miR-224 is Critical for Celastrol-Induced Inhibition of Migration and Invasion of Hepatocellular Carcinoma Cells

Background/Aims: The molecular mechanisms of celastrol on hepatocellular carcinoma (HCC) cells migration and invasion ability is the major problem that prompted the study. Methods: We first evaluated the effect of celastrol on migration and invasion ability of HepG2 cells using transwell migration and matrigel invasion assays. Next, we assessed the effect of celastrol on NF-kappa B transcriptional activity in hepatocellular carcinoma cells using western blot and luciferase reporter assay. We also performed real-time PCR to measure miR-224, MMP-2 and MMP-9 expression. Western blot was used to measure protein expression of MMP-2 and MMP-9. Furthermore, we used miR-224 inhibitor to evaluate whether down-regulation of miR-224 expression can affect MMP-2 and MMP-9 expression. The binding ability of p65/NF-kappa B on the miR-224 promote has been assessed by chromatin immunoprecipitation and quantitative real-time PCR (ChIP-qPCR). Finally, we evaluated the effect of miR-224 on celastrol-induced anti-tumor activity using miR-224 precursor. Results: Celastrol significantly impaired migration and invasion of HepG2 cells and inhibited the activation of NF-kappa B and Akt in dose-dependent manner. IGF (the strong stimulator of Akt) inhibited the transcriptional activity of NF-kappa B in cells treated with celastrol. Besides, celastrol efficiently decreased the expression of miR-224 and protein expression of MMP-2 and MMP-9. ChIP-qPCR showed that p65/NF-kappa B binding to the miR-224 promoter sharply decreased after exposure to celastrol in time-dependent manner. Furthermore, inhibition of miR-224 expression can decrease MMP-9 protein level. Most importantly, miR-224 precursor can reverse the effect of celastrol on impairment of migration and invasion in HepG2 and Huh7 cells. Conclusion: Celastrol treatment inhibits migration and invasion of HCC cell and that the effect is partly due to NF-kappa B regulating miR-224 expression. Copyright (c) 2013 S. Karger AG, Basel