PKM2 orchestrates tumor progression via metabolic reprogramming and MDSCs-mediated immune suppression in the tumor microenvironment.

The tumor microenvironment (TME) is a complex system, in which the energy metabolism of tumor cells plays a key role in the occurrence, development and metastasis of tumors. In the TME, the energy supply of tumor cells mainly comes from glycolysis. This metabolic reprogramming phenomenon is usually called the Warburg effect. Despite the abundance of oxygen, tumor cells still preferentially utilize the glycolytic pathway to meet their bioenergetic demands. Pyruvate kinase (PK), as a key enzyme in glycolysis, plays an important role in the regulation of energy metabolism in tumor cells. Among them, pyruvate kinase M2 (PKM2) is highly expressed in tumors and promotes the release of cytokines by tumor cells, thereby recruiting myeloid-derived suppressor cells (MDSCs). These cytokines bind to the surface receptors of MDSCs, activate related signaling pathways, and up-regulate the expression of cathepsin cysteine proteases. This process subsequently inhibits the activity of T cells, thereby affecting tumor development.