Analysis of the Relationship Between Notch Signaling Pathway and Cdx2 Expression in the Development of Barrett's Esophagus

Introduction: Cdx2 expression in the esophageal stem cells induced by reflux bile acids may be an important factor for the development of Barrett's esophagus. Notch signaling is a molecular signaling pathway that plays an important role in the determination of cell differentiation. It has been reported that the induction of Cdx2 in the intestinal epithelium leads to the induction of Hath1 (a factor associated with Notch signaling), and that Hath1 plays an important role in the differentiation of stem cells into goblet cells. This study was performed to investigate the interrelation between Cdx2 and Notch signaling in esophageal epithelial cells. Methods'. The authors examined the expression of Cdx2, MUC2, and intracellular signaling molecules related to Notch signaling (Notch1, Hes1, and Hath1) by real-time polymerase chain reaction (PCR) and immunohistochemical staining in the biopsy specimen taken from esophageal intestinal metaplasia with goblet cells and columnar epithelium not accompanied by goblet cells. In an in vitro study, the esophageal adenocarcinoma cell line (OE33 and OE19) was employed. After forced Cdx2 expression by applying a Cdx2 expression vector to the cells, the changes in the expression of Notch1, Hes1, Hath1, Cdx2, and MUC2 by real-time PCR and Western blot analysis were performed. Changes in the expression of Notch1, Hes1, Hath1, Cdx2, and MUC2 in cells into the stimulation with bile acids in the presence or absence of Cdx2 blocking with Cdx2-siRNA were also analyzed. Result: Tissue specimens of intestinalized Barrett's epithelium with goblet cells showed suppressed Hes1 and enhanced Hath1 and MUC2 expression. Forced expression of Cdx2 in cells suppressed Hes1 and enhanced Hath1 and MUC2 expression. Stimulation of the cells with bile acids resulted in suppressed Hes1 and enhanced Hath1 and MUC2 expression. On the other hand, in the presence of Cdx2-siRNA, Hes1 expression was enhanced and Hath1 expression was suppressed. In Cdx2-siRNA treated cells, bile acids did not change Hes1, Hath1, and MUC2 expression. Conclusion: The enhanced expression of Cdx2 by stimulation with bile acids may induce intestinal differentiation of esophageal columnar cells by interaction with Notch signaling pathways.