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Old and New Facts and Speculations on the Role of the B Cell Receptor in the Origin of Chronic Lymphocytic Leukemia. Int J Mol Sci 2022; 23:ijms232214249. [PMID: 36430731 PMCID: PMC9693457 DOI: 10.3390/ijms232214249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/09/2022] [Accepted: 11/11/2022] [Indexed: 11/19/2022] Open
Abstract
The engagement of the B cell receptor (BcR) on the surface of leukemic cells represents a key event in chronic lymphocytic leukemia (CLL) since it can lead to the maintenance and expansion of the neoplastic clone. This notion was initially suggested by observations of the CLL BcR repertoire and of correlations existing between certain BcR features and the clinical outcomes of single patients. Based on these observations, tyrosine kinase inhibitors (TKIs), which block BcR signaling, have been introduced in therapy with the aim of inhibiting CLL cell clonal expansion and of controlling the disease. Indeed, the impressive results obtained with these compounds provided further proof of the role of BcR in CLL. In this article, the key steps that led to the determination of the role of BcR are reviewed, including the features of the CLL cell repertoire and the fine mechanisms causing BcR engagement and cell signaling. Furthermore, we discuss the biological effects of the engagement, which can lead to cell survival/proliferation or apoptosis depending on certain intrinsic cell characteristics and on signals that the micro-environment can deliver to the leukemic cells. In addition, consideration is given to alternative mechanisms promoting cell proliferation in the absence of BcR signaling, which can explain in part the incomplete effectiveness of TKI therapies. The role of the BcR in determining clonal evolution and disease progression is also described. Finally, we discuss possible models to explain the selection of a special BcR set during leukemogenesis. The BcR may deliver activation signals to the cells, which lead to their uncontrolled growth, with the possible collaboration of other still-undefined events which are capable of deregulating the normal physiological response of B cells to BcR-delivered stimuli.
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Zavacka K, Plevova K. Chromothripsis in Chronic Lymphocytic Leukemia: A Driving Force of Genome Instability. Front Oncol 2021; 11:771664. [PMID: 34900721 PMCID: PMC8661134 DOI: 10.3389/fonc.2021.771664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 11/01/2021] [Indexed: 11/22/2022] Open
Abstract
Chromothripsis represents a mechanism of massive chromosome shattering and reassembly leading to the formation of derivative chromosomes with abnormal functions and expression. It has been observed in many cancer types, importantly, including chronic lymphocytic leukemia (CLL). Due to the associated chromosomal rearrangements, it has a significant impact on the pathophysiology of the disease. Recent studies have suggested that chromothripsis may be more common than initially inferred, especially in CLL cases with adverse clinical outcome. Here, we review the main features of chromothripsis, the challenges of its assessment, and the potential benefit of its detection. We summarize recent findings of chromothripsis occurrence across hematological malignancies and address its causes and consequences in the context of CLL clinical features, as well as chromothripsis-related molecular abnormalities described in published CLL studies. Furthermore, we discuss the use of the current knowledge about genome functions associated with chromothripsis in the optimization of treatment strategies in CLL.
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Affiliation(s)
- Kristyna Zavacka
- Department of Internal Medicine - Hematology and Oncology, University Hospital Brno & Faculty of Medicine, Masaryk University, Brno, Czechia.,Center of Molecular Medicine, Central European Institute of Technology, Masaryk University, Brno, Czechia
| | - Karla Plevova
- Department of Internal Medicine - Hematology and Oncology, University Hospital Brno & Faculty of Medicine, Masaryk University, Brno, Czechia.,Center of Molecular Medicine, Central European Institute of Technology, Masaryk University, Brno, Czechia.,Institute of Medical Genetics and Genomics, University Hospital Brno & Masaryk University, Brno, Czechia
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3
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Jebaraj BMC, Stilgenbauer S. Telomere Dysfunction in Chronic Lymphocytic Leukemia. Front Oncol 2021; 10:612665. [PMID: 33520723 PMCID: PMC7844343 DOI: 10.3389/fonc.2020.612665] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/30/2020] [Indexed: 12/13/2022] Open
Abstract
Telomeres are nucleprotein structures that cap the chromosomal ends, conferring genomic stability. Alterations in telomere maintenance and function are associated with tumorigenesis. In chronic lymphocytic leukemia (CLL), telomere length is an independent prognostic factor and short telomeres are associated with adverse outcome. Though telomere length associations have been suggested to be only a passive reflection of the cell’s replication history, here, based on published findings, we suggest a more dynamic role of telomere dysfunction in shaping the disease course. Different members of the shelterin complex, which form the telomere structure have deregulated expression and POT1 is recurrently mutated in about 3.5% of CLL. In addition, cases with short telomeres have higher telomerase (TERT) expression and activity. TERT activation and shelterin deregulation thus may be pivotal in maintaining the minimal telomere length necessary to sustain survival and proliferation of CLL cells. On the other hand, activation of DNA damage response and repair signaling at dysfunctional telomeres coupled with checkpoint deregulation, leads to terminal fusions and genomic complexity. In summary, multiple components of the telomere system are affected and they play an important role in CLL pathogenesis, progression, and clonal evolution. However, processes leading to shelterin deregulation as well as cell intrinsic and microenvironmental factors underlying TERT activation are poorly understood. The present review comprehensively summarizes the complex interplay of telomere dysfunction in CLL and underline the mechanisms that are yet to be deciphered.
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Affiliation(s)
| | - Stephan Stilgenbauer
- Department of Internal Medicine III, University of Ulm, Ulm, Germany.,Klinik für Innere Medizin I, Universitätsklinikum des Saarlandes, Homburg, Germany
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4
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Cassar L, Nicholls C, Pinto AR, Chen R, Wang L, Li H, Liu JP. TGF-beta receptor mediated telomerase inhibition, telomere shortening and breast cancer cell senescence. Protein Cell 2016; 8:39-54. [PMID: 27696331 PMCID: PMC5233610 DOI: 10.1007/s13238-016-0322-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 08/03/2016] [Indexed: 01/09/2023] Open
Abstract
Human telomerase reverse transcriptase (hTERT) plays a central role in telomere lengthening for continuous cell proliferation, but it remains unclear how extracellular cues regulate telomerase lengthening of telomeres. Here we report that the cytokine bone morphogenetic protein-7 (BMP7) induces the hTERT gene repression in a BMPRII receptor- and Smad3-dependent manner in human breast cancer cells. Chonic exposure of human breast cancer cells to BMP7 results in short telomeres, cell senescence and apoptosis. Mutation of the BMPRII receptor, but not TGFbRII, ACTRIIA or ACTRIIB receptor, inhibits BMP7-induced repression of the hTERT gene promoter activity, leading to increased telomerase activity, lengthened telomeres and continued cell proliferation. Expression of hTERT prevents BMP7-induced breast cancer cell senescence and apoptosis. Thus, our data suggest that BMP7 induces breast cancer cell aging by a mechanism involving BMPRII receptor- and Smad3-mediated repression of the hTERT gene.
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Affiliation(s)
- Lucy Cassar
- Molecular Signaling Laboratory, Department of Immunology, Central Eastern Clinical School, Monash University, Prahran, VIC, 3181, Australia
| | - Craig Nicholls
- Molecular Signaling Laboratory, Department of Immunology, Central Eastern Clinical School, Monash University, Prahran, VIC, 3181, Australia
| | - Alex R Pinto
- Molecular Signaling Laboratory, Department of Immunology, Central Eastern Clinical School, Monash University, Prahran, VIC, 3181, Australia
| | - Ruping Chen
- Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, 311121, Zhejiang Province, China
| | - Lihui Wang
- Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, 311121, Zhejiang Province, China
| | - He Li
- Molecular Signaling Laboratory, Department of Immunology, Central Eastern Clinical School, Monash University, Prahran, VIC, 3181, Australia
| | - Jun-Ping Liu
- Molecular Signaling Laboratory, Department of Immunology, Central Eastern Clinical School, Monash University, Prahran, VIC, 3181, Australia. .,Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, 311121, Zhejiang Province, China.
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5
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Dal Bo M, D'Agaro T, Gobessi S, Zucchetto A, Dereani S, Rossi D, Zaja F, Pozzato G, Di Raimondo F, Gaidano G, Laurenti L, Del Poeta G, Efremov DG, Gattei V, Bomben R. The SIRT1/TP53 axis is activated upon B-cell receptor triggering via miR-132 up-regulation in chronic lymphocytic leukemia cells. Oncotarget 2016; 6:19102-17. [PMID: 26036258 PMCID: PMC4662478 DOI: 10.18632/oncotarget.3905] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 04/28/2015] [Indexed: 12/13/2022] Open
Abstract
The B-cell receptor (BCR) plays an important role in the pathogenesis and progression of chronic lymphocytic leukemia (CLL). By global microRNA profiling of CLL cells stimulated or not stimulated by anti-IgM, significant up-regulation of microRNAs from the miR-132~212 cluster was observed both in IGHV gene unmutated (UM) and mutated (M) CLL cells. Parallel gene expression profiling identified SIRT1, a deacetylase targeting several proteins including TP53, among the top-ranked miR-132 target genes down-regulated upon anti-IgM exposure. The direct regulation of SIRT1 expression by miR-132 was demonstrated using luciferase assays. The reduction of SIRT1 mRNA and protein (P = 0.001) upon anti-IgM stimulation was associated with an increase in TP53 acetylation (P = 0.007), and the parallel up-regulation of the TP53 target gene CDKN1A. Consistently, miR-132 transfections of CLL-like cells resulted in down-regulation of SIRT1 and an induction of a TP53-dependent apoptosis. Finally, in a series of 134 CLL samples, miR-132, when expressed above the median value, associated with prolonged time-to-first-treatment in patients with M CLL (HR = 0.41; P = 0.02). Collectively, the miR-132/SIRT1/TP53 axis was identified as a novel pathway triggered by BCR engagement that further increases the complexity of the interactions between tumor microenvironments and CLL cells.
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Affiliation(s)
- Michele Dal Bo
- Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano, Pordenone, Italy
| | - Tiziana D'Agaro
- Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano, Pordenone, Italy
| | - Stefania Gobessi
- Molecular Hematology, International Centre for Genetic Engineering and Biotechnology, Rome, Italy
| | - Antonella Zucchetto
- Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano, Pordenone, Italy
| | - Sara Dereani
- Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano, Pordenone, Italy
| | - Davide Rossi
- Division of Hematology, Department of Clinical and Experimental Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara, Italy
| | - Francesco Zaja
- Clinica Ematologica, Centro Trapianti e Terapie Cellulari "Carlo Melzi" DISM, Azienda Ospedaliera Universitaria S. Maria Misericordia, Udine, Italy
| | - Gabriele Pozzato
- Department of Internal Medicine and Hematology, Maggiore General Hospital, University of Trieste, Trieste, Italy
| | | | - Gianluca Gaidano
- Division of Hematology, Department of Clinical and Experimental Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara, Italy
| | - Luca Laurenti
- Department of Hematology, Catholic University Hospital A. Gemelli, Rome, Italy
| | - Giovanni Del Poeta
- Division of Hematology, S. Eugenio Hospital and University of Tor Vergata, Rome, Italy
| | - Dimitar G Efremov
- Molecular Hematology, International Centre for Genetic Engineering and Biotechnology, Rome, Italy
| | - Valter Gattei
- Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano, Pordenone, Italy
| | - Riccardo Bomben
- Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano, Pordenone, Italy
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6
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Mongini PKA, Gupta R, Boyle E, Nieto J, Lee H, Stein J, Bandovic J, Stankovic T, Barrientos J, Kolitz JE, Allen SL, Rai K, Chu CC, Chiorazzi N. TLR-9 and IL-15 Synergy Promotes the In Vitro Clonal Expansion of Chronic Lymphocytic Leukemia B Cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2015; 195:901-23. [PMID: 26136429 PMCID: PMC4505957 DOI: 10.4049/jimmunol.1403189] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/30/2015] [Indexed: 12/20/2022]
Abstract
Clinical progression of B cell chronic lymphocytic leukemia (B-CLL) reflects the clone's Ag receptor (BCR) and involves stroma-dependent B-CLL growth within lymphoid tissue. Uniformly elevated expression of TLR-9, occasional MYD88 mutations, and BCR specificity for DNA or Ags physically linked to DNA together suggest that TLR-9 signaling is important in driving B-CLL growth in patients. Nevertheless, reports of apoptosis after B-CLL exposure to CpG oligodeoxynucleotide (ODN) raised questions about a central role for TLR-9. Because normal memory B cells proliferate vigorously to ODN+IL-15, a cytokine found in stromal cells of bone marrow, lymph nodes, and spleen, we examined whether this was true for B-CLL cells. Through a CFSE-based assay for quantitatively monitoring in vitro clonal proliferation/survival, we show that IL-15 precludes TLR-9-induced apoptosis and permits significant B-CLL clonal expansion regardless of the clone's BCR mutation status. A robust response to ODN+IL-15 was positively linked to presence of chromosomal anomalies (trisomy-12 or ataxia telangiectasia mutated anomaly + del13q14) and negatively linked to a very high proportion of CD38(+) cells within the blood-derived B-CLL population. Furthermore, a clone's intrinsic potential for in vitro growth correlated directly with doubling time in blood, in the case of B-CLL with Ig H chain V region-unmutated BCR and <30% CD38(+) cells in blood. Finally, in vitro high-proliferator status was statistically linked to diminished patient survival. These findings, together with immunohistochemical evidence of apoptotic cells and IL-15-producing cells proximal to B-CLL pseudofollicles in patient spleens, suggest that collaborative ODN and IL-15 signaling may promote in vivo B-CLL growth.
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MESH Headings
- ADP-ribosyl Cyclase 1/metabolism
- Aged
- Aged, 80 and over
- Apoptosis/immunology
- Ataxia Telangiectasia Mutated Proteins/genetics
- B-Lymphocytes/immunology
- Cell Proliferation/genetics
- Cells, Cultured
- Chromosome Aberrations
- Female
- Humans
- Immunoglobulin Heavy Chains/genetics
- Interleukin-15/immunology
- Interleukin-15/pharmacology
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/immunology
- Leukemia, Lymphocytic, Chronic, B-Cell/mortality
- Male
- Membrane Glycoproteins/metabolism
- Middle Aged
- Myeloid Differentiation Factor 88/genetics
- Oligodeoxyribonucleotides/pharmacology
- Receptors, Antigen, B-Cell/immunology
- Signal Transduction/immunology
- Toll-Like Receptor 9/immunology
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Affiliation(s)
- Patricia K A Mongini
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030; Department of Molecular Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, NY 11549;
| | - Rashmi Gupta
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030
| | - Erin Boyle
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030
| | - Jennifer Nieto
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030
| | - Hyunjoo Lee
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030
| | - Joanna Stein
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030
| | - Jela Bandovic
- Department of Pathology, North Shore University Hospital-Long Island Jewish Medical Center, Manhasset, NY 11030
| | - Tatjana Stankovic
- School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Jacqueline Barrientos
- Department of Medicine, North Shore University Hospital-Long Island Jewish Medical Center, Manhasset, NY; and
| | - Jonathan E Kolitz
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030; Department of Medicine, North Shore University Hospital-Long Island Jewish Medical Center, Manhasset, NY; and Department of Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, NY
| | - Steven L Allen
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030; Department of Medicine, North Shore University Hospital-Long Island Jewish Medical Center, Manhasset, NY; and Department of Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, NY
| | - Kanti Rai
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030; Department of Medicine, North Shore University Hospital-Long Island Jewish Medical Center, Manhasset, NY; and Department of Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, NY
| | - Charles C Chu
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030; Department of Molecular Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, NY 11549
| | - Nicholas Chiorazzi
- The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030; Department of Molecular Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, NY 11549; Department of Medicine, North Shore University Hospital-Long Island Jewish Medical Center, Manhasset, NY; and Department of Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, NY
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7
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Gopal PK, Paul M, Paul S. Curcumin Induces Caspase Mediated Apoptosis in JURKAT Cells by Disrupting the Redox Balance. Asian Pac J Cancer Prev 2014; 15:93-100. [DOI: 10.7314/apjcp.2014.15.1.93] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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8
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IL-21 and CD40L signals from autologous T cells can induce antigen-independent proliferation of CLL cells. Blood 2013; 122:3010-9. [PMID: 24014238 DOI: 10.1182/blood-2012-11-467670] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Chronic lymphocytic leukemia (CLL) cells multiply in secondary lymphoid tissue, but the mechanisms leading to their proliferation are still uncertain. In addition to B-cell receptor (BCR)-triggered signals, other microenvironmental factors might well be involved. In proliferation centers, leukemic B cells are in close contact with CD4(+)CD40L(+) T cells. Therefore, we here dissected the signals provided by autologous activated T cells (Tact) to CLL cells. Although the gene expression profile induced by Tact was highly similar to that induced by sole CD40 signaling, an obvious difference was that Tact induced proliferation of CLL cells. We determined that stimulation with only CD40L+IL-21 was sufficient to induce robust proliferation in CLL cells. We then defined an interleukin (IL)-21-induced gene signature in CLL, containing components of Janus kinase/signal transducer and activator of transcription and apoptosis pathways, and this signature could be detected in lymph node (LN) samples from patients. Finally, we could detect IL-21 RNA and protein in LN, and IL-21 production ex vivo by LN CD4(+)CXCR5(+) follicular helper T cells. These results indicate that in addition to BCR signaling, activated T cells might contribute to CLL cell proliferation via CD40 and IL-21. Targeting these signaling pathways might offer new venues for treatment of CLL.
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Yamada O, Kawauchi K. The role of the JAK-STAT pathway and related signal cascades in telomerase activation during the development of hematologic malignancies. JAKSTAT 2013; 2:e25256. [PMID: 24416646 PMCID: PMC3876434 DOI: 10.4161/jkst.25256] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 05/25/2013] [Accepted: 06/03/2013] [Indexed: 12/28/2022] Open
Abstract
Telomerase, comprising a reverse transcriptase protein (TERT) and an RNA template, plays a critical role during senescence and carcinogenesis; however, the mechanisms by which telomerase is regulated remain to be elucidated. Several signaling pathways are involved in the activation of TERT at multistep levels. The JAK-STAT pathway is indispensable for mediating signals through growth factor and cytokine receptors during the development of hematopoietic cells, and its activity is frequently upregulated in hematological malignancies. Here, we review the role of the JAK-STAT pathway and related signaling cascades in the regulation of telomerase in hematological malignancies.
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Affiliation(s)
- Osamu Yamada
- Medical Research Institute and Department of Hematology; Tokyo Women's Medical University; Tokyo, Japan
| | - Kiyotaka Kawauchi
- Department of Medicine; Tokyo Women's Medical University; Medical Center East; Tokyo, Japan ; Nishiogu Clinic; Tokyo, Japan
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10
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Palma M, Parker A, Hojjat-Farsangi M, Forster J, Kokhaei P, Hansson L, Osterborg A, Mellstedt H. Telomere length and expression of human telomerase reverse transcriptase splice variants in chronic lymphocytic leukemia. Exp Hematol 2013; 41:615-26. [PMID: 23548418 DOI: 10.1016/j.exphem.2013.03.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 03/14/2013] [Accepted: 03/21/2013] [Indexed: 01/15/2023]
Abstract
Telomerase activity and telomere length (TL) are prognostic markers in chronic lymphocytic leukemia (CLL). The rate-limiting component of telomerase is human telomerase reverse transcriptase (hTERT), for which multiple transcripts exist. Two splicing sites, α and β, have been described that generate deleted transcripts. Only the full-length (FL; α⁺β⁺) transcript translates into a functional protein. The aim of this work was to characterize hTERT splice variants in CLL in relation to disease activity, clinical stage, immunoglobulin heavy chain variable (IGHV) genes mutational status, and TL. Real-time polymerase chain reaction assays were validated for quantification of the hTERT transcripts with either α deletion (del-α; α⁻β⁺)), β deletion (del-β; α⁺β⁻) or both α and β deletions (del-αβ; α⁻β⁻). The splice variant expression pattern was studied in 97 patients with CLL, 6 healthy control subjects, and one CD34 cell sample. TL was assessed with real-time polymerase chain reaction in 71 of 97 samples. Thirty-two percent of the cases did not express any of the splice variants. Average FL expression was 5.5-fold higher in IGHV-unmutated (n = 35) compared with mutated (n = 59) patients (p < 0.0001). FL levels correlated directly with the percentage of IGHV homology (r = 0.34; p = 0.0007) and inversely with TL (r = -0.44; p = 0.0001). Overall, FL expression correlated significantly with that of the other splice variants. All transcripts were more frequently expressed in progressive compared with nonprogressive patients (p < 0.0001 for FL and del-α; p = 0.01 for del-β; and p = 0.006 for del-αβ). This study provides a detailed insight into the hTERT transcript pattern in CLL, highlighting the necessity of subgrouping patients according to IGHV mutation status when analyzing hTERT expression.
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Affiliation(s)
- Marzia Palma
- Immune and Gene Therapy Laboratory, Department of Oncology and Pathology, Cancer Centre Karolinska, Karolinska Institutet, Stockholm, Sweden.
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11
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Cesano A, Perbellini O, Evensen E, Chu CC, Cioffi F, Ptacek J, Damle RN, Chignola R, Cordeiro J, Yan XJ, Hawtin RE, Nichele I, Ware JR, Cavallini C, Lovato O, Zanotti R, Rai KR, Chiorazzi N, Pizzolo G, Scupoli MT. Association between B-cell receptor responsiveness and disease progression in B-cell chronic lymphocytic leukemia: results from single cell network profiling studies. Haematologica 2012; 98:626-34. [PMID: 23144194 DOI: 10.3324/haematol.2012.071910] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
While many prognostic markers in B-cell chronic lymphocytic leukemia provide insight into the biology of the disease, few have been demonstrated to be useful in the daily management of patients. B-cell receptor signaling is a driving event in the progression of B-cell chronic lymphocytic leukemia and markers of B-cell receptor responsiveness have been shown to be of prognostic value. Single cell network profiling, a multiparametric flow cytometry-based assay, allows functional signaling analysis at the level of the single cell. B-cell receptor signaling proteins (i.e. p-SYK, p-NF-κB p65, p-ERK, p-p38, p-JNK) were functionally characterized by single cell network profiling in samples from patients with B-cell chronic lymphocytic leukemia in an exploratory study (n=27) after stimulation with anti-IgM. Significant associations of single cell network profiling data with clinical outcome (i.e. time to first treatment), as assessed by Cox regression models, were then confirmed in patients' samples in two other sequential independent studies, i.e. test study 1 (n=30), and test study 2 (n=37). In the exploratory study, higher responsiveness of the B-cell receptor signaling proteins to anti-IgM was associated with poor clinical outcomes. Patients' clustering based on signaling response was at least as powerful in discriminating different disease courses as traditional prognostic markers. In an unselected subgroup of patients with Binet stage A disease (n=21), increased anti-IgM-modulated p-ERK signaling was shown to be a significant, independent predictor of shorter time to first treatment. This result was independently confirmed in two test cohorts from distinct populations of patients. In conclusion, these findings support the utility of the single cell network profiling assay in elucidating signaling perturbations with the potential for the development of a clinically useful prognostic test in patients with early stage B-cell chronic lymphocytic leukemia. These data support the clinical relevance of B-cell receptor signaling in B-cell chronic lymphocytic leukemia, and suggest a key role of ERK activation in the physiopathology of this leukemia.
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12
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Novel Agents and Emerging Strategies for Targeting the B-Cell Receptor Pathway in CLL. Mediterr J Hematol Infect Dis 2012; 4:e2012067. [PMID: 23170196 PMCID: PMC3499997 DOI: 10.4084/mjhid.2012.067] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 09/28/2012] [Indexed: 02/06/2023] Open
Abstract
Chronic lymphocytic leukemia (CLL) is a disease of malignant CD5+ B lymphocytes that are characterized by frequent expression of autoreactive B-cell receptors (BCRs) and marked dependence on microenvironmental signals for proliferation and survival. Among the latter, signals propagated through the BCR are believed to play a key role in leukemia initiation, maintenance and evolution. Drugs that can disrupt these signals have recently emerged as potential therapeutic agents in CLL and several of them are currently being evaluated in clinical trials. Particularly promising clinical responses have been obtained with inhibitors of the kinases SYK, BTK, and PI3Kδ, which function by blocking BCR signal transduction. In addition, recent studies focusing on the phosphatase PTPN22, which is involved in the pathogenesis of multiple autoimmune diseases and is markedly overexpressed in CLL cells, suggest that it may be possible in the future to develop strategies that will selectively reprogram BCR survival signals into signals that induce leukemic cell death. This review focuses on the biological basis behind these strategies and highlights some of the most promising BCR-targeting agents in ongoing preclinical and clinical studies.
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