Weng Xi-Yang, Ma Run-Di, Yu Li-Jian
Guangdong Provincial Key Laboratory of Marine Materia Medica, Zhanjiang Ocean University, Zhanjiang, Guangdong, 524025, PR China.
Ai Zheng. 2003 Aug;22(8):806-11.
BACKGROUND & OBJECTIVE: Tubeimu, Bolbostemma pani- culatum(Maxim.) Franquet (Cucurbitaceae), is a kind of traditional Chinese medicinal herb. Our previous studies revealed that tubeimoside I, a triterpenoid saponin isolated from the tubers of Bolbostemma paniculatum, showed potent antitumor effect. This study was designed to investigate the effect of tubeimoside I on the apoptosis of human nasopharyngeal carcinoma cell line CNE-2Z.
Cell growth inhibition mediated by tubeimoside I was measured by MTT assay after treatment with tubeimoside I. The effect of tubeimoside I on apoptotic induction in CNE-2Z cells was determined using the fluorescent microscopy, electronic microscopy,DNA agarose gel electrophoresis, and flow cytometry,respectively. Western blot analysis was performed to detect the changes of apoptosis-related genes bcl-2 and bax protein expression.
Tubeimoside I displayed growth inhibitory activity against CNE-2Z cells with IC(50) values of 32.5, 20.7, and 16.7 micromol/L for 24, 48, and 72 hours, and CNE-2Z cells showed typical apoptotic morphological features observed by fluorescent microscopy and electronic microscopy. In CNE-2Z cells occurred typical "Ladder"bands after being exposed to tubeimoside I (10 micromol/L, 24, 48, 72 hours; 30, 40, 50, 60 micromol/L, 12 hours). Sub-G1 peak was found using flow cytometry. When CNE-2Z cells were exposed to tubeimoside I (50 micromol/L, 12 hours), the apoptosis index was 72.8%. The down regulation and phosphorylation of bcl-2 (an inhibitor of apoptosis) were detected at 1 hour after the addition of tubeimoside I. In contrast, the levels of bax appeared to be significantly upregulated at 1, 3, 5, and 24 hours after the addition of tubeimoside I.
Tubeimoside I can induce the apoptosis of CNE-2Z cells, and the induction of apoptosis by tubeimoside I is closely associated with downregulation and phosphorylation of bcl-2 and bax activation.
土贝母为葫芦科植物土贝母Bolbostemma paniculatum(Maxim.) Franquet的干燥块茎，是一味传统的中药材。前期研究发现，从土贝母块茎中分离得到的三萜皂苷土贝母苷甲具有较强的抗肿瘤活性。本研究旨在探讨土贝母苷甲对人鼻咽癌CNE-2Z细胞凋亡的影响。
采用MTT法检测土贝母苷甲对CNE-2Z细胞生长的抑制作用；运用荧光显微镜、电子显微镜、DNA琼脂糖凝胶电泳及流式细胞术分别检测土贝母苷甲对CNE-2Z细胞凋亡的诱导作用；采用蛋白质免疫印迹法检测凋亡相关基因bcl-2和bax蛋白表达的变化。
土贝母苷甲对CNE-2Z细胞生长具有抑制作用，作用24、48及72小时的IC(50)值分别为32.5、20.7和16.7 μmol/L，荧光显微镜及电子显微镜观察可见CNE-2Z细胞呈现典型的凋亡形态学特征；经土贝母苷甲（10 μmol/L，作用24、48、72小时；30、40、50、60 μmol/L，作用12小时）作用后，CNE-2Z细胞出现典型的“梯状”条带；流式细胞术检测出现亚G1峰；土贝母苷甲（50 μmol/L，作用12小时）作用后，CNE-2Z细胞凋亡指数为72.8%；加入土贝母苷甲1小时后，凋亡抑制基因bcl-2表达下调且发生磷酸化；而加入土贝母苷甲1、3、5及24小时后，促凋亡基因bax表达明显上调。
土贝母苷甲可诱导CNE-2Z细胞凋亡，其诱导凋亡作用与bcl-2表达下调及磷酸化、bax激活密切相关。
