Abstract:Background and Aims Previous studies demonstrated that miR-574-5p is closely associated with the prognosis of a variety of tumors. However, the relationship between miR-574-5p and hepatocellular carcinoma (HCC) has not been reported yet. Therefore, this study was designed to investigate the expression of miR-574-5p in HCC and its relationship with prognosis of the patients.Methods The expressions of miR-574-5p in 130 paired specimens of HCC and adjacent tissue as well as in HCC cell lines (HepG2 and MHCC-97H) and normal hepatic cell line (L-02) were detected by qRT-PCR method. After the optimal cut-off value of miR-574-5p expression level was determined from the survival data of the patients using X-tile software, the relations of miR-574-5p expression with the clinicopathologic factors and postoperative survival rates of the patients were analyzed. The influencing factors for the prognosis of HCC patients were determined. The target genes of miR-574-5p were predicted by TargetScan, and then were verified by dual-luciferase reporter assay and confirmed by Western blot analysis.Results The expression levels of miR-574-5p were significantly increased in HCC tissue than that in adjacent tissue, and increased in HCC cell lines than that in normal hepatic cell line (all P<0.05). The expression of miR-574-5p was significantly associated with TNM stage (P=0.002) and degree of differentiation (P=0.000). Both overall survival rate and tumor-free survival rate were significantly lower in patients with high miR-574-5p expression than those in patients with low miR-574-5p expression (both P<0.01). The results of univariate and multivariate analysis showed that high miR-574-5p expression (HR=4.101, 95% CI=1.348-8.968, P=0.03), stage III-IV (HR=5.403, 95% CI=1.266-13.860, P=0.02) and moderate/poor differentiation (HR=3.655, 95% CI=2.165-6.984, P=0.00) were independent risk factors for overall survival of HCC patients, and high miR-574-5p expression (HR=7.168, 95% CI=1.144-18.260, P=0.01) and stage III-IV (HR=7.436, 95% CI=1.123-20.916, P=0.00) were independent risk factors for disease-free survival of HCC patients. Targetscan software analysis showed that there was a direct binding site between FOG2 and miR-574-5p, and dual luciferase reporter gene assay showed that FOG2 was the target gene of miR-574-5p. Western blot analysis showed that the protein expression level of FOG2 in HCC tissue was lower than that in adjacent tissue, and Pearson correlation analysis showed that the miR-574-5p expression was negatively correlated with the protein expression of FOG2 in HCC tissue (r=-0.499, P<0.05).Conclusion The expression of miR-574-5p is generally increased in HCC. High miR-574-5p expression can be considered as a molecular marker for poor prognosis of HCC patients. MiR-574-5p may probably exert a tumor-promoting action through down-regulating its target gene FOG2.