title: Chemoenzymatically synthesized multimeric Tn/STn MUC1 glycopeptides elicit cancer-specific anti-MUC1 antibody responses and override tolerance.
abstract: The MUC1 mucin represents a prime target antigen for cancer immunotherapy because it is abundantly expressed and aberrantly glycosylated in carcinomas. Attempts to generate strong humoral immunity to MUC1 by immunization with peptides have generally failed partly because of tolerance. In this study, we have developed chemoenzymatic synthesis of extended MUC1 TR glycopeptides with cancer-associated O-glycosylation using a panel of recombinant human glycosyltransferases. MUC1 glycopeptides with different densities of Tn and STn glycoforms conjugated to KLH were used as immunogens to evaluate an optimal vaccine design. Glycopeptides with complete O-glycan occupancy (five sites per repeat) elicited the strongest antibody response reacting with MUC1 expressed in breast cancer cell lines in both Balb/c and MUC1.Tg mice. The elicited humoral immune response showed remarkable specificity for cancer cells suggesting that the glycopeptide design holds promise as a cancer vaccine. The elicited immune responses were directed to combined glycopeptide epitopes, and both peptide sequence and carbohydrate structures were important for the antigen. A MAb (5E5) with similar specificity as the elicited immune response was generated and shown to have the same remarkable cancer specificity. This antibody may hold promise in diagnostic and immunopreventive measures.
authors.affiliation: Department of Medical Biochemistry and Genetics, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen, Denmark.
authors.forename: Anne Louise
authors.initials: AL
authors.lastname: Sørensen
authors.forename: Celso A
authors.initials: CA
authors.lastname: Reis
authors.forename: Mads A
authors.initials: MA
authors.lastname: Tarp
authors.forename: Ulla
authors.initials: U
authors.lastname: Mandel
authors.forename: Kavitha
authors.initials: K
authors.lastname: Ramachandran
authors.forename: Vasanthi
authors.initials: V
authors.lastname: Sankaranarayanan
authors.forename: Tilo
authors.initials: T
authors.lastname: Schwientek
authors.forename: Ros
authors.initials: R
authors.lastname: Graham
authors.forename: Joyce
authors.initials: J
authors.lastname: Taylor-Papadimitriou
authors.forename: Michael A
authors.initials: MA
authors.lastname: Hollingsworth
authors.forename: Joy
authors.initials: J
authors.lastname: Burchell
authors.forename: Henrik
authors.initials: H
authors.lastname: Clausen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000096:biosynthesis / Q000737:chemistry / Q000276:immunology*; D019496:Cancer Vaccines / Q000737:chemistry* / Q000276:immunology*; D002460:Cell Line; D006020:Glycopeptides / Q000096:biosynthesis / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D018396:Mucin-1 / Q000276:immunology*; D013379:Substrate Specificity
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; D019496:Cancer Vaccines; D006020:Glycopeptides; D018396:Mucin-1