三氧化二砷通过激活Caspases酶诱导髓性白血病细胞凋亡

目的:明确Caspases酶是否与三氧化二砷(As2O3)诱导的人髓性白血病细胞凋亡有关;明确蛋白激酶C(protein kinase C,PKC)的激活物PMA对As2O3与VP16诱导的细胞凋亡是否有不同的影响.方法:把NB4和HL60细胞株放入有或无Caspases酶抑制剂(Z-VAD.fmk或Y-VAD.Cho)的As2O3中进行培养;凋亡以细胞形态学,DNA梯带和流式细胞分析来评价.多聚的磷酸腺苷聚合酶(poly-ADP-ribose polymerase,PARP)裂解被用作Caspases酶激活的标志.结果:NB4和HL60细胞株在As2O3诱导凋亡的过程中均出现了PARP裂解;Z-VAD.fmk--Caspases酶广谱抑制剂,可以阻断As2O3诱导的细胞凋亡和PARP裂解;但Y-VAD.Cho--Caspases酶的选择性抑制剂,没有此效应;在足以激活PKC的条件下用PMA预培养HL60细胞2～8 h,不论对As2O3还是VP16诱导的凋亡均无明显影响.结论:对于培养的髓性白血病细胞,As2O3诱导细胞凋亡是始自瀑布式激活Caspases酶的远端,通过PARP裂解来实现的.PKC的激活,不论对于As2O3还是VP16诱导的细胞凋亡均无影响.

Arsenic trioxide induces apoptosis of myeloid leukemia cells by activation of caspases

Objective: To determine whether caspases are involved in arsenic trioxide(As 2O 3) induced apoptosis of human myeloid leukemia cells, and whether apotosis induced by As 2O 3 compared to VP16 is differentially affected by an activator of the protein kinase C (PKC), phorbol 12 myristate 13 acetate (PMA). Methods:NB4 and HL60 cells were incubated with As 2O 3 in the presence and absence of the caspase protease inhibitors Z VAD.fmk or Y VAD.Cho. Apoptosis was assessed by morphology, DNA laddering and flow cytometry. Poly (ADP ribose) polymerase (PARP) cleavage was used as a marker for the activation of caspases. Results:PARP cleavage occurred during As 2O 3 induced apoptosis in both NB4 and HL60 cells. Z VAD.fmk, a broad spectrum inhibitor, could block As 2O 3 induced apoptosis and PARP cleavage, while Y VAD.Cho, a selective inhibitor of caspase 1, had no effect. PMA pre incubation for up to 8 hours under conditions known to activate PKC had no effect on either As 2O 3 or VP16 induced apoptosis. Conclusion: In cultured myeloid leukemia cells As 2O 3 induced apoptosis was executed by caspases from the distal, PARP cleaving part of the activation cascade. PKC activation has no effect on apoptosis induced by either As 2O 3 or VP16 in these cells.