CircRNF13 Promotes the Malignant Progression of Pancreatic Cancer through Targeting miR-139-5p/IGF1R Axis

BACKGROUND: Mounting evidence has shown circular RNAs (circRNAs) play an important role in the initiation and progression of pancreatic cancer (PC). Meanwhile, circRNAs may serve as the biomarkers for the diagnosis, treatment, and prognosis of PC. Therefore, it is urgent to elucidate the function and underlying mechanism of circRNAs in the development of PC. METHODS: The Cancer-Specific CircRNA Database (CSCD), Circular RNA Interactome database (circinteractome database), and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were used to verify the expression level of circRNF13 in PC cell lines. Fluorescence in situ hybridization (FISH) and RNase protection assay were used to detect the localization and structure of circRNF13. Then, cell functional experiments were employed to estimate the proliferated, migrated, and invasive abilities in PC. Furthermore, bioinformatic tools, luciferase dual reporter assay, and RT-qPCR were used to investigate the interaction among circRNF13, miR-139-5p, and IGF1R. Eventually, the rescue functional experiments were employed to confirm that circRNF13 targeted the miR-139-5p/IGF1R axis to participate in the development of PC. RESULTS: CircRNF13 was overexpressed in PC cell lines compared with the normal pancreatic duct cell line. Additionally, inhibition of circRNF13 impaired the proliferation, migration, and invasion of PC cells. CircRNF13 could serve as the molecular sponge of miR-139-5p to inhibit its association with IGF1R that eventually accelerated the malignant progression of PC. CONCLUSION: CircRNF13 serves as a competitive endogenous RNA of IGF1R to inhibit the function of miR-139-5p that eventually reinforces the malignant phenotype of PC.