title: Intersection of FOXO- and RUNX1-mediated gene expression programs in single breast epithelial cells during morphogenesis and tumor progression.
abstract: Gene expression networks are complicated by the assortment of regulatory factors that bind DNA and modulate transcription combinatorially. Single-cell measurements can reveal biological mechanisms hidden by population averages, but their value has not been fully explored in the context of mRNA regulation. Here, we adapted a single-cell expression profiling technique to examine the gene expression program downstream of Forkhead box O (FOXO) transcription factors during 3D breast epithelial acinar morphogenesis. By analyzing patterns of mRNA fluctuations among individual matrix-attached epithelial cells, we found that a subset of FOXO target genes was jointly regulated by the transcription factor Runt-related transcription factor 1 (RUNX1). Knockdown of RUNX1 causes hyperproliferation and abnormal morphogenesis, both of which require normal FOXO function. Down-regulating RUNX1 and FOXOs simultaneously causes widespread oxidative stress, which arrests proliferation and restores normal acinar morphology. In hormone-negative breast cancers lacking human epidermal growth factor receptor 2 (HER2) amplification, we find that RUNX1 down-regulation is strongly associated with up-regulation of FOXO1, which may be required to support growth of RUNX1-negative tumors. The coordinate function of these two tumor suppressors may provide a failsafe mechanism that inhibits cancer progression.
authors.affiliation: Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Lixin
authors.initials: L
authors.lastname: Wang
authors.forename: Joan S
authors.initials: JS
authors.lastname: Brugge
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Janes
mesh_terms: D061354:Acinar Cells / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000503:physiopathology; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D019295:Computational Biology; D050676:Core Binding Factor Alpha 2 Subunit / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics / Q000502:physiology*; D053263:Gene Regulatory Networks / Q000235:genetics / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D017404:In Situ Hybridization, Fluorescence; D016086:Lentivirus; D009024:Morphogenesis; D034622:RNA Interference; D049490:Systems Biology
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; C493728:RUNX1 protein, human