A Novel, Highly Selective, Tight Binding I kappa B Kinase-2 (IKK-2) Inhibitor: A Tool to Correlate IKK-2 Activity to the Fate and Functions of the Components of the Nuclear Factor-kappa B Pathway in Arthritis-Relevant Cells and Animal Models

作者：Mbalaviele Gabriel^*; Sommers Cynthia D; Bonar Sheri L; Mathialagan Sumathy; Schindler John F; Guzova Julia A; Shaffer Alexander F; Melton Michele A; Christine Lori J; Tripp Catherine S; Chiang Po Chang; Thompson David C; Hu Yiding; Kishore Nandini

来源：Journal of Pharmacology and Experimental Therapeutics, 2009, 329(1): 14-25.

DOI：10.1124/jpet.108.143800

Nuclear factor (NF)-kappa B activation has been clearly linked to the pathogenesis of multiple inflammatory diseases including arthritis. The central role that I kappa B kinase-2 (IKK-2) plays in regulating NF-kappa B signaling in response to inflammatory stimuli has made this enzyme an attractive target for therapeutic intervention. Although diverse chemical classes of IKK-2 inhibitors have been identified, the binding kinetics of these inhibitors has limited the scope of their applications. In addition, safety assessments of IKK-2 inhibitors based on a comprehensive understanding of the pharmacokinetic/pharmacodynamic relationships have yet to be reported. Here, we describe a novel, potent, and highly selective IKK-2 inhibitor, PHA-408 [8-(5-chloro-2-(4-methylpiperazin-1- yl)isonicotinamido)-1-(4-fluorophenyl)-4,5-dihydro-1H- benzo[g] indazole-3-carboxamide]. PHA-408 is an ATP-competitive inhibitor, which binds IKK-2 tightly with a relatively slow off rate. In arthritis-relevant cells and animal models, PHA-408 suppresses inflammation-induced cellular events, including I kappa B-phosphorylation and degradation, p65 phosphorylation and DNA binding activity, the expression of inflammatory mediators, and joint pathology. PHA-408 was efficacious in a chronic model of arthritis with no adverse effects at maximally efficacious doses. Stemming from its ability to bind tightly to IKK-2, as a novelty, we demonstrated that PHA-408-mediated inhibition of IKK-2 activity correlated very well with its ability to modulate the fate of IKK-2 substrates and downstream transcriptional events. We ultimately directly linked IKK-2 activity ex vivo and in vivo to markers of inflammation with the inhibitor plasma concentrations. Thus, PHA408 represents a powerful tool to further gain insight into the mechanisms by which IKK-2 regulates NF-kappa B signaling and validates IKK-2 as a therapeutic target.

• 出版日期2009-4