Abstract: Objective: To explore the apoptosis of human gastric cancer MGC-803 cells induced by toosendanin(TSN) and its mechanism. Methods: The human gastric cancer MGC-803 cells were divided into 5 groups, each group was set with 3 replicate. Fluorouracil (5-FU) and 0 nmol/L toosendanin (TSN) were used as positive control and negative control, respectively. The other three groups were treated with toosendanin at the final concentrations of 30, 50, and 70 nmol/L, respectively. After 48 h of treatment with toosendanin, the morphology of the cells were observed under laser confocal microscopy. Flow cytometry was used to detect the mitochondrial membrane potential, and enzyme-labeled assays were used to detect the activities of Caspase-3 and Caspase-9. The mRNA and protein levels of Bcl-2, Bax, Cyt c and APAF-1 were measured by qRT-PCR and Western blot. Results: Compared with the 0 nmol/L TSN group, after the human gastric cancer MGC-803 cells were treated with toosendanin at the concentrations of 30, 50, and 70 nmol/L for 48 h, the cell volume shrinkage, nucleus cleavage and chromatin morphological changes were observed under the microscope. The activities of Caspase-3 and Caspase-9 were increased significantly (P＜0.05), while the mitochondrial membrane potential was decreased significantly (P＜0.05). In addition, the mRNA and protein expression levels of Bax, Cyt c and APAF-1 were increased significantly (P＜0.05), while the mRNA and protein expression levels of Bcl-2 were decreased significantly (P＜0.05). Conclusion: Toosendanin up-regulates the expressions of Bax, Cyt c and APAF-1, down-regulates the expression of Bcl-2 gene, enhances the activities of caspase-3 and caspase-9, and induces the apoptosis of human gastric cancer MGC-803 cells.

Key words: toosendanin, MGC-803cells, cell apoptosis