5-杂氮脱氧胞苷去甲基化作用对白血病细胞株HL-60中SHP-1和C-kit基因表达的影响

本研究旨在探讨SHP-1及C-kit基因在急性白血病HL-60细胞中的表达情况及5-杂氮脱氧胞苷（5-azaCdR）去甲基化作用对SHP-1及C-kit表达的影响。用RT-PCR方法检测药物处理组HL-60细胞与对照组SHP-1、C-kit基因的mRNA的表达水平。用甲基化特异性聚合酶链反应（MSP）检测HL-60细胞中SHP-1、C-kit基因的甲基化状态改变。结果表明,在原本不表达SHP-1 mRNA的HL-60细胞中,经过5-aza-CdR的去甲基化作用后,SHP-1可以重新表达,而使原来高表达的C-kit mRNA水平下降。当0.5、1、2μmol/L 5-aza-CdR分别作用于白血病细胞株时,去甲基化作用增强,SHP-1 mRNA的表达水平呈上升趋势,C-kit mRNA的表达水平呈下降趋势,两两比较表明差异有统计学意义（P〈0.05）。结论：HL-60细胞株中SHP-1 mRNA表达缺如,经去甲基化作用后表达恢复,说明SHP-1基因高度甲基化与白血病发生有关;白血病形成中可能存在C-kit mRNA表达的异常增高。5-aza-CdR对SHP-1与C-kit的表达水平的影响呈剂量依赖性,浓度越高,SHP-1平均表达水平越高,C-kit mRNA表达水平越低,在特定的一个浓度下,呈现时间依赖性。SHP-1 mRNA与C-kit mRNA表达呈负相关,提示白血病细胞中SHP-1表达的降低或缺如消弱了对C-kit信号通路的负调控而在白血病形成中发挥作用。

Effect of 5-aza-CdR Demethylation on Expression of SHP-1 and C-kit Genes in Leukemia HL-60 Cells

This study was aimed to investigate the expression level of SHP-1 and C-kit genes in acute leukemia HL-60 cells and effect of 5-aza-CdR demethylation on expression of SHP-1 and C-kit genes.RT-PCR was used to detect the mRNA expression level of SHP-1 and C-kit mRNA in HL-60 cells of the drug-treated group and control group.The methylation specific PCR（MSP）was applied to measure the methylation status of SHP-1 and C-kit genes in HL-60 cells.The results showed that after being treated with 5-aza-CdRthe recovery of SHP-1 gene expression was observed in HL-60 cells in which SHP-1 mRNA originally was not expressed.Meanwhilethe high expressdion level of C-kit mRNA in HL-60 cells was decreased.When HL-60 cells were treated with 0500 μ/L 5-aza-CdRthe demethylation effect was enhancedthe expression of SHP-1 mRNA displayed an ascending tendencyand the expression of C-kit mRNA showed an descending tendency in dose-dependent manner（ P〈0.05）.It is concluded that the absence of SHP-1 mRNA expression in HL-60 cells and recovery of expression after treatment with 5-aza-CdR suggest that the hypermethylation of SHP-1 gene relates with pathogenesis of leukemiaand the abnormal increase of C-kit mRNA expression maybe exist in formation of leukemia.The effect of 5-aza-CdR on expression of SHP-1 and C-kit shows dosedependencythe higher the 5-aza-CdR concentrationthe higher the SHP-1 expression and the lower the C-kit expressionmoreoverthe effect of 5-aza-CdR shows time-dependency in specific concentration.The SHP-1 mRNA expression negatively correlates with C-kit mRNA expressionsuggesting that the decrease or absence of SHP-1expression in leukemia cells weakens the negative regulation on C-kit signaling pathwaythus plays a role in the formation of leukemia.