CircDDX42 Accelerates the Development of Pancreatic Cancer via miR-613/ID4/PI3K/AKT Axis

BACKGROUND: Pancreatic cancer (PC) is one of the fatal cancers globally. CircDEAD-box helicase 42 (circDDX42) has been reported to play an oncogenic role in many cancers. The purpose of our study was to explore the relationship between circDDX42 and PC development and the potential mechanism by which circDDX42 modulating the progression of PC. METHODS: The enrichment of circDDX42, miR-613 and inhibitor of DNA binding 4 (ID4) was determined by quantitative real-time polymerase chain reaction (qRT-PCR) in PC tissues and cells. The proliferation, apoptosis and metastasis of PC cells were examined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Western blot, flow cytometry and transwell migration and invasion assays, respectively. The binding sites between miR-613 and circDDX42 or ID4 were predicted by Starbase bioinformatic software, and dual-luciferase reporter assay was conducted to verify the combination between miR-613 and circDDX42 or ID4. Western blot was carried out to detect the abundance of ID4, p-phosphatidylinositol 3-kinase (p-PI3K), PI3K, p-AKT serine/threonine kinase (p-AKT) and AKT in PC cells. The in vivo role of circDDX42 was verified through using murine xenograft model. RESULTS: The level of circDDX42 was enhanced in PC tissues and cells compared with that in matching normal tissues and HPDE cells. CircDDX42 promoted the proliferation and metastasis and suppressed the apoptosis of PC cells. CircDDX42 could sponge miR-613, and miR-613 was negatively regulated by circDDX42 in PC cells. MiR-613 suppressed the progression of PC. ID4 was a direct target of miR-613. ID4 was inversely modulated by miR-613 and positively regulated by circDDX42 in PC cells. ID4 played an oncogenic role in the tumorigenesis of PC. CircDDX42/miR-613/ID4 axis regulated the activation of PI3K/AKT pathway in PC cells. ID4 facilitated the progression of PC via activating PI3K/AKT signal pathway. CircDDX42 promoted the tumor growth of PC in vivo. CONCLUSION: CircDDX42 accelerated the proliferation and metastasis while impeded the apoptosis of PC cells via circDDX42/miR-613/ID4/PI3K/AKT axis. This axis might be a promising target for PC therapy.