Dual-targeting vaccine of FGL1/CAIX exhibits potent anti-tumor activity by activating DC-mediated multi-functional CD8 T cell immunity

Abstract

Tumor DNA vaccine as an effective therapeutic approach can induce systemic immunity against malignant tumors, but its therapeutic effect is still not satisfactory in advanced renal cancer. Herein, a novel DNA vaccine containing dual antigens of fibrinogen-like protein 1 (FGL1) and carbonic anhydrase IX (CAIX) was developed and intramuscularly delivered by PLGA/PEI nanoparticles for renal cancer therapy. Compared with PLGA/PEI-pCAIX immunization, PLGA/PEI-pFGL1/pCAIX co-immunization significantly inhibited the subcutaneous tumor growth and promoted the differentiation and maturation of CD11c+ DCs and CD11c+CD11b+ DCs subset. Likewise, the increased capabilities of CD8 T cell proliferation, CTL responses, and multi-functional CD8+ T cell immune responses were observed in PLGA/PEI-pFGL1/pCAIX vaccine group. Interestingly, depletion of CD8+ T cells by using CD8 mAb resulted in a loss of anti-tumor function of PLGA/PEI-pFGL1/pCAIX vaccine, suggesting that the anti-tumor activity of the vaccine was dependent on CD8+ T cell immune responses. Furthermore, PLGA/PEI-pFGL1/pCAIX co-immunization also suppressed the lung metastasis of tumor mice by enhancing the multi-functional CD8+ T cell responses. Therefore, these results indicate that PLGA/PEI-pFGL1/pCAIX vaccine could provide an effective protective effect for renal cancer by enhanced DC-mediated multi-functional CD8+ T cell immune responses. This vaccine strategy offers a potential approach for solid or metastatic tumor treatment.