Magnesium Isoglycyrrhizinate Suppresses the Progression of Bladder Cancer by Modulating miR-26b/Nox4 Axis

Abstract

Background: Magnesium Isoglycyrrhizinate (MI), a magnesium salt of 18α-GA stereoisomer, has been reported to exert efficient hepatoprotective activity. However, its effect in bladder cancer remain unclear.Methods: The effect of MI in the growth, colony formation, apoptosis, invasion and migration of bladder cancer cells (HTB9 and BIU87 cells) was evaluated in vitro. Typical apoptotic changes of bladder cancer cells such as nuclear concentration and fragmentation was observed by Hoechst staining. The effect of MI in the expression of miR-26b, Nox4, NF-κB and HIF-1α was detected by qRT-PCR and western blot in vitro. Targetscan was used to predict the potential targets of miR-26b, then their interaction was determined by the luciferase reporter assay. Finally, the xenograft model of mice was established to evaluate the anti-tumor effects of MI in vivo. Results: MI significantly suppressed the proliferation, colony formation, invasion, migration and induced apoptosis of human bladder cancer cells. Nox4 was identified to be a direct target of miR-26b, and MI significantly increased the expression of miR-26b. MiR-26b mimics significantly decreased the relative luciferase activity of wild type (WT) Nox4, while exhibited no obvious change in mutant type (MUT) Nox4. Meanwhile, MI markedly downregulated the expression of Nox4, NF-κB and HIF-1α both in vitro and in vivo. Moreover, MI could efficiently inhibit the growth of xenograft tumor in vivo, and also obviously decreased the expression of Nox4, NF-κB and HIF-1α. Conclusion: In summary, MI showed a potent anti-tumor effect against bladder cancer partially through modulating miR-26b/Nox4 axis.