A Selective Small Molecule IκB Kinase β Inhibitor Blocks Nuclear Factor κB-Mediated Inflammatory Responses in Human Fibroblast-Like Synoviocytes, Chondrocytes, and Mast Cells

Abstract

IB kinase (IKK) ␤ is essential for inflammatory cytokine-induced activation of nuclear factor B (NF-B). NF-B plays a pivotal role in the function of major cell types that contribute to the pathophysiological process of rheumatoid arthritis (RA). Here, we report the mechanism and the effect of the IKK␤ inhibitor N- (6-chloro-7-methoxy-9H-␤-carbolin-8-yl)-2-methylnicotinamide (ML120B), a ␤-carboline derivative, on NF-B signaling and gene activation in RA-relevant cell systems. ML120B is a potent, selective, reversible, and ATP-competitive inhibitor of IKK␤ with an IC 50 of 60 nM when evaluated in an IB␣ kinase complex assay. ML120B does not inhibit other IKK isoforms or a panel of other kinases. ML120B concentrationdependently inhibits tumor necrosis factor ␣ (TNF␣)-stimulated NF-B signaling via inhibition of IB␣ phosphorylation, degradation, and NF-B translocation into the nucleus. For the first time, we have demonstrated that in human fibroblast-like synoviocytes, TNF␣-or interleukin (IL)-1␤-induced monocyte chemoattractant protein-1 regulated on activation, normal T cell expressed and secreted and production is IKK␤-dependent. In addition, for the first time, we have demonstrated that lipopolysaccharide-or peptidoglycan-induced cytokine production in human cord blood-derived mast cells is IKK␤-dependent. In addition, in human chondrocytes, ML120B inhibited IL-1␤-induced matrix metalloproteinase production with an IC 50 of approximately 1 M. ML120B also blocked IL-1␤-induced prostaglandin E 2 production. In summary, ML120B blocked numerous NF-B-regulated cell responses that are involved in inflammation and destructive processes in the RA joint. Our findings support the evaluation of IKK␤ inhibitors as anti-inflammatory agents for the treatment of RA.

Biologic sequelae of IκB kinase (IKK) inhibition in multiple myeloma: therapeutic implications

“…To characterize the biologic sequelae of specific NF-B inhibition in MM, we have previously used specific IKK␤ inhibitors PS-1145 4 and MLN120B, 12 which completely block TNF-␣-induced NF-B activation, MM cell growth in the context of BMSCs, and IL-6 secretion from BMSCs triggered by MM cell adhesion. However, the direct growth inhibitory effect of these agents against MM cells is modest.…”

Chemical biology of inflammatory cytokine signaling

“…5-Bromo-6-methoxy-b-carboline, a methylated natural product derivative, was initially obtained as a lead compound that non-specifically inhibits endogenous IKK and other kinases, and further chemical optimization has led to the identification of N-(6-chloro-9H-b-carbolin-8-yl)nicotinamide (PS-1145) as a selective IKKb inhibitor and N-(6-chloro-7-methoxy-9H-b-carbolin-8-yl)-2-methylnicotinamide (ML120B) as a more potent, reversible and ATP-competitive IKKb inhibitor. [24][25][26][27] 4-Amino-2,3¢-bithiophene-5-carboxamide (SC-514), an ATP-competitive IKKb inhibitor, has an IC 50 value 410 mM, but has little or no inhibitory effect on other kinases. 28 On the basis of the thiophenecarboxamide structure, more potent thiophenecarboxamide-type IKKb inhibitors, such as 2-((aminocarbonyl)amino)-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1), as well as benzothieno(3,2-b)furan derivatives as novel IKKb inhibitors, have been developed independently by four individual groups.…”

Normalization of A2A and A3 adenosine receptor up‐regulation in rheumatoid arthritis patients by treatment with anti–tumor necrosis factor α but not methotrexate

“…In RA patients, the overexpression of A 3 adenosine receptor has been directly correlated with high levels of proinflammatory cytokines acting via up-regulation of NF-B, the DNA binding sites of which are present in the promoter of the A 3 receptor gene (31,32). A 3 agonists are also able to deregulate phosphatidylinositol 3-kinase/NF-B, which controls the NF-B signal transduction pathway (31,33). RA patients treated with A 3 agonists have shown improvement in clinical symptoms (34,35).…”