title: Involvement of NF-kappaB in the regulation of S100A6 gene expression in human hepatoblastoma cell line HepG2.
abstract: S100A6 (calcyclin) is an acidic calcium binding protein with two EF-hand motifs and overexpressed in several tumors including intrahepatic carcinoma. TNFalpha, a strong NF-kappaB activator required for hepatocyte proliferation during liver regeneration, triggered the expression of S100A6 mRNA in human hepatoblastoma cell line HepG2. Transient expression of NF-kappaB (p65) increased S100A6 promoter activity and expression of inhibitor of NF-kappaB (IkappaBalpha) decreased TNFalpha-induced S100A6 promoter activity. To confirm the involvement of NF-kappaB in S100A6 promoter activation, we analyzed serially deleted promoter constructs of the S100A6 gene by luciferase reporter assay and found a NF-kappaB-responsive DNA fragment at the position between -584 and -361. Electrophoretic mobility shift assays showed that TNFalpha induced p65 binding to a potential NF-kappaB binding site at -460/-451. Furthermore, treatment of cells with CAPE (caffeic acid phenethyl ester), a specific NF-kappaB (p65) inhibitor, decreased NF-kappaB binding and promoter activity. These results suggest that NF-kappaB transcription factor contributes to the activation of S100A6 gene expression in response to TNFalpha in HepG2 cells.
authors.affiliation: Cell Biology Laboratory, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.
authors.forename: Joung Hyuck
authors.initials: JH
authors.lastname: Joo
authors.forename: Jae Wha
authors.initials: JW
authors.lastname: Kim
authors.forename: Younghee
authors.initials: Y
authors.lastname: Lee
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Yoon
authors.forename: Joo Heon
authors.initials: JH
authors.lastname: Kim
authors.forename: Sang-Gi
authors.initials: SG
authors.lastname: Paik
authors.forename: In Seong
authors.initials: IS
authors.lastname: Choe
mesh_terms: D001665:Binding Sites; D018797:Cell Cycle Proteins; D015972:Gene Expression Regulation, Neoplastic; D018197:Hepatoblastoma / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D000075383:S100 Calcium Binding Protein A6; D009418:S100 Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D000075383:S100 Calcium Binding Protein A6; D009418:S100 Proteins; D014409:Tumor Necrosis Factor-alpha; C055351:S100A6 protein, human