Fas诱导MML-1凋亡时活化caspase-3表达与细胞周期的关系

目的研究Fas诱导的B淋巴细胞瘤细胞株MML-1凋亡过程中，细胞内活化caspase-3表达与细胞周期的关系。方法抗Fas抗体孵育MML-1不同时间以诱导细胞凋亡，流式细胞仪检测凋亡率并验证MML-1对Fas诱导凋亡的敏感性。采用PI—Triton X和FITC—active caspase-3双染色分析经Fas诱导凋亡的MML—1内活化caspase-3的表达。以细胞周期蛋白cyclin A、B1、E标记Fas诱导凋亡的处于不同增殖周期MML-1（S、G2／M和G1期细胞），流式细胞术检测细胞内活化caspase-3的表达。结果Fas诱导6h后，MML-1凋亡率达到56％。Fas诱导4h后，活化caspase-3在G1期细胞内表达显著升高，仅有少量S期和G，／M期细胞表达活化caspase-3。Cyclin A、B1阴性而cyclinE阳性MML-1表达活化caspase-3。结论Fas诱导MML-1凋亡过程中，细胞内活化caspase-3的表达与细胞周期有关。G1后期和S早期的MML-1最先表达活化caspase-3，且对Fas诱导凋亡的敏感性最高。

Relationship between expression of active form of caspase-3 and cell cycle in Fas-mediated apoptosis of MML-1 cells

Objective To investigate the relationship between expression of active form of caspase-3 and cell cycle in Fas-mediated apoptosis of B lymphocytoma cell line MML-1. Methods MML-1 cells were incubated with agonistic anti-Fas antibody for different time,and cell apoptosis was induced.Cell apoptotic rates were analysed by flow cytometry,and sensitivity of MML-1 cells to apoptosis was determined.The expression of active form of caspase-3 was analysed by double staining with PI-Triton X and FITC-active caspase-3.Cyclin A,B_1 and E were selected as cell cycle markers for S,G_2/M and G_1 phase of MML-1 cells,and the expression of active form of caspase-3 was detected by flow cytometry. Results The cell apoptotic rate reached 56% after induction by Fas for 6 h.After induction by Fas for 4 h,the active form of caspase-3 was mainly expressed in cells of G_1 phase,while rarely in cells of S and G_2/M phase.Cells with negative cyclin A and B_1 and positive cyclin E expressed active form of caspase-3. Conclusion The expression of active form of caspase-3 in MML-1 cells mediated by Fas might be cell cycle dependent.Cells entering into late G_1 and early S phase first express active form of caspase-3,and their sensitivity to Fas-mediated apoptosis is the highest.