甲异靛诱导白血病细胞HL-60凋亡及机制探讨

背景与目的:甲异靛可有效治疗慢性粒细胞白血病,但其抗白血病的机制尚不清楚。本研究拟观察甲异靛诱导急性白血病细胞株HL-60细胞凋亡的作用及促凋亡机制。方法:用台盼蓝拒染实验观察甲异靛对HL-60细胞增殖抑制作用;琼脂糖凝胶电泳检测DNA条带;荧光显微镜观察细胞形态学的变化;流式细胞术检测细胞凋亡率和Fas蛋白的表达;免疫蛋白印迹法分析caspase-9、caspase-8、caspase-3、PARP、bcl-2、bax和胞浆细胞色素c的含量。结果:甲异靛可抑制HL-60细胞增殖和诱导其凋亡。20μmol/L甲异靛处理HL-60细胞12～48h可明显抑制HL-60细胞增殖;20μmol/L甲异靛作用于HL-60细胞1h,凋亡百分比为(3.70±0.56)%,当延长至3h、6h和12h凋亡细胞比例分别上升至(19.80±1.13)%、(29.20±2.69)%和(47.05±7.70)%,较阴性对照组[(2.65±0.78)%]明显增高(P<0.05)。HL-60细胞经甲异靛处理3h后出现细胞核染色质浓集和DNA梯形条带。甲异靛处理HL-60细胞1h后死亡受体Fas阳性率由(9.35±0.21)%升高到(21.30±1.27)%(P<0.05)。甲异靛可活化HL-60细胞的caspase-8、caspase-9、caspase-3和PARP,降低抗凋亡蛋白bcl-2的表达和上调促凋亡蛋白bax,并升高细胞浆中细胞色素c的浓度。caspase-3抑制剂(z-DEVD-fmk)可以减少甲异靛对HL-60细胞的增殖抑制,降低细胞凋亡率。100μmol/Lz-DEVD-fmk预处理HL-60细胞后再加入20μmol/L甲异靛,5h后凋亡率为(16.5±5.5)%,甲异靛组为(29.8±5.4)%(P<0.05);12h后计数,抑制剂加甲异靛组活细胞高达(3.57±0.18)×105/ml,甲异靛组活细胞仅为(1.80±0.14)×105/ml(P<0.05)。结论:甲异靛可诱导HL-60细胞凋亡,其机制与caspases和bcl-2家族蛋白的调节有关。

Inducement effect of Meisoindigo on apoptosis of leukemia cell line HL-60 and its mechanism

BACKGROUND & OBJECTIVE: Meisoindigo is a powerful drug used in treating chronic myeloid leukemia (CML), but little is known about the mechanisms. This study was to investigate the inducement effect of meisoindigo on apoptosis of myelocytic leukemia cell line HL-60, and explore the possible mechanisms. METHODS: After treatment of meisoindigo, the proliferation of HL-60 cells was detected by trypan blue exclusion assay, and DNA fragmentation by agarose electrophoresis; cell morphology was observed under fluorescent microscope. Cell apoptosis and the expression of Fas were detected by flow cytometry. The expression of Caspase-3, Caspase-8, Caspase-9, PARP, Bcl-2, Bax and the concentration of cytochrome c in cytosol were analyzed by Western blot. RESULTS: Meisoindigo inhibited proliferation and induced apoptosis in HL-60 cells. When treated with 20 micromol/L meisoindigo for 12-48 h, the proliferation of HL-60 cells was significantly inhibited. When treated for 1 h, the apoptosis rate of HL-60 cells was (3.70+/-0.56)%; the apoptosis rate was significantly higher in HL-60 cells treated for 3, 6, and 12 h than in control cells [(19.80+/-1.13)%, (29.20+/-2.69)%, and (47.05+/-7.70)% vs. (2.65+/-0.78)%, P<0.05]. When treated with meisoindigo for 3 h, typical changes of apoptosis, such as chromatin condensation and DNA ladder, were detected in HL-60 cells. The positive rate of Fas was significantly higher in cells treated with 20 micromol/L meisoindigo for 1 h than in control cells [(21.30+/-1.27)% vs. (9.35+/-0.21)%, P<0.05]. Meisoindigo activated Caspase-3, Caspase-8, Caspase-9 and PARP, down-regulated the expression of Bcl-2, up-regulated the expression of Bax and the concentration of cytochrome c. Furthermore, pretreatment of caspase-3 inhibitor z-DEVD-fmk partially reversed the inhibitory effect of meisoindigo on cell proliferation, and decreased cell apoptosis; when treated with meisoindigo for 5 h, the apoptosis rate was significantly higher in pretreated cells than in cells without pretreatment [(29.8+/-5.4)% vs. (16.5+/-5.5)%, P<0.05]; when treated with meisoindigo for 12 h, the alive cell number was significantly lower in pretreated cells than in cells without pretreatment [(1.80+/-0.14) x 10(5)/ml vs. (3.57+/-0.18) x 10(5)/ml, P<0.05]. CONCLUSION: Meisoindigo induces apoptosis of HL-60 cells which may relate to regulation of caspases pathway and bcl-2 family proteins.