Liu Jiaxin, Zhang Yueting, Chen Li, Yu Fei, Li Xiaojin, Zhao Jianhua, Zhou Shuai
Department of Neurosurgery, The First Affiliated Hospital of Kunming University of Science and Technology, Kunming 650032, China.
VIP Ward, the Second Affiliated Hospital of Kunming Medical College, Kunming650032, China.
Acta Biochim Biophys Sin (Shanghai). 2017 Jun 1;49(6):479-486. doi: 10.1093/abbs/gmx033.
Glioblastoma is the most aggressive brain tumor, and its prognosis remains poor. Therefore, novel therapeutic strategies are needed for glioma therapy. Polyphyllin I (PPI), a bioactive constituent extracted from Paris polyphylla, was reported to have anti-tumor activity. However, the detailed mechanism for this activity remains unclear. Here, we investigated the inhibitory effects of PPI on glioma cells and its mechanisms in vitro. U251 cells were treated with various concentrations of PPI (2-9 μM) for 24 to 72 h. The inhibition of U251 cell proliferation by PPI was assessed by MTT assay. The effects on cell cycle and apoptosis were examined by flow cytometry with PI and annexin V-FITC/PI dual staining, and the cell mitochondrial membrane potential level was evaluated by fluorescence microscopy with JC-1 staining. The expression levels of apoptosis-related proteins and JNK signal pathway proteins were evaluated by western blot analysis. Results showed that PPI significantly inhibited the proliferation of U251 cells in a concentration-dependent manner. PPI induced G2/M phase arrest and apoptosis, and it upregulated the expressions of Bax, cytochrome c, and p-JNK, but downregulated the expression of the anti-apoptotic protein Bcl-2 in U251 cells. Moreover, PPI provoked the depolarization of the mitochondrial membrane potential. In addition, apoptosis induced by the PPI was remarkably suppressed by the JNK inhibitor SP600125. Our data provide evidence that PPI inhibits proliferation and induces apoptotic cell death in U251 cells. This effect may be associated with the JNK pathway. These results suggest that PPI is an activator of the JNK signaling pathway with a potential anti-glioma effect.
胶质母细胞瘤是最具侵袭性的脑肿瘤，其预后仍然很差。因此，胶质瘤治疗需要新的治疗策略。重楼皂苷I（PPI）是从七叶一枝花中提取的一种生物活性成分，据报道具有抗肿瘤活性。然而，这种活性的详细机制仍不清楚。在这里，我们研究了PPI对胶质瘤细胞的抑制作用及其体外机制。用不同浓度的PPI（2-9μM）处理U251细胞24至72小时。通过MTT法评估PPI对U251细胞增殖的抑制作用。通过PI和膜联蛋白V-FITC/PI双重染色的流式细胞术检测对细胞周期和凋亡的影响，并用JC-1染色通过荧光显微镜评估细胞线粒体膜电位水平。通过蛋白质印迹分析评估凋亡相关蛋白和JNK信号通路蛋白的表达水平。结果表明，PPI以浓度依赖性方式显著抑制U251细胞的增殖。PPI诱导G2/M期阻滞和凋亡，并上调U251细胞中Bax、细胞色素c和p-JNK的表达，但下调抗凋亡蛋白Bcl-2的表达。此外，PPI引起线粒体膜电位的去极化。此外，JNK抑制剂SP600125显著抑制了PPI诱导的凋亡。我们的数据提供了证据表明PPI抑制U251细胞的增殖并诱导凋亡性细胞死亡。这种作用可能与JNK途径有关。这些结果表明，PPI是一种具有潜在抗胶质瘤作用的JNK信号通路激活剂。
