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Nagarajan S, Bedi U, Budida A, Xie W, Hamdan FHM, Mishra VK, Najafova Z, Alawi M, Indenbirken D, Knapp S, Chiang CM, Grundhoff A, Scheel CH, Kari V, Wegwitz F, Johnsen SA. Abstract 1982: BRD4-FOXO axis maintains differentiated mammary epithelial phenotype by regulating p63 and GRHL3 expression. Cancer Res 2016. [DOI: 10.1158/1538-7445.am2016-1982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Bromodomain-containing protein 4 (BRD4) is an important epigenetic reader which promotes gene transcription to modulate cell-specific functions and is under intensive investigation for its potential as an anti-tumor therapeutic target. However, the role of BRD4 in non-transformed cells remains unclear. Using RNA sequencing and chromatin immunoprecipitation-sequencing analyses in normal basal-like breast epithelial cells, we demonstrate that BRD4 is required for the expression of epithelial-specific genes and suppression of stem cell-like properties by binding to the distal regions of epithelial-related genes. Moreover, BRD4 occupancy correlates with enhancer activity and enhancer RNA (eRNA) transcription of these genes. Interestingly, we show that BRD4 perturbation regulates the expression of p63 and Grainy Head-like transcription factor-3, GRHL3, whose depletion partially mimics BRD4 inhibition and impairs a differentiated phenotype. By binding to the distal regions of p63 and GRHL3, BRD4 promotes RNA polymerase-II occupancy and thus affects eRNA transcription. Motif analyses on cell-specific BRD4 binding sites predict the involvement of FOXO transcription factors. Consistently, inhibition of EGFR-AKT signalling activates FOXO1 function and promotes the expression of p63 and GRHL3. Activation of Src kinase signaling decreases RNA polymerase-II occupancy on BRD4 target genes and enhancers. Altogether, these findings provide evidence that BRD4 promotes a differentiated epithelial phenotype in non-transformed mammary cells at least in part through the activation of p63 and GRHL3 expression by associating with FOXO factors.
Citation Format: Sankari Nagarajan, Upasana Bedi, Anusha Budida, Wanhua Xie, Feda Hisham Moh’d Hamdan, Vivek Kumar Mishra, Zeynab Najafova, Malik Alawi, Daniela Indenbirken, Stephan Knapp, Cheng-Ming Chiang, Adam Grundhoff, Christina H. Scheel, Vijayalakshmi Kari, Florian Wegwitz, Steven A. Johnsen. BRD4-FOXO axis maintains differentiated mammary epithelial phenotype by regulating p63 and GRHL3 expression. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1982.
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Affiliation(s)
- Sankari Nagarajan
- 1Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Germany; Cancer Research Centre UK, University of Cambridge, Cambridge, United Kingdom
| | - Upasana Bedi
- 2Institute for Molecular Oncology, University Medical Center Göttingen, Goettingen, Germany; Institute for Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anusha Budida
- 3Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Goettingen, Germany
| | - Wanhua Xie
- 3Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Goettingen, Germany
| | - Feda Hisham Moh’d Hamdan
- 3Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Goettingen, Germany
| | - Vivek Kumar Mishra
- 3Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Goettingen, Germany
| | - Zeynab Najafova
- 3Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Goettingen, Germany
| | - Malik Alawi
- 4Bioinformatics Core, University Medical Center Hamburg-Eppendorf; Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Daniela Indenbirken
- 5Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Stephan Knapp
- 6Structural Genomics Consortium and Target Discovery Institute, University of Oxford, Oxford, United Kingdom; Institute for Pharmaceutical Chemistry, Goethe Universität, Frankfurt, Germany
| | - Cheng-Ming Chiang
- 7University of Texas Southwestern Medical Center, Simmons Comprehensive Cancer Center, Dallas, TX
| | - Adam Grundhoff
- 5Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Christina H. Scheel
- 8Institute of Stem Cell Research, Helmholtz Center for Health and Environmental Research, Munich, Germany
| | - Vijayalakshmi Kari
- 3Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Goettingen, Germany
| | - Florian Wegwitz
- 3Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Goettingen, Germany
| | - Steven A. Johnsen
- 3Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Goettingen, Germany
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