title: Prognostic significance of the combined expression of neutral endopeptidase and dipeptidyl peptidase IV in intrahepatic cholangiocarcinoma patients after surgery resection.
abstract: OBJECTIVE
  The aim of this study was to investigate the relationship between the expression of neutral endopeptidase (NEP) and dipeptidyl peptidase IV (DPP IV) proteins, and the clinical significance of the two proteins in patients with intrahepatic cholangiocarcinomas (IHCC).
  
  
  METHODS
  Expression patterns and subcellular localizations of NEP and DPP IV proteins in 186 primary IHCC and 60 noncancerous liver tissue specimens were detected by immunohistochemistry.
  
  
  RESULTS
  Both the expression of NEP and DPP IV proteins in IHCC tissues were significantly higher than those in noncancerous liver tissues (both P<0.001). Of 186 patients with IHCC, 128 (68.82%) highly expressed both NEP and DPP IV proteins. In addition, the coexpression of NEP and DPP IV proteins was significantly associated with advanced tumor stage (P=0.009), positive lymph node metastasis (P=0.016) and distant metastasis (P=0.013), and the presence of recurrence (P=0.027). Moreover, Kaplan-Meier analysis showed that IHCC patients with high NEP expression, high DPP IV expression, and combined overexpression of NEP and DPP IV proteins all had poorer overall survival and early recurrence after surgery. Furthermore, Cox analysis suggested that NEP expression, DPP IV expression, and combined expression of NEP and DPP IV proteins were all independent prognostic markers for overall survival and recurrence-free survival in patients with IHCC.
  
  
  CONCLUSIONS
  Our data suggest, for the first time, that both the expression of NEP and DPP IV proteins may be upregulated in human IHCC tissues and the combined expression of NEP and DPP IV proteins may play important roles in progression and prognosis of patients with IHCC.
authors.affiliation: Department of Hepatobiliary Surgery, Navy General Hospital, PLA, Beijing, People's Republic of China.
authors.forename: Jianyong
authors.initials: J
authors.lastname: Zhu
authors.affiliation: 302 Hospital of PLA, Beijing, People's Republic of China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Hepatobiliary Surgery, Navy General Hospital, PLA, Beijing, People's Republic of China.
authors.forename: Baoan
authors.initials: B
authors.lastname: Qiu
authors.affiliation: 302 Hospital of PLA, Beijing, People's Republic of China.
authors.forename: Zhiyan
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Hepatobiliary Surgery, Navy General Hospital, PLA, Beijing, People's Republic of China.
authors.forename: Nianxin
authors.initials: N
authors.lastname: Xia
authors.affiliation: Department of Hepatobiliary Surgery, Navy General Hospital, PLA, Beijing, People's Republic of China.
authors.forename: Yingxiang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Hepatobiliary Surgery, Navy General Hospital, PLA, Beijing, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
keywords: clinicopathological characteristics; prognosis; tumor progression