In human pancreatic
adenocarcinoma, alterations of glycosylation processes leads to the expression of
tumor-associated carbohydrate antigens, representing potential targets for
cancer immunotherapy. Among these pancreatic
tumor-associated carbohydrate antigens, the J28 glycotope located within the O-glycosylated
mucin-like C-terminal domain of the fetoacinar pancreatic
protein (FAPP) and expressed at the surface of human tumoral tissues, can be a good target for anticancer therapeutic
vaccines. However, the oncodevelopmental self character of the J28 glycotope associated with the low immunogenicity of
tumor-associated carbohydrate antigens may be a major obstacle to effective anti-
tumor vaccine therapy. In this study, we have investigated a method to increase the immunogenicity of the recombinant pancreatic oncofetal J28 glycotope by glycoengineering Galalpha1,3Galss1,4GlcNAc-R (alphaGal
epitope) which may be recognized by natural anti-alphaGal antibody present in humans. For this purpose, we have developed a stable Chinese hamster ovary cell clone expressing the alphaGal
epitope by transfecting the
cDNA encoding the alpha1,3galactosyltransferase. These cells have been previously equipped to produce the recombinant O-glycosylated C-terminal domain of FAPP carrying the J28 glycotope. As a consequence, the C-terminal domain of FAPP produced by these cells carries the alphaGal
epitope on
oligosaccharide structures associated with the J28 glycotope. Furthermore, we show that this recombinant "alpha1,3galactosyl and J28 glycotope" may not only be targeted by human natural anti-alphaGal
antibodies but also by the mAbJ28, suggesting that the J28 glycotope remains accessible to the immune system as vaccinating agent. This approach may be used for many identified
tumor-associated carbohydrate antigens which can be glycoengineered to carry a alphaGal
epitope to increase their immunogenicity and to develop therapeutic
vaccines.