The Second-Generation mTOR Kinase Inhibitor INK128 Exhibits Anti-inflammatory Activity in Lipopolysaccharide-Activated RAW 264.7 Cells

Cross-talk between the mTOR (mechanistic target of rapamycin) and NF-kappa B (nuclear factor kappa-B) pathways has been reported to regulate macrophage responses to lipopolysaccharide (LPS). In this study, we aimed to explore the effect of INK128, a second-generation inhibitor of mTOR, on the inflammatory cytokine production in LPS-stimulated RAW 264.7 cells. Our data showed that INK128 strikingly inhibited the phosphorylation of p70S6K, 4E-BP1 and AKT(Ser473) in both unstimulated and LPS-stimulated cells. Although it increased the phosphorylation levels of inhibitor kappa-B (I kappa B) in LPS-stimulated cells, INK128 did not significantly change the levels of NF-kappa B phosphorylation. In addition, LPS-induced expression of IL-1 beta and IL-6 was markedly suppressed by INK128 at both mRNA and protein levels. However, the expression of Tumor necrosis factor-alpha (TNF-alpha protein), but not its mRNA level, was suppressed by this reagent. Our results suggest that the mTOR inhibitor INK128 not only regulates the NF-kappa B signaling but also influences the inflammatory cytokine expression at both transcriptional and translational levels.