MicroRNA-455 regulates migration and invasion of human hepatocellular carcinoma by targeting Runx2

MicroRNA-455 (miR-455) has been considered as a novel cancer-related miRNA and dysregulated expression frequently occurs in various human types of cancer. However, its clinical significance, its biological function and the underlying molecular signaling involved in hepatocellular carcinoma (HCC) remain to be elucidated. In the present study, we found that the expression level of miR-455 was significantly downregulated in both HCC tissues and cell lines. Low expression of miR-455 was significantly associated with poor prognostic features including multiple tumor nodes, high Edmondson-Steiner grading, advanced tumor-node-metastasis (TNM) stage and venous infiltration. In addition, our data revealed that miR-455 was a novel prognostic indicator for predicting the 5-year overall and disease-free survival of HCC patients. The gain- and loss-of-function studies revealed that miR-455 significantly suppressed migration and invasion of HCC cells in vitro. miR-455 was inversely correlated with runt-related transcription factor 2 (Runx2) expression in HCC samples. Moreover, we identified that miR-455 inversely regulated Runx2 expression in HCC cells. In this investigation, Runx2 was found to be a direct downstream target of miR-455. Evidently, alteration in Runx2 expression suppressed the effect of miR-455 on HCC cell migration and invasion. In conclusion, our data demonstrated that miR-455 promotes HCC growth by targeting Runx2 and can potentially be regarded as a novel prognostic indicator and valuable therapeutic strategy for HCC.