STAT3 regulates OXPHOS in LSCs via transcriptional regulation of MYC. (A) Cartoon depiction of sorting scheme for LSCs. (B) Maximal respiratory capacity changes based on Seahorse Cell Mito Stress Test in LSCs isolated form 3 primary AML samples after treatment with 5 μM of STAT3i for 4 hours compared with vehicle control. (C) RNA-sequencing showing expression changes in the MYC targets pathway in LSCs isolated from 4 primary AML samples after treatment with 5 μM of STAT3i compared with vehicle control. (D) Expression data from BloodSpot showing differences in MYC expression in AML cells compared with hematopoietic stem cells (HSCs). CBF, core-binding factor; Complex, complex cytogenetics. (E) ChIP-PCR showing STAT3 binding to MYC promoter region. Data are shown as percent input and normalized to negative IgG control. AcH3 is used as a positive control (n = 3). (F) qPCR comparing MYC expression of LSCs treated with 5 μM of STAT3i for 4 hours compared with vehicle control. (G) Western blot comparing protein levels of Myc in LSCs treated with 5 μM of STAT3i for 4 hours compared with vehicle control. (H) Western blot showing Myc protein expression 48 hours after siRNA transfection. (I) Seahorse Cell Mito Stress Test showing changes in maximal respiratory capacity of 4 primary AML samples 48 hours after transfection of either siRNA against MYC or scramble control. Statistical analyses were performed using the Student t-test. P values are represented as follows: *P ≤ .05; **P ≤ .01; ***P ≤ .001; ****P ≤ .0001.