Figure 2.

NF-κB pathway inhibitors potentiated topotecan-induced growth inhibition and caspase-3 activation in neuroblastoma cells. (A) Synergistic growth inhibition effect of topotecan and NSC 676914 in combination in three neuroblastoma cell lines (combination index <1). Sub-IC50 drug doses are used in combination and cell growth is plotted in the normalized isobolograms. (B) Normalized isobolograms showed synergy in growth inhibition by the combination of topotecan and bortezomib in three neuroblastoma cell lines. Shown is representative of three independent experiments. (C) Synergistic inhibitory effect of topotecan (1 μM) and bortezomib (2.5 nM) on cell proliferation in SK-N-AS cells using a real-time cell electronic sensing system (*P = 0.00005). (D) Increased percentage of apoptotic SK-N-AS cells measured by caspase-3 activation with the drug combinations comparing to single drug. (E) Immunoblots showed inactivation of the NF-κB pathway by treating cells with bortezomib through inhibition of degradation of total IκB-α protein