Suppression of NF-kappaB activity by sulfasalazine is mediated by direct inhibition of IkappaB kinases alpha and beta

Gastroenterology. 2000 Nov;119(5):1209-18. doi: 10.1053/gast.2000.19458.

Abstract

Background & aims: Activation of NF-kappaB/Rel has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Various drugs used in the treatment of IBD, such as glucocorticoids, 5-aminosalicylic acid, and sulfasalazine, interfere with NF-kappaB/Rel signaling. The aim of this study was to define the molecular mechanism by which sulfasalazine inhibits NF-kappaB activation.

Methods: The effects of sulfasalazine and its moieties on NF-kappaB signaling were evaluated using electromobility shift, transfection, and immune complex kinase assays. The direct effect of sulfasalazine on IkappaB kinase (IKK) activity was investigated using purified recombinant IKK-alpha and -beta proteins.

Results: NF-kappaB/Rel activity induced by tumor necrosis factor alpha, 12-O-tetradecanoylphorbol-13-acetate, or overexpression of NF-kappaB-inducing kinase, IKK-alpha, IKK-beta, or constitutively active IKK-alpha and IKK-beta mutants was inhibited dose dependently by sulfasalazine. Sulfasalazine inhibited tumor necrosis factor alpha-induced activation of endogenous IKK in Jurkat T cells and SW620 colon cells, as well as the catalytic activity of purified IKK-alpha and IKK-beta in vitro. In contrast, the moieties of sulfasalazine, 5-aminosalicylic acid, and sulfapyridine or 4-aminosalicylic acid had no effect. Activation of extracellular signal-related kinase (ERK) 1 and 2, c-Jun-N-terminal kinase (JNK) 1, and p38 was unaffected by sulfasalazine. The decrease in substrate phosphorylation by IKK-alpha and -beta is associated with a decrease in autophosphorylation of IKKs and can be antagonized by excess adenosine triphosphate.

Conclusions: These data identify sulfasalazine as a direct inhibitor of IKK-alpha and -beta by antagonizing adenosine triphosphate binding. The suppression of NF-kappaB activation by inhibition of the IKKs contributes to the well-known anti-inflammatory and immunosuppressive effects of sulfasalazine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / pharmacology
  • Cell Line
  • Drug Combinations
  • Enzyme Inhibitors / pharmacology*
  • Gastrointestinal Agents / pharmacology*
  • Humans
  • Hydrogen-Ion Concentration
  • I-kappa B Kinase
  • I-kappa B Proteins / metabolism
  • Jurkat Cells
  • NF-kappa B / antagonists & inhibitors*
  • Phosphorylation / drug effects
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / metabolism
  • Protein-Serine-Threonine Kinases / pharmacology
  • Sulfasalazine / pharmacology*
  • Transcription, Genetic / drug effects
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • Drug Combinations
  • Enzyme Inhibitors
  • Gastrointestinal Agents
  • I-kappa B Proteins
  • NF-kappa B
  • Tumor Necrosis Factor-alpha
  • Sulfasalazine
  • Adenosine Triphosphate
  • Protein-Serine-Threonine Kinases
  • CHUK protein, human
  • I-kappa B Kinase
  • IKBKB protein, human
  • IKBKE protein, human
  • NF-kappa B kinase