酪氨酸激酶抑制剂通过下调Mcl-1和Bcl-xl诱导K562细胞凋亡

STI571 Induces Apoptosis of K562 Cells through Down-regulation of Anti-apoptotic Protein Mcl-1 and Bcl-xl Expression

本研究观察酪氨酸激酶抑制剂STI571对CML细胞增殖和凋亡以及抗凋亡蛋白Mcl-1表达的影响,探讨Mcl-1在BCR/ABL抗凋亡信号传导中的作用。应用STI571处理慢性髓系白血病K562细胞株,采用台盼蓝拒染法和MTT法检测STI571对K562细胞增殖的影响,用Annexin V和碘化丙锭双染法及流式细胞术检测K562细胞凋亡情况,蛋白印迹法检测STI571对细胞内蛋白酪氨酸磷酸化水平和凋亡相关蛋白表达的影响。结果发现:STI571可有效地抑制K562细胞增殖并诱导K562细胞凋亡,这种作用呈剂量和时间依赖性,同时降低细胞内蛋白酪氨酸磷酸化水平和下调抗凋亡蛋白Mcl-1和Bcl-xl的表达。STI571抑制K562细胞增殖和诱导凋亡与抗凋亡蛋白Mcl-1和Bcl-xl的表达下调一致。结论:STI571通过阻断CML细胞内信号传导途径,下调Mcl-1和Bcl-xl的表达,抑制K562细胞增殖并诱导凋亡,表明Mcl-1和Bcl-xl一起在CML抗凋亡过程中发挥重要作用。

This study was aimed to investigate the effect of STI571, an inhibitor of tyrosine kinase, on the proliferation and apoptosis of chronic myelogenous leukemia （CML） cells as well as expression of anti-apoptotic protein Mcl-1, and to explore the possible role of Mcl-1 in apoptosis-inducing mechanism. K562 cell line was used to observe the effect of STI571 on CML cells. Proliferation and cytotoxity were analyzed by MTF assay. The apoptoic cells were labelled with Annexin V-FITC and PI and then analyzed by flow cytometry. The expression of apoptotic-related proteins in K562 cells was determined by Western blot with specific antibodies. The results showed that STI571 significantly inhibited the proliferation and induced apoptosis of K562 cells in a dose-and time-dependent manner. Coincidently, the protein phosphorylation on tyrosine residues was reduced and the expressions of anti-apoptotic protein Mcl-1 and Bcl-xl were downregulated after exposure to STI571. It is concluded that ST1571 induces the apoptosis of CML cells by down-regulating the expressions of Mcl-1 and Bcl-xl, which suggests that Mcl-1 and Bcl-xl may play an important role in anti-apoptotic process of CML cells.