ABSTRACT
The endothelial glycoprotein MUC1 is known to underlie alterations in cancer by means of aberrant glycosylation accompanied by changes in morphology. The heavily shortened glycans induce a collapse of the peptide backbone and enable accessibility of the latter to immune cells, rendering it a tumor-associated antigen. Synthetic vaccines based on MUC1 tandem repeat motifs, comprising tumor-associated 2,3-sialyl-T antigen, conjugated to the immunostimulating tetanus toxoid, are reported herein. Immunization with these vaccines in a simple water/oil emulsion produced a strong immune response in mice to which stimulation with complete Freund's adjuvant (CFA) was not superior. In both cases, high levels of IgG1 and IgG2a/b were induced in C57BL/6 mice. Additional glycosylation in the immunodominant PDTRP domain led to improved binding of the induced antisera to MCF-7 breast tumor cells, compared with that of the monoglycosylated peptide vaccine.
ABSTRACT
A MUC1 anticancer vaccine equipped with covalently linked divalent mannose ligands was found to improve the antigen uptake and presentation by targeting mannose-receptor-positive macrophages and dendritic cells. It induced much stronger specific IgG immune responses in mice than the non-mannosylated reference vaccine. Mannose coupling also led to increased numbers of macrophages, dendritic cells, and CD4+ T cells in the local lymph organs. Comparison of di- and tetravalent mannose ligands revealed an increased binding of the tetravalent version, suggesting that higher valency improves binding to the mannose receptor. The mannose-coupled vaccine and the non-mannosylated reference vaccine induced IgG antibodies that exhibited similar binding to human breast tumor cells.
Subject(s)
Cancer Vaccines/immunology , Dendritic Cells/metabolism , Macrophages/metabolism , Mannose/chemistry , Mucin-1/immunology , Animals , CD4-Positive T-Lymphocytes/cytology , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , Cancer Vaccines/metabolism , Dendritic Cells/cytology , Dendritic Cells/immunology , Enzyme-Linked Immunosorbent Assay , Humans , Immunoglobulin G/analysis , Immunoglobulin G/immunology , Immunoglobulin G/metabolism , Lectins, C-Type/metabolism , Ligands , Lymph Nodes , MCF-7 Cells , Macrophages/cytology , Macrophages/immunology , Mannose Receptor , Mannose-Binding Lectins/metabolism , Mice , Mice, Inbred BALB C , Mucin-1/chemistry , Mucin-1/metabolism , Protein Binding , Receptors, Cell Surface/metabolismABSTRACT
Breaking tolerance is crucial for effective tumor immunotherapy. We showed that vaccines containing tumor-associated human MUC1 glycopeptides induce strong humoral antitumor responses in mice. The question remained whether such vaccines work in humans, in systems where huMUC1 is a self-antigen. To clarify the question, mice transgenic in expressing huMUC1, mimicking the self-tolerant environment, and wild-type mice were vaccinated with a synthetic vaccine. This vaccine comprised STn and Tn antigens bound to a MUC1 tandem repeat peptide coupled to tetanus toxoid. The vaccine induced strong immune responses in wild-type and huMUC1-transgenic mice without auto-aggressive side effects. All antisera exhibited almost equivalent binding to human breast tumor cells. Similar increases of activated B-, CD4+ T-, and dendritic cells was found in the lymph nodes. The results demonstrate that tumor-associated huMUC1 glycopeptides coupled to tetanus toxoid are promising antitumor vaccines.
Subject(s)
Antigens, Tumor-Associated, Carbohydrate/therapeutic use , Breast Neoplasms/prevention & control , Cancer Vaccines/therapeutic use , Mucin-1/therapeutic use , Peptide Fragments/therapeutic use , Tetanus Toxoid/therapeutic use , Vaccines, Synthetic/therapeutic use , Animals , Antigens, Tumor-Associated, Carbohydrate/chemistry , Antigens, Tumor-Associated, Carbohydrate/immunology , Breast Neoplasms/immunology , Cancer Vaccines/chemistry , Cancer Vaccines/immunology , Female , Humans , Immunization , MCF-7 Cells , Mice, Inbred C57BL , Mice, Transgenic , Mucin-1/chemistry , Peptide Fragments/chemistry , Tetanus Toxoid/chemistry , Tetanus Toxoid/immunology , Vaccines, Synthetic/chemistry , Vaccines, Synthetic/immunologyABSTRACT
Fully synthetic MUC1 glycopeptide antitumor vaccines have a precisely specified structure and induce a targeted immune response without suppression of the immune response when using an immunogenic carrier protein. However, tumor-associated aberrantly glycosylated MUC1 glycopeptides are endogenous structures, "self-antigens", that exhibit only low immunogenicity. To overcome this obstacle, a fully synthetic MUC1 glycopeptide antitumor vaccine was combined with poly(inosinic acid:cytidylic acid), poly(I:C), as a structurally defined Toll-like receptorâ 3 (TLR3)-activating adjuvant. This vaccine preparation elicited extraordinary titers of IgG antibodies which strongly bound human breast cancer cells expressing tumor-associated MUC1. Beside the humoral response, the poly(I:C) glycopeptide vaccine induced a pro-inflammatory environment, very important to overcome the immune-suppressive mechanisms, and elicited a strong cellular immune response crucial for tumor elimination.
Subject(s)
Cancer Vaccines/immunology , Glycopeptides/immunology , Mucin-1/immunology , Poly I-C/immunology , Toll-Like Receptor 3/immunology , Vaccines, Synthetic/immunology , Adjuvants, Immunologic/chemistry , Adjuvants, Immunologic/genetics , Adjuvants, Immunologic/pharmacology , Animals , Cancer Vaccines/genetics , Cancer Vaccines/pharmacology , Dendritic Cells , Humans , Mice , Poly I-C/chemistry , Vaccines, Synthetic/genetics , Vaccines, Synthetic/pharmacologyABSTRACT
Self-adjuvanting antitumor vaccines by multifunctional cationic nanohydrogels loaded with CpG. A conjugate consisting of tumor-associated MUC1-glycopeptide B-cell epitope and tetanus toxin T-cell epitope P2 is linked to cationic nanogels. Oligonucleotide CpG complexation enhances toll-like receptor (TLR) stimulated T-cell proliferation and rapid immune activation. This co-delivery promotes induction of specific MUC1-antibodies binding to human breast tumor cells without external adjuvant.
Subject(s)
Adjuvants, Immunologic/pharmacology , Cancer Vaccines/immunology , Glycopeptides/immunology , Hydrogel, Polyethylene Glycol Dimethacrylate/chemistry , Nanoparticles/chemistry , Oligodeoxyribonucleotides/chemistry , Amino Acid Sequence , Animals , Cations , Enzyme-Linked Immunosorbent Assay , Glycopeptides/chemistry , Humans , Hydrogel, Polyethylene Glycol Dimethacrylate/chemical synthesis , Mice, Inbred BALB C , Molecular Sequence Data , Nanoparticles/ultrastructureABSTRACT
In a new concept of fully synthetic vaccines, the role of T-helper cells is emphasized. Here, a synthetic antitumor vaccine consisting of a diglycosylated tumor-associated MUC1 glycopeptide as the B-cell epitope was covalently cross-linked with three different T-helper-cell epitopes via squaric acid ligation of two linear (glyco)peptides. In mice this four-component vaccine administered without external immune-stimulating promoters elicit titers of MUC1-specific antibodies that were about eight times higher than those induced by a vaccine containing only one T-helper-cell epitope. The promising results indicate that multiple activation of different T-helper cells is useful for applications in which increased immunogenicity is required. In personalized medicine, in particular, this flexible construction of a vaccine can serve as a role model, for example, when T-helper-cell epitopes are needed that match human leukocyte antigens (HLA) in different patients.
Subject(s)
Antigens, Neoplasm/chemistry , Cancer Vaccines/chemical synthesis , Epitopes/chemistry , Glycopeptides/chemistry , Mucin-1/chemistry , T-Lymphocytes, Helper-Inducer/chemistry , Antigen-Antibody Reactions , Antigens, Neoplasm/immunology , Cancer Vaccines/chemistry , Cancer Vaccines/immunology , Epitopes/immunology , Glycopeptides/immunology , Humans , Molecular Structure , Mucin-1/immunology , T-Lymphocytes, Helper-Inducer/immunologyABSTRACT
For antitumor vaccines both the selected tumor-associated antigen, as well as the mode of its presentation, affect the immune response. According to the principle of multiple antigen presentation, a tumor-associated MUC1 glycopeptide combined with the immunostimulating T-cell epitope P2 from tetanus toxoid was coupled to a multi-functionalized hyperbranched polyglycerol by "click chemistry". This globular polymeric carrier has a flexible dendrimer-like structure, which allows optimal antigen presentation to the immune system. The resulting fully synthetic vaccine induced strong immune responses in mice and IgG antibodies recognizing human breast-cancer cells.