Impact and Mechanistic Role of Microrna-1291 on Pancreatic Tumorigenesis.

243 Background: Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer death. Better understanding of pancreatic cancer biology and identification of new targets are highly warranted. MicroRNAs (miRs or miRNAs) play a critical role in the control of tumor progression via crosstalk with cancer signaling pathways. Our recent studies showed that miR-1291 improved chemosensitivity through targeting of efflux transporter ABCC1. This current study investigated the mechanistic role of miR-1291 in the suppression of pancreatic tumorigenesis. Methods: PANC-1 and AsPC-1 cell lines were stably transfected with miR-1291. Cell cycle status and apoptosis of stable miR-1291-expressing cells were tested against control cells using flow cytometry. Cells were injected subcutaneously into nude mice and tumorigenesis was measured in vivo. Proteomic studies were performed by two-dimensional difference gel electrophoresis, matrix-assisted laser desorption/ionization time of flight mass spectrometry analysis. Computationally predicted miR-1291 targets were assessed by luciferase reporter assay and Western blot. Primary PDAC and control samples were tested for miR-1291 and target gene expression levels. Results: Our data showed that stable miR-1291-expressing PANC-1 and AsPC-1 cells both showed a significantly lower rate of proliferation than the control cells, which was associated with a cell cycle arrest and enhanced apoptosis. Furthermore, miR-1291 suppressed the tumorigenesis of PANC-1 cells in mouse models in vivo. Proteomic studies revealed the protein level of several cancer-related genes were downregulated by miR-1291, including a pancreatic tumor promoting protein AGR2 which was reduced ~10-fold. Through computational and experimental studies we further identified that FOXA2, a transcription factor governing AGR2 expression, was a direct target of miR-1291. In addition, we found a significant down-regulation of miR-1291 in a set of PDAC patient tumor samples overexpressing AGR2. Conclusions: These results indicate that miR-1291 suppresses pancreatic tumorigenesis via targeting of FOXA2-AGR regulatory pathway providing new insight supporting development of miR-1291-based therapy for PDAC.