Cheng Guang, Zhang Xiang, Tang Hai-Feng, Zhang Yun, Zhang Xin-Hai, Cao Wei-Dong, Gao Da-Kuan, Wang Xi-Ling, Jin Bo-quan
Department of Neurosurgery of Xijing Hospital (Neurosurgery institute of Chinese PLA), The Fourth Military Medical University, 710032, Xi'an, ShannXi, China.
J Neurooncol. 2006 Sep;79(3):235-41. doi: 10.1007/s11060-006-9136-y. Epub 2006 Apr 21.
Malignant glioblastoma is one of the most common malignant tumors in the neurological system. Asterosaponin 1, a new cytostatic agent from the starfish Culcita novaeguineae appear to exhibit various biological activities, including antitumor effect, but the function and mechanism of this new agent on glioblastoma cells has not previously been determined. In the present study, we investigated the proliferation change of human glioblastoma U87MG cells exposed to different concentrations (2.5-20.0 microg/ml) of asterosaponin 1 for a certain time. The results showed that asterosaponin 1 significantly suppressed U87MG cell proliferation in a time- and dose-dependent manner (IC50 =4.3 microg/ml). Flow cytometric analysis of DNA in U87MG cells showed that asterosaponin 1 induces the prominent appearance of a sub-G1 peak in the cell cycle suggestive of apoptosis identical with the result of annexin V/PI assay. Furthermore, U87MG cells treatment with asterosaponin 1 resulted in nuclear condensation with apoptotic bodies observed by both fluorescence and electron microscopy. Agarose gel electrophoresis of DNA from asterosaponin 1-treated cells revealed a typical "ladder" consistent with apoptotic DNA fragmentation. Western-blot staining showed asterosaponin 1 decreased the expression of Bcl-2 protein and increased the expression of Bax protein. The novel findings suggest that the cytostatic actions of asterosaponin 1 toward U87MG cells result from the induction of cell apoptosis. Overall, our data demonstrate that asterosaponin 1 is fully equipped for an efficient apoptotic killing of glioblastoma cells and suggest that this mechanism may play a critical role in anti-tumor chemotherapy.
恶性胶质母细胞瘤是神经系统中最常见的恶性肿瘤之一。海星新几内亚 Culcita novaeguineae 中的一种新型细胞生长抑制剂海星皂苷 1 似乎具有多种生物学活性，包括抗肿瘤作用，但此前尚未确定这种新药物对胶质母细胞瘤细胞的功能和作用机制。在本研究中，我们研究了人胶质母细胞瘤 U87MG 细胞在一定时间内暴露于不同浓度（2.5 - 20.0 μg/ml）海星皂苷 1 后的增殖变化。结果表明，海星皂苷 1 以时间和剂量依赖性方式显著抑制 U87MG 细胞增殖（IC50 = 4.3 μg/ml）。对 U87MG 细胞 DNA 的流式细胞术分析表明，海星皂苷 1 在细胞周期中诱导出现明显的亚 G1 峰，提示细胞凋亡，这与膜联蛋白 V/PI 检测结果一致。此外，用海星皂苷 1 处理 U87MG 细胞导致细胞核浓缩，并通过荧光显微镜和电子显微镜观察到凋亡小体。对海星皂苷 1 处理细胞的 DNA 进行琼脂糖凝胶电泳，显示出与凋亡 DNA 片段化一致的典型“梯形”条带。蛋白质免疫印迹染色显示，海星皂苷 1 降低了 Bcl-2 蛋白的表达，增加了 Bax 蛋白的表达。这些新发现表明，海星皂苷 1 对 U87MG 细胞的细胞生长抑制作用是由诱导细胞凋亡引起的。总体而言，我们的数据表明，海星皂苷 1 具备有效诱导胶质母细胞瘤细胞凋亡的能力，并表明这种机制可能在抗肿瘤化疗中起关键作用。
