Context-dependent roles of UCP2 in cancer: functional heterogeneity, molecular mechanisms and translational...

Uncoupling protein 2 (UCP2), a member of the solute carrier family 25 (SLC25) of mitochondrial carriers, is situated in the inner mitochondrial membrane and has conventionally been associated with proton leak, mitochondrial membrane potential, and control of reactive oxygen species (ROS). Recent research has expanded this perspective by establishing connections between UCP2 and C4 metabolite transport, glutamine utilization, tricarboxylic acid (TCA) cycle anaplerosis, and metabolic restructuring of the tumor immune microenvironment. Thus, the significance of UCP2 in cancer surpasses the traditional role of an energy-dissipating protein. Present data suggest that UCP2 exhibits context-specific roles across various cancer types. In certain contexts, it facilitates tumor adaptation by preserving redox balance, supporting glutamine metabolism, and enhancing metabolic flexibility under therapeutic pressure. Conversely, in different cancer types or immune-cell environments, UCP2 expression correlates with unique prognostic trends, treatment outcomes, or immune infiltration characteristics. This review outlines UCP2 biology with a focus on context specificity, highlighting its expression patterns across different cancers, metabolic alterations, redox regulation, intercellular signaling, and the tumor immune milieu. Furthermore, we explore the translational implications of UCP2 as both a biomarker and a therapeutic target. In essence, UCP2 should be regarded as a metabolic vulnerability that necessitates classification based on cancer type, mutational profile, metabolic requirements, and immune status, rather than as a universal target for broad-spectrum cancer inhibition.