1
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Kao TW, Chen HH, Lin J, Wang TL, Shen YA. PBX1 as a novel master regulator in cancer: Its regulation, molecular biology, and therapeutic applications. Biochim Biophys Acta Rev Cancer 2024; 1879:189085. [PMID: 38341110 DOI: 10.1016/j.bbcan.2024.189085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 01/31/2024] [Accepted: 02/05/2024] [Indexed: 02/12/2024]
Abstract
PBX1 is a critical transcription factor at the top of various cell fate-determining pathways. In cancer, PBX1 stands at the crossroads of multiple oncogenic signaling pathways and mediates responses by recruiting a broad repertoire of downstream targets. Research thus far has corroborated the involvement of PBX1 in cancer proliferation, resisting apoptosis, tumor-associated neoangiogenesis, epithelial-mesenchymal transition (EMT) and metastasis, immune evasion, genome instability, and dysregulating cellular metabolism. Recently, our understanding of the functional regulation of the PBX1 protein has advanced, as increasing evidence has depicted a regulatory network consisting of transcriptional, post-transcriptional, and post-translational levels of control mechanisms. Furthermore, accumulating studies have supported the clinical utilization of PBX1 as a prognostic or therapeutic target in cancer. Preliminary results showed that PBX1 entails vast potential as a targetable master regulator in the treatment of cancer, particularly in those with high-risk features and resistance to other therapeutic strategies. In this review, we will explore the regulation, protein-protein interactions, molecular pathways, clinical application, and future challenges of PBX1.
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Affiliation(s)
- Ting-Wan Kao
- Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110301, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 110301, Taiwan
| | - Hsiao-Han Chen
- Department of General Medicine, National Taiwan University Hospital, Taipei 100224, Taiwan
| | - James Lin
- School of Medicine, College of Medicine, Taipei Medical University, Taipei 110301, Taiwan
| | - Tian-Li Wang
- Departments of Pathology, Oncology and Gynecology and Obstetrics, Johns Hopkins Medical Institutions, 1550 Orleans Street, CRB2, Room 306, Baltimore, MD 21231, USA; Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Yao-An Shen
- Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110301, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 110301, Taiwan; International Master/Ph.D. Program in Medicine, College of Medicine, Taipei Medical University, Taipei 110301, Taiwan.
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2
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Johannessen JA, Formica M, Haukeland ALC, Bråthen NR, Al Outa A, Aarsund M, Therrien M, Enserink JM, Knævelsrud H. The human leukemic oncogene MLL-AF4 promotes hyperplastic growth of hematopoietic tissues in Drosophila larvae. iScience 2023; 26:107726. [PMID: 37720104 PMCID: PMC10504488 DOI: 10.1016/j.isci.2023.107726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 06/25/2023] [Accepted: 08/21/2023] [Indexed: 09/19/2023] Open
Abstract
MLL-rearranged (MLL-r) leukemias are among the leukemic subtypes with poorest survival, and treatment options have barely improved over the last decades. Despite increasing molecular understanding of the mechanisms behind these hematopoietic malignancies, this knowledge has had poor translation into the clinic. Here, we report a Drosophila melanogaster model system to explore the pathways affected in MLL-r leukemia. We show that expression of the human leukemic oncogene MLL-AF4 in the Drosophila hematopoietic system resulted in increased levels of circulating hemocytes and an enlargement of the larval hematopoietic organ, the lymph gland. Strikingly, depletion of Drosophila orthologs of known interactors of MLL-AF4, such as DOT1L, rescued the leukemic phenotype. In agreement, treatment with small-molecule inhibitors of DOT1L also prevented the MLL-AF4-induced leukemia-like phenotype. Taken together, this model provides an in vivo system to unravel the genetic interactors involved in leukemogenesis and offers a system for improved biological understanding of MLL-r leukemia.
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Affiliation(s)
- Julie A. Johannessen
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Miriam Formica
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Aina Louise C. Haukeland
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Nora Rojahn Bråthen
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Amani Al Outa
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Miriam Aarsund
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Marc Therrien
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada
- Département de pathologie et de biologie cellulaire, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Jorrit M. Enserink
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Section for Biochemistry and Molecular Biology, The Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Helene Knævelsrud
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
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3
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Agrawal-Singh S, Bagri J, Giotopoulos G, Azazi DMA, Horton SJ, Lopez CK, Anand S, Bach AS, Stedham F, Antrobus R, Houghton JW, Vassiliou GS, Sasca D, Yun H, Whetton AD, Huntly BJP. HOXA9 forms a repressive complex with nuclear matrix-associated protein SAFB to maintain acute myeloid leukemia. Blood 2023; 141:1737-1754. [PMID: 36577137 PMCID: PMC10113176 DOI: 10.1182/blood.2022016528] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 11/07/2022] [Accepted: 11/28/2022] [Indexed: 12/29/2022] Open
Abstract
HOXA9 is commonly upregulated in acute myeloid leukemia (AML), in which it confers a poor prognosis. Characterizing the protein interactome of endogenous HOXA9 in human AML, we identified a chromatin complex of HOXA9 with the nuclear matrix attachment protein SAFB. SAFB perturbation phenocopied HOXA9 knockout to decrease AML proliferation, increase differentiation and apoptosis in vitro, and prolong survival in vivo. Integrated genomic, transcriptomic, and proteomic analyses further demonstrated that the HOXA9-SAFB (H9SB)-chromatin complex associates with nucleosome remodeling and histone deacetylase (NuRD) and HP1γ to repress the expression of factors associated with differentiation and apoptosis, including NOTCH1, CEBPδ, S100A8, and CDKN1A. Chemical or genetic perturbation of NuRD and HP1γ-associated catalytic activity also triggered differentiation, apoptosis, and the induction of these tumor-suppressive genes. Importantly, this mechanism is operative in other HOXA9-dependent AML genotypes. This mechanistic insight demonstrates the active HOXA9-dependent differentiation block as a potent mechanism of disease maintenance in AML that may be amenable to therapeutic intervention by targeting the H9SB interface and/or NuRD and HP1γ activity.
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Affiliation(s)
- Shuchi Agrawal-Singh
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - Jaana Bagri
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - George Giotopoulos
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - Dhoyazan M A Azazi
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - Sarah J Horton
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - Cecile K Lopez
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - Shubha Anand
- Cancer Molecular Diagnostics Laboratory, Cancer Research UK Cambridge Centre, Cambridge, United Kingdom
| | - Anne-Sophie Bach
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - Frances Stedham
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Jack W Houghton
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - George S Vassiliou
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
- Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom
| | - Daniel Sasca
- Department of Hematology, Oncology and Pneumology, University Medical Center Mainz, Mainz, Germany
| | - Haiyang Yun
- Department of Medicine V, Hematology, Oncology and Rheumatology, University of Heidelberg, Heidelberg, Germany
| | - Anthony D Whetton
- School of Veterinary Medicine, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
| | - Brian J P Huntly
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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4
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Tang L, Peng L, Tan C, Liu H, Chen P, Wang H. Role of HOXA9 in solid tumors: mechanistic insights and therapeutic potential. Cancer Cell Int 2022; 22:349. [PMID: 36376832 PMCID: PMC9664671 DOI: 10.1186/s12935-022-02767-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 10/19/2022] [Indexed: 11/16/2022] Open
Abstract
HOXA9 functioning as a transcription factor is one of the members of HOX gene family, which governs multiple cellular activities by facilitating cellular signal transduction. In addition to be a driver in AML which has been widely studied, the role of HOXA9 in solid tumor progression has also received increasing attention in recent years, where the aberrant expression of HOXA9 is closely associated with the prognosis of patient. This review details the signaling pathways, binding partners, post-transcriptional regulation of HOXA9, and possible inhibitors of HOXA9 in solid tumors, which provides a reference basis for further study on the role of HOXA9 in solid tumors.
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5
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Lail SS, Arnold CR, de Almeida LGN, McKenna N, Chiriboga JA, Dufour A, Warren AL, Yates RM. Hox-driven conditional immortalization of myeloid and lymphoid progenitors: Uses, advantages, and future potential. Traffic 2022; 23:538-553. [PMID: 36117140 DOI: 10.1111/tra.12869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/28/2022] [Accepted: 09/12/2022] [Indexed: 01/20/2023]
Abstract
Those who study macrophage biology struggle with the decision whether to utilize primary macrophages derived directly from mice or opt for the convenience and genetic tractability of immortalized macrophage-like cell lines in in vitro studies. Particularly when it comes to studying phagocytosis and phagosomal maturation-a signature cellular process of the macrophage-many commonly used cell lines are not representative of what occurs in primary macrophages. A system developed by Mark Kamps' group, that utilizes conditionally constitutive activity of Hox transcription factors (Hoxb8 and Hoxa9) to immortalize differentiation-competent myeloid cell progenitors of mice, offers an alternative to the macrophage/macrophage-like dichotomy. In this resource, we will review the use of Hoxb8 and Hoxa9 as hematopoietic regulators to conditionally immortalize murine hematopoietic progenitor cells which retain their ability to differentiate into many functional immune cell types including macrophages, neutrophils, basophils, osteoclasts, eosinophils, dendritic cells, as well as limited potential for the generation of lymphocytes. We further demonstrate that the use of macrophages derived from Hoxb8/Hoxa9 immortalized progenitors and their similarities to bone marrow-derived macrophages. To supplement the existing data, mass spectrometry-based proteomics, flow cytometry, cytology, and in vitro phagosomal assays were conducted on macrophages derived from Hoxb8 immortalized progenitors and compared to bone marrow-derived macrophages and the macrophage-like cell line J774. We additionally propose the use of a standardized nomenclature to describe cells derived from the Hoxb8/Hoxa9 system in anticipation of their expanded use in the study of leukocyte cell biology.
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Affiliation(s)
- Shranjit S Lail
- Department of Medical Science, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Corey R Arnold
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Luiz G N de Almeida
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Neil McKenna
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jose A Chiriboga
- Department of Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Antoine Dufour
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Snyder Institute of Chronic Disease, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Amy L Warren
- Department of Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Robin Michael Yates
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.,Snyder Institute of Chronic Disease, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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6
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Franklin R, Guo Y, He S, Chen M, Ji F, Zhou X, Frankhouser D, Do BT, Chiem C, Jang M, Blanco MA, Vander Heiden MG, Rockne RC, Ninova M, Sykes DB, Hochedlinger K, Lu R, Sadreyev RI, Murn J, Volk A, Cheloufi S. Regulation of chromatin accessibility by the histone chaperone CAF-1 sustains lineage fidelity. Nat Commun 2022; 13:2350. [PMID: 35487911 PMCID: PMC9054786 DOI: 10.1038/s41467-022-29730-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/25/2022] [Indexed: 12/13/2022] Open
Abstract
Cell fate commitment is driven by dynamic changes in chromatin architecture and activity of lineage-specific transcription factors (TFs). The chromatin assembly factor-1 (CAF-1) is a histone chaperone that regulates chromatin architecture by facilitating nucleosome assembly during DNA replication. Accumulating evidence supports a substantial role of CAF-1 in cell fate maintenance, but the mechanisms by which CAF-1 restricts lineage choice remain poorly understood. Here, we investigate how CAF-1 influences chromatin dynamics and TF activity during lineage differentiation. We show that CAF-1 suppression triggers rapid differentiation of myeloid stem and progenitor cells into a mixed lineage state. We find that CAF-1 sustains lineage fidelity by controlling chromatin accessibility at specific loci, and limiting the binding of ELF1 TF at newly-accessible diverging regulatory elements. Together, our findings decipher key traits of chromatin accessibility that sustain lineage integrity and point to a powerful strategy for dissecting transcriptional circuits central to cell fate commitment.
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Affiliation(s)
- Reuben Franklin
- Department of Biochemistry, University of California, Riverside, 3401 Watkins Drive, Boyce Hall, Riverside, CA, 92521, United States
- Stem Cell Center, University of California, Riverside, 900 University Ave, Riverside, CA, 92521, United States
| | - Yiming Guo
- Department of Biochemistry, University of California, Riverside, 3401 Watkins Drive, Boyce Hall, Riverside, CA, 92521, United States
- Stem Cell Center, University of California, Riverside, 900 University Ave, Riverside, CA, 92521, United States
| | - Shiyang He
- Department of Biochemistry, University of California, Riverside, 3401 Watkins Drive, Boyce Hall, Riverside, CA, 92521, United States
| | - Meijuan Chen
- Department of Biochemistry, University of California, Riverside, 3401 Watkins Drive, Boyce Hall, Riverside, CA, 92521, United States
- Stem Cell Center, University of California, Riverside, 900 University Ave, Riverside, CA, 92521, United States
| | - Fei Ji
- Department of Molecular Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA, 02114, United States
| | - Xinyue Zhou
- Division of Hematology/Oncology, O'Neal Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - David Frankhouser
- Department of Population Sciences City of Hope National Medical Center, Duarte, CA, United States
| | - Brian T Do
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, United States
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, United States
- Harvard-MIT Division of Health Sciences and Technology, Harvard Medical School, Boston, MA, 02115, United States
| | - Carmen Chiem
- Department of Biochemistry, University of California, Riverside, 3401 Watkins Drive, Boyce Hall, Riverside, CA, 92521, United States
- Stem Cell Center, University of California, Riverside, 900 University Ave, Riverside, CA, 92521, United States
| | - Mihyun Jang
- Department of Computational and Quantitative Medicine, Division of Mathematical Oncology, City of Hope National Medical Center, Duarte, CA, United States
| | - M Andres Blanco
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Matthew G Vander Heiden
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, United States
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, United States
- Harvard-MIT Division of Health Sciences and Technology, Harvard Medical School, Boston, MA, 02115, United States
| | - Russell C Rockne
- Department of Computational and Quantitative Medicine, Division of Mathematical Oncology, City of Hope National Medical Center, Duarte, CA, United States
| | - Maria Ninova
- Department of Biochemistry, University of California, Riverside, 3401 Watkins Drive, Boyce Hall, Riverside, CA, 92521, United States
| | - David B Sykes
- Center for Regenerative Medicine, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA, 02114, United States
| | - Konrad Hochedlinger
- Department of Molecular Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA, 02114, United States
- Department of Genetics, Harvard Medical School, 25 Shattuck Street, Boston, MA, 02115, United States
- Harvard Stem Cell Institute, 1350 Massachusetts Avenue, Cambridge, MA, 02138, United States
- Cancer Center, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA, 02114, United States
| | - Rui Lu
- Division of Hematology/Oncology, O'Neal Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ruslan I Sadreyev
- Department of Molecular Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA, 02114, United States
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Jernej Murn
- Department of Biochemistry, University of California, Riverside, 3401 Watkins Drive, Boyce Hall, Riverside, CA, 92521, United States.
| | - Andrew Volk
- Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.
| | - Sihem Cheloufi
- Department of Biochemistry, University of California, Riverside, 3401 Watkins Drive, Boyce Hall, Riverside, CA, 92521, United States.
- Stem Cell Center, University of California, Riverside, 900 University Ave, Riverside, CA, 92521, United States.
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7
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Blasi F, Bruckmann C. MEIS1 in Hematopoiesis and Cancer. How MEIS1-PBX Interaction Can Be Used in Therapy. J Dev Biol 2021; 9:jdb9040044. [PMID: 34698191 PMCID: PMC8544432 DOI: 10.3390/jdb9040044] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/04/2021] [Accepted: 10/05/2021] [Indexed: 11/26/2022] Open
Abstract
Recently MEIS1 emerged as a major determinant of the MLL-r leukemic phenotype. The latest and most efficient drugs effectively decrease the levels of MEIS1 in cancer cells. Together with an overview of the latest drugs developed to target MEIS1 in MLL-r leukemia, we review, in detail, the role of MEIS1 in embryonic and adult hematopoiesis and suggest how a more profound knowledge of MEIS1 biochemistry can be used to design potent and effective drugs against MLL-r leukemia. In addition, we present data showing that the interaction between MEIS1 and PBX1 can be blocked efficiently and might represent a new avenue in anti-MLL-r and anti-leukemic therapy.
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8
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Miyamoto R, Kanai A, Okuda H, Komata Y, Takahashi S, Matsui H, Inaba T, Yokoyama A. HOXA9 promotes MYC-mediated leukemogenesis by maintaining gene expression for multiple anti-apoptotic pathways. eLife 2021; 10:e64148. [PMID: 34310280 PMCID: PMC8313233 DOI: 10.7554/elife.64148] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 07/04/2021] [Indexed: 11/13/2022] Open
Abstract
HOXA9 is often highly expressed in leukemias. However, its precise roles in leukemogenesis remain elusive. Here, we show that HOXA9 maintains gene expression for multiple anti-apoptotic pathways to promote leukemogenesis. In MLL fusion-mediated leukemia, MLL fusion directly activates the expression of MYC and HOXA9. Combined expression of MYC and HOXA9 induced leukemia, whereas single gene transduction of either did not, indicating a synergy between MYC and HOXA9. HOXA9 sustained expression of the genes implicated in the hematopoietic precursor identity when expressed in hematopoietic precursors, but did not reactivate it once silenced. Among the HOXA9 target genes, BCL2 and SOX4 synergistically induced leukemia with MYC. Not only BCL2, but also SOX4 suppressed apoptosis, indicating that multiple anti-apoptotic pathways underlie cooperative leukemogenesis by HOXA9 and MYC. These results demonstrate that HOXA9 is a crucial transcriptional maintenance factor that promotes MYC-mediated leukemogenesis, potentially explaining why HOXA9 is highly expressed in many leukemias.
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Affiliation(s)
- Ryo Miyamoto
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
| | - Akinori Kanai
- Department of Molecular Oncology and Leukemia Program Project, Research Institute for Radiation Biology and Medicine, Hiroshima UniversityHiroshimaJapan
| | - Hiroshi Okuda
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
| | - Yosuke Komata
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
| | - Satoshi Takahashi
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
- Department of Hematology and Oncology, Kyoto University Graduate School of MedicineKyotoJapan
| | - Hirotaka Matsui
- Department of Molecular Laboratory Medicine, Graduate School of Medical Sciences, Kumamoto UniversityKumamotoJapan
| | - Toshiya Inaba
- Department of Molecular Oncology and Leukemia Program Project, Research Institute for Radiation Biology and Medicine, Hiroshima UniversityHiroshimaJapan
| | - Akihiko Yokoyama
- Tsuruoka Metabolomics Laboratory, National Cancer CenterTsuruokaJapan
- Division of Hematological Malignancy, National Cancer Center Research InstituteTokyoJapan
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9
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Gİrgİn B, KaradaĞ-Alpaslan M, KocabaŞ F. Oncogenic and tumor suppressor function of MEIS and associated factors. ACTA ACUST UNITED AC 2021; 44:328-355. [PMID: 33402862 PMCID: PMC7759197 DOI: 10.3906/biy-2006-25] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 08/13/2020] [Indexed: 12/14/2022]
Abstract
MEIS proteins are historically associated with tumorigenesis, metastasis, and invasion in cancer. MEIS and associated PBX-HOX proteins may act as tumor suppressors or oncogenes in different cellular settings. Their expressions tend to be misregulated in various cancers. Bioinformatic analyses have suggested their upregulation in leukemia/lymphoma, thymoma, pancreas, glioma, and glioblastoma, and downregulation in cervical, uterine, rectum, and colon cancers. However, every cancer type includes, at least, a subtype with high MEIS expression. In addition, studies have highlighted that MEIS proteins and associated factors may function as diagnostic or therapeutic biomarkers for various diseases. Herein, MEIS proteins and associated factors in tumorigenesis are discussed with recent discoveries in addition to how they could be modulated by noncoding RNAs or newly developed small-molecule MEIS inhibitors.
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Affiliation(s)
- Birkan Gİrgİn
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, İstanbul Turkey.,Graduate School of Natural and Applied Sciences, Yeditepe University, İstanbul Turkey.,Meinox Pharma Technologies, İstanbul Turkey
| | - Medine KaradaĞ-Alpaslan
- Department of Medical Genetics, Faculty of Medicine, Ondokuz Mayıs University, Samsun Turkey
| | - Fatih KocabaŞ
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, İstanbul Turkey.,Graduate School of Natural and Applied Sciences, Yeditepe University, İstanbul Turkey.,Meinox Pharma Technologies, İstanbul Turkey
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10
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Takahashi S, Yokoyama A. The molecular functions of common and atypical MLL fusion protein complexes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194548. [PMID: 32320750 DOI: 10.1016/j.bbagrm.2020.194548] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/19/2020] [Accepted: 03/31/2020] [Indexed: 12/17/2022]
Abstract
Mixed-lineage leukemia (MLL) fuses with a variety of partners to produce a functionally altered MLL complex that is not expressed in normal cells, which transforms normal hematopoietic progenitors into leukemia cells. Because more than 80 fusion partners have been identified to date, the molecular functions of MLL fusion protein complexes appear diverse. However, over the past decade, the common functions utilized for leukemic transformation have begun to be elucidated. It appears that most (if not all) MLL fusion protein complexes utilize the AF4/ENL/P-TEFb and DOT1L complexes to some extent. Based on an understanding of the underlying molecular mechanisms, several molecular targeting drugs are being developed, opening paths to novel therapies. Here, we review the recent progress made in identifying the molecular functions of various MLL fusions and categorize the numerous fusion partners into several functionally-distinct groups to help discern commonalities and differences among various MLL fusion protein complexes.
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Affiliation(s)
- Satoshi Takahashi
- Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Japan; Department of Hematology and Oncology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Akihiko Yokoyama
- Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Japan; National Cancer Center Research Institute, Tokyo, Japan.
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11
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Hhex induces promyelocyte self-renewal and cooperates with growth factor independence to cause myeloid leukemia in mice. Blood Adv 2019; 2:347-360. [PMID: 29453249 DOI: 10.1182/bloodadvances.2017013243] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 01/24/2018] [Indexed: 12/16/2022] Open
Abstract
The hematopoietically expressed homeobox (Hhex) transcription factor is overexpressed in human myeloid leukemias. Conditional knockout models of murine acute myeloid leukemia indicate that Hhex maintains leukemia stem cell self-renewal by enabling Polycomb-mediated epigenetic repression of the Cdkn2a tumor suppressor locus, encoding p16Ink4a and p19Arf However, whether Hhex overexpression also affects hematopoietic differentiation is unknown. To study this, we retrovirally overexpressed Hhex in hematopoietic progenitors. This enabled serial replating of myeloid progenitors, leading to the rapid establishment of interleukin-3 (IL-3)-dependent promyelocytic cell lines. Use of a Hhex-ERT2 fusion protein demonstrated that continuous nuclear Hhex is required for transformation, and structure function analysis demonstrated a requirement of the DNA-binding and N-terminal-repressive domains of Hhex for promyelocytic transformation. This included the N-terminal promyelocytic leukemia protein (Pml) interaction domain, although deletion of Pml failed to prevent Hhex-induced promyelocyte transformation, implying other critical partners. Furthermore, deletion of p16Ink4a or p19Arf did not promote promyelocyte transformation, indicating that repression of distinct Hhex target genes is required for this process. Indeed, transcriptome analysis showed that Hhex overexpression resulted in repression of several myeloid developmental genes. To test the potential for Hhex overexpression to contribute to leukemic transformation, Hhex-transformed promyelocyte lines were rendered growth factor-independent using a constitutively active IL-3 receptor common β subunit (βcV449E). The resultant cell lines resulted in a rapid promyelocytic leukemia in vivo. Thus, Hhex overexpression can contribute to myeloid leukemia via multiple mechanisms including differentiation blockade and enabling epigenetic repression of the Cdkn2a locus.
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12
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Liu X, Liu X, Liu W, Luo M, Tao H, Wu D, Zhao Y, Zou L. HOXA9 transcriptionally regulates the EPHB4 receptor to modulate trophoblast migration and invasion. Placenta 2017; 51:38-48. [PMID: 28292467 DOI: 10.1016/j.placenta.2017.01.127] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/24/2017] [Accepted: 01/29/2017] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Functional placenta formation is crucially dependent on extravillous trophoblast migration and invasion. EPHB4 has been identified to play a negative but important role in regulating trophoblast biological function, whereas the upstream regulation mechanism remains unknown. As reported, there is a transcriptional stimulation of EPHB4 expression consequent to HOXA9 activation in endothelial cells (ECs). Therefore, this study is conducted to investigate the role of HOXA9 and its relationship with EPHB4 in trophoblast cells. METHOD Both mRNA and protein expression levels of HOXA9 and EPHB4 were measured in preeclamptic placenta (n = 15) and normal placenta (n = 15). Next, the expression and location of HOXA9 and EPHB4 in first-trimester villi were shown via immunohistochemistry. Trophoblast cell line HTR-8/SVneo was used to explore the effect of HOXA9 on EPHB4 expression and trophoblast bioactivity by gain- and loss-of function studies. In addition, chromatin immunoprecipitation (ChIP) and luciferase assays were conducted to clarify the regulation mechanism of HOXA9 on EPHB4 expression in HTR-8/SVneo. RESULT HOXA9 and EPHB4 expression were increased in preeclamptic placenta compared with normal placenta. HOXA9 could promote EPHB4 expression and impaired HTR-8/SVneo cells migration and invasion. ChIP and luciferase assays revealed that HOXA9 could directly bind to EPHB4 promoter and promoted its transcription. CONCLUSION HOXA9 transcriptionally regulated EPHB4 expression to modulate trophoblasts migration and invasion, which may suggest a contribution of HOXA9-EPHB4 in the poor placentation in the pathogenesis of preeclampsia.
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Affiliation(s)
- Xiaoping Liu
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoxia Liu
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Weifang Liu
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Minglian Luo
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hui Tao
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Di Wu
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yin Zhao
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Li Zou
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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13
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Yokoyama A. Transcriptional activation by MLL fusion proteins in leukemogenesis. Exp Hematol 2016; 46:21-30. [PMID: 27865805 DOI: 10.1016/j.exphem.2016.10.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 10/14/2016] [Accepted: 10/29/2016] [Indexed: 12/16/2022]
Abstract
Chromosomal translocations involving the mixed lineage leukemia (MLL) gene cause aggressive leukemia. Fusion proteins of MLL and a component of the AF4 family/ENL family/P-TEFb complex (AEP) are responsible for two-thirds of MLL-associated leukemia cases. MLL-AEP fusion proteins trigger aberrant self-renewal of hematopoietic progenitors by constitutively activating self-renewal-related genes. MLL-AEP fusion proteins activate transcription initiation by loading the TATA-binding protein (TBP) to the TATA element via selectivity factor 1. Although AEP retains transcription elongation and mediator recruiting activities, the rate-limiting step activated by MLL-AEP fusion proteins appears to be the TBP-loading step. This is contrary to prevailing views, in which the recruitment of transcription elongation activities are emphasized. Here, I review recent advances towards elucidating the mechanisms underlying gene activation by MLL-AEP fusion proteins in leukemogenesis.
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Affiliation(s)
- Akihiko Yokoyama
- Department of Hematology and Oncology, Kyoto University Graduate School of Medicine, Kyoto, Japan; Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo, Japan.
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14
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Controlled stem cell amplification by HOXB4 depends on its unique proline-rich region near the N terminus. Blood 2016; 129:319-323. [PMID: 27827825 DOI: 10.1182/blood-2016-04-706978] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 10/29/2016] [Indexed: 01/09/2023] Open
Abstract
There is high interest in understanding the mechanisms that drive self-renewal of stem cells. HOXB4 is one of the few transcription factors that can amplify long-term repopulating hematopoietic stem cells in a controlled way. Here we show in mice that this characteristic of HOXB4 depends on a proline-rich sequence near the N terminus, which is unique among HOX genes and highly conserved in higher mammals. Deletion of this domain substantially enhanced the oncogenicity of HOXB4, inducing acute leukemia in mice. Conversely, insertion of the domain into Hoxa9 impaired leukemogenicity of this homeobox gene. These results indicate that proline-rich stretches attenuate the potential of stem cell active homeobox genes to acquire oncogenic properties.
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15
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Okuda H, Takahashi S, Takaori-Kondo A, Yokoyama A. TBP loading by AF4 through SL1 is the major rate-limiting step in MLL fusion-dependent transcription. Cell Cycle 2016; 15:2712-22. [PMID: 27564129 DOI: 10.1080/15384101.2016.1222337] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Gene rearrangement of the mixed lineage leukemia (MLL) gene causes leukemia by inducing the constitutive expression of a gene subset normally expressed only in the immature haematopoietic progenitor cells. MLL gene rearrangements often generate fusion products of MLL and a component of the AF4 family/ENL family/P-TEFb (AEP) complex. MLL-AEP fusion proteins have the potential of constitutively recruiting the P-TEFb elongation complex. Thus, it is hypothesized that relieving the promoter proximal pausing of RNA polymerase II is the rate-limiting step of MLL fusion-dependent transcription. AEP also has the potential to recruit the mediator complex via MED26. We recently showed that AEP activates transcription initiation by facilitating TBP loading to the TATA element through the SL1 complex. In the present study, we show that the key activity responsible for the oncogenic property of MLL-AEP fusion proteins is the TBP loading activity, and not the mediator recruitment or transcriptional elongation activities. Thus, we propose that TBP loading by AF4 through SL1 is the major rate-limiting step in MLL fusion-dependent transcription.
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Affiliation(s)
- Hiroshi Okuda
- a Laboratory for Malignancy Control Research , Kyoto University Graduate School of Medicine , Kyoto , Japan
| | - Satoshi Takahashi
- b Department of Hematology and Oncology , Graduate School of Medicine , Kyoto , Japan
| | - Akifumi Takaori-Kondo
- b Department of Hematology and Oncology , Graduate School of Medicine , Kyoto , Japan
| | - Akihiko Yokoyama
- a Laboratory for Malignancy Control Research , Kyoto University Graduate School of Medicine , Kyoto , Japan.,b Department of Hematology and Oncology , Graduate School of Medicine , Kyoto , Japan
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16
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Thorne RMW, Milne TA. Dangerous liaisons: cooperation between Pbx3, Meis1 and Hoxa9 in leukemia. Haematologica 2016; 100:850-3. [PMID: 26130510 DOI: 10.3324/haematol.2015.129932] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Ross M W Thorne
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, UK
| | - Thomas A Milne
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, UK
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17
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Lentiviral vector system for coordinated constitutive and drug controlled tetracycline-regulated gene co-expression. Biomaterials 2015; 63:189-201. [DOI: 10.1016/j.biomaterials.2015.06.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/10/2015] [Accepted: 06/12/2015] [Indexed: 12/15/2022]
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18
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Ogawara Y, Katsumoto T, Aikawa Y, Shima Y, Kagiyama Y, Soga T, Matsunaga H, Seki T, Araki K, Kitabayashi I. IDH2 and NPM1 Mutations Cooperate to Activate Hoxa9/Meis1 and Hypoxia Pathways in Acute Myeloid Leukemia. Cancer Res 2015; 75:2005-16. [PMID: 25795706 DOI: 10.1158/0008-5472.can-14-2200] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 03/03/2015] [Indexed: 11/16/2022]
Abstract
IDH1 and IDH2 mutations occur frequently in acute myeloid leukemia (AML) and other cancers. The mutant isocitrate dehydrogenase (IDH) enzymes convert α-ketoglutarate (α-KG) to the oncometabolite 2-hydroxyglutarate (2-HG), which dysregulates a set of α-KG-dependent dioxygenases. To determine whether mutant IDH enzymes are valid targets for cancer therapy, we created a mouse model of AML in which mice were transplanted with nucleophosmin1 (NPM)(+/-) hematopoietic stem/progenitor cells cotransduced with four mutant genes (NPMc, IDH2/R140Q, DNMT3A/R882H, and FLT3/ITD), which often occur simultaneously in human AML patients. Conditional deletion of IDH2/R140Q blocked 2-HG production and maintenance of leukemia stem cells, resulting in survival of the AML mice. IDH2/R140Q was necessary for the engraftment or survival of NPMc(+) cells in vivo. Gene expression analysis indicated that NPMc increased expression of Hoxa9. IDH2/R140Q also increased the level of Meis1 and activated the hypoxia pathway in AML cells. IDH2/R140Q decreased the 5hmC modification and expression of some differentiation-inducing genes (Ebf1 and Spib). Taken together, our results indicated that IDH2 mutation is critical for the development and maintenance of AML stem-like cells, and they provided a preclinical justification for targeting mutant IDH enzymes as a strategy for anticancer therapy.
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Affiliation(s)
- Yoko Ogawara
- Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo, Japan
| | - Takuo Katsumoto
- Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo, Japan
| | - Yukiko Aikawa
- Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo, Japan
| | - Yutaka Shima
- Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo, Japan
| | - Yuki Kagiyama
- Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo, Japan
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan
| | | | - Takahiko Seki
- R&D Division, Daiichi Sankyo Co., Ltd., Tokyo, Japan
| | - Kazushi Araki
- R&D Division, Daiichi Sankyo Co., Ltd., Tokyo, Japan
| | - Issay Kitabayashi
- Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo, Japan.
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19
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Kovacevic-Grujicic N, Mojsin M, Popovic J, Petrovic I, Topalovic V, Stevanovic M. Cyclic AMP response element binding (CREB) protein acts as a positive regulator of SOX3 gene expression in NT2/D1 cells. BMB Rep 2015; 47:197-202. [PMID: 24257117 PMCID: PMC4163894 DOI: 10.5483/bmbrep.2014.47.4.084] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 04/29/2013] [Accepted: 06/20/2014] [Indexed: 11/20/2022] Open
Abstract
SOX3 is one of the earliest neural markers in vertebrates, playing the role in specifying neuronal fate. In this study we have established first functional link between CREB and human SOX3 gene which both have important roles in the nervous system throughout development and in the adulthood. Here we demonstrate both in vitro and in vivo that CREB binds to CRE half-site located -195 to -191 within the human SOX3 promoter. Overexpression studies with CREB or its dominant-negative inhibitor A-CREB indicate that this transcription factor acts as a positive regulator of basal SOX3 gene expression in NT2/D1 cells. This is further confirmed by mutational analysis where mutation of CREB binding site results in reduction of SOX3 promoter activity. Our results point at CREB as a positive regulator of SOX3 gene transcription in NT2/D1 cells, while its contribution to RA induction of SOX3 promoter is not prominent. [BMB Reports 2014; 47(4): 197-202]
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Affiliation(s)
- Natasa Kovacevic-Grujicic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, PO BOX 23, 11010 Belgrade, Serbia
| | - Marija Mojsin
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, PO BOX 23, 11010 Belgrade, Serbia
| | - Jelena Popovic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, PO BOX 23, 11010 Belgrade, Serbia
| | - Isidora Petrovic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, PO BOX 23, 11010 Belgrade, Serbia
| | - Vladanka Topalovic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, PO BOX 23, 11010 Belgrade, Serbia
| | - Milena Stevanovic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, PO BOX 23, 11010 Belgrade, Serbia
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20
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Li W, Huang K, Guo H, Cui G, Zhao S. Inhibition of non-small-cell lung cancer cell proliferation by Pbx1. Chin J Cancer Res 2014; 26:573-8. [PMID: 25400423 DOI: 10.3978/j.issn.1000-9604.2014.08.21] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/15/2014] [Indexed: 11/14/2022] Open
Abstract
Lung cancer is one of the most deadly human cancers and continues to be a major unsolved health problem worldwide. Here, we evaluate the function of Pbx1 in the proliferation of non-small-cell lung cancer (NSCLC). In contrast with its known proliferative function, we found that Pbx1 inhibits the proliferation of lung cancer cells. In particular, Pbx1-specific RNA interference resulted in increased proliferation in lung cancer cells. In addition, histone H3 phosphorylation was also increased following inhibition of Pbx1 expression. In contrast, Pbx1 overexpression repressed the proliferation of lung cancer cells and inhibited DNA synthesis. Collectively, our data indicate that Pbx1 inhibits proliferation in lung cancer cells, suggesting a complex role for Pbx1 in modulating the proliferation of cancer cells and making this protein a potential new target for lung cancer therapy.
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Affiliation(s)
- Weihao Li
- 1 Department of Thoracic Surgery, 2 Department of Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
| | - Kai Huang
- 1 Department of Thoracic Surgery, 2 Department of Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
| | - Haizhou Guo
- 1 Department of Thoracic Surgery, 2 Department of Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
| | - Guanghui Cui
- 1 Department of Thoracic Surgery, 2 Department of Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
| | - Song Zhao
- 1 Department of Thoracic Surgery, 2 Department of Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
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21
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Brumatti G, Salmanidis M, Kok CH, Bilardi RA, Sandow JJ, Silke N, Mason K, Visser J, Jabbour AM, Glaser SP, Okamoto T, Bouillet P, D'Andrea RJ, Ekert PG. HoxA9 regulated Bcl-2 expression mediates survival of myeloid progenitors and the severity of HoxA9-dependent leukemia. Oncotarget 2014; 4:1933-47. [PMID: 24177192 PMCID: PMC3875760 DOI: 10.18632/oncotarget.1306] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Deregulated expression of Hox genes such as HoxA9 is associated with development of myeloproliferative disorders and leukemia and indicates a poor prognosis. To investigate the molecular mechanisms by which HoxA9 promotes immortalization of hematopoietic cells, we generated growth factor dependent myeloid cells in which HoxA9 expression is regulated by administration of 4-hydroxy-tamoxifen. Maintenance of HoxA9 overexpression is required for continued cell survival and proliferation, even in the presence of growth factors. We show for the first time that maintenance of Bcl-2 expression is critical for HoxA9-dependent immortalization and influences the latency of HoxA9-dependent leukemia. Hematopoietic cells lacking Bcl-2 were not immortalized by HoxA9 in vitro. Furthermore, deletion of Bcl-2 delayed the onset and reduced the severity of HoxA9/Meis1 and MLL-AF9 leukemias. This is the first description of a molecular link between HoxA9 and the regulation of Bcl-2 family members in acute myeloid leukemia.
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Affiliation(s)
- Gabriela Brumatti
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Australia
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22
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The leukemogenicity of Hoxa9 depends on alternative splicing. Leukemia 2014; 28:1838-43. [PMID: 24535405 DOI: 10.1038/leu.2014.74] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 02/03/2014] [Accepted: 02/07/2014] [Indexed: 01/22/2023]
Abstract
Although the transforming potential of Hox genes is known for a long time, it is not precisely understood to which extent splicing is important for the leukemogenicity of this gene family. To test this for Hoxa9, we compared the leukemogenic potential of the wild-type Hoxa9, which undergoes natural splicing, with a full-length Hoxa9 construct, which was engineered to prevent natural splicing (Hoxa9FLim). Inability to undergo splicing significantly reduced in vivo leukemogenicity compared to Hoxa9-wild-typed. Importantly, Hoxa9FLim could compensate for the reduced oncogenicity by collaborating with the natural splice variant Hoxa9T, as co-expression of Hoxa9T and Hoxa9FLim induced acute myeloid leukemia (AML) after a comparable latency time as wild-type Hoxa9. Hoxa9T on its own induced AML after a similar latency as Hoxa9FLim, despite its inability to bind DNA. These data assign splicing a central task in Hox gene mediated leukemogenesis and suggest an important role of homeodomain-less splice variants in hematological neoplasms.
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23
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Ding X, Yang Z, Zhou F, Wang F, Li X, Chen C, Li X, Hu X, Xiang S, Zhang J. Transcription factor AP-2α regulates acute myeloid leukemia cell proliferation by influencing Hoxa gene expression. Int J Biochem Cell Biol 2013; 45:1647-56. [DOI: 10.1016/j.biocel.2013.04.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 04/26/2013] [Accepted: 04/29/2013] [Indexed: 01/28/2023]
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24
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Casaca A, Santos AC, Mallo M. Controlling Hox gene expression and activity to build the vertebrate axial skeleton. Dev Dyn 2013; 243:24-36. [DOI: 10.1002/dvdy.24007] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/18/2013] [Accepted: 06/21/2013] [Indexed: 11/10/2022] Open
Affiliation(s)
- Ana Casaca
- Instituto Gulbenkian de Ciência; Oeiras Portugal
| | | | - Moisés Mallo
- Instituto Gulbenkian de Ciência; Oeiras Portugal
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25
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Beachy SH, Onozawa M, Silverman D, Chung YJ, Rivera MM, Aplan PD. Isolated Hoxa9 overexpression predisposes to the development of lymphoid but not myeloid leukemia. Exp Hematol 2013; 41:518-529.e5. [PMID: 23435313 DOI: 10.1016/j.exphem.2013.02.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 02/11/2013] [Accepted: 02/13/2013] [Indexed: 01/07/2023]
Abstract
Hoxa9 is expressed in hematopoietic stem and progenitor cells, although this expression is usually diminished as these cells undergo differentiation. In addition, aberrant expression of Hoxa9 is strongly associated with both T cell and myeloid leukemia in mice and humans. Despite this strong association, enforced expression of Hoxa9 in murine bone marrow or thymus has only shown a modest ability to transform cells. To investigate this question, we used Vav regulatory elements to generate a transgenic mouse that targets Hoxa9 overexpression to all hematopoietic tissues. High-level expression of the Hoxa9 transgene in the hematopoietic compartment was associated with embryonic lethality, as no pups from founders that expressed high levels of the transgene were born live. However, offspring of an additional founder line, which expressed lower levels of Hoxa9, developed a precursor T cell lymphoblastic leukemia/lymphoma, accompanied by spontaneous Notch1 mutations. In contrast to most murine models of leukemia associated with Hoxa9 overexpression, the Vav-Hoxa9 mice did not overexpress other Hoxa cluster genes, mir196b (a microRNA that is embedded in the Hoxa locus), Meis1, or Pbx3. The Hoxa9 transgenic mouse reported in this study provides a suitable system for the study of Hoxa9 collaborators that drive myeloid and lymphoid malignant transformation.
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Affiliation(s)
- Sarah H Beachy
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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26
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Abstract
HOX proteins are widely involved in hematopoietic development. These transcription factors combine a conserved DNA-binding homeobox with a divergent N-terminus that mediates interaction with variable cofactors. The resulting combinatorial diversity is thought to be responsible for mammalian HOX specificity. Contrasting this proposed mechanism for normal HOX function, here we demonstrate that, in the context of hematopoietic immortalization and leukemogenesis, individual HOX properties are governed almost exclusively by the homeodomain. Swap experiments between HOXA1 and HOXA9, 2 members of nonrelated paralog groups, revealed that gene expression patterns of HOX transformed cells in vitro are determined by the nature of the homeodomain. Similar results were seen in vivo during HOX-mediated leukemogenesis. An exchange of the homeodomains was sufficient to convert the slow, low-penetrance phenotype of HOXA1-induced leukemia to the aggressive fast-acting disease elicited by HOXA9 and vice versa. Mutation and deletion studies identified several subregions within the DNA binding domain responsible for paralog specificity. Previously defined binding sites for PBX cofactors within the exchangeable, nonhomeobox segment were dispensable for in vitro oncogenic HOX activity but affected in vivo disease development. The transcriptional activator domain shared by HOXA1 and HOXA9 at the very N-terminus proved essential for all transformation.
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27
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miRNA let-7c promotes granulocytic differentiation in acute myeloid leukemia. Oncogene 2012; 32:3648-54. [PMID: 22964640 DOI: 10.1038/onc.2012.398] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 07/17/2012] [Accepted: 07/20/2012] [Indexed: 02/08/2023]
Abstract
MicroRNAs (miRNAs), small non-coding RNAs that regulate gene expression post-transcriptionally, are involved in many complex cellular processes. Several miRNAs are differentially expressed in hematopoietic tissues and play important roles in normal differentiation, but, when aberrantly regulated, contribute to the abnormal proliferation and differentiation of leukemic cells. Recently, we reported that a small subset of miRNAs is differentially expressed in acute promyelocytic leukemia (APL) blasts and is modulated by treatment with all-trans-retinoic acid (ATRA). In particular, PML/RARα-positive blasts from APL patients display lower levels of miRNA let-7c, a member of the let-7 family, than normal promyelocytes and its expression increases after ATRA treatment. In this study, we investigated the effects of let-7c in acute myeloid leukemia (AML) cells. We found that ectopic expression of let-7c promotes granulocytic differentiation of AML cell lines and primary blasts. Moreover, we identified PBX2, a well-known homeodomain protein whose aberrant expression enhances HoxA9-dependent leukemogenesis, as a novel let-7c target that may contribute to the AML phenotype. Together, these studies raise the possibility that perturbation of the let-7c-PBX2 pathway may have a therapeutic value in AML.
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28
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Lelli KM, Slattery M, Mann RS. Disentangling the many layers of eukaryotic transcriptional regulation. Annu Rev Genet 2012; 46:43-68. [PMID: 22934649 DOI: 10.1146/annurev-genet-110711-155437] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Regulation of gene expression in eukaryotes is an extremely complex process. In this review, we break down several critical steps, emphasizing new data and techniques that have expanded current gene regulatory models. We begin at the level of DNA sequence where cis-regulatory modules (CRMs) provide important regulatory information in the form of transcription factor (TF) binding sites. In this respect, CRMs function as instructional platforms for the assembly of gene regulatory complexes. We discuss multiple mechanisms controlling complex assembly, including cooperative DNA binding, combinatorial codes, and CRM architecture. The second section of this review places CRM assembly in the context of nucleosomes and condensed chromatin. We discuss how DNA accessibility and histone modifications contribute to TF function. Lastly, new advances in chromosomal mapping techniques have provided increased understanding of intra- and interchromosomal interactions. We discuss how these topological maps influence gene regulatory models.
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Affiliation(s)
- Katherine M Lelli
- Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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29
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Lee JW, Kim HS, Hwang J, Kim YH, Lim GY, Sohn WJ, Yoon SR, Kim JY, Park TS, Oh SH, Park KM, Choi SU, Ryoo ZY, Lee S. Regulation of HOXA9 activity by predominant expression of DACH1 against C/EBPα and GATA-1 in myeloid leukemia with MLL-AF9. Biochem Biophys Res Commun 2012; 426:299-305. [PMID: 22902925 DOI: 10.1016/j.bbrc.2012.08.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 08/10/2012] [Indexed: 02/03/2023]
Abstract
Although MLL-AF9 caused by the chromosomal translocation t(9;11) has a critical role in acute myeloid leukemia, the molecular pathogenesis is poorly understood. Here, we identified that the cell fate determination factor DACH1 is directly up-regulated by MLL-AF9. Recently we showed that the forced expression of DACH1 in myeloid cells induced p27(Kip1) and repressed p21(Cip1), which is a pivotal characteristic of the myeloid progenitor. Consistent with our previous study, ectopic expression of DACH1 contributed to the maintenance of colonogenic activity and blocked the differentiation of myeloid progenitors. Moreover, we here identified an endogenous HOXA9-DACH1 complex mediated by the carboxyl terminus of DACH1 in t(9;11) leukemia cells. qRT-PCR revealed that DACH1 has a stronger transcription-promoting activity with HOXA9 than does PBX2 with HOXA9. Furthermore, C/EBPα and GATA-1 can directly bind to the promoter of DACH1 and act as a transcriptional suppressor. Expression of DACH1 is down-regulated during myeloid differentiation and shows an inverse pattern compared to C/EBPα and GATA-1 expression. However, ectopic expression of C/EBPα and/or GATA-1 could not abrogate the over-expression of DACH1 induced by MLL-AF9. Therefore, we postulate that the inability of C/EBPα and GATA-1 to down-regulate DACH1 expression induced by MLL-AF9 during myeloid differentiation may contribute to t(9;11) leukemogenesis.
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Affiliation(s)
- Jae-Woong Lee
- School of Life Science and Biotechnology, Kyungpook National University, Daegu 702-701, Republic of Korea
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Distinct regulation of c-myb gene expression by HoxA9, Meis1 and Pbx proteins in normal hematopoietic progenitors and transformed myeloid cells. Blood Cancer J 2012; 2:e76. [PMID: 22829978 PMCID: PMC3389162 DOI: 10.1038/bcj.2012.20] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 05/03/2012] [Accepted: 05/07/2012] [Indexed: 12/11/2022] Open
Abstract
The proto-oncogenic protein c-Myb is an essential regulator of hematopoiesis and is frequently deregulated in hematological diseases such as lymphoma and leukemia. To gain insight into the mechanisms underlying the aberrant expression of c-Myb in myeloid leukemia, we analyzed and compared c-myb gene transcriptional regulation using two cell lines modeling normal hematopoietic progenitor cells (HPCs) and transformed myelomonocytic blasts. We report that the transcription factors HoxA9, Meis1, Pbx1 and Pbx2 bind in vivo to the c-myb locus and maintain its expression through different mechanisms in HPCs and leukemic cells. Our analysis also points to a critical role for Pbx2 in deregulating c-myb expression in murine myeloid cells cotransformed by the cooperative activity of HoxA9 and Meis1. This effect is associated with an intronic positioning of epigenetic marks and RNA polymerase II binding in the orthologous region of a previously described alternative promoter for c-myb. Taken together, our results could provide a first hint to explain the abnormal expression of c-myb in leukemic cells.
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31
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Breitinger C, Maethner E, Garcia-Cuellar MP, Schambony A, Fischer KD, Schilling K, Slany RK. HOX genes regulate Rac1 activity in hematopoietic cells through control of Vav2 expression. Leukemia 2012; 27:236-8. [PMID: 22713647 DOI: 10.1038/leu.2012.166] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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32
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He M, Chen P, Arnovitz S, Li Y, Huang H, Neilly MB, Wei M, Rowley JD, Chen J, Li Z. Two isoforms of HOXA9 function differently but work synergistically in human MLL-rearranged leukemia. Blood Cells Mol Dis 2012; 49:102-6. [PMID: 22633751 DOI: 10.1016/j.bcmd.2012.05.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 05/01/2012] [Indexed: 02/07/2023]
Abstract
HOXA9 plays a critical role in both normal hematopoiesis and leukemogenesis, particularly in the development and maintenance of mixed lineage leukemia (MLL)-rearranged leukemia. Through reverse transcription-polymerase chain reaction (RT-PCR) analysis of HOXA9 transcripts in human leukemia and normal bone marrow samples, we identified a truncated isoform of HOXA9, namely HOXA9T, and found that both HOXA9T and canonical HOXA9 were highly expressed in leukemia cell lines bearing MLL rearrangements, relative to human normal bone marrow cells or other subtypes of leukemia cells. A frameshift in HOXA9T in exon I causes a premature stop codon upstream of the PBX-binding domain and the homeodomain, which leads to the generation of a non-homeodomain-containing protein. Unlike the canonical HOXA9, HOXA9T alone cannot transform normal bone marrow progenitor cells. Moreover, HOXA9T cannot cooperate with MEIS1 to transform cells, despite the presence of a MEIS1-binding domain. Remarkably, although the truncated isoforms of many proteins function as dominant-negative competitors or inhibitors of their full-length counterparts, this is not the case for HOXA9T; instead, HOXA9T synergized with HOXA9 in transforming mouse normal bone marrow progenitor cells through promoting self-renewal and proliferation of the cells. Collectively, our data indicate that both truncated and full-length forms of HOXA9 are highly expressed in human MLL-rearranged leukemia, and the truncated isoform of HOXA9 might also play an oncogenic role by cooperating with canonical HOXA9 in cell transformation and leukemogenesis.
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Affiliation(s)
- Miao He
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago, IL, USA
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33
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Kataoka K, Kurokawa M. Ecotropic viral integration site 1, stem cell self-renewal and leukemogenesis. Cancer Sci 2012; 103:1371-7. [PMID: 22494115 DOI: 10.1111/j.1349-7006.2012.02303.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/02/2012] [Accepted: 04/08/2012] [Indexed: 12/27/2022] Open
Abstract
It has become evident that acute myeloid leukemia (AML) is organized as a cellular hierarchy initiated and maintained by a subset of self-renewing leukemia stem cells. Recent gene expression profile analysis of human leukemia stem cells and hematopoietic stem cell (HSC) populations identified a key transcriptional program shared by leukemia stem cells and HSC, which is associated with adverse outcomes in AML patients. One molecule that has been established as a pivotal regulator in fine-tuning of stem cell properties as well as a potent oncogenic determinant is ecotropic viral integration site 1 (EVI1). EVI1 is a transcription factor that has stem cell-specific expression pattern and is essential for the regulation of HSC self-renewal. This gene is notorious for its involvement in AML, as its activation confers extremely poor prognosis in patients with AML. Molecular analysis has identified a variety of gene products that are involved in HSC regulation as downstream targets or interacting proteins of EVI1. Thus, exploration of the molecular pathogenesis underlying EVI1-related leukemogenesis provides insight into how shared stemness transcriptional programs contribute to leukemia progression and therapeutic resistance in AML. Here, we review the current knowledge regarding the role of EVI1 in HSC self-renewal and leukemogenesis and highlight the relationship between stem cell self-renewal properties and adverse outcome in myeloid malignancies.
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Affiliation(s)
- Keisuke Kataoka
- Department of Hematology and Oncology, University of Tokyo, Tokyo, Japan
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Yokoyama A, Ficara F, Murphy MJ, Meisel C, Naresh A, Kitabayashi I, Cleary ML. Proteolytically cleaved MLL subunits are susceptible to distinct degradation pathways. J Cell Sci 2011; 124:2208-19. [PMID: 21670200 DOI: 10.1242/jcs.080523] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The mixed lineage leukemia (MLL) proto-oncogenic protein is a histone-lysine N-methyltransferase that is produced by proteolytic cleavage and self-association of the respective functionally distinct subunits (MLL(N) and MLL(C)) to form a holocomplex involved in epigenetic transcriptional regulation. On the basis of studies in Drosophila it has been suggested that the separated subunits might also have distinct functions. In this study, we used a genetically engineered mouse line that lacked MLL(C) to show that the MLL(N)-MLL(C) holocomplex is responsible for MLL functions in various developmental processes. The stability of MLL(N) is dependent on its intramolecular interaction with MLL(C), which is mediated through the first and fourth plant homeodomain (PHD) fingers (PHD1 and PHD4) and the phenylalanine/tyrosine-rich (FYRN) domain of MLL(N). Free MLL(N) is destroyed by a mechanism that targets the FYRN domain, whereas free MLL(C) is exported to the cytoplasm and degraded by the proteasome. PHD1 is encoded by an alternatively spliced exon that is occasionally deleted in T-cell leukemia, and its absence produces an MLL mutant protein that is deficient for holocomplex formation. Therefore, this should be a loss-of-function mutant allele, suggesting that the known tumor suppression role of MLL may also apply to the T-cell lineage. Our data demonstrate that the dissociated MLL subunits are subjected to distinct degradation pathways and thus not likely to have separate functions unless the degradation mechanisms are inhibited.
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Affiliation(s)
- Akihiko Yokoyama
- Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo 104-0045, Japan.
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35
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Abstract
The clustered homeobox proteins play crucial roles in development, hematopoiesis, and leukemia, yet the targets they regulate and their mechanisms of action are poorly understood. Here, we identified the binding sites for Hoxa9 and the Hox cofactor Meis1 on a genome-wide level and profiled their associated epigenetic modifications and transcriptional targets. Hoxa9 and the Hox cofactor Meis1 cobind at hundreds of highly evolutionarily conserved sites, most of which are distant from transcription start sites. These sites show high levels of histone H3K4 monomethylation and CBP/P300 binding characteristic of enhancers. Furthermore, a subset of these sites shows enhancer activity in transient transfection assays. Many Hoxa9 and Meis1 binding sites are also bound by PU.1 and other lineage-restricted transcription factors previously implicated in establishment of myeloid enhancers. Conditional Hoxa9 activation is associated with CBP/P300 recruitment, histone acetylation, and transcriptional activation of a network of proto-oncogenes, including Erg, Flt3, Lmo2, Myb, and Sox4. Collectively, this work suggests that Hoxa9 regulates transcription by interacting with enhancers of genes important for hematopoiesis and leukemia.
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36
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Abstract
Structural chromosomal rearrangements of the Nucleoporin 98 gene (NUP98), primarily balanced translocations and inversions, are associated with a wide array of hematopoietic malignancies. NUP98 is known to be fused to at least 28 different partner genes in patients with hematopoietic malignancies, including acute myeloid leukemia, chronic myeloid leukemia in blast crisis, myelodysplastic syndrome, acute lymphoblastic leukemia, and bilineage/biphenotypic leukemia. NUP98 gene fusions typically encode a fusion protein that retains the amino terminus of NUP98; in this context, it is important to note that several recent studies have demonstrated that the amino-terminal portion of NUP98 exhibits transcription activation potential. Approximately half of the NUP98 fusion partners encode homeodomain proteins, and at least 5 NUP98 fusions involve known histone-modifying genes. Several of the NUP98 fusions, including NUP98-homeobox (HOX)A9, NUP98-HOXD13, and NUP98-JARID1A, have been used to generate animal models of both lymphoid and myeloid malignancy; these models typically up-regulate HOXA cluster genes, including HOXA5, HOXA7, HOXA9, and HOXA10. In addition, several of the NUP98 fusion proteins have been shown to inhibit differentiation of hematopoietic precursors and to increase self-renewal of hematopoietic stem or progenitor cells, providing a potential mechanism for malignant transformation.
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Bjerke GA, Hyman-Walsh C, Wotton D. Cooperative transcriptional activation by Klf4, Meis2, and Pbx1. Mol Cell Biol 2011; 31:3723-33. [PMID: 21746878 PMCID: PMC3165729 DOI: 10.1128/mcb.01456-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 06/30/2011] [Indexed: 11/20/2022] Open
Abstract
The Kruppel-like factor Klf4 is implicated in tumorigenesis and maintaining stem cell pluripotency, and Klf4 can both activate and repress gene expression. We show that the Pbx1 and Meis2 homeodomain proteins interact with Klf4 and can be recruited to DNA elements comprising a Klf4 site or GC box, with adjacent Meis and Pbx sites. Meis2d and Pbx1a activate expression of p15(Ink4a) and E-cadherin, dependent on the Meis2d transcriptional activation domain. In HepG2 cells, reducing expression of endogenous Meis2 or Pbx1 decreases p15 gene expression and increases the number of cells entering S phase. Although DNA binding by all three proteins contributes to full cooperative activation, the sequence requirements for binding by Meis2 and Pbx1 are variable. In the E-cadherin promoter, a Pbx-like site is required for full activation, whereas in the p15 promoter, the Klf4 site appears to play the major role. Through a bioinformatics search we identified additional genes with conserved binding sites for Klf4, Meis2, and Pbx1 and show that at least some of these genes can be activated cooperatively by Klf4 and Meis2/Pbx1. We suggest a model in which genes with Klf4 sites can be cooperatively activated by Meis2/Pbx1 and Klf4, dependent primarily on recruitment by Klf4. This provides a mechanism to modulate transcriptional regulation by the multifunctional Klf4 transcription factor.
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Affiliation(s)
- Glen A. Bjerke
- Department of Biochemistry and Molecular Genetics and Center for Cell Signaling, University of Virginia, Charlottesville, Virginia
| | - Cathy Hyman-Walsh
- Department of Biochemistry and Molecular Genetics and Center for Cell Signaling, University of Virginia, Charlottesville, Virginia
| | - David Wotton
- Department of Biochemistry and Molecular Genetics and Center for Cell Signaling, University of Virginia, Charlottesville, Virginia
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Abstract
Cancer is a complex disease in which cells have circumvented normal restraints on tissue growth and have acquired complex abnormalities in their genomes, posing a considerable challenge to identifying the pathways and mechanisms that drive fundamental aspects of the malignant phenotype. Genetic analyses of the normal development of the nematode Caenorhabditis elegans have revealed evolutionarily conserved mechanisms through which individual cells establish their fates, and how they make and execute the decision to survive or undergo programmed cell death. The pathways identified through these studies have mammalian counterparts that are co-opted by malignant cells. Effective cancer drugs now target some of these pathways, and more are likely to be discovered.
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Affiliation(s)
- Malia B Potts
- Departments of Pediatrics and Molecular Biology, University of Texas Southwestern Medical Center at Dallas, 75390-9148, USA
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Evi-1 is a transcriptional target of mixed-lineage leukemia oncoproteins in hematopoietic stem cells. Blood 2010; 117:6304-14. [PMID: 21190993 DOI: 10.1182/blood-2009-07-234310] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Ecotropic viral integration site-1 (Evi-1) is a nuclear transcription factor that plays an essential role in the regulation of hematopoietic stem cells. Aberrant expression of Evi-1 has been reported in up to 10% of patients with acute myeloid leukemia and is a diagnostic marker that predicts a poor outcome. Although chromosomal rearrangement involving the Evi-1 gene is one of the major causes of Evi-1 activation, overexpression of Evi-1 is detected in a subgroup of acute myeloid leukemia patients without any chromosomal abnormalities, which indicates the presence of other mechanisms for Evi-1 activation. In this study, we found that Evi-1 is frequently up-regulated in bone marrow cells transformed by the mixed-lineage leukemia (MLL) chimeric genes MLL-ENL or MLL-AF9. Analysis of the Evi-1 gene promoter region revealed that MLL-ENL activates transcription of Evi-1. MLL-ENL-mediated up-regulation of Evi-1 occurs exclusively in the undifferentiated hematopoietic population, in which Evi-1 particularly contributes to the propagation of MLL-ENL-immortalized cells. Furthermore, gene-expression analysis of human acute myeloid leukemia cases demonstrated the stem cell-like gene-expression signature of MLL-rearranged leukemia with high levels of Evi-1. Our findings indicate that Evi-1 is one of the targets of MLL oncoproteins and is selectively activated in hematopoietic stem cell-derived MLL leukemic cells.
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Abstract
OBJECTIVE Homeobox genes of the Hox class are required for proper patterning of skeletal elements and play a role in cartilage differentiation. In transgenic mice with overexpression of Hoxc8 and Hoxd4 during cartilage development, the authors observed severe defects, namely, physical instability of cartilage, accumulation of immature chondrocytes, and decreased maturation to hypertrophy. To define the molecular basis underlying these defects, the authors performed gene expression profiling using the Affymetrix microarray platform. RESULTS Primary chondrocytes were isolated from Hoxc8- and Hoxd4-transgenic mouse embryo rib cartilage at 18.5 days of gestation. In both cases, differentially expressed genes were identified that have a role in cell proliferation and cell cycle regulation. A comparison between the controls for both experimental groups did not reveal significant differences, as expected. However, the repertoires of differentially expressed genes were found not to overlap between Hoxc8- and Hoxd4-transgenic cartilage. This included different Wnt genes, cell cycle, and apoptosis regulators. CONCLUSION Overexpression of Hoxc8 and Hoxd4 transcription factors alters transcriptional profiles in chondrocytes at E18.5. The differences in repertoires of altered gene expression between the 2 transgenic conditions suggest that the molecular mechanisms underlying the cartilage defects may be different in both transgenic paradigms, despite apparently similar phenotypes.
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Affiliation(s)
- Claudia Kruger
- Developmental Biology, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Claudia Kappen
- Developmental Biology, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
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41
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Wang Z, Iwasaki M, Ficara F, Lin C, Matheny C, Wong SHK, Smith KS, Cleary ML. GSK-3 promotes conditional association of CREB and its coactivators with MEIS1 to facilitate HOX-mediated transcription and oncogenesis. Cancer Cell 2010; 17:597-608. [PMID: 20541704 PMCID: PMC2919232 DOI: 10.1016/j.ccr.2010.04.024] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2009] [Revised: 02/23/2010] [Accepted: 04/16/2010] [Indexed: 12/24/2022]
Abstract
Acute leukemias induced by MLL chimeric oncoproteins are among the subset of cancers distinguished by a paradoxical dependence on GSK-3 kinase activity for sustained proliferation. We demonstrate here that GSK-3 maintains the MLL leukemia stem cell transcriptional program by promoting the conditional association of CREB and its coactivators TORC and CBP with homedomain protein MEIS1, a critical component of the MLL-subordinate program, which in turn facilitates HOX-mediated transcription and transformation. This mechanism also applies to hematopoietic cells transformed by other HOX genes, including CDX2, which is highly expressed in a majority of acute myeloid leukemias, thus providing a molecular approach based on GSK-3 inhibitory strategies to target HOX-associated transcription in a broad spectrum of leukemias.
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MESH Headings
- Animals
- CREB-Binding Protein/metabolism
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cyclic AMP Response Element-Binding Protein/genetics
- Cyclic AMP Response Element-Binding Protein/metabolism
- DNA-Binding Proteins/metabolism
- Down-Regulation/genetics
- Gene Expression Profiling
- Gene Expression Regulation, Leukemic/physiology
- Glycogen Synthase Kinase 3/antagonists & inhibitors
- Glycogen Synthase Kinase 3/genetics
- Glycogen Synthase Kinase 3/metabolism
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Humans
- Indoles/pharmacology
- Indoles/therapeutic use
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/prevention & control
- Maleimides/pharmacology
- Maleimides/therapeutic use
- Mice
- Mice, Inbred C57BL
- Models, Biological
- Myeloid Ecotropic Viral Integration Site 1 Protein
- Myeloid-Lymphoid Leukemia Protein/genetics
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Neoplastic Stem Cells/cytology
- Neoplastic Stem Cells/drug effects
- Neoplastic Stem Cells/metabolism
- Oncogene Proteins, Fusion/genetics
- Phosphorylation/drug effects
- Phosphorylation/physiology
- Pre-B-Cell Leukemia Transcription Factor 1
- Protein Binding/drug effects
- Protein Binding/physiology
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-fos/genetics
- Proto-Oncogene Proteins c-fos/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription, Genetic/drug effects
- Transcription, Genetic/physiology
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Affiliation(s)
- Zhong Wang
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, Ph: 650-723-5471, Fax: 650-498-6222
| | - Masayuki Iwasaki
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, Ph: 650-723-5471, Fax: 650-498-6222
| | - Francesca Ficara
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, Ph: 650-723-5471, Fax: 650-498-6222
| | - Chenwei Lin
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, Ph: 650-723-5471, Fax: 650-498-6222
| | - Christina Matheny
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, Ph: 650-723-5471, Fax: 650-498-6222
| | - Stephen H. K. Wong
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, Ph: 650-723-5471, Fax: 650-498-6222
| | - Kevin S. Smith
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, Ph: 650-723-5471, Fax: 650-498-6222
| | - Michael L. Cleary
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, Ph: 650-723-5471, Fax: 650-498-6222
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Abstract
Myeloid ecotropic insertion site (Meis)2 is a homeodomain protein containing a conserved homothorax (Hth) domain that is present in all Meis and Prep family proteins and in the Drosophila Hth protein. The Hth domain mediates interaction with Pbx homeodomain proteins, allowing for efficient DNA binding. Here we show that, like Meis1, Meis2 has a strong C-terminal transcriptional activation domain, which is required for full activation of transcription by homeodomain protein complexes composed of Meis2 and Pbx1. We also show that the activity of the activation domain is inhibited by the Hth domain, and that this autoinhibition can be partially relieved by the interaction of Pbx1 with the Hth domain of Meis2. Targeting of the Hth domain to DNA suggests that it is not a portable trans-acting repression domain. However, the Hth domain can inhibit a linked activation domain, and this inhibition is not limited to the Meis2 activation domain. Database searching reveals that the Meis3.2 splice variant, which is found in several vertebrate species, disrupts the Hth domain by removing 17 codons from the 5'-end of exon 6. We show that the equivalent deletion in Meis2 derepresses the C-terminal activation domain and weakens interaction with Pbx1. This work suggests that the transcriptional activity of all members of the Meis/Prep Hth protein family is subject to autoinhibition by their Hth domains, and that the Meis3.2 splice variant encodes a protein that bypasses this autoinhibitory effect.
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Affiliation(s)
- Cathy Hyman-Walsh
- Department of Biochemistry and Molecular Genetics, and Center for Cell Signaling, University of Virginia
| | - Glen A. Bjerke
- Department of Biochemistry and Molecular Genetics, and Center for Cell Signaling, University of Virginia
| | - David Wotton
- Department of Biochemistry and Molecular Genetics, and Center for Cell Signaling, University of Virginia
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44
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Mojsin M, Stevanovic M. PBX1 and MEIS1 up-regulate SOX3 gene expression by direct interaction with a consensus binding site within the basal promoter region. Biochem J 2009; 425:107-16. [PMID: 19799567 DOI: 10.1042/bj20090694] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sox3/SOX3 [SRY (sex determining region Y)-box 3] is considered to be one of the earliest neural markers in vertebrates, playing a role in specifying neuronal fate. We have previously reported characterization of the SOX3 promoter and demonstrated that the general transcription factors NF-Y (nuclear factor-Y), Sp1 (specificity protein 1) and USF (upstream stimulatory factor) are involved in transcriptional regulation of SOX3 promoter activity. In the present study we provide the first evidence that the TALE (three-amino-acid loop extension) transcription factors PBX1 (pre-B-cell leukaemia homeobox 1) and MEIS1 (myeloid ecotropic viral integration site 1 homologue) participate in regulating human SOX3 gene expression in NT2/D1 cells by direct interaction with the consensus PBX/MEIS-binding site, which is conserved in all mammalian orthologue promoters analysed. PBX1 is present in the protein complex formed at this site with nuclear proteins from uninduced cells, whereas both PBX1 and MEIS1 proteins were detected in the complex created with extract from RA (retinoic acid)-induced NT2/D1 cells. By functional analysis we also showed that mutations of the PBX1/MEIS1-binding sites resulted in profound reduction of SOX3 promoter responsiveness to RA. Finally, we demonstrated that overexpressed PBX1 and MEIS1 increased endogenous SOX3 protein expression in both uninduced and RA-induced NT2/D1 cells. With the results of the present study, for the first time, we have established a functional link between the TALE proteins, PBX1 and MEIS1, and expression of the human SOX3 gene. This link is of particular interest since both TALE family members and members of the SOX superfamily are recognized as important developmental regulators.
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Affiliation(s)
- Marija Mojsin
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, PO Box 23, 11010 Belgrade, Serbia
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45
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Shimabe M, Goyama S, Watanabe-Okochi N, Yoshimi A, Ichikawa M, Imai Y, Kurokawa M. Pbx1 is a downstream target of Evi-1 in hematopoietic stem/progenitors and leukemic cells. Oncogene 2009; 28:4364-74. [PMID: 19767769 DOI: 10.1038/onc.2009.288] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 07/27/2009] [Accepted: 08/17/2009] [Indexed: 12/19/2022]
Abstract
Ecotropic viral integration site-1 (Evi-1) is a nuclear transcription factor, which is essential for the proliferation/maintenance of hematopoietic stem cells (HSCs). Aberrant expression of Evi-1 has been frequently found in myeloid leukemia, and is associated with a poor patient survival. Recently, we reported candidate target genes of Evi-1 shared in HSCs and leukemic cells using gene expression profiling analysis. In this study, we identified Pbx1, a proto-oncogene in hematopoietic malignancy, as a target gene of Evi-1. Overexpression of Evi-1 increased Pbx1 expression in hematopoietic stem/progenitor cells. An analysis of the Pbx1 promoter region revealed that Evi-1 upregulates Pbx1 transcription. Furthermore, reduction of Pbx1 levels through RNAi-mediated knockdown significantly inhibited Evi-1-induced transformation. In contrast, knockdown of Pbx1 did not impair bone marrow transformation by E2A/HLF or AML1/ETO, suggesting that Pbx1 is specifically required for the maintenance of bone marrow transformation mediated by Evi-1. These results indicate that Pbx1 is a target gene of Evi-1 involved in Evi-1-mediated leukemogenesis.
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Affiliation(s)
- M Shimabe
- Department of Hematology and Oncology, Graduate school of Medicine, University of Tokyo, Tokyo, Japan
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46
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HOXA9 modulates its oncogenic partner Meis1 to influence normal hematopoiesis. Mol Cell Biol 2009; 29:5181-92. [PMID: 19620287 DOI: 10.1128/mcb.00545-09] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
While investigating the mechanism of action of the HOXA9 protein, we serendipitously identified Meis1 as a HOXA9 regulatory target. Since HOXA9 and MEIS1 play key developmental roles, are cooperating DNA binding proteins and leukemic oncoproteins, and are important for normal hematopoiesis, the regulation of Meis1 by its partner protein is of interest. Loss of Hoxa9 caused downregulation of the Meis1 mRNA and protein, while forced HOXA9 expression upregulated Meis1. Hoxa9 and Meis1 expression was correlated in hematopoietic progenitors and acute leukemias. Meis1(+/-) Hoxa9(-/-) deficient mice, generated to test HOXA9 regulation of endogenous Meis1, were small and had reduced bone marrow Meis1 mRNA and significant defects in fluorescence-activated cell sorting-enumerated monocytes, mature and pre/pro-B cells, and functional B-cell progenitors. These data indicate that HOXA9 modulates Meis1 during normal murine hematopoiesis. Chromatin immunoprecipitation analysis did not reveal direct binding of HOXA9 to Meis1 promoter/enhancer regions. However, Creb1 and Pknox1, whose protein products have previously been reported to induce Meis1, were shown to be direct targets of HOXA9. Loss of Hoxa9 resulted in a decrease in Creb1 and Pknox1 mRNA, and forced expression of CREB1 in Hoxa9(-/-) bone marrow cells increased Meis1 mRNA almost as well as HOXA9, suggesting that CREB1 may mediate HOXA9 modulation of Meis1 expression.
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47
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Hawley RG, Hawley TS, Cantor AB. TLX1 (HOX11) immortalization of embryonic stem cell-derived and primary murine hematopoietic progenitors. ACTA ACUST UNITED AC 2009; Chapter 1:Unit 1F.7. [PMID: 19085976 DOI: 10.1002/9780470151808.sc01f07s7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The ability to generate genetically engineered cell lines is of great experimental value. They provide a renewable source of material that may be suitable for biochemical analyses, chromatin immunoprecipitation assays, structure-function studies, gene function assignment, and transcription factor target gene identification. This unit describes protocols for TLX1 (HOX11)-mediated immortalization of murine hematopoietic progenitors derived from in vitro differentiated murine embryonic stem cells, or from primary mouse fetal liver or bone marrow. A wide variety of hematopoietic cell types have been immortalized using these procedures including erythroid, megakaryocytic, monocytic, myelocytic, and multipotential cell types. These lines are typically cytokine dependent for their survival and growth.
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Affiliation(s)
- Robert G Hawley
- The George Washington University Medical Center, Washington, DC, USA
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48
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Wang H, Lindsey S, Konieczna I, Bei L, Horvath E, Huang W, Saberwal G, Eklund EA. Constitutively active SHP2 cooperates with HoxA10 overexpression to induce acute myeloid leukemia. J Biol Chem 2008; 284:2549-67. [PMID: 19022774 DOI: 10.1074/jbc.m804704200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The homeodomain transcription factor HoxA10 is maximally expressed in myeloid progenitor cells. Sustained HoxA10 expression during differentiation has been described in poor prognosis human acute myeloid leukemia (AML). Consistent with this, engineered overexpression of HoxA10 in murine bone marrow induces a myeloproliferative disorder that progresses to AML over time. This murine model suggests that HoxA10 overexpression is sufficient for myeloproliferation but that differentiation block, and therefore AML, requires acquisition of additional mutations. In myeloid progenitor cells, HoxA10 represses transcription of genes that encode phagocyte effector proteins such as gp91PHOX and p67PHOX. Tyrosine phosphorylation of HoxA10 during myelopoiesis decreases binding to these target genes. In immature myeloid cells, HoxA10 also activates transcription of the DUSP4 gene that encodes Mkp2, an anti-apoptotic protein. HoxA10 binding to the DUSP4 promoter decreases during myelopoiesis. Therefore, both myeloid-specific gene repression and DUSP4 activation by HoxA10 decrease during myelopoiesis. This results in phenotypic differentiation and facilitates apoptosis as differentiation proceeds. HoxA10 is de-phosphorylated by SHP2 protein-tyrosine phosphatase in myeloid progenitors. This mechanism maintains HoxA10 in a nonphosphorylated state in immature, but not differentiating, myeloid cells. Constitutively active SHP2 mutants have been described in human AML, which dephosphorylate HoxA10 throughout myelopoiesis. In this study, we hypothesize that constitutive SHP2 activation synergizes with HoxA10 overexpression to accelerate progression to AML. Because both HoxA10 overexpression and constitutive SHP2 activation are found in poor prognosis human AML, these studies contribute to understanding biochemical aspects of disease progression in myeloid malignancy.
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Affiliation(s)
- Hao Wang
- The Feinberg School of Medicine and The Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois 60611, USA
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49
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Park JT, Shih IM, Wang TL. Identification of Pbx1, a potential oncogene, as a Notch3 target gene in ovarian cancer. Cancer Res 2008; 68:8852-60. [PMID: 18974129 PMCID: PMC2636690 DOI: 10.1158/0008-5472.can-08-0517] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Notch3 gene amplification has recently been identified in ovarian cancer but the Notch3 effectors that are involved in the development of ovarian cancer remain elusive. In this study, we have identified Pbx1, a proto-oncogene in hematopoietic malignancy, as a Notch3 target gene. Pbx1 expression is transcriptionally regulated by Notch3 activation, and Notch3/CSL protein complex directly binds to the Pbx1 promoter segment harboring the CSL-binding sequence. The growth-inhibitory effect of gamma-secretase inhibitor could be partially reversed by ectopic Pbx1 expression. Furthermore, functional studies by Pbx1 short hairpin RNA knockdown show that Pbx1 is essential for cell proliferation and tumorigenicity. Taken together, the above findings indicate that Pbx1 is a direct Notch3-regulated gene that mediates the survival signal of Notch3 in ovarian cancer.
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Affiliation(s)
- Joon T Park
- Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland
- Pathobiology Graduate Program, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Ie-Ming Shih
- Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland
- Department of Oncology, Gynecology and Obstetrics, Johns Hopkins Medical Institutions, Baltimore, Maryland
- Pathobiology Graduate Program, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Tian-Li Wang
- Department of Oncology, Gynecology and Obstetrics, Johns Hopkins Medical Institutions, Baltimore, Maryland
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50
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Fernandez LC, Errico MC, Bottero L, Penkov D, Resnati M, Blasi F, Caré A. Oncogenic HoxB7 requires TALE cofactors and is inactivated by a dominant-negative Pbx1 mutant in a cell-specific manner. Cancer Lett 2008; 266:144-55. [PMID: 18378073 DOI: 10.1016/j.canlet.2008.02.042] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 02/18/2008] [Accepted: 02/19/2008] [Indexed: 01/18/2023]
Abstract
The homeobox containing gene HoxB7 is functionally associated with melanoma growth promotion through the direct transactivation of bFGF. Accordingly, the introduction of HoxB7 in the breast cancer line SkBr3 (SkBr3/B7), strongly increases its tumorigenic properties. Here we show that in SkBr3/B7 cells, HoxB7 regulates the expression of TALE Hox cofactors by increasing Pbx2 and Prep1 and decreasing Pbx1. The functional requirement of Hox cofactors in the oncogenic activity of HoxB7 was proven with a dominant-negative Pbx1 mutant, Pbx1NT, which sequesters Prep1 in the cytoplasm. The less aggressive phenotype of the SkBr3/B7/PbxNT cells, evaluated in vitro as well as in vivo, correlated well with increased apoptosis, decreased cycling and up-regulation of p16 and p53. Tumor cell-type specific functional effects of Pbx1NT were observed, possibly related to the presence of different Hox genes in melanoma or breast adenocarcinoma DNA-protein ternary complexes.
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Affiliation(s)
- Luis C Fernandez
- IFOM, FIRC Institute of Molecular Oncology, via Adamello 16, 20126 Milan, Italy
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