Objective To observe the effect of curcumin on DNA methyltransferase (Dnmts) activity and tumor sup-pressor gene human H-cadherin (CDH13) in non-small-cell lung cancer (NSCLC) A549 cells and to explore the mecha-nism of curcumin's demethylation .Methods A549 cells were divided into two groups:the observation group and the con-trol group.Cells in the observation group were cultured with 40 μmol/L curcumin and the culture medium , while cells in the control group only with the culture medium .MTT assay was used to detect the cell proliferation , and RT-PCR was used to detect the expression of CDH 13 mRNA.CpG island methylation status of CDH 13 promoter was detected by methylation-specific PCR ( MSP) , and catalytic activity of Dnmts was detected by enzyme colorimetric determination kit .Results The OD of the observation group was 0.638 ±0.184, which was lower than that (0.859 ±0.040) of the control group (P<0.05).The relative expression level of CDH13 mRNA in the observation group was 0.64 ±0.09, which was higher than that (0.43 ±0.12) of the control group.There were methylation amplification bands , but no demethylation bands in the control group, and there were both methylation amplification bands and demethylation bands in the observation group .In the observation group and the control group , the activities of Dnmt1 were separately (0.153 ±0.016) and (0.770 ± 0.014) μmol/min, and the activities of Dnmt3b were (0.137 ±0.020) and (0.179 ±0.013) μmol/min, respectively. The activities of Dnmt1 and Dnmt3b in the observation group were lower than those in the control group (all P<0.05). Conclusion Curcumin inhibits the methylation status of CDH 13 by decreasing the activity of Dnmts , and thereby inhibits A549 cell proliferation .%目的：观察姜黄素对非小细胞肺癌（ NSCLC） A549细胞DNA甲基化转移酶（ Dnmts）活性和抑癌基因人H-钙黏蛋白（ CDH13）的影响，探讨姜黄素的去甲基化机制。方法将A549细胞分为两组，观察组加入40μmol／L姜黄素和培养液，对照组仅加入培养液。采用MTT法检测两组细胞增殖能力，RT-PCR方法检测CDH13 mRNA表达，甲基化特异性PCR （ MSP ）检测 CDH13启动子 CpG 岛的甲基化状态，酶活性连续循环比色法检测 Dnmt1、Dnmt3b活性。结果观察组和对照组的细胞增殖OD值分别为0．638±0．184、0．859±0．040，观察组低于对照组（P＜0．05）。两组CDH13 mRNA的相对表达量分别为0．64±0．09、0．43±0．12，观察组高于对照组（P＜0．05）。对照组出现甲基化扩增条带，无去甲基条带；观察组除甲基化条带外，出现去甲基化条带。观察组和对照组每mg核蛋白中Dnmt1的活性分别为（0．153±0．016）、（0．770±0．014）μmol／min，Dnmt3b的活性分别为（0．137±0．020）、（0．179±0．013）μmol／min，观察组Dnmt1、Dnmt3b活性均较对照组下降（P均＜0．05）。结论姜黄素可通过降低Dnmts活性来抑制CDH13的甲基化状态，从而抑制A549细胞增殖。
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