The kinase inhibitor BX795 suppresses the inflammatory response via multiple kinases

Abstract

BX795, a small molecule with an aminopyrimidine backbone, is a potent ATP-competitive inhibitor of phosphoinositide-dependent kinase 1 (PDK1) and TANK-binding kinase 1 (TBK1). BX795 has significant functions in various immune responses and cancer. Few reports on the anti-inflammatory effect of BX795 are available, and its molecular mechanisms have not been fully elucidated. In this study, lipopolysaccharide (LPS)-treated macrophages (RAW264.7 cells), luciferase reporter gene assay, knock-down and overexpression strategies, kinase assay, protein chip, immunoprecipitation, and immunoblotting analyses were employed to clarify the anti-inflammatory mechanism of BX795. BX795 was found to dose-dependently inhibit the production of pro-inflammatory mediators without exhibiting cytotoxicity. Luciferase assay and immunoblotting analysis with nuclear fractions showed that activator protein-1 (AP-1), signal transducer and activator of transcription 1 (STAT1), and interferon regulatory factor 3 (IRF3) are targeted by BX795 rather than nuclear factor (NF)-κB. Moreover, TBK1 and AKT, transforming growth factor activated kinase (TAK)-1/c-Jun N-terminal kinase (JNK)/mitogen-activated protein kinase kinase 4 (MKK4) for AP-1 activation, and Janus kinase 2 (JAK2)/STAT1 were inhibited by BX795. Consistent with these findings, BX795 strongly ameliorated inflammatory symptoms in colitis models. These results suggest that BX795 can suppress inflammatory responses triggered by Gram-positive bacteria by suppressing multiple pathways.