Vorinostat decresases Bcl-xL protein levelsand enhances the effect of doxorubicin and gemcitabine chemotherapy in HL. (A) Vorinostat (5 μM) decreases the level of the antiapoptotic protein Bcl-xL in HL cell lines in a time dependent manner as determined by Western blot. (B) Representative experiments demonstrating synergistic effects between vorinostat and doxorubicin (left panel) and gemcitabine (right panel). Cells were incubated with each drug alone or in combination for 48 hours and cell viability was determined by the MTS assay. Synergy was determined by calculating the combination index (CI) analyzed by Calcusyn software. Each value represents a mean of 3 independent experiments performed in triplicate (± SEM). (C) Synergy between Vorinostat and gemcitabine (top table) or doxorubicin (bottom table) using a range of drug concentrations. Synergy was determined by calculating the CI using the Calcusyn software. A CI less than 1 indicates synergy.