title: Architecture of epigenetic reprogramming following Twist1-mediated epithelial-mesenchymal transition.
abstract: BACKGROUND
  Epithelial-mesenchymal transition (EMT) is known to impart metastasis and stemness characteristics in breast cancer. To characterize the epigenetic reprogramming following Twist1-induced EMT, we characterized the epigenetic and transcriptome landscapes using whole-genome transcriptome analysis by RNA-seq, DNA methylation by digital restriction enzyme analysis of methylation (DREAM) and histone modifications by CHIP-seq of H3K4me3 and H3K27me3 in immortalized human mammary epithelial cells relative to cells induced to undergo EMT by Twist1.
  
  
  RESULTS
  EMT is accompanied by focal hypermethylation and widespread global DNA hypomethylation, predominantly within transcriptionally repressed gene bodies. At the chromatin level, the number of gene promoters marked by H3K4me3 increases by more than one fifth; H3K27me3 undergoes dynamic genomic redistribution characterized by loss at half of gene promoters and overall reduction of peak size by almost half. This is paralleled by increased phosphorylation of EZH2 at serine 21. Among genes with highly altered mRNA expression, 23.1% switch between H3K4me3 and H3K27me3 marks, and those point to the master EMT targets and regulators CDH1, PDGFRα and ESRP1. Strikingly, Twist1 increases the number of bivalent genes by more than two fold. Inhibition of the H3K27 methyltransferases EZH2 and EZH1, which form part of the Polycomb repressive complex 2 (PRC2), blocks EMT and stemness properties.
  
  
  CONCLUSIONS
  Our findings demonstrate that the EMT program requires epigenetic remodeling by the Polycomb and Trithorax complexes leading to increased cellular plasticity. This suggests that inhibiting epigenetic remodeling and thus decrease plasticity will prevent EMT, and the associated breast cancer metastasis.
authors.forename: Gabriel G
authors.initials: GG
authors.lastname: Malouf
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Taube
authors.forename: Yue
authors.initials: Y
authors.lastname: Lu
authors.forename: Tapasree
authors.initials: T
authors.lastname: Roysarkar
authors.forename: Shoghag
authors.initials: S
authors.lastname: Panjarian
authors.forename: Marcos Rh
authors.initials: MR
authors.lastname: Estecio
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Jelinek
authors.forename: Jumpei
authors.initials: J
authors.lastname: Yamazaki
authors.forename: Noel J-M
authors.initials: NJ
authors.lastname: Raynal
authors.forename: Hai
authors.initials: H
authors.lastname: Long
authors.forename: Tomomitsu
authors.initials: T
authors.lastname: Tahara
authors.forename: Agata
authors.initials: A
authors.lastname: Tinnirello
authors.forename: Priyanka
authors.initials: P
authors.lastname: Ramachandran
authors.forename: Xiu-Ying
authors.initials: XY
authors.lastname: Zhang
authors.forename: Shoudan
authors.initials: S
authors.lastname: Liang
authors.forename: Sendurai A
authors.initials: SA
authors.lastname: Mani
authors.forename: Jean-Pierre J
authors.initials: JP
authors.lastname: Issa
mesh_terms: D002478:Cells, Cultured; D044127:Epigenesis, Genetic; D004847:Epithelial Cells / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D005786:Gene Expression Regulation; D015894:Genome, Human; D006657:Histones / Q000378:metabolism; D006801:Humans; D042361:Mammary Glands, Human / Q000166:cytology* / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D017423:Sequence Analysis, RNA / Q000379:methods; D051879:Twist-Related Protein 1 / Q000235:genetics*
chemical_list: D006657:Histones; D009687:Nuclear Proteins; C103173:TWIST1 protein, human; D051879:Twist-Related Protein 1