SHISA3 reprograms tumor-associated macrophages toward an M1 phenotype and enhances cancer immunotherapy

The main challenge for immune checkpoint blockade (ICB) therapy lies in immunosuppressive tumor microenvironment (TME). Repolarizing M2-like tumor-associated macrophages (TAMs) into inflammatory M1 phenotype is a promising strategy for cancer immunotherapy. Here, we found that the transmembrane protein SHISA3 is induced by DAMPs/PAMPs in macrophages via nuclear factor-κB (NF-κB) transcription factors, and SHISA3 forms complex with HSPA8 to reciprocally activates NF-κB signaling thus maintains M1 polarization of macrophages. Enforced expression of Shisa3 in TAMs increases their phagocytosis and antigen presentation abilities and promotes CD8+ T cell-mediated antitumor immunity. Local delivery of mRNA encoding Shisa3 enables therapy of cancer by dual effects on tumor cells and TAMs, and enhance the efficacy of PD-1 antibody. Taken together, our findings describe the role of SHISA3 in reprogramming TAMs that ameliorates cancer immunotherapy To find new molecules that regulate macrophage polarization, we performed transcriptomic analysis on early macrophages polarization induced by LPS for 0, 2, 4 hours.