Abstract: AIM: To observe the inhibiting effect of the GRP DNA vaccine on EMT6 breast cancer tissue. METHODS: Female BALB c mice were immunized intramuscularly with GRP DNA vaccine pCR3. 1-VS-HSP65- TP-GRP6-M2 5 times at 2-weekly intervals. The specific anti-GRP antibody was detected by ELISA method. Two weeks after the last immunization, tumor challenge experiments were performed by using EMT6. After 14 d of challenge experiments, all mice were killed and tumors were weighted. Histological analysis of tumor tissue was carried out with HE staining. RESULTS: The specific anti-GRP antibodies were detected in the antiserum of the female BALB c mice immunized with pCR3. 1-VS-HSP65-TPGRP6- M2 DNA vaccine. It showed that EMT6 tumor growth in mice of GRP DNA vaccine group was obviously suppressed (P<0.01) compared with that in pCR3. 1- VS-HSP65-TP or saline control group, with tumor inhibitory rate of 46. 53 %. Histological analysis showed that GRP DNA vaccine successfully induced anti-tumor immune responses in vivo, and, the invasiveness of EMT6 tumor tissues was markedly decreased in mice of GRP DNA vaccine group compared with that in pCR3. 1-VSHSP65- TP control group. CONCLUSION: GRP DNA vaccine can significantly suppress the growth of EMT6 breast cancer in vivo, which lays a basis for further research.

Key words: gastrin-releasing peptide, DNA vaccine, breast cancer, tumor inhibitory rate