CFZ interacts synergistically with CPT-11 on CRC cells. (A) Inhibitory effect of CFZ on human colorectal cancer cell proliferation. SW620 cells were treated with 10, 20, 50, 100 and 200 nM of CFZ and 8, 20, 50, 100 and 200 μM of CPT-11 for 24, 48 and 72 h. HCT8 cells were treated with 150, 300, 600, 1,200 and 2,400 nM of CFZ and 50, 80, 100, 200 and 300 μM of CPT-11 for 24, 48 and 72 h. The WST-1 assay determined cell proliferation. (B) Using the same concentration of CFZ (50, 100 and 600 nM) on SW620 cells and HCT8 cells, we find that SW620 cells were more sensitive to CFZ than HCT8. NF-κB was detected by EMSA. (C) CFZ and CPT-11 exhibit synergistic cytotoxicity on SW620 cells. SW620 cells were treated with CFZ and CPT-11 at the indicated concentrations for 48 h. Each CFZ concentration was combined with 50, 100 and 200 μM of CPT-11 as showed in Table 1. Cell viability was measured using the WST-1 assay. Effects of CFZ and CPT-11 on the colony formation of SW620 cells. The colonies (>50 cells) were scored after 14 days. (d-1) SW620 cells were treated with 0.5, 1, 1.5, 2 and 2.5 nM of CFZ, colony number decreased as the concentration of CFZ increased. (d-2) SW620 cells were treated with 0.5 or 1 nM of CFZ and with 2 μM CPT-11. The number of colonies significantly decreased compared to CFZ or CPT-11 treatment alone. All the above data shown represent the mean ± SEM (n=3).