中文摘要：

目的：观察地西他滨（DAC）抑制白血病K562细胞生长和诱导分化的作用。方法：不同浓度的DAC处理K562细胞。MTT法和半固体集落生成实验检测K562细胞增殖能力;瑞氏染色观察细胞形态;流式细胞术检测分化相关抗原CD11b和CD42b阳性表达率;Western blot检测细胞周期蛋白依赖性激酶2（CDK2）、细胞周期蛋白E1（cyclin E1）、细胞周期负调控因子P27、红系分化核转录因子GATA-1及粒系分化核转录因子PU.1蛋白的表达水平。结果：DAC能够减少K562细胞集落形成的数量,降低细胞活力,减少核质比,抑制K562细胞进入S期,并阻滞在G2/M期,提高分化相关抗原CD11b和CD42b阳性表达率,上调P27、GATA-1和PU.1蛋白表达,同时下调CDK2和cyclin E1蛋白表达。结论：DAC可能通过调控细胞周期抑制K562细胞增殖,同时诱导多向分化。

英文摘要：

AIM：To investigate the effect of decitabine（Dacogen,DAC） on the proliferation and differentiation of K562 cells.METHODS：The K562 cells were treated with different concentrations of DAC.The colony formation ability of the cells was detected by the colony formation assay with semi-solid culture.The cell viability was detected with MTT assay.The morphologic features were observed under inverted microscope with Wright’ s staining.The changes of the cell cycle distribution and the expression of CDllb and CD42 b were analyzed with flow cytometry.The protein expression of CDK2,cyclin El,P27,GATA4 and PU.1 in the K562 cells was determined by Western blot.RESULTS：DAC significantly decreased the colony number of the cells and cell viability in a dose-dependent manner.The morphological changes of the cells displayed partial differentiation.After treated the K562 cells with DAC for 72 h,the cell proportion in S phase was obviously decreased,while the cell proportion in G2/M phase was obviously increased in a dose-dependent manner.After treated the K562 cells with DAC for 7 d,the percentage of CD11 b and CD14 positive cells was further elevated,and the protein expression of P27,GATA-1 and PU.1 was increased.However,the protein expression of CDK2 and cyclin El was decreased.CONCLUSION：DAC inhibits the proliferation and induces differentiation of the K562 cells via regulation of cell cycle.