中文摘要：

目的：研究土贝母苷甲（ TBMS Ⅰ）诱导人胶质瘤U251细胞凋亡及其可能的内在机制。方法四甲基偶氮唑蓝比色法（ MTT法）检测不同浓度的土贝母苷甲对U251细胞增殖的影响。 Hoechst 33258荧光染色观察不同浓度土贝母苷甲处理 U251细胞后细胞核形态的变化。流式细胞仪检测细胞的凋亡率。Western blot 分析土贝母苷甲对FADD、caspase-8和caspase-3蛋白表达水平的影响。结果土贝母苷甲以剂量依赖方式抑制U251细胞的增殖。土贝母苷甲处理后，U251细胞的细胞核表现出固缩浓染等凋亡特征，且随着药物浓度的增加，细胞数目逐渐减少。与对照组相比较，土贝母处理组（10、20、25μg／ml）的早期和晚期凋亡率均显著增加，差异有统计学意义（P﹤0．05）。10、20、25μg／ml 土贝母苷甲处理组上调了FADD、caspase-8和caspase-3蛋白的表达水平，差异有统计学意义（P﹤0．05）。结论土贝母苷甲在体外能够明显的抑制U251细胞的增殖，其机制可能与上调FADD、caspase-8和caspase-3蛋白表达从而诱导细胞凋亡有关。

英文摘要：

Objective To investigate the molecular basis for apoptosis of glioma by tubeimoside-1 （ TBMS Ⅰ） in U251 cell line.Methods U251 cells were exposed to different concentrations of tubeimoside-1, cell proliferative activity was evaluated using MTT assay.The changes of nuclei morphology of U251 cells after tubeimoside-1 treatment were observed using Hoechst 33258 staining.Apoptotic rate induced by tubeimoside-1 treatment was measured by flow cytometry using Annexin V-FITC/PI staining. The expression levels of FADD, caspase-8 and caspase-3 were detected by western blot analysis.Results Tubeimoside-1 suppressed proliferation of U251cells was dependent on dose.With the addition of tubeimoside-1, the nuclei of U251cells were shrunken with bright blue nuclear staining which indicted apoptosis and the cell number was obviously decreased.The ratio of early and late apoptotic cells was significantly increased by tubeimoside-1 treatment （10,20,25 μg/ml） compared with the control group （P 〈0.05）. Furthermore, 10,20 and 25 μg/ml tubeimoside-1 treatment led to an increase of FADD expression （P〈0.05）, the similar trend was seen in caspase-8（P〈0.05）and caspase-3 as well（P〈0.05）. Conclusions Tubeimoside-1 inhibited the proliferation of U251 cell line in vitro.The growth inhibitory mechanism may be associated with upregulation of FADD, caspase-8 and caspase-3 expression resulting in apoptosis.