Sambucus adnata Polysaccharide SPS-1 Inhibits Growth of Transplanted Lung Cancer via Polarizing Tumor Associated Macrophage From M2 into M1

Abstract

Macrophages are the primary immune cells in the tumor microenvironment, where they exhibit the immunosuppressive M2 phenotype to support tumor development. Reshaping M2 tumor-associated macrophages (TAMs) into the antitumor M1 phenotype is a promising approach in tumor immunotherapy. We had previously demonstrated that a high-purity homogeneous Sambucus adnata wall polysaccharide SPS-1 isolated from S. adnata exerted a good immunoregulatory effect. In the present study, we explored whether SPS-1 can remodel TAMs and inhibit the development of lung cancer. In the tumor mouse model transplanted with Lewis lung cancer, SPS-1 promoted the apoptosis of tumor cells and inhibited angiogenesis in tumor tissues by remodeling M2 macrophages in the tumor microenvironment into M1 macrophages, which exerted effective antitumor effects. Therefore, SPS-1 may be used as a novel immunostimulator in tumor immunotherapy, and our study also provides a novel pathway and material for reshaping immune defense to prevent and treat tumors.