[Interleukin-33: Friend or Enemy in the Fight against Tumors?]

Interleukin-33 (IL-33) belongs to the IL-1 cytokine family and acts as a danger signal. IL-33 is released from stressed or necrotic cells. Initially, IL-33 was described as an inducer of the humoral immune response, which activated Th2 cells and mast cells involved in modulating inflammation and allergic reactions. In addition, IL-33 acts as a stimulator of the Th1, NK, and CD8T cells, which induce a cytotoxic immune response against intracellular pathogens. It was recently discovered that this cytokine is involved in the development of cancer by performing both pro- and antitumor functions. IL-33 can directly affect tumor cells and provokes their proliferation, survival, and metastasis. Moreover, IL-33 stimulates carcinogenesis by remodeling the tumor microenvironment and inducing angiogenesis, thus contributing to the generation of immunosuppressive conditions. At the same time, IL-33 causes tumor infiltration with cytotoxic CD8 T lymphocytes and natural killers, which leads to cytolysis-mediated cancer cell death. This review describes the versatile role of the IL-33/ST2 cascade in the development of experimental and clinical tumors. In addition, we discuss the prospects for the application of IL-33 and ST2 as diagnostic biomarkers and targets for cancer immunotherapy.