Glycan bioengineering in immunogen design for tumor T antigen immunotargeting

Bioengineering of Gal beta 3GalNAc alpha, known as Thomsen-Friedenreich disaccharide (TIFID), is studied to promote glycan immunogenicity and immunotargeting to tumor T antigen (Gal beta 3GalNAc alpha-O-Ser/Thr). Theoretical studies on disaccharide conformations by energy minimization of structures using MM2 energy function showed that pentalysine (Lys5) linker and benzyl (Bzl) residue enhance TFD rigidity of the glycosidic bond. Antibodies raised against Bzl alpha TFD-Lys5 immunogen recognize tumor T antigen. Competitive assays confirm that TFID-related structures are the main glycan epitope. Antibodies produced by glycan bioengineering recognize HT29, T471), MCF7, and CT26 epithelial tumor cells. Epithelial tumor cell adhesion to T antigen-binding lectins and endothelial cells was lower in the presence of antibodies raised against the engineered immunogen. The immune response directed to the bioengineered glycoconjugate inhibited CT26 tumor cell proliferation and reduced tumor growth in an in vivo mouse model. These results show that TFD bioengineering is a useful immunogenic strategy with potential application in cancer therapy. The same approach can be extended to other glycan immunogens for immunotargeting purposes. (C) 2009 Elsevier Ltd. All rights reserved.