The construction of new immunopotentiating MUC1-VNTR-C144 DNA vaccine for pancreatic cancer

Abstract

Objective To construct new MUC1-VNTR-C144 DNA vaccine for pancreatic cancer and study both CTL responses and antibody responses specific to VNTR enhanced by the C144 gene. Methods DNA encoding the 144 amino acids of the N-terminus of HBV core gene was cloned and then inserted into the recombinant plasmid pcDNA3.1-VNTR/Myc-his( + ) A. C57BL/6 mice were randomly immunized intramusscularly into anterior tibialis muscle with 100 μg plasmid DNA encoding VNTR ( V group,n = 15) or VNTR/CI44 (VC group,n = 15). Mice injected with the plasmid pcDNA3.1-C144/ Myc-his( + ) A vector (C group, n = 15 ) were used as controls. Four weeks later, all mice were injected a-gain with the same solution as before. Two weeks after the last immunization, spleen cells were obtained and analyzed for cytotoxic activity 6 days after in vitro stimulation by the synthesized VNTR polypeptide (Calcein AM assay). Blood was collected for the ELISA assay of anti-VNTR antibodies. Results The specific CTL killing rate against VNTR polypeptide induced in the VC group (46.7±8.2)% was signifi-cantly higher than in the V group (34.8±3.1 ) % and the C group ( 12.9±1.2) % ( P < 0.01 ) ,indicating the C144 gene enhances the CTL response induced by the vaccine. However,CTL lysed much more VNTR positive EIA than VNTR negative EIA ( P < 0.01 ), while the anti-VNTR antibody VU 3C6 significantly restrained such activity ( P <0.01 ) ,which indicated the CTL response was specific to VNTR. The equiva-lent concentration of specific antibody against VNTR in the VC group (2810.2±308.3 ) mg/L was signif-icantly higher than the V group (2323.5±238.3) mg/L and the C group (2130.9±138.5) mg/L (P < 0.01 ),which implied that the C144 gene could enhance the antibody response induced by the vaccine. Conclusion The VNTR specific CTL response and antibody response induced in mice immunized with new MUCl-VNTR-C144 DNA vaccine for pancreatic cancer can be enhanced significantly by the C144 gene. Key words: Pancreatic carcinoma; DNA vaccine