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Drabsch Y, Hugo H, Zhang R, Dowhan DH, Miao YR, Gewirtz AM, Barry SC, Ramsay RG, Gonda TJ. Mechanism of and requirement for estrogen-regulated MYB expression in estrogen-receptor-positive breast cancer cells. Proc Natl Acad Sci U S A 2007; 104:13762-7. [PMID: 17690249 PMCID: PMC1959456 DOI: 10.1073/pnas.0700104104] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
MYB (the human ortholog of c-myb) is expressed in a high proportion of human breast tumors, and that expression correlates strongly with estrogen receptor (ER) positivity. This may reflect the fact that MYB is a target of estrogen/ER signaling. Because in many cases MYB expression appears to be regulated by transcriptional attenuation or pausing in the first intron, we first investigated whether this mechanism was involved in estrogen/ER modulation of MYB. We found that this was the case and that estrogen acted directly to relieve attenuation due to sequences within the first intron, specifically, a region potentially capable of forming a stem-loop structure in the transcript and an adjacent poly(dT) tract. Secondly, given the involvement of MYB in hematopoietic and colon tumors, we also asked whether MYB was required for the proliferation of breast cancer cells. We found that proliferation of ER(+) but not ER(-) breast cancer cell lines was inhibited when MYB expression was suppressed by using either antisense oligonucleotides or RNA interference. Our results show that MYB is an effector of estrogen/ER signaling and provide demonstration of a functional role of MYB in breast cancer.
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Affiliation(s)
- Yvette Drabsch
- *University of Queensland Diamantina Institute for Cancer, Immunology, and Metabolic Medicine, Brisbane, Queensland 4102, Australia
| | - Honor Hugo
- Peter MacCallum Cancer Centre, Melbourne, Victoria 3002, Australia
- Pathology Department, University of Melbourne, Victoria 3050, Australia
| | - Rui Zhang
- *University of Queensland Diamantina Institute for Cancer, Immunology, and Metabolic Medicine, Brisbane, Queensland 4102, Australia
| | - Dennis H. Dowhan
- *University of Queensland Diamantina Institute for Cancer, Immunology, and Metabolic Medicine, Brisbane, Queensland 4102, Australia
| | - Yu Rebecca Miao
- Peter MacCallum Cancer Centre, Melbourne, Victoria 3002, Australia
- Pathology Department, University of Melbourne, Victoria 3050, Australia
| | - Alan M. Gewirtz
- Division of Hematology/Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104; and
| | - Simon C. Barry
- Department of Paediatrics, University of Adelaide, South Australia 5006, Australia
| | - Robert G. Ramsay
- Peter MacCallum Cancer Centre, Melbourne, Victoria 3002, Australia
- Pathology Department, University of Melbourne, Victoria 3050, Australia
| | - Thomas J. Gonda
- *University of Queensland Diamantina Institute for Cancer, Immunology, and Metabolic Medicine, Brisbane, Queensland 4102, Australia
- **To whom correspondence should be addressed at:
University of Queensland Diamantina Institute for Cancer, Immunology, and Metabolic Medicine, Level 4, R Wing, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Queensland 4102, Australia. E-mail:
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Liu F, Lei W, O'Rourke JP, Ness SA. Oncogenic mutations cause dramatic, qualitative changes in the transcriptional activity of c-Myb. Oncogene 2006; 25:795-805. [PMID: 16205643 DOI: 10.1038/sj.onc.1209105] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The v-Myb oncoprotein encoded by Avian Myeloblastosis Virus is highly oncogenic, induces leukemias in chickens and mice and transforms immature hematopoietic cells in vitro. The v-Myb protein is a mutated and truncated version of c-Myb, a DNA-binding transcription factor expressed in many cell types that is essential for normal hematopoiesis. Previous studies suggested that two types of differences, DNA binding domain mutations and the deletion of a C-terminal negative regulatory domain were important for increasing the transforming activity of v-Myb. Here, we combined structure-function studies of the v-Myb and c-Myb proteins with unbiased microarray-based transcription assays to compare the transcriptional specificities of the two proteins. In human cells, the v-Myb and c-Myb proteins displayed strikingly different activities and regulated overlapping, but largely distinct sets of target genes. Each type of mutation that distinguished v-Myb from c-Myb, including the N- and C-terminal deletions, DNA binding domain changes and mutations in the transcriptional activation domain, affected different sets of target genes and contributed to the different activities of c-Myb and v-Myb. The results suggest that v-Myb is not just a de-repressed version of c-Myb. Instead, it is a distinct transcriptional regulator with a unique set of activities.
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Affiliation(s)
- F Liu
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131-0001, USA
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Bartley PA, Keough RA, Lutwyche JK, Gonda TJ. Regulation of the gene encoding glutathione S-transferase M1 (GSTM1) by the Myb oncoprotein. Oncogene 2003; 22:7570-5. [PMID: 14576818 DOI: 10.1038/sj.onc.1207136] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The identification of Myb 'target' genes will not only aid in the understanding of how overexpression of Myb, or expression of activated forms of Myb, leads to cellular transformation but will also shed light on its role in normal cells. Using a combination of an estrogen-regulated Myb-transformed cell line (ERMYB) and PCR-based subtractive hybridization, we have identified the gene (GSTM1) encoding the detoxification enzyme glutathione S-transferase M1 as being transcriptionally upregulated by Myb. Functional analysis of the GSTM1 promoter using reporter assays indicated that both the DNA binding and transactivation domains of Myb were required for transcriptional activation. Mutational ana-lysis of consensus Myb-binding sites (MBS) in the promoter and electrophoretic mobility gel shift analysis indicated that one of the three potential MBS can bind Myb protein, and is the primary site involved in the regulation of this promoter by Myb.
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Affiliation(s)
- Paul A Bartley
- Hanson Institute and Division of Human Immunology, Institute of Medical and Veterinary Science, Adelaide 5000, Australia
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Steffen B, Serve H, Berdel WE, Agrawal S, Linggi B, Büchner T, Hiebert SW, Müller-Tidow C. Specific protein redirection as a transcriptional therapy approach for t(8;21) leukemia. Proc Natl Acad Sci U S A 2003; 100:8448-53. [PMID: 12819347 PMCID: PMC166249 DOI: 10.1073/pnas.1330293100] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Important progress has been achieved in the knowledge about the pathogenesis of cancer. However, despite these advances, the therapeutic strategies are still limited. Leukemias are often characterized by specific balanced translocations, with the t(8;21) balanced translocation being the most frequent chromosomal aberration in acute myeloid leukemia (AML). This translocation produces the AML1-ETO fusion protein, which binds to AML1 target promoter sequences. Transcriptional repression of AML1-dependent genes by AML1-ETO and associated corepressors represents the pathogenetic mechanisms of t(8;21). Here, we show that targeting of AML1-ETO to essential, MYB-dependent gene promoters induces t(8;21)-restricted cell death. We constructed a chimeric protein that contained the MYB DNA-binding domain and the AML1-binding domain of myeloid Elf-1-like factor (MEF). This protein associated with AML1-ETO and directed the complex to MYB-responsive promoters in vitro and in vivo. In the presence of AML1-ETO, the chimeric protein repressed the activity of MYB-responsive promoters, rapidly induced apoptosis, and specifically inhibited colony growth. All these effects occurred only in AML1-ETO-positive cells, whereas no adverse effects were observed in cells not expressing AML1-ETO. Taken together, this study demonstrates that redirection of oncogenic proteins can be used as a strategy to dramatically influence their cellular effects, with the ultimate goal to design highly specific therapies for cancer.
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MESH Headings
- Acute Disease
- Animals
- Apoptosis/physiology
- Binding Sites
- COS Cells
- Chromosomes, Human, Pair 21/genetics
- Chromosomes, Human, Pair 21/ultrastructure
- Chromosomes, Human, Pair 8/genetics
- Chromosomes, Human, Pair 8/ultrastructure
- Core Binding Factor Alpha 2 Subunit
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Genes, myb
- Humans
- Leukemia, Myeloid/genetics
- Leukemia, Myeloid/pathology
- Leukemia, Myeloid/therapy
- Macromolecular Substances
- Mice
- Neoplasm Proteins/genetics
- Neoplasm Proteins/physiology
- Oncogene Proteins/genetics
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/physiology
- Promoter Regions, Genetic/genetics
- Protein Binding
- Protein Structure, Tertiary
- Proto-Oncogene Proteins c-kit
- Proto-Oncogene Proteins c-myb/chemistry
- Proto-Oncogene Proteins c-myb/physiology
- RUNX1 Translocation Partner 1 Protein
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/physiology
- Substrate Specificity
- Transcription Factors/chemistry
- Transcription Factors/genetics
- Transcription Factors/physiology
- Transcription, Genetic
- Translocation, Genetic
- Tumor Cells, Cultured
- Tumor Stem Cell Assay
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Affiliation(s)
- Björn Steffen
- Department of Medicine, Hematology/Oncology,
University of Münster, 48129 Münster, Germany; and
Department of Biochemistry, Vanderbilt
University School of Medicine, Nashville, TN 37232
| | - Hubert Serve
- Department of Medicine, Hematology/Oncology,
University of Münster, 48129 Münster, Germany; and
Department of Biochemistry, Vanderbilt
University School of Medicine, Nashville, TN 37232
- To whom correspondence should be addressed at: Department of Medicine,
Hematology/Oncology, University of Münster, Albert-Schweitzer-Strasse 33,
48129 Münster, Germany. E-mail:
| | - Wolfgang E. Berdel
- Department of Medicine, Hematology/Oncology,
University of Münster, 48129 Münster, Germany; and
Department of Biochemistry, Vanderbilt
University School of Medicine, Nashville, TN 37232
| | - Shuchi Agrawal
- Department of Medicine, Hematology/Oncology,
University of Münster, 48129 Münster, Germany; and
Department of Biochemistry, Vanderbilt
University School of Medicine, Nashville, TN 37232
| | - Bryan Linggi
- Department of Medicine, Hematology/Oncology,
University of Münster, 48129 Münster, Germany; and
Department of Biochemistry, Vanderbilt
University School of Medicine, Nashville, TN 37232
| | - Thomas Büchner
- Department of Medicine, Hematology/Oncology,
University of Münster, 48129 Münster, Germany; and
Department of Biochemistry, Vanderbilt
University School of Medicine, Nashville, TN 37232
| | - Scott W. Hiebert
- Department of Medicine, Hematology/Oncology,
University of Münster, 48129 Münster, Germany; and
Department of Biochemistry, Vanderbilt
University School of Medicine, Nashville, TN 37232
| | - Carsten Müller-Tidow
- Department of Medicine, Hematology/Oncology,
University of Münster, 48129 Münster, Germany; and
Department of Biochemistry, Vanderbilt
University School of Medicine, Nashville, TN 37232
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The aberrant fusion proteins PML-RARα and PLZF-RARα contribute to the overexpression of cyclin A1 in acute promyelocytic leukemia. Blood 2000. [DOI: 10.1182/blood.v96.12.3894.h8003894_3894_3899] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cyclin A1 is a newly discovered cyclin that is overexpressed in certain myeloid leukemias. Previously, the authors found that the frequency of cyclin A1 overexpression is especially high in acute promyelocytic leukemia (APL). In this study, the authors investigated the mechanism of cyclin A1 overexpression in APL cells and showed that the APL-associated aberrant fusion proteins (PML–retinoic acid receptor alpha [PML-RARα] or PLZF-RARα) caused the increased levels of cyclin A1 in these cells. The ectopic expression of either PML-RARα or PLZF-RARα in U937 cells, a non-APL myeloid cell line, led to a dramatic increase of cyclin A1 messenger RNA and protein. This elevation of cyclin A1 was reversed by treatment with all-trans retinoic acid (ATRA) in cells expressing PML-RARα but not PLZF-RARα. ATRA also greatly reduced the high levels of cyclin A1 in the APL cell lines NB4 and UF-1. No effect of ATRA on cyclin A1 levels was found in the ATRA-resistant NB4-R2 cells. Further studies using ligands selective for various retinoic acid receptors suggested that cyclin A1 expression is negatively regulated by activated RARα. Reporter assays showed that PML-RARα led to activation of the cyclin A1 promoter. Addition of ATRA inhibited PML-RARα–induced cyclin A1 promoter activity. Taken together, our data suggest that PML-RARα and PLZF-RARα cause the high-level expression of cyclin A1 seen in acute promyelocytic leukemia.
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