Synergistic Effects of Simvastatin and Irinotecan against Colon Cancer Cells with or without Irinotecan Resistance

Figure 5

Synergistic effect of simvastatin and irinotecan on cell death in HT-29 cell and irinotecan-resistant HT-29 cells. Cell apoptosis was assessed by the detection of monooligonucleosomes (histone-associated DNA fragments) using an ELISA technique in HT-29 cells and HT-29R cells. (a) HT-29 cells were treated for 48 h with simvastatin (SV) alone, irinotecan (IR) alone, and combination of SV and IR at 2 : 1 molar ratio in which the concentration of SV and IR was 57.7 μM and 15.625 μM, respectively. (b) HT-29R cells were treated for 48 h with SV alone, IR alone, and combination of SV and IR at 2 : 1 molar ratio in which the concentration of SV and IR was 111 μM and 49 μM, respectively. Increased apoptotic responses were evident in combination treatment group of the cells relative to untreated control and single treatment of SV or IR in HT-29 cells and HT-29R cells. The data are expressed as the means ± SD from three independent experiments. , compared to untreated control cells. , compared to untreated control cells; , compared to SV alone; , compared to IR alone.

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