MCT1 inhibition reprograms Treg metabolism via ABC transporters: implications for tumor immunity and the prognosis of acute myeloid leukemia patients

Glycolysis plays a critical role in regulatory T cells (Tregs), which are frequently exploited by tumor cells, as Treg survival depends on glycolytic activity to suppress antitumor immunity. However, the precise effects of glycolysis on Treg proliferation and differentiation remain incompletely understood. Monocarboxylate transporters (MCTs) are pivotal regulators of glycolytic flux. In this study, we investigated how MCT1 inhibition modulates Treg metabolism and function, and the potential implications for tumor immunotherapy. Silencing MCT1 in human primary Tregs using siRNA disrupted glycolysis, leading to G0/G1 cell cycle arrest, increased apoptosis, and ATP depletion. Integrated metabolomic and transcriptomic analyses identified the ABC transporter pathway as the most significantly altered, with coordinated changes in key genes (ABCA1, ABCB10, ABCC9, etc.) and the metabolite adenosine. Validation using The Cancer Genome Atlas (TCGA) acute myeloid leukemia cohort demonstrated that high expression of the ABC transporter gene ABCC9 is associated with improved overall survival (hazard ratio = 0.45, p < 0.001). These findings indicate that MCT1 inhibition is associated with alterations in the ABC transporter pathway, which may correlate with changes in Treg metabolism and the tumor immune microenvironment. Collectively, this work highlights metabolic reprogramming of Tregs as a novel therapeutic target for cancer immunotherapy.