CircCCNB1 Knockdown Blocks the Progression of Cervical Cancer by Acting as Competing Endogenous RNA in the miR-370-3p/SOX4 Pathway.

OBJECTIVE: Cervical cancer is one of the leading causes of cancer-related death in women, which has been shown to be associated with the deregulation of circular RNAs (circRNAs). The aim of this study was to determine the role of circRNA cyclin B1 (circCCNB1) in cervical cancer.

METHODS: The expression of circCCNB1, microRNA-370-3p (miR-370-3p), and SRY-box transcription factor 4 (SOX4) mRNA was detected by quantitative real-time PCR (qPCR). Functional experiments, including colony formation assay, EdU assay, transwell assay and flow cytometry assay, were performed. Lactate production and glucose uptake were examined to assess glycolysis metabolism. The protein levels of glycolysis-related markers and SOX4 were detected by western blot. The interaction between miR-370-3p and circCCNB1 or SOX4 was verified by dual-luciferase reporter, RIP, and pull-down assay. Xenograft assay was performed to monitor the role of circCCNB1 in animal models.

RESULTS: CircCCNB1 was highly expressed in cervical cancer tissues and cells (squamous cell carcinoma and adenocarcinoma cells). The knockdown of circCCNB1 inhibited cell proliferation, migration, invasion and glycolysis metabolism, and induced cell apoptosis. CircCCNB1 functioned as miR-370-3p sponge to suppress miR-370-3p expression and function. Moreover, circCCNB1 inhibited the expression of miR-370-3p to increase the expression of SOX4. MiR-370-3p inhibition reversed the effects of circCCNB1 knockdown and thus promoted cell proliferation, migration, invasion and glycolysis. SOX4 overexpression reversed the effects of miR-370-3p restoration and thus promoted cell proliferation, migration, invasion and glycolysis.

CONCLUSION: CircCCNB1 knockdown blocks cervical cancer development by targeting the miR-370-3p/SOX4 pathway.