Inhibition of NF-kappa B activation through targeting I kappa B kinase by celastrol, a quinone methide triterpenoid

Biochem Pharmacol. 2006 Nov 15;72(10):1311-21. doi: 10.1016/j.bcp.2006.08.014. Epub 2006 Sep 18.


Celastrol, a quinone methide triterpenoid, was isolated as an inhibitor of NF-kappaB from Celastrus orbiculatus. This compound dose-dependently inhibited a variety of stimuli-induced NF-kappa B-regulated gene expression and the DNA-binding of NF-kappa B in different cell lines without affecting DNA-binding activity of AP-1. Preincubation of celastrol completely blocked the LPS-, TNF-alpha-, or PMA-induced degradation and phosphorylation of I kappa B alpha. Importantly, celastrol inhibited IKK activity and the constitutively active IKK beta activity in a dose-dependent manner without either affecting the NF-kappa B activation induced by RelA over-expression or directly suppressing the DNA-binding of activated NF-kappa B. However, mutation of cysteine 179 in the activation loop of IKK beta abolished sensitivity towards to celastrol, suggesting that celastrol suppressed the NF-kappa B activation by targeting cysteine 179 in the IKK. To verify that celastrol is a NF-kappa B inhibitor, we investigated its effect on some NF-kappa B target genes expressions. Celastrol prevented not only LPS-induced mRNA expression of iNOS and TNF-alpha, but also TNF-alpha-induced Bfl-1/A1 expression, a prosurvival Bcl-2 homologue. Consistent with these results, celastrol significantly suppressed the production of NO and TNF-alpha in LPS-stimulated RAW264.7 cells, and increased the cytotoxicity of TNF-alpha in HT-1080 cells. We also demonstrated that celastrol showed anti-inflammatory and anti-tumor activities in animal models. Taken together, this study extends our understanding on the molecular mechanisms underlying the anti-inflammatory and anti-cancer activities of celastrol and celastrol-containing medicinal plant, which would be a valuable candidate for the intervention of NF-kappa B-dependent pathological conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacology*
  • Anti-Inflammatory Agents, Non-Steroidal / therapeutic use
  • Antineoplastic Agents / pharmacology*
  • Antineoplastic Agents / therapeutic use
  • DNA-Binding Proteins / metabolism
  • Female
  • Gene Expression / drug effects
  • Genes, Reporter
  • HeLa Cells
  • Humans
  • I-kappa B Kinase / antagonists & inhibitors*
  • I-kappa B Kinase / genetics
  • Inflammation / drug therapy
  • Inflammation / enzymology
  • Inflammation / metabolism
  • Jurkat Cells
  • Mice
  • Mice, Nude
  • NF-kappa B / antagonists & inhibitors*
  • NF-kappa B / genetics
  • Neoplasms, Experimental / drug therapy
  • Neoplasms, Experimental / enzymology
  • Neoplasms, Experimental / metabolism
  • Phosphorylation
  • Triterpenes / pharmacology*
  • Triterpenes / therapeutic use


  • Anti-Inflammatory Agents, Non-Steroidal
  • Antineoplastic Agents
  • DNA-Binding Proteins
  • NF-kappa B
  • Triterpenes
  • I-kappa B Kinase
  • celastrol