STAT3 regulates ETC activity of LSCs. (A) Bar graph representing complex activity of complexes I, II/III, and V in 3 primary AML samples after treatment with 5 μM STAT3i or vehicle control for 4 hours. (B) Complex II/II activity of 3 primary AML samples treated with 5 μM STAT3i or vehicle control for 4 hours. Cells were incubated on metabolomics media or in the presence of 4 mM glutamine and 4 mM cell-permeable α-KG. (C) Mitochondrial ROS as measured by flow cytometry in LSCs isolated from 3 primary AML samples and treated with 5 μM of STAT3i for 4 hours compared with vehicle control; 4 μM of cell-permeable GSH was used as positive control. (D) qPCR showing gene expression of ETC complex genes in LSCs isolated from 3 primary AML samples and treated with 5 μM of STAT3i for 4 hours or vehicle control. (E) Gene expression from RNA sequencing of mitochondrial genes in LSCs treated with 5 μM of STAT3i for 4 hours or vehicle control (n = 4). (F) Western blot showing protein levels of MT-CO1 and MT-ND2 in LSCs treated with or without 5 μM of STAT3i for 4 hours. Statistical analyses were performed using the Student t-test. P values are represented as follows: *P ≤ .05; **P ≤ .01; ***P ≤ .001; ****P ≤ .0001.