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Li W, Hu JK, Hu MG. CDK6: an attractive therapeutic target for T-ALL/LBL. Expert Opin Ther Targets 2023; 27:1087-1096. [PMID: 37975616 DOI: 10.1080/14728222.2023.2285775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 11/16/2023] [Indexed: 11/19/2023]
Abstract
INTRODUCTION Human T-cell acute lymphoblastic leukemia/T-cell lymphoblastic lymphoma (T-ALL/LBL) is a type of cancer that originates from the bone marrow and spreads quickly to other organs. Long-term survival rate with current available chemotherapy is less than 20%. Despite the potentially huge market, a truly effective and safe therapy for T-ALL/LBL is elusive. Thus, it is imperative to identify new therapeutic ways to target essential pathways in T-ALL that regulate the proliferation and survival of these cancer cells. AREAS COVERED The role of the Cyclin-dependent kinase 6 (CDK6) pathway in human T-ALL is of significant interest with major clinical/translational relevance. This review covers the recent advances in elucidating the essential roles of CDK6 and its closely regulated networks in proliferation, survival, and metabolism of T-ALL cells, with new insight into its mechanisms of action which hopefully could trigger the identification of new therapeutic avenues. EXPERT OPINION Animal models showed that inhibition of CDK6 and its related networks blocked initiation, growth, and survival of T-ALL in vivo. Numerous clinical trials of CDK4/6 inhibitors are ongoing in T-ALL. Specific CDK6 inhibitors alone or novel combination regimens may hopefully delay the progression, or even reverse the symptoms of T-ALL, leading to disease eradication and cure.
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Affiliation(s)
- Wei Li
- Department of Medicine, Division of Hematology and Oncology, Tufts Medical Center, Boston, USA
| | - Jamie Katy Hu
- Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Miaofen G Hu
- Department of Medicine, Division of Hematology and Oncology, Tufts Medical Center, Boston, USA
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Watanabe T. Adult T-cell leukemia: molecular basis for clonal expansion and transformation of HTLV-1-infected T cells. Blood 2017; 129:1071-1081. [PMID: 28115366 PMCID: PMC5374731 DOI: 10.1182/blood-2016-09-692574] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 12/21/2016] [Indexed: 02/07/2023] Open
Abstract
Adult T-cell leukemia (ATL) is an aggressive T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1) that develops through a multistep carcinogenesis process involving 5 or more genetic events. We provide a comprehensive overview of recently uncovered information on the molecular basis of leukemogenesis in ATL. Broadly, the landscape of genetic abnormalities in ATL that include alterations highly enriched in genes for T-cell receptor-NF-κB signaling such as PLCG1, PRKCB, and CARD11 and gain-of function mutations in CCR4 and CCR7 Conversely, the epigenetic landscape of ATL can be summarized as polycomb repressive complex 2 hyperactivation with genome-wide H3K27 me3 accumulation as the basis of the unique transcriptome of ATL cells. Expression of H3K27 methyltransferase enhancer of zeste 2 was shown to be induced by HTLV-1 Tax and NF-κB. Furthermore, provirus integration site analysis with high-throughput sequencing enabled the analysis of clonal composition and cell number of each clone in vivo, whereas multicolor flow cytometric analysis with CD7 and cell adhesion molecule 1 enabled the identification of HTLV-1-infected CD4+ T cells in vivo. Sorted immortalized but untransformed cells displayed epigenetic changes closely overlapping those observed in terminally transformed ATL cells, suggesting that epigenetic abnormalities are likely earlier events in leukemogenesis. These new findings broaden the scope of conceptualization of the molecular mechanisms of leukemogenesis, dissecting them into immortalization and clonal progression. These recent findings also open a new direction of drug development for ATL prevention and treatment because epigenetic marks can be reprogrammed. Mechanisms underlying initial immortalization and progressive accumulation of these abnormalities remain to be elucidated.
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Affiliation(s)
- Toshiki Watanabe
- Department of Advanced Medical Innovation, St. Marianna University Graduate School of Medicine, Kanagawa, Japan; and Graduate School of Frontier Sciences, The University of Tokyo, Tokyo, Japan
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Schmitz NMR, Leibundgut K, Hirt A. Phosphorylation of the Retinoblastoma Protein in Childhood Acute Lymphoblastic Leukemia. Hematology 2016; 6:29-39. [DOI: 10.1080/10245332.2001.11746550] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Affiliation(s)
- Nicole M. R. Schmitz
- Department of Clinical Research, Tiefemustrasse 120, 3004 Bern, University of Bern, Switzerland
- Department of Pediatrics, Inselspital 3010 Bern, University of Bern, Switzerland
| | - Kurt Leibundgut
- Department of Pediatrics, Inselspital 3010 Bern, University of Bern, Switzerland
| | - Andreas Hirt
- Department of Clinical Research, Tiefemustrasse 120, 3004 Bern, University of Bern, Switzerland
- Department of Pediatrics, Inselspital 3010 Bern, University of Bern, Switzerland
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Tumor Suppressor Inactivation in the Pathogenesis of Adult T-Cell Leukemia. JOURNAL OF ONCOLOGY 2015; 2015:183590. [PMID: 26170835 PMCID: PMC4478360 DOI: 10.1155/2015/183590] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Accepted: 05/24/2015] [Indexed: 12/12/2022]
Abstract
Tumor suppressor functions are essential to control cellular proliferation, to activate the apoptosis or senescence pathway to eliminate unwanted cells, to link DNA damage signals to cell cycle arrest checkpoints, to activate appropriate DNA repair pathways, and to prevent the loss of adhesion to inhibit initiation of metastases. Therefore, tumor suppressor genes are indispensable to maintaining genetic and genomic integrity. Consequently, inactivation of tumor suppressors by somatic mutations or epigenetic mechanisms is frequently associated with tumor initiation and development. In contrast, reactivation of tumor suppressor functions can effectively reverse the transformed phenotype and lead to cell cycle arrest or death of cancerous cells and be used as a therapeutic strategy. Adult T-cell leukemia/lymphoma (ATLL) is an aggressive lymphoproliferative disease associated with infection of CD4 T cells by the Human T-cell Leukemia Virus Type 1 (HTLV-I). HTLV-I-associated T-cell transformation is the result of a multistep oncogenic process in which the virus initially induces chronic T-cell proliferation and alters cellular pathways resulting in the accumulation of genetic defects and the deregulated growth of virally infected cells. This review will focus on the current knowledge of the genetic and epigenetic mechanisms regulating the inactivation of tumor suppressors in the pathogenesis of HTLV-I.
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Dayaram T, Lemoine FJ, Donehower LA, Marriott SJ. Activation of WIP1 phosphatase by HTLV-1 Tax mitigates the cellular response to DNA damage. PLoS One 2013; 8:e55989. [PMID: 23405243 PMCID: PMC3566092 DOI: 10.1371/journal.pone.0055989] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 01/08/2013] [Indexed: 12/21/2022] Open
Abstract
Genomic instability stemming from dysregulation of cell cycle checkpoints and DNA damage response (DDR) is a common feature of many cancers. The cancer adult T cell leukemia (ATL) can occur in individuals infected with human T cell leukemia virus type 1 (HTLV-1), and ATL cells contain extensive chromosomal abnormalities, suggesting that they have defects in the recognition or repair of DNA damage. Since Tax is the transforming protein encoded by HTLV-1, we asked whether Tax can affect cell cycle checkpoints and the DDR. Using a combination of flow cytometry and DNA repair assays we showed that Tax-expressing cells exit G1 phase and initiate DNA replication prematurely following damage. Reduced phosphorylation of H2AX (γH2AX) and RPA2, phosphoproteins that are essential to properly initiate the DDR, was also observed in Tax-expressing cells. To determine the cause of decreased DDR protein phosphorylation in Tax-expressing cells, we examined the cellular phosphatase, WIP1, which is known to dephosphorylate γH2AX. We found that Tax can interact with Wip1 in vivo and in vitro, and that Tax-expressing cells display elevated levels of Wip1 mRNA. In vitro phosphatase assays showed that Tax can enhance Wip1 activity on a γH2AX peptide target by 2-fold. Thus, loss of γH2AX in vivo could be due, in part, to increased expression and activity of WIP1 in the presence of Tax. siRNA knockdown of WIP1 in Tax-expressing cells rescued γH2AX in response to damage, confirming the role of WIP1 in the DDR. These studies demonstrate that Tax can disengage the G1/S checkpoint by enhancing WIP1 activity, resulting in reduced DDR. Premature G1 exit of Tax-expressing cells in the presence of DNA lesions creates an environment that tolerates incorporation of random mutations into the host genome.
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Affiliation(s)
- Tajhal Dayaram
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Francene J. Lemoine
- Department of Biological Sciences, Northwestern State University of Louisiana, Natchitoches, Louisiana, United States of America
| | - Lawrence A. Donehower
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Susan J. Marriott
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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6
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Tan CSH, Linding R. Experimental and computational tools useful for (re)construction of dynamic kinaseâsubstrate networks. Proteomics 2009; 9:5233-42. [DOI: 10.1002/pmic.200900266] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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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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Leoncini L, Bellan C, De Falco G. Retinoblastoma gene family expression in lymphoid tissues. Oncogene 2006; 25:5309-14. [PMID: 16936752 DOI: 10.1038/sj.onc.1209619] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
It appears more and more clear that retinoblastoma (RB) family of proteins represents key molecules in tumour suppression. This family consists of pRb/p105, p107 and pRb2/p130, which participate in a gene regulatory network that governs the cellular response to antimitogenic signals, and whose deregulation constitutes one of the hallmarks of cancer. Irrespective of their structural and biochemical similarities, RB proteins carry out different functional tasks. The expression of RB gene family in the reactive lymphoid tissues again confirms the different role of each member in cell cycle control and differentiation of normal cells. These different functional properties appear to be maintained in tumours lymphoid tissues, where alterations of the RB/p105 gene appear to be relatively rare. In this review, we will summarize the current knowledge about the role of the RB proteins in reactive and neoplastic lymphoid tissue.
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Affiliation(s)
- L Leoncini
- Department of Human Pathology and Oncology, University of Siena, Siena, Italy.
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Mao X, Orchard G, Vonderheid EC, Nowell PC, Bagot M, Bensussan A, Russell-Jones R, Young BD, Whittaker SJ. Heterogeneous Abnormalities of CCND1 and RB1 in Primary Cutaneous T-Cell Lymphomas Suggesting Impaired Cell Cycle Control in Disease Pathogenesis. J Invest Dermatol 2006; 126:1388-95. [PMID: 16614728 DOI: 10.1038/sj.jid.5700224] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Upregulation of cyclin D1/B-cell leukemia/lymphoma 1 (CCND1/BCL1) is present in most mantle cell lymphomas with the t(11;14)(q13;q32) translocation. However, little is known about the abnormalities of CCND1 and its regulator RB1 in primary cutaneous T-cell lymphomas (CTCL). We analyzed CCND and RB status in CTCL using fluorescent in situ hybridization (FISH), immunohistochemistry (IHC), and Affymetrix expression microarray. FISH revealed loss of CCND1/BCL1 in five of nine Sézary syndrome (SS) cases but gain in two cases, and RB1 loss in four of seven SS cases. IHC showed absent CCND1/BCL1 expression in 18 of 30 SS, 10 of 23 mycosis fungoides (MF), and three of 10 primary cutaneous CD30+ anaplastic large-cell lymphoma (C-ALCL). Increased CCND1/BCL1 expression was seen in nine MF, seven C-ALCL, and six SS cases. Absent RB1 expression was detected in 8 of 12 MF and 7 of 9 SS cases, and raised RB1 expression in 7 of 8 C-ALCL. Affymetrix revealed increased gene expression of CCND2 in four of eight CTCL cases, CCND3 in three cases, and CDKN2C in two cases with a normal expression of CCND1 and RB1. These findings suggest heterogeneous abnormalities of CCND and RB in CTCL, in which dysregulated CCND and RB1 may lead to impaired cell cycle control.
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MESH Headings
- Cell Nucleus/chemistry
- Cell Nucleus/genetics
- Chromosome Aberrations
- Chromosome Deletion
- Chromosomes, Human, Pair 11/genetics
- Chromosomes, Human, Pair 14/genetics
- Cyclin D1/analysis
- Cyclin D1/genetics
- Female
- Gene Expression Regulation, Neoplastic
- Humans
- In Situ Hybridization, Fluorescence
- Lymphoma, Large-Cell, Anaplastic/chemistry
- Lymphoma, Large-Cell, Anaplastic/genetics
- Lymphoma, T-Cell, Cutaneous/chemistry
- Lymphoma, T-Cell, Cutaneous/genetics
- Male
- Mycosis Fungoides/chemistry
- Mycosis Fungoides/genetics
- Oligonucleotide Array Sequence Analysis
- Retinoblastoma Protein/analysis
- Retinoblastoma Protein/genetics
- Sezary Syndrome/chemistry
- Sezary Syndrome/genetics
- Skin Neoplasms/chemistry
- Skin Neoplasms/genetics
- Up-Regulation
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Affiliation(s)
- Xin Mao
- Skin Tumour Unit, St John's Institute of Dermatology, St Thomas' Hospital, King's College, London, UK.
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10
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Shimakage M, Inoue N, Ohshima K, Kawahara K, Oka T, Yasui K, Matsumoto K, Inoue H, Watari A, Higashiyama S, Yutsudo M. Down-regulation ofASY/Nogo transcription associated with progression of adult T-cell leukemia/lymphoma. Int J Cancer 2006; 119:1648-53. [PMID: 16646068 DOI: 10.1002/ijc.22011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [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 an aggressive form of human leukemia/lymphoma. Although this disease is initiated by infection with human T-lymphotropic virus type 1 (HTLV-1), many HTLV-1 carriers survive for a long period without aggressive illness, suggesting that other factors may play roles in the progression of ATLL to an aggressive state. However, the mechanism involved in this progression still remains unclear. Previously, we have reported that ASY/Nogo mRNA was markedly down-regulated in human small-cell lung carcinomas, whereas it was expressed in normal tissues and other lung carcinomas, such as adenocarcinoma and squamous cell carcinoma. To understand whether or not ASY/Nogo gene is involved in the progression of ATLL, we examined the expression of ASY/Nogo mRNA in smoldering, chronic and aggressive ATLL, and found that the expression level of ASY/Nogo mRNA was markedly reduced in clinically aggressive ATLL. HTLV-1 Tax expression was not affected by the down-regulation of ASY/Nogo mRNA. These results indicate that the ASY/Nogo gene may act as a suppressor against ATLL progression, independent of Tax expression.
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Affiliation(s)
- Misuzu Shimakage
- Clinical Research Institute, National Hospital Organization, Osaka National Hospital, Chuo-ku, Osaka, Japan.
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11
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Kehn K, Fuente CDL, Strouss K, Berro R, Jiang H, Brady J, Mahieux R, Pumfery A, Bottazzi ME, Kashanchi F. The HTLV-I Tax oncoprotein targets the retinoblastoma protein for proteasomal degradation. Oncogene 2005; 24:525-40. [PMID: 15580311 DOI: 10.1038/sj.onc.1208105] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Human T-cell leukemia virus type-I (HTLV-I), the etiologic agent of adult T-cell leukemia (ATL), is estimated to affect 10-20 million people worldwide. The transforming ability of HTLV-I has been largely attributed to the viral protein Tax, which modulates the activity of several well-known cell cycle regulators. An important cell cycle regulator, the retinoblastoma (Rb) protein, is often inactivated in many cancers including virally induced cancers. Upon examination of Rb status, we observed a decrease in Rb protein expression in HTLV-1-infected cell lines as well as in ex vivo ATL patient samples. Transient transfection assays indicated that decreased Rb protein levels were Tax dependent. Here, we demonstrate for the first time that Tax directly associates with Rb. This interaction was localized within the B pocket of Rb and the C-terminus of Tax (aa 245-353). Within the C-terminus of Tax, we have identified an LXCXE-like motif, that when mutated resulted in the loss of Tax/Rb interaction. Furthermore, through the use of proteasome inhibitors, such as MG-132, in vivo and proteasome degradation assays in vitro, we found that Tax destabilizes the hypo-phosphorylated (active) form of Rb via the proteasome pathway. Therefore, we propose a model whereby Tax targets Rb to the proteasome by acting as a molecular bridge bringing Rb into contact with the proteasome for degradation.
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Affiliation(s)
- Kylene Kehn
- Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, DC 20037, USA
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Azran I, Schavinsky-Khrapunsky Y, Aboud M. Role of Tax protein in human T-cell leukemia virus type-I leukemogenicity. Retrovirology 2004; 1:20. [PMID: 15310405 PMCID: PMC514576 DOI: 10.1186/1742-4690-1-20] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2004] [Accepted: 08/13/2004] [Indexed: 11/17/2022] Open
Abstract
HTLV-1 is the etiological agent of adult T-cell leukemia (ATL), the neurological syndrome TSP/HAM and certain other clinical disorders. The viral Tax protein is considered to play a central role in the process leading to ATL. Tax modulates the expression of many viral and cellular genes through the CREB/ATF-, SRF- and NF-κB-associated pathways. In addition, Tax employs the CBP/p300 and p/CAF co-activators for implementing the full transcriptional activation competence of each of these pathways. Tax also affects the function of various other regulatory proteins by direct protein-protein interaction. Through these activities Tax sets the infected T-cells into continuous uncontrolled replication and destabilizes their genome by interfering with the function of telomerase and topoisomerase-I and by inhibiting DNA repair. Furthermore, Tax prevents cell cycle arrest and apoptosis that would otherwise be induced by the unrepaired DNA damage and enables, thereby, accumulation of mutations that can contribute to the leukemogenic process. Together, these capacities render Tax highly oncogenic as reflected by its ability to transform rodent fibroblasts and primary human T-cells and to induce tumors in transgenic mice. In this article we discuss these effects of Tax and their apparent contribution to the HTLV-1 associated leukemogenic process. Notably, however, shortly after infection the virus enters into a latent state, in which viral gene expression is low in most of the HTLV-1 carriers' infected T-cells and so is the level of Tax protein, although rare infected cells may still display high viral RNA. This low Tax level is evidently insufficient for exerting its multiple oncogenic effects. Therefore, we propose that the latent virus must be activated, at least temporarily, in order to elevate Tax to its effective level and that during this transient activation state the infected cells may acquire some oncogenic mutations which can enable them to further progress towards ATL even if the activated virus is re-suppressed after a while. We conclude this review by outlining an hypothetical flow of events from the initial virus infection up to the ultimate ATL development and comment on the risk factors leading to ATL development in some people and to TSP/HAM in others.
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Affiliation(s)
- Inbal Azran
- Department of Microbiology and Immunology and Cancer Research Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Yana Schavinsky-Khrapunsky
- Department of Microbiology and Immunology and Cancer Research Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Mordechai Aboud
- Department of Microbiology and Immunology and Cancer Research Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
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Gatza ML, Watt JC, Marriott SJ. Cellular transformation by the HTLV-I Tax protein, a jack-of-all-trades. Oncogene 2003; 22:5141-9. [PMID: 12910251 DOI: 10.1038/sj.onc.1206549] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The human T-cell leukemia virus type I (HTLV-I) is an oncogenic retrovirus that is responsible for adult T-cell leukemia and a neurological disease, HTLV-I-associated myelopathy/tropical spastic paraparesis. HTLV-I encodes an oncogenic protein, Tax, which affects a variety of cellular functions prompting it to be referred to as a jack-of-all trades. The ability of Tax to both transcriptionally regulate cellular gene expression and to functionally inactivate proteins involved in cell-cycle progression and DNA repair provide the basis for Tax-mediated transformation and leukemogenesis. This review will concentrate on the effects of Tax on the dysregulation of the G(1)/S and G(2)/M checkpoints as well as the suppression of DNA damage repair leading to cellular transformation.
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Affiliation(s)
- Michael L Gatza
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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