A preferential p110alpha/gamma PI3K inhibitor attenuates experimental inflammation by suppressing the production of proinflammatory mediators in a NF-kappaB-dependent manner.

A promising therapeutic approach to diminish pathological inflammation is to inhibit the increased production and/or biological activity of proinflammatory cytokines (e.g., TNF-alpha, IL-6). The production of proinflammatory cytokines is controlled at the gene level by the activity of transcription factors, such as NF-kappaB. Phosphatidylinositol 3-kinase (PI3K), a lipid kinase, is known to induce the activation of NF-kappaB. Given this, we hypothesized that inhibitors of PI3K activation would demonstrate anti-inflammatory potential. Accordingly, we studied the effects of a preferential p110alpha/gamma PI3K inhibitor (compound 8C; PIK-75) in inflammation-based assays. Mechanism-based assays utilizing human cells revealed that PIK-75-mediated inhibition of PI3K activation is associated with dramatic suppression of downstream signaling events, including AKT phosphorylation, IKK activation, and NF-kappaB transcription. Cell-based assays revealed that PIK-75 potently and dose dependently inhibits in vitro and in vivo production of TNF-alpha and IL-6, diminishes the induced expression of human endothelial cell adhesion molecules (E-selectin, ICAM-1, and VCAM-1), and blocks human monocyte-endothelial cell adhesion. Most importantly, PIK-75, when administered orally in a therapeutic regimen, significantly suppresses the macroscopic and histological abnormalities associated with dextran sulfate sodium-induced murine colitis. The efficacy of PIK-75 in attenuating experimental inflammation is mediated, at least in part, due to the downregulation of pertinent inflammatory mediators in the colon. Collectively, these results provide first evidence that PIK-75 possesses anti-inflammatory potential. Given that PIK-75 is known to exhibit anti-cancer activity, the findings from this study thus reinforce the cross-therapeutic functionality of potential drugs.

Synthesis and therapeutic evaluation of pyridyl based novel mTOR inhibitors.

A series of novel cyanopyridyl based molecules (1-14) were designed, synthesized and probed for inhibition of mammalian target of rapamycin (mTOR) activity. Compound 14 was found to be a potent inhibitor of mTOR activity as assessed by enzyme-linked immunoassays and Western blot analysis. Most importantly, systemic application (intraperitoneal; ip) of compound 14 significantly suppressed macroscopic and histological abnormalities associated with chemically-induced murine colitis.

A novel mTOR inhibitor is efficacious in a murine model of colitis.

Ulcerative colitis is an autoimmune-inflammatory disease characterized by increased proliferation of colonic epithelial cells, dysregulation of signal transduction pathways, elevated mucosal T cell activation, increased production of proinflammatory cytokines, and enhanced leukocyte infiltration into colonic interstitium. Several compounds that possess antiproliferative properties and/or inhibit cytokine production exhibit a therapeutic effect in murine models of colitis. Mammalian target of rapamycin (mTOR), a protein kinase regulating cell proliferation, is implicated in colon carcinogenesis. In this study, we report that a novel haloacyl aminopyridine-based molecule (P2281) is a mTOR inhibitor and is efficacious in a murine model of human colitis. In vitro studies using Western blot analysis and cell-based ELISA assays showed that P2281 inhibits mTOR activity in colon cancer cells. In vitro and in vivo assays of proinflammatory cytokine production revealed that P2281 diminishes induced IFN-gamma production but not TNF-alpha production, indicating preferential inhibitory effects of P2281 on T cell function. In the dextran sulfate sodium (DSS) model of colitis, 1) macroscopic colon observations demonstrated that P2281 significantly inhibited DSS-induced weight loss, improved rectal bleeding index, decreased disease activity index, and reversed DSS-induced shortening of the colon; 2) histological analyses of colonic tissues revealed that P2281 distinctly attenuated DSS-induced edema, prominently diminished the leukocyte infiltration in the colonic mucosa, and resulted in protection against DSS-induced crypt damage; and 3) Western blot analysis showed that P2281 blocks DSS-induced activation of mTOR. Collectively, these results provide direct evidence that P2281, a novel mTOR inhibitor, suppresses DSS-induced colitis by inhibiting T cell function and is a potential therapeutic for colitis. Given that compounds with anticancer activity show promising anti-inflammatory efficacy, our findings reinforce the cross-therapeutic functionality of potential drugs.