To investigate the effect of KU0060648, TMZ or KU0060648/TMZ on apoptosis of glioma cells, U87 cells were treated with these agents alone or their combination for 48 hours and then cell apoptosis was assessed by flow cytometry (FCM). As shown in Figure 3A, 1 μM or 10 μM KU0060648 alone was able to increase the apoptotic rates to 14.8% and 56.9% respectively in U87 cells. 100 μM TMZ exerted minimal effect, while KU0060648 dose-dependently enhanced the apoptotic rate of TMZ treatment, which was certified in TUNEL assay (Figure 3B). To further classify the proapoptotic effect of combination treatment, morphological changes of U87 cells were evaluated using Hoechst staining (Figure 3C). 100 μM TMZ alone did not induce evident morphological alternations in U87 cells. 1 or 10 μM KU0060648 alone, or in combination with 100 μM TMZ could arouse the distinct morphology features of apoptosis, including the formation of apoptotic body and early coalescence of nuclear chromatin, margination and nuclear shrinkage. Similar results were obtained in M059K (Figure 3A - 3C). Notably, we discovered that treatment of KU0060648 increased the caspase 3/7 activity-promoting effect of TMZ in both U87 and M059K (Figure 3D), suggesting the synergistic augment of apoptosis caused by KU0060648 and TMZ majorly depended on the activation of caspases.