Palbociclib selectively and potently induces apoptosis in FLT3-ITD leukemic cells. (A-B) Cells were incubated with palbociclib (1 µM) for 72 hours, stained with propidium iodide, and analyzed by flow cytometry. Treatment induces apoptotic sub-G1 fraction in FLT3-mutant cells (MOLM-14, PL-21, and MV4-11) but not in control cells (THP-1 and NOMO-1). (A) Representative dot blots and (B, lower panel) 1 representative histogram are depicted. (B, upper panel) Bar graphs show distribution of indicated cells in sub-G1 fraction. (C) Palbociclib (1 µM)-induced apoptosis was evaluated on day 4 by labeling indicated cells with annexin V/7-aminoactinomycin D (7-AAD) via fluorescence-activated cell sorting analysis. The percentage of cells in the upper left quadrant denotes cells that stained positive for annexin V only (early apoptosis). The cells in the upper right quadrant stained positive for annexin V and 7-AAD (late apoptosis). The percentage of cells in the lower right quadrant represents cells that stained positive for 7-AAD only (necrosis). Three independent experiments were carried out. Error bars indicate ± SEM. **P < .001. n.s., not significant. PI-A, propidium iodide area; PI-W, propidium iodide width.
