Studies On The Anti-cancer Activity And Mechanism Of HPV Therapeutic Fusion Protein Vaccine

Cervical cancer is a common female malignancy, for patients with advanced stage chemotherapy and surgery treatment are generally less effective. After it is discovered that cervical cancer is closely associated with HPV infection, many researchers put their focus on HPV vaccines study. Previously, our group successfully constructed mdNCRT/E7/hsp recombinant fusion protein vaccine targeting HPV 16, and proved through in vitro experiments that the vaccine could induce higher CTL activity and inhibit angiogenesis. The goal of this study is to further explore the anti-tumor efficacy in vivo and the possible molecular mechanisms involved in the immunotherapy.In the present study, we use C57BL/6 mice TC-1 tumor model, the in vivo study indicated that the recombinant fusion protein vaccine mdNCRT/E7/hsp was able to effectively inhibit tumor growth and induce tumor-specific rejection. The vaccine has therapeutic effect against HPV 16 E6E7-positive tumor growth in a mouse model. Immunohistochemical analysis was conducted on tumor tissue slices derived from control and experiment groups, respectively. The result reveals that mdNCRT/E7/hsp recombinant fusion protein can reduce tumor angiogenesis, decelerate tumor growth, and reduce the chance of metastatic infiltration.Next, Western blots were performed on two groups of tumor samples to investigate the molecular mechanisms that could be involved in the tumor growth inhibition function of mdNCRT/E7/hsp recombinant fusion protein vaccine. We find that:(1) IL-6/pStat3 signal transduction pathway:The results show that the expression levels of IL-6, p-Stat3, VEGF, HIF-1α, Snail in the vaccine group decreased significantly; the expression level of activated Caspase-3 increased markedly, which indicates that mdNCRT/E7/hsp recombinant fusion protein vaccine could inhibit angiogenesis and promote tumor cell apoptosis by inhibiting the gene expression of IL-6, pStat3 and its downstream protein; (2) MAPK-ERK signal transduction pathway: The results show that the expression level of B-raf, p-MEK, p-ERK in the vaccine group decreased, which indicates that mdNCRT/E7/hsp recombinant fusion protein vaccine could inhibit tumor growth by inhibiting the activities of the relevant MAPK kinase in MAPK-ERK signal transduction pathway chain.In conclusion, through blocking IL-6/pStat3 and MAPK-ERK signal transduction pathway, mdNCRT/E7/hsp recombinant fusion protein vaccine can inhibit tumor angiogenesis and metastatic infiltration, therefore producing anti-tumor effect.