title: BRD4 promotes p63 and GRHL3 expression downstream of FOXO in mammary epithelial cells.
abstract: Bromodomain-containing protein 4 (BRD4) is a member of the bromo- and extraterminal (BET) domain-containing family of epigenetic readers which is under intensive investigation as a target for anti-tumor therapy. BRD4 plays a central role in promoting the expression of select subsets of genes including many driven by oncogenic transcription factors and signaling pathways. However, the role of BRD4 and the effects of BET inhibitors in non-transformed cells remain mostly unclear. We demonstrate that BRD4 is required for the maintenance of a basal epithelial phenotype by regulating the expression of epithelial-specific genes including TP63 and Grainy Head-like transcription factor-3 (GRHL3) in non-transformed basal-like mammary epithelial cells. Moreover, BRD4 occupancy correlates with enhancer activity and enhancer RNA (eRNA) transcription. Motif analyses of cell context-specific BRD4-enriched regions predicted the involvement of FOXO transcription factors. Consistently, activation of FOXO1 function via inhibition of EGFR-AKT signaling promoted the expression of TP63 and GRHL3. Moreover, activation of Src kinase signaling and FOXO1 inhibition decreased the expression of FOXO/BRD4 target genes. Together, our findings support a function for BRD4 in promoting basal mammary cell epithelial differentiation, at least in part, by regulating FOXO factor function on enhancers to activate TP63 and GRHL3 expression.
authors.affiliation: Department of General, Visceral and Pediatric Surgery, Göttingen Center for Molecular Biosciences, University Medical Center Göttingen, 37077 Göttingen, Germany.
authors.forename: Sankari
authors.initials: S
authors.lastname: Nagarajan
authors.affiliation: Institute of Molecular Oncology, University Medical Center Göttingen, 37077 Göttingen, Germany.|Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
authors.forename: Upasana
authors.initials: U
authors.lastname: Bedi
authors.affiliation: Department of General, Visceral and Pediatric Surgery, Göttingen Center for Molecular Biosciences, University Medical Center Göttingen, 37077 Göttingen, Germany.
authors.forename: Anusha
authors.initials: A
authors.lastname: Budida
authors.affiliation: Department of General, Visceral and Pediatric Surgery, Göttingen Center for Molecular Biosciences, University Medical Center Göttingen, 37077 Göttingen, Germany.
authors.forename: Feda H
authors.initials: FH
authors.lastname: Hamdan
authors.affiliation: Department of General, Visceral and Pediatric Surgery, Göttingen Center for Molecular Biosciences, University Medical Center Göttingen, 37077 Göttingen, Germany.
authors.forename: Vivek Kumar
authors.initials: VK
authors.lastname: Mishra
authors.affiliation: Department of General, Visceral and Pediatric Surgery, Göttingen Center for Molecular Biosciences, University Medical Center Göttingen, 37077 Göttingen, Germany.
authors.forename: Zeynab
authors.initials: Z
authors.lastname: Najafova
authors.affiliation: Department of General, Visceral and Pediatric Surgery, Göttingen Center for Molecular Biosciences, University Medical Center Göttingen, 37077 Göttingen, Germany.
authors.forename: Wanhua
authors.initials: W
authors.lastname: Xie
authors.affiliation: Bioinformatics Core, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany.|Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, 20251 Hamburg, Germany.
authors.forename: Malik
authors.initials: M
authors.lastname: Alawi
authors.affiliation: Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, 20251 Hamburg, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Indenbirken
authors.affiliation: Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK.|Target Discovery Institute, University of Oxford, Oxford OX3 7FZ, UK.|Institute for Pharmaceutical Chemistry, Goethe University Frankfurt 60323, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Knapp
authors.affiliation: University of Texas Southwestern Medical Center, Simmons Comprehensive Cancer Center, Dallas, TX 75235, USA.
authors.forename: Cheng-Ming
authors.initials: CM
authors.lastname: Chiang
authors.affiliation: Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, 20251 Hamburg, Germany.
authors.forename: Adam
authors.initials: A
authors.lastname: Grundhoff
authors.affiliation: Department of General, Visceral and Pediatric Surgery, Göttingen Center for Molecular Biosciences, University Medical Center Göttingen, 37077 Göttingen, Germany.
authors.forename: Vijayalakshmi
authors.initials: V
authors.lastname: Kari
authors.affiliation: Institute of Stem Cell Research, Helmholtz Center for Health and Environmental Research Munich, 85764 Neuherberg, Germany.
authors.forename: Christina H
authors.initials: CH
authors.lastname: Scheel
authors.affiliation: Department of General, Visceral and Pediatric Surgery, Göttingen Center for Molecular Biosciences, University Medical Center Göttingen, 37077 Göttingen, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Wegwitz
authors.affiliation: Department of General, Visceral and Pediatric Surgery, Göttingen Center for Molecular Biosciences, University Medical Center Göttingen, 37077 Göttingen, Germany.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Johnsen
mesh_terms: D001940:Breast / Q000166:cytology / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D004847:Epithelial Cells / Q000378:metabolism*; D051858:Forkhead Transcription Factors / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis / Q000235:genetics*; D000092468:Bromodomain Containing Proteins
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D051858:Forkhead Transcription Factors; D009687:Nuclear Proteins; D051057:Proto-Oncogene Proteins c-akt; D016392:Proto-Oncogene Proteins pp60(c-src); D012319:RNA Polymerase II; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C441289:BRD4 protein, human; D000092468:Bromodomain Containing Proteins; C473143:GRHL3 protein, human; C115051:TP63 protein, human