Fig. 4

Diagram of the tumor microenvironment showing representative cell types, signaling factors, and various cytokines, as well as their mechanisms of action. At the tumor site, immune cells typically obtain tumor-related immunosuppressive phenotypes, except for cytotoxic CD8⁺lymphocytes (CTLs) that kill cancer cells. Myeloid-Derived Suppressor Cells (MDSCs) suppress immunity through various mechanisms. MDSCs can also induce T regulatory (Treg) cells, inhibit natural killer (NK) cells, and promote Tumor-Associated Macrophages (TAMs) with type 2 phenotype. Fibroblasts become Cancer-Associated Fibroblasts (CAFs), promoting extracellular matrix (ECM) remodeling. The extracellular vesicles released by various cells contain proteins, mRNA, and microRNAs that affect the microenvironment. Fibrotic cytokines recruit immune cells. Neutrophil Extracellular Traps (NETs) released by neutrophils after being stimulated can capture cancer cells. TAMs, TANs, and CAFs release angiogenic cytokines and Matrix Metalloproteinases (MMPs), promoting angiogenesis and ECM degradation, and promoting potential metastasis. In addition, the effects of cytokines are represented by red (tumor-promoting) and blue (anti-tumor) rectangles. Some cytokines, such as transforming growth factor- β (TGF-β), can have a dual effect, serving as both an anti-tumor factor and a tumor promoting factor depending on the situation. Created with BioRender.com