Overexpression of the transcriptional coactivator CBP and p300 abrogated the inhibitory effect of LMP-1 on the TGF-beta-responsive promoter. Our results suggest that LMP-1 represses the TGF-beta signaling through the NF-kappaB signaling pathway at transcriptional level by competing for a limited pool of transcriptional coactivators. These results enhance our understanding of the molecular mechanisms of viral pathogenesis in EBV-associated malignancies.
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MESH Headings
- Animals
- Binding, Competitive
- Carcinoma, Hepatocellular/pathology
- Cell Cycle Proteins/biosynthesis
- Cell Line
- Cell Transformation, Viral/physiology
- Cyclin-Dependent Kinase Inhibitor p15
- Cyclin-Dependent Kinase Inhibitor p16/biosynthesis
- DNA-Binding Proteins/physiology
- Gene Expression Regulation, Viral
- Genes, Reporter
- Genes, p16
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/physiology
- Humans
- I-kappa B Proteins/genetics
- I-kappa B Proteins/physiology
- Liver Neoplasms/pathology
- Lung
- Mink
- Models, Genetic
- NF-KappaB Inhibitor alpha
- NF-kappa B/metabolism
- Nuclear Proteins/biosynthesis
- Nuclear Proteins/genetics
- Nuclear Proteins/physiology
- Promoter Regions, Genetic
- Protein Serine-Threonine Kinases
- Receptor, Transforming Growth Factor-beta Type II
- Receptors, Transforming Growth Factor beta/physiology
- Recombinant Fusion Proteins/physiology
- Signal Transduction
- Smad2 Protein
- Smad3 Protein
- Smad4 Protein
- Trans-Activators/biosynthesis
- Trans-Activators/genetics
- Trans-Activators/physiology
- Transcription, Genetic
- Transfection
- Transforming Growth Factor beta/antagonists & inhibitors
- Tumor Suppressor Proteins
- Viral Matrix Proteins/physiology
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Affiliation(s)
- Naoki Mori
- Department of Virology, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan.
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36
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Abstract
TGF-beta insensitivity has been reported in some malignant lymphomas showing loss of TGF-beta receptor expression. This loss of TGF-beta sensitivity is thought to have removed the immunosuppressive properties of TGF-beta, thus enhancing cell proliferation and resulting in the development of malignant lymphoma. In this study, we performed immunohistochemical stains for TGF-beta1, TGF-beta RI and TGF-beta RII in primary gastric B-cell lymphomas in order to ascertain their possible roles in lymphomagenesis. A total of twenty cases of gastric lymphoma were included. All cases of low- and high-grade lymphomas were negative or weakly positive for TGF-beta1. Reactive lymphoid cells, including the germinal center, were also negative for TGF-beta1. In contrast, reactive germinal centers showed moderate to strong cytoplasmic or membranous staining for TGF-beta RI and TGF-beta RII. In malignant lymphomas, TGF-beta RI expression was maintained in all cases of low- and high-grade lymphomas. In contrast, TGF-beta RII expression was decreased in all low- and high-grade lymphoma cells. These findings suggest that the loss of TGF-beta RII expression may be involved in the lymphomagenesis of the stomach.
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Affiliation(s)
- Jai Hyang Go
- Department of Pathology, Dankook University College of Medicine, Chungnam, Korea.
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37
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Horndasch M, Raschke EE, Bommer G, Schuhmacher M, Dumont E, Kuklik-Roos C, Eick D, Kempkes B. Epstein-Barr virus antagonizes the antiproliferative activity of transforming growth factor-beta but does not abolish its signaling. Int J Cancer 2002; 101:442-7. [PMID: 12216072 DOI: 10.1002/ijc.10626] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
TGF-beta induces apoptosis and inhibits the proliferation of EBV-negative B-lymphoma cell lines. In contrast, EBV-immortalized B cells are resistant to both the proapoptotic and the antiproliferative activities of TGF-beta. We have generated a lymphoblastoid cell line, in which we can switch on and off the EBV-specific transcriptional program driven by EBNA2. When these cells express the EBNA2-driven phenotype, they are resistant to TGF-beta-mediated growth arrest. We used this cell line to readdress the question of how EBV can overcome the antiproliferative TGF-beta activity. We show here that EBV-driven cells remain TGF-beta-responsive since TGF-beta target genes are readily induced. Thus, EBV can overcome TGF-beta-mediated growth arrest without interfering with the core machinery of the TGF-beta signaling pathway, which links ligand binding to the induction of TGF-beta target genes.
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Affiliation(s)
- Manuela Horndasch
- Institute of Clinical Molecular Biology and Tumor Genetics, GSF-Research Center for Environment and Health, Munich, Germany
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38
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Prokova V, Mosialos G, Kardassis D. Inhibition of transforming growth factor beta signaling and Smad-dependent activation of transcription by the Latent Membrane Protein 1 of Epstein-Barr virus. J Biol Chem 2002; 277:9342-50. [PMID: 11781310 DOI: 10.1074/jbc.m109099200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inhibition of transforming growth factor beta (TGFbeta) signaling by the Epstein-Barr virus Latent Membrane Protein 1 (LMP1) may account, at least in part, for the oncogenic activity of LMP1. We found that LMP1 is a potent inhibitor of TGFbeta signaling and Smad-dependent activation of transcription in 293 epithelial cells and COS-7 fibroblasts. LMP1 strongly inhibited the uninduced and the Smad-inducible activity of the promoters of the human p21/WAF1/Cip1 gene and the mouse Smad7 gene. Inhibition of TGFbeta signaling and Smad-dependent activation of transcription by LMP1 was greatly reduced by deletion of both C-terminal activating regions 1 and 2 of LMP1 as well as by overexpression of a non-degradable form of IkappaB. In contrast, specific inhibitors of p38 kinase or MEK kinase did not reverse the inhibitory activity of LMP1. TGFbeta signaling was enhanced by overexpression of dominant negative forms of the LMP1 effectors TRAF2, NIK, and IKKbeta and was abolished by overexpression of p65/RelA or a p50/p65 fusion protein. Deletion of the transactivation domain of p65 abolished its inhibitory activity. Immunoblotting and immunofluorescence microscopy indicated that suppression of TGFbeta signaling and Smad transcriptional activity by LMP1 was not due to Smad degradation or cytoplasmic retention suggesting that LMP1 affects the nuclear function of Smad proteins. Our data are consistent with an essential role of NF-kappaB activation by LMP1 in the inhibition of TGFbeta signaling and Smad-mediated transcriptional responses.
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Affiliation(s)
- Vassiliki Prokova
- Department of Basic Sciences, University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Heraklion GR-71110, Greece
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Bacon AL, Farrington SM, Dunlop MG. Mutation frequency in coding and non-coding repeat sequences in mismatch repair deficient cells derived from normal human tissue. Oncogene 2001; 20:7464-71. [PMID: 11709717 DOI: 10.1038/sj.onc.1204973] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2001] [Revised: 09/05/2001] [Accepted: 09/13/2001] [Indexed: 01/02/2023]
Abstract
Repetitive tracts within the coding regions of TGFBR2 and BAX are frequently mutated in mismatch repair deficient tumours and are implicated in tumour progression. However, there has been little study of the balance between selection pressure and inherent instability at sequences within these genes. To determine whether TGFBR2 and BAX are inherently prone to mutations in the presence of MMR defects, we studied MMR deficient cells derived from B-lymphocytes. By analysing cells derived from normal tissue we aimed to minimize the effects of selection pressures that bias the apparent frequency of mutation. We definitively show that certain sequences, usually repaired by MMR, are inherently unstable. Using a small pool PCR technique we confirmed these cells exhibit microsatellite instability. Additionally, we demonstrate that MMR deficiency results in an excess of mutations, specifically at the poly(A)(10) tract compared to other regions of the TGFBR2 gene (P<0.001). Conversely, an excess of mutations does not appear to arise at the poly(G)(8) tract of the BAX gene. These studies provide insight into the mechanism by which TGFBR2 and BAX genes become mutated during tumorigenesis. These findings invoke the notion of "unmasking" specific hypermutable sequences in particular genes adding further complexity to the concept of the mutator phenotype.
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Affiliation(s)
- A L Bacon
- Department of Oncology and MRC Human Genetics Unit, Western General Hospital, University of Edinburgh, Crewe Road, Edinburgh, EH4 2XU, UK
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Abstract
Epstein-Barr virus (EBV) latent infection is tightly associated with the development of lymphoid and epithelial human malignancies. The disruption of cell-growth checkpoints is mediated by a limited number of viral proteins that interfere with signal transduction mechanisms and transcription control in the infected cell. Genetic and biochemical evidence supports the notion that EBV-mediated transformation relies extensively on interference with cytokine signaling networks. This is achieved through direct modulation of cytokine receptor signaling mechanisms as well as alterations in the expression levels of various cytokines. The principal effector of these interventions is the EBV latent membrane protein 1 (LMP1) which plays a central role in the transformation process. This viral protein mimics activated receptors of the tumor necrosis factor receptor superfamily to promote cell growth and antiapoptotic mechanisms. LMP1 and other EBV latent proteins upregulate cytokines and growth factors which participate in autocrine and paracrine loops that are likely to promote cell transformation and modulate immune responses. This report will review the molecular mechanisms that underlie the disruption of cytokine signaling mechanisms in EBV-mediated transformation with a particular emphasis on the LMP1 mechanism of function.
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Affiliation(s)
- G Mosialos
- Institute of Immunology, Biomedical Sciences Research Center Al. Fleming, 14-16 Al. Fleming Str., Vari 16672, Greece.
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Abstract
Transforming growth factor beta (TGF-beta) is an effective and ubiquitous mediator of cell growth. The significance of this cytokine in cancer susceptibility, cancer development and progression has become apparent over the past few years. TGF-beta plays various roles in the process of malignant progression. It is a potent inhibitor of normal stromal, hematopoietic, and epithelial cell growth. However, at some point during cancer development the majority of transformed cells become either partly or completely resistant to TGF-beta growth inhibition. There is growing evidence that in the later stages of cancer development TGF-beta is actively secreted by tumor cells and not merely acts as a bystander but rather contributes to cell growth, invasion, and metastasis and decreases host-tumor immune responses. Subtle alteration of TGF-beta signaling may also contribute to the development of cancer. These various effects are tissue and tumor dependent. Identifying and understanding TGF-beta signaling pathway abnormalities in various malignancies is a promising avenue of study that may yield new modalities to both prevent and treat cancer. The nature, prevalence, and significance of TGF-beta signaling pathway alterations in various forms of human cancer as well as potential preventive and therapeutic interventions are discussed in this review.
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Affiliation(s)
- B Pasche
- Division of Hematology/Oncology, Department of Medicine, Northwestern University Medical School, 710 North Fairbanks, Room 8410, Chicago, IL 60611, USA.
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Inman GJ, Binné UK, Parker GA, Farrell PJ, Allday MJ. Activators of the Epstein-Barr virus lytic program concomitantly induce apoptosis, but lytic gene expression protects from cell death. J Virol 2001; 75:2400-10. [PMID: 11160743 PMCID: PMC114823 DOI: 10.1128/jvi.75.5.2400-2410.2001] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Expression of the lytic cycle genes of Epstain-Barr virus (EBV) is induced in type I Burkitt's lymphoma-derived cells by treatment with phorbol esters (e.g., phorbol myristate acetate [PMA]), anti-immunoglobulin, or the cytokine transforming growth factor beta (TGF-beta). Concomitantly, all these agents induce apoptosis as judged by a sub-G1 fluorescence-activated cell sorter (FACS) profile, proteolytic cleavage of poly(ADP-ribose) polymerase (PARP) and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. However, caspase activation is not required for induction of the lytic cycle since the latter is not blocked by the caspase inhibitor ZVAD. Furthermore, not all agents that induce apoptosis in these cultures (for example, cisplatin and ceramide) induce the EBV lytic programme. Although it is closely associated with the lytic cycle, apoptosis is neither necessary nor sufficient for its activation. Multiparameter FACS analysis of cultures treated with PMA, anti-Ig, or TGF-beta revealed BZLF1-expressing cells distributed in different phases of the cell cycle according to which inducer was used. However, BZLF1-positive cells did not appear to undergo apoptosis and accumulate with a sub-G1 DNA content, irrespective of the inducer used. This result, which suggests that lytic gene expression is protective, was confirmed and extended by immunofluorescence staining doubled with TUNEL analysis. BZLF1- and also gp350-expressing cells were almost always shown to be negative for TUNEL staining. Similar experiments using EBV-positive and -negative subclones of Akata BL cells carrying an episomal BZLF1 reporter plasmid confirmed that protection from apoptosis was associated with the presence of the EBV genome. Finally, treatment with phosphonoacetic acid or acyclovir prior to induction with PMA, anti-Ig, or TGF-beta blocked the protective effect in Mutu-I cells. These data suggest that a late gene product(s) may be particularly important for protection against caspase activity and cell death.
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Affiliation(s)
- G J Inman
- Section of Virology and Cell Biology and Ludwig Institute for Cancer Research, Imperial College of Science Technology and Medicine, London W2 1PG, United Kingdom
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43
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Abstract
Transforming growth factor beta (TGF-beta) is an effective and ubiquitous mediator of cell growth. The significance of this cytokine in cancer susceptibility, cancer development and progression has become apparent over the past few years. TGF-beta plays various roles in the process of malignant progression. It is a potent inhibitor of normal stromal, hematopoietic, and epithelial cell growth. However, at some point during cancer development the majority of transformed cells become either partly or completely resistant to TGF-beta growth inhibition. There is growing evidence that in the later stages of cancer development TGF-beta is actively secreted by tumor cells and not merely acts as a bystander but rather contributes to cell growth, invasion, and metastasis and decreases host-tumor immune responses. Subtle alteration of TGF-beta signaling may also contribute to the development of cancer. These various effects are tissue and tumor dependent. Identifying and understanding TGF-beta signaling pathway abnormalities in various malignancies is a promising avenue of study that may yield new modalities to both prevent and treat cancer. The nature, prevalence, and significance of TGF-beta signaling pathway alterations in various forms of human cancer as well as potential preventive and therapeutic interventions are discussed in this review.
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Affiliation(s)
- B Pasche
- Division of Hematology/Oncology, Department of Medicine, Northwestern University Medical School, 710 North Fairbanks, Room 8410, Chicago, IL 60611, USA.
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44
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Inman GJ, Allday MJ. Apoptosis induced by TGF-beta 1 in Burkitt's lymphoma cells is caspase 8 dependent but is death receptor independent. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:2500-10. [PMID: 10946276 DOI: 10.4049/jimmunol.165.5.2500] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
TGF-beta is a potent inducer of apoptosis in many Burkitt's lymphoma (BL) cell lines. In this study, we characterize this apoptotic process in the EBV-negative BL41 cell line. Induction of apoptosis was detected as early as 8 h after TGF-beta treatment, as assayed by TUNEL and poly(ADP-ribose) polymerase cleavage. FACS analysis demonstrates that this proceeds predominately from the G1, but also from the G2/M phases of the cell cycle. We observed no early detectable changes in the steady-state levels of Bcl-2 and several of its family members after TGF-beta treatment. We detected cleavage of caspases 2, 3, 7, 8, and 9 into their active subunits. Consistent with the involvement of these enzymes in TGF-beta-mediated apoptosis, the broad spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(Ome)-flouromethylketone (ZVAD-fmk) blocked TGF-beta-induced apoptosis and revealed a G1 arrest in treated cells. Use of specific caspase inhibitors revealed that the induction of apoptosis is caspase 8 dependent, but caspase 3 independent. Activation of caspase 8 has been shown to be a critical event in death receptor-mediated apoptosis. However, TGF-beta treatment of BL41 cells was found not to affect the cell surface expression of Fas, TNF-R1, DR3, DR4, or DR5, or the steady-state expression levels of Fas ligand, TNF-R1, DR3, DR4, and DR5. Furthermore, blocking experiments indicated that TGF-beta-mediated apoptosis is not dependent on Fas ligand, TNF-alpha, tumor necrosis-like apoptosis-inducing ligand, or TNF-like weak inducer of apoptosis signaling. Therefore, it appears that TGF-beta induces apoptosis in BL cell lines via caspase 8 in a death receptor-independent fashion.
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Affiliation(s)
- G J Inman
- Section of Virology and Cell Biology and the Ludwig Institute for Cancer Research, Imperial College of Science, Technology and Medicine, St. Mary's Campus, London, United Kingdom
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