Upregulated circRNA hsa_circ_0071036 promotes tumourigenesis of pancreatic cancer by sponging miR-489 and predicts unfavorable characteristics and prognosis

Abstract

Circular RNAs (circRNAs), the new stars of endogenous non-coding RNAs, are dysregulated in various tumors including pancreatic cancer. Here, we aimed to investigate the biological functions of hsa_circ_0071036 in the tumourigenesis and progression of pancreatic ductal adenocarcinoma (PDAC) and its clinical implications. The differential expression profile of circRNAs in 4 pairs of PDAC tissues was analyzed by microarray assay. Quantitative real-time PCR and fluorescence in situ hybridization (FISH) were utilized to determine the expression patterns and their clinical significance. Functional experiments <i>in vitro</i> and <i>in vivo</i> were performed to explore whether hsa_circ_0071036 functions as an oncogenic circRNA in PDAC. Mechanistically, RT-qPCR, dual luciferase reporter and RNA pull-down assays were conducted to identify the interaction between hsa_circ_0071036 and miR-489 in PDAC. Hsa_circ_0071036 was remarkably overexpressed in PDAC cell lines and tissue samples, which negatively correlated with miR-489 expression. Aberrant expression of hsa_circ_0071036 correlated with poor clinicopathological characteristics and prognoses of PDAC patients. Knockdown of hsa_circ_0071036 suppressed proliferation and invasion and induced apoptosis <i>in vitro</i>. Moreover, the <i>in vivo</i> xenograft model confirmed that silencing of hsa_circ_0071036 attenuated tumor growth. Mechanistic analyses indicated that hsa_circ_0071036 acted as an efficient miRNA sponge for miR-489 in PDAC. In summary, our study revealed that upregulated hsa_circ_0071036 promotes PDAC pathogenesis and progression by directly sponging miR-489, which implies an important role for this circRNA-miRNA functional network.