Long-term tumor growth suppression in mice immunized with naked DNA of thehuman tumor antigen mucin (MUC1)

Naked DNA is an attractive toot for vaccination studies. We have studied na ked DNA vaccination, against the human tumor antigen mucin, encoded by the gene MUC1. C57/BL6 mice were immunized twice, on day I and day 10, with pla smid pCI-MUC1, intramuscularly. Five days after the last immunization tumor challenge experiments were performed using the tumor cell line MC38, expre ssing human MUC1. In 85% of mice immunized with the mucin plasmid tumor gro wth inhibition was observed, whereas control mice developed tumors. Re-tumo r challenge after three months revealed no tumor growth in mice immunized w ith the mucin plasmid. These encouraging results, showing long-term protect ion against tumor growth, indicate the potential usefulness of naked DNA va ccination for clinical immunotherapy.