title: Mechanistic study on growth suppression and apoptosis induction by targeting hepatoma-derived growth factor in human hepatocellular carcinoma HepG2 cells.
abstract: Hepatoma-derived growth factor (HDGF) is frequently overexpressed in human cancer. The growth factor was previously demonstrated to be a survival factor as knock-down of HDGF suppresses the growth and induces apoptosis in human cancer cells through the Bad-mediated intrinsic apoptotic pathway. However, inactivation of Bad cannot completely repress the apoptosis induced upon HDGF knock-down, indicating the presence of other unidentified pathways. In the present study, HDGF knock-down was shown to trigger the Fas-mediated extrinsic apoptotic pathway in human hepatocellular carcinoma HepG2 cells through NF-kappaB signaling pathway. Increases in Fas expression and fas promoter activity were detected upon HDGF knock-down by Western blot analysis and luciferase reporter assay. Knock-down of fas inhibited HDGF knock-down effect on apoptosis induction and growth suppression as revealed by annexin V binding assay and soft agar assay. Down-regulation of IkappaBalpha was also observed upon HDGF knock-down. Overexpression of IkappaBalpha by transient transfection or inhibition of NF-kappaB by BAY11-7082 suppressed HDGF knock-down effect on fas promoter activation, Fas up-regulation, apoptosis induction and growth suppression. Furthermore, the interaction of Fas-mediated extrinsic and Bad-mediated intrinsic apoptotic pathways was demonstrated as a stronger inhibition on apoptosis induction and growth suppression upon HDGF knock-down was observed when both pathways were inactivated. The results therefore suggested that, through both intrinsic and extrinsic apoptotic pathways, HDGF may function as a survival factor and be a potential target for cancer therapy.
authors.affiliation: Department of Biochemistry, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
authors.forename: Tsun Yee
authors.initials: TY
authors.lastname: Tsang
authors.forename: Wan Yee
authors.initials: WY
authors.lastname: Tang
authors.forename: Wing Pui
authors.initials: WP
authors.lastname: Tsang
authors.forename: Ngai Na
authors.initials: NN
authors.lastname: Co
authors.forename: Siu Kai
authors.initials: SK
authors.lastname: Kong
authors.forename: Tim Tak
authors.initials: TT
authors.lastname: Kwok
mesh_terms: D017304:Annexin A5 / Q000032:analysis / Q000378:metabolism; D017209:Apoptosis; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D053938:DNA Fragmentation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D017930:Genes, Reporter; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D049410:Luciferases, Renilla / Q000378:metabolism; D008954:Models, Biological; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D013450:Sulfones / Q000494:pharmacology; D014162:Transfection; D051025:bcl-Associated Death Protein / Q000378:metabolism; D019014:fas Receptor / Q000096:biosynthesis
chemical_list: C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; D017304:Annexin A5; D036341:Intercellular Signaling Peptides and Proteins; D016328:NF-kappa B; D009570:Nitriles; D016376:Oligonucleotides, Antisense; D034741:RNA, Small Interfering; D013450:Sulfones; D051025:bcl-Associated Death Protein; D019014:fas Receptor; C051610:hepatoma-derived growth factor; D049410:Luciferases, Renilla