FIGURE 3.

CHR‐6494 potentiates the killing efficacy of MLN8237 on breast cancer cells. A. Colony formation assay shows the effects of CHR‐6494 on MLN8237 sensitivity in MDA‐MB‐231 and SKBR3 cells. B and C. Relative apoptosis of MDA‐MB‐231 and SKBR3 cells treated with indicated drugs for 72 hours. The concentrations of MLN8237 were 200 nmol/L in MDA‐MB‐231 cells and 70 nmol/L in SKBR3 cells. The concentrations of CHR‐6494 were 200 nmol/L in both cells. One‐way ANOVA and LSD tests were used to evaluate the difference between groups. ns, not significant; n = 3 independent experiments; **P < 0. 01, ***P < 0.001. D and E. MDA‐MB‐231 and SKBR3 cells were treated with the indicated doses of MLN8237 and CHR‐6494 for 96 hours, followed by MTT assay to determine the growth‐inhibitory effects. n = 3 independent experiments. The combination index was analyzed with the CompuSyn software. Abbreviations: PI, Propidium iodide