title: Identification of new cancer biomarkers based on aberrant mucin glycoforms by in situ proximity ligation.
abstract: Mucin glycoproteins are major secreted or membrane-bound molecules that, in cancer, show modifications in both the mucin proteins expression and in the O-glycosylation profile, generating some of the most relevant tumour markers in clinical use for decades. Thus far, the identification of these biomarkers has been based on the detection of either the protein or the O-glycan modifications. We therefore aimed to identify the combined mucin and O-glycan features, that is, specific glycoforms, in an attempt to increase specificity of these cancer biomarkers. Using in situ proximity ligation assays (PLA) based on existing monoclonal antibodies directed to MUC1, MUC2, MUC5AC and MUC6 mucins and to cancer-associated carbohydrate antigens Tn, Sialyl-Tn (STn), T, Sialyl-Le(a) (SLe(a)) and Sialyl-Le(x) (SLe(x)) we screened a series of 28 mucinous adenocarcinomas from different locations (stomach, ampulla of Vater, colon, lung, breast and ovary) to detect specific mucin glycoforms. We detected Tn/STn/SLe(a)/SLe(x)-MUC1 and STn/SLe(a)/SLe(x)-MUC2 glycoforms in ≥50% of the cases, with a variable distribution among organs. Some new glycoforms-T/SLe(a)-MUC2, STn/T/SLe(a) SLe(x)-MUC5AC and STn/T/SLe(a)/SLe(x)-MUC6-were identified for the first time in the present study in a variable percentage of cases from different organs. In conclusion, application of the PLA technique allowed sensitive detection of specific aberrant mucin glycoforms in cancer, increasing specificity to the use of antibodies either to the mucin protein backbone or to the O-glycan haptens alone.
authors: Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal.
authors: Rita
authors: R
authors: Pinto
authors: Ana S
authors: AS
authors: Carvalho
authors: Tim
authors: T
authors: Conze
authors: Ana
authors: A
authors: Magalhães
authors: Gianfranco
authors: G
authors: Picco
authors: Joy M
authors: JM
authors: Burchell
authors: Joyce
authors: J
authors: Taylor-Papadimitriou
authors: Celso A
authors: CA
authors: Reis
authors: Raquel
authors: R
authors: Almeida
authors: Ulla
authors: U
authors: Mandel
authors: Henrik
authors: H
authors: Clausen
authors: Ola
authors: O
authors: Söderberg
authors: Leonor
authors: L
authors: David
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000378:metabolism / Q000473:pathology; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000032:analysis / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000032:analysis*; D001940:Breast / Q000473:pathology; D018395:CA-19-9 Antigen; D003106:Colon / Q000473:pathology; D005455:Fluorescent Antibody Technique; D005732:Gangliosides / Q000032:analysis / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007150:Immunohistochemistry; D008168:Lung / Q000473:pathology; D055271:Mucin 5AC / Q000032:analysis*; D018396:Mucin-1 / Q000032:analysis*; D055262:Mucin-2 / Q000032:analysis*; D055272:Mucin-6 / Q000032:analysis*; D009369:Neoplasms / Q000175:diagnosis* / Q000473:pathology; D009844:Oligosaccharides / Q000032:analysis / Q000378:metabolism; D000080506:Sialyl Lewis X Antigen
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; D014408:Biomarkers, Tumor; D018395:CA-19-9 Antigen; D005732:Gangliosides; C060192:MUC1 protein, human; C524625:MUC2 protein, human; C524678:MUC5AC protein, human; C524734:MUC6 protein, human; D055271:Mucin 5AC; D018396:Mucin-1; D055262:Mucin-2; D055272:Mucin-6; D009844:Oligosaccharides; D000080506:Sialyl Lewis X Antigen; C040286:Tn antigen; C055491:sialosyl-Tn antigen; C064564:sialyl Le(a) ganglioside