Induction of antigen-specific CTL and antibody responses in mice by a novel recombinant tandem repeat DNA vaccine targeting at mucin 1 of pancreatic cancer.

Purpose: Tandem repeat (TR) is the key epitope of mucin 1 (MUC1) for inducing cytotoxic T lymphocytes (CTL) to kill the tumor cells specifically. This study aimed to construct a new recombinant DNA vaccine based on single TR and to investigate the induced immune responses in mice.

Materials And Methods: After the synthesis of a recombinant human TR(rhTR)and the construction of the recombinant plasmid pcDNA3.1-TR/Myc-his (+) A (pTR plasmid), C57BL/6 (H-2(b)) mice were immunized with it (TR group, n = 15). Mice inoculated with the empty vector (EV group, n = 15) and normal saline (NS group, n = 15) were used as vector and blank control, respectively. Cytotoxic assay was carried out to measure the CTL activity. And indirect enzyme-linked immunosorbent assay (ELISA) was used to detect anti-TR-specific antibodies.

Results: TR group resulted in more efficient induction of CTL-specific cytolysis against TR polypeptide than both EV and NS groups (both P < 0.01). Vaccine-immunized mice had a higher equivalent concentration of anti-TR-specific antibodies (2,324 ± 238 μg/ml) than either of EV group (1,896 ± 533 μg/ml, P < 0.01) or NS group (1,736 ± 142 μg/ml, P < 0.01).

Conclusion: The novel recombinant TR DNA vaccine targeting at MUC1 of pancreatic cancer was constructed successfully, effectively expressing TR polypeptide in the transfected mammalian cells and inducing TR-specific CTL and antibody response.