ABSTRACT
Objective To investigate the role and implication of Engrailed-2 (EN2) in human hepatocellular carcinoma (HCC) and the effect of silencing EN2 genes on the proliferation and invasion of HepG2 cells by RNA interference.Methods Immunohistochemistry was used to detect the expression of EN2 in the HCC tissues and corresponding non-cancerous adjacent liver tissues in 126 patients with HCC.The expressions of EN2 and the relationship between EN2 expression and clinicopathological features and prognosis were analyzed using the Chi-square test.The survival curve was drawn using the Kaplan-Meier method and the survival was analyzed using the log-rank test.EN2-small interfering RNA (siRNA) was transfected into HepG2 cell lines mediated by LipofectamineTM 2000,and the expression of EN2 were detected by Western blotting assay.The cell proliferation and invasion were measured by methyl thiazol tetrazolium (MTT) and Transwell assays.Results EN2 positive expression rate was high (62.7％) in HCC tissue but low in the corresponding peritumoral tissue (23.5％,P ＜ 0.01).The high expression of EN2 was strongly correlated with tumor size,metastasis and AJCC TNM stage.The cumulative 5-year survival rate was 33.9％ in the low EN2 expression group,whereas it was 5.1％ in the high EN2 expression group (P ＜ 0.01).Expression of EN2 in EN2 siRNA group was significantly lower than that in control siRNA group and control group (P ＜ 0.05),respectively.The cell proliferation and invasion ability were significantly reduced in the EN2 siRNA group.Conclusion The expression of EN2 is highly up-regulated in HCC tissues and down-regulation of EN2 could inhibit proliferation and invasion of HepG2 cells,which indicating that EN2 is involved in the process of HCC carcinogenesis and progression and may serve as a biomarker for predicting prognosis of HCC patients.