title: Monoclonal antibodies toward different Tn-amino acid backbones display distinct recognition patterns on human cancer cells. Implications for effective immuno-targeting of cancer.
abstract: The Tn antigen (GalNAcα-O-Ser/Thr) is a well-established tumor-associated marker which represents a good target for the design of anti-tumor vaccines. Several studies have established that the binding of some anti-Tn antibodies could be affected by the density of Tn determinant or/and by the amino acid residues neighboring O-glycosylation sites. In the present study, using synthetic Tn-based vaccines, we have generated a panel of anti-Tn monoclonal antibodies. Analysis of their binding to various synthetic glycopeptides, modifying the amino acid carrier of the GalNAc(*) (Ser* vs Thr*), showed subtle differences in their fine specificities. We found that the recognition of these glycopeptides by some of these MAbs was strongly affected by the Tn backbone, such as a S*S*S* specific MAb (15G9) which failed to recognize a S*T*T* or a T*T*T* structure. Different binding patterns of these antibodies were also observed in FACS and Western blot analysis using three human cancer cell lines (MCF-7, LS174T and Jurkat). Importantly, an immunohistochemical analysis of human tumors (72 breast cancer and 44 colon cancer) showed the existence of different recognition profiles among the five antibodies evaluated, demonstrating that the aglyconic part of the Tn structure (Ser vs Thr) plays a key role in the anti-Tn specificity for breast and colon cancer detection. This new structural feature of the Tn antigen could be of important clinical value, notably due to the increasing interest of this antigen in anticancer vaccine design as well as for the development of anti-Tn antibodies for in vivo diagnostic and therapeutic strategies.
authors.affiliation: Departamento de Anatomía Patológica y Citología del Hospital de la Mujer, Centro Hospitalario Pereira Rossell, Montevideo, Uruguay.
authors.forename: Daniel
authors.initials: D
authors.lastname: Mazal
authors.forename: Richard
authors.initials: R
authors.lastname: Lo-Man
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bay
authors.forename: Otto
authors.initials: O
authors.lastname: Pritsch
authors.forename: Edith
authors.initials: E
authors.lastname: Dériaud
authors.forename: Christelle
authors.initials: C
authors.lastname: Ganneau
authors.forename: Andrea
authors.initials: A
authors.lastname: Medeiros
authors.forename: Luis
authors.initials: L
authors.lastname: Ubillos
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Obal
authors.forename: Nora
authors.initials: N
authors.lastname: Berois
authors.forename: Mariela
authors.initials: M
authors.lastname: Bollati-Fogolin
authors.forename: Claude
authors.initials: C
authors.lastname: Leclerc
authors.forename: Eduardo
authors.initials: E
authors.lastname: Osinaga
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000378:metabolism; D000918:Antibody Specificity / Q000276:immunology; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D005260:Female; D006020:Glycopeptides / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D009367:Neoplasm Staging; D009369:Neoplasms / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D011485:Protein Binding / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D015295:Antigens, Tumor-Associated, Carbohydrate; D014408:Biomarkers, Tumor; D006020:Glycopeptides; C040286:Tn antigen