Abstract: 　　　[ABSTRACT] Objective: To investigate the inhibitory effects of Periplocin from Cortex Periplocae (CPP) in human lung cancer cell line QG56 and to discuss its mechanism. Methods: Inhibitory effect of CPP in different concentrations (1.25, 2.50, 5.00, 10.00, 20.00 ng/ml) and different time (24 h, 48 h, 72 h) on QG56 proliferation was tested by MTT method. The morphological changes of the QG56 cells treated with CPP were observed by inverted microscope. The effects of CPP on cell cycle and cell apoptosis were determined by flow cytometry (FCM). Expression of apoptosis associated genes bax on cells was assessed by RT-PCR and SP immunocytochemistry method respectively before and after treatment of CPP. Results: Marked inhibitory effect of CPP on QG56 cells was observed. The morphological changes were displayed in QG56 exposed to CPP. The results of flow cytometry showed that the proportion of tumor cells in the G0/G1 phase was increased markedly, which of S and G2/M phase cells decreased, after treatment with CPP. The apoptosis rate of QG56 cells in CPP groups increased significantly compared to the control group (P0.05). The expression of bax mRNA was increased in QG56 exposed to CPP. The result of immunocytochemistry indicated that bax protein showed stronger positive staining in cells with CPP treatment. Conclusion: CPP has significant inhibitory effect on human lung cancer cell lines QG56, which is probably related to blocking cell cycle and induction of apoptosis.

Key words: Periplocin from Cortex Periplocae(CPP), human lung cancer, cell cycle, apoptosis