Figure 3

Anti-tumor efficacy of compound 8 in single or combined administration with the topoisomerase I inhibitor SN-38. (A) HT29 cells were exposed for 96 hrs to different doses (ranging from 0.1 to 0.8 μM) of the G4-ligand 1(▲) or 8(■). Surviving fractions were calculated as the ratio of absolute survival of the treated sample/absolute survival of the untreated sample. (B) HT29 cells were treated with 0.2 μM SN-38 for 2 hrs or with 0.2 μM 8 for 96 hours as single or in combined administration. In the histograms the surviving fractions calculated as in (A) are reported. Representative images of clonogenic ability of untreated or treated cells were showed below the histograms. (C) Combination Index for SN-38 and 8 was calculated by the Chou-Talalay method. Data plotted are CI at 50% (white squares), 75% (light gray squares), 90% (dark gray squares), and 95% (black squares) fraction killed. Data represent the means ± SD of 3 independent experiments.