细胞周期检测点的流式细胞术分析

背景与目的:真核细胞的细胞周期运行遵循着严格的时相次序,这种精密的延缓和强制的次序,由细胞监控机制——检测点来完成,检测点功能的丧失会导致肿瘤的发生。传统的细胞周期检测点分析多数基于群体细胞DNA直方图的流式细胞术。本研究以晚G1期检测点为模式,建立一种新的细胞周期检测点分析方法——Cyclins/DNA双参数流式细胞术,并评价应用该方法进行细胞周期检测点分析的可行性和优越性。方法:将紫外线照射诱导后的人类急性淋巴细胞型白血病细胞株(MOLT-4)于不同时间点收获固定,分两组进行流式细胞仪检测:一组用DNA直方图法,Modifit软件分析计算G0/G1期细胞总数;另一组应用CyclinE/DNA双参数流式细胞术对G1晚期细胞CyclinE的荧光强度、阈值及G0/G1各亚期细胞数量进行定量分析,并比较两组实验结果。结果:用DNA直方图法观察到紫外线照射后0～4hG0/G1期细胞总数基本不变(5300～5500),6h后开始上升(6241,12.6%)。而用CyclinE/DNA双参数法观察到:(1)G1晚期细胞的CyclinE荧光强度于照射后短时间内便开始变化,1h上升为341.2(对照295.1,15.6%),6h上升为577.6(95.7%),此时CyclinE阈值上升到5.4(0h为2.0);(2)G0/G1各亚期细胞数目变化趋势不明显:G1晚期细胞数6h时略为减少(此时凋亡率为5.61%),G1早期细胞数缓慢上升。结论:CyclinE/DNA双参数流式细胞术将CyclinE的荧光强度及表达阈值定量化,对于细胞晚G1期检测点的检测比传统的DNA直方图法更为敏感和精确。

Analysis of cell cycle checkpoints by cyclins/DNA flow cytometry

BACKGROUND & OBJECTIVE: Eukaryotic cell cycle events progress strictly in order which is controlled by the mechanism of checkpoint. At present, most analyses of checkpoint use the flow cytometry (FCM) based on DNA histogram to detect cell cycle distribution. This study was designed to set up and evaluate a new method, Cyclins/DNA multiparameter FCM based on the model of late G1 phase (G1L) checkpoint, for analyzing cell cycle checkpoint. METHODS: After irradiation by ultraviolet (UV), human acute lymphatic leukemia MOLT-4 cells were gathered and fixed at different time points, and divided into 2 groups. In one group, the total G0/G1 phase cells were calculated by Modifit software using DNA histogram method; in the other group, fluorescence intensity and threshold of Cyclin E in G1L cells and G0/G1 phase cells were quantitatively analyzed by Cyclins/DNA multiparameter method. RESULTS: When analyzed by DNA histogram method, the percentage of G0/G1 phase cells was unchanged after irradiated for 0-4 h, but increased to 12.6% after irradiated for 6 h. When analyzed by Cyclins/DNA multiparameter method, the Cyclin E fluorescence intensity of G1L cells was increased from 295.1 (control) to 341.2 (15.6%) after irradiated for 1 h, and increased to 577.6 (95.7%) with the threshold increased from 2.0 (control) to 5.4 after irradiated for 6 h; G1L cells was slightly decreased after irradiated for 6 h when the apoptosis rate was 5.61%, and early G1 phase (G1E) cells was increased slowly. CONCLUSION: Cyclin E/DNA multiparameter FCM could quantitatively detect fluorescence intensity and threshold of Cyclin E, and is more sensitive and precise than DNA histogram FCM in detecting G1L checkpoint.