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Hepatocellular carcinoma is one of the most common malignancies worldwide and evidence suggests that Ras signaling regulates various hallmarks of cancer via regulating several effector pathways such as ERK and PI3K. The aim of the present study is to understand the efficacy of a flavonoid myricetin for the first time in inhibiting the downstream target p21 activated kinase 1 (PAK1) of Ras signaling pathway in hepatocellular carcinoma. The analysis of gene expression revealed that myricetin inhibits PAK1 by abrogating the Ras-mediated signaling by decelerating Wnt signaling, the downstream of Erk/Akt, thereby inducing intrinsic caspase-mediated mitochondrial apoptosis by downregulating the expression of anti-apoptotic Bcl-2 and survivin and upregulating pro-apoptotic Bax. The results also provide striking evidence that the myricetin inhibits the development of HCC by inhibiting PAK1 via coordinate abrogation of MAPK/ERK and PI3K/AKT and their downstream signaling Wnt/β-catenin pathway, thus being a promising candidate for cancer prevention and therapy.

Shigella dysenteriae (S.dysenteriae) the causative agent of bacillary dysentery invades the human colonic epithelium resulting in severe intestinal inflammatory response and epithelial destruction. However, the mechanism by which S.dysenteriae infection regulates proinflammatory cytokines during intestinal inflammation is still obscure. In this study, we evaluated whether the interaction of β-catenin and NF-κB regulates proinflammatory cytokines TNF-α and IL-8 by modulating GSK-3β activity during S.dysenteriae infection in rat ileal loop model. Here we demonstrated that S.dysenteriae infection stimulate β-catenin degradation which in turn decreased the association between NF-κB and β-catenin. Also, we showed that S.dysenteriae infection increased GSK-3β kinase activity which in turn phosphorylates β-catenin for its degradation by ubiquitination and upregulates IL-8 through NF-κB activation thereby leading to inflammation. Thus these findings revealed the role of β-catenin/ NF-κB and GSK-3β in modulating the inflammatory response during bacterial infection and also showed that β-catenin acts as a critical regulator of inflammation.

Mucosal epithelial cells in the intestine act as the first line of host defense against pathogens by increasing mucin production for clearance. Despite this fact, the underlying molecular mechanisms by which Shigella dysenteriae transduce mucin gene expression remain poorly defined. The goal of this study was to determine the role of Bone morphogenetic protein (BMP) pathway in mucin gene expression during S. dysenteriae infection. In this study we demonstrate that S. dysenteriae activates BMP signaling to induce MUC2 and MUC5AC gene expression in rat ileal loop model and in vitro. We also observed that BMP pathway regulates CDX2 expression which plays a critical role in induction of MUC2 gene during S. dysenteriae infection. In SMAD4 silenced cells S. dysenteriae infection did not abrogate MUC2 and MUC5AC gene expression whereas in CDX2 silenced cells it induces differential expression of MUC5AC gene. These results suggest that SMAD4-CDX2 induces MUC2 gene expression whereas SMAD4 directly influences differential expression of MUC5AC gene. Altogether, our results show that during S. dysenteriae infection the BMP pathway modulates inflammatory transcription factors CDX2 and SMAD4 to induce MUC2 and MUC5AC gene expression which plays a key role in the regulation of host mucosal defense thereby paving a cue for therapeutic application.