IL-6 plays a critical role in the synergistic induction of human serum amyloid A (SAA) gene when stimulated with proinflammatory cytokines as analyzed with an SAA isoform real-time quantitative RT-PCR assay system

Biochem Biophys Res Commun. 2004 Feb 6;314(2):363-9. doi: 10.1016/j.bbrc.2003.12.096.

Abstract

Serum amyloid A (SAA) is known to be a precursor of amyloid A (AA) protein in AA (secondary) amyloidosis and SAA1 to be mainly involved in AA amyloidosis. We established an SAA isoform real-time quantitative RT-PCR assay and found that beta-2 microglobulin is more stable as an internal control than GAPDH and beta-actin for our system. Either IL-6 and IL-1beta or IL-6 and TNFalpha, but not IL-1beta and TNFalpha, induced the synergistic induction of SAA1 and SAA2 genes. Anti-IL-6 receptor monoclonal antibody completely inhibited the synergistic induction of SAA1 and SAA2 during triple stimulation with IL-6, IL-1beta, and TNFalpha, but, IL-1 receptor antagonist or anti-TNFalpha monoclonal antibody was only partially inhibited in HepG2, Hep3B, and PLC/PRF/5 cells. Although the SAA1 promoter has no STAT3 consensus sequence, the JAK2 inhibitor-AG490 reduced SAA1 gene expression to 30%, suggesting the involvement of STAT3. We were able to demonstrate that IL-6 plays a critical role in the synergistic induction of human SAA gene when stimulated with proinflammatory cytokines.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Amyloid / chemistry
  • Antibodies, Monoclonal / chemistry
  • Antibodies, Monoclonal / metabolism
  • Blotting, Western
  • Cell Line
  • Cell Line, Tumor
  • Cytokines / biosynthesis*
  • DNA-Binding Proteins / metabolism
  • Dose-Response Relationship, Drug
  • Humans
  • Interleukin-1 / metabolism
  • Interleukin-6 / metabolism
  • Interleukin-6 / physiology*
  • Promoter Regions, Genetic
  • Protein Isoforms
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • STAT3 Transcription Factor
  • Serum Amyloid A Protein / chemistry
  • Serum Amyloid A Protein / genetics*
  • Time Factors
  • Trans-Activators / metabolism
  • Tumor Necrosis Factor-alpha / metabolism
  • Tyrphostins / pharmacology
  • beta 2-Microglobulin / metabolism

Substances

  • Actins
  • Amyloid
  • Antibodies, Monoclonal
  • Cytokines
  • DNA-Binding Proteins
  • Interleukin-1
  • Interleukin-6
  • Protein Isoforms
  • RNA, Messenger
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • Serum Amyloid A Protein
  • Trans-Activators
  • Tumor Necrosis Factor-alpha
  • Tyrphostins
  • alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide
  • beta 2-Microglobulin