title: Immunohistochemical study of the expression of MUC6 mucin and co-expression of other secreted mucins (MUC5AC and MUC2) in human gastric carcinomas.
abstract: To investigate the expression of MUC6 mucin in gastric carcinomas, we generated a novel monoclonal antibody (MAb CLH5) using an MUC6 synthetic peptide. MAb CLH5 reacted exclusively with the MUC6 peptide and with native and deglycosylated mucin extracts from gastric tissues. MAb CLH5 immunoreactivity was observed in normal gastric mucosa restricted to pyloric glands of the antrum and mucopeptic cells of the neck zone of the body region. In a series of 104 gastric carcinomas, 31 (29.8%) were immunoreactive for MUC6. The expression of MUC6 was not associated with histomorphological type or with clinicopathological features of the carcinomas. Analysis of the co-expression of MUC6 with other secreted mucins (MUC5AC and MUC2) in 20 gastric carcinomas revealed that different mucin core proteins are co-expressed in 55% of the cases. MUC6 was co-expressed and co-localized with MUC5AC in 45% and with MUC2 in 5% of the cases. Expression of MUC2 alone was observed in 25% of the cases. All carcinomas expressing MUC2 mucin in more than 50% of the cells were of the mucinous type according to the WHO classification. The co-expression of mucins was independent of the histomorphological type and stage of the tumors. In conclusion, we observed, using a novel well-characterized MAb, that MUC6 is a good marker of mucopeptic cell differentiation and is expressed in 30% of gastric carcinomas, independent of the clinicopathological features of the cases. Furthermore, we found that co-expression and co-localization of mucins in gastric carcinomas is independent of histomorphology and staging. Finally, we observed that intestinal mucin MUC2 is expressed as the most prominent mucin of the mucins tested in mucinous-type gastric carcinomas.
authors.affiliation: Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal.
authors.forename: C A
authors.initials: CA
authors.lastname: Reis
authors.forename: L
authors.initials: L
authors.lastname: David
authors.forename: F
authors.initials: F
authors.lastname: Carvalho
authors.forename: U
authors.initials: U
authors.lastname: Mandel
authors.forename: C
authors.initials: C
authors.lastname: de Bolós
authors.forename: E
authors.initials: E
authors.lastname: Mirgorodskaya
authors.forename: H
authors.initials: H
authors.lastname: Clausen
authors.forename: M
authors.initials: M
authors.lastname: Sobrinho-Simões
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D055271:Mucin 5AC; D055262:Mucin-2; D055272:Mucin-6; D009077:Mucins / Q000276:immunology / Q000378:metabolism*; D010446:Peptide Fragments / Q000276:immunology; D013274:Stomach Neoplasms / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; C524625:MUC2 protein, human; C524678:MUC5AC protein, human; C524734:MUC6 protein, human; C524626:Muc2 protein, mouse; C524679:Muc5ac protein, mouse; C524735:Muc6 protein, mouse; D055271:Mucin 5AC; D055262:Mucin-2; D055272:Mucin-6; D009077:Mucins; D010446:Peptide Fragments