Panobinostat (LBH589)–induced death by apoptosis and autophagy in HL cell lines. (A) Three HL cell lines (HDLM-2, L-428, and KM-H2) were incubated with increasing doses of LBH589 (0.01-1μM). After 24, 48, and 72 hours, cell viability was determined by an MTS assay. Each value represents the mean ± SEM of the results of 3 independent experiments performed in triplicate. (B) IC₅₀ for LBH589 is reduced in all HL cell lines after 72 hours. Data represent the mean of 3 independent experiments performed in triplicate. (C) HL cell lines were treated or not with 0.05μM of LBH589 for 48 hours. Apoptosis was determined by annexin V–FITC/propidium iodide double staining. Percentages of cells showing apoptosis (combined right quadrants) are shown in the boxes. (D) Summary of the results of annexin V–FITC/propidium iodide double staining from 3 independent experiments. Each value represents the mean of 3 independent experiments performed in triplicate. **P < .005. ns indicates not significant. (E) HL cell lines were incubated for 48 hours with diluent control or LBH589 (0.02-0.1μM), and intracellular protein levels were examined by Western blot. LBH589 induced cleavages of caspase 9 and PARP and decreased XIAP and Bcl2 levels in all cell lines.