title: Fra-1/AP-1 induces EMT in mammary epithelial cells by modulating Zeb1/2 and TGFβ expression.
abstract: Epithelial-to-mesenchymal transition (EMT) is essential for embryonic morphogenesis and wound healing and critical for tumour cell invasion and dissemination. The AP-1 transcription factor Fra-1 has been implicated in tumorigenesis and in tumour-associated EMT in human breast cancer. We observed a significant inverse correlation between Fra-1 mRNA expression and distant-metastasis-free survival in a large cohort of breast cancer patients derived from multiple array data sets. This unique correlation among Fos genes prompted us to assess the evolutionary conservation between Fra-1 functions in EMT of human and mouse cells. Ectopic expression of Fra-1 in fully polarized, non-tumourigenic, mouse mammary epithelial EpH4 cells induced a mesenchymal phenotype, characterized by a loss of epithelial and gain of mesenchymal markers. Proliferation, motility and invasiveness were also increased in the resulting EpFra1 cells, and the cells were tumourigenic and efficiently colonized the lung upon transplantation. Molecular analyses revealed increased expression of Tgfβ1 and the EMT-inducing transcription factors Zeb1, Zeb2 and Slug. Mechanistically, Fra-1 binds to the tgfb1 and zeb2 promoters and to an evolutionarily conserved region in the first intron of zeb1. Furthermore, increased activity of a zeb2 promoter reporter was detected in EpFra1 cells and shown to depend on AP-1-binding sites. Inhibiting TGFβ signalling in EpFra1 cells moderately increased the expression of epithelial markers, whereas silencing of zeb1 or zeb2 restored the epithelial phenotype and decreased migration in vitro and tumorigenesis in vivo. Thus Fra-1 induces changes in the expression of genes encoding EMT-related transcription factors leading to the acquisition of mesenchymal, invasive and tumorigenic capacities by epithelial cells. This study defines a novel function of Fra-1/AP-1 in modulating tgfb1, zeb1 and zeb2 expression through direct binding to genomic regulatory regions, which establishes a basis for future in vivo genetic manipulations and preclinical studies using mouse models.
authors.affiliation: Genes, Development and Disease Group, F-BBVA Cancer Cell Biology Programme, National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Bakiri
authors.affiliation: Institute for Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Macho-Maschler
authors.affiliation: Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: I
authors.initials: I
authors.lastname: Custic
authors.affiliation: Institute for Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Niemiec
authors.affiliation: Genes, Development and Disease Group, F-BBVA Cancer Cell Biology Programme, National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Guío-Carrión
authors.affiliation: Genes, Development and Disease Group, F-BBVA Cancer Cell Biology Programme, National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: S C
authors.initials: SC
authors.lastname: Hasenfuss
authors.affiliation: IMC University of Applied Sciences, Krems, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Eger
authors.affiliation: Institute for Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Müller
authors.affiliation: 1] Institute for Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria [2] Research Institute of Molecular Pathology, Vienna, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Beug
authors.affiliation: Genes, Development and Disease Group, F-BBVA Cancer Cell Biology Programme, National Cancer Research Centre (CNIO), Madrid, Spain.
authors.forename: E F
authors.initials: EF
authors.lastname: Wagner
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology; D015820:Cadherins / Q000235:genetics; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D042361:Mammary Glands, Human / Q000166:cytology; D051379:Mice; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D000074165:Zinc Finger E-box Binding Homeobox 2; D000071799:Zinc Finger E-box-Binding Homeobox 1; D000099169:Fos-Related Antigen 1
chemical_list: D015820:Cadherins; D018398:Homeodomain Proteins; D016760:Proto-Oncogene Proteins c-fos; D012097:Repressor Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D000074165:Zinc Finger E-box Binding Homeobox 2; D000071799:Zinc Finger E-box-Binding Homeobox 1; D000099169:Fos-Related Antigen 1; C486307:ZEB1 protein, human; C492363:ZEB2 protein, human