SIX1 drives acute myeloid leukemia progression by reprogramming glycolytic metabolism and impairing CD8⁺ T-cell effector function

This study aimed to investigate the role of the homeobox gene SIX1 (sine oculis homeobox homolog 1) in acute myeloid leukemia (AML) progression and to explore its underlying metabolic and immunological mechanisms. SIX1 expression was examined in human bone marrow stromal cells (HS-5) and AML cell lines (HL-60, SKM-1, THP-1, KG-1, NB4, and MOLM13) using RT-qPCR. SIX1-knockdown and SIX1-overexpressing MOLM13 cells were generated by RNA interference and plasmid transfection, respectively. Cell cycle distribution, proliferation, and metabolic parameters, including intracellular glucose, lactate, and ATP levels, were assessed using flow cytometry, EdU incorporation, MTT assays, and ELISA. Mitochondrial content was analyzed by transmission electron microscopy. Peripheral blood mononuclear cells (PBMCs) from healthy donors were co-cultured with genetically modified MOLM13 cells under low-glucose conditions to evaluate T-cell proportions and cytokine production (IL-6, TNF-α, and IFN-γ). An AML mouse model was further established to assess the effects of SIX1 on T-cell composition and function by flow cytometry, while global metabolomics was applied to characterize metabolic reprogramming in vivo. SIX1 was significantly up-regulated in AML cells and promoted MOLM13 cell proliferation by enhancing glycolytic metabolism. Moreover, SIX1 suppressed CD8⁺ T-cell effector function both in vitro and in vivo and was associated with extensive alterations in amino acid, glucose, and lipid metabolism in AML mice. SIX1 facilitates AML progression by promoting glycolytic reprogramming in leukemia cells and potentially impairing CD8⁺ T-cell effector function through metabolic competition, highlighting SIX1 as a promising therapeutic target.