title: Ectopic expression of the ErbB-3 binding protein ebp1 inhibits growth and induces differentiation of human breast cancer cell lines.
abstract: Ebp1, an ErbB-3 binding protein, translocates from the cytoplasm to the nucleus of human breast cancer cells after treatment with the ErbB-3 ligand, heregulin. The purpose of these studies was to examine the effects of ectopic expression of ebp1 on the biological properties of human ErbB-3-expressing breast carcinoma cell lines. Ectopic expression of ebp1 in ErbB-2, ErbB-3-expressing breast carcinoma cell lines resulted in inhibition of colony formation, a decreased proliferation rate, an accumulation of cells in the G2/M phase of the cell cycle, and suppression of growth in soft agar. Ectopic expression of ebp1 led to a more differentiated phenotype in AU565 breast cancer cells, as evidenced by increased expression of lipid droplets and of the milk protein casein. Basal phosphorylation of extracellular regulated kinases (Erks) 1 and 2, kinases activated by heregulin treatment, was also observed in ebp1 transfectants. The promoter for the intercellular adhesion molecule-1 gene, a heregulin-inducible gene, was constitutively activated in ebp1 transfectants as determined by reporter construct analysis. These data demonstrate that ectopic expression of the ErbB-3 binding protein Ebp1 inhibits proliferation and induces differentiation of ErbB-2, ErbB-3-expressing human breast carcinoma cell lines.
authors.affiliation: Molecular and Cellular Biology Program, University of Maryland, Baltimore, Maryland 21201, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Lessor
authors.forename: J Y
authors.initials: JY
authors.lastname: Yoo
authors.forename: X
authors.initials: X
authors.lastname: Xia
authors.forename: N
authors.initials: N
authors.lastname: Woodford
authors.forename: A W
authors.initials: AW
authors.lastname: Hamburger
mesh_terms: D001943:Breast Neoplasms; D002454:Cell Differentiation / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D005260:Female; D017930:Genes, Reporter; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D020890:Neuregulin-1 / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D020893:Receptor, ErbB-3 / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D020890:Neuregulin-1; D011994:Recombinant Proteins; D018799:Intercellular Adhesion Molecule-1; D020893:Receptor, ErbB-3; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases