MicroRNAs (miRNAs) are regulatory small non-coding RNAs that can regulate gene expression by binding to gene elements, such as the gene promotor 5?UTR, mainly in the 3?UTR of mRNA. One miRNA targets many mRNAs, which can be regulated by many miRNAs, leading to a complex metabolic network. In our study, we found that the expression level of miR-590-5p is higher in the human hepatocellular carcinoma cell line HepG2 than in the normal hepatocellular cell line L02. Downregulation of miR-590-5p inhibited proliferation and invasion of hepatocellular carcinoma cells (HCCs). We also showed that expression of TGF-beta RII, which has been regarded as a regulator of tumor proliferation, invasion, and migration in hepatocellular carcinoma, is regulated by miRNA-590-5p. In addition, miR-590-5p downregulated the expression of TGF- beta RII by targeting the 3?UTR of mRNA. We also found that downregulation of miR-590-5p was associated with an elevation of TGF-beta RII and inhibition of proliferation and invasion in HepG2 cells. Furthermore, overex-pression of miR-590-5p was associated with upregulation of TGF-beta RII and could promote proliferation and invasion in L02 cells. In conclusion, we determined that TGF-beta RII is a novel target of miRNA-590-5p. Thus, the role of TGF-beta RII in regulating proliferation and invasion of human HCCs is controlled by miR-590-5p. In other words, miR-590-5p promotes proliferation and invasion in human HCCs by directly targeting TGF-beta RII.

Keywords: HepG2, invasion, L02, miR-590-5p, proliferation, TGF-beta RII