Abstract: Objective To investigate the implication of neutral endopeptidase （NEP） and dipeptidyl peptidase（DPP） Ⅳ in hepatocellular carcinoma tissues. Methods Cancerous tissues were obtained from 42 patients with hepatocellular carcinoma （HCC） after hepatectomy，and 42 benign liver tissues at the same time were also obtained for control in the Department of Hepatobiliary Surgery，Beijing 301st Hospital between January 2008 and July 2013. The expression of NEP and DPP Ⅳin cancerous tissues were detected by immunohistochemical staining. Patients were checked-up every 3 months after operation. Kaplan-Meier method was used to draw the recurrence-free survival （RFS） curves and overall survival （OS） curves. Cox proportional hazards regression multivariate analysis was performed to determine the influencing factors of RFS and OS. Results NEP and DPP Ⅳ proteins were both located in the cytoplasm of hepatocellular carcinoma cells；The positive rates of NEP protein，DPP Ⅳ protein and double NEP and DPP Ⅳ protein in patients with hepatocellular carcinoma were 78.6%（33/42），71.4%（30/42） and 54.8%（23/42），respectively，all significantly higher than in normal liver tissues[2.4%（1/42），4.8%（2/42） and 0.0%（0/42），P<0.05]；Multivariate analysis demonstrated that tumor differentiation，NEP expression，DPP Ⅳ expression，NEP and DPPⅣ co-expression，recurrence and metastasis of cancer were the prognostic factors of RFS and OS in patients with HCC；The survival curves showed that RFS and OS were significantly shortened and the prognosis was poorer in patients with NEP or DPP Ⅳ or both of them positive in cancerous tissues. Conclusion The expression of NEP and DPP Ⅳ might be the risk factors for the poor prognosis in patients with HCC.

Key words: Hepatocellular caicinoma, Neutral endopeptidase, Dipeptidyl peptidase Ⅳ, Immunohistochemical staining, Prognosis