title: Characterization of gastrins and their receptor in solid human gastric adenocarcinomas.
abstract: OBJECTIVE
  The gastrin and the gastrin/CCK-B receptor genes are co-expressed in several carcinomas. The primary translational product, progastrin, however, is processed to several peptides of which only those that are α-amidated at their C-terminus are receptor ligands. So far, characterization of the progastrin-derived peptides in gastric cancer has not been reported. The authors therefore examined the molecular nature of gastrin and its receptor in human gastric carcinomas.
  
  
  METHODS
  Twenty patients with adenocarcinoma underwent partial or total gastrectomy. In samples from each carcinoma, gastrin peptides were characterized, using a library of sequence-specific immunoassays. Expression was also demonstrated by immunohistochemistry. In addition, the gastrin and gastrin/CCK-B receptor gene expression was quantitated using real-time PCR, and the receptor protein demonstrated by western blotting.
  
  
  RESULTS
  α-Amidated gastrins were detectable in 16 of 20 carcinomas (median concentration 2.1 pmol/g tissue; range 0-386 pmol/g tissue). The tissue concentrations correlated closely to the gastrin mRNA contents (r = 0.75, p < 0.0001). Moreover, progastrin and non-amidated processing intermediates, including glycine-extended gastrins, were detected in 19 carcinomas. Immunohistochemistry corroborated gastrin expression in carcinoma cells. Chromatography revealed extensive progastrin processing with α-amidated gastrin-34 and -17 (tyrosyl-sulfated as well as non-sulfated) as major products. Finally, gastrin/CCK-B receptor mRNA and protein were detected in all tumors.
  
  
  CONCLUSIONS
  The results show that the elements for a local loop of α-amidated gastrins and their receptor are detectable in 80% of human gastric adenocarcinomas. Therefore, the results support the contention that locally expressed gastrin may be involved in the tumorigenesis of gastric adenocarcinomas.
authors.affiliation: Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Goetze
authors.forename: Signe
authors.initials: S
authors.lastname: Eiland
authors.forename: Lars Bo
authors.initials: LB
authors.lastname: Svendsen
authors.forename: Ben
authors.initials: B
authors.lastname: Vainer
authors.forename: Jens
authors.initials: J
authors.lastname: Hannibal
authors.forename: Jens Frederik
authors.initials: JF
authors.lastname: Rehfeld
mesh_terms: D000230:Adenocarcinoma / Q000737:chemistry* / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005755:Gastrins / Q000032:analysis / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D008297:Male; D008875:Middle Aged; D011498:Protein Precursors / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D043887:Receptor, Cholecystokinin B / Q000032:analysis* / Q000235:genetics; D013274:Stomach Neoplasms / Q000737:chemistry* / Q000235:genetics*
chemical_list: D005755:Gastrins; D011498:Protein Precursors; D012333:RNA, Messenger; D043887:Receptor, Cholecystokinin B; C086854:glycine-extended gastrin 17; C013706:big gastrin; C013550:gastrin 17