RRC ID 42922
Author Tomizawa M, Saisho H.
Title Insulin-like growth factor (IGF)-II regulates CCAAT/enhancer binding protein alpha expression via phosphatidyl-inositol 3 kinase in human hepatoblastoma cell lines.
Journal J Cell Biochem
Abstract To reveal growth factor and its signal pathway to CCAAT/enhancer binding protein alpha (C/EBPalpha) in hepatocyte differentiation, we used Huh-6 and HepG2, human hepatoblastoma (HBL) cell lines that maintain the expression of genes in hepatoblasts and remain at that stage of differentiation. Insulin-like growth factor (IGF)-II, hepatocyte growth factor (HGF), and dexamethasone (Dex) stimulated HBL cells for Northern blot analysis. Bromodeoxyuridine (BrdU) up-take assay and Western blot analysis on albumin was performed to unveil proliferation and differentiation activity of IGF-II. C/EBPalpha and phosphorylation of Akt were analyzed by Western blot analysis. LY294002 and wortmannin, specific inhibitors of PI3 kinase, and PD98059, a specific inhibitor of mitogen-activated protein (MAP) kinase, were used to examine the signaling pathway of C/EBPalpha upregulated by IGF-II. Luciferase assay was performed to study the promoter activity of C/EBPalpha. Actinomycin D was used to analyze half-life of C/EBPalpha mRNA. IGF-II up-regualted C/EBPalpha by Northern blot and Western blot while HGF and Dex did not by Northern blot. IGF-II promoted proliferation and differentiation by BrdU up-take assay and Western blot analysis on albumin. Akt phosphorylated by IGF-II, suggested that phosphatidyl-inositol (PI) 3 kinase mediated the signaling pathway of IGF-II. LY294002 and wortmannin suppressed expression of C/EBPalpha. IGF-II activated the promoter activity and prolonged half-life of mRNA, suggesting that IGF-II activated promoter and stabilized mRNA. LY294002 and wortmannin suppressed the promoter activity of C/EBPalpha while PD98059 did not, suggesting that activation of the promoter was mediated by PI3 kinase.
Volume 102(1)
Pages 161-70
Published 2007-9-1
DOI 10.1002/jcb.21293
PMID 17372916
MeSH Androstadienes / pharmacology CCAAT-Binding Factor / biosynthesis CCAAT-Binding Factor / genetics* Cell Line, Tumor Cell Proliferation / drug effects Chromones / pharmacology Enzyme Inhibitors / pharmacology Hepatoblastoma Hepatocytes / metabolism* Humans Insulin-Like Growth Factor II / pharmacology* Liver Neoplasms Morpholines / pharmacology Phosphatidylinositol 3-Kinases / metabolism* Phosphoinositide-3 Kinase Inhibitors Promoter Regions, Genetic RNA Stability Up-Regulation* Wortmannin
IF 3.448
Times Cited 8
Human and Animal Cells