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Berežni S, Mimica-Dukić N, Domina G, Raimondo FM, Orčić D. Anthriscus sylvestris-Noxious Weed or Sustainable Source of Bioactive Lignans? PLANTS (BASEL, SWITZERLAND) 2024; 13:1087. [PMID: 38674496 PMCID: PMC11053937 DOI: 10.3390/plants13081087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 04/08/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024]
Abstract
Anthriscus sylvestris (L.) Hoffm. (Apiaceae), commonly known as wild chervil, has gained scientific interest owing to its diverse phytochemical profile and potential therapeutic applications. The plant, despite being categorized as a noxious weed, is traditionally used in treating various conditions like headaches, dressing wounds, and as a tonic, antitussive, antipyretic, analgesic, and diuretic. Its pharmacological importance stems from containing diverse bioactive lignans, especially aryltetralins and dibenzylbutyrolactones. One of the main compounds of A. sylvestris, deoxypodophyllotoxin, among its wide-ranging effects, including antitumor, antiproliferative, antiplatelet aggregation, antiviral, anti-inflammatory, and insecticidal properties, serves as a pivotal precursor to epipodophyllotoxin, crucial in the semisynthesis of cytostatic agents like etoposide and teniposide. The main starting compound for these anticancer medicines was podophyllotoxin, intensively isolated from Sinopodophyllum hexandrum, now listed as an endangered species due to overexploitation. Since new species are being investigated as potential sources, A. sylvestris emerges as a highly promising candidate owing to its abundant lignan content. This review summarizes the current knowledge on A. sylvestris, investigating its biological and morphological characteristics, and pharmacological properties. Emphasizing the biological activities and structure-activity relationship, this review underscores its therapeutic potential, thus encouraging further exploration and utilization of this valuable plant resource.
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Affiliation(s)
- Sanja Berežni
- Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 3, 21000 Novi Sad, Serbia; (N.M.-D.); (D.O.)
| | - Neda Mimica-Dukić
- Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 3, 21000 Novi Sad, Serbia; (N.M.-D.); (D.O.)
| | - Gianniantonio Domina
- Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze, bldg. 4, 90128 Palermo, Italy;
| | - Francesco Maria Raimondo
- PLANTA/Center for Research, Documentation and Training, Via Serraglio Vecchio 28, 90123 Palermo, Italy;
| | - Dejan Orčić
- Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 3, 21000 Novi Sad, Serbia; (N.M.-D.); (D.O.)
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Bellon M, Nicot C. HTLV-1 Tax Tug-of-War: Cellular Senescence and Death or Cellular Transformation. Pathogens 2024; 13:87. [PMID: 38276160 PMCID: PMC10820833 DOI: 10.3390/pathogens13010087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/11/2024] [Accepted: 01/15/2024] [Indexed: 01/27/2024] Open
Abstract
Human T cell leukemia virus type 1 (HTLV-1) is a retrovirus associated with a lymphoproliferative disease known as adult T cell leukemia/lymphoma (ATLL). HTLV-1 infection efficiently transforms human T cells in vivo and in vitro. The virus does not transduce a proto-oncogene, nor does it integrate into tumor-promoting genomic sites. Instead, HTLV-1 uses a random mutagenesis model, resulting in cellular transformation. Expression of the viral protein Tax is critical for the immortalization of infected cells by targeting specific cellular signaling pathways. However, Tax is highly immunogenic and represents the main target for the elimination of virally infected cells by host cytotoxic T cells (CTLs). In addition, Tax expression in naïve cells induces pro-apoptotic signals and has been associated with the induction of non-replicative cellular senescence. This review will explore these conundrums and discuss the mechanisms used by the Tax viral oncoprotein to influence life-and-death cellular decisions and affect HTLV-1 pathogenesis.
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Affiliation(s)
| | - Christophe Nicot
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, USA;
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Reichert M. Proteome analysis of sheep B lymphocytes in the course of bovine leukemia virus-induced leukemia. Exp Biol Med (Maywood) 2017; 242:1363-1375. [PMID: 28436273 DOI: 10.1177/1535370217705864] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Presented are the results of a study of the expression pattern of different proteins in the course of bovine leukemia virus-induced leukemia in experimental sheep and I discuss how the obtained data may be useful in gaining a better understanding of the pathogenesis of the disease, diagnosis, and for the selection of possible therapeutic targets. In cattle, the disease is characterized by life-long persistent lymphocytosis leading to leukemia/lymphoma in about 5% of infected animals. In sheep, as opposed to cattle, the course of the disease is always fatal and clinical symptoms usually occur within a three-year period after infection. For this reason, sheep are an excellent experimental model of retrovirus-induced leukemia. This model can be useful for human pathology, as bovine leukemia virus is closely related to human T-lymphotropic virus type 1. The data presented here provide novel insights into the molecular mechanisms of the bovine leukemia virus-induced tumorigenic process and indicate the potential marker proteins both for monitoring progression of the disease and as possible targets of pharmacological intervention. A study of the proteome of B lymphocytes from four leukemic sheep revealed 11 proteins with altered expression. Among them, cytoskeleton and intermediate filament proteins were the most abundant, although proteins belonging to the other functional groups, i.e. enzymes, regulatory proteins, and transcription factors, were also present. It was found that trypsin inhibitor, platelet factor 4, thrombospondin 1, vasodilator-stimulated phosphoprotein, fibrinogen alpha chain, zyxin, filamin-A, and vitamin D-binding protein were downregulated, whereas cleavage and polyadenylation specificity factor subunit 5, non-POU domain-containing octamer-binding protein and small glutamine-rich tetratricopeptide repeat-containing protein alpha were upregulated. Discussed are the possible mechanisms of their altered expression and its significance in the bovine leukemia virus-induced leukemogenic process. Impact statement The submitted manuscript provides new data on the molecular mechanisms of BLV-induced tumorigenic process indicating the potential marker proteins both for monitoring the progression of the disease and as possible targets of pharmacological intervention. This is to my knowledge the first study of the proteome of the transformed lymphocytes in the course of bovine leukemia virus-induced leukemia in susceptible animals. BLV can be considered as useful model for related human pathogen - HTLV-1, another member of the deltaretrovirus genus evolutionary closely related to BLV. Information gathered in this study can be useful to speculate on possible shared mechanisms of deltaretrovirus-induced carcinogenesis.
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Affiliation(s)
- Michal Reichert
- Department of Pathology, National Veterinary Research Institute, Pulawy 24-100, Poland
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Kawamura M, Umehara D, Odahara Y, Miyake A, Ngo MH, Ohsato Y, Hisasue M, Nakaya MA, Watanabe S, Nishigaki K. AKT capture by feline leukemia virus. Arch Virol 2016; 162:1031-1036. [PMID: 28005210 DOI: 10.1007/s00705-016-3192-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 12/01/2016] [Indexed: 10/20/2022]
Abstract
Oncogene-containing retroviruses are generated by recombination events between viral and cellular sequences, a phenomenon called "oncogene capture". The captured cellular genes, referred to as "v-onc" genes, then acquire new oncogenic properties. We report a novel feline leukemia virus (FeLV), designated "FeLV-AKT", that has captured feline c-AKT1 in feline lymphoma. FeLV-AKT contains a gag-AKT fusion gene that encodes the myristoylated Gag matrix protein and the kinase domain of feline c-AKT1, but not its pleckstrin homology domain. Therefore, it differs structurally from the v-Akt gene of murine retrovirus AKT8. AKT may be involved in the mechanisms underlying malignant diseases in cats.
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Affiliation(s)
- Maki Kawamura
- Laboratory of Molecular Immunology and Infectious Disease, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan
| | - Daigo Umehara
- Laboratory of Molecular Immunology and Infectious Disease, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan
| | - Yuka Odahara
- Laboratory of Molecular Immunology and Infectious Disease, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan
| | - Ariko Miyake
- Laboratory of Molecular Immunology and Infectious Disease, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan
| | - Minh Ha Ngo
- Laboratory of Molecular Immunology and Infectious Disease, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan
| | | | - Masaharu Hisasue
- Laboratory of Internal Medicine 2, Veterinary Medicine, Azabu University, 1-17-71, Fuchinobe, Chuou-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - Masa-Aki Nakaya
- Department of Molecular Biology, Yokohama City University School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan
| | - Shinya Watanabe
- Laboratory of Molecular Immunology and Infectious Disease, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan
| | - Kazuo Nishigaki
- Laboratory of Molecular Immunology and Infectious Disease, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan. .,Laboratory of Molecular Immunology and Infectious Disease, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan.
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Oncogenic mutations in the FBXW7 gene of adult T-cell leukemia patients. Proc Natl Acad Sci U S A 2016; 113:6731-6. [PMID: 27247421 DOI: 10.1073/pnas.1601537113] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-I) is associated with adult T-cell leukemia (ATL), an aggressive lymphoproliferative disease with a dismal prognosis. We have previously described the presence of Notch1 activating mutations and constitutive Notch1 signaling in patients with acute ATL. In this study, we report a high frequency of F-box and WD repeat domain containing 7 (FBXW7)/hCDC4 mutations within the WD40 substrate-binding domain in 8 of 32 acute ATL patients (25%). Functionally, ATL FBXW7 mutants lost their ability to interact with intracellular Notch (NICD), resulting in increased protein stability and constitutive Notch1 signaling. Consistent with the loss-of-function found in ATL patients, expression of WT FBXW7 in several patient-derived ATL lines demonstrated strong tumor-suppressor activity characterized by reduced proliferation of ATL cells. Remarkably, two FBXW7 mutants, D510E and D527G, demonstrated oncogenic activity when expressed in the presence of HTLV-I Tax, mutated p53 R276H, or c-Myc F138C found in human cancers. Transforming activity was further demonstrated by the ability of the FBXW7 D510E mutant to provide IL-2-independent growth of Tax-immortalized human T cells and increase the tumor formation in a xenograft mouse model of ATL. This study suggests that FBXW7, normally a tumor suppressor, can act as an oncogene when mutated and may play an important role in the pathogenesis of ATL.
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Molecular Studies of HTLV-1 Replication: An Update. Viruses 2016; 8:v8020031. [PMID: 26828513 PMCID: PMC4776186 DOI: 10.3390/v8020031] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 01/13/2016] [Accepted: 01/18/2016] [Indexed: 02/08/2023] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) was the first human retrovirus discovered. Studies on HTLV-1 have been instrumental for our understanding of the molecular pathology of virus-induced cancers. HTLV-1 is the etiological agent of an adult T-cell leukemia (ATL) and can lead to a variety of neurological pathologies, including HTLV-1-associated-myelopathy/tropical spastic paraparesis (HAM/TSP). The ability to treat the aggressive ATL subtypes remains inadequate. HTLV-1 replicates by (1) an infectious cycle involving virus budding and infection of new permissive target cells and (2) mitotic division of cells harboring an integrated provirus. Virus replication initiates host antiviral immunity and the checkpoint control of cell proliferation, but HTLV-1 has evolved elegant strategies to counteract these host defense mechanisms to allow for virus persistence. The study of the molecular biology of HTLV-1 replication has provided crucial information for understanding HTLV-1 replication as well as aspects of viral replication that are shared between HTLV-1 and human immunodeficiency virus type 1 (HIV-1). Here in this review, we discuss the various stages of the virus replication cycle—both foundational knowledge as well as current updates of ongoing research that is important for understanding HTLV-1 molecular pathogenesis as well as in developing novel therapeutic strategies.
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Bellon M, Nicot C. Multiple Pathways Control the Reactivation of Telomerase in HTLV-I-Associated Leukemia. ACTA ACUST UNITED AC 2015; 2. [PMID: 26430700 DOI: 10.15436/2377-0902.15.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
While telomerase (hTERT) activity is absent from normal somatic cells, reactivation of hTERT expression is a hallmark of cancer cells. Telomerase activity is required for avoiding replicative senescence and supports immortalization of cellular proliferation. Only a minority of cancer cells rely on a telomerase-independent process known as alternative lengthening of telomeres, ALT, to sustain cancer cell proliferation. Multiple genetic, epigenetic, and viral mechanisms have been found to de-regulate telomerase gene expression, thereby increasing the risk of cellular transformation. Here, we review the different strategies used by the Human T-cell leukemia virus type 1, HTLV-I, to activate hTERT expression and stimulate its enzymatic activity in virally infected CD4 T cells. The implications of hTERT reactivation in HTLV-I pathogenesis and disease treatment are discussed.
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Affiliation(s)
- Marcia Bellon
- Department of Pathology and Laboratory Medicine, Center for Viral Oncology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Christophe Nicot
- Department of Pathology and Laboratory Medicine, Center for Viral Oncology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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Ren T, Takahashi Y, Liu X, Loughran TP, Sun SC, Wang HG, Cheng H. HTLV-1 Tax deregulates autophagy by recruiting autophagic molecules into lipid raft microdomains. Oncogene 2015; 34:334-45. [PMID: 24362528 PMCID: PMC4067462 DOI: 10.1038/onc.2013.552] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 10/14/2013] [Accepted: 11/01/2013] [Indexed: 12/13/2022]
Abstract
The retroviral oncoprotein Tax from human T-cell leukemia virus type 1 (HTLV-1), an etiological factor that causes adult T-cell leukemia and lymphoma, has a crucial role in initiating T-lymphocyte transformation by inducing oncogenic signaling activation. We here report that Tax is a determining factor for dysregulation of autophagy in HTLV-1-transformed T cells and Tax-immortalized CD4 memory T cells. Tax facilitated autophagic process by activating inhibitor of κB (IκB) kinase (IKK) complex, which subsequently recruited an autophagy molecular complex containing Beclin1 and Bif-1 to the lipid raft microdomains. Tax engaged a crosstalk between IKK complex and autophagic molecule complex by directly interacting with both complexes, promoting assembly of LC3+ autophagosomes. Moreover, expression of lipid raft-targeted Bif-1 or Beclin1 was sufficient to induce formation of LC3+ autophagosomes, suggesting that Tax recruitment of autophagic molecules to lipid rafts is a dominant strategy to deregulate autophagy in the context of HTLV-1 transformation of T cells. Furthermore, depletion of autophagy molecules such as Beclin1 and PI3 kinase class III resulted in impaired growth of HTLV-1-transformed T cells, indicating a critical role of Tax-deregulated autophagy in promoting survival and transformation of virally infected T cells.
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Affiliation(s)
- Tong Ren
- Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, PA 17033
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA 17033
| | - Yoshinori Takahashi
- Department of Pharmacology, Penn State University College of Medicine, Hershey, PA 17033
| | - Xin Liu
- Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, PA 17033
| | - Thomas P. Loughran
- Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, PA 17033
| | - Shao-Cong Sun
- Department of Immunology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Hong-Gang Wang
- Department of Pharmacology, Penn State University College of Medicine, Hershey, PA 17033
| | - Hua Cheng
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201
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Taniguchi H, Hasegawa H, Sasaki D, Ando K, Sawayama Y, Imanishi D, Taguchi J, Imaizumi Y, Hata T, Tsukasaki K, Uno N, Morinaga Y, Yanagihara K, Miyazaki Y. Heat shock protein 90 inhibitor NVP-AUY922 exerts potent activity against adult T-cell leukemia-lymphoma cells. Cancer Sci 2014; 105:1601-8. [PMID: 25263741 PMCID: PMC4317953 DOI: 10.1111/cas.12540] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 09/16/2014] [Accepted: 09/19/2014] [Indexed: 02/04/2023] Open
Abstract
Adult T-cell leukemia–lymphoma (ATL), an aggressive neoplasm etiologically associated with HTLV-1, is a chemoresistant malignancy. Heat shock protein 90 (HSP90) is involved in folding and functions as a chaperone for multiple client proteins, many of which are important in tumorigenesis. In this study, we examined NVP-AUY922 (AUY922), a second generation isoxazole-based non-geldanamycin HSP90 inhibitor, and confirmed its effects on survival of ATL-related cell lines. Analysis using FACS revealed that AUY922 induced cell-cycle arrest and apoptosis; it also inhibited the growth of primary ATL cells, but not of normal PBMCs. AUY922 caused strong upregulation of HSP70, a surrogate marker of HSP90 inhibition, and a dose-dependent decrease in HSP90 client proteins associated with cell survival, proliferation, and cell cycle in the G1 phase, including phospho-Akt, Akt, IKKα, IKKβ, IKKγ, Cdk4, Cdk6, and survivin. Interestingly, AUY922 induced downregulation of the proviral integration site for Moloney murine leukemia virus (PIM) in ATL cells. The PIM family (PIM-1, -2, -3) is made up of oncogenes that encode a serine/threonine protein kinase family. As PIM kinases have multiple functions involved in cell proliferation, survival, differentiation, apoptosis, and tumorigenesis, their downregulation could play an important role in AUY922-induced death of ATL cells. In fact, SGI-1776, a pan-PIM kinase inhibitor, successfully inhibited the growth of primary ATL cells as well as ATL-related cell lines. Our findings suggest that AUY922 is an effective therapeutic agent for ATL, and PIM kinases may be a novel therapeutic target.
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Affiliation(s)
- Hiroaki Taniguchi
- Department of Hematology, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; Department of Hematology, Sasebo City General Hospital, Sasebo, Japan; Atomic Bomb Disease and Hibakusha Medicine Unit, Department of Hematology, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
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The human adenovirus E4-ORF1 protein subverts discs large 1 to mediate membrane recruitment and dysregulation of phosphatidylinositol 3-kinase. PLoS Pathog 2014; 10:e1004102. [PMID: 24788832 PMCID: PMC4006922 DOI: 10.1371/journal.ppat.1004102] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 03/18/2014] [Indexed: 12/19/2022] Open
Abstract
Adenoviruses infect epithelial cells lining mucous membranes to cause acute diseases in people. They are also utilized as vectors for vaccination and for gene and cancer therapy, as well as tools to discover mechanisms of cancer due to their tumorigenic potential in experimental animals. The adenovirus E4-ORF1 gene encodes an oncoprotein that promotes viral replication, cell survival, and transformation by activating phosphatidylinositol 3-kinase (PI3K). While the mechanism of activation is not understood, this function depends on a complex formed between E4-ORF1 and the membrane-associated cellular PDZ protein Discs Large 1 (Dlg1), a common viral target having both tumor suppressor and oncogenic functions. Here, we report that in human epithelial cells, E4-ORF1 interacts with the regulatory and catalytic subunits of PI3K and elevates their levels. Like PI3K activation, PI3K protein elevation by E4-ORF1 requires Dlg1. We further show that Dlg1, E4-ORF1, and PI3K form a ternary complex at the plasma membrane. At this site, Dlg1 also co-localizes with the activated PI3K effector protein Akt, indicating that the ternary complex mediates PI3K signaling. Signifying the functional importance of the ternary complex, the capacity of E4-ORF1 to induce soft agar growth and focus formation in cells is ablated either by a mutation that prevents E4-ORF1 binding to Dlg1 or by a PI3K inhibitor drug. These results demonstrate that E4-ORF1 interacts with Dlg1 and PI3K to assemble a ternary complex where E4-ORF1 hijacks the Dlg1 oncogenic function to relocate cytoplasmic PI3K to the membrane for constitutive activation. This novel mechanism of Dlg1 subversion by adenovirus to dysregulate PI3K could be used by other pathogenic viruses, such as human papillomavirus, human T-cell leukemia virus type 1, and influenza A virus, which also target Dlg1 and activate PI3K in cells. Adenoviruses cause acute illnesses in people, and are additionally utilized both as vehicles to cure genetic diseases, fight cancer, and deliver vaccines, and as tools to discover how cancers develop due to a capacity to generate tumors in experimental animals. The adenovirus E4-ORF1 protein reprograms cell metabolism to enhance virus production in infected cells and promotes cell survival and tumors by activating the important cellular protein phosphatidylinositol 3-kinase (PI3K). How E4-ORF1 activates PI3K is not known, though this function depends on E4-ORF1 binding to the membrane-associated cellular protein Discs Large 1 (Dlg1), which many different viruses evolved to target. In this study, we identify PI3K as a new direct target of E4-ORF1. Results further show that E4-ORF1 binds to PI3K in the cytoplasm and delivers it to Dlg1 at the membrane where the three proteins form a complex that activates PI3K and induces oncogenic growth in cells. This novel molecular mechanism in which adenovirus subverts Dlg1 to dysregulate PI3K may serve as a paradigm to understand PI3K activation mediated by other important pathogenic viruses, such as human papillomavirus, human T-cell leukemia virus type 1, and influenza A virus, which also target Dlg1 in infected cells.
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Zane L, Yasunaga J, Mitagami Y, Yedavalli V, Tang SW, Chen CY, Ratner L, Lu X, Jeang KT. Wip1 and p53 contribute to HTLV-1 Tax-induced tumorigenesis. Retrovirology 2012; 9:114. [PMID: 23256545 PMCID: PMC3532233 DOI: 10.1186/1742-4690-9-114] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 12/15/2012] [Indexed: 01/07/2023] Open
Abstract
Background Human T-cell Leukemia Virus type 1 (HTLV-1) infects 20 million individuals world-wide and causes Adult T-cell Leukemia/Lymphoma (ATLL), a highly aggressive T-cell cancer. ATLL is refractory to treatment with conventional chemotherapy and fewer than 10% of afflicted individuals survive more than 5 years after diagnosis. HTLV-1 encodes a viral oncoprotein, Tax, that functions in transforming virus-infected T-cells into leukemic cells. All ATLL cases are believed to have reduced p53 activity although only a minority of ATLLs have genetic mutations in their p53 gene. It has been suggested that p53 function is inactivated by the Tax protein. Results Using genetically altered mice, we report here that Tax expression does not achieve a functional equivalence of p53 inactivation as that seen with genetic mutation of p53 (i.e. a p53−/− genotype). Thus, we find statistically significant differences in tumorigenesis between Tax+p53+/+versus Tax+p53−/− mice. We also find a role contributed by the cellular Wip1 phosphatase protein in tumor formation in Tax transgenic mice. Notably, Tax+Wip1−/− mice show statistically significant reduced prevalence of tumorigenesis compared to Tax+Wip1+/+ counterparts. Conclusions Our findings provide new insights into contributions by p53 and Wip1 in the in vivo oncogenesis of Tax-induced tumors in mice.
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Affiliation(s)
- Linda Zane
- Molecular Virology Section, Laboratory of Molecular Microbiology, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0460, USA
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Varicella-zoster virus ORF12 protein activates the phosphatidylinositol 3-kinase/Akt pathway to regulate cell cycle progression. J Virol 2012. [PMID: 23192871 DOI: 10.1128/jvi.02395-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Varicella-zoster virus (VZV) activates the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and alters cell cycle progression, but the viral protein(s) responsible for these activities is unknown. We previously reported that the VZV open reading frame 12 (ORF12) protein triggers phosphorylation of ERK. Here, we demonstrate that the VZV ORF12 protein also activates the PI3K/Akt pathway to regulate cell cycle progression. Transfection of cells with a plasmid expressing the ORF12 protein induced phosphorylation of Akt, which was dependent on PI3K. Infection of cells with wild-type VZV triggered phosphorylation of Akt, while infection with an ORF12 deletion mutant induced less phosphorylated Akt. The activation of Akt by ORF12 protein was associated with its binding to the p85 subunit of PI3K. Infection of cells with wild-type VZV resulted in increased levels of cyclin B1, cyclin D3, and phosphorylated glycogen synthase kinase 3β (GSK-3β), while infection with the ORF12 deletion mutant induced lower levels of these proteins. Wild-type VZV infection reduced the G(1) phase cell population and increased the M phase cell population, while infection with the ORF12 deletion mutant had a reduced effect on the G(1) and M phase populations. Inhibition of Akt activity with LY294002 reduced the G(1) and M phase differences observed in cells infected with wild-type and ORF12 mutant viruses. In conclusion, we have found that the VZV ORF12 protein activates the PI3K/Akt pathway to regulate cell cycle progression. Since VZV replicates in both dividing (e.g., keratinocytes) and nondividing (neurons) cells, the ability of the VZV ORF12 protein to regulate the cell cycle is likely important for VZV replication in various cell types in the body.
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Joh EH, Hollenbaugh JA, Kim B, Kim DH. Pleckstrin homology domain of Akt kinase: a proof of principle for highly specific and effective non-enzymatic anti-cancer target. PLoS One 2012. [PMID: 23189201 PMCID: PMC3506615 DOI: 10.1371/journal.pone.0050424] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
While pharmacological inhibition of Akt kinase has been regarded as a promising anti-cancer strategy, most of the Akt inhibitors that have been developed are enzymatic inhibitors that target the kinase active site of Akt. Another key cellular regulatory event for Akt activation is the translocation of Akt kinase to the cell membrane from the cytoplasm, which is accomplished through the pleckstrin homology (PH) domain of Akt. However, compounds specifically interacting with the PH domain of Akt to inhibit Akt activation are currently limited. Here we identified a compound, lancemaside A (LAN-A), which specifically binds to the PH domain of Akt kinase. First, our mass spectra analysis of cellular Akt kinase isolated from cells treated with LAN-A revealed that LAN-A specifically binds to the PH domain of cellular Akt kinase. Second, we observed that LAN-A inhibits the translocation of Akt kinase to the membrane and thus Akt activation, as examined by the phosphorylation of various downstream targets of Akt such as GSK3β, mTOR and BAD. Third, in a co-cultured cell model containing human lung epithelial cancer cells (A549) and normal human primary lung fibroblasts, LAN-A specifically restricts the growth of the A549 cells. LAN-A also displayed anti-proliferative effects on various human cancer cell lines. Finally, in the A549-luciferase mouse transplant model, LAN-A effectively inhibited A549 cell growth with little evident cytotoxicity. Indeed, the therapeutic index of LAN-A in this mouse model was >250, supporting that LAN-A is a potential lead compound for PH domain targeting as a safe anti-cancer Akt inhibitor.
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Affiliation(s)
- Eun-Ha Joh
- Department of Pharmacy, Kyung-Hee University, Seoul, South Korea
| | - Joseph A. Hollenbaugh
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Baek Kim
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
- * E-mail: (DHK); (BK)
| | - Dong-Hyun Kim
- Department of Pharmacy, Kyung-Hee University, Seoul, South Korea
- * E-mail: (DHK); (BK)
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Yamagishi M, Watanabe T. Molecular hallmarks of adult T cell leukemia. Front Microbiol 2012; 3:334. [PMID: 23060864 PMCID: PMC3444139 DOI: 10.3389/fmicb.2012.00334] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 08/29/2012] [Indexed: 12/20/2022] Open
Abstract
The molecular hallmarks of adult T cell leukemia (ATL) comprise outstanding deregulations of signaling pathways that control the cell cycle, resistance to apoptosis, and proliferation of leukemic cells, all of which have been identified by early excellent studies. Nevertheless, we are now confronted the therapeutic difficulties of ATL that is a most aggressive T cell leukemia/lymphoma. Using next-generation strategies, emerging molecular characteristics such as specific surface markers and an additional catalog of signals affecting the fate of leukemic cells have been added to the molecular hallmarks that constitute an organizing principle for rationalizing the complexities of ATL. Although human T cell leukemia virus type 1 is undoubtedly involved in ATL leukemogenesis, most leukemic cells do not express the viral protein Tax. Instead, cellular gene expression changes dominate homeostasis disorders of infected cells and characteristics of ATL. In this review, we summarize the state of the art of ATL molecular pathology, which supports the biological properties of leukemic cells. In addition, we discuss the recent discovery of two molecular hallmarks of potential generality; an abnormal microRNA pattern and epigenetic reprogramming, which strongly involve the imbalance of the molecular network of lymphocytes. Global analyses of ATL have revealed the functional impact of crosstalk between multifunctional pathways. Clinical and biological studies on signaling inhibitory agents have also revealed novel oncogenic drivers that can be targeted in future. ATL cells, by deregulation of such pathways and their interconnections, may become masters of their own destinies. Recognizing and understanding of the widespread molecular applicability of these concepts will increasingly affect the development of novel strategies for treating ATL.
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Affiliation(s)
- Makoto Yamagishi
- Laboratory of Tumor Cell Biology, Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo Minato-ku, Tokyo, Japan
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15
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Hasui K, Wang J, Tanaka Y, Izumo S, Eizuru Y, Matsuyama T. Development of ultra-super sensitive immunohistochemistry and its application to the etiological study of adult T-cell leukemia/lymphoma. Acta Histochem Cytochem 2012; 45:83-106. [PMID: 22685351 PMCID: PMC3365307 DOI: 10.1267/ahc.11034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 02/14/2012] [Indexed: 01/20/2023] Open
Abstract
Antigen retrieval (AR) and ultra-super sensitive immunohistochemistry (ultra-IHC) have been established for application to archival human pathology specimens. The original ultra-IHC was the ImmunoMax method or the catalyzed signal amplification system (ImmunoMax/CSA method), comprising the streptavidin-biotin complex (sABC) method and catalyzed reporter deposition (CARD) reaction with visualization of its deposition. By introducing procedures to diminish non-specific staining in the original ultra-IHC method, we developed the modified ImmunoMax/CSA method with AR heating sections in an AR solution (heating-AR). The heating-AR and modified ImmunoMax/CSA method visualized expression of the predominantly simple present form of HTLV-1 proviral DNA pX region p40Tax protein (Tax) in adult T-cell leukemia/lymphoma (ATLL) cells in archival pathology specimens in approximately 75% of cases. The simple present form of Tax detected exhibited a close relation with ATLL cell proliferation. We also established a new simplified CSA (nsCSA) system by replacing the sABC method with the secondary antibody- and horse radish peroxidase-labeled polymer reagent method, introducing the pretreatments blocking non-specific binding of secondary antibody reagent, and diminishing the diffusion of deposition in the CARD reaction. Combined with AR treating sections with proteinase K solution (enzymatic-AR), the nsCSA system visualized granular immunostaining of the complex present form of Tax in a small number of ATLL cells in most cases, presenting the possibility of etiological pathological diagnosis of ATLL and suggesting that the complex present form of Tax-positive ATLL cells were young cells derived from ATLL stem cells. The heating-AR and ultra-IHC detected physiological expression of the p53 protein and its probable phosphorylation by Tax in peripheral blood mononuclear cells of peripheral blood tissue specimens from HTLV-1 carriers, as well as physiological and pathological expression of the molecules involved with G1 phase progression and G1–S phase transition (E2F-1, E2F-4, DP-1, and cyclin E) in ATLL and peripheral T-cell lymphoma cells. The ultra-IHC with AR is useful for etiological pathological diagnosis of ATLL since HTLV-1 pathogenicity depends on that of Tax, and can be a useful tool for studies translating advanced molecular biology and pathology to human pathology.
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Affiliation(s)
- Kazuhisa Hasui
- Division of Immunology, Department of Infection and Immunity, Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
- Division of Immunology, Department of Infection and Immunity, Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
| | - Jia Wang
- Division of Immunology, Department of Infection and Immunity, Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
- INAMORI Frontier Research Center, Kyushu University
- Division of Immunology, Department of Infection and Immunity, Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
- INAMORI Frontier Research Center, Kyushu University
| | - Yuetsu Tanaka
- Department of Immunology, Graduate School of Medicine, University of the Ryukyus
- Department of Immunology, Graduate School of Medicine, University of the Ryukyus
| | - Shuji Izumo
- Chronic Viral Diseases Div. of Molecular Pathology, Center for Chronic Viral Diseases (Infection and Immunity), Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
- Chronic Viral Diseases Div. of Molecular Pathology, Center for Chronic Viral Diseases (Infection and Immunity), Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
| | - Yoshito Eizuru
- Chronic Viral Diseases Div. of Persistent & Oncogenic Viruses, Center for Chronic Viral Diseases (Infection and Immunity), Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
- Chronic Viral Diseases Div. of Persistent & Oncogenic Viruses, Center for Chronic Viral Diseases (Infection and Immunity), Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
| | - Takami Matsuyama
- Division of Immunology, Department of Infection and Immunity, Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
- Division of Immunology, Department of Infection and Immunity, Institute Research Center (Health Research Course), Kagoshima University Graduate School of Medical and Dental Sciences
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Saponaro C, Cianciulli A, Calvello R, Dragone T, Iacobazzi F, Panaro MA. The PI3K/Akt pathway is required for LPS activation of microglial cells. Immunopharmacol Immunotoxicol 2012; 34:858-65. [DOI: 10.3109/08923973.2012.665461] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Novel PI3K/Akt inhibitors screened by the cytoprotective function of human immunodeficiency virus type 1 Tat. PLoS One 2011; 6:e21781. [PMID: 21765914 PMCID: PMC3134463 DOI: 10.1371/journal.pone.0021781] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 06/08/2011] [Indexed: 02/07/2023] Open
Abstract
The PI3K/Akt pathway regulates various stress-related cellular responses such as cell survival, cell proliferation, metabolism and protein synthesis. Many cancer cell types display the activation of this pathway, and compounds inhibiting this cell survival pathway have been extensively evaluated as anti-cancer agents. In addition to cancers, several human viruses, such as HTLV, HPV, HCV and HIV-1, also modulate this pathway, presumably in order to extend the life span of the infected target cells for productive viral replication. The expression of HIV-1 Tat protein exhibited the cytoprotective effect in macrophages and a human microglial cell line by inhibiting the negative regulator of this pathway, PTEN. This cytoprotective effect of HIV-1 appears to contribute to the long-term survival and persistent HIV-1 production in human macrophage reservoirs. In this study we exploited the PI3K/Akt dependent cytoprotective effect of Tat-expressing CHME5 cells. We screened a collection of compounds known to modulate inflammation, and identified three novel compounds: Lancemaside A, Compound K and Arctigenin that abolished the cytoprotective phenotype of Tat-expressing CHME5 cells. All three compounds antagonized the kinase activity of Akt. Further detailed signaling studies revealed that each of these three compounds targeted different steps of the PI3K/Akt pathway. Arctigenin regulates the upstream PI3K enzyme from converting PIP2 to PIP3. Lancemaside A1 inhibited the movement of Akt to the plasma membrane, a critical step for Akt activation. Compound K inhibited Akt phosphorylation. This study supports that Tat-expressing CHME5 cells are an effective model system for screening novel PI3K/Akt inhibitors.
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Saggioro D. Anti-apoptotic effect of Tax: an NF-κB path or a CREB way? Viruses 2011; 3:1001-14. [PMID: 21994767 PMCID: PMC3185786 DOI: 10.3390/v3071001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 06/09/2011] [Accepted: 06/11/2011] [Indexed: 12/19/2022] Open
Abstract
The NF-κB pathway is intimately linked to the survival of mammalian cells, and its activation by Tax has consequently been considered important for human T-cell leukemia/lymphoma virus type 1 (HTLV-1)-infected cell resistance to death. Very little emphasis has been given to other mechanisms, although Tax regulates the expression and activity of several cellular genes. The finding that CREB protein is activated in HTLV-1 infected cells underlines the possibility that other mechanisms of survival may be implicated in HTLV-1 infection. Indeed, CREB activation or overexpression plays a role in normal hematopoiesis, as well as in leukemia development, and CREB is considered as a survival factor in various cell systems. A better understanding of the different molecular mechanisms used by Tax to counteract cell death will also help in the development of new therapeutic strategies for HTLV-1 associated diseases.
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Affiliation(s)
- Daniela Saggioro
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, via Gattamelata 64, 35128 Padova, Italy.
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19
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Nakamura Y. Retraction: Anti-adult T-cell leukemia effects of a novel synthetic retinoid, Am80 (Tamibarotene). Cancer Sci 2011; 102:499. [PMID: 21265954 DOI: 10.1111/j.1349-7006.2010.01831.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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NK314 potentiates antitumor activity with adult T-cell leukemia-lymphoma cells by inhibition of dual targets on topoisomerase II{alpha} and DNA-dependent protein kinase. Blood 2011; 117:3575-84. [PMID: 21245486 DOI: 10.1182/blood-2010-02-270439] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Adult T-cell leukemia-lymphoma (ATL) is an aggressive disease, incurable by standard chemotherapy. NK314, a new anticancer agent possessing inhibitory activity specific for topoisomerase IIα (Top2α), inhibited the growth of various ATL cell lines (50% inhibitory concentration: 23-70nM) with more potent activity than that of etoposide. In addition to the induction of DNA double-strand breaks by inhibition of Top2α, NK314 induced degradation of the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), resulting in impaired DNA double-strand break repair. The contribution of DNA-PK to inhibition of cell growth was affirmed by the following results: NK314 inhibited cell growth of M059J (a DNA-PKcs-deficient cell line) and M059K (a cell line with DNA-PKcs present) with the same potency, whereas etoposide exhibited weak inhibition of cell growth with M059K cells. A DNA-PK specific inhibitor, NU7026, enhanced inhibitory activity of etoposide on M059K as well as on ATL cells. These results suggest that NK314 is a dual inhibitor of Top2α and DNA-PK. Because ATL cells express a high amount of DNA-PKcs, NK314 as a dual molecular targeting anticancer agent is a potential therapeutic tool for treatment of ATL.
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Abstract
NF-κB is a pivotal transcription factor that controls cell survival and proliferation in diverse physiological processes. The activity of NF-κB is tightly controlled through its cytoplasmic sequestration by specific inhibitors, IκBs. Various cellular stimuli induce the activation of an IκB kinase, which phosphorylates IκBs and triggers their proteasomal degradation, causing nuclear translocation of activated NF-κB. Under normal conditions, the activation of NF-κB occurs transiently, thus ensuring rapid but temporary induction of target genes. Deregulated NF-κB activation contributes to the development of various diseases, including cancers and immunological disorders. Accumulated studies demonstrate that the NF-κB signaling pathway is a target of several human oncogenic viruses, including the human T cell leukemia virus type 1, the Kaposi sarcoma-associated herpesvirus, and the Epstein-Bar virus. These viruses encode specific oncoproteins that target different signaling components of the NF-κB pathway, leading to persistent activation of NF-κB. This chapter will discuss the molecular mechanisms by which NF-κB is activated by the viral oncoproteins.
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Affiliation(s)
- Shao-Cong Sun
- Department of Immunology, The University of Texas MD Anderson Cancer Center and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030
| | - Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, 1300 York Ave, New York, NY 10065
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22
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Nakamura Y. Retraction: Curcumin targets Akt cell survival signaling pathway in HTLV-I-infected T-cell lines. Cancer Sci 2010; 102:498. [PMID: 21265953 DOI: 10.1111/j.1349-7006.2010.01830.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Jeang KT. HTLV-1 and adult T-cell leukemia: insights into viral transformation of cells 30 years after virus discovery. J Formos Med Assoc 2010; 109:688-93. [PMID: 20970064 DOI: 10.1016/s0929-6646(10)60112-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Revised: 08/02/2010] [Accepted: 08/02/2010] [Indexed: 12/22/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1), the etiological agent of adult T-cell leukemia, was the first human retrovirus to be isolated. It is now the 30(th) anniversary of the initial discovery of HTLV-1. This review discusses recent insights into the role of the HTLV-1 Tax oncoprotein in cellular proliferation and the abrogation of cellular checkpoints that lead to disease progression.
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Affiliation(s)
- Kuan-Teh Jeang
- National Institutes of Health, Bethesda, Maryland 20892, USA.
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24
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Zane L, Sibon D, Legras C, Lachuer J, Wierinckx A, Mehlen P, Delfau-Larue MH, Gessain A, Gout O, Pinatel C, Lançon A, Mortreux F, Wattel E. Clonal expansion of HTLV-1 positive CD8+ cells relies on cIAP-2 but not on c-FLIP expression. Virology 2010; 407:341-51. [DOI: 10.1016/j.virol.2010.07.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 05/11/2010] [Accepted: 07/16/2010] [Indexed: 10/19/2022]
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Watters KM, Dean J, Hasegawa H, Sawa H, Hall W, Sheehy N. Cytokine and growth factor expression by HTLV-1 Lck-tax transgenic cells in SCID mice. AIDS Res Hum Retroviruses 2010; 26:593-603. [PMID: 20438380 DOI: 10.1089/aid.2009.0212] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Tax protein encoded by HTLV-1 plays a key role in the development of ATL in infected individuals. Our previous studies showed that tax transgenic mice develop disease that is almost identical to human ATL, with widespread organ invasion by lymphomatous cells and the development of leukemia. The same pathology develops rapidly in SCID mice engrafted with cells from the transgenic animals. In the present study, we used this SCID model to analyze the expression levels of several cytokines, growth factors, and adhesion molecules to determine their possible involvement in the development of disease. We showed that Tax expression was undetectable at the protein level in the tax-transformed cells used to inoculate the SCID mice and that these cells displayed constitutive NF-kappaB and Akt activity. We demonstrated significant differences in the levels of circulating PDGF-BB, TNF-alpha, sICAM-1, and sVCAM-1 in inoculated animals. Cell-surface staining of the tax transgenic cells showed that they do not express receptors for any of the upregulated growth factors. Significant differences were not found in the secreted levels of bFGF, MMP9, VEGF, or E-selectin, whereas IL-2, IL-15, IL-6, IL-1beta, and IFN-gamma expression was undetectable. Even though the number of factors analyzed is limited, our study identified TNF-alpha, PDGF-BB, and the adhesion molecules sICAM-1 and sVCAM-1 as factors that may contribute to the high levels of organ infiltration by leukemic cells in this tax transgenic SCID model.
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Affiliation(s)
- Karen M. Watters
- UCD Centre for Research in Infectious Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Jonathan Dean
- UCD Centre for Research in Infectious Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Hideki Hasegawa
- Department of Pathology, National Institute of Infectious Diseases, Gakuen, Musashimurayama-shi, Tokyo, Japan
| | - Hirofumi Sawa
- Department of Molecular Pathobiology, Research Center for Zoonosis Control, and Global COE Program, Hokkaido University, Sapporo, Japan
| | - William Hall
- UCD Centre for Research in Infectious Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Noreen Sheehy
- UCD Centre for Research in Infectious Diseases, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
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Ito S, Oyake T, Murai K, Ishida Y. Deguelin suppresses cell proliferation via the inhibition of survivin expression and STAT3 phosphorylation in HTLV-1-transformed T cells. Leuk Res 2009; 34:352-7. [PMID: 19781773 DOI: 10.1016/j.leukres.2009.09.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 08/03/2009] [Accepted: 09/04/2009] [Indexed: 11/30/2022]
Abstract
Adult T-cell leukemia (ATL) is an aggressive malignancy of peripheral T cells infected with human T-cell leukemia virus type 1 (HTLV-1). The prognosis of aggressive ATL patients remains poor because of its resistance to conventional chemotherapy. We examined the effect of deguelin, a naturally occurring rotenoid, on HTLV-1-transformed T-cell lines, KUT-1 and MT-2 cells. We found that deguelin suppressed cell proliferation and induced cell death in these cells. Immunoblot analysis showed the inhibition of survivin expression and signal transducers, and activators of transcription (STAT) 3 phosphorylation of both cells. We also observed the cleavage of caspase-3 and poly(ADP-ribose) polymerase (PARP) in deguelin-treated cells, indicating that deguelin induces caspase-dependent apoptosis in these cells. Furthermore, proteasome inhibitor MG132 prevented the down-regulation of survivin expression and STAT3 dephosphorylation by deguelin, suggesting that the action mechanism of deguelin involves the degradation of survivin and phosphorylated STAT3 through the ubiquitin/proteasome pathway. Our data indicate that deguelin presents a potent anti-proliferative effect in part via the down-regulation of survivin expression and STAT3 phosphorylation in HTLV-1-transformed cells. Deguelin merits further investigation as a potential chemotherapeutic agent for ATL.
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Affiliation(s)
- Shigeki Ito
- Hematology & Oncology, Internal Medicine, Iwate Medical University School of Medicine, 19-1 Uchimaru, Morioka, Iwate 020-8505, Japan.
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Taylor JM, Ghorbel S, Nicot C. Genome wide analysis of human genes transcriptionally and post-transcriptionally regulated by the HTLV-I protein p30. BMC Genomics 2009; 10:311. [PMID: 19602286 PMCID: PMC2723137 DOI: 10.1186/1471-2164-10-311] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Accepted: 07/14/2009] [Indexed: 11/16/2022] Open
Abstract
Background Human T-cell leukemia virus type 1 (HTLV-I) is a human retrovirus that is etiologically linked to adult T-cell leukemia (ATL), an aggressive and fatal lymphoproliferative disease. The viral transactivator, Tax, is thought to play an important role during the initial stages of CD4+ T-cell immortalization by HTLV-1. Tax has been shown to activate transcription through CREB/ATF and NF-KB, and to alter numerous signaling pathways. These pleiotropic effects of Tax modify the expression of a wide array of cellular genes. Another viral protein encoded by HTLV-I, p30, has been shown to affect virus replication at the transcriptional and posttranscriptional levels. Little is currently known regarding the effect of p30 on the expression and nuclear export of cellular host mRNA transcripts. Identification of these RNA may reveal new targets and increase our understanding of HTLV-I pathogenesis. In this study, using primary peripheral blood mononuclear cells, we report a genome wide analysis of human genes transcriptionally and post-transcriptionally regulated by the HTLV-I protein p30. Results Using microarray analysis, we analyzed total and cytoplasmic cellular mRNA transcript levels isolated from PBMCs to assess the effect of p30 on cellular RNA transcript expression and their nuclear export. We report p30-dependent transcription resulting in the 2.5 fold up-regulation of 15 genes and the down-regulation of 65 human genes. We further tested nuclear export of cellular mRNA and found that p30 expression also resulted in a 2.5 fold post-transcriptional down-regulation of 90 genes and the up-regulation of 33 genes. Conclusion Overall, our study describes that expression of the HTLV-I protein p30 both positively and negatively alters the expression of cellular transcripts. Our study identifies for the first time the cellular genes for which nuclear export is affected by p30. These results suggest that p30 may possess a more global function with respect to mRNA transcription and the nuclear shuttling of cellular mRNA transcripts. In addition, these alterations in gene expression may play a role in cell transformation and the onset of leukemia.
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Affiliation(s)
- John M Taylor
- Center for Viral Oncology, Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
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Boxus M, Twizere JC, Legros S, Dewulf JF, Kettmann R, Willems L. The HTLV-1 Tax interactome. Retrovirology 2008; 5:76. [PMID: 18702816 PMCID: PMC2533353 DOI: 10.1186/1742-4690-5-76] [Citation(s) in RCA: 195] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Accepted: 08/14/2008] [Indexed: 12/22/2022] Open
Abstract
The Tax1 oncoprotein encoded by Human T-lymphotropic virus type I is a major determinant of viral persistence and pathogenesis. Tax1 affects a wide variety of cellular signalling pathways leading to transcriptional activation, proliferation and ultimately transformation. To carry out these functions, Tax1 interacts with and modulates activity of a number of cellular proteins. In this review, we summarize the present knowledge of the Tax1 interactome and propose a rationale for the broad range of cellular proteins identified so far.
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Affiliation(s)
- Mathieu Boxus
- University Academia Wallonie-Europe, Molecular and Cellular Biology at FUSAGx, Gembloux, Belgium.
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29
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Taylor JM, Nicot C. HTLV-1 and apoptosis: role in cellular transformation and recent advances in therapeutic approaches. Apoptosis 2008; 13:733-47. [PMID: 18421579 DOI: 10.1007/s10495-008-0208-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A universal cellular defense mechanism against viral invasion is the elimination of infected cells through apoptotic cell death. To counteract host defenses many viruses have evolved complex apoptosis evasion strategies. The oncogenic human retrovirus HTLV-1 is the etiological agent of adult-T-cell leukemia/lymphoma (ATLL) and the neurodegenerative disease known as HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The poor prognosis in HTLV-1-induced ATLL is linked to the resistance of neoplastic T cells against conventional therapies and the immuno-compromised state of patients. Nevertheless, several studies have shown that the apoptotic pathway is largely intact and can be reactivated in ATLL tumor cells to induce specific killing. A better understanding of the molecular mechanisms employed by HTLV-1 to counteract cellular death pathways remains an important challenge for future therapies and the treatment of HTLV-1-associated diseases.
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Affiliation(s)
- John M Taylor
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kansas Medical Center, 3025 Wahl Hall West, 3901 Rainbow Blvd., Kansas City, KS 66160, USA
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30
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Human T-cell leukemia virus type 1 infection leads to arrest in the G1 phase of the cell cycle. J Virol 2008; 82:8442-55. [PMID: 18596104 DOI: 10.1128/jvi.00091-08] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Infection by the human T-cell leukemia virus type 1 (HTLV-1) is thought to cause dysregulated T-cell proliferation, which in turn leads to adult T-cell leukemia/lymphoma. Early cellular changes after HTLV-1 infection have been difficult to study due to the poorly infectious nature of HTLV-1 and the need for cell-to-cell contact for HTLV-1 transmission. Using a series of reporter systems, we show that HeLa cells cease proliferation within one or two division cycles after infection by HTLV-1 or transduction of the HTLV-1 tax gene. HTLV-1-infected HeLa cells, like their tax-transduced counterparts, expressed high levels of p21(CIP1/WAF1) and p27(KIP1), developed mitotic abnormalities, and became arrested in G(1) in senescence. In contrast, cells of a human osteosarcoma lineage (HOS) continued to divide after HTLV-1 infection or Tax expression, albeit at a reduced growth rate and with mitotic aberrations. Unique to HOS cells is the dramatic reduction of p21(CIP1/WAF1) and p27(KIP1) expression, which is in part associated with the constitutive activation of the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt) pathway. The loss of p21(CIP1/WAF1) and p27(KIP1) in HOS cells apparently allows HTLV-1- and Tax-induced G(1) arrest to be bypassed. Finally, HTLV-1 infection and Tax expression also cause human SupT1 T cells to arrest in the G(1) phase of the cell cycle. These results suggest that productive HTLV-1 infection ordinarily leads to Tax-mediated G(1) arrest. However, T cells containing somatic mutations that inactivate p21(CIP1/WAF1) and p27(KIP1) may continue to proliferate after HTLV-1 infection and Tax expression. These infected cells can expand clonally, accumulate additional chromosomal abnormalities, and progress to cancer.
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Sinha-Datta U, Taylor JM, Brown M, Nicot C. Celecoxib disrupts the canonical apoptotic network in HTLV-I cells through activation of Bax and inhibition of PKB/Akt. Apoptosis 2008; 13:33-40. [PMID: 17952603 DOI: 10.1007/s10495-007-0148-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Adult T-cell leukemia/lymphoma (ATLL) is an aggressive lymphoproliferative disease of very poor clinical prognosis associated with infection by the human T-cell leukemia virus type I (HTLV-I). Treatment of patients with ATLL using conventional chemotherapy has limited benefit because HTLV-I cells are refractory to most apoptosis-inducing agents. In this study, we report that Celecoxib induces cell death via the intrinsic mitochondrial pathway in HTLV-I transformed leukemia cells. Treatment with Celecoxib was associated with activation of Bax, decreased expression of Mcl-1, loss of the mitochondrial membrane potential and caspase-9-dependent apoptosis. These effects were independent from Bcl-2 and Bcl-xL. We also found that Celecoxib inhibited the Akt/GSK3 beta survival pathway in HTLV-I cells.
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Affiliation(s)
- Uma Sinha-Datta
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160, USA
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Tomita M, Semenza G, Michiels C, Matsuda T, Uchihara JN, Okudaira T, Tanaka Y, Taira N, Ohshiro K, Mori N. Activation of hypoxia-inducible factor 1 in human T-cell leukaemia virus type 1-infected cell lines and primary adult T-cell leukaemia cells. Biochem J 2007; 406:317-23. [PMID: 17576198 PMCID: PMC1948965 DOI: 10.1042/bj20070286] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
HTLV-1 (human T-cell leukaemia virus type 1) is the causative agent for ATL (adult T-cell leukaemia). HTLV-1 Tax can activate the PI3K (phosphoinositide 3-kinase)/Akt signalling pathway, which is responsible for survival of HTLV-1-infected T-cells. HIFs (hypoxia-inducible factors) are transcriptional regulators that play a central role in the response to hypoxia. Overexpression of HIF-1alpha in many cancers is associated with a poor response to treatment and increased patient mortality. Our objectives in the present study were to investigate whether HIF-1 was activated in HTLV-1-infected T-cells and to elucidate the molecular mechanisms of HIF-1 activation by focusing on the PI3K/Akt signalling pathway. We detected a potent pathway that activated HIF-1 in the HTLV-1-infected T-cells under a normal oxygen concentration. Enhanced HIF-1alpha protein expression and HIF-1 DNA-binding activity were exhibited in HTLV-1-infected T-cell lines. Knockdown of HIF-1alpha by siRNA (small interfering RNA) suppressed the growth and VEGF (vascular endothelial growth factor) expression of the HTLV-1-infected T-cell line. HIF-1 protein accumulation and transcriptional activity were enhanced by Tax, which was inhibited by dominant-negative Akt. Importantly, mutant forms of Tax that are defective in activation of the PI3K/Akt pathway failed to induce HIF-1 transcriptional activity. The PI3K inhibitor LY294002 suppressed HIF-1alpha protein expression, HIF-1 DNA-binding and HIF-1 transcriptional activity in HTLV-1-infected T-cell lines. In primary ATL cells, HIF-1alpha protein levels were strongly correlated with levels of phosphorylated Akt. The results of the present study suggest that PI3K/Akt activation induced by Tax leads to activation of HIF-1. As HIF-1 plays a major role in tumour progression, it may represent a molecular target for the development of novel ATL therapeutics.
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Affiliation(s)
- Mariko Tomita
- *Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan
| | - Gregg L. Semenza
- †The Johns Hopkins University School of Medicine, Broadway Research Building, Suite 671, 733 N Broadway, Baltimore, MD 21205, U.S.A
| | - Canine Michiels
- ‡Laboratoire de Biochimie et Biologie Cellulaire, University of Namur, 51 Rue de Bruxelles, Namur 5000, Belgium
| | - Takehiro Matsuda
- *Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan
- §Division of Child Health and Welfare, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan
| | - Jun-Nosuke Uchihara
- *Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan
- ∥Division of Endocrinology and Metabolism, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan
| | - Taeko Okudaira
- *Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan
- ∥Division of Endocrinology and Metabolism, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan
| | - Yuetsu Tanaka
- ¶Division of Immunology, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan
| | - Naoya Taira
- **Department of Hematology, Heartlife Hospital, 208 Ijyu, Nakagusuku 901-2492, Japan
| | - Kazuiku Ohshiro
- ††Department of Hematology, Okinawa Prefectural Nanbu Medical Center and Children's Medical Center, 118-1 Arakawa, Haebaru 901-1193, Japan
| | - Naoki Mori
- *Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara 903-0215, Japan
- To whom correspondence should be addressed (email )
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Kawakami H, Tomita M, Okudaira T, Ishikawa C, Matsuda T, Tanaka Y, Nakazato T, Taira N, Ohshiro K, Mori N. Inhibition of heat shock protein-90 modulates multiple functions required for survival of human T-cell leukemia virus type I-infected T-cell lines and adult T-cell leukemia cells. Int J Cancer 2007; 120:1811-20. [PMID: 17230513 DOI: 10.1002/ijc.22403] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The molecular chaperone Hsp90 is involved in the stabilization and conformational maturation of many signaling proteins that are deregulated in cancers. The geldanamycin derivative 17-AAG is currently tested in clinical trials and known to inhibit the function of Hsp90 and promote the proteasomal degradation of its misfolded client proteins. ATL is a fatal malignancy of T lymphocytes caused by HTLV-I infection and remains incurable. Since Hsp90 is overexpressed in HTLV-I-infected T-cell lines and primary ATL cells, we analyzed the effects of 17-AAG on cell survival, apoptosis and expression of signal transduction proteins. HTLV-I-infected T-cell lines and primary ATL cells were significantly more sensitive to 17-AAG in cell survival assays than normal PBMCs. 17-AAG induced the inhibition of cell cycle and apoptosis. These effects could be mediated by inactivation of NF-kappaB, AP-1 and PI3K/Akt pathways, as well as reduction of expression of proteins involved in the G1-S cell cycle transition and apoptosis. Proteasome inhibition interfered with 17-AAG-mediated signaling proteins depletion. Collectively, our results indicate that 17-AAG suppresses ATL cell survival through, at least in part, destabilization of several client proteins and suggest that 17-AAG is a potentially useful chemotherapeutic agent for ATL.
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Affiliation(s)
- Hirochika Kawakami
- Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Japan
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Akl H, Badran BM, Zein NE, Zein NE, Bex F, Sotiriou C, Willard-Gallo KE, Burny A, Martiat P. HTLV-I infection of WE17/10 CD4+ cell line leads to progressive alteration of Ca2+ influx that eventually results in loss of CD7 expression and activation of an antiapoptotic pathway involving AKT and BAD which paves the way for malignant transformation. Leukemia 2007; 21:788-96. [PMID: 17287851 DOI: 10.1038/sj.leu.2404585] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Adult T-cell leukemia/lymphoma (ATLL) is a malignancy slowly emerging from human T-cell leukemia virus type 1 (HTLV-I)-infected mature CD4(+) T-cells. To characterize the molecular modifications induced by HTLV-I infection, we compared HTLV-I-infected WE17/10 cells with control cells, using micro-arrays. Many calcium-related genes were progressively downmodulated over a period of 2 years. Infected cells acquired a profound decrease of intracellular calcium levels in response to ionomycin, timely correlated with decreased CD7 expression. Focusing on apoptosis-related genes and their relationship with CD7, we observed an underexpression of most antiapoptotic genes. Western blotting revealed increasing Akt and Bad phosphorylation, timely correlated with CD7 loss. This was shown to be phosphatidylinositol 3-kinase (PI3K)-dependent. Activation of PI3K/Akt induced resistance to the apoptotic effect of interleukin-2 deprivation. We thus propose the following model: HTLV-I infection induces a progressive decrease in CD3 genes expression, which eventually abrogates CD3 expression; loss of CD3 is known to perturb calcium transport. This perturbation correlates with loss of CD7 expression and induction of Akt and Bad phosphorylation via activation of PI3K. The activation of the Akt/Bad pathway generates a progressive resistance to apoptosis, at a time HTLV-I genes expression is silenced, thus avoiding immune surveillance. This could be a major event in the process of the malignant transformation into ATLL.
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Affiliation(s)
- H Akl
- Laboratory of Experimental Hematology, Bordet Institute, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium
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Chugh P, Fan S, Planelles V, Maggirwar SB, Dewhurst S, Kim B. Infection of human immunodeficiency virus and intracellular viral Tat protein exert a pro-survival effect in a human microglial cell line. J Mol Biol 2006; 366:67-81. [PMID: 17157319 PMCID: PMC7127718 DOI: 10.1016/j.jmb.2006.11.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2006] [Revised: 10/31/2006] [Accepted: 11/02/2006] [Indexed: 02/07/2023]
Abstract
The interaction of human immunodeficiency virus type 1 (HIV-1) with CD4+ T lymphocytes is well studied and typically results in virally induced cytolysis. In contrast, relatively little is known concerning the interplay between HIV-1 and microglia. Recent findings suggest that, counter-intuitively, HIV-1 infection may extend the lifespan of microglia. We developed a novel cell line model system to confirm and mechanistically study this phenomenon. We found that transduction of a human microglial cell line with an HIV-1 vector results in a powerful cytoprotective effect following apoptotic challenge. This effect was reproduced by ectopic expression of a single virus-encoded protein, Tat. Subsequent studies showed that the pro-survival effects of intracellular Tat could be attributed to activation of the PI-3-kinase (PI3K)/Akt pathway in the microglial cell line. Furthermore, we found that expression of Tat led to decreased expression of PTEN, a negative regulator of the PI-3-K pathway. Consistent with this, decreased p53 activity and increased E2F activity were observed. Based on these findings, a model of possible regulatory circuits that intracellular Tat and HIV-1 infection engage during the cytoprotective event in microglia has been suggested. We propose that the expression of Tat may enable HIV-1 infected microglia to survive throughout the course of infection, leading to persistent HIV-1 production and infection in the central nervous system.
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Affiliation(s)
- Pauline Chugh
- Department of Microbiology and Immunology, School of Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Box 672, Rochester, NY 14742, USA
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Brown M, Bellon M, Nicot C. Emodin and DHA potently increase arsenic trioxide interferon-alpha-induced cell death of HTLV-I-transformed cells by generation of reactive oxygen species and inhibition of Akt and AP-1. Blood 2006; 109:1653-9. [PMID: 17077332 PMCID: PMC1794054 DOI: 10.1182/blood-2006-04-015537] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Adult T-cell leukemia (ATL) is an aggressive lymphoproliferative disease of poor clinical prognosis associated with infection by the human T-cell leukemia virus type I (HTLV-I). The use of arsenic trioxide (As2O3) has been shown to effectively treat acute promyelocytic leukemia (APL) with greater than 80% of patients achieving complete remission. The combination of arsenic and interferon has also shown promising results in the treatment of ATL. The requirement for slow dosage increases of arsenic and the time required to achieve a pharmacologic active dose in patients is a major obstacle because median survival of patients with ATL is about 6 months. In this study we report a potent synergistic effect of the combination of arsenic trioxide and interferon alpha (As/IFN-alpha) with emodin and DHA on cell-cycle arrest and cell death of HTLV-I-infected cells. Importantly, we found that clinically achievable doses of DHA and emodin allowed for reduced arsenic concentrations by 100-fold while still remaining highly toxic to tumor cells. Our data provide a rationale for combined use of As/IFN-alpha with emodin and DHA in patients with ATL refractory to conventional therapy.
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Affiliation(s)
- Megan Brown
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kansas Medical Center, Kansas City 66160, USA
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37
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Ikezoe T, Nishioka C, Bandobashi K, Yang Y, Kuwayama Y, Adachi Y, Takeuchi T, Koeffler HP, Taguchi H. Longitudinal inhibition of PI3K/Akt/mTOR signaling by LY294002 and rapamycin induces growth arrest of adult T-cell leukemia cells. Leuk Res 2006; 31:673-82. [PMID: 17007924 DOI: 10.1016/j.leukres.2006.08.001] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 07/17/2006] [Accepted: 08/02/2006] [Indexed: 01/23/2023]
Abstract
This study found that phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling was activated in human T-cell lymphotropic virus type I (HTLV-1)-infected leukemia cells. Rapamycin (1-100 nM, 48h), the inhibitor of mTOR and its analog RAD001 (1-100 nM, 48 h)-induced growth inhibition and G0/G1 cell cycle arrest of these cells in association with de-phosphorylation of p70S6K and 4E-BP-1, although IC50 was not achieved. Paradoxically, rapamycin-stimulated phosphorylation of Akt at Ser473. Blockade of Akt signaling by the PI3K inhibitor LY294002 (1-20 microM, 48 h) also resulted in the growth inhibition and G0/G1 cell cycle arrest of HTLV-1-infected cells, with IC50 ranging from 5 to 20muM, and it caused de-phosphorylation of p70S6K and 4E-BP-1. Of note, when rapamycin was combined with LY294002, rapamycin-induced phosphorylation of Akt was blocked, and the ability of rapamycin to induce growth arrest of HTLV-1-infected T-cells and suppress the p-p70S6K and p-4E-BP-1 proteins was potentiated. Moreover, both LY294002 and rapamycin down-regulated the levels of c-Myc and cyclin D1 proteins in these cells, and their combination further decreased levels of these cell cycle-regulating proteins. Taken together, longitudinal inhibition of PI3K/Akt/mTOR signaling represents a promising treatment strategy for individuals with adult T-cell leukemia.
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Affiliation(s)
- Takayuki Ikezoe
- Department of Hematology and Respiratory Medicine, Kochi University, Nankoku, Kochi 783-8505, Japan.
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38
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Tomita M, Kikuchi A, Akiyama T, Tanaka Y, Mori N. Human T-cell leukemia virus type 1 tax dysregulates beta-catenin signaling. J Virol 2006; 80:10497-505. [PMID: 16920823 PMCID: PMC1641756 DOI: 10.1128/jvi.00739-06] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dysregulation of beta-catenin signaling has been implicated in the malignant transformation of cells. However, the role of beta-catenin in the human T-cell leukemia virus type 1 (HTLV-1)-induced transformation of T cells is unknown. Here we found that beta-catenin protein was overexpressed in the nucleus and that beta-catenin-dependent transcription was significantly enhanced in Tax-positive HTLV-1-infected T-cell lines compared to that in Tax-negative HTLV-1-infected T-cell lines. Transfection with beta-catenin-specific small interfering RNA inhibited the growth of the Tax-positive HTLV-1-infected T-cell line HUT-102. Transient transfection of Tax appeared to enhance beta-catenin-dependent transcription by stabilizing the beta-catenin protein via activation of the cyclic AMP (cAMP) response element-binding protein. HTLV-1-infected T-cell lines overexpressing beta-catenin also showed increased Akt activity via Tax activation of the cAMP response element-binding protein, resulting in the phosphorylation and inactivation of glycogen synthase kinase 3beta, which phosphorylates beta-catenin for ubiquitination. The phosphatidylinositol 3-kinase inhibitor LY294002 reduced beta-catenin expression in Tax-positive T-cell lines, and inactivation of glycogen synthase kinase 3beta by lithium chloride restored beta-catenin expression in Tax-negative T-cell lines. Finally, we showed that dominant-negative Akt inhibited Tax-induced beta-catenin-dependent transcription. These results indicate that Tax activates beta-catenin through the Akt signaling pathway. Our findings suggest that activation of beta-catenin by Tax may be important in the transformation of T cells by HTLV-1 infection.
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Affiliation(s)
- Mariko Tomita
- Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan
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Tomita M, Matsuda T, Kawakami H, Uchihara JN, Okudaira T, Masuda M, Ohshiro K, Mori N. Curcumin targets Akt cell survival signaling pathway in HTLV-I-infected T-cell lines. Cancer Sci 2006; 97:322-7. [PMID: 16630125 PMCID: PMC11159354 DOI: 10.1111/j.1349-7006.2006.00175.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Akt signaling pathway is important for survival and growth of cancer cells. In the present paper we show that the Akt signaling pathway is constitutively activated in human T-cell leukemia virus type I (HTLV-I)-infected T-cell lines and in primary adult T-cell leukemia (ATL) cells. Curcumin, a natural compound present in turmeric, has been studied vigorously as a potent chemopreventive agent for cancer therapy because of its inhibitory effect on proliferation and induction of apoptosis in several tumor cell lines. We investigated the effect of curcumin on Akt activity in HTLV-I-infected T-cell lines and primary ATL cells. Phosphorylated PDK1 is an activator of Akt by phosphorylating Akt. Curcumin reduced phosphorylation of PDK1 and inhibited constitutive activation of Akt. Curcumin activated glycogen synthase kinase (GSK)-3beta, a downstream target of Akt kinase, by inhibiting phosphorylation of this protein. Curcumin reduced the expression of cell cycle regulators, cyclin D1 and c-Myc proteins, which are both degraded by activated GSK-3beta. Our results suggest that activation of the Akt signaling pathway plays an important role in ATL cell survival, and that curcumin may have anti-ATL properties mediated, at least in part, by inhibiting Akt activity. We propose that Akt-targeting agents could be useful for the treatment of ATL. In this regard, curcumin is a potentially promising compound for the treatment of ATL.
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Affiliation(s)
- Mariko Tomita
- Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan
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40
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Frese KK, Latorre IJ, Chung SH, Caruana G, Bernstein A, Jones SN, Donehower LA, Justice MJ, Garner CC, Javier RT. Oncogenic function for the Dlg1 mammalian homolog of the Drosophila discs-large tumor suppressor. EMBO J 2006; 25:1406-17. [PMID: 16511562 PMCID: PMC1422156 DOI: 10.1038/sj.emboj.7601030] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Accepted: 02/08/2006] [Indexed: 12/30/2022] Open
Abstract
The fact that several different human virus oncoproteins, including adenovirus type 9 E4-ORF1, evolved to target the Dlg1 mammalian homolog of the membrane-associated Drosophila discs-large tumor suppressor has implicated this cellular factor in human cancer. Despite a general belief that such interactions function solely to inactivate this suspected human tumor suppressor protein, we demonstrate here that E4-ORF1 specifically requires endogenous Dlg1 to provoke oncogenic activation of phosphatidylinositol 3-kinase (PI3K) in cells. Based on our results, we propose a model wherein E4-ORF1 binding to Dlg1 triggers the resulting complex to translocate to the plasma membrane and, at this site, to promote Ras-mediated PI3K activation. These findings establish the first known function for Dlg1 in virus-mediated cellular transformation and also surprisingly expose a previously unrecognized oncogenic activity encoded by this suspected cellular tumor suppressor gene.
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Affiliation(s)
- Kristopher K Frese
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Isabel J Latorre
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Sang-Hyuk Chung
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Georgina Caruana
- Department of Anatomy and Cell Biology, Monash University, Clayton, Victoria, Australia
| | - Alan Bernstein
- Program in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Stephen N Jones
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Lawrence A Donehower
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Monica J Justice
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Craig C Garner
- Department of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, CA, USA
| | - Ronald T Javier
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA. Tel.: +1 713 798 3898; Fax: +1 713 798 3586; E-mail:
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Peloponese JM, Jeang KT. Role for Akt/Protein Kinase B and Activator Protein-1 in Cellular Proliferation Induced by the Human T-cell Leukemia Virus Type 1 Tax Oncoprotein. J Biol Chem 2006; 281:8927-38. [PMID: 16436385 DOI: 10.1074/jbc.m510598200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Human T-cell leukemia virus type 1 is an oncogenic retrovirus etiologically causal of adult T-cell leukemia. The virus encodes a Tax oncoprotein, which functions in transcriptional regulation, cell cycle control, and transformation. Because adult T-cell leukemia is a highly virulent cancer that is resistant to numerous chemotherapeutic treatments, to understand better this disease it is important to comprehend how human T-cell leukemia virus type 1 promotes cellular growth and survival. Most of the existing data point to Tax activation of NF-kappaB as important for cellular proliferation and transformation. We show here that Tax, in the absence of NF-kappaB signaling, can activate activator protein-1 to promote cellular proliferation and survival. Tax is shown to activate activator protein-1 through the phosphatidylinositol 3-kinase/Akt pathway.
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Affiliation(s)
- Jean-Marie Peloponese
- Molecular Virology Section, Laboratory of Molecular Microbiology, NIAID, National Institutes of Health, Bethesda, Maryland 20892-0460, USA
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42
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Varela M, Chow YH, Sturkie C, Murcia P, Palmarini M. Association of RON tyrosine kinase with the Jaagsiekte sheep retrovirus envelope glycoprotein. Virology 2006; 350:347-57. [PMID: 16500691 DOI: 10.1016/j.virol.2006.01.040] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 01/06/2006] [Accepted: 01/26/2006] [Indexed: 01/21/2023]
Abstract
The envelope (Env) of Jaagsiekte sheep retrovirus (JSRV) functions as an oncoprotein. One of the mechanisms of JSRV-induced cell transformation that has been proposed for epithelial cells involves JSRV Env binding Hyaluronidase 2 (the JSRV receptor), thereby inducing its degradation and allowing the release and activation of RON tyrosine kinase which is normally suppressed by HYAL-2. In this study, we report that HYAL-2 and RON are not critical for the JSRV Env-induced transformation of the rat epithelial cell line IEC-18, while the cytoplasmic tail of the JSRV Env is critical to transform this cell line. We have also determined that RON can associate with the JSRV Env under normal and stringent conditions. In addition, the cytoplasmic tail of the JSRV and the enJS5F16 (non oncogenic JSRV-related endogenous retrovirus) Env proteins appears to have a major influence on the activation status of RON. Thus, it appears that the interaction of the JSRV Env with RON is more complex than previously thought and requires further investigation.
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Affiliation(s)
- Mariana Varela
- Institute of Comparative Medicine, University of Glasgow Veterinary School, 464 Bearsden Road, Glasgow G61 1QH, UK
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Arnold J, Yamamoto B, Li M, Phipps AJ, Younis I, Lairmore MD, Green PL. Enhancement of infectivity and persistence in vivo by HBZ, a natural antisense coded protein of HTLV-1. Blood 2006; 107:3976-82. [PMID: 16424388 PMCID: PMC1895283 DOI: 10.1182/blood-2005-11-4551] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Natural antisense viral transcripts have been recognized in retroviruses, including human T-cell leukemia virus type 1 (HTLV-1), HIV-1, and feline immunodeficiency virus (FIV), and have been postulated to encode proteins important for the infection cycle and/or pathogenesis of the virus. The antisense strand of the HTLV-1 genome encodes HBZ, a novel nuclear basic region leucine zipper (b-ZIP) protein that in overexpression assays down-regulates Tax oncoprotein-induced viral transcription. Herein, we investigated the contribution of HBZ to HTLV-1-mediated immortalization of primary T lymphocytes in vitro and HTLV-1 infection in a rabbit animal model. HTLV-1 HBZ mutant viruses were generated and evaluated for viral gene expression, protein production, and immortalization capacity. Biologic properties of HBZ mutant viruses in vitro were indistinguishable from wild-type HTLV-1, providing the first direct evidence that HBZ is dispensable for viral replication and cellular immortalization. Rabbits inoculated with irradiated cells expressing HTLV-1 HBZ mutant viruses became persistently infected. However, these rabbits displayed a decreased antibody response to viral gene products and reduced proviral copies in peripheral blood mononuclear cells (PBMCs) as compared with wild-type HTLV-1-infected animals. Our findings indicated that HBZ was not required for in vitro cellular immortalization, but enhanced infectivity and persistence in inoculated rabbits. This study demonstrates that retroviruses use negative-strand-encoded proteins in the establishment of chronic viral infections.
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Affiliation(s)
- Joshua Arnold
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA
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Rajasingh J, Raikwar HP, Muthian G, Johnson C, Bright JJ. Curcumin induces growth-arrest and apoptosis in association with the inhibition of constitutively active JAK-STAT pathway in T cell leukemia. Biochem Biophys Res Commun 2005; 340:359-68. [PMID: 16364242 DOI: 10.1016/j.bbrc.2005.12.014] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Accepted: 12/02/2005] [Indexed: 02/08/2023]
Abstract
Adult T cell leukemia is an aggressive and frequently fatal malignancy that expressess constitutively activated growth-signaling pathways in association with deregulated growth and resistance to apoptosis. Curcumin (diferuloylmethane) is a naturally occurring yellow pigment, isolated from the rhizomes of the plant Curcuma longa that has traditionally been used in the treatment of injury and inflammation. But the effect and mechanism of action of curcumin on T cell leukemia is not known. To investigate the antitumor activity of curcumin in T cell leukemia, we examined its effect on constitutive phosphorylation of JAK and STAT proteins, proliferation, and apoptosis in HTLV-I-transformed T cell lines. HTLV-I-transformed T cell leukemia lines, MT-2, HuT-102, and SLB-1, express constitutively phosphorylated JAK3, TYK2, STAT3, and STAT5 signaling proteins. In vitro treatment with curcumin induced a dose-dependent decrease in JAK and STAT phosphorylation resulting in the induction of growth-arrest and apoptosis in T cell leukemia. The induction of growth-arrest and apoptosis in association with the blockade of constitutively active JAK-STAT pathway suggests this be a mechanism by which curcumin induces antitumor activity in T cell leukemia.
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Affiliation(s)
- Johnson Rajasingh
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, USA
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Abstract
DNA viruses have enormous utility in cancer research, both as tools for tumor target discovery as well as agents for lytic cancer therapies. This is because there is a profound functional overlap between the DNA viral and tumor cell programs. DNA viruses encode proteins that elicit growth deregulation in infected cells similar to that engendered by mutations in tumor cells. Evolution has refined viral proteins to target the critical cellular hubs that regulate growth. Thus, viral proteins are discriminating biochemical probes that can be used to identify and characterize novel tumor targets. Moreover, the overlap between the DNA viral and tumor programs can also be exploited for the development of lytic cancer therapies. Discovering whether tumor cells selectively complement the replication of viral mutants can reveal novel oncolytic viral therapies, as well as unexpected tumor properties. For example, altered RNA export was recently uncovered as a novel tumor cell property that underlies ONYX-015 replication, a promising oncolytic adenoviral therapy. A perspective is provided on how adenovirus could be systematically exploited to map the requisite role, or indeed the redundancy, of cellular pathways that act in an integrated program to elicit pathological replication. This knowledge has important applications for the rational design of the next generation of oncolytic viruses, as well as the discovery of efficacious combination cancer therapies.
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Affiliation(s)
- Clodagh C O'Shea
- Cancer Research Institute, University of California San Francisco, 94115, USA.
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Jeong SJ, Pise-Masison CA, Radonovich MF, Park HU, Brady JN. Activated AKT regulates NF-kappaB activation, p53 inhibition and cell survival in HTLV-1-transformed cells. Oncogene 2005; 24:6719-28. [PMID: 16007163 DOI: 10.1038/sj.onc.1208825] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
AKT activation enhances resistance to apoptosis and induces cell survival signaling through multiple downstream pathways. We now present evidence that AKT is activated in HTLV-1-transformed cells and that Tax activation of AKT is linked to NF-kappaB activation, p53 inhibition and cell survival. Overexpression of AKT wild type (WT), but not a kinase dead (KD) mutant, resulted in increased Tax-mediated NF-kappaB activation. Blocking AKT with the PI3K/AKT inhibitor LY294002 or AKT SiRNA prevented NF-kappaB activation and inhibition of p53. Treatment of C81 cells with LY294002 resulted in an increase in the p53-responsive gene MDM2, suggesting a role for AKT in the Tax-mediated regulation of p53 transcriptional activity. Further, we show that LY294002 treatment of C81 cells abrogates in vitro IKKbeta phosphorylation of p65 and causes a reduction of p65 Ser-536 phosphorylation in vivo, steps critical to p53 inhibition. Interestingly, blockage of AKT function did not affect IKKbeta phosphorylation of IkappaBalpha in vitro suggesting selective activity of AKT on the IKKbeta complex. Finally, AKT prosurvival function in HTLV-1-transformed cells is linked to expression of Bcl-xL. We suggest that AKT plays a role in the activation of prosurvival pathways in HTLV-1-transformed cells, possibly through NF-kappaB activation and inhibition of p53 transcription activity.
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Affiliation(s)
- Soo-Jin Jeong
- Virus Tumor Biology Section, Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-5055, USA
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Abstract
Human T-lymphotropic virus type 1 (HTLV-1) infection is associated with the clonal expansion and transformation of mature T lymphocytes. While the mechanisms involved are incompletely understood the viral regulatory protein Tax plays a central role in these processes. Recent studies employing genomic and proteomic approaches have demonstrated the marked complexity of gene deregulation associated with Tax expression and confirmed the remarkable pleiotropism of this protein as evidenced by the numerous Tax-cellular protein interactions in infected cells. In this review, we summarize the role of Tax in the deregulation of selected cellular-signaling pathways. Specifically, this has focused on the influence and interaction of Tax with the AP-1 and NF-AT transcription factors, PDZ domain-containing proteins, Rho-GTPases, and the Janus kinase/signal transducer and activator of transcription and transforming growth factor-beta-signaling pathways. In addition to identifying the deregulation of events within these pathways, attempts have been made to highlight differences between HTLV-1 and -2, which may relate to differences in their pathogenic properties.
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Affiliation(s)
- William W Hall
- Department of Medical Microbiology, Centre for Research in Infectious Diseases, University College Dublin, Belfield, Dublin 4, Ireland.
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Abstract
The HTLV Tax protein is crucial for viral replication and for initiating malignant transformation leading to the development of adult T-cell leukemia. Tax has been shown to be oncogenic, since it transforms and immortalizes rodent fibroblasts and human T-lymphocytes. Through CREB, NF-kappaB and SRF pathways Tax transactivates cellular promoters including those of cytokines (IL-13, IL-15), cytokine receptors (IL-2Ralpha) and costimulatory surface receptors (OX40/OX40L) leading to upregulated protein expression and activated signaling cascades (e.g. Jak/STAT, PI3Kinase, JNK). Tax also stimulates cell growth by direct binding to cyclin-dependent kinase holenzymes and/or inactivating tumor suppressors (e.g. p53, DLG). Moreover, Tax silences cellular checkpoints, which guard against DNA structural damage and chromosomal missegregation, thereby favoring the manifestation of a mutator phenotype in cells.
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Affiliation(s)
- Ralph Grassmann
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schlossgarten 4, Germany.
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Matsuda T, Almasan A, Tomita M, Uchihara JN, Masuda M, Ohshiro K, Takasu N, Yagita H, Ohta T, Mori N. Resistance to Apo2 ligand (Apo2L)/tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis and constitutive expression of Apo2L/TRAIL in human T-cell leukemia virus type 1-infected T-cell lines. J Virol 2005; 79:1367-78. [PMID: 15650163 PMCID: PMC544134 DOI: 10.1128/jvi.79.3.1367-1378.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Adult T-cell leukemia (ATL), a CD4+-T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1), is difficult to cure, and novel treatments are urgently needed. Apo2 ligand (Apo2L; also tumor necrosis factor-related apoptosis-inducing ligand [TRAIL]) has been implicated in antitumor therapy. We found that HTLV-1-infected T-cell lines and primary ATL cells were more resistant to Apo2L-induced apoptosis than uninfected cells. Interestingly, HTLV-1-infected T-cell lines and primary ATL cells constitutively expressed Apo2L mRNA. Inducible expression of the viral oncoprotein Tax in a T-cell line up-regulated Apo2L mRNA. Analysis of the Apo2L promoter revealed that this gene is activated by Tax via the activation of NF-kappaB. The sensitivity to Apo2L was not correlated with expression levels of Apo2L receptors, intracellular regulators of apoptosis (FLICE-inhibitory protein and active Akt). NF-kappaB plays a crucial role in the pathogenesis and survival of ATL cells. The resistance to Apo2L-induced apoptosis was reversed by N-acetyl-L-leucinyl-L-leucinyl-lLnorleucinal (LLnL), an NF-kappaB inhibitor. LLnL significantly induced the Apo2L receptors DR4 and DR5. Our results suggest that the constitutive activation of NF-kappaB is essential for Apo2L gene induction and protection against Apo2L-induced apoptosis and that suppression of NF-kappaB may be a useful adjunct in clinical use of Apo2L against ATL.
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Affiliation(s)
- Takehiro Matsuda
- Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan
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Sieburg M, Tripp A, Ma JW, Feuer G. Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 tax oncoproteins modulate cell cycle progression and apoptosis. J Virol 2004; 78:10399-409. [PMID: 15367606 PMCID: PMC516438 DOI: 10.1128/jvi.78.19.10399-10409.2004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2003] [Accepted: 05/25/2004] [Indexed: 11/20/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia and lymphoma, an aggressive clonal malignancy of human CD4-bearing T lymphocytes. HTLV-2, although highly related to HTLV-1 at the molecular level, has not been conclusively linked to development of lymphoproliferative disorders. Differences between the biological activities of the respective tax gene products (Tax1 and Tax2) may be one factor which accounts for the differential pathogenicities associated with infection. To develop an in vitro model to investigate and compare the effects of constitutive expression of Tax1 and Tax2, Jurkat T-cell lines were infected with lentivirus vectors encoding Tax1 and Tax2 in conjunction with green fluorescent protein, and stably transduced clonal cell lines were generated by serial dilution in the absence of drug selection. Jurkat cells that constitutively express Tax1 and Tax2 (Tax1/Jurkat and Tax2/Jurkat, respectively) showed notably reduced kinetics of cellular replication, and Tax1 inhibited cellular replication to a higher degree in comparison to Tax2. Tax1 markedly activated transcription from the cdk inhibitor p21(cip1/waf1) promoter in comparison to Tax2, suggesting that upregulation of p21(cip1/waf1) may account for the differential inhibition of cellular replication kinetics displayed by Tax1/Jurkat and Tax2/Jurkat cells. The presence of binucleated and multinucleated cells, reminiscent of large lymphocytes with cleaved or cerebriform nuclei often seen in HTLV-1- and -2-seropositive patients, was noted in cultures expressing Tax1 and Tax2. Although Tax1 and Tax2 expression mediated elevated resistance to apoptosis in Jurkat cells after serum deprivation, Tax1 was unique in protection from apoptosis after exposure to camptothecin and etoposide, inhibitors of topoisomerase I and II, respectively. Characterization of the unique phenotypes displayed by Tax1 and Tax2 in vitro will provide information as to the relative roles of these oncoproteins and their contribution to HTLV-1 and -2 pathogenesis in vivo.
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Affiliation(s)
- Michelle Sieburg
- SUNY Upstate Medical University, Department of Microbiology and Immunology, 750 East Adams St., Syracuse, NY 13210, USA
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