Glutamine: a new strategy for targeted metabolic therapy in the tumor microenvironment.

In the tumor microenvironment, glutamine has a profound impact not only on the growth, metabolism, metastasis, and invasion of tumor cells but also on the survival and function of immune cells and the behavior of nonimmune cells. Given the limited amount of glutamine in the tumor microenvironment, there is a competitive relationship between tumor and nontumor cells. Owing to the metabolic reprogramming of tumor cells, many nutrients, including glutamine, are necessary for tumor cells to maintain their rapid growth and high metabolic demand. Therefore, tumor cells are in a superior position to compete for glutamine. These findings provide solid theoretical support for targeting glutamine metabolism for anticancer therapy. This review summarizes the importance and necessity of glutamine for tumor cells and nontumor cells in the tumor microenvironment. According to the mechanism of action of glutamine in tumor cells and the regulatory mechanism of related signaling pathways, the currently developed anticancer drugs that target glutamine metabolism are categorized on a scientific basis, and the importance of basic medicine applied in clinical medicine is emphasized. This review not only provides anticancer information for clinicians but also brings hope to cancer patients.