Abstract 6285: MicroRNA-217 affects tumor microenvironment and enhances the chemosensitivity of pancreatic cancer

Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies and an inherently chemoresistant tumor. Dense fibrotic stroma is a major obstacle for drug delivery to the tumor cells in PDAC. Pancreatic stellate cells (PSCs) are the major stromal cells responsible for fibrotic microenvironment. MicroRNA-217 (miR-217) is known mainly as a tumor suppressor. However, the detailed roles of miR-217 on pathophysiology of PDAC remain unclarified. Methods: Expressions levels of miR-217 were measured in surgically resected human PDAC samples. Using Lipofectamine RNAiMAX, miR-217 or negative control miR (NC) were transfected in human pancreatic cancer cells, Panc-1, MIApaca-2, BxPC-3 and murine PAN02 cells, and chemosensitivities to gemcitabine and paclitaxel were investigated by MTS assay. Human hPSC-1 (obtained from Riken cell bank, Japan) was cultured in 20%FBS+DMEM and the changes of phenotypes and expression levels of miR-217 after the stimulation with TGF-β1 was measured by fluorescein microscope and digital PCR, respectively. Results: The expression level of miR-217 was markedly downregulated in PDAC tissues than in noncancerous pancreatic tissues (P