Abstract B18: MicroRNA-21 is involved in pancreatic cancer fibroblast tumor supportiveness

Abstract

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is characterized by poor survival despite current medical and surgical therapies and has a propensity towards subclinical metastasis even with resectable disease. The tumor microenvironment consists of a network of supporting cells, including tumor-associated fibroblasts (TAFs), which promote tumor invasion and metastasis, and contribute to PDAC’s extremely poor prognosis. MicroRNAs (miRs) have recently emerged as critical players in post-transcriptional regulation of pathways in cancer biology. In this study, we identified miRs in fibroblasts induced by PDAC tumor cells (TCs). Further, we study the stable suppression of one of these miRs in TAFs and the effects upon fibroblast migration and invasion, as well as tumor cell proliferation. Methods: Primary pancreatic fibroblasts were cultured with MIA PaCa-2 TC conditioned media and RNA was analyzed by the NanoString MicroRNA Expression Assay. Stable miR knockdown (KD) was achieved with a stably expressed shRNA anti-microRNA by lentiviral vector. Migration was determined by an 18 hour scratch assay and 24 hour invasion by modified Boyden chamber. TC proliferation was measured by MTT assay. In vivo tumor growth was evaluated by subcutaneous TC and TAF co-implantation in NSG mice. Results: In primary pancreatic fibroblasts, MIA PaCa-2 tumor cells induced 62 miRs >50% increase or 30% decrease in expression. The most prevalent induced miR with 2-fold increase in expression was miR-21. miR-21 KD in TAFs was achieved by introducing stable expression of anti-miR-21, which resulted in a 75% decrease in expression (P<0.001). miR-21 KD TAFs had a >50% decreased ability to migrate (p<0.001) and were 67% less invasive (p<0.001). miR-21 KD TAF conditioned media induced less rapid TC proliferation (p<0.05). Further, in an in vivo model of tumor proliferation, TCs co-implanted with miR-21 KD TAFs showed 45% decreased tumor size (P<0.05), compared to controls. Conclusions: Pancreatic cancer TCs can induce tumor supportive miRs in TAFs. miR-21 KD in PDAC TAFs results in decreased TAF migration and invasion, as well as reduced ability to support in vitro and in vivo tumor growth. Citation Format: Andrew Hieu Nguyen, Luyi Li, Paul Toste, Nanping Wu, Timothy R. Donahue. MicroRNA-21 is involved in pancreatic cancer fibroblast tumor supportiveness. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr B18.