title: Chromatin modification of the trefoil factor 1 gene in human breast cancer cells by the Ras/mitogen-activated protein kinase pathway.
abstract: Histone H3 phosphorylation is a downstream response to activation of the Ras/mitogen-activated protein kinase (MAPK) pathway. This modification is thought to have a role in chromatin remodeling and in the initiation of gene transcription. In MCF-7 breast cancer cells, we observed that phosphorylated histone H3 (phospho-H3) at Ser(10) but not Ser(28) increased with phorbol ester (12-O-tetradecanoylphorbol-13-acetate, TPA) treatment. Although phosphorylated extracellular signal-regulated kinase 1/2 levels in these cells cultured under estradiol deplete and replete conditions displayed no change, a significant induction was observed after TPA treatment. Furthermore, whereas both estradiol and TPA increased trefoil factor 1 (TFF1) mRNA levels in these cells, only TPA-induced and not estradiol-induced TFF1 expression was inhibited by the H3 kinase mitogen and stress activated protein kinase (MSK) inhibitor H89 and MAPK kinase inhibitor UO126, showing the involvement of the Ras/MAPK following TPA induction. Mutation of the activator protein 1 (AP-1) binding site abrogated the TPA-induced transcriptional response of the luciferase reporter gene under the control of the TFF1 promoter, showing the requirement for the AP-1 site. In chromatin immunoprecipitation assays, estradiol treatment resulted in the association of the estrogen receptor-alpha (ERalpha) and acetylated H3 with the TFF1 promoter. The levels of phospho-H3 and MSK1 associated with the TFF1 promoter were moderately increased. In the presence of TPA, whereas ERalpha was not bound to the promoter, a strong association of acetylated and/or phospho-H3, MSK1, and c-Jun was observed. These results show that although both stimuli lead to TFF1 gene activation, estradiol and TPA exert their effects on TFF1 gene expression by different mechanisms.
authors.affiliation: Manitoba Institute of Cell Biology, Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Paula S
authors.initials: PS
authors.lastname: Espino
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.forename: Shihua
authors.initials: S
authors.lastname: He
authors.forename: Jenny
authors.initials: J
authors.lastname: Yu
authors.forename: James R
authors.initials: JR
authors.lastname: Davie
mesh_terms: D001665:Binding Sites; D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D045744:Cell Line, Tumor; D002843:Chromatin / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006657:Histones / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D010766:Phosphorylation / Q000187:drug effects; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis / Q000235:genetics*; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D002843:Chromatin; D006657:Histones; D016755:Proto-Oncogene Proteins c-jun; C051838:TFF1 protein, human; D018808:Transcription Factor AP-1; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins; D004958:Estradiol; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C116919:mitogen and stress-activated protein kinase 1; D018631:ras Proteins; D013755:Tetradecanoylphorbol Acetate