title: Increased ACE in extrahepatic cholangiocarcinoma as a clue for activated RAS in biliary neoplasms.
abstract: OBJECTIVE
  Cholangiocarcinoma (CCA) is a primary neoplastic tumor of the epithelial lining of the biliary tree which carries a poor prognosis despite combined therapeutic strategies. Although the exact etiology remains obscure, it has been suggested that locally produced Angiotensin II (Ang II) in intrahepatic CCA tissues plays a key role in the proliferation and activation of CCA. In the present study, we aimed to analyze the relationship between the levels of circulating angiotensin converting enzyme (ACE), an important molecule of the renin-angiotensin system (RAS), and biliary disorders.
  
  
  METHODS
  The study group comprised 19 extrahepatic cholangiocarcinoma (EHCC) (16 patients with hilar, three patients with distal CCA), and 15 choledocolithiasis (CL) patients, with 15 controls. Median age of EHCC, CL and healthy controls were 67 (48-82), 65 (29-87) and 56 (23-74) respectively. ACE was measured by monitoring the alteration in absorbance at 340 nm of the hydrolysis of furylacrylolylphenylalanylglycylglycine (FAPGG) to FAP and GG on an analyzer. The ACE activity in the sample was determined by comparing the sample reaction rate to that obtained with the ACE calibrator.
  
  
  RESULTS
  Serum mean ACE levels were 56.6±27.4 U/L, 32.9±14.6 U/L and 28.6±10.6 U/L for patients with EHCC, CL and healthy controls, respectively. Serum ACE levels were significantly higher in patients with EHCC compared to CL and control groups. No significant differences with respect to ACE levels were observed between CL and control groups.
  
  
  CONCLUSIONS
  Circulating ACE in the context of RAS might be associated with EHCC development by creating a local environment enriched with cytokines and other growth factors that may promote cholangiocyte turnover.
authors.affiliation: Department of Gastroenterology, Turkiye Yuksek İhtisas Education and Research Hospital, Sihhiye, 06100 Ankara, Turkey. yavuzbeyaz@yahoo.com
authors.forename: Yavuz
authors.initials: Y
authors.lastname: Beyazit
authors.forename: Tugrul
authors.initials: T
authors.lastname: Purnak
authors.forename: Burak
authors.initials: B
authors.lastname: Suvak
authors.forename: Mevlut
authors.initials: M
authors.lastname: Kurt
authors.forename: Abdurrahim
authors.initials: A
authors.lastname: Sayilir
authors.forename: Turan
authors.initials: T
authors.lastname: Turhan
authors.forename: Adnan
authors.initials: A
authors.lastname: Tas
authors.forename: Serkan
authors.initials: S
authors.lastname: Torun
authors.forename: Tugrul
authors.initials: T
authors.lastname: Celik
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ibis
authors.forename: Ibrahim C
authors.initials: IC
authors.lastname: Haznedaroglu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001650:Bile Duct Neoplasms / Q000097:blood*; D001653:Bile Ducts, Intrahepatic; D018281:Cholangiocarcinoma / Q000097:blood*; D042883:Choledocholithiasis / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D007703:Peptidyl-Dipeptidase A / Q000097:blood*; D055815:Young Adult
chemical_list: D007703:Peptidyl-Dipeptidase A