Use of histone deacetylase inhibitors as small molecules is a promising approach to increase the differentiation efficiency of various cell types. In the present study, efficiency of the Histone deacetylase inhibitor Valproic acid (VPA) to induce endocrine differentiation in human exocrine pancreatic ductal adenocarcinoma cell line (Panc-1) was investigated. Panc-1 cells were cultured and treated with different concentrations of VPA and using quantitative real-time polymerase chain reaction regulation of pancreatic developmental genes were studied. The real-time PCR studies revealed an enhanced expression of pancreatic developmental genes Pdx1, Sox17, Ngn3, Pax6, Isl1, whereas very low regulation was observed in Foxa2 expression. Regulation of Ngn3 and Pdx1 were further looked at protein level by Western blots. Glucagon expression was found in cells treated with VPA, which was confirmed at protein level by Western blot, immunocytochemistry and measured glucagon content in the lysates by enzyme-linked immunoassay. Results from Western blots demonstrate enhanced acetylation of histones H3 and H4, which marks in the most cases active chromatin, indicating that the action of VPA on pancreatic differentiation occurred through the prevention of deacetylation of histones H3 and H4.The results collectively show that VPA induces the differentiation of Panc-1 cells into glucagon producing endocrine-like cells by induction of pancreatic genes through histone acetylation. Further understanding of the underlying mechanisms will highlight the current findings in the field of diabetes, and thus these cells can serve as tools for identifying compounds that convert alpha to beta cells as novel strategy for treatment of diabetes. VPA can also be interesting in diabetes studies that are focused on glucagon regulation or studies looking for mechanisms underlying glucagon dysregulation.
