title: Trp63 is regulated by STAT5 in mammary tissue and subject to differentiation in cancer.
abstract: Transformation-related protein 63 (Trp63), the predominant member of the Trp53 family, contributes to epithelial differentiation and is expressed in breast neoplasia. Trp63 features two distinct promoters yielding specific mRNAs encoding two major TRP63 isoforms, a transactivating transcription factor and a dominant negative isoform. Specific TRP63 isoforms are linked to cell cycle arrest, apoptosis, survival, and epithelial mesenchymal transition (EMT). Although TRP63 overexpression in cultured cells is used to elucidate functions, little is known about Trp63 regulation in normal and cancerous mammary tissues. This study used ChIP-seq to interrogate transcription factor binding and histone modifications of the Trp63 locus in mammary tissue and RNA-seq and immunohistochemistry to gauge gene expression. H3K4me2 and H3K4me3 marks coincided only with the proximal promoter, supporting RNA-seq data showing the predominance of the dominant negative isoform. STAT5 bound specifically to the Trp63 proximal promoter and Trp63 mRNA levels were elevated upon deleting Stat5 from mammary tissue, suggesting its role as a negative regulator. The dominant negative TRP63 isoform was localized to nuclei of basal mammary epithelial cells throughout reproductive cycles and retained in a majority of the triple-negative cancers generated from loss of full-length Brca1. Increased expression of dominant negative isoforms was correlated with developmental windows of increased progesterone receptor binding to the proximal Trp63 promoter and decreased expression during lactation was correlated with STAT5 binding to the same region. TRP63 is present in the majority of triple-negative cancers resulting from loss of Brca1 but diminished in less differentiated cancer subtypes and in cancer cells undergoing EMT.
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, 3970 Reservoir Road NW, Research Building, Room 520A, Washington, District of Columbia 20057, USA Laboratory of Genetics and Physiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 8 Center Drive, Bethesda, Maryland 20892-0822, USA Department of Microbiology, Dankook University, Cheonan 330-714, Republic of Korea Department Pharmazie, Ludwig-Maximilians-Universität München, München, Germany College of Medical Sciences, King Khalid University, Abha, Saudi Arabia Departments of Pathology Medicine, Lombardi Comprehensive Cancer Center, Georgetown University, 3970 Reservoir Road NW, Research Building, Room 520A, Washington, District of Columbia 20057 USA.
authors.forename: Shahin
authors.initials: S
authors.lastname: Assefnia
authors.forename: Keunsoo
authors.initials: K
authors.lastname: Kang
authors.forename: Svenja
authors.initials: S
authors.lastname: Groeneveld
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamaji
authors.forename: Sarah
authors.initials: S
authors.lastname: Dabydeen
authors.forename: Ahmad
authors.initials: A
authors.lastname: Alamri
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Liu
authors.forename: Lothar
authors.initials: L
authors.lastname: Hennighausen
authors.forename: Priscilla A
authors.initials: PA
authors.lastname: Furth
mesh_terms: D000818:Animals; D019313:BRCA1 Protein / Q000502:physiology; D015153:Blotting, Western; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D059014:High-Throughput Nucleotide Sequencing; D006657:Histones / Q000378:metabolism; D007124:Immunoenzyme Techniques; D008321:Mammary Glands, Animal / Q000254:growth & development* / Q000378:metabolism*; D015674:Mammary Neoplasms, Animal / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010750:Phosphoproteins / Q000502:physiology*; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012098:Reproduction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050799:STAT5 Transcription Factor / Q000378:metabolism*; D015534:Trans-Activators / Q000502:physiology*
chemical_list: D019313:BRCA1 Protein; D006657:Histones; D010750:Phosphoproteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; C486419:Trp63 protein, mouse
keywords: gene regulation; mammary gland; molecular genetics; neoplasia; oncogene