Fig. 5

Effect of the combination of Actinomycin D with SAHA in vitro. a and b Cells were treated for 48 h with the indicated concentrations of SAHA in presence or absence of actinomycin D at 0.25 nM (SK-N-JD) or 2.5 nM (LA1-55n) and cell viability was measured. c and d Isobolograms representing actinomycin D and SAHA interaction analyzed by the Chou-Talalay median effect method. The additivity line is the one uniting each drug concentration needed to inhibit cell growth by 50 % (IC50), 75 % (IC75) or 90 % (IC90). The colored shapes under this line denote synergism. e Graphic representation of IC values at IC50, IC75 and IC90. f Cells were treated (+) or not (−) with actinomycin D in the presence (+) or absence (−) of SAHA for 48 h. Concentrations used were 0.3 nM actinomycin D and 0.7 μM SAHA in SK-N-JD cells, and 1 nM actinomycin D and 1 μM SAHA in LA1-55n cells. Protein expression was determined by Western blot analysis. g LA1-55n cells were treated (+) or not (−) with 0.1 nM of actinomycin D in the presence (+) or in the absence (−) of 1 μM SAHA. The indicated proteins expression was determined after 24 h after treatment by Western blot analysis