DNA拓扑异构酶Ⅰ抑制剂诱导鼻咽癌上皮细胞凋亡的实验研究

Apoptosis of nasopharyngeal carcinoma cells induced by topoisomerase Ⅰ Inhibitor

拟从细胞凋亡角度出发，探讨能够诱导鼻咽癌上皮细胞凋亡的因素，为有效地防治该恶性肿瘤提供新的思路。方法：光镜下观察细胞的形态变化；流式细胞仪检测细胞周期变化及亚二倍体比例；ＤＮＡ凝胶电泳及二苯胺法测定ＤＮＡ片段化程度。结果：一定浓度的拓朴异构酶Ⅰ（Ｔｏｐｏｉｓｏ－ｍｅｒａｓｅⅠ，ＴＯＰＯⅠ）抑制剂喜树碱（Ｃａｍｐｔｏｔｈｅｃｉｎ，ＣＰＴ）体外作用于人低分化鼻咽癌上皮细胞系ＣＮＥ－２Ｚ细胞一定时间后，镜下可见细胞体积缩小，染色质凝聚，胞膜突起及凋亡小体形成等形态变化。２～１０μｍｏｌ／Ｌ的ＣＰＴ分别作用１２小时后作流式细胞仪检测，亚二倍体比例均为３０％左右；各浓度分别作用２４小时，亚二倍体比例均为５０％左右；同时细胞周期有明显的变化，主要表现为Ｇ２／Ｍ期细胞减少。ＤＮＡ琼脂糖凝胶电泳呈典型的梯形带。结论：拓朴异构酶Ⅰ抑制剂ＣＰＴ对人低分化鼻咽癌上皮细胞具有明显的凋亡诱导作用。

Purpose: to determine if the topoisomeraseⅠinhibitor Camptothecin(CPT) can induce apoptosis in vitro in a human nasopharyngeal carcinoma(NPC) cell line with low differentiation (CNE2Z). Methods: the light microscopy, flow cytometry and agarose gel electrophoresis were used to examine the morphological changes,cell cycle distribution , hypodiploid cells and DNA fragmentation. Results: After exposure to CPT for a certain period, CNE2Z cells underwent obvious morphological changes with characteristics of apoptosis such as decrease in cell volumes condensation of chromatin and the formation of apoptotic bodies. Flow cytometry(FCM) test showed that when CNE2Z cells were treated with 2 ～10μmol/L CPT for 12 or 24 hours,hypodiploid cells accounted for 30% and 50% respectively.Cell cycle analysis by FCM revealed that changes in CNE2Z cell cycle distribution were apparent 24 hours after treatment with various doses of CPT, showing no obvious dosedependent relationship.Compared with controls,the percentage of cells in G2/M phase decreased markedly while those in G1 and S phases increased moderately. Conclusion: the results demonstrated that DNA topoisomerase Ⅰ inhibitor Camptothecin Can induce apoptosis in CNE2Z cells in vitro.