Involvement of NF-kappaB in the regulation of S100A6 gene expression in human hepatoblastoma cell line HepG2

Biochem Biophys Res Commun. 2003 Jul 25;307(2):274-80. doi: 10.1016/s0006-291x(03)01199-9.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Cell Cycle Proteins*
  • Gene Expression Regulation, Neoplastic*
  • Hepatoblastoma / genetics
  • Hepatoblastoma / metabolism*
  • Humans
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism*
  • NF-kappa B / metabolism*
  • Promoter Regions, Genetic
  • RNA, Messenger / metabolism
  • S100 Calcium Binding Protein A6
  • S100 Proteins / genetics*
  • S100 Proteins / metabolism
  • Signal Transduction / physiology
  • Transcriptional Activation
  • Tumor Cells, Cultured
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Cell Cycle Proteins
  • NF-kappa B
  • RNA, Messenger
  • S100 Calcium Binding Protein A6
  • S100 Proteins
  • Tumor Necrosis Factor-alpha
  • S100A6 protein, human