Fig 6. Buparlisib synergizes with NVP-AEW541 to further reduce Akt phosphorylation and augment apoptosis.

(A) Cells were exposed to a series of 1.5-fold dilutions of buparlisib and NVP-AEW541 alone or in combination at a constant ratio of 1:3 (TC-32, A4573, RD) or 1:1 (SJCRH30) for 72 hours, then cell viability was determined by MTT assay. Columns represent the average of three independent experiments, error bars represent standard deviation. Combination index values greater than 1, equal to 1, or less than one indicate antagonism, additivity, or synergy. (B) Isobologram plot of the effect of buparlisib combined with NVP-AEW541. The effective doses of NVP-AEW541 and buparlisib are plotted on the x- and y-axis with lines of linear additivity connecting the ED₅₀, ED₇₅, and E₉₀ for individual treatments. Points for combination treatment above, on, or below the lines indicate antagonism, additivity, or synergy, respectively. (C) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-Erk1/2 (T202/204 on Erk1, T185/187 on Erk2), and total Erk1/2 in A4573 cells after 1 hour of treatment with buparlisib, NVP-AEW541, or both. (D) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-Erk1/2 (T202/204 on Erk1, T185/187 on Erk2), total Erk1/2, cleaved PARP, and actin in A4573 cells after 24 hours of treatment with buparlisib, NVP-AEW541, or both.