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目的：探讨不同浓度 DNA 甲基化抑制剂5-氮杂-2-脱氧胞苷对母系表达基因3（ MEG3）基因启动子超甲基化的逆转作用，以及恢复MEG3表达对上皮性卵巢癌细胞增殖活性的影响。方法以0、1、5、10、20μmol／L的5-氮杂-2-脱氧胞苷作用上皮性卵巢癌OVCAR3细胞6 d后，采用甲基化特异性PCR（MSP）检测MEG3启动子的甲基化状态，逆转录聚合酶链反应（RT-PCR）检测MEG3 mRNA的表达水平，采用四甲基偶氮唑蓝（MTT）比色法和5-乙炔基-2′-脱氧尿嘧啶核苷（EdU）掺入实验检测细胞增殖活性的变化。结果 MSP 检测显示，0μmol／L 5-氮杂-2-脱氧胞苷组（对照组）、1μmol／L 5-氮杂-2-脱氧胞苷组5、μmol／L 5-氮杂-2-脱氧胞苷组、10μmol／L 5-氮杂-2-脱氧胞苷组和20μmol／L 5-氮杂-2-脱氧胞苷组的甲基化水平分别为1．00±0．00、0．79±0．00、0．67±0．00、06．5±0．03和0．61±0．01，各组间差异均有统计学意义（均P＜0．05）。RT-PCR检测显示，对照组、1μmol／L 5-氮杂-2-脱氧胞苷组、5μmol／L 5-氮杂-2-脱氧胞苷组、10μmol／L 5-氮杂-2-脱氧胞苷组和20μmol／L 5-氮杂-2-脱氧胞苷组MEG3 mRNA的相对表达水平分别为1．00±0．00、2．04±0．16、2．44±0．17、3．19±0．34和5．34±0．39，各组间差异均有统计学意义（均P＜0．05）。 MTT比色法检测显示，与对照组比较，1μmol／L 5-氮杂-2-脱氧胞苷组、5μmol／L 5-氮杂-2-脱氧胞苷组、10μmol／L 5-氮杂-2-脱氧胞苷组和20μmol／L 5-氮杂-2-脱氧胞苷组OVCAR3细胞的增殖活性受到明显抑制，5-氮杂-2-脱氧胞苷作用2、4、6 d时，各组间细胞抑制率差异均有统计学意义（均P＜0．01）。 EdU掺入实验显示，对照组、1μmol／L 5-氮杂-2-脱氧胞苷组、5μmol／L 5-氮杂-2-脱氧胞苷组、10μmol／L 5-氮杂-2-脱氧胞苷组和20μmol／L 5-氮杂-2-脱氧胞苷组OVCAR3细胞中的EdU阳性细胞率分别为（40．78±0．80）％、（35．65±0．33）％、（31．81±0．66）％、（27．33±1．27）％和（17．75±1．85）％，差异均有统计学意义（均P＜0．01）。结论5-氮杂-2-脱氧胞苷可逆转上皮性卵巢癌细胞抑癌基因MEG3启动子超甲基化状态，进而使MEG3重新表达，从而参与了抑制卵巢癌细胞的增殖活性。

O bjce tive To investigate the reversal effects of different concentrations of DNA methylation inhibitor, 5-aza2--deoxycytidine, on the hypermethylation of maternally expressed gene 3 ( MEG3) gene promoter,and then the inhibitory effect of restoration of MEG 3 expression on the proliferation of ovarian cancer cells.Methods Human ovarian cancer OVCAR3 cells were treated with various concentration of 5-aza-2-deoxycytidine ( 0, 1, 5, 10, 20 μmol/L, respectively ) for 6 days.Then the methylation status of MEG3 promoter was detected by methylation specific PCR ( MSP ) .The alteration of&nbsp;MEG3 gene expression was detected by RT-PCR.Cell proliferation was determined by MTT assay and EdU incorporation assay.Resutl s After treated with 5-aza-2-deoxycytidine, the methylation status of MEG3 in the 0, 1, 5, 10,20 μmol/L5 -aza-2-deoxycytidine groups were 1.00±0.00, 0.79±0.00, 0.67±0.00, 0.65± 0.03 and 0.61±0.01 folds, respectively ( P<0.05 for all) .The relative expressions of MEG3 mRNA in the 0, 1, 5, 10, 20μmol/L 5-aza-2-deoxycytidine groups were 1.00±0.00, 2.04±0.16, 2.44±0.17, 3.19±0.34 and 5.34±0.39, respectively ( P<0.05 for all) .In contrast to the negative control, the inhibition rates of the OVCAR3 cell growth were increased significantly when treated with 1, 5, 10, 20 μmol/L 5-aza-2-deoxycytidine in 2, 4 and 6 days.There were ( 40.78 ±0.80)%, ( 35.65 ±0.33)%, ( 31.81 ±0.66)%, (27.33±1.27)%and (17.75±1.85)%of EdU-positive cells in the 0, 1, 5, 10 and 20 μmol/L 5-aza-2-deoxycytidine groups ( P <0.01 for all ) . Conclusions Maternally expressed gene 3 promoter hypermethylation is reversed by 5-aza2--deoxycytidine in ovarian cancer cells.The downregulation of MEG3 gene might be resulted from the methylation, and the re-expression of MEG3 partly contribute to the growth inhibition of epithelial ovarian cancer cells.