title: Oncogenic RAS alters the global and gene-specific histone modification pattern during epithelial-mesenchymal transition in colorectal carcinoma cells.
abstract: The presence of different forms of histone covalent modifications, such as phosphorylation, acetylation and methylation in localized promoter regions are markers for chromatin packing and transcription. Activation of RAS signalling pathways through oncogenic RAS mutations is a hallmark of colorectal cancer. Overexpression of Harvey-Ras oncogene induces epithelial-mesenchymal transition (EMT) in Caco-2 cells. We focused on the role of epigenetic modifications of histone H3 and its dependence on RAS signal transduction pathways and oncogenic transformation. Using cell lines stably overexpressing oncogenic Harvey-RAS with EMT phenotype, we studied the acquired changes in the H3 histone modification patterns. Two genes show inverse protein expression patterns after Ha-RAS overexpression: Cyclin D1, a cell cycle-related gene, and the EMT marker-gene E-cadherin. We report that these two genes demonstrate matching inverse histone repression patterns on their promoter, while histone markers associated with an active state of genes were affected by the RAS-activated signalling pathway MEK-ERK-MSK1. Furthermore, we show that though the level of methyltransferases enzymes was increased, the status of H3 three-methylation at lysine 27 (H3K27me(3)), associated with gene repression on the promoter of Cyclin D1, was lower. Together, these results suggest that histone covalent modifications can be affected by oncogenic RAS pathways to regulate the expression of target genes like Cyclin D1 or E-cadherin and that the dynamic balance of opposing histone-modifying enzymes is critical for the regulation of cell proliferation.
authors.affiliation: Laboratory of Signal Mediated Gene Expression, Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, Athens, Greece.
authors.forename: Ignacio Mazón
authors.initials: IM
authors.lastname: Peláez
authors.forename: Margarita
authors.initials: M
authors.lastname: Kalogeropoulou
authors.forename: Angelo
authors.initials: A
authors.lastname: Ferraro
authors.forename: Angeliki
authors.initials: A
authors.lastname: Voulgari
authors.forename: Tibor
authors.initials: T
authors.lastname: Pankotai
authors.forename: Imre
authors.initials: I
authors.lastname: Boros
authors.forename: Alexander
authors.initials: A
authors.lastname: Pintzas
mesh_terms: D018938:Caco-2 Cells; D015820:Cadherins / Q000096:biosynthesis / Q000235:genetics; D002471:Cell Transformation, Neoplastic; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D019938:Cyclin D1 / Q000096:biosynthesis / Q000235:genetics; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006657:Histones / Q000378:metabolism*; D006801:Humans; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000378:metabolism* / Q000473:pathology; D011499:Protein Processing, Post-Translational / Q000235:genetics; D015398:Signal Transduction; D019076:Transgenes; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D015820:Cadherins; D006657:Histones; D019938:Cyclin D1; D020930:MAP Kinase Kinase Kinases; D018631:ras Proteins