Activation of phosphatidylinositol-3 kinase regulates pancreatic duodenal homeobox-1 in duct cells during pancreatic regeneration.

OBJECTIVE: The purpose of our study was to determine whether the phosphatidylinositol 3-kinase (PI3K)/Akt pathway contributes to expression of pancreatic duodenal homeobox-1 (PDX-1) in duct cells and the cell differentiation during pancreatic regeneration. METHODS: The role of PI3K in PDX-1 expression and duct cell differentiation with pancreatic regeneration in mice after partial pancreatectomy (Px) was examined using either wortmannin, a pharmacological PI3K inhibitor, or small-interfering RNA directed to the p85alpha regulatory subunit of PI3K. Akt phosphorylation, a marker of PI3K activation, and PDX-1 expression were assessed by Western blot analysis and immunohistochemistry. RESULTS: Both PDX-1 levels and Akt phosphorylation were concomitantly increased in pancreatic ducts after partial Px and, conversely, blocked by treatment with wortmannin or p85alpha small-interfering RNA. Pancreatic duct cell differentiation, as assessed by appearance of insulin-positive cells 3 days after partial Px, was effectively reduced by wortmannin. CONCLUSIONS: The PI3K/Akt activation plays a critical role for both PDX-1 expression and pancreatic duct cell differentiation into insulin-producing cells during pancreatic regeneration.