Meis1 regulates oxidative stress and oxygen flux in leukemia. (A) Representative histograms of intracellular ROS (DCFDA) in MV4;11 and THP-1 cells transduced with MEIS1-shRNA (left column). The right panels display ROS levels in Meis1f/f MLL-AF9 knockin or control leukemic cells treated with vehicle (V), 4-OHT, or a combination of 4-OHT and N-acetyl cysteine amide (NACA). (B) Bar graph depicting results of colony assay with Meis1f/f MLL-AF9 cells in the presence of vehicle or 4-OHT, with or without the addition of NACA to the media. Data are mean ± SEM *P < .01, Student t test. (C) Meis1f/f MLL-AF9 cells were transduced with retrovirus carrying SOD2, a nonfunctioning mutant of SOD2, or control retrovirus (MIT). The bar graph depicts colony numbers formed by transduced cells in each condition in the presence of vehicle or 4-OHT. (D) Mice were transplanted with Meis1f/f MLL-AF9 leukemic cells expressing firefly luciferase. Recipients were treated with vehicle, tamoxifen, or tamoxifen + NACA as described. Leukemia burden was analyzed by live-animal imaging. Representative images of mice in each group are shown. The bar graph on the right depicts measured bioluminescence in each group (n = 5 mice per group). (E-G) Oxygen consumption rates (OCR) were measured using the Seahorse XF analyzer. Representative graphs depict OCR measured at 5 minute intervals in control and Meis1f/f MLL-AF9 knockin, Meis1f/f with Meis1-overexpressed, and MV4;11 cells. After 3 measurements at baseline, the ATP-synthase inhibitor oligomycin was added to the wells (arrow) and measurements were repeated. All data points are mean ± SEM of triplicates. n = 3 independent experiments.