Silencing Circular RNA Hsa_circ_0000977 Suppresses Pancreatic Ductal Adenocarcinoma Progression by Stimulating MiR-874-3p and Inhibiting PLK1 Expression

Circular RNAs (CircRNAs) are a novel type of endogenous noncoding RNAs that regulate target gene expression by interacting with microRNA (miRNA). Emerging evidence shows that dysregulation of circRNAs plays important roles in biological and pathological processes, including cancer development and progression. The functional role of circRNA in PDAC (pancreatic ductal adenocarcinoma) remains to be investigated. In this study, high throughput microarray assay revealed that hsa_circ_0000977 was aberrantly up-regulated in pancreatic cancer tissues; this was also validated by qRT-PCR. Silencing hsa_circ_0000977 suppressed pancreatic cancer cell proliferation and induced cell cycle arrest, which was simulated by hsa-miR-874-3p mimics and blocked by hsa-miR-874-3p inhibitor. Bioinformatics analysis predicted that there is an hsa_circ_0000977/hsa-miR-874-3p/PLK1 (Polo like kinase 1) axis in pancreatic cancer progression. Dual-luciferase reporter system and FISH assay validated the direct interaction of hsa_circ_0000977, hsa-miR-874-3p, and PLK1. Western blot verified that inhibition of hsa_circ_0000977 decreased PLK1 expression. Furthermore, silencing hsa_circ_0000977 suppressed pancreatic cancer growth in vivo. Altogether, silencing hsa_circ_0000977 suppresses progression of pancreatic cancer by interacting with hsa-miR-874-3p and decreasing inhibiting PLK1 expression. Our results may provide a promising strategy for future diagnosis and treatment of pancreatic cancer.