A Cell-Penetrating Peptide and Signal Sequence Fusion DNA Vaccine Enhances CD8+ T Cell-Mediated Anti-Tumor Immunity Targeting HPV-16 Cervical Cancer Antigens.

BACKGROUND: Cervical cancer is the fourth most common cancer affecting women, with almost all cases caused by infection with Human Papillomavirus (HPV). Previous research has explored the potential of cell-penetrating peptides to improve the efficacy of peptide vaccines and signal peptide sequences to increase protein secretion in DNA vaccines. In this study, we evaluated the in vivo efficacy of DNA vaccines targeting HPV-16 E6 and E7 viral antigens that are constructed with both a cell-penetrating peptide and IL-2 signal peptide to improve immunogenicity.

RESULTS: We generated DNA vaccine constructs utilizing combinations of E7(49-57), E6(48-57), IL-2 signal sequence (sig), 9-polyarginine (9R), and 12-polyarginine (12R) cloned into pcDNA3 vectors. Transfection of the pcDNA3-sig9RE7, pcDNA3-sig12RE7, or pcDNA3-9RE7 vaccine constructs induced a significant E7-specific CD8+ T cell response in vitro. We observed that the pcDNA3-sig9RE7 vaccine induced the strongest E7-specific immune response in vivo compared to the pcDNA3-9RE7 and pcDNA3-sig12RE7 constructs. We demonstrated the potential protective and therapeutic anti-tumor effects of the pcDNA3-sig9RE7 vaccination against the HPV-16 E7 expressing TC-1 tumor model in mice. Finally, we found similar anti-tumor effects for the pcDNA3-sig9RE6 vaccine which suggest this DNA vaccine strategy could be applied to various cervical cancer antigens.

CONCLUSION: Treatment with the pcDNA3-sig9RE7 DNA vaccine induces a potent E7-specific anti-tumor immune response in mice. By demonstrating the potential of utilizing a cell-penetrating peptide and signal peptide sequence in combination to improve efficacy, this study provides a foundation for future research into fusion DNA vaccines with cell-penetrating peptides and signal peptide combinations.