Promotion of combination of chrysin and camptothecin on apoptosis of CNE2 cells / 中草药

ABSTRACT

objective To research whether the combination of chrysin and camptothecin can promote the apoptosis of human nasopharyngeal carcinoma cell line CNE2 and to explore the molecular mechanism of the combinative effect. Methods: CNE2 cells were pretreated with designed dose of chrysin (10|, 20, and 40 μmol/L) for 2 h, then treated with camptothecin (1 μg/mL) for 24 h. The morphologic changes were observed under inversed microscope and the cell viability was measured using MTT. The activity of caspase-3 and PARP, which was regarded as the protein marks of apoptosis, was determined by Western blotting. Then the cells were treated with chrysin for different time and the time course of apoptosis inhibitory protein, Bcl-xL was also detected using Western blotting. Results: Increases of cell death were observed in the group with combined chrysin and camptothecin, but no obvious cell death could be found in chrysin, camptothecin alone, and control groups; The data of cell viability supported this results; With the enhance of pretreatment dose of chrysin, the cell viability decreased. There were the significant differences between the combined groups and the control one (P<0.05), and between the combined groups and both the chrysin and camptothecin groups separately (P<0.05). Chromatin condensation, which was the indication of apoptosis, could be observed when the cells were stained with Hochest 33342; The proprotein of caspase-3 and PARP degraded and there were the dose-dependent and time-dependent effect. The pan-caspase inhibitor Z-VAD-fmk could inhibit the apoptosis of CNE2 cells which were treated with the combination of chrysin and camptothecin, according to the cell viability and the activation of caspase-3 and PARP; The time-dependent down-regulation in the apoptosis inhibitory protein Bcl-xL could be observed. Conclusion: The cotreatment of chrysin and camptothecin could promote the apoptosis of CNE2 and the down-regulation of apoptosis inhibitory protein Bcl-xL played an important role in the combinative effect.