title: A 40-50kDa Glycoprotein Associated with Mucus is Identified as α-1-Acid Glycoprotein in Carcinoma of the Stomach.
abstract: OBJECTIVE
  Secreted gastric mucins are large O-glycosylated proteins of crude mucus gels which are aberrantly expressed in malignancy. An albumin associated 55-65kDa glycoprotein was previously shown in mucus gels in gastric cancer. The aim of this study was to investigate its expression and identification in human gastric tissue.
  
  
  METHODS
  Mucins were purified from crude mucus scrapings of 16 partial and 11 total resections and a rabbit polyclonal antibody was raised to the 55-65kDa glycoprotein. The location and expression of the glycoprotein was examined in normal gastric mucosa (n=20), intestinal metaplasia (n=18) and gastric cancer (n=27) tissue by immunohistochemistry. Mucins were analyzed by isoelectric focusing (IEF) on 2-D polyacrylamide gels. Identification of the 40-50kDa glycoprotein was by MALDI-TOF MS technique. Plasma levels were examined by Western blotting.
  
  
  RESULTS
  Extensive SDS-PAGE analysis gave a PAS positive glycoprotein in the 40-50kDa range, in patients with gastric cancer but not normals. It was expressed in parietal and columnar cells of normal gastric tissue and intestinal metaplasia respectively, and in 22 of 27 gastric cancer specimens. In 2-D PAGE stained with Coomassie Blue there were 3 spots positively identified as alpha-1-acid glycoprotein (AGP) by MALDI-TOF MS technique. PAS staining revealed a single bright spot in the same position but could not be identified. Preliminary measurements showed slightly higher levels of AGP in plasma of patients with gastric carcinoma.
  
  
  CONCLUSIONS
  AGP levels are increased in gastric tissue and in the plasma of those with carcinoma of the stomach.
authors.affiliation: 1. Department of Surgery, University of Cape Town, South Africa;
authors.forename: Nthato
authors.initials: N
authors.lastname: Chirwa
authors.forename: Dhirendra
authors.initials: D
authors.lastname: Govender
authors.forename: Bongani
authors.initials: B
authors.lastname: Ndimba
authors.forename: Zoe
authors.initials: Z
authors.lastname: Lotz
authors.forename: Marilyn
authors.initials: M
authors.lastname: Tyler
authors.forename: Eugenio
authors.initials: E
authors.lastname: Panieri
authors.forename: Delawir
authors.initials: D
authors.lastname: Kahn
authors.forename: Anwar S
authors.initials: AS
authors.lastname: Mall