Abstract 514: Focal Adhesion Kinase Inhibition Prevents Prolonged Nuclear Factor-κB Activation and Reduces Atherosclerosis in ApoE-/- Mice

A key event in atherogenesis is the expression of cell adhesion molecules on endothelial cells (ECs) that recruit leukocytes to the vessel wall, where they accumulate over time and form atherosclerotic plaques filled with fatty lipids. Although lipid-lowering drugs have been beneficial in slowing down atherosclerosis, there is currently no treatment available to reduce the underlying triggers that promote EC activation. Focal adhesion kinase (FAK) is an integrin-associated protein tyrosine kinase that plays a key role in cytokine-induced pro-inflammatory molecule expression; however, the molecular mechanism has not been elucidated. We have revealed that a small molecule FAK inhibitor (PF-271) in human ECs reduces tumor necrosis factor-α (TNF-α)-induced sustained activation of nuclear factor-κB (NF-kB), a major inflammatory transcription factor. While NF-κB is normally bound to inhibitor of NF-κB α (IκBα) in the cytosol, TNF-α leads to rapid activation and nuclear localization of NF-κB after degradation of IκBα by activation of IκB kinase (IKK). Chronic exposure to cytokines leads to oscillations in NF-κB activation as IκBα is continually made by active NF-κB and degraded by active IKK. Surprisingly, we discovered that FAK inhibition blocks prolonged NF-κB activation through a time-dependent increase in IκBα protein stability, suggesting decreased IKK activity. By performing in vitro IKK kinase assays, we found that FAK inhibition did indeed reduce sustained IKK activity as seen by reduced serine phosphorylation of IκBα 3hr after TNF-α stimulation. Since both cell adhesion molecule expression and NF-κB in ECs is important for atherosclerotic lesion development, we tested the efficacy of FAK inhibition on atherogenesis in vivo . We found that oral delivery of PF-271 (twice daily, 8 weeks) significantly reduced atherosclerotic lesion area in ApoE-/- mice fed a western diet. Taken together, our data demonstrates that FAK inhibition potentially reduces atherogenesis by blocking sustained NF-κB signaling through decreased IKK activity.