Puerarin Inhibits the Progression of Bladder Cancer by Regulating circ_0020394/miR-328-3p/NRBP1 Axis

Background: Previous studies have shown puerarin to be a potential therapeutic drug for treatment of bladder cancer. But the role and possible molecular mechanism of puerarin remain unknown. Methods: Cell viability, apoptosis, migration, and invasion were assessed by Cell Counting Kit-8 (CCK-8), flow cytometry, and transwell assays, respectively. Western blot was used to measure the levels of all protein. Glucose consumption and lactate production were detected using a glucose and lactate assay kit. Circular RNA_0020394 (circ_0020394), microRNA-328-3p (miR-328-3p), and nuclear receptor binding protein 1 (NRBP1) levels were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The interaction between miRNA and circRNA or mRNA was confirmed using dual-luciferase reporter assay. In vivo experiments were performed to examine the effect of puerarin on tumor growth. Results: Puerarin suppressed cell viability, migration, invasion, and glycolysis, and induced apoptosis in bladder cancer. circ_0020394 was downregulated in puerarin-treated bladder cancer cells, and circ_0020394 overexpression attenuated the inhibitory effect of puerarin on cell progression. Moreover, circ_0020394 could bind to miR-328-3p, and miR-328-3p directly targeted NRBP1. Functionally, miR-328-3p could reverse the promotion effect of circ_0020394 overexpression on the progression of puerarin-treated cells, and silencing NRBP1 counteracted the effects of anti-miR-328-3p on puerarin-treated cells. Mechanically, circ_0020394 could increase NRBP1 expression by acting as miR-328-3p sponge in puerarin-treated bladder cancer cells. Besides, puerarin inhibited tumorigenesis in vivo by increasing miR-328-3p and decreasing the levels of circ_0020394 and NRBP1. Conclusions: Puerarin impedes cell viability, migration, invasion, and glycolysis, and promoted apoptosis in bladder cancer by regulating circ_0020394/miR-328-3p/NRBP1 axis.