Amino acids are essential nutrients for both tumor growth and immune cell function. Cancer cells actively deplete intracellular and extracellular amino acid pools, and limited amino acid availability in the tumor microenvironment (TME) reinforces immunosuppression. Mitochondria are not merely adenosine triphosphate-producing organelles. Amino acid metabolism within mitochondria contributes to tumor progression and influences immune cell fate and effector function. These effects are mediated through biosynthetic precursor generation for lipid, nucleotide, and polyamine synthesis, maintenance redox homeostasis through glutathione and NAD+ metabolism, and regulation of gene expression through aryl hydrocarbon receptor signaling. In this review, we discuss four major mitochondrial amino acid metabolic pathways: glutamine-driven anaplerosis, serine/glycine-dependent one-carbon metabolism, arginine–ornithine metabolism, and tryptophan–kynurenine metabolism. We examine how these pathways are rewired in cancer cells, how they influence immune cell function through direct or mitochondria-associated mechanisms, and how such metabolic reprogramming promotes tumor progression while impairing antitumor immunity. Finally, we consider therapeutic strategies to improve cancer immunotherapy by targeting amino acid metabolism, including mitochondrial metabolic enzymes. This review may help guide the development of more effective metabolic biomarkers and mitochondria-based therapeutic strategies for cancer immunotherapy.
Ham et al. (Sun,) studied this question.