Abstract 4187: Regulation of NRSF/REST by miR-217; Implications during pancreatic acinar ductal trans-differentiation.

Abstract Pancreatic ductal adenocarcinoma is believed to arise from exocrine acinar cells following trans-differentiation to cells with a more epithelial phenotype. A pancreas enriched cluster of miRNAs (miR-216a/b-217) is located on chromosomes 2 and 11 in humans and mice, respectively. These miRNAs are significantly reduced in patient's tumor specimens and during tumor progression in a transgenic mouse model of pancreatic ductal adenocarcinoma. To investigate a role for miR-216/-217 during acinar ductal trans-differentiation, we used a model by which primary mouse pancreatic acini trans-differentiate into epithelial-like cells when cultured on matrigel. Over a 4 day culture period, the acini develop an epithelial morphology and display reduced mRNA expression of the acinar marker amylase, increased expression of the epithelial marker cytokeratin-19 (KRT19) and reduced expression miR-216/-217. Forced expression of miR-217 using a lentiviral vector (LV) decreased KRT19 mRNA expression compared to the empty vector control treated cells on day 4 of the trans-differentiation. To implicate miR-217 targets in regulating acinar trans-differentiation, we considered REST/NRSF, a transcriptional repressor of neuronal genes in non-neuronal tissues. REST mRNA expression increased during the 4 day trans-differentiation implying regulation of REST by miR-217. Regulation of REST by miR-217 was validated using a luciferase assay and western blotting. Furthermore, two REST target genes were upregulated by the miR-217 LV on day 4 of the trans-differentiation. Studies are ongoing to determine if this increase in expression results from miR-217 suppressing REST protein levels. Additionally, miR-217 LV infection of 3 pancreas cancer cell lines reduced REST protein and caused significant cell death. Our current focus is to establish a link between miR-217 suppression of REST and cell death. We report a connection between reduced miR-217 in several pancreas model systems. We hypothesize a novel role for REST in pancreas homeostasis and cancer. Citation Format: Ana Clara P. Azevedo-Pouly, Jinmai Jiang, Dhruvitkumar Sutaria, Thomas Schmittgen. Regulation of NRSF/REST by miR-217; Implications during pancreatic acinar ductal trans-differentiation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4187. doi:10.1158/1538-7445.AM2013-4187