title: The human epithelial carcinoma antigen recognized by monoclonal antibody AE3 is expressed on a sulfoglycolipid in addition to neoplastic mucins.
abstract: The term human epithelial carcinoma antigen (HCA) has been applied collectively to mucin-type high molecular weight (>1000kDa) glycoproteins that are over-expressed in epithelial cancers. Since the 1990s, over 40 monoclonal antibodies have been raised that recognize HCA. There has been evidence that the antigenic determinants are mostly carbohydrates, but details have been elusive. Here we have carried out carbohydrate microarray analyses of one of the monoclonal antibodies, AE3, that has been regarded the 'most carcinoma specific' in respect to its ability to detect HCA in sera of patients with epithelial cancers. The microarrays encompassed a series of 492 sequence-defined glycan probes in the form of glycolipids and neoglycolipids. We have thus established that the antigen recognized by antibody AE3 is a carbohydrate sequence distinct from the A, B, H, Lewis(a/b), Lewis(x/y) and T antigens, but that it is strongly expressed on the monosulfated tetra-glycosyl ceramide, SM1a, Galβ1-3GalNAcβ1-4(3-O-sulfate)Galβ1-4GlcCer. This is the first report of an anti-HCA to be characterized with respect to its recognition sequence and of the occurrence of the antigen on a glycolipid as well as on glycoproteins. Knowledge of a discrete glycan sequence as target antigen now opens the way to its exploration as a serologic cancer biomarker, namely to determine if the antigen elicits an autoantibody response in early non-metastatic cancer, or if it is shed and immunochemically detectable in more advanced disease.
authors.affiliation: Glycosciences Laboratory, Department of Medicine, Imperial College London, Northwick Park and St. Marks Campus, Watford Road, Harrow, Middlesex, UK.
authors.forename: Angelina S
authors.initials: AS
authors.lastname: Palma
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Robert A
authors.initials: RA
authors.lastname: Childs
authors.forename: Colin
authors.initials: C
authors.lastname: Herbert
authors.forename: Denong
authors.initials: D
authors.lastname: Wang
authors.forename: Wengang
authors.initials: W
authors.lastname: Chai
authors.forename: Ten
authors.initials: T
authors.lastname: Feizi
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000032:analysis / Q000276:immunology*; D002240:Carbohydrate Sequence; D006017:Glycolipids / Q000276:immunology*; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D009077:Mucins / Q000276:immunology*; D040081:Protein Array Analysis
chemical_list: D000911:Antibodies, Monoclonal; D015295:Antigens, Tumor-Associated, Carbohydrate; D006017:Glycolipids; D016056:Immunodominant Epitopes; D009077:Mucins; C011117:sulfoglycolipids