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Lemma RB, Fuglerud BM, Frampton J, Gabrielsen OS. MYB: A Key Transcription Factor in the Hematopoietic System Subject to Many Levels of Control. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1459:3-29. [PMID: 39017837 DOI: 10.1007/978-3-031-62731-6_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
MYB is a master regulator and pioneer factor highly expressed in hematopoietic progenitor cells (HPCs) where it contributes to the reprogramming processes operating during hematopoietic development. MYB plays a complex role being involved in several lineages of the hematopoietic system. At the molecular level, the MYB gene is subject to intricate regulation at many levels through several enhancer and promoter elements, through transcriptional elongation control, as well as post-transcriptional regulation. The protein is modulated by post-translational modifications (PTMs) such as SUMOylation restricting the expression of its downstream targets. Together with a range of interaction partners, cooperating transcription factors (TFs) and epigenetic regulators, MYB orchestrates a fine-tuned symphony of genes expressed during various stages of haematopoiesis. At the same time, the complex MYB system is vulnerable, being a target for unbalanced control and cancer development.
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Affiliation(s)
- Roza Berhanu Lemma
- Department of Biosciences, University of Oslo, Oslo, Norway
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo, Oslo, Norway
| | | | - Jon Frampton
- Department of Cancer & Genomic Sciences, College of Medicine & Health, University of Birmingham, Edgbaston, Birmingham, UK
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Hanna GJ, Stathis A, Lopez-Miranda E, Racca F, Quon D, Leyvraz S, Hess D, Keam B, Rodon J, Ahn MJ, Kim HR, Schneeweiss A, Ribera JM, DeAngelo D, Perez Garcia JM, Cortes J, Schönborn-Kellenberger O, Weber D, Pisa P, Bauer M, Beni L, Bobadilla M, Lehal R, Vigolo M, Vogl FD, Garralda E. A Phase I Study of the Pan-Notch Inhibitor CB-103 for Patients with Advanced Adenoid Cystic Carcinoma and Other Tumors. CANCER RESEARCH COMMUNICATIONS 2023; 3:1853-1861. [PMID: 37712875 PMCID: PMC10501326 DOI: 10.1158/2767-9764.crc-23-0333] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 08/15/2023] [Accepted: 08/18/2023] [Indexed: 09/16/2023]
Abstract
PURPOSE CB-103 selectively inhibits the CSL-NICD (Notch intracellular domain) interaction leading to transcriptional downregulation of oncogenic Notch pathway activation. This dose-escalation/expansion study aimed to determine safety, pharmacokinetics, and preliminary antitumor activity. EXPERIMENTAL DESIGN Patients ≥18 years of age with selected advanced solid tumors [namely, adenoid cystic carcinoma (ACC)] and hematologic malignancies were eligible. CB-103 was dosed orally in cycles of 28 days at escalating doses until disease progression. Notch-activating mutations were required in a dose confirmatory cohort. Endpoints included dose-limiting toxicities (DLT), safety, tumor response, pharmacokinetics, and pharmacodynamics. Exploratory analyses focused on correlates of Notch and target gene expression. RESULTS Seventy-nine patients (64, 12 dose-escalation cohorts; 15, confirmatory cohort) enrolled with 54% receiving two or more lines of prior therapy. ACC was the dominant tumor type (40, 51%). Two DLTs were observed [elevated gamma-glutamyl transferase (GGT), visual change]; recommended phase II dose was declared as 500 mg twice daily (5 days on, 2 days off weekly). Grade 3-4 treatment-related adverse events occurred in 15 patients (19%), including elevated liver function tests (LFTs), anemia, and visual changes. Five (6%) discontinued drug for toxicity; with no drug-related deaths. There were no objective responses, but 37 (49%) had stable disease; including 23 of 40 (58%) patients with ACC. In the ACC cohort, median progression-free survival was 2.5 months [95% confidence interval (CI), 1.5-3.7] and median overall survival was 18.4 months (95% CI, 6.3-not reached). CONCLUSIONS CB-103 had a manageable safety profile and biological activity but limited clinical antitumor activity as monotherapy in this first-in-human study. SIGNIFICANCE CB-103 is a novel oral pan-Notch inhibitor that selectively blocks the CSL-NICD interaction leading to transcriptional downregulation of oncogenic Notch pathway activation. This first-in-human dose-escalation and -confirmation study aimed to determine the safety, pharmacokinetics, and preliminary antitumor efficacy of CB-103. We observed a favorable safety profile with good tolerability and biological activity but limited clinical single-agent antitumor activity. Some disease stabilization was observed among an aggressive NOTCH-mutant ACC type-I subgroup where prognosis is poor and therapies are critically needed. Peripheral downregulation of select Notch target gene levels was observed with escalating doses. Future studies exploring CB-103 should enrich for patients with NOTCH-mutant ACC and investigate rational combinatorial approaches in tumors where there is limited success with investigational or approved drugs.
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Affiliation(s)
- Glenn J. Hanna
- Department of Medical Oncology, Center for Head and Neck Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Anastasios Stathis
- Oncology Institute of Southern Switzerland, EOC, Bellinzona, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana (USI), Lugano, Switzerland
| | | | - Fabricio Racca
- IOB – Institute of Oncology Barcelona and Madrid, Hospital Quironsalud-Barcelona, Barcelona, Spain
| | - Doris Quon
- Sarcoma Oncology Research Center, Santa Monica, California
| | - Serge Leyvraz
- Charité Comprehensive Cancer Center, Charité Campus Benjamin Franklin, Berlin, Germany
| | - Dagmar Hess
- Department of Medical Oncology, Kantonsspital St Gallen, St Gallen, Switzerland
| | - Bhumsuk Keam
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of South Korea
| | - Jordi Rodon
- Department of Investigational Cancer Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Myung-Ju Ahn
- Samsung Medical Center Sungkyunkwan University School of Medicine, Seoul, Republic of South Korea
| | - Hye Ryun Kim
- Severance Hospital – Yonsei Cancer Center, Seoul, Republic of South Korea
| | - Andreas Schneeweiss
- National Center for Tumor Diseases (NCT), University Hospital Heidelberg and German Cancer Research Center, Heidelberg, Germany
| | - Josep-Maria Ribera
- Institut Català d'Oncologia (Catalan Institute of Oncology [ICO]), Josep Carreras Research Institute, Barcelona, Spain
| | - Daniel DeAngelo
- Division of Leukemia, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Jose Manuel Perez Garcia
- International Breast Cancer Center (IBCC), Pangaea Oncology, Quiron Hospital, Barcelona, Spain
- Medica Scientia Innovation Research, Barcelona, Spain
- Medica Scientia Innovation Research, Ridgewood, New Jersey
| | - Javier Cortes
- International Breast Cancer Center (IBCC), Pangaea Oncology, Quiron Hospital, Barcelona, Spain
- Medica Scientia Innovation Research, Barcelona, Spain
- Medica Scientia Innovation Research, Ridgewood, New Jersey
| | | | - Dirk Weber
- Cellestia Biotech AG, Basel, Switzerland
| | - Pavel Pisa
- piMedConsulting Ltd, Gersau, Switzerland
| | | | - Laura Beni
- Cellestia Biotech AG, Basel, Switzerland
| | | | - Raj Lehal
- Cellestia Biotech AG, Basel, Switzerland
| | | | | | - Elena Garralda
- Early Drug Development Unit, Clinical Research Program, Vall d'Hebron University Hospital and Institute of Oncology (VHIO) and Medical Oncology, Vall d'Hebron University Hospital (HUVH), Barcelona, Spain
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Lemma RB, Ledsaak M, Fuglerud BM, Sandve GK, Eskeland R, Gabrielsen OS. Chromatin occupancy and target genes of the haematopoietic master transcription factor MYB. Sci Rep 2021; 11:9008. [PMID: 33903675 PMCID: PMC8076236 DOI: 10.1038/s41598-021-88516-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 04/13/2021] [Indexed: 02/02/2023] Open
Abstract
The transcription factor MYB is a master regulator in haematopoietic progenitor cells and a pioneer factor affecting differentiation and proliferation of these cells. Leukaemic transformation may be promoted by high MYB levels. Despite much accumulated molecular knowledge of MYB, we still lack a comprehensive understanding of its target genes and its chromatin action. In the present work, we performed a ChIP-seq analysis of MYB in K562 cells accompanied by detailed bioinformatics analyses. We found that MYB occupies both promoters and enhancers. Five clusters (C1-C5) were found when we classified MYB peaks according to epigenetic profiles. C1 was enriched for promoters and C2 dominated by enhancers. C2-linked genes were connected to hematopoietic specific functions and had GATA factor motifs as second in frequency. C1 had in addition to MYB-motifs a significant frequency of ETS-related motifs. Combining ChIP-seq data with RNA-seq data allowed us to identify direct MYB target genes. We also compared ChIP-seq data with digital genomic footprinting. MYB is occupying nearly a third of the super-enhancers in K562. Finally, we concluded that MYB cooperates with a subset of the other highly expressed TFs in this cell line, as expected for a master regulator.
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Affiliation(s)
- Roza B Lemma
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo, 0318, Oslo, Norway
| | - Marit Ledsaak
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway
- Institute of Basic Medical Sciences, Department of Molecular Medicine, University of Oslo, Blindern, PO Box 1112, 0317, Oslo, Norway
| | - Bettina M Fuglerud
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway
- Terry Fox Laboratory, BC Cancer, Vancouver, BC, V5Z 1L3, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Geir Kjetil Sandve
- Department of Informatics, University of Oslo, Blindern, PO Box 1080, 0371, Oslo, Norway
| | - Ragnhild Eskeland
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway
- Institute of Basic Medical Sciences, Department of Molecular Medicine, University of Oslo, Blindern, PO Box 1112, 0317, Oslo, Norway
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Odd S Gabrielsen
- Department of Biosciences, University of Oslo, Blindern, PO Box 1066, 0316, Oslo, Norway.
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Ferrarotto R, Mitani Y, McGrail DJ, Li K, Karpinets TV, Bell D, Frank SJ, Song X, Kupferman ME, Liu B, Lee JJ, Glisson BS, Zhang J, Aster JC, Lin SY, Futreal PA, Heymach JV, El-Naggar AK. Proteogenomic Analysis of Salivary Adenoid Cystic Carcinomas Defines Molecular Subtypes and Identifies Therapeutic Targets. Clin Cancer Res 2020; 27:852-864. [PMID: 33172898 DOI: 10.1158/1078-0432.ccr-20-1192] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 08/10/2020] [Accepted: 11/04/2020] [Indexed: 11/16/2022]
Abstract
PURPOSE Salivary gland adenoid cystic carcinoma (ACC) has heterogeneous clinical behavior. Currently, all patients are treated uniformly, and no standard-of-care systemic therapy exists for metastatic ACC. We conducted an integrated proteogenomic analyses of ACC tumors to identify dysregulated pathways and propose a classification with therapeutic implications. EXPERIMENTAL DESIGN RNA/DNA sequencing of 54 flash-frozen salivary ACCs and reverse phase protein array (RPPA) in 38 specimens were performed, with validation by Western blotting and/or IHC. Three independent ACC cohorts were used for validation. RESULTS Both unbiased RNA sequencing (RNA-seq) and RPPA analysis revealed two molecular subtypes: ACC-I (37%) and ACC-II (63%). ACC-I had strong upregulation of MYC, MYC target genes, and mRNA splicing, enrichment of NOTCH-activating mutations, and dramatically worse prognosis. ACC-II exhibited upregulation of TP63 and receptor tyrosine kinases (AXL, MET, and EGFR) and less aggressive clinical course. TP63 and MYC were sufficient to assign tumors to ACC subtypes, which was validated in one independent cohort by IHC and two additional independent cohorts by RNA-seq. Furthermore, IHC staining for MYC and P63 protein levels can be used to identify ACC subtypes, enabling rapid clinical deployment to guide therapeutic decisions. Our data suggest a model in which ACC-I is driven by MYC signaling through either NOTCH mutations or direct amplification, which in turn suppress P63 signaling observed in ACC-II, producing unique therapeutic vulnerabilities for each subtype. CONCLUSIONS Cooccurrence of multiple actionable protein/pathways alterations in each subtype indicates unique therapeutic vulnerabilities and opportunities for optimal combination therapy for this understudied and heterogeneous disease.
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Affiliation(s)
- Renata Ferrarotto
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
| | - Yoshitsugu Mitani
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Daniel J McGrail
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Kaiyi Li
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Tatiana V Karpinets
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Diana Bell
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Steven J Frank
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Xingzhi Song
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Michael E Kupferman
- Department of Head and Neck Surgery, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Bin Liu
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - J Jack Lee
- Department of Statistics, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Bonnie S Glisson
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Jianhua Zhang
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Jon C Aster
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts
| | - Shiaw-Yih Lin
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - P Andrew Futreal
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - John V Heymach
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Adel K El-Naggar
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas
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Nguyen DTT, Lu Y, Chu KL, Yang X, Park SM, Choo ZN, Chin CR, Prieto C, Schurer A, Barin E, Savino AM, Gourkanti S, Patel P, Vu LP, Leslie CS, Kharas MG. HyperTRIBE uncovers increased MUSASHI-2 RNA binding activity and differential regulation in leukemic stem cells. Nat Commun 2020; 11:2026. [PMID: 32332729 PMCID: PMC7181745 DOI: 10.1038/s41467-020-15814-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 03/25/2020] [Indexed: 01/16/2023] Open
Abstract
The cell-context dependency for RNA binding proteins (RBPs) mediated control of stem cell fate remains to be defined. Here we adapt the HyperTRIBE method using an RBP fused to a Drosophila RNA editing enzyme (ADAR) to globally map the mRNA targets of the RBP MSI2 in mammalian adult normal and malignant stem cells. We reveal a unique MUSASHI-2 (MSI2) mRNA binding network in hematopoietic stem cells that changes during transition to multipotent progenitors. Additionally, we discover a significant increase in RNA binding activity of MSI2 in leukemic stem cells compared with normal hematopoietic stem and progenitor cells, resulting in selective regulation of MSI2's oncogenic targets. This provides a basis for MSI2 increased dependency in leukemia cells compared to normal cells. Moreover, our study provides a way to measure RBP function in rare cells and suggests that RBPs can achieve differential binding activity during cell state transition independent of gene expression.
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Affiliation(s)
- Diu T T Nguyen
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Yuheng Lu
- Computational Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Blavatnik Institute of System Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Karen L Chu
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
- Weill Cornell School of Medical Sciences, New York, NY, 10065, USA
| | - Xuejing Yang
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Sun-Mi Park
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Zi-Ning Choo
- Weill Cornell School of Medical Sciences, New York, NY, 10065, USA
| | | | - Camila Prieto
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Alexandra Schurer
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Ersilia Barin
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Angela M Savino
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Saroj Gourkanti
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Payal Patel
- Weill Cornell School of Medical Sciences, New York, NY, 10065, USA
| | - Ly P Vu
- Terry Fox Laboratory, British Columbia Cancer Research Centre, Vancouver, BC, V5Z 1L3, Canada
- Molecular Biology and Biochemistry, Simon Fraser University, Vancouver, BC, V5A 1S6, Canada
| | - Christina S Leslie
- Computational Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Michael G Kharas
- Molecular Pharmacology Program, Center for Cell Engineering, Center for Stem Cell Biology, Center for Experimental Therapeutics, Center for Hematologic Malignancies, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA.
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Wang X, Angelis N, Thein SL. MYB - A regulatory factor in hematopoiesis. Gene 2018; 665:6-17. [PMID: 29704633 PMCID: PMC10764194 DOI: 10.1016/j.gene.2018.04.065] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/06/2018] [Accepted: 04/23/2018] [Indexed: 01/07/2023]
Abstract
MYB is a transcription factor which was identified in birds as a viral oncogene (v-MYB). Its cellular counterpart was subsequently isolated as c-MYB which has three functional domains - DNA binding domain, transactivation domain and negative regulatory domain. c-MYB is essential for survival, and deletion of both alleles of the gene results in embryonic death. It is highly expressed in hematopoietic cells, thymus and neural tissue, and required for T and B lymphocyte development and erythroid maturation. Additionally, aberrant MYB expression has been found in numerous solid cancer cells and human leukemia. Recent studies have also implicated c-MYB in the regulation of expression of fetal hemoglobin which is highly beneficial to the β-hemoglobinopathies (beta thalassemia and sickle cell disease). These findings suggest that MYB could be a potential therapeutic target in leukemia, and possibly also a target for therapeutic increase of fetal hemoglobin in the β-hemoglobinopathies.
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Affiliation(s)
- Xunde Wang
- National Heart, Lung and Blood Institute/NIH, Sickle Cell Branch, Bethesda, USA
| | - Nikolaos Angelis
- National Heart, Lung and Blood Institute/NIH, Sickle Cell Branch, Bethesda, USA
| | - Swee Lay Thein
- National Heart, Lung and Blood Institute/NIH, Sickle Cell Branch, Bethesda, USA.
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Targeting acute myeloid leukemia with a small molecule inhibitor of the Myb/p300 interaction. Blood 2015; 127:1173-82. [PMID: 26631113 DOI: 10.1182/blood-2015-09-668632] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 11/19/2015] [Indexed: 12/17/2022] Open
Abstract
The transcription factor Myb plays a key role in the hematopoietic system and has been implicated in the development of leukemia and other human cancers. Inhibition of Myb is therefore emerging as a potential therapeutic strategy for these diseases. However, because of a lack of suitable inhibitors, the feasibility of therapeutic approaches based on Myb inhibition has not been explored. We have identified the triterpenoid Celastrol as a potent low-molecular-weight inhibitor of the interaction of Myb with its cooperation partner p300. We demonstrate that Celastrol suppresses the proliferative potential of acute myeloid leukemia (AML) cells while not affecting normal hematopoietic progenitor cells. Furthermore, Celastrol prolongs the survival of mice in a model of an aggressive AML. Overall, our work demonstrates the therapeutic potential of a small molecule inhibitor of the Myb/p300 interaction for the treatment of AML and provides a starting point for the further development of Myb-inhibitory compounds for the treatment of leukemia and, possibly, other tumors driven by deregulated Myb.
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Abstract
Strict control of tissue-specific gene expression plays a pivotal role during lineage commitment. The transcription factor c-Myb has an essential role in adult haematopoiesis and functions as an oncogene when rearranged in human cancers. Here we have exploited digital genomic footprinting analysis to obtain a global picture of c-Myb occupancy in the genome of six different haematopoietic cell-types. We have biologically validated several c-Myb footprints using c-Myb knockdown data, reporter assays and DamID analysis. We show that our predicted conserved c-Myb footprints are highly dependent on the haematopoietic cell type, but that there is a group of gene targets common to all cell-types analysed. Furthermore, we find that c-Myb footprints co-localise with active histone mark H3K4me3 and are significantly enriched at exons. We analysed co-localisation of c-Myb footprints with 104 chromatin regulatory factors in K562 cells, and identified nine proteins that are enriched together with c-Myb footprints on genes positively regulated by c-Myb and one protein enriched on negatively regulated genes. Our data suggest that c-Myb is a transcription factor with multifaceted target regulation depending on cell type.
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Uttarkar S, Dukare S, Bopp B, Goblirsch M, Jose J, Klempnauer KH. Naphthol AS-E Phosphate Inhibits the Activity of the Transcription Factor Myb by Blocking the Interaction with the KIX Domain of the Coactivator p300. Mol Cancer Ther 2015; 14:1276-85. [PMID: 25740244 DOI: 10.1158/1535-7163.mct-14-0662] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 01/16/2015] [Indexed: 11/16/2022]
Abstract
The transcription factor c-Myb is highly expressed in hematopoietic progenitor cells and controls the transcription of genes important for lineage determination, cell proliferation, and differentiation. Deregulation of c-Myb has been implicated in the development of leukemia and certain other types of human cancer. c-Myb activity is highly dependent on the interaction of the c-Myb with the KIX domain of the coactivator p300, making the disruption of this interaction a reasonable strategy for the development of Myb inhibitors. Here, we have used bacterial Autodisplay to develop an in vitro binding assay that mimics the interaction of Myb and the KIX domain of p300. We have used this binding assay to investigate the potential of Naphthol AS-E phosphate, a compound known to bind to the KIX domain, to disrupt the interaction between Myb and p300. Our data show that Naphthol AS-E phosphate interferes with the Myb-KIX interaction in vitro and inhibits Myb activity in vivo. By using several human leukemia cell lines, we demonstrate that Naphthol AS-E phosphate suppresses the expression of Myb target genes and induces myeloid differentiation and apoptosis. Our work identifies Naphthol AS-E phosphate as the first low molecular weight compound that inhibits Myb activity by disrupting its interaction with p300, and suggests that inhibition of the Myb-KIX interaction might be a useful strategy for the treatment of leukemia and other tumors caused by deregulated c-Myb.
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Affiliation(s)
- Sagar Uttarkar
- Institute for Biochemistry, Westfälische-Wilhelms-Universität Münster, Münster, Germany. Graduate School of Chemistry (GSC-MS), Westfälische-Wilhelms-Universität Münster, Münster, Germany
| | - Sandeep Dukare
- Institute for Biochemistry, Westfälische-Wilhelms-Universität Münster, Münster, Germany. Graduate School of Chemistry (GSC-MS), Westfälische-Wilhelms-Universität Münster, Münster, Germany
| | - Bertan Bopp
- Institute for Pharmaceutical and Medicinal Chemistry, Westfälische-Wilhelms-Universität Münster, Münster, Germany
| | - Michael Goblirsch
- Institute for Pharmaceutical and Medicinal Chemistry, Westfälische-Wilhelms-Universität Münster, Münster, Germany
| | - Joachim Jose
- Institute for Pharmaceutical and Medicinal Chemistry, Westfälische-Wilhelms-Universität Münster, Münster, Germany
| | - Karl-Heinz Klempnauer
- Institute for Biochemistry, Westfälische-Wilhelms-Universität Münster, Münster, Germany.
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Situational awareness: regulation of the myb transcription factor in differentiation, the cell cycle and oncogenesis. Cancers (Basel) 2014; 6:2049-71. [PMID: 25279451 PMCID: PMC4276956 DOI: 10.3390/cancers6042049] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 08/11/2014] [Accepted: 09/26/2014] [Indexed: 12/02/2022] Open
Abstract
This review summarizes the mechanisms that control the activity of the c-Myb transcription factor in normal cells and tumors, and discusses how c-Myb plays a role in the regulation of the cell cycle. Oncogenic versions of c-Myb contribute to the development of leukemias and solid tumors such as adenoid cystic carcinoma, breast cancer and colon cancer. The activity and specificity of the c-Myb protein seems to be controlled through changes in protein-protein interactions, so understanding how it is regulated could lead to the development of novel therapeutic strategies.
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Pieraccioli M, Imbastari F, Antonov A, Melino G, Raschellà G. Activation of miR200 by c-Myb depends on ZEB1 expression and miR200 promoter methylation. Cell Cycle 2014; 12:2309-20. [PMID: 24067373 DOI: 10.4161/cc.25405] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Tumor progression to metastasis is a complex, sequential process that requires proliferation, resistance to apoptosis, motility and invasion to colonize at distant sites. The acquisition of these features implies a phenotypic plasticity by tumor cells that must adapt to different conditions by modulating several signaling pathways (1) during the journey to the final site of metastasis. Several transcription factors and microRNA play a role in tumor progression, but less is known about the control of their expression during this process. Here, we demonstrate by ectopic expression and gene silencing that the proto-oncogene c-Myb activates the expression of the 5 members of miR200 family (miR200b, miR200a, miR429, miR200c and miR141) that are involved in the control of epithelial-mesenchymal transition (EMT) and metastasis in many types of cancers. Transcriptional activation of miR200 by c-Myb occurs through binding to myb binding sites located in the promoter regions of miR200 genes on human chromosomes 1 and 12. Furthermore, when c-Myb and the transcriptional repressor ZEB1 are co-expressed, as at the onset EMT, the repression by ZEB1 prevails over the activation by c-Myb, and the expression of miR200 is inhibited. We also demonstrate that during EMT induced by TGF-β, the promoters of miR200 genes are methylated, and their transcription is repressed regardless of the presence of repressors such as ZEB1 and activators such as c-Myb. Finally, we find a correlation between the expression of c-Myb and that of four out of 5 miR200 in a data set of 207 breast cancer patients.
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Affiliation(s)
- Marco Pieraccioli
- ENEA Research Center Casaccia, Radiation Biology and Human Health Unit, Rome, Italy
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12
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ZRF1 controls the retinoic acid pathway and regulates leukemogenic potential in acute myeloid leukemia. Oncogene 2013; 33:5501-10. [DOI: 10.1038/onc.2013.501] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 10/15/2013] [Accepted: 10/18/2013] [Indexed: 11/09/2022]
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13
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Streubel G, Bouchard C, Berberich H, Zeller MS, Teichmann S, Adamkiewicz J, Müller R, Klempnauer KH, Bauer UM. PRMT4 is a novel coactivator of c-Myb-dependent transcription in haematopoietic cell lines. PLoS Genet 2013; 9:e1003343. [PMID: 23505388 PMCID: PMC3591284 DOI: 10.1371/journal.pgen.1003343] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Accepted: 01/10/2013] [Indexed: 01/10/2023] Open
Abstract
Protein arginine methyltransferase 4 (PRMT4)–dependent methylation of arginine residues in histones and other chromatin-associated proteins plays an important role in the regulation of gene expression. However, the exact mechanism of how PRMT4 activates transcription remains elusive. Here, we identify the chromatin remodeller Mi2α as a novel interaction partner of PRMT4. PRMT4 binds Mi2α and its close relative Mi2β, but not the other components of the repressive Mi2-containing NuRD complex. In the search for the biological role of this interaction, we find that PRMT4 and Mi2α/β interact with the transcription factor c-Myb and cooperatively coactivate c-Myb target gene expression in haematopoietic cell lines. This coactivation requires the methyltransferase and ATPase activity of PRMT4 and Mi2, respectively. Chromatin immunoprecipitation analysis shows that c-Myb target genes are direct transcriptional targets of PRMT4 and Mi2. Knockdown of PRMT4 or Mi2α/β in haematopoietic cells of the erythroid lineage results in diminished transcriptional induction of c-Myb target genes, attenuated cell growth and survival, and deregulated differentiation resembling the effects caused by c-Myb depletion. These findings reveal an important and so far unknown connection between PRMT4 and the chromatin remodeller Mi2 in c-Myb signalling. Our manuscript deals with the Protein arginine methyltransferase 4 (PRMT4), which modifies arginine residues in histones and other chromatin-associated proteins and plays an important role in the regulation of gene expression. We addressed the question of how the transcriptional function of PRMT4 might contribute to cell lineage specification despite its ubiquitious expression pattern and how this could explain its involvement in tumorigenesis. As protein associations are likely to provide an answer to this question, we attempted to identify novel interaction partners of PRMT4 using a biochemical approach. By this means, we found that PRMT4 binds Mi2α and its close relative Mi2β. In the search for the biological role of this interaction, we found that PRMT4 and Mi2α/β interact with the transcription factor c-Myb and cooperatively coactivate c-Myb target gene expression in haematopoietic cell lines. Depletion of PRMT4 or Mi2α/β in human erythroleukemia cells resulted in deregulated cell proliferation and differentiation resembling the effects caused by c-Myb depletion. Our findings unravel an important and so far unknown connection between PRMT4 and the chromatin remodeller Mi2 in c-Myb signalling and gene activation and identify both coregulators as attractive targets for leukaemia research and therapy in the future.
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Affiliation(s)
- Gundula Streubel
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Caroline Bouchard
- Institute for Molecular Biology and Tumor Research (IMT), University of Marburg, Marburg, Germany
| | - Hannah Berberich
- Institute for Molecular Biology and Tumor Research (IMT), University of Marburg, Marburg, Germany
| | - Marc S. Zeller
- Institute for Molecular Biology and Tumor Research (IMT), University of Marburg, Marburg, Germany
| | | | - Jürgen Adamkiewicz
- Institute for Molecular Biology and Tumor Research (IMT), University of Marburg, Marburg, Germany
| | - Rolf Müller
- Institute for Molecular Biology and Tumor Research (IMT), University of Marburg, Marburg, Germany
| | - Karl-Heinz Klempnauer
- Institute for Biochemistry, Westfälische Wilhelms-University of Münster, Münster, Germany
| | - Uta-Maria Bauer
- Institute for Molecular Biology and Tumor Research (IMT), University of Marburg, Marburg, Germany
- * E-mail:
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Schomburg C, Schuehly W, Da Costa FB, Klempnauer KH, Schmidt TJ. Natural sesquiterpene lactones as inhibitors of Myb-dependent gene expression: structure-activity relationships. Eur J Med Chem 2013; 63:313-20. [PMID: 23501116 DOI: 10.1016/j.ejmech.2013.02.018] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 02/12/2013] [Accepted: 02/15/2013] [Indexed: 11/26/2022]
Abstract
c-myb is a proto-oncogene encoding a transcription factor which is highly expressed in hematopoietic progenitor cells. It regulates the expression of genes important for lineage determination, cell proliferation, and differentiation. Deregulation of c-myb expression is known to be involved in the development of human tumors, especially certain types of leukemia and breast and colon cancer. The c-Myb protein has thus been identified as an interesting therapeutic target. We recently discovered that some sesquiterpene lactones suppress Myb-dependent gene expression which is a new mechanism for these natural products' potential anti-cancer activity. We developed a test system to screen compounds for inhibitory activity on Myb-inducible reporter gene activation. Using this system we have now investigated 60 sesquiterpene lactones for their capacity to inhibit c-Myb-dependent gene activation. The IC50 values were in a range between 0.7 and >30 μM. The furanoheliangolide goyazensolide and the pseudoguaianolide helenalin acetate (IC50 = 0.6 and 0.7 μM, respectively) represent the most active inhibitors of c-Myb dependent gene expression found up to present. Control measurements for cell viability (MTS assay) proved that the observed activity on c-Myb dependent gene expression is not a function of cytotoxicity/unspecific cell damage. Structure-activity relationships were investigated by a QSAR approach based on flexible alignment of the most active compounds and a common pharmacophore model. These investigations resulted in a QSAR model which indicates that the potency of inhibitory activity on c-Myb-dependent transcription does not only depend on the presence of reactive Michael-acceptor features but also on their optimal spatial arrangement in the molecule.
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Affiliation(s)
- Caroline Schomburg
- Institute of Pharmaceutical Biology and Phytochemistry (IPBP), University of Münster, Hittorfstr. 56, D-48149 Münster, Germany
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Prouse MB, Campbell MM. The interaction between MYB proteins and their target DNA binding sites. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1819:67-77. [DOI: 10.1016/j.bbagrm.2011.10.010] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 10/17/2011] [Accepted: 10/18/2011] [Indexed: 02/02/2023]
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Bujnicki T, Wilczek C, Schomburg C, Feldmann F, Schlenke P, Müller-Tidow C, Schmidt TJ, Klempnauer KH. Inhibition of Myb-dependent gene expression by the sesquiterpene lactone mexicanin-I. Leukemia 2011; 26:615-22. [PMID: 21986841 DOI: 10.1038/leu.2011.275] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The c-myb proto-oncogene encodes a transcription factor that is highly expressed in the progenitor cells of the hematopoietic system, where it regulates the expression of genes important for lineage determination, cell proliferation and differentiation. There is strong evidence that deregulation of c-myb expression is involved in the development of human tumors, particularly of certain types of leukemia, and breast and colon cancer. The c-Myb protein is therefore an interesting therapeutic target. Here, we have investigated the potential of natural sesquiterpene lactones (STLs), a class of compounds that are active constituents of a variety of medicinal plants, to suppress Myb-dependent gene expression. We have developed a test system that allows screening of compounds for their ability to interfere with the activation of Myb target genes. Using this assay system, we have identified the STL mexicanin-I as the first cell-permeable, low-molecular-weight inhibitor of Myb-induced gene expression.
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Affiliation(s)
- T Bujnicki
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, Münster, Germany
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Alm-Kristiansen AH, Lorenzo PI, Molværsmyr AK, Matre V, Ledsaak M, Sæther T, Gabrielsen OS. PIAS1 interacts with FLASH and enhances its co-activation of c-Myb. Mol Cancer 2011; 10:21. [PMID: 21338522 PMCID: PMC3050860 DOI: 10.1186/1476-4598-10-21] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Accepted: 02/21/2011] [Indexed: 11/15/2022] Open
Abstract
Background FLASH is a huge nuclear protein involved in various cellular functions such as apoptosis signalling, NF-κB activation, S-phase regulation, processing of histone pre-mRNAs, and co-regulation of transcription. Recently, we identified FLASH as a co-activator of the transcription factor c-Myb and found FLASH to be tightly associated with active transcription foci. As a huge multifunctional protein, FLASH is expected to have many interaction partners, some which may shed light on its function as a transcriptional regulator. Results To find additional FLASH-associated proteins, we performed a yeast two-hybrid (Y2H) screening with FLASH as bait and identified the SUMO E3 ligase PIAS1 as an interaction partner. The association appears to involve two distinct interaction surfaces in FLASH. We verified the interaction by Y2H-mating, GST pulldowns, co-IP and ChIP. FLASH and PIAS1 were found to co-localize in nuclear speckles. Functional assays revealed that PIAS1 enhances the intrinsic transcriptional activity of FLASH in a RING finger-dependent manner. Furthermore, PIAS1 also augments the specific activity of c-Myb, and cooperates with FLASH to further co-activate c-Myb. The three proteins, FLASH, PIAS1, and c-Myb, are all co-localized with active RNA polymerase II foci, resembling transcription factories. Conclusions We conclude that PIAS1 is a common partner for two cancer-related nuclear factors, c-Myb and FLASH. Our results point to a functional cooperation between FLASH and PIAS1 in the enhancement of c-Myb activity in active nuclear foci.
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Tanno B, Sesti F, Cesi V, Bossi G, Ferrari-Amorotti G, Bussolari R, Tirindelli D, Calabretta B, Raschellà G. Expression of Slug is regulated by c-Myb and is required for invasion and bone marrow homing of cancer cells of different origin. J Biol Chem 2010; 285:29434-45. [PMID: 20622260 DOI: 10.1074/jbc.m109.089045] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In metastatic cancer cells, the process of invasion is regulated by several transcription factors that induce changes required for migration and resistance to apoptosis. Slug (SNAI2, Snail2) is involved in epithelial mesenchymal transition in physiological and in pathological contexts. We show here that in embryonic kidney, colon carcinoma, chronic myeloid leukemia-blast crisis, and in neuroblastoma cells, expression of Slug is transcriptionally regulated by c-Myb via Myb binding sites in the 5'-flanking region and in the first intron of the slug gene. In embryonic kidney and neuroblastoma cells, c-Myb induced vimentin, fibronectin, and N-cadherin expression and membrane ruffling via actin polymerization consistent with the acquisition of a mesenchymal-like phenotype. Furthermore, down-regulation of endogenous c-Myb levels in colon carcinoma cells led to increased expression of E-cadherin and reduced levels of vimentin. Some of these changes are predominantly Slug-dependent as Slug silencing via RNA interference (RNAi) reverts the cells to a quasi-parental condition. Changes in gene expression and morphology induced by c-Myb-activated Slug correlated with increased ability to migrate (embryonic kidney) and to invade through a Matrigel membrane (embryonic kidney, colon carcinoma, neuroblastoma). c-Myb-dependent Slug expression was also essential for the homing of chronic myeloid leukemia K562 cells to the bone marrow. In summary, we show here that the proto-oncogene c-Myb controls Slug transcription in tumor cells of different origin. Such a regulatory pathway contributes to the acquisition of invasive properties that are important for the metastatic process.
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Affiliation(s)
- Barbara Tanno
- Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Research Center Casaccia, Laboratory of Radiation Biology and Biomedicine, 00123 Rome, Italy
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Mitochondrial Hep27 is a c-Myb target gene that inhibits Mdm2 and stabilizes p53. Mol Cell Biol 2010; 30:3981-93. [PMID: 20547751 DOI: 10.1128/mcb.01284-09] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ever-expanding knowledge of the role of p53 in cellular metabolism, apoptosis, and cell cycle control has led to increasing interest in defining the stress response pathways that regulate Mdm2. In an effort to identify novel Mdm2 binding partners, we performed a large-scale immunoprecipitation of Mdm2 in the osteosarcoma U2OS cell line. One significant binding protein identified was Hep27, a member of the short-chain alcohol dehydrogenase/reductase (SDR) family of enzymes. Here, we demonstrate that the Hep27 preprotein contains an N-terminal mitochondrial targeting signal that is cleaved following mitochondrial import, resulting in mitochondrial matrix accumulation of mature Hep27. A fraction of the mitochondrial Hep27 translocates to the nucleus, where it binds to Mdm2 in the central domain, resulting in the attenuation of Mdm2-mediated p53 degradation. In addition, Hep27 is regulated at the transcriptional level by the proto-oncogene c-Myb and is required for c-Myb-induced p53 stabilization. Breast cancer gene expression analysis correlated estrogen receptor (ER) status with Hep27 expression and p53 function, providing a potential in vivo link between estrogen receptor signaling and p53 activity. Our data demonstrate a unique c-Myb-Hep27-Mdm2-p53 mitochondria-to-nucleus signaling pathway that may have functional significance for ER-positive breast cancers.
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Molvaersmyr AK, Saether T, Gilfillan S, Lorenzo PI, Kvaløy H, Matre V, Gabrielsen OS. A SUMO-regulated activation function controls synergy of c-Myb through a repressor-activator switch leading to differential p300 recruitment. Nucleic Acids Res 2010; 38:4970-84. [PMID: 20385574 PMCID: PMC2926607 DOI: 10.1093/nar/gkq245] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Synergy between transcription factors operating together on complex promoters is a key aspect of gene activation. The ability of specific factors to synergize is restricted by sumoylation (synergy control, SC). Focusing on the haematopoietic transcription factor c-Myb, we found evidence for a strong SC linked to SUMO-conjugation in its negative regulatory domain (NRD), while AMV v-Myb has escaped this control. Mechanistic studies revealed a SUMO-dependent switch in the function of NRD. When NRD is sumoylated, the activity of c-Myb is reduced. When sumoylation is abolished, NRD switches into being activating, providing the factor with a second activation function (AF). Thus, c-Myb harbours two AFs, one that is constitutively active and one in the NRD being SUMO-regulated (SRAF). This double AF augments c-Myb synergy at compound natural promoters. A similar SUMO-dependent switch was observed in the regulatory domains of Sp3 and p53. We show that the change in synergy behaviour correlates with a SUMO-dependent differential recruitment of p300 and a corresponding local change in histone H3 and H4 acetylation. We therefore propose a general model for SUMO-mediated SC, where SUMO controls synergy by determining the number and strength of AFs associated with a promoter leading to differential chromatin signatures.
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Fang F, Rycyzyn MA, Clevenger CV. Role of c-Myb during prolactin-induced signal transducer and activator of transcription 5a signaling in breast cancer cells. Endocrinology 2009; 150:1597-606. [PMID: 19036881 PMCID: PMC2659289 DOI: 10.1210/en.2008-1079] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Accepted: 11/14/2008] [Indexed: 01/17/2023]
Abstract
Implicated in the pathogenesis of breast cancer, prolactin (PRL) mediates its function in part through the prolactin receptor (PRLr)-associated Janus kinase 2 (Jak2)/signal transducer and activator of transcription 5 (Stat5) signaling complex. To delineate the mechanisms of Stat5a regulation in breast cancer, transcription factor-transcription factor (TF-TF) array analysis was employed to identify associated transcriptional regulators. These analyses revealed a PRL-inducible association of Stat5a with the transcription factor and protooncogene c-Myb. Confirmatory co-immunoprecipitation studies using lysates from both T47D and MCF7 breast cancer cells revealed a PRL-inducible association between these transcription factors. Ectopic expression of c-Myb enhanced the PRL-induced expression from both composite and synthetic Stat5a-responsive luciferase reporters. Chromatin immunoprecipitation assays also revealed a PRL-inducible association between c-Myb and endogenous Stat5a-responsive CISH promoter, which was associated with an enhanced expression of CISH gene product at the RNA and protein levels. Small interfering RNA-mediated c-Myb knockdown impaired the PRL-induced mRNA expression of five Stat5-responsive genes. DNA binding-defective mutants of c-Myb, incapable of activating expression from a c-Myb-responsive reporter, maintained their ability to enhance a Stat5a-responsive reporter. At a cellular level, ectopic expression of c-Myb resulted in an increase in T47D proliferation. Taken together, these results indicate that c-Myb potentiates Stat5a-driven gene expression, possibly functioning as a Stat5a coactivator, in human breast cancer.
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Affiliation(s)
- Feng Fang
- Department of Pathology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, Illinois 60611, USA
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Rønneberg JA, Tost J, Solvang HK, Alnaes GIG, Johansen FE, Brendeford EM, Yakhini Z, Gut IG, Lønning PE, Børresen-Dale AL, Gabrielsen OS, Kristensen VN. GSTP1 promoter haplotypes affect DNA methylation levels and promoter activity in breast carcinomas. Cancer Res 2008; 68:5562-71. [PMID: 18632608 DOI: 10.1158/0008-5472.can-07-5828] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The CpG island spanning the transcription start of the glutathione S-transferase P1 becomes methylated in a variety of human cancers including breast cancer. To study the effect of sequence variation on hypermethylation of the GSTP1 promoter, we analyzed the genetic and epigenetic variability in 90 tumors from patients with locally advanced breast cancer. High-resolution quantitative analysis revealed large variability in the DNA methylation levels. Lack of methylation was more often observed in the basal and normal-like estrogen receptor (ER)-negative tumors, and methylated GSTP1 was associated with better overall survival (P = 0.00063). Studies of the genetic variation identified 14 different haplotypes. The distribution of methylation levels of tumors homozygous for the most frequent haplotype was significantly different from other haplotype combinations (P = 0.011), the difference being more pronounced in ER-positive (P = 0.005) and progesterone receptor-positive (P = 0.008) tumors. Regression modeling identified the ER status and haplotype as the main determinants of DNA methylation variability. We identified a putative c-Myb response element (MRE) that was present in one of two minimal promoter haplotypes. In vitro analysis showed that c-Myb binds to the MRE, but binding was weakened by the two polymorphisms. Transient cotransfections in luminal-type and basal-like breast cancer cell lines confirmed cell-specific differential binding of c-Myb to the polymorphic sites, leading to a change in the expression from the GSTP1 promoter in vivo. GSTP1 expression was moderately but significantly (P = 0.01) reduced after siRNA-mediated knockdown of c-Myb. Our results indicate that haplotype structure of a promoter is important for the extent of DNA methylation.
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Affiliation(s)
- Jo Anders Rønneberg
- Department of Genetics, The Norwegian Radium Hospital, Rikshospitalet University Hospital, Montebello, Oslo, Norway
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Greig KT, Carotta S, Nutt SL. Critical roles for c-Myb in hematopoietic progenitor cells. Semin Immunol 2008; 20:247-56. [PMID: 18585056 DOI: 10.1016/j.smim.2008.05.003] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2007] [Accepted: 05/14/2008] [Indexed: 11/16/2022]
Abstract
While it has long been known that the transcription factor c-Myb is an essential regulator of hematopoiesis, its precise molecular targets have remained elusive. Cell line studies suggest that c-Myb promotes proliferation and at the same time inhibits differentiation, however the early lethality of c-Myb deficient embryos precluded analysis of its role in adult hematopoiesis. Here we review insights derived from recently developed mouse models of c-Myb deficiency that are viable as adults. These studies reveal a complex array of functions for c-Myb in multiple hematopoietic cell types that will redefine our understanding of this crucial transcription factor.
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Affiliation(s)
- Kylie T Greig
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia.
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Alm-Kristiansen AH, Sæther T, Matre V, Gilfillan S, Dahle Ø, Gabrielsen OS. FLASH acts as a co-activator of the transcription factor c-Myb and localizes to active RNA polymerase II foci. Oncogene 2008; 27:4644-56. [DOI: 10.1038/onc.2008.105] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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