Fig. 9.

Schematic diagram of the mechanistic findings. CXCR2 showed potent chemotaxis on neutrophils. Tumor microenvironment was abundant in immunosuppressive cytokines, such as TGF-β and Arg-1, which induced polarization of neutrophils to pro-tumor N2 type and impaired anti-tumor immune response. SB225002, a selective inhibitor of CXCR2, could effectively inhibit neutrophils infiltration to tumor microenvironment. Cisplatin, a common chemotherapy agent for lung cancer, could induce up-regulation of immunosuppressive markers, such as TGF-β, IL-10, and PD-L1 in tumor cells, which might contribute to reduced anti-tumor effect