EM-3通过Stat3通路诱导鼻咽癌细胞凋亡和G_2/M期阻滞并降低SP细胞比例

EM-3 Targets Stat3 to Induce Apoptosis,G_2/M Cell Cycle Arrest and Reduce the Proportion of SP Cells in Nasopharyngeal Carcinoma

目的:研究白花地胆草(Elephantopus mollis H.B.K)的乙醇提取物EM-3抗肿瘤作用分子机制。方法:MTT、克隆形成抑制和细胞划痕实验检测EM-3对鼻咽癌细胞增殖、迁移能力的影响;Annexin V-FITC/PI双染法检测细胞凋亡;PI单染检测细胞周期;超速流式分选细胞仪检测鼻咽癌CNE2-S18肿瘤干细胞样SP细胞(side population cell)比例;Western blotting检测细胞凋亡、周期、侵袭迁移及肿瘤干细胞相关蛋白表达变化。结果:MTT、克隆形成抑制和细胞划痕实验结果表明,EM-3可以显著抑制鼻咽癌细胞的增殖,随着药物浓度的增大,细胞克隆数逐渐减少,体积逐渐变小,而且能够显著抑制鼻咽癌细胞的迁移;流式细胞术结果表明随着药物浓度的增加,凋亡率逐渐增加,并且G_2/M期细胞比例逐渐增加;超速流式分选细胞仪结果表明,EM-3可以显著降低CNE2-S18肿瘤干细胞样SP细胞的比例;Western blotting结果表明,随着药物浓度的增加,x IAP、Bcl-2、Cyclin D1、MMP2(药物高浓度)、MMP9、p-Met、Oct4(药物高浓度)及Sox2蛋白表达减少,而Cyclin B1、Bax蛋白表达增多,并伴随Caspase-9、Caspase-3活化及多聚ADP核糖聚合酶PARP酶切失活。结论:EM-3通过抑制Stat3通路诱导鼻咽癌细胞发生凋亡,并诱导G_2/M期阻滞。此外,EM-3经MMPs途径抑制鼻咽癌细胞迁移,同时可以有效降低CNE2-S18肿瘤干细胞样SP细胞干性。

Objective： To investigate the antitumor mechanism of EM-3, a ethanol extracts from Elephantopus mollis H. B. K,in nasopharyngeal carcinoma. Methods： The effects of EM-3 on the cell proliferative and migratory activity of CNE2,CNE2-S18 and L02 cells were detected by MTT assay,colony formation assay and cell scratch assay. Cell apoptosis was evaluated by Annexin V-FITC / PI double staining. Cell cycle was evaluated by PI single staining. The percentage of SP cells from CNE2-S18 cells was analyzed by fluorescenceactivated cell sorting（ FACS） assay. Expressions of apoptosis-relative proteins,cycle-relative,migration-relative proteins and cancer stem cells related proteins in CNE2 cells were measured by Western blotting. Result： The proliferation and migration of nasopharyngeal carcinoma was inhibited by EM-3 in a dose and time-dependent manner. Colony formation assays showed that EM-3 decreased colony formation compared with control. Flow cytometry analysis showed an increase of the percentage of apoptotic cells and G_2/M phase in a dose-dependent manner treated with EM-3. FACS assays demonstrated that EM-3 decreased the percentage of CNE2-S18 stemlike SP cells. EM-3 downregulated the expression of x IAP,Bcl-2,Cyclin D1,MMP2（ high drug concentration）,MMP9,p-Met,Oct4（ high drug concentration） and Sox2 with different concentrations. In addition,active bands of Caspase-9,Caspase-3 and PARP could be detected using Western blotting. But the expression of Cyclin B1 and Bax was upregulated. Conclusions： EM-3 induces the apoptosis and G_2/M cycle arrest by down-regulation of Stat3 signaling pathway. In addition,EM-3 inhibits cell migration by MMPS pathway and can effectively reduce the maintenance of CNE2-S18 stem-like SP cells.