髓系白血病细胞中细胞因子信号转导抑制因子1基因启动子去甲基化对细胞增殖、凋亡的影响

Effects of suppressor of cytokine signaling 1 gene promoter demethylation on cell proliferation and apoptosis in myeloid leukemia cells

  • 摘要:
      目的  探讨髓系白血病(ML)细胞中细胞因子信号转导抑制因子1(SOCS-1)基因启动子去甲基化对细胞增殖、凋亡的影响。
      方法  收集78例ML患者的骨髓标本(实验组)以及人ML细胞系U937、HL-60、K562为研究对象,另外收集50例健康捐献者的骨髓标本作为对照组。甲基化特异性聚合酶链反应(MS-PCR)检测ML患者骨髓标本中SOCS-1基因启动子甲基化状态,实时荧光定量聚合酶链反应(qRT-PCR)检测ML患者骨髓标本以及人ML细胞系中SOCS-1 mRNA表达; Western blot检测ML患者骨髓标本以及人ML细胞系中SOCS-1蛋白表达。用0、0.8、1.6、3.2 μmol/L地西他滨(DCA)分别处理U937细胞,并分别命名为空白组、DCA-L组(DCA低剂量)、DCA-M组(DCA中剂量)、DCA-H组(DCA高剂量)。MS-PCR检测各组细胞中SOCS-1基因启动子甲基化状态; qRT-PCR检测各组细胞中SOCS-1 mRNA表达; Western blot检测各组细胞中SOCS-1蛋白表达; CCK-8法检测各组细胞增殖情况; 流式细胞术检测各组细胞凋亡情况。
      结果  SOCS-1在ML患者中呈高甲基化状态, SOCS-1 mRNA及SOCS-1蛋白在ML患者中的表达低于对照组,差异有统计学意义(P < 0.05); 人ML细胞系U937、HL-60、K562中SOCS-1 mRNA及SOCS-1蛋白表达低于人骨髓基质细胞HS-5, 差异有统计学意义(P < 0.05), 且U937细胞中SOCS-1 mRNA及SOCS-1蛋白表达水平最低,因此,以U937细胞为研究对象进行后续实验。与空白组比较, DCA-L组、DCA-M组、DCA-H组中SOCS-1甲基化水平、450 nm处光密度值(OD450 nm)(24、48、72 h)降低, SOCS-1 mRNA及SOCS-1蛋白表达水平、细胞凋亡率升高(P < 0.05), 且随着DCA浓度的升高,上述指标的相应趋势越明显。
      结论  SOCS-1去甲基化可抑制ML细胞增殖、促进细胞凋亡。

     

    Abstract:
      Objective  To investigate the effects of demethylation of the promoter of suppressor of cytokine signaling 1 (SOCS-1) in myeloid leukemia (ML) cells on cell proliferation and apoptosis.
      Methods  The bone marrow specimens of 78 ML patients (experimental group) and the human ML cell lines U937, HL-60 and K562 were collected as research objects, and bone marrow specimens from 50 healthy donors were collected as control group. Methylation-specific polymerase chain reaction (MS-PCR) was used to detect the methylation status of SOCS-1 gene promoter in bone marrow specimens of ML patients, quantitative real-time polymerase chain reaction (qRT-PCR)was used to detect the expression of SOCS-1 mRNA in bone marrow specimens of ML patients and human ML cell lines; Western blot was used to detect the expression of SOCS-1 protein in bone marrow specimens of ML patients and human ML cell lines. U937 cells were treated with 0, 0.8, 1.6 and 3.2 μmol/L Decitabine (DCA), and were selected as blank group, DCA-L group (DCA low-dose), DCA-M group (DCA medium-dose) and DCA-H group (DCA high-dose). MS-PCR was used to detect the SOCS-1 gene promoter methylation status in each group of cells; qRT-PCR was used to detect the SOCS-1 mRNA expression in cells of each group; western blot was used to detect the SOCS-1 protein expression in each group of cells; CCK-8 method was used to detect the cell proliferation in each group; flow cytometry was used to detect the cell apoptosis in each group.
      Results  SOCS-1 was hypermethylated in ML patients, and the expressions of SOCS-1 mRNA and SOCS-1 protein in ML patients were significantly lower than that in the control group (P < 0.05); the expressions of SOCS-1 mRNA and SOCS-1 protein in human ML cell lines U937, HL-60, and K562 was significantly lower than that in human bone marrow stromal cells HS-5 (P < 0.05), and the expression levels of SOCS-1 mRNA and SOCS-1 protein in U937 cells were the lowest, therefore, the U937 cells were used as the research objects for follow-up experiments. Compared with the blank group, the SOCS-1 methylation levels and optical density 450 value (OD450 nm) at 24, 48 and 72 h in the DCA-L group, the DCA-M group and the DCA-H group were significantly reduced, and the SOCS-1 mRNA and SOCS-1 protein expression levels as well as the apoptotic rate were significantly increased (P < 0.05), and the corresponding trend of the above indicators became more obvious with the increase of DCA concentration.
      Conclusion  SOCS-1 demethylation can inhibit the proliferation of ML cells and promote cell apoptosis.

     

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