MicroRNA-769-5p Inhibits Pancreatic Ductal Adenocarcinoma Progression by Directly Targeting and Downregulating ETS Proto-Oncogene 1

PURPOSE: MicroRNA-769-5p (miR-769) is aberrantly expressed and plays crucial roles in non–small cell lung cancer and melanoma. However, the expression pattern, biological role, and mechanisms of action of miR-769 in pancreatic ductal adenocarcinoma (PDAC) are yet to be fully elucidated. Therefore, we attempted to determine the potential regulatory function of miR-769 in PDAC progression and to explore the underlying mechanisms in detail. METHODS: In this study, reverse-transcription quantitative polymerase chain reaction was carried out to determine the expression profile of miR-769 in PDAC. A series of experiments, including a Cell Counting Kit-8 assay, flow-cytometric analysis, Transwell migration and invasion assays, and a xenograft animal model, were applied to test whether miR-769 affects the malignancy of PDAC. RESULTS: We found that miR-769 was significantly underexpressed in PDAC tissues and cell lines. The low miR-769 expression significantly correlated with the TNM stage and lymph node metastasis. Patients with PDAC harboring low miR-769 expression showed shorter overall survival than did the patients with high miR-769 expression. Forced upregulation of miR-769 suppressed PDAC cell proliferation, migration, and invasion in vitro; promoted apoptosis in vitro; and hindered tumor growth in vivo. Experiments on the mechanism identified ETS proto-oncogene 1 (ETS1) as a direct target gene of miR-769 in PDAC cells. Furthermore, ETS1 turned out to be upregulated in PDAC tissue samples, and the upregulation of ETS1 negatively correlated with miR-769 expression. Moreover, ETS1 knockdown simulated the tumor-suppressive effects of miR-769 overexpression on PDAC cells. Besides, ETS1 reintroduction attenuated the antitumor actions of miR-769 upregulation in PDAC cells. CONCLUSION: Our findings indicate that miR-769 performs tumor-suppressive functions in PDAC by directly targeting ETS1, and this miRNA may represent a potential therapeutic target for the development of anticancer therapies.