Compromised Ileal Mucus Barrier Due to Impaired Epithelial Homeostasis Caused by Notch1 Signaling in Cirrhotic Rats

Inhibition of Transketolase Improves the Prognosis of Colorectal Cancer

Colorectal cancer (CRC) remains a heavy health burden worldwide. Transketolase (TKT) is a crucial enzyme in the non-oxidative phase of the Pentose Phosphate Pathway (PPP), and is up-regulated in multiple cancer types. However, the role of TKT in the prognosis of CRC remains unclear. We aimed to explore whether TKT expression is altered in CRC, how TKT is associated with the prognosis of CRC, and whether the regulation of TKT might have an impact on CRC. Differentially expressed genes (DEGs) were identified using bioinformatics analysis. TKT expression was examined in the human colon adenocarcinoma tissue microarray and xenografts. Cell viability, proliferation, migration, and apoptosis assays in vitro were applied to evaluate the protumoral effects of TKT on CRC. TKT was found to be a risk factor for the poor prognosis of CRC by bioinformatics analysis among the DEGs. TKT was significantly up-regulated in colon adenocarcinoma tissues compared with normal colon tissues in patients. Moreover, similar results were found in HCT116 and RKO human colon adenocarcinoma xenografts in nude mice. TKT expression was positively associated with advanced TNM stage, positive lymph nodes, and poor 5 or 10-year overall survival of CRC patients. In vitro, inhibition of TKT reduced cell viability, proliferation, and migration, and induced cell apoptosis. In addition, inhibition of TKT decreased the protein levels of NICD and Hes1. In conclusion, high TKT expression was associated with the poor prognosis of CRC patients. The protumoral effects of downregulating TKT may be realized by suppressing the Notch signaling pathway. TKT may be a new prognostic biomarker and therapeutic target for CRC.

Inhibition of cyclooxygenase-2 enhanced intestinal epithelial homeostasis via suppressing β-catenin signalling pathway in experimental liver fibrosis

The intestinal barrier dysfunction is crucial for the development of liver fibrosis but can be disturbed by intestinal chronic inflammation characterized with cyclooxygenase‐2 (COX‐2) expression. This study focused on the unknown mechanism by which COX‐2 regulates intestinal epithelial homeostasis in liver fibrosis. The animal models of liver fibrosis induced with TAA were established in rats and in intestinal epithelial–specific COX‐2 knockout mice. The impacts of COX‐2 on intestinal epithelial homeostasis via suppressing β‐catenin signalling pathway were verified pharmacologically and genetically in vivo. A similar assumption was tested in Ls174T cells with goblet cell phenotype in vitro. Firstly, disruption of intestinal epithelial homeostasis in cirrhotic rats was ameliorated by celecoxib, a selective COX‐2 inhibitor. Then, β‐catenin signalling pathway in cirrhotic rats was associated with the activation of COX‐2. Furthermore, intestinal epithelial–specific COX‐2 knockout could suppress β‐catenin signalling pathway and restore the disruption of ileal epithelial homeostasis in cirrhotic mice. Moreover, the effect of COX‐2/PGE2 was dependent on the β‐catenin signalling pathway in Ls174T cells. Therefore, inhibition of COX‐2 may enhance intestinal epithelial homeostasis via suppression of the β‐catenin signalling pathway in liver fibrosis.