51
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Archangelo LF, Greif PA, Hölzel M, Harasim T, Kremmer E, Przemeck GKH, Eick D, Deshpande AJ, Buske C, de Angelis MH, Saad STO, Bohlander SK. The CALM and CALM/AF10 interactor CATS is a marker for proliferation. Mol Oncol 2008; 2:356-67. [PMID: 19383357 DOI: 10.1016/j.molonc.2008.08.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 08/26/2008] [Accepted: 08/27/2008] [Indexed: 01/05/2023] Open
Abstract
The CATS protein was recently identified as a novel CALM interacting protein. CATS increases the nuclear and specifically the nucleolar localization of the leukemogenic CALM/AF10 fusion protein. We cloned and characterized the murine Cats gene. Detailed analysis of murine Cats expression during mouse embryogenesis showed an association with rapidly proliferating tissues. Interestingly, the Cats transcript is highly expressed in murine hematopoietic cells transformed by CALM/AF10. The CATS protein is highly expressed in leukemia, lymphoma and tumor cell lines but not in non-proliferating T-cells or human peripheral blood lymphocytes. CATS protein levels are cell cycle dependent and it is induced by mitogens, suggesting a role of CATS in the control of cell proliferation and possibly CALM/AF10-mediated leukemogenesis.
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Affiliation(s)
- Leticia Fröhlich Archangelo
- Department of Medicine III, University of Munich Hospital Grosshadern, German Research Center for Environmental Health, Munich, Germany
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52
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Yokoyama A, Cleary ML. Menin critically links MLL proteins with LEDGF on cancer-associated target genes. Cancer Cell 2008; 14:36-46. [PMID: 18598942 PMCID: PMC2692591 DOI: 10.1016/j.ccr.2008.05.003] [Citation(s) in RCA: 399] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 05/15/2008] [Accepted: 05/15/2008] [Indexed: 12/15/2022]
Abstract
Menin displays the unique ability to either promote oncogenic function in the hematopoietic lineage or suppress tumorigenesis in the endocrine lineage; however, its molecular mechanism of action has not been defined. We demonstrate here that these discordant functions are unified by menin's ability to serve as a molecular adaptor that physically links the MLL (mixed-lineage leukemia) histone methyltransferase with LEDGF (lens epithelium-derived growth factor), a chromatin-associated protein previously implicated in leukemia, autoimmunity, and HIV-1 pathogenesis. LEDGF is required for both MLL-dependent transcription and leukemic transformation. Conversely, a subset of menin mutations in multiple endocrine neoplasia type 1 patients abrogate interaction with LEDGF while preserving MLL interaction but nevertheless compromise MLL/menin-dependent functions. Thus, LEDGF critically associates with MLL and menin at the nexus of transcriptional pathways that are recurrently targeted in diverse diseases.
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MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- Chromatin/metabolism
- Chromatin Assembly and Disassembly
- Gene Expression Regulation, Leukemic
- HeLa Cells
- Histone Methyltransferases
- Histone-Lysine N-Methyltransferase/metabolism
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Humans
- Leukemia/enzymology
- Leukemia/genetics
- Leukemia/metabolism
- Leukemia/pathology
- Mice
- Mice, Inbred C57BL
- Multiple Endocrine Neoplasia Type 1/genetics
- Multiple Endocrine Neoplasia Type 1/metabolism
- Mutation
- Myeloid Progenitor Cells/enzymology
- Myeloid Progenitor Cells/metabolism
- Myeloid-Lymphoid Leukemia Protein/genetics
- Myeloid-Lymphoid Leukemia Protein/metabolism
- Protein Binding
- Protein Methyltransferases
- Protein Structure, Tertiary
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- RNA Interference
- Time Factors
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription, Genetic
- Transduction, Genetic
- Tumor Suppressor Proteins/genetics
- Tumor Suppressor Proteins/metabolism
- U937 Cells
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Affiliation(s)
- Akihiko Yokoyama
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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53
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Wei J, Wunderlich M, Fox C, Alvarez S, Cigudosa JC, Wilhelm JS, Zheng Y, Cancelas JA, Gu Y, Jansen M, DiMartino JF, Mulloy JC. Microenvironment determines lineage fate in a human model of MLL-AF9 leukemia. Cancer Cell 2008; 13:483-95. [PMID: 18538732 PMCID: PMC2486365 DOI: 10.1016/j.ccr.2008.04.020] [Citation(s) in RCA: 245] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 12/26/2007] [Accepted: 04/22/2008] [Indexed: 12/12/2022]
Abstract
Faithful modeling of mixed-lineage leukemia in murine cells has been difficult to achieve. We show that expression of MLL-AF9 in human CD34+ cells induces acute myeloid, lymphoid, or mixed-lineage leukemia in immunodeficient mice. Some leukemia stem cells (LSC) were multipotent and could be lineage directed by altering either the growth factors or the recipient strain of mouse, highlighting the importance of microenvironmental cues. Other LSC were strictly lineage committed, demonstrating the heterogeneity of the stem cell compartment in MLL disease. Targeting the Rac signaling pathway by pharmacologic or genetic means resulted in rapid and specific apoptosis of MLL-AF9 cells, suggesting that the Rac signaling pathway may be a valid therapeutic target in MLL-rearranged AML.
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MESH Headings
- Aneuploidy
- Animals
- Antigens, CD34/analysis
- Apoptosis
- Cell Culture Techniques
- Cell Line, Transformed
- Cell Lineage
- Cell Proliferation
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- Chromosomes, Human, Pair 11
- Environment
- Fetal Blood/immunology
- Fetal Blood/metabolism
- Fetal Stem Cells/immunology
- Fetal Stem Cells/metabolism
- Fetal Stem Cells/pathology
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic
- Genotype
- Humans
- Intercellular Signaling Peptides and Proteins/metabolism
- Leukemia, Experimental/metabolism
- Leukemia, Experimental/pathology
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/pathology
- Mice
- Mice, Inbred NOD
- Mice, SCID
- Multipotent Stem Cells/immunology
- Multipotent Stem Cells/metabolism
- Multipotent Stem Cells/pathology
- Myeloid-Lymphoid Leukemia Protein/genetics
- Myeloid-Lymphoid Leukemia Protein/metabolism
- Neoplastic Stem Cells/immunology
- Neoplastic Stem Cells/metabolism
- Neoplastic Stem Cells/pathology
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Phenotype
- Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics
- Precursor Cell Lymphoblastic Leukemia-Lymphoma/metabolism
- Precursor Cell Lymphoblastic Leukemia-Lymphoma/pathology
- Signal Transduction
- Species Specificity
- Stem Cell Transplantation
- Time Factors
- Transduction, Genetic
- Translocation, Genetic
- rac GTP-Binding Proteins/genetics
- rac GTP-Binding Proteins/metabolism
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Affiliation(s)
- Junping Wei
- Division of Experimental Hematology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
| | - Mark Wunderlich
- Division of Experimental Hematology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
| | - Catherine Fox
- Division of Experimental Hematology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
| | - Sara Alvarez
- Molecular Cytogenetics Group, Centro Nacional de Investigaciones Oncologicas, Madrid Spain
| | - Juan C. Cigudosa
- Molecular Cytogenetics Group, Centro Nacional de Investigaciones Oncologicas, Madrid Spain
| | - Jamie S. Wilhelm
- Division of Experimental Hematology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
| | - Yi Zheng
- Division of Experimental Hematology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
| | - Jose A. Cancelas
- Division of Experimental Hematology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
- Hoxworth Blood Center, University of Cincinnati,, Cincinnati OH
| | - Yi Gu
- Division of Experimental Hematology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
| | - Michael Jansen
- Division of Experimental Hematology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
| | - Jorge F. DiMartino
- Division of Hematology Oncology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
| | - James C. Mulloy
- Division of Experimental Hematology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati OH
- Corresponding author: James C. Mulloy, CCHMC, 3333 Burnet Avenue, ML 7013, Cincinnati OH 45226 phone (513)-636-1844, fax (513)-404-3768,
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54
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McCormack E, Bruserud O, Gjertsen BT. Review: genetic models of acute myeloid leukaemia. Oncogene 2008; 27:3765-79. [PMID: 18264136 DOI: 10.1038/onc.2008.16] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The use of genetically engineered mice (GEM) have been critical in understanding disease states such as cancer, and none more so than acute myelogenous leukaemia (AML), a disease characterized by over 100 distinct chromosomal translocations. A substantial proportion of cases exhibiting recurrent reciprocal translocations at diagnosis, such as t(8;21) or t(15;17) have been exhaustively studied and are currently employed in clinical diagnosis. However, a definitive conclusion regarding the leukaemogenic potential of defined transgenes for this disease remains elusive. While it is increasingly apparent that a number of cooperating mutations are necessary to develop a leukaemic phenotype, the number of models reflecting these synergisms remains few. Furthermore, little emphasis has been paid to the effect of chromosomal translocations other than recurrent genetic abnormalities, with no models reflecting the multiple abnormalities observed in high-risk cases of AML accounting for 8-10% of adult AML. Here we review the differing technologies employed in generation of GEM of AML. We discuss the relevance of GEM AML from embryonic stem cell-mediated (for example retinoic acid receptor-alpha fusions and AML1/ETO) models; through to the valuable retroviral-mediated gene transfer models. The latter have been used to great effect in defining the transforming properties of chromosomal translocation products such as MLL (found in 5-6% of all AML cases) and NUP98 (denoting poor prognosis in therapy-related disease) and particularly when co-transduced with bad prognostic factors such as Flt3 mutations. Finally, we comment on the emergence of newer transduction technologies, which can regulate the level of expression to defined cell lineages in both primary murine and human xenografts, and discuss how combining multiple genetic modalities, more relevant models of this complex disease are being generated.
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Affiliation(s)
- E McCormack
- Institute of Medicine, Haematology Section, University of Bergen, Bergen, Norway
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55
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Forissier S, Razanajaona D, Ay AS, Martel S, Bartholin L, Rimokh R. AF10-dependent transcription is enhanced by its interaction with FLRG. Biol Cell 2008; 99:563-71. [PMID: 17868029 DOI: 10.1042/bc20060131] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND INFORMATION FLRG (follistatin-related gene) is a secreted glycoprotein which is very similar to follistatin. As observed for follistatin, FLRG is involved in the regulation of various biological processes through its binding to members of the TGFbeta (transforming growth factor beta) superfamily, activin, BMPs (bone morphogenetic proteins) and myostatin. Unlike follistatin, FLRG has been found to be both secreted and localized within the nucleus of many FLRG-producing cells, suggesting the existence of specific intracellular functions of the protein. RESULTS In order to analyse the function of the nuclear form of FLRG, we performed a yeast two-hybrid screen, in which we identified AF10 [ALL1 (acute lymphoblastic leukaemia) fused gene from chromosome 10], a translocation partner of the MLL (mixed-lineage leukaemia) oncogene in human leukaemia, as a FLRG-interacting protein. This interaction was confirmed by far-Western-blot analysis and co-immunoprecipitation with transfected COS-7 cells. The N-terminal region of AF10, including the PHD (plant homeodomain), is sufficient to mediate this interaction, and has been shown to be involved in AF10 homo-oligomerization. By immunoprecipitation experiments, we showed that FLRG enhances the homo-oligomerization of AF10. Functional studies demonstrated that FLRG enhances the transactivation properties of the AF10 protein fused to Gal4 DNA-binding domains in transient transfection assays. CONCLUSIONS Our present study provides novel insights into the function of the nuclear form of the FLRG protein, which is revealed as a novel regulator of transcription. The nuclear isoform of FLRG lacks an intrinsic transactivation domain, but enhances AF10-mediated transcription, probably through promoting the homo-oligomerization of AF10, thus facilitating the recruitment of co-activators.
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56
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Abstract
Chromosomal translocations are important genetic perturbations frequently associated with hematologic malignancies; characterization of these events has been a rich source of insights into the mechanisms that lead to malignant transformation. The t(10;11)(p13;q14-21) results in a recently identified rare but recurring chromosomal translocation seen in patients with ALL as well as AML, and results in the production of a CALM-AF10 fusion gene. Although the details by which the CALM-AF10 fusion protein exerts its leukemogenic effect remain unclear, emerging data suggests that the CALM-AF10 fusion impairs differentiation of hematopoietic cells, at least in part via an upregulation of HOXA cluster genes. This review discusses the normal structure and function of CALM and AF10, describes the spectrum of clinical findings seen in patients with CALM-AF10 fusions, summarizes recently published CALM-AF10 mouse models and highlights the role of HOXA cluster gene activation in CALM-AF10 leukemia.
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Affiliation(s)
- D Caudell
- Genetics Branch, National Cancer Institute, National Institutes for Health, Bethesda, MD 20889-5105, USA
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57
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The leukemogenic CALM/AF10 fusion protein alters the subcellular localization of the lymphoid regulator Ikaros. Oncogene 2007; 27:2886-96. [PMID: 18037964 DOI: 10.1038/sj.onc.1210945] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The t(10;11)(p13;q14) translocation leads to the fusion of the CALM and AF10 genes. This translocation can be found as the sole cytogenetic abnormality in acute lymphoblastic leukemia, acute myeloid leukemia and in malignant lymphomas. The expression of CALM/AF10 in primary murine bone marrow cells results in the development of an aggressive leukemia in a murine bone marrow transplantation model. Using a yeast two-hybrid screen, we identified the lymphoid regulator Ikaros as an AF10 interacting protein. Interestingly, Ikaros is required for normal development of lymphocytes, and aberrant expression of Ikaros has been found in leukemia. In a murine model, the expression of a dominant negative isoform of Ikaros causes leukemias and lymphomas. The Ikaros interaction domain of AF10 was mapped to the leucine zipper domain of AF10, which is required for malignant transformation both by the CALM/AF10 and the MLL/AF10 fusion proteins. The interaction between AF10 and Ikaros was confirmed by GST pull down and co-immunoprecipitation. Coexpression of CALM/AF10 but not of AF10 alters the subcellular localization of Ikaros in murine fibroblasts. The transcriptional repressor activity of Ikaros is reduced by AF10. These results suggest that CALM/AF10 might interfere with normal Ikaros function, and thereby block lymphoid differentiation in CALM/AF10 positive leukemias.
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58
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Caudell D, Zhang Z, Chung YJ, Aplan PD. Expression of a CALM-AF10 fusion gene leads to Hoxa cluster overexpression and acute leukemia in transgenic mice. Cancer Res 2007; 67:8022-31. [PMID: 17804713 PMCID: PMC1986634 DOI: 10.1158/0008-5472.can-06-3749] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To assess the role of the CALM-AF10 fusion gene in leukemic transformation in vivo, we generated transgenic mice that expressed a CALM-AF10 fusion gene. Depending on the transgenic line, at least 40% to 50% of the F(1) generation mice developed acute leukemia at a median age of 12 months. Leukemic mice typically had enlarged spleens, invasion of parenchymal organs with malignant cells, and tumors with myeloid markers such as myeloperoxidase, Mac1, and Gr1. Although most leukemias were acute myeloid leukemia, many showed lymphoid features, such as CD3 staining, or clonal Tcrb or Igh gene rearrangements. Mice were clinically healthy for the first 9 months of life and had normal peripheral blood hemograms but showed impaired thymocyte differentiation, manifested by decreased CD4(+)/CD8(+) cells and increased immature CD4(-)/CD8(-) cells in the thymus. Hematopoietic tissues from both clinically healthy and leukemic CALM-AF10 mice showed up-regulation of Hoxa cluster genes, suggesting a potential mechanism for the impaired differentiation. The long latency period and incomplete penetrance suggest that additional genetic events are needed to complement the CALM-AF10 transgene and complete the process of leukemic transformation.
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Affiliation(s)
- David Caudell
- Genetics Branch, National Cancer Institute, National Institutes for Health, Bethesda, MD
- Comparative Molecular Pathology Unit, National Cancer Institute, National Institutes for Health, Bethesda, MD
- Department of Veterinary Medical Sciences, University of Maryland, College Park, MD
| | - Zhenhua Zhang
- Genetics Branch, National Cancer Institute, National Institutes for Health, Bethesda, MD
| | - Yang Jo Chung
- Genetics Branch, National Cancer Institute, National Institutes for Health, Bethesda, MD
| | - Peter D. Aplan
- Genetics Branch, National Cancer Institute, National Institutes for Health, Bethesda, MD
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59
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Wong P, Iwasaki M, Somervaille TCP, So CWE, So CWE, Cleary ML. Meis1 is an essential and rate-limiting regulator of MLL leukemia stem cell potential. Genes Dev 2007; 21:2762-74. [PMID: 17942707 DOI: 10.1101/gad.1602107] [Citation(s) in RCA: 225] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Oncogenic mutations of the MLL histone methyltransferase confer an unusual ability to transform non-self-renewing myeloid progenitors into leukemia stem cells (LSCs) by mechanisms that remain poorly defined. Misregulation of Hox genes is likely to be critical for LSC induction and maintenance but alone it does not recapitulate the phenotype and biology of MLL leukemias, which are clinically heterogeneous--presumably reflecting differences in LSC biology and/or frequency. TALE (three-amino-acid loop extension) class homeodomain proteins of the Pbx and Meis families are also misexpressed in this context, and we thus employed knockout, knockdown, and dominant-negative genetic techniques to investigate the requirements and contributions of these factors in MLL oncoprotein-induced acute myeloid leukemia. Our studies show that induction and maintenance of MLL transformation requires Meis1 and is codependent on the redundant contributions of Pbx2 and Pbx3. Meis1 in particular serves a major role in establishing LSC potential, and determines LSC frequency by quantitatively regulating the extent of self-renewal, differentiation arrest, and cycling, as well as the rate of in vivo LSC generation from myeloid progenitors. Thus, TALE proteins are critical downstream effectors within an essential homeoprotein network that serves a rate-limiting regulatory role in MLL leukemogenesis.
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Affiliation(s)
- Piu Wong
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
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60
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Prima V, Hunger SP. Cooperative transformation by MEF2D/DAZAP1 and DAZAP1/MEF2D fusion proteins generated by the variant t(1;19) in acute lymphoblastic leukemia. Leukemia 2007; 21:2470-5. [PMID: 17898785 DOI: 10.1038/sj.leu.2404962] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A variant t(1;19)(q23;p13.3) translocation creates reciprocal DAZAP1/MEF2D and MEF2D/DAZAP1 fusion genes that are expressed in acute lymphoblastic leukemia. We used retroviral gene transfer to ectopically express wild-type and chimeric DAZAP1 and MEF2D fusion proteins in NIH 3T3 cells. In soft agar assays, each of the fusion proteins transformed 3T3 cells with a 20-fold increase in colony formation as compared to empty vector or native MEF2D or DAZAP1 proteins. Co-expression of both DAZAP1/MEF2D and MEF2D/DAZAP1 led to a threefold increase in colony formation as compared to either fusion protein alone. Expression of wild-type DAZAP1, MEF2D or DAZAP1/MEF2D allowed 3T3 cells to proliferate under low serum (0.5%) conditions and suppressed apoptosis. In contrast, MEF2D/DAZAP1 expression did not facilitate proliferation in low serum and led to a modest increase in apoptosis. Both MEF2D/DAZAP1 and DAZAP1/MEF2D have oncogenic properties, and co-expression of both fusion proteins is synergistic.
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MESH Headings
- Animals
- Apoptosis/physiology
- Cell Adhesion
- Cell Shape
- Cell Transformation, Neoplastic/genetics
- Chromosomes, Human, Pair 1/genetics
- Chromosomes, Human, Pair 1/ultrastructure
- Chromosomes, Human, Pair 19/genetics
- Chromosomes, Human, Pair 19/ultrastructure
- Culture Media, Serum-Free/pharmacology
- Humans
- MADS Domain Proteins/genetics
- MEF2 Transcription Factors
- Mice
- Myogenic Regulatory Factors/genetics
- NIH 3T3 Cells
- Oncogene Proteins, Fusion/biosynthesis
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/physiology
- RNA-Binding Proteins/genetics
- Recombinant Fusion Proteins/physiology
- Transduction, Genetic
- Translocation, Genetic
- Tumor Stem Cell Assay
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Affiliation(s)
- V Prima
- Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL 32610-3633, USA.
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61
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Kowarz E, Burmeister T, Lo Nigro L, Jansen MWJC, Delabesse E, Klingebiel T, Dingermann T, Meyer C, Marschalek R. Complex MLL rearrangements in t(4;11) leukemia patients with absent AF4 · MLL fusion allele. Leukemia 2007; 21:1232-8. [PMID: 17410185 DOI: 10.1038/sj.leu.2404686] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The human mixed lineage leukemia (MLL) gene is frequently involved in genetic rearrangements with more than 55 different translocation partner genes, all associated with acute leukemia. Reciprocal chromosomal translocations generate two MLL fusion alleles, where 5'- and 3'-portions of MLL are fused to gene segments of given fusion partners. In case of t(4;11) patients, about 80% of all patients exhibit both reciprocal fusion alleles, MLL.AF4 and AF4.MLL, respectively. By contrast, 20% of all t(4;11) patients seem to encode only the MLL.AF4 fusion allele. Here, we analyzed these 'MLL.AF4(+)/AF4.MLL(-)' patients at the genomic DNA level to unravel their genetic situation. Cryptic translocations and three-way translocations were found in this group of t(4;11) patients. Reciprocal MLL fusions with novel translocation partner genes, for example NF-KB1 and RABGAP1L, were identified and actively transcribed in leukemic cells. In other patients, the reciprocal 3'-MLL gene segment was fused out-of-frame to PBX1, ELF2, DSCAML1 and FXYD6. The latter rearrangements caused haploinsufficiency of genes that are normally expressed in hematopoietic cells. Finally, patients were identified that encode only solitary 3'-MLL gene segments on the reciprocal allele. Based on these data, we propose that all t(4;11) patients exhibit reciprocal MLL alleles, but due to the individual recombination events, provide different pathological disease mechanisms.
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Affiliation(s)
- E Kowarz
- Institute of Pharmaceutical Biology, ZAFES, DCAL, JWG-University Frankfurt, Biocenter, Frankfurt, Main, Germany
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62
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Bitoun E, Oliver PL, Davies KE. The mixed-lineage leukemia fusion partner AF4 stimulates RNA polymerase II transcriptional elongation and mediates coordinated chromatin remodeling. Hum Mol Genet 2007; 16:92-106. [PMID: 17135274 DOI: 10.1093/hmg/ddl444] [Citation(s) in RCA: 239] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AF4 gene, frequently translocated with mixed-lineage leukemia (MLL) in childhood acute leukemia, encodes a putative transcriptional activator of the AF4/LAF4/FMR2 (ALF) protein family previously implicated in lymphopoiesis and Purkinje cell function in the cerebellum. Here, we provide the first evidence for a direct role of AF4 in the regulation of transcriptional elongation by RNA polymerase II (Pol II). We demonstrate that mouse Af4 functions as a positive regulator of Pol II transcription elongation factor b (P-TEFb) kinase and, in complex with MLL fusion partners Af9, Enl and Af10, as a mediator of histone H3-K79 methylation by recruiting Dot1 to elongating Pol II. These pathways are interconnected and tightly regulated by the P-TEFb-dependent phosphorylation of Af4, Af9 and Enl which controls their transactivation activity and/or protein stability. Consistently, increased levels of phosphorylated Pol II and methylated H3-K79 are observed in the ataxic mouse mutant robotic, an over-expression model of Af4. Finally, we confirm the functional relevance of Af4, Enl and Af9 to the regulation of gene transcription as their over-expression strongly stimulates P-TEFb-dependent transcription of a luciferase reporter gene. Our findings uncover a central role for these proteins in the regulation of transcriptional elongation and coordinated histone methylation, providing valuable insight into their contribution to leukemogenesis and neurodegeneration. Since these activities likely extend to the entire ALF protein family, this study also significantly inputs our understanding of the molecular basis of FRAXE mental retardation syndrome in which FMR2 expression is silenced.
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Affiliation(s)
- Emmanuelle Bitoun
- Department of Physiology, Anatomy and Genetics, Medical Research Council Functional Genetics Unit, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
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63
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Lindsey S, Huang W, Wang H, Horvath E, Zhu C, Eklund EA. Activation of SHP2 Protein-tyrosine Phosphatase Increases HoxA10-induced Repression of the Genes Encoding gp91PHOX and p67PHOX. J Biol Chem 2007; 282:2237-49. [PMID: 17138561 DOI: 10.1074/jbc.m608642200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The CYBB and NCF2 genes encode the phagocyte oxidase proteins gp91(PHOX) and p67(PHOX), respectively. These genes are transcribed after the promyelocyte stage of differentiation, and transcription continues until cell death. In undifferentiated myeloid cells, homologous cis-elements in the CYBB and NCF2 genes are repressed by the homeodomain transcription factor HoxA10. During cytokine-induced myelopoiesis, tyrosine phosphorylation of HoxA10 decreases binding affinity for the CYBB and NCF2 cis-elements. This abrogates HoxA10-induced transcriptional repression as differentiation proceeds. Therefore, mechanisms involved in differentiation stage-specific HoxA10 tyrosine phosphorylation are of interest because HoxA10 phosphorylation modulates myeloid-specific gene transcription. In this study, we found that HoxA10 is a substrate for SHP2 protein-tyrosine phosphatase in undifferentiated myeloid cells. In contrast, HoxA10 is a substrate for a constitutively active mutant form of SHP2 in both undifferentiated and differentiating myeloid cells. Expression of such SHP2 mutants results in persistent HoxA10 repression of CYBB and NCF2 transcription during myelopoiesis. Both HoxA10 overexpression and activating SHP2 mutations have been described in human myeloid malignancies. Therefore, our results suggest that these mutations could cooperate, leading to decreased myeloid-specific gene transcription and functional differentiation block in myeloid cells with both defects.
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Affiliation(s)
- Stephan Lindsey
- Feinberg School of Medicine and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, Illinois 60611, USA
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64
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Strehl S, König M, Meyer C, Schneider B, Harbott J, Jäger U, von Bergh ARM, Loncarevic IF, Jarosova M, Schmidt HH, Moore SDP, Marschalek R, Haas OA. Molecular dissection of t(11;17) in acute myeloid leukemia reveals a variety of gene fusions with heterogeneous fusion transcripts and multiple splice variants. Genes Chromosomes Cancer 2006; 45:1041-9. [PMID: 16897742 DOI: 10.1002/gcc.20372] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The majority of translocations that involve the long arms of chromosomes 11 and 17 in acute myeloid leukemia appear identical on the cytogenetic level. Nevertheless, they are diverse on the molecular level. At present, two genes are known in 11q23 and four in 17q12-25 that generate five distinct fusion genes: MLL-MLLT6/AF17, MLL-LASP1, MLL-ACACA or MLL-SEPT9/MSF, and ZBTB16/PLZF-RARA. We analyzed 14 cases with a t(11;17) by fluorescence in situ hybridization and molecular genetic techniques and determined the molecular characteristics of their fusion genes. We identified six different gene fusions that comprised seven cases with a MLL-MLLT6/AF17, three with a MLL-SEPT9/MSF, and one each with MLL-LASP1, MLL-ACACA, and ZBTB16/PLZF-RARA fusions. In the remaining case, a MLL-SEPT6/Xq24 fusion suggested a complex rearrangement. The MLL-MLLT6/AF17 transcripts were extremely heterogeneous and the detection of seven different in-frame transcript and splice variants enabled us to predict the protein domains relevant for leukemogenesis. The putative MLL-MLLT6 consensus chimeric protein consists of the AT-hook DNA-binding, the methyltransferase, and the CXXC zinc-finger domains of MLL and the highly conserved octapeptide and the leucine-zipper dimerization motifs of MLLT6. The MLL-SEPT9 transcripts showed a similar high degree of variability. These analyses prove that the diverse types of t(11;17)-associated fusion genes can be reliably identified and delineated with a proper combination of cytogenetic and molecular genetic techniques. The heterogeneity of transcripts encountered in cases with MLL-MLLT6/AF17 and MLL-SEPT9/MSF fusions clearly demonstrates that thorough attention has to be paid to the appropriate selection of primers to cover all these hitherto unrecognized fusion variants.
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MESH Headings
- Adolescent
- Adult
- Aged
- Alternative Splicing
- Child
- Child, Preschool
- Chromosomes, Human, Pair 11
- Chromosomes, Human, Pair 17
- DNA-Binding Proteins/genetics
- Female
- Histone-Lysine N-Methyltransferase
- Homeodomain Proteins/genetics
- Humans
- In Situ Hybridization
- Infant
- Leukemia, Monocytic, Acute/genetics
- Leukemia, Myelomonocytic, Acute/genetics
- Male
- Middle Aged
- Myeloid-Lymphoid Leukemia Protein/genetics
- Neoplasm Proteins/genetics
- Oncogene Proteins, Fusion/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Translocation, Genetic
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Affiliation(s)
- Sabine Strehl
- CCRI, Children's Cancer Research Institute, Kinderspitalgasse 6, Vienna, Austria.
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65
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Somervaille TCP, Cleary ML. Identification and characterization of leukemia stem cells in murine MLL-AF9 acute myeloid leukemia. Cancer Cell 2006; 10:257-68. [PMID: 17045204 DOI: 10.1016/j.ccr.2006.08.020] [Citation(s) in RCA: 439] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Revised: 07/27/2006] [Accepted: 08/28/2006] [Indexed: 11/27/2022]
Abstract
Using a mouse model of human acute myeloid leukemia (AML) induced by the MLL-AF9 oncogene, we demonstrate that colony-forming cells (CFCs) in the bone marrow and spleen of leukemic mice are also leukemia stem cells (LSCs). These self-renewing cells (1) are frequent, accounting for 25%-30% of myeloid lineage cells at late-stage disease; (2) generate a phenotypic, morphologic, and functional leukemia cell hierarchy; (3) express mature myeloid lineage-specific antigens; and (4) exhibit altered microenvironmental interactions by comparison with the oncogene-immortalized CFCs that initiated the disease. Therefore, the LSCs responsible for sustaining, expanding, and regenerating MLL-AF9 AML are downstream myeloid lineage cells, which have acquired an aberrant Hox-associated self-renewal program as well as other biologic features of hematopoietic stem cells.
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MESH Headings
- Animals
- Bone Marrow Cells/cytology
- Cell Culture Techniques
- Cell Line, Transformed
- Cell Lineage
- Cell Transformation, Neoplastic
- Coculture Techniques
- Culture Media, Conditioned
- Disease Models, Animal
- Hematopoietic Stem Cell Transplantation
- Hematopoietic Stem Cells/metabolism
- Hematopoietic Stem Cells/pathology
- Humans
- Immunophenotyping
- Leukemia, Experimental/etiology
- Leukemia, Experimental/genetics
- Leukemia, Experimental/pathology
- Leukemia, Myeloid, Acute/blood
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Inbred Strains
- Mice, Transgenic
- Myeloid Cells/pathology
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Proto-Oncogene Proteins c-kit/metabolism
- Retroviridae/genetics
- Spleen/pathology
- Transduction, Genetic
- Transplantation, Homologous
- X-Rays
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Affiliation(s)
- Tim C P Somervaille
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
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66
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Stasevich I, Utskevich R, Kustanovich A, Litvinko N, Savitskaya T, Chernyavskaya S, Saharova O, Aleinikova O. Translocation (10;11)(p12;q23) in childhood acute myeloid leukemia: incidence and complex mechanism. ACTA ACUST UNITED AC 2006; 169:114-20. [PMID: 16938568 DOI: 10.1016/j.cancergencyto.2006.03.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 03/13/2006] [Accepted: 03/15/2006] [Indexed: 11/30/2022]
Abstract
Using both conventional and molecular cytogenetic methods, we found five new cases of t(10;11)(p12;q23). This translocation represented 28% of all cases of childhood AML treated at our center in 2004, and 63% of AML with rearrangements of 11q23. We describe three mechanisms for the translocation. Different fragments of 11q were involved in four of the five cases. One patient showed a cytogenetically cryptic insertion of 5' part of MLL into the 3' part of MLLT10 in 10p12. The median event-free survival of patients was 8.1 months, and we conclude that the t(10;11)(p12;q23) is associated with unfavorable prognosis in childhood acute myeloid leukemia.
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Affiliation(s)
- Irina Stasevich
- Research Center for Pediatric Oncology and Hematology, 223040, Minsk Region, p. Lesnoi, Belarus.
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67
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Okada Y, Jiang Q, Lemieux M, Jeannotte L, Su L, Zhang Y. Leukaemic transformation by CALM-AF10 involves upregulation of Hoxa5 by hDOT1L. Nat Cell Biol 2006; 8:1017-24. [PMID: 16921363 PMCID: PMC4425349 DOI: 10.1038/ncb1464] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2006] [Accepted: 07/23/2006] [Indexed: 12/16/2022]
Abstract
Chromosomal translocation is a common cause of leukaemia and the most common chromosome translocations found in leukaemia patients involve the mixed lineage leukaemia (MLL) gene. AF10 is one of more than 30 MLL fusion partners in leukaemia. We have recently demonstrated that the H3K79 methyltransferase hDOT1L contributes to MLL-AF10-mediated leukaemogenesis through its interaction with AF10 (ref. 5). In addition to MLL, AF10 has also been reported to fuse to CALM (clathrin-assembly protein-like lymphoid-myeloid) in patients with T-cell acute lymphoblastic leukaemia (T-ALL) and acute myeloid leukaemia (AML). Here, we analysed the molecular mechanism of leukaemogenesis by CALM-AF10. We demonstrate that CALM-AF10 fusion is both necessary and sufficient for leukaemic transformation. Additionally, we provide evidence that hDOT1L has an important role in the transformation process. hDOT1L contributes to CALM-AF10-mediated leukaemic transformation by preventing nuclear export of CALM-AF10 and by upregulating the Hoxa5 gene through H3K79 methylation. Thus, our study establishes CALM-AF10 fusion as a cause of leukaemia and reveals that mistargeting of hDOT1L and upregulation of Hoxa5 through H3K79 methylation is the underlying mechanism behind leukaemia caused by CALM-AF10 fusion.
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Affiliation(s)
- Yuki Okada
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–7295, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–7295, USA
| | - Qi Jiang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–7295, USA
- Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–7295, USA
| | - Margot Lemieux
- Centre de Recherche de L’Hotel-Dieu de Quebec, 9 rue McMahon, Quebec, QC G1R 2J6, Canada
| | - Lucie Jeannotte
- Centre de Recherche de L’Hotel-Dieu de Quebec, 9 rue McMahon, Quebec, QC G1R 2J6, Canada
| | - Lishan Su
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–7295, USA
- Department of Microbiology & Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–7295, USA
| | - Yi Zhang
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–7295, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–7295, USA
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–7295, USA
- Correspondence should be addressed to Y.Z. ()
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68
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Kong CT, Sham MH, So CWE, Cheah KSE, Chen SJ, Chan LC. The Mll-Een knockin fusion gene enhances proliferation of myeloid progenitors derived from mouse embryonic stem cells and causes myeloid leukaemia in chimeric mice. Leukemia 2006; 20:1829-39. [PMID: 16888613 DOI: 10.1038/sj.leu.2404342] [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: 11/08/2022]
Abstract
Rearrangement of the mixed lineage leukaemia (MLL) gene with extra eleven nineteen (EEN) was previously identified in an infant with acute myeloid leukaemia. Using homologous recombination, we have created a mouse equivalent of the human MLL-EEN allele and showed that when Mll(Een/+) embryonic stem (ES) cells were induced to differentiate in vitro into haemopoietic cells, there was increased proliferation of myeloid progenitors with self-renewal property. We also generated Mll(Een/+) chimeric mice, which developed leukaemia displaying enlarged livers, spleens, thymuses and lymph nodes owing to infiltration of Mll(Een/+)-expressing leukemic cells. Immunophenotyping of cells from enlarged organs and bone marrow (BM) of the Mll(Een/+) chimeras revealed an accumulation of Mac-1+/Gr-1- immature myeloid cells and a reduction in normal B- and T-cell populations. We observed differential regulation of Hox genes between myeloid cells derived from Mll(Een/+) ES cells and mouse BM leukemic cells which suggested different waves of Hox expression may be activated by MLL fusion proteins for initiation (in ES cells) and maintenance (in leukemic cells) of the disease. We believe studies of MLL fusion proteins in ES cells combined with in vivo animal models offer new approaches to the dissection of molecular events in multistep pathogenesis of leukaemia.
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Affiliation(s)
- C T Kong
- SH Ho Foundation Research Laboratories in the Department of Pathology, Hong Kong Jockey Club Clinical Research Centre, Hong Kong SAR, China
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69
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Sindt A, Deau B, Brahim W, Staal A, Visanica S, Villarese P, Rault JP, Macintyre E, Delabesse E. Acute monocytic leukemia with coexpression of minor BCR-ABL1 and PICALM-MLLT10 fusion genes along with overexpression of HOXA9. Genes Chromosomes Cancer 2006; 45:575-82. [PMID: 16518848 DOI: 10.1002/gcc.20320] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The t(9;22)(q34;q11) translocation occurs in chronic myeloid leukemia (CML) and adult B-cell acute lymphoblastic leukemia (ALL), leading to fusion of BCR to ABL1 and constitutive activation of ABL1 tyrosine kinase activity. The main BCR-ABL1 breakpoints result in P190 BCR-ABL1 or P210 BCR-ABL1 fusion proteins. The latter is found in almost all cases of CML and in one third of the cases of t(9;22)-positive adult B-ALL. P190 BCR-ABL1 is found in the remaining two thirds of t(9;22)-positive adult B-ALL cases but only exceptionally in CML. We describe here the first case of t(9;22)(q34;q11) associated with t(10;11)(p13;q14) in acute monocytic leukemia. The recurrent t(10;11)(p13;q14) translocation, usually found in acute myeloid leukemia (AML) and T-ALL, merges PICALM to MLLT10. RT-PCR enabled identification of PICALM-MLLT10 and BCR-ABL1 e1-a2 fusion transcripts; in the context of chronic and acute myeloid leukemia, the latter usually has a monocytic presentation. We also identified overexpression of HOXA9, a gene essential to myeloid differentiation that is expressed in PICALM-MLLT10 and MLL-rearranged acute leukemias. This case fits with and extends a recently proposed multistage AML model in which constitutive activation of tyrosine kinases by mutations (BCR-ABL1) are associated with deregulation of transcription factors central to myeloid differentiation (HOXA9 secondary to PICALM-MLLT10).
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MESH Headings
- Adolescent
- Bone Marrow/metabolism
- Follow-Up Studies
- Fusion Proteins, bcr-abl/genetics
- Fusion Proteins, bcr-abl/metabolism
- Gene Expression Regulation, Neoplastic
- Gene Fusion
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Humans
- In Situ Hybridization, Fluorescence
- Karyotyping
- Leukemia, Monocytic, Acute/genetics
- Leukemia, Monocytic, Acute/metabolism
- Male
- Metaphase
- Models, Genetic
- Monomeric Clathrin Assembly Proteins/genetics
- Monomeric Clathrin Assembly Proteins/metabolism
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Phenotype
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Translocation, Genetic
- fms-Like Tyrosine Kinase 3/genetics
- fms-Like Tyrosine Kinase 3/metabolism
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Affiliation(s)
- Audrey Sindt
- Department of Biochemistry and Genetics, CHU Brabois, Nancy, France
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70
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Cui M, Kim EB, Han M. Diverse chromatin remodeling genes antagonize the Rb-involved SynMuv pathways in C. elegans. PLoS Genet 2006; 2:e74. [PMID: 16710447 PMCID: PMC1463046 DOI: 10.1371/journal.pgen.0020074] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 03/29/2006] [Indexed: 01/05/2023] Open
Abstract
In Caenorhabditis elegans, vulval cell-fate specification involves the activities of multiple signal transduction and regulatory pathways that include a receptor tyrosine kinase/Ras/mitogen-activated protein kinase pathway and synthetic multivulva (SynMuv) pathways. Many genes in the SynMuv pathways encode transcription factors including the homologs of mammalian Rb, E2F, and components of the nucleosome-remodeling deacetylase complex. To further elucidate the functions of the SynMuv genes, we performed a genome-wide RNA interference (RNAi) screen to search for genes that antagonize the SynMuv gene activities. Among those that displayed a varying degree of suppression of the SynMuv phenotype, 32 genes are potentially involved in chromatin remodeling (called SynMuv suppressor genes herein). Genetic mutations of two representative genes (zfp-1 and mes-4) were used to further characterize their positive roles in vulval induction and relationships with Ras function. Our analysis revealed antagonistic roles of the SynMuv suppressor genes and the SynMuv B genes in germline-soma distinction, RNAi, somatic transgene silencing, and tissue specific expression of pgl-1 and the lag-2/Delta genes. The opposite roles of these SynMuv B and SynMuv suppressor genes on transcriptional regulation were confirmed in somatic transgene silencing. We also report the identifications of ten new genes in the RNAi pathway and six new genes in germline silencing. Among the ten new RNAi genes, three encode homologs of proteins involved in both protein degradation and chromatin remodeling. Our findings suggest that multiple chromatin remodeling complexes are involved in regulating the expression of specific genes that play critical roles in developmental decisions.
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Affiliation(s)
- Mingxue Cui
- Howard Hughes Medical Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - E. Bridget Kim
- Howard Hughes Medical Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - Min Han
- Howard Hughes Medical Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
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71
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Metzler M, Forster A, Pannell R, Arends MJ, Daser A, Lobato MN, Rabbitts TH. A conditional model of MLL-AF4 B-cell tumourigenesis using invertor technology. Oncogene 2006; 25:3093-103. [PMID: 16607274 DOI: 10.1038/sj.onc.1209636] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
MLL-AF4 fusion is the most common consequence of chromosomal translocations in infant leukaemia and is associated with a poor prognosis. MLL-AF4 is thought to be required in haematopoietic stem cells to elicit leukaemia and may be involved in tumour phenotype specification as it is only found in B-cell tumours in humans. We have employed the invertor conditional technology to create a model of MLL-AF4, in which a floxed AF4 cDNA was knocked into Mll in the opposite orientation for transcription. Cell-specific Cre expression was used to generate Mll-AF4 expression. The mice develop exclusively B-cell lineage neoplasias, whether the Cre gene was controlled by B- or T-cell promoters, but of a more mature phenotype than normally observed in childhood leukaemia. These findings show that the MLL-AF4 fusion protein does not have a mandatory role in multi-potent haematopoietic stem cells to cause cancer and indicates that MLL-AF4 has an instructive function in the phenotype of the tumour.
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MESH Headings
- Animals
- B-Lymphocytes/metabolism
- B-Lymphocytes/pathology
- Cell Lineage
- Cell Transformation, Neoplastic
- Female
- Genes, Lethal
- Homeodomain Proteins/genetics
- Homeodomain Proteins/physiology
- Humans
- Integrases/metabolism
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/pathology
- Lymphoma, Large B-Cell, Diffuse/genetics
- Lymphoma, Large B-Cell, Diffuse/pathology
- Male
- Mice
- Mice, Inbred C57BL
- Myeloid-Lymphoid Leukemia Protein/genetics
- Myeloid-Lymphoid Leukemia Protein/physiology
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/physiology
- Phenotype
- T-Lymphocytes/metabolism
- T-Lymphocytes/pathology
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Affiliation(s)
- M Metzler
- MRC Laboratory of Molecular Biology, Cambridge, UK
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72
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Linggi BE, Brandt SJ, Sun ZW, Hiebert SW. Translating the histone code into leukemia. J Cell Biochem 2006; 96:938-50. [PMID: 16167339 DOI: 10.1002/jcb.20604] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The "histone code" is comprised of the covalent modifications of histone tails that function to regulate gene transcription. The post-translational modifications that occur in histones within the regulatory regions of genes include acetylation, methylation, phosphorylation, ubiquitination, sumoylation, and ADP-ribosylation. These modifications serve to alter chromatin structure and accessibility, and to act as docking sites for transcription factors or other histone modifying enzymes. Several of the factors that are disrupted by chromosomal translocations associated with hematological malignancies can alter the histone code in a gene-specific manner. Here, we discuss how the histone code may be disrupted by chromosomal translocations, either directly by altering the activity of histone modifying enzymes, or indirectly by recruitment of this type of enzyme by oncogenic transcription factors. These alterations in the histone code may alter gene expression pattern to set the stage for leukemogenesis.
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Affiliation(s)
- Bryan E Linggi
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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73
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Archangelo LF, Gläsner J, Krause A, Bohlander SK. The novel CALM interactor CATS influences the subcellular localization of the leukemogenic fusion protein CALM/AF10. Oncogene 2006; 25:4099-109. [PMID: 16491119 DOI: 10.1038/sj.onc.1209438] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The Clathrin Assembly Lymphoid Myeloid leukemia gene (CALM or PICALM) was first identified as the fusion partner of AF10 in the t(10;11)(p13;q14) translocation, which is observed in acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL) and malignant lymphoma. The CALM/AF10 fusion protein plays a crucial role in t(10;11)(p13;q14) associated leukemogenesis. Using the N-terminal half of CALM as a bait in a yeast two-hybrid screen, a novel protein named CATS (CALM interacting protein expressed in thymus and spleen) was identified. Multiple tissue Northern blot analysis showed predominant expression of CATS in thymus, spleen and colon. CATS codes for two protein isoforms of 238 and 248 amino acids (aa). The interaction between CALM and CATS could be confirmed using pull down assays, co-immunoprecipitation and colocalization experiments. The CATS interaction domain of CALM was mapped to aa 221-335 of CALM. This domain is contained in the CALM/AF10 fusion protein. CATS localizes to the nucleus and shows a preference for nucleoli. Expression of CATS was able to markedly increase the nuclear localization of CALM and of the leukemogenic fusion protein CALM/AF10. The possible implications of these findings for CALM/AF10-mediated leukemogenesis are discussed.
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MESH Headings
- 3T3 Cells
- Active Transport, Cell Nucleus/genetics
- Animals
- Base Sequence
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cell Nucleolus/genetics
- Cell Nucleolus/metabolism
- Cell Transformation, Neoplastic/genetics
- Chromosomes, Human, Pair 10/genetics
- Chromosomes, Human, Pair 10/metabolism
- Chromosomes, Human, Pair 13/genetics
- Chromosomes, Human, Pair 13/metabolism
- Gene Expression Regulation/genetics
- Humans
- Intracellular Signaling Peptides and Proteins
- Mice
- Molecular Sequence Data
- Monomeric Clathrin Assembly Proteins/genetics
- Monomeric Clathrin Assembly Proteins/metabolism
- Nuclear Proteins
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Organ Specificity
- Protein Binding/genetics
- Translocation, Genetic/genetics
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Affiliation(s)
- L Fröhlich Archangelo
- Department of Medicine III, University of Munich Hospital Grosshadern, Marchioninistr, Munich, Germany
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74
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Dik WA, Brahim W, Braun C, Asnafi V, Dastugue N, Bernard OA, van Dongen JJM, Langerak AW, Macintyre EA, Delabesse E. CALM-AF10+ T-ALL expression profiles are characterized by overexpression of HOXA and BMI1 oncogenes. Leukemia 2005; 19:1948-57. [PMID: 16107895 DOI: 10.1038/sj.leu.2403891] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The t(10;11)(p13;q14-21) is found in T-ALL and acute myeloid leukemia and fuses CALM (Clathrin-Assembly protein-like Lymphoid-Myeloid leukaemia gene) to AF10. In order to gain insight into the transcriptional consequences of this fusion, microarray-based comparison of CALM-AF10+ vs CALM-AF10- T-ALL was performed. This analysis showed upregulation of HOXA5, HOXA9, HOXA10 and BMI1 in the CALM-AF10+ cases. Microarray results were validated by quantitative RT-PCR on an independent group of T-ALL and compared to mixed lineage leukemia-translocated acute leukemias (MLL-t AL). The overexpression of HOXA genes was associated with overexpression of its cofactor MEIS1 in CALM-AF10+ T-ALL, reaching levels of expression similar to those observed in MLL-t AL. Consequently, CALM-AF10+ T-ALL and MLL-t AL share a specific HOXA overexpression, indicating they activate common oncogenic pathways. In addition, BMI1, located close to AF10 breakpoint, was overexpressed only in CALM-AF10+ T-ALL and not in MLL-t AL. BMI1 controls cellular proliferation through suppression of the tumor suppressors encoded by the CDKN2A locus. This locus, often deleted in T-ALL, was conserved in CALM-AF10+ T-ALL. This suggests that decreased CDKN2A activity, as a result of BMI1 overexpression, contributes to leukemogenesis in CALM-AF10+ T-ALL. We propose to define a HOXA+ leukemia group composed of at least MLL-t, CALM-AF10 and HOXA-t AL, which may benefit from adapted management.
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Affiliation(s)
- W A Dik
- Department of Immunology, Erasmus MC, Rotterdam, The Netherlands
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75
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Hayette S, Cornillet-Lefebvre P, Tigaud I, Struski S, Forissier S, Berchet A, Doll D, Gillot L, Brahim W, Delabesse E, Magaud JP, Rimokh R. AF4p12, a human homologue to the furry gene of Drosophila, as a novel MLL fusion partner. Cancer Res 2005; 65:6521-5. [PMID: 16061630 DOI: 10.1158/0008-5472.can-05-1325] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
More than 35 different partner genes with the mixed lineage leukemia (MLL) gene have been cloned from leukemia cells with translocations involving chromosome 11 band q23. In this study, we report on a novel fusion partner of the MLL gene, AF4p12, which we have identified as the human homologue to the furry gene of Drosophila. AF4p12, highly conserved in evolution, encodes a large protein of 3,105 amino acids. The expression of AF4p12 has been preferentially detected in colon, placenta, and brain tissues and in tumor cells of lymphoid origin. We show that the t(4;11)(p12;q23) translocation results in the creation of a chimeric RNA encoding a putative fusion protein containing 1,362 amino acids from the NH2-terminal part of MLL and 712 amino acids from the COOH-terminal part of AF4p12. FLT3 and HOXA9 genes are overexpressed in this leukemia. We found that the COOH-terminal part of AF4p12 fused to MLL contains a leucine zipper motif and exhibits transcriptional activation properties when fused to Gal4 DNA-binding domains in transient transfection assays. The AF4p12 fragment fused to MLL may contribute to the oncogenic activation of MLL, possibly through specific recruitment of the transcriptional machinery.
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MESH Headings
- Aged
- Amino Acid Sequence
- Animals
- Artificial Gene Fusion
- Base Sequence
- Chromosomes, Human, Pair 11/genetics
- Chromosomes, Human, Pair 4/genetics
- DNA-Binding Proteins/biosynthesis
- DNA-Binding Proteins/genetics
- Drosophila/genetics
- Female
- Histone-Lysine N-Methyltransferase
- Humans
- Molecular Sequence Data
- Myeloid-Lymphoid Leukemia Protein
- Neoplasms, Second Primary/genetics
- Oncogene Proteins, Fusion/biosynthesis
- Oncogene Proteins, Fusion/genetics
- Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics
- Protein Structure, Tertiary
- Proto-Oncogenes/genetics
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Recombinant Fusion Proteins/biosynthesis
- Recombinant Fusion Proteins/genetics
- Transcription Factors/biosynthesis
- Transcription Factors/genetics
- Transcriptional Activation
- Translocation, Genetic
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Affiliation(s)
- Sandrine Hayette
- Laboratoire d'Hématologie et de Cytogénétique, Centre Hospitalier Lyon Sud and EA 3737, Pierre-Benite, France.
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76
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Yokoyama A, Somervaille TCP, Smith KS, Rozenblatt-Rosen O, Meyerson M, Cleary ML. The Menin Tumor Suppressor Protein Is an Essential Oncogenic Cofactor for MLL-Associated Leukemogenesis. Cell 2005; 123:207-18. [PMID: 16239140 DOI: 10.1016/j.cell.2005.09.025] [Citation(s) in RCA: 465] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Revised: 08/10/2005] [Accepted: 09/19/2005] [Indexed: 11/21/2022]
Abstract
The Mixed-Lineage Leukemia (MLL) protein is a histone methyltransferase that is mutated in clinically and biologically distinctive subsets of acute leukemia. MLL normally associates with a cohort of highly conserved cofactors to form a macromolecular complex that includes menin, a product of the MEN1 tumor suppressor gene, which is mutated in heritable and sporadic endocrine tumors. We demonstrate here that oncogenic MLL fusion proteins retain an ability to stably associate with menin through a high-affinity, amino-terminal, conserved binding motif and that this interaction is required for the initiation of MLL-mediated leukemogenesis. Furthermore, menin is essential for maintenance of MLL-associated but not other oncogene induced myeloid transformation. Acute genetic ablation of menin reverses aberrant Hox gene expression mediated by MLL-menin promoter-associated complexes, and specifically abrogates the differentiation arrest and oncogenic properties of MLL-transformed leukemic blasts. These results demonstrate that a human oncoprotein is critically dependent on direct physical interaction with a tumor suppressor protein for its oncogenic activity, validate a potential target for molecular therapy, and suggest central roles for menin in altered epigenetic functions underlying the pathogenesis of hematopoietic cancers.
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Affiliation(s)
- Akihiko Yokoyama
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
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77
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Taki T, Akiyama M, Saito S, Ono R, Taniwaki M, Kato Y, Yuza Y, Eto Y, Hayashi Y. The MYO1F, unconventional myosin type 1F, gene is fused to MLL in infant acute monocytic leukemia with a complex translocation involving chromosomes 7, 11, 19 and 22. Oncogene 2005; 24:5191-7. [PMID: 15897884 DOI: 10.1038/sj.onc.1208711] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We analysed a complex translocation involving chromosomes 7, 11, 19 and 22 in infant acute monocytic leukemia, and identified that the MLL gene on 11q23 was fused to the unconventional myosin type 1F, MYO1F, gene on 19p13.2-13.3. MYO1F consists of at least 28 exons and was predicted to encode a 1098-amino-acid with an N-terminal head domain containing both ATP-binding and actin-binding sequences, a neck domain with a single IQ motif, and a tail with TH1, TH2 and SH3 domains. Northern blot analysis of RNAs prepared from multiple tissues showed that the expression of approximately 4-kb transcripts appeared constant in most tissues examined. However, MYO1F was expressed in only three of 22 leukemic cell lines. The MLL-MYO1F fusion protein contains almost the entire MYO1F, however, C-terminal MYO1F has neither the transactivation domain nor the dimerization domain found in various MLL fusion partners. Further analysis of this novel type of MLL fusion protein would provide new insights into leukemogenesis. MYO1F is the fourth partner gene of MLL on 19p13. At the cytogenetic level, it may be difficult to distinguish MLL-ENL, MLL-ELL, MLL-EEN and MLL-MYO1F fusions created by t(11;19)(q23;p13), and it is likely that cases of t(11;19) lacking a known fusion gene may result in this gene fusion.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Cell Line, Tumor
- Chromosomes, Human, Pair 11
- Chromosomes, Human, Pair 19
- Chromosomes, Human, Pair 22
- Chromosomes, Human, Pair 7
- DNA-Binding Proteins/genetics
- Female
- Gene Rearrangement
- Histone-Lysine N-Methyltransferase
- Humans
- Infant
- Leukemia, Monocytic, Acute/genetics
- Molecular Sequence Data
- Myeloid-Lymphoid Leukemia Protein
- Myosin Type I/genetics
- Proto-Oncogenes/genetics
- Transcription Factors/genetics
- Translocation, Genetic
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Affiliation(s)
- Tomohiko Taki
- Department of Molecular Laboratory Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, 465 Kajii-cho Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan
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78
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Abstract
Chromosome translocations disrupting the MLL gene are associated with various hematologic malignancies but are particularly common in infant and secondary therapy-related acute leukemias. The normal MLL-encoded protein is an essential component of a supercomplex with chromatin-modulating activity conferred by histone acetylase and methyltransferase activities, and the protein plays a key role in the developmental regulation of gene expression, including Hox gene expression. In leukemia, this function is subverted by breakage, recombination, and the formation of chimeric fusion with one of many alternative partners. Such MLL translocations result in the replacement of the C-terminal functional domains of MLL with those of a fusion partner, yielding a newly formed MLL chimeric protein with an altered function that endows hematopoietic progenitors with self-renewing and leukemogenic activity. This potent impact of the MLL chimera can be attributed to one of 2 kinds of activity of the fusion partner: direct transcriptional transactivation or dimerization/oligomerization. Key unresolved issues currently being addressed include the set of target genes for MLL fusions, the stem cell of origin for the leukemias, the role of additional secondary mutations, and the origins or etiology of the MLL gene fusions themselves. Further elaboration of the biology of MLL gene-associated leukemia should lead to novel and specific therapeutic strategies.
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Affiliation(s)
- Mariko Eguchi
- Section of Haemato-Oncology, Institute of Cancer Research, London, UK.
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79
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Daser A, Rabbitts TH. The versatile mixed lineage leukaemia gene MLL and its many associations in leukaemogenesis. Semin Cancer Biol 2005; 15:175-88. [PMID: 15826832 DOI: 10.1016/j.semcancer.2005.01.007] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The marked association of abnormalities of chromosome 11 long arm, band q23, with human leukaemia led to the identification of the 11q23 gene called MLL (or HTRX, HRX, TRX1, ALL-1). MLL can become fused with one of a remarkable panoply of genes from other chromosome locations in individual leukaemias, leading to either acute myeloid or lymphoid tumours (hence the name MLL for mixed lineage leukaemia). The unusual finding that a single protein could be involved in both myeloid and lymphoid malignancies and that the truncated protein could do so as a fusion with very disparate partners has prompted studies to define the molecular role of MLL-fusions in leukaemogenesis and to the development of MLL-controlled mouse models of leukaemogenesis. These studies have defined MLL-fusion proteins as regulators of gene expression, controlling such elements as HOX genes, and have indicated a variety of mechanisms by which MLL-fusion proteins contribute to leukaemogenesis.
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Affiliation(s)
- A Daser
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB22QH, UK
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80
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Okada Y, Feng Q, Lin Y, Jiang Q, Li Y, Coffield VM, Su L, Xu G, Zhang Y. hDOT1L Links Histone Methylation to Leukemogenesis. Cell 2005; 121:167-78. [PMID: 15851025 DOI: 10.1016/j.cell.2005.02.020] [Citation(s) in RCA: 629] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Revised: 02/13/2005] [Accepted: 02/17/2005] [Indexed: 12/01/2022]
Abstract
Epigenetic modifications play an important role in human cancer. One such modification, histone methylation, contributes to human cancer through deregulation of cancer-relevant genes. The yeast Dot1 and its human counterpart, hDOT1L, methylate lysine 79 located within the globular domain of histone H3. Here we report that hDOT1L interacts with AF10, an MLL (mixed lineage leukemia) fusion partner involved in acute myeloid leukemia, through the OM-LZ region of AF10 required for MLL-AF10-mediated leukemogenesis. We demonstrate that direct fusion of hDOT1L to MLL results in leukemic transformation in an hDOT1L methyltransferase activity-dependent manner. Transformation by MLL-hDOT1L and MLL-AF10 results in upregulation of a number of leukemia-relevant genes, such as Hoxa9, concomitant with hypermethylation of H3-K79. Our studies thus establish that mistargeting of hDOT1L to Hoxa9 plays an important role in MLL-AF10-mediated leukemogenesis and suggests that the enzymatic activity of hDOT1L may provide a potential target for therapeutic intervention.
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Affiliation(s)
- Yuki Okada
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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81
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Abstract
Chromosomal aberrations that affect the MLL (Mixed Lineage Leukemia) gene at the locus 11q23 are associated with an aggressive subtype of leukemia. These alterations create MLL fusion derivatives with an active transforming potential. This review summarizes recent advances in our knowledge about normal and malignant MLL proteins with special emphasis on epigenetic processes affected by these molecules.
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82
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Ayton PM, Chen EH, Cleary ML. Binding to nonmethylated CpG DNA is essential for target recognition, transactivation, and myeloid transformation by an MLL oncoprotein. Mol Cell Biol 2005; 24:10470-8. [PMID: 15542854 PMCID: PMC529055 DOI: 10.1128/mcb.24.23.10470-10478.2004] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The MLL gene is a frequent target for leukemia-associated chromosomal translocations that generate dominant-acting chimeric oncoproteins. These invariably contain the amino-terminal 1,400 residues of MLL fused with one of a variety of over 30 distinct nuclear or cytoplasmic partner proteins. Despite the consistent inclusion of the MLL amino-terminal region in leukemia oncoproteins, little is known regarding its molecular contributions to MLL-dependent oncogenesis. Using high-resolution mutagenesis, we identified three MLL domains that are essential for in vitro myeloid transformation via mechanisms that do not compromise subnuclear localization. These include the CXXC/Basic domain and two novel domains of unknown function. Point mutations in the CXXC domain that eliminate myeloid transformation by an MLL fusion protein also abolished recognition and binding of nonmethylated CpG DNA sites in vitro and transactivation in vivo. Our results define a critical role for the CXXC DNA binding domain in MLL-associated oncogenesis, most likely via epigenetic recognition of CpG DNA sites within the regulatory elements of target genes.
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Affiliation(s)
- Paul M Ayton
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
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83
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Abstract
Rearrangements of the MLL gene (ALL1, HRX, and Hrtx) located at chromosome band 11q23 are commonly involved in adult and pediatric cases of primary acute leukemias and also found in cases of therapy-related secondary leukemias. Studies on mouse models of MLL translocation and cell lines containing MLL rearrangements showed that the MLL gene linked chromosomal rearrangements to cellular differentiation and tumor tropism. Moreover, recent structural/functional studies on MLL and aberrant MLL proteins provided new clues and suggested that different mechanisms might be included in leukemogenesis by MLL rearrangements. The connection between these different mechanisms will help us understand globally how aberrant MLL oncogenes affect the normal cellular processes at molecular level.
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Affiliation(s)
- Z-Y Li
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, 5 Dong Dan San Tiao, Beijing, PR China
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84
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Perrin L, Dura JM. Molecular genetics of the Alhambra ( Drosophila AF10) complex locus of Drosophila. Mol Genet Genomics 2004; 272:156-61. [PMID: 15258852 DOI: 10.1007/s00438-004-1042-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Accepted: 06/29/2004] [Indexed: 11/25/2022]
Abstract
The Alhambra (Alh) gene is the Drosophila homologue of the human AF10 gene. AF10 has been identified as a fusion partner of MLL, a human homologue of the fly gene trithorax, in infant leukemias. The endogenous function of human AF10 is not known, but may be vital to its role in acute leukemia. This prompted us to analyse Alh function. We describe here the genetic organisation of the Alh locus in D. melanogaster. We show that an independent lethal complementation group encoding a muscle protein (Mlp84B) is located within an Alh intron. We have already shown that the leucine zipper (LZ) domain of ALH activates several Polycomb group-responsive elements. We further demonstrate that the LZ domain on its own bears the Alh vital function, since it is necessary and sufficient for rescue of Alh mutant lethality. Finally, we demonstrate that, in contrast to a previous report, Alh does not affect position-effect variegation.
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Affiliation(s)
- L Perrin
- Institut de Génétique Humaine, CNRS UPR 1142, 141 Rue de la Cardonille, 34396, Montpellier Cedex 5, France
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85
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Morerio C, Rapella A, Rosanda C, Lanino E, Lo Nigro L, Di Cataldo A, Maserati E, Pasquali F, Panarello C. MLL-MLLT10 fusion in acute monoblastic leukemia: variant complex rearrangements and 11q proximal breakpoint heterogeneity. ACTA ACUST UNITED AC 2004; 152:108-12. [PMID: 15262427 DOI: 10.1016/j.cancergencyto.2003.11.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Revised: 11/24/2003] [Accepted: 11/25/2003] [Indexed: 11/25/2022]
Abstract
Cytogenetic studies of acute monoblastic leukemia cases presenting MLL-MLLT10 (alias MLL-AF10) fusion show a broad heterogeneity of chromosomal breakpoints. We present two new pediatric cases (French-American-British type M5) with MLL-MLLT10 fusion, which we studied with fluorescence in situ hybridization. In both we detected a paracentric inversion of the 11q region that translocated onto chromosome 10p12; one case displayed a variant complex pattern. We review the cytogenetic molecular data concerning the proximal inversion breakpoint of 11q and confirm its heterogeneity.
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Affiliation(s)
- Cristina Morerio
- Dipartimento di Ematologia ed Oncologia Pediatrica, Istituto Giannina Gaslini, L.go G. Gaslini 5, 16148 Genova, Italy
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86
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Eguchi M, Eguchi-Ishimae M, Greaves M. The small oligomerization domain of gephyrin converts MLL to an oncogene. Blood 2004; 103:3876-82. [PMID: 14751928 DOI: 10.1182/blood-2003-11-3817] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractThe MLL (mixed lineage leukemia) gene forms chimeric fusions with a diverse set of partner genes as a consequence of chromosome translocations in leukemia. In several fusion partners, a transcriptional activation domain appears to be essential for conferring leukemogenic capacity on MLL protein. Other fusion partners, however, lack such domains. Here we show that gephyrin (GPHN), a neuronal receptor assembly protein and rare fusion partner of MLL in leukemia, has the capacity as an MLL-GPHN chimera to transform hematopoietic progenitors, despite lack of transcriptional activity. A small 15–amino acid tubulin-binding domain of GPHN is necessary and sufficient for this activity in vitro and in vivo. This domain also confers oligomerization capacity on MLL protein, suggesting that such activity may contribute critically to leukemogenesis. The transduction of MLL-GPHN into hematopoietic progenitor cells caused myeloid and lymphoid lineage leukemias in mice, suggesting that MLL-GPHN can target multipotent progenitor cells. Our results, and other recent data, provide a mechanism for oncogenic conversion of MLL by fusion partners encoding cytoplasmic proteins.
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Affiliation(s)
- Mariko Eguchi
- Leukaemia Research Fund Centre, Institute of Cancer Research, Chester Beatty Laboratories, London, United Kingdom
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87
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Abstract
The MLL gene is a major player in leukemia, particularly in infant leukemia and in secondary, therapy-related acute leukemia. The normal MLL gene plays a key role in developmental regulation of gene expression (including HOX genes), and in leukemia this function is subverted by breakage, recombination, and chimeric fusion with one of 40 or more alternative partner genes. In infant leukemias, the chromosome translocations involving MLL arise during fetal hematopoiesis, possibly in a primitive lymphomyeloid stem cell. In general, these leukemias have a very poor prognosis. The malignancy of these leukemias is all the more dramatic considering their very short preclinical natural history or latency. These data raise fundamental issues of how such divergent MLL chimeric genes transform cells, why they so rapidly evolve to a malignant status, and what alternative or novel therapeutic strategies might be considered. We review here progress in tackling these questions.
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MESH Headings
- Acute Disease
- Age of Onset
- Animals
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/therapeutic use
- Cell Transformation, Neoplastic/genetics
- Chromosomes, Human, Pair 11/genetics
- Chromosomes, Human, Pair 11/ultrastructure
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Disease Progression
- Drug Design
- Histone-Lysine N-Methyltransferase
- Humans
- Infant
- Infant, Newborn
- Leukemia, Myeloid/drug therapy
- Leukemia, Myeloid/embryology
- Leukemia, Myeloid/epidemiology
- Leukemia, Myeloid/genetics
- Mice
- Mice, Knockout
- Myeloid-Lymphoid Leukemia Protein
- Oligonucleotide Array Sequence Analysis
- Oncogene Proteins, Fusion/chemistry
- Oncogene Proteins, Fusion/genetics
- Proto-Oncogenes
- Structure-Activity Relationship
- Transcription Factors
- Translocation, Genetic
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Affiliation(s)
- Mariko Eguchi
- LRF Centre for Cell and Molecular Biology of Leukaemia, Institute of Cancer Research, London, UK
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88
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Daser A, Rabbitts TH. Extending the repertoire of the mixed-lineage leukemia gene MLL in leukemogenesis. Genes Dev 2004; 18:965-74. [PMID: 15132992 DOI: 10.1101/gad.1195504] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Angelika Daser
- MRC Laboratory of Molecular Biology, Cambridge CB2 2QH, UK
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89
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Liu H, Chen B, Xiong H, Huang QH, Zhang QH, Wang ZG, Li BL, Chen Z, Chen SJ. Functional contribution of EEN to leukemogenic transformation by MLL-EEN fusion protein. Oncogene 2004; 23:3385-94. [PMID: 15077184 DOI: 10.1038/sj.onc.1207402] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The EEN (extra eleven nineteen) gene was originally cloned from a case of acute myeloid leukemia M5 subtype with translocation t (11; 19)(q23; p13), in which EEN was fused with MLL. To explore the involvement of EEN in leukemogenesis caused by MLL-EEN, we studied the transformation potential of the MLL-EEN fusion protein. MLL-EEN had oncogenic features, while, as a control, MLLDelta, the truncated form of MLL lacking the EEN moiety, did not show any oncogenic potential. MLL-EEN exerted a dominant-negative effect over wild-type EEN in terms of subcellular localization. Normally, EEN was found in the cytoplasm, but the MLL-EEN fusion protein was located in the nucleus, and EEN could be delocalized by MLL-EEN. This interaction is via a coiled-coil dimerization domain of EEN, which is reserved in the fusion protein. In addition, MLL-EEN might act as a potential transcriptional factor with the MLL part providing the DNA-binding domain and the EEN part providing the transcription activation domain, though EEN seems to have no direct role in transcriptional regulation. As an aberrant transcriptional factor, MLL-EEN could transactivate the promoter of HoxA7, a potential target gene of MLL.
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Affiliation(s)
- Han Liu
- State Key Laboratory for Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital affiliated to Shanghai Second Medical University, 197 Ruijin Road II, Shanghai 200025, PR China
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90
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Zeisig BB, Milne T, García-Cuéllar MP, Schreiner S, Martin ME, Fuchs U, Borkhardt A, Chanda SK, Walker J, Soden R, Hess JL, Slany RK. Hoxa9 and Meis1 are key targets for MLL-ENL-mediated cellular immortalization. Mol Cell Biol 2004; 24:617-28. [PMID: 14701735 PMCID: PMC343796 DOI: 10.1128/mcb.24.2.617-628.2004] [Citation(s) in RCA: 262] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MLL fusion proteins are oncogenic transcription factors that are associated with aggressive lymphoid and myeloid leukemias. We constructed an inducible MLL fusion, MLL-ENL-ERtm, that rendered the transcriptional and transforming properties of MLL-ENL strictly dependent on the presence of 4-hydroxy-tamoxifen. MLL-ENL-ERtm-immortalized hematopoietic cells required 4-hydroxy-tamoxifen for continuous growth and differentiated terminally upon tamoxifen withdrawal. Microarray analysis performed on these conditionally transformed cells revealed Hoxa9 and Hoxa7 as well as the Hox coregulators Meis1 and Pbx3 among the targets upregulated by MLL-ENL-ERtm. Overexpression of the Hox repressor Bmi-1 inhibited the growth-transforming activity of MLL-ENL. Moreover, the enforced expression of Hoxa9 in combination with Meis1 was sufficient to substitute for MLL-ENL-ERtm function and to maintain a state of continuous proliferation and differentiation arrest. These results suggest that MLL fusion proteins impose a reversible block on myeloid differentiation through aberrant activation of a limited set of homeobox genes and Hox coregulators that are consistently expressed in MLL-associated leukemias.
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Affiliation(s)
- Bernd B Zeisig
- Department of Genetics, University Erlangen, Staudtstrasse 5, 91058 Erlangen, Germany
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91
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Yam JWP, Jin DY, So CW, Chan LC. Identification and characterization of EBP, a novel EEN binding protein that inhibits Ras signaling and is recruited into the nucleus by the MLL-EEN fusion protein. Blood 2004; 103:1445-53. [PMID: 14551139 DOI: 10.1182/blood-2003-07-2452] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
AbstractThe chimeric MLL-EEN fusion protein is created as a result of chromosomal translocation t(11;19)(q23;p13). EEN, an Src homology 3 (SH3) domain–containing protein in the endophilin family, has been implicated in endocytosis, although little is known about its role in leukemogenesis mediated by the MLL-EEN fusion protein. In this study, we have identified and characterized EBP, a novel EEN binding protein that interacts with the SH3 domain of EEN through a proline-rich motif PPERP. EBP is a ubiquitous protein that is normally expressed in the cytoplasm but is recruited to the nucleus by MLL-EEN with a punctate localization pattern characteristic of the MLL chimeric proteins. EBP interacts simultaneously with EEN and Sos, a guanine-nucleotide exchange factor for Ras. Coexpressoin of EBP with EEN leads to suppression of Ras-induced cellular transformation and Ras-mediated activation of Elk-1. Taken together, our findings suggest a new mechanism for MLL-EEN–mediated leukemogenesis in which MLL-EEN interferes with the Ras-suppressing activities of EBP through direct interaction.
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92
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Abstract
MLL gene fusions are the hallmark of more than 70% of therapy-related leukemias (t-ML) associated with topoisomerase II inhibitors (e.g., etoposide) and cause leukemia in murine transgenic models. To determine whether Mll genomic fusions can occur after exposure to topoisomerase II inhibitors, we developed a long-distance inverse PCR DNA-based assay for chimeric Mll fusions in mouse embryonic stem cells. We detected Mll fusions at a higher frequency following 100 microM etoposide for 8 h (16x10(-6) cell(-1)) than in no-drug controls (1.0x10(-6) cell(-1), P=0.0002) or after treatment with a comparably cytotoxic exposure to the antimicrotubule drug vincristine (1.0x10(-6) cell(-1), P=0.0047). The fusion points in Mll chimeric products induced by etoposide were localized to a 1.5 kb region between exons 9 and 11, analogous to the MLL breakpoint cluster region in human leukemia. All 49 Mll fusion partners analyzed matched known genomic murine sequences, with 40 (82%) matching annotated genes covering eighteen murine autosomes. One partner was Runx1, the murine homologue of the transcription factor AML-1, a target of human translocations in therapy-related leukemia. These findings indicate that etoposide triggers the formation of Mll gene fusions, a critical step for the development of treatment-induced leukemic transformation.
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Affiliation(s)
- Javier G Blanco
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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93
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Ayton PM, Cleary ML. Transformation of myeloid progenitors by MLL oncoproteins is dependent on Hoxa7 and Hoxa9. Genes Dev 2003; 17:2298-307. [PMID: 12952893 PMCID: PMC196466 DOI: 10.1101/gad.1111603] [Citation(s) in RCA: 341] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Transcriptional deregulation through the production of dominant-acting chimeric transcription factors derived from chromosomal translocations is a common theme in the pathogenesis of acute leukemias; however, the essential target genes for acute leukemogenesis are unknown. We demonstrate here that primary myeloid progenitors immortalized by various MLL oncoproteins exhibit a characteristic Hoxa gene cluster expression profile, which reflects that preferentially expressed in the myeloid clonogenic progenitor fraction of normal bone marrow. Continued maintenance of this MLL-dependent Hoxa gene expression profile is associated with conditional MLL-associated myeloid immortalization. Moreover, Hoxa7 and Hoxa9 were specifically required for efficient in vitro myeloid immortalization by an MLL fusion protein but not other leukemogenic fusion proteins. Finally, in a bone marrow transduction/transplantation model, Hoxa9 is essential for MLL-dependent leukemogenesis in vivo, a primary requirement detected at the earliest stages of disease initiation. Thus, a genetic reliance on Hoxa7 and Hoxa9 in MLL-mediated transformation demonstrates a gain-of-function mechanism for MLL oncoproteins as upstream constitutive activators that promote myeloid transformation via a Hox-dependent mechanism.
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Affiliation(s)
- Paul M Ayton
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
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94
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Martin ME, Milne TA, Bloyer S, Galoian K, Shen W, Gibbs D, Brock HW, Slany R, Hess JL. Dimerization of MLL fusion proteins immortalizes hematopoietic cells. Cancer Cell 2003; 4:197-207. [PMID: 14522254 DOI: 10.1016/s1535-6108(03)00214-9] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
MLL fusion proteins are leukemogenic, but their mechanism is unclear. Induced dimerization of a truncated MLL immortalizes bone marrow and imposes a reversible block on myeloid differentiation associated with upregulation of Hox a7, a9, and Meis1. Both dimerized MLL and exon-duplicated MLL are potent transcriptional activators, suggesting a link between dimerization and partial tandem duplication of DNA binding domains of MLL. Dimerized MLL binds with higher affinity than undimerized MLL to a CpG island within the Hox a9 locus. However, MLL-AF9 is not dimerized in vivo. The data support a model in which either MLL dimerization/exon duplication or fusion to a transcriptional activator results in Hox gene upregulation and ultimately transformation.
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Affiliation(s)
- Mary Ellen Martin
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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95
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Jones LK, Neat MJ, van Delft FW, Mitchell MP, Adamaki M, Stoneham SJ, Patel N, Saha V. Cryptic rearrangement involving MLL and AF10 occurring in utero. Leukemia 2003; 17:1667-9. [PMID: 12886258 DOI: 10.1038/sj.leu.2403039] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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96
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So CW, Lin M, Ayton PM, Chen EH, Cleary ML. Dimerization contributes to oncogenic activation of MLL chimeras in acute leukemias. Cancer Cell 2003; 4:99-110. [PMID: 12957285 DOI: 10.1016/s1535-6108(03)00188-0] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
MLL is a histone methyltransferase that can be converted into an oncoprotein by acquisition of transcriptional effector domains following heterologous protein fusions with a variety of nuclear transcription factors, cofactors, or chromatin remodeling proteins in acute leukemias. Here we demonstrate an alternative mechanism for activation of MLL following fusions with proteins (AF1p/Eps15 and GAS7) that normally reside in the cytoplasm. The coiled-coil oligomerization domains of these proteins are necessary and sufficient for leukemogenic transformation induced by the respective MLL fusion proteins. Furthermore, homodimerization of MLL by synthetic dimerization modules mimics bona fide MLL fusion proteins resulting in Hox gene activation and enhanced self-renewal of hematopoietic progenitors. Our studies support an oligomerization-dependent mechanism for oncogenic conversion of MLL, presumably in part by recruitment of accessory factors through the dimerized MLL moiety of the chimeric protein.
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Affiliation(s)
- Chi Wai So
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
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97
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So CW, Karsunky H, Passegué E, Cozzio A, Weissman IL, Cleary ML. MLL-GAS7 transforms multipotent hematopoietic progenitors and induces mixed lineage leukemias in mice. Cancer Cell 2003; 3:161-71. [PMID: 12620410 DOI: 10.1016/s1535-6108(03)00019-9] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A specific association with mixed lineage leukemias suggests that MLL oncoproteins may selectively target early multipotent hematopoietic progenitors or stem cells. We demonstrate here that a representative MLL fusion protein, MLL-GAS7, impairs the differentiation and enhances the in vitro growth of murine hematopoietic cells with multipotent features. The multilineage differentiation potential of these cells was suggested by their immuno-phenotypes and transcriptional programs and confirmed by their ability to induce three pathologically distinct leukemias in mice, including an acute biphenotypic leukemia (ABL) that recapitulates the distinctive hallmark features of many MLL-associated leukemias in humans. This experimental modeling of ABL in mice highlights its origin from multipotential progenitors that arrest at a bipotential stage specifically targeted or induced by MLL oncogenes.
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Affiliation(s)
- Chi Wai So
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
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98
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Abstract
The mixed lineage leukemia (MLL) gene undergoes fusions with a diverse set of genes as a consequence of chromosomal translocations in acute leukemias. Two of these partner genes code for members of the forkhead subfamily of transcription factors designated FKHRL1 and AFX. We demonstrate here that MLL-FKHRL1 enhances the self-renewal of murine myeloid progenitors in vitro and induces acute myeloid leukemias in syngeneic mice. The long latency (mean = 157 days), reduced penetrance, and hematologic features of the leukemias were very similar to those observed for the forkhead fusion protein MLL-AFX and contrasted with the more aggressive features of leukemias induced by MLL-AF10. Transformation mediated by MLL-forkhead fusion proteins required 2 conserved transcriptional effector domains (CR2 and CR3), each of which alone was not sufficient to activate MLL. A synthetic fusion of MLL with FKHR, a third mammalian forkhead family member that contains both effector domains, was also capable of transforming hematopoietic progenitors in vitro. A comparable requirement for 2 distinct transcriptional effector domains was also displayed by VP16, which required its proximal minimal transactivation domain (MTD/H1) and distal H2 domain to activate the oncogenic potential of MLL. The functional importance of CR2 was further demonstrated by its ability to substitute for H2 of VP16 in domain-swapping experiments to confer oncogenic activity on MLL. Our results, based on bona fide transcription factors as partners for MLL, unequivocally establish a transcriptional effector mechanism to activate its oncogenic potential and further support a role for fusion partners in determining pathologic features of the leukemia phenotype.
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Affiliation(s)
- Chi Wai So
- Department of Pathology, Stanford University School of Medicine, CA 94305, USA
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99
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Strehl S, Borkhardt A, Slany R, Fuchs UE, König M, Haas OA. The human LASP1 gene is fused to MLL in an acute myeloid leukemia with t(11;17)(q23;q21). Oncogene 2003; 22:157-60. [PMID: 12527918 DOI: 10.1038/sj.onc.1206042] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The MLL gene at chromosome 11q23 is frequently rearranged in acute leukemia. Here we report the identification of a new MLL fusion partner in the case of an infant with AML-M4 and a t(11;17)(q23;q21) translocation. Fluorescence in situ hybridization (FISH) and RT-PCR analyses indicated a rearrangement of the MLL gene, but no fusion with previously identified MLL fusion partners at 17q, such as AF17 or MSF. Rapid amplification of cDNA ends (RACE) revealed an in-frame fusion of MLL to LASP1, a gene that is amplified and overexpressed in breast cancer. Retroviral transduction of myeloid progenitors demonstrated that MLL/LASP1 is the fourth known fusion of MLL with a cytoplasmic protein that has no in vitro transformation capability, thus establishing a potential subgroup among the MLL fusion proteins.
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Affiliation(s)
- Sabine Strehl
- CCRI, Children's Cancer Research Institute, St. Anna Kinderspital, Vienna, Austria
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100
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Perrin L, Bloyer S, Ferraz C, Agrawal N, Sinha P, Dura JM. The leucine zipper motif of the Drosophila AF10 homologue can inhibit PRE-mediated repression: implications for leukemogenic activity of human MLL-AF10 fusions. Mol Cell Biol 2003; 23:119-30. [PMID: 12482966 PMCID: PMC140655 DOI: 10.1128/mcb.23.1.119-130.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In a screen for Drosophila genes that interfere with transcriptional repression mediated by the Polycomb group of genes, we identified a dominant mutation affecting the Alhambra (Alh) gene, the fly homologue of the human AF10 gene. AF10 has been identified as a fusion partner of both MLL and CALM in infant leukemias. Both fusion proteins retain the leucine zipper domain of AF10 but not its PHD domain. We show here that, while the full-length ALH protein has no activity on Polycomb group-responsive elements (PREs), overexpression of the isolated ALH leucine zipper domain activates several PREs. Within the ALH full-length protein, the PHD domain inhibits the PRE deregulation mediated by the leucine zipper domain. This deregulation is conserved in the human AF10 leucine zipper domain, which confers the same activity on an oncogenic MLL-AF10 fusion protein expressed in Drosophila melanogaster. These data reveal new properties for the leucine zipper domain and thus might provide new clues to understanding the mechanisms by which AF10 fusion proteins in which the PHD domain is lost might trigger leukemias in humans.
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Affiliation(s)
- Laurent Perrin
- Institut de Génétique Humaine, CNRS, UPR 1142, 34396 Montpellier Cedex 5, France.
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