Panobinostat induces apoptosis in TNBC cells. (A) TNBC cells treated with panobinostat (100, 200 nM) or vehicle (DMSO) for 24 hours were assayed by DNA fragmentation (Cell Death ELISA) assay to assess changes in apoptosis. Data are presented as enrichment (mean ± SEM) versus control of two independent experiments (***, P < 0.001). (B) Representative confocal images show the presence of apoptotic bodies (arrows) in panobinostat treated MDA-MB-157, MDA-MB-231, and BT-549 cells at 18 hours. Cells stained red (rhodamine phalloidin) for actin filaments, green (Alexa Fluor® 488) for acetyl-histone H3 (Lys9), and blue for DAPI nuclear stain. Original magnification is 400× with scale bars at 20 microns. DAPI, 4',6-diamidino-2-phenylindole; DMSO, dimethyl sulfoxide; SEM, standard error of the mean; TNBC, triple-negative breast cancer.