AbstractBackgroundGrowing evidences suggest that circular RNAs (circRNAs) are important factors in cancer progression. Nevertheless, the role of circRNAs in the progression of pancreatic ductal adenocarcinoma (PDAC) remains unclear.MethodsCircPTPRA was identified based on our previous circRNA array data analysis. Wound healing, transwell, and EdU assays were performed to investigate the effect of circPTPRA on the migration, invasion, and proliferation of PDAC cells in vitro. RNA pull‐down, fluorescence in situ hybridization (FISH), RNA immunoprecipitation (RIP), and dual‐luciferase reporter assays were conducted to verify the binding of circPTPRA with miR‐140‐5p. Subcutaneous xenograft model was constructed for in vivo experiment.ResultsCircPTPRA was significantly upregulated in PDAC tissues and cells compared to normal controls. Moreover, circPTPRA overexpression was positively correlated with lymph node invasion and worse prognosis in PDAC patients. In addition, overexpression of circPTPRA promoted PDAC migration, invasion, proliferation, and epithelial‐mesenchymal transition (EMT) in vitro and in vivo. Mechanistically, circPTPRA upregulates LaminB1 (LMNB1) expression by sponging miR‐140‐5p and ultimately promotes the progression of PDAC.ConclusionsThis study revealed that circPTPRA plays an important role in the progression of PDAC by sponging miR‐140‐5p. It can be explored as a potential prognostic marker and therapeutic target for PDAC.