Abstract 821: miRNA profiling and target identification during normal pancreata transformation to PanINs to pancreatic ductal cancer progression in p48Cre/+-LSL-KrasG12D/+ mice: Implication for human pancreatic cancer chemoprevention and treatment

miRNA expression levels and their target genes during development of pancreatic intraepithelial neoplasia (PanINs), more so, in ductal adenocarcinomas (PDAC) remain largely unknown. Understanding miRNA regulated disease progression from PanINs to PDAC would provide opportunities to develop novel chemopreventive and therapeutic strategies. miRNA and mRNA were isolated from pancreatic tissues (normal, PanINs and PDAC from LSL-Kras G12D/+ mice). Eighty-eight miRNAs were profiled through RT-PCR using miRNA Array. miRNA target genes were identified by bioinformatics (Target Scan, Microcosm) and confirmed by RT-PCR and IHC. During PanIN 1 stage, miR-1, miR-183, Let7g, miR-124, let7-f, miR-10a, and miR-16 were significantly down-regulated (142, 4, 12, 5, 30, 7, 5 folds respectively), in contrast to miR25 (14 fold up-regulation). At PanIN-2 & -3 stages, 22 miRNAs were over-expressed and 11 miRNAs, miR-133b, miR-122, miR-196a, miR-148a, miR-92a, miR-137, miR-212, miR-1, miR363, miR-219, miR-193 (17, 9, 10, 4, 19, 22, 5, 11, 4.5, 4.3, 9.5 folds, respectively) were down-regulated compared to normal pancreas. Whereas, in PDAC, miR-184 (7 folds) and miR-150 (8 folds) were significantly over expressed and miR-133b, miR-222, miR92a, miR-140, miR-148a, miR-7a (15, 31, 116, 4, 4.2, 156 folds, respectively) were down-regulated based on volcano plot analysis. Notably, miR-1 was down-regulated during all PanIN stages (PanIN1 to 3). Also, miR-133b, miR-122, miR-92a, and miR-148a were down-regulated at PanIN 3 & PDAC. Most prominently, at PanIN 1 stage, Ras MAPK pathway (let7-g, let7-f, miR124) was activated through HDAC4 controlled by miR-1. Also, pathfinder results suggest that insulin (let7-g and let7-f) and glutamate receptor (miR-10a, miR16) signaling were disrupted at PanIN 1 stage. miRNA data suggests that disruption of glucose metabolism leads to increased FAS controlled by miR-1. MiR-25 up-regulation suggests an effect on TGF-β signaling through importin-β family proteins at PanIN1 stage. Importantly, miR-92a showed increase of ornithine decarboxylase (ODC) activity at PanIN-3 and PDAC. Similarly, miR-150 and miR-145a, regulators of β-catenin and Gadd45a, respectively, were noted to be deregulated at the PanIN 3 and PDAC. Overall, altered miRNAs target genes from PanIN progression to PDAC confirmed by RT-PCR and IHC include, ODC, HDAC4, IR substrate 1, TGFβ receptor protein 1, FAS, cyclin D1, profilin 2, exportin 4, glutaminase, p38, VEGF, p21, Bcl-2, β-catenin, p2X7, E2F1, AKT, and Gadd45a. Our data supports that miRNAs and their regulatory genes provide pathways involved in PanINs progression to PDAC. This information may help in targeting miRNAs or their regulated genes at different stages of pancreatic tumor progression. (Supported by NIH N01 CN-53300) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 821. doi:10.1158/1538-7445.AM2011-821