Abstract 769: Mechanistic role of miR-29 in pancreatic ductal adenocarcinoma progression

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers with a 5-year survival rate of 8% (Kota et al., 2017, Cancer Lett.). Lack of curative treatment for PDAC warrants better understanding of its mechanisms. Our previous work demonstrated that miR-29 is commonly downregulated in PDAC, while its restoration exhibits tumor-suppressive effects (Kwon et al., 2016, Oncotarget; Kwon et al., 2015, Sci Rep.). To understand these mechanisms, first we performed siRNA mediated knockdown of several miR-29 promoter binding transcription factors, including MYC, which play a role in PDAC. Our results indicate MYC represses miR-29 expression, and MYC nuclear localization negatively correlates with miR-29 in pancreatic cancer cells (PCCs). Next, to identify global miR-29 targets associated with PDAC, we conducted RNAseq on two miR-29 overexpressing PCC lines. This identified 41 overlapping miR-29 targets downregulated in both datasets. Gene ontology and survival correlation analyses identified seven most prominent targets (LOXL2, MYBL2, TRIB2, HGK, NRAS, CD276 and CLDN1). Ectopic expression of miR-29 significantly altered protein levels of these genes, confirming a translational suppression mechanism mediated by miR-29. RNAi mediated silencing of these targets significantly reduced the migratory ability of the PCCs. Our top target LOXL2 is involved in regulation of EMT/migration and extracellular matrix (ECM) remodeling. Luciferase reporter assay verified LOXL2 as a direct miR-29 target in PDAC. Immunohistochemical analyses in clinical specimens from PDAC patients and KPC mice pancreatic tissues showed higher LOXL2 expression in regions of pancreatic intraepithelial neoplasia (PanIN) lesions as compared to non-cancerous areas. This increased LOXL2 level was accompanied by concomitant reduction in miR-29 expression. Thus, our current study provides insight into new miR-29 mediated regulatory pathways in PDAC and reveals the association of miR-29-LOXL2 axis in the disease progression. Together, our data suggest miR-29 to play a critical role in mechanisms of PDAC progression and could serve as a potential therapeutic target for the disease. Citation Format: Shatovisha Dey, Jason J. Kwon, Sheng Liu, Tricia Factoria, Gabriel A. Hodge, Jun Wan, Janaiah Kota. Mechanistic role of miR-29 in pancreatic ductal adenocarcinoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 769.