ABSTRACT
The expression, function and prognostic significance of epoxide hydrolase 2 (EPHX2) in hepatocellular carcinoma (HCC) were comprehensively analyzed through collecting HCC tissues and public database. The GEO and MitoCarta databases were used to identify the mitochondria-related differentially expressed genes (DEGs) in HCC. The Cancer Genome Atlas (TCGA) database was applied to analyze the expression levels of DEGs in HCC, including EPHX2 and its co-expressed genes. The R package was applied to draw the Kaplan-Meier survival curve and gene function enrichment analysis. The STRING database and GSEA software were used to analyze the protein-protein interaction (PPI) network and gene set enrichment analysis. qPCR and GEO database were applied to verify the expression level of EPHX2 in HCC. In the present study, a total of 15 mitochondria-related DEGs were identified in HCC. The expression of EPHX2 in HCC was significantly decreased compared to the normal liver tissues (P < 0. 01). The expression of EPHX2 was related to gender, tumor stage and grade in HCC, but not associated with age, T stage, et al in HCC. Moreover, compared with the patients with lower expression of EPHX2, patients with higher expression of EPHX2 had a better prognosis. EPHX2 was associated with fatty acid degradation. In addition, PPI results indicated that HAO1, AGXT, ACOX1, GSTκ1, SCP-2, CAT, CYP2C8, CYP2C9, CYP2B6, and CYP2J2 were co-expressed with EPXH2 in HCC. Furthermore, GSEA results showed that the group with lower expression of EPHX2 was positively correlated with the gene set of liver cancer cell proliferation and liver cancer recurrence. qPCR and GEO database results verified that the expression of EPHX2 was significantly decreased in HCC. The expression of EPHX2 was decreased in HCC, strongly suggesting that EPHX2 might function as a tumor suppressor gene in HCC. However, the potential mechanism of EPHX2 in HCC needs to be further verified.