Synthesis And Immunological Evaluation Of Two-component Fluorinated MUC1 Tumor Vaccine

Overexpression of some abnormal sugar chains on the surface of cancer cells is called tumor-associated carbohydrate antigens(TACAs),which play an important role in the metastasis and signal transduction of cancer cells.Type I mucin(MUC1)provides suitable glycosylation sites for many cancer-related glycogen antigens,including Thomsen-Friedenreich(TF antigen).Due to the difference of surface glycogen antigens between tumor cells and normal cells,the vaccine targeting MUC1 glycopeptide epitope has become a research hotspot of anti-cancer vaccine because of its strong specificity and low toxicity.However,the weak immunogenicity of MUC1 glycogen itself has been restricting its development.On the one hand,because glycogen antigen is thymus independent antigen,it can only induce B cells to produce a lower intensity of immune response.Glycogen antigens can be linked to carrier proteins or T cell epitope peptides to produce a high-intensity immune response.On the other hand,glycogen antigens are endogenous substances,which are degraded and inactivated by glycosidases in vivo,thus reducing their immunogenicity.At present,scientists hope to solve this problem by non-natural modification of natural antigens.This paper designed a two-component vaccine of fluorinated TF antigen-MUC1 glycopeptide covalently linked to the peptide segment(YSYFPSV)on tetanus toxoid.Using galactose,galactosamine hydrochloride and threonine as starting reactants,6-position fluoro-substituted TF antigen-threonine block were synthesized in a total yield of 5%through 18 steps.Then,TF-threonine blocks were introduced into the synthesis of TF-MUC1 glycopeptide fragments by SPPS.Meanwhile,T helper cell epitope peptides were synthesized by solid-phase synthesis and activated by pentafluorophenyl ester.Finally,the target molecule was successfully obtained by coupling the fluorinated TF antigen-MUC1 glycopeptide with the T epitope peptide segment.In order to evaluate the immune activity of the vaccine,Balb/C mice were immunized three times.Blood samples were taken two weeks after the third immunization,and then serum antibody titers were determined by ELISA.The results showed that the titer of IgG antibody produced by two components of fluorinated MUC1 vaccine was 5173,and that of natural vaccine was 767,which was much lower than that of fluorinated vaccine.It was proved that the introduction of fluorine atoms greatly enhanced the immunogenicity of the vaccine.In conclusion,we have designed and successfully synthesized a fluorinated MUC1 two-component glycopeptide vaccine,which has stronger immune activity than the natural vaccine.This paper provides theoretical basis and data support for further design and synthesis of cancer vaccine.