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Chung EY, Psathas JN, Yu D, Li Y, Weiss MJ, Thomas-Tikhonenko A. CD19 is a major B cell receptor-independent activator of MYC-driven B-lymphomagenesis. J Clin Invest 2012; 122:2257-66. [PMID: 22546857 DOI: 10.1172/jci45851] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 03/27/2012] [Indexed: 12/13/2022] Open
Abstract
PAX5, a B cell-specific transcription factor, is overexpressed through chromosomal translocations in a subset of B cell lymphomas. Previously, we had shown that activation of immunoreceptor tyrosine-based activation motif (ITAM) proteins and B cell receptor (BCR) signaling by PAX5 contributes to B-lymphomagenesis. However, the effect of PAX5 on other oncogenic transcription factor-controlled pathways is unknown. Using a MYC-induced murine lymphoma model as well as MYC-transformed human B cell lines, we found that PAX5 controls c-MYC protein stability and steady-state levels. This promoter-independent, posttranslational mechanism of c-MYC regulation was independent of ITAM/BCR activity. Instead it was controlled by another PAX5 target, CD19, through the PI3K-AKT-GSK3β axis. Consequently, MYC levels in B cells from CD19-deficient mice were sharply reduced. Conversely, reexpression of CD19 in murine lymphomas with spontaneous silencing of PAX5 boosted MYC levels, expression of its key target genes, cell proliferation in vitro, and overall tumor growth in vivo. In human B-lymphomas, CD19 mRNA levels were found to correlate with those of MYC-activated genes. They also negatively correlated with the overall survival of patients with lymphoma in the same way that MYC levels do. Thus, CD19 is a major BCR-independent regulator of MYC-driven neoplastic growth in B cell neoplasms.
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Affiliation(s)
- Elaine Y Chung
- Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, The Children’s Hospital of Philadelphia, Philadelphia 19104-4399, Pennsylvania, USA
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Cozma D, Yu D, Hodawadekar S, Azvolinsky A, Grande S, Tobias JW, Metzgar MH, Paterson J, Erikson J, Marafioti T, Monroe JG, Atchison ML, Thomas-Tikhonenko A. B cell activator PAX5 promotes lymphomagenesis through stimulation of B cell receptor signaling. J Clin Invest 2007; 117:2602-10. [PMID: 17717600 PMCID: PMC1950455 DOI: 10.1172/jci30842] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 05/29/2007] [Indexed: 01/16/2023] Open
Abstract
The presumed involvement of paired box gene 5 (PAX5) in B-lymphomagenesis is based largely on the discovery of Pax5-specific translocations and somatic hypermutations in non-Hodgkin lymphomas. Yet mechanistically, the contribution of Pax5 to neoplastic growth remains undeciphered. Here we used 2 Myc-induced mouse B lymphoma cell lines, Myc5-M5 and Myc5-M12, which spontaneously silence Pax5. Reconstitution of these cells with Pax5-tamoxifen receptor fusion protein (Pax5ER(TAM)) increased neoplastic growth in a hormone-dependent manner. Conversely, expression of dominant-negative Pax5 in murine lymphomas and Pax5 knockdown in human lymphomas negatively affected cell expansion. Expression profiling revealed that Pax5 was required to maintain mRNA levels of several crucial components of B cell receptor (BCR) signaling, including CD79a, a protein with the immunoreceptor tyrosine-based activation motif (ITAM). In contrast, expression of 2 known ITAM antagonists, CD22 and PIR-B, was suppressed. The key role of BCR/ITAM signaling in Pax5-dependent lymphomagenesis was corroborated in Syk, an ITAM-associated tyrosine kinase. Moreover, we observed consistent expression of phosphorylated BLNK, an activated BCR adaptor protein, in human B cell lymphomas. Thus, stimulation of neoplastic growth by Pax5 occurs through BCR and is sensitive to genetic and pharmacological inhibitors of this pathway.
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Affiliation(s)
- Diana Cozma
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Duonan Yu
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Suchita Hodawadekar
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Anna Azvolinsky
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Shannon Grande
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - John W. Tobias
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Michele H. Metzgar
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Jennifer Paterson
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Jan Erikson
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Teresa Marafioti
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - John G. Monroe
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Michael L. Atchison
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Andrei Thomas-Tikhonenko
- Department of Pathobiology and
Department of Animal Biology, School of Veterinary Medicine,
Department of Pathology and Laboratory Medicine, School of Medicine, and
Biomedical Informatics Core, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Oxford, United Kingdom
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Hodawadekar S, Yu D, Cozma D, Freedman B, Sunyer O, Atchison ML, Thomas-Tikhonenko A. B-Lymphoma cells with epigenetic silencing of Pax5 trans-differentiate into macrophages, but not other hematopoietic lineages. Exp Cell Res 2006; 313:331-40. [PMID: 17098231 PMCID: PMC1839943 DOI: 10.1016/j.yexcr.2006.10.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 10/07/2006] [Accepted: 10/16/2006] [Indexed: 01/08/2023]
Abstract
In mice, zygotic or pro-B-cell-specific knock-out of the Pax5 gene allows differentiation of pro-B-cells into all hematopoietic lineages. We previously generated and characterized a murine B-cell lymphoma, dubbed Myc5, whose cells spontaneously lose Pax5 expression when cultured in vitro, but regain it when re-injected into syngeneic mice. In cultured Myc5 cells, the loss of Pax5 correlates with the acquisition of myeloid markers, such as CD11b and F4/80. Here, we sought to determine whether these cells are truly B-macrophage-restricted or, like Pax5-null progenitors, can give rise to additional hematopoietic lineages. In vitro differentiation assays with various cytokines showed that Myc5 cells do not differentiate into NK cells, dendritic cells, neutrophils, or osteoclasts. At the same time, in the presence of macrophage colony-stimulating factor (M-CSF), they readily phagocytose latex beads and provide T-cell help. Both phenomena are indicative of the bona fide macrophage phenotype. Conversely, enforced Pax5 re-expression in macrophage-like Myc5 cells led to down-regulation of the M-CSF receptor and re-acquisition of some B-cell surface markers (e.g., CD79a) and lineage-specific transcription factors (e.g., IRF4 and Blimp). Retrovirally encoded Pax5 also restored expression of several master B-cell differentiation proteins, such as the IL-7 receptor and transcription factor E2A. In contrast, levels of EBF were unaffected by Pax5 suggesting that EBF acts exclusively upstream of Pax5 and might contribute to Pax5 expression. Indeed, transduction with an EBF-encoding retrovirus partly reactivated endogenous Pax5. Our data reveal the complex relationship between B-cell-specific transcription factors and suggest the existence of numerous feedback mechanisms.
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Affiliation(s)
- Suchita Hodawadekar
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104-6051
| | - Duonan Yu
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104-6051
| | - Diana Cozma
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104-6051
| | - Bruce Freedman
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104-6051
| | - Oriol Sunyer
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104-6051
| | - Michael L. Atchison
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104-6051
| | - Andrei Thomas-Tikhonenko
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104-6051
- * Corresponding Author: , Tel: (215) 573-5138, Fax: (215) 746-0380
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