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Objective To observe the effect of curcumin on DNA methyltransferase (Dnmts) activity and tumor suppressor gene human H-cadherin (CDH13) in non-small-eell lung cancer i NSCLC A549 cells and to explore the mechanism of curcumin s demethylation. Methods A549 cells were divided into two groups: the observation group and the control 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 CDH13 mRNA. CpG island methylation status of CDH13 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 gmup. In the observation group and the control group, the activities of Dnmtl 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 Dnmtl 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 CDH13 by decreasing the activity of Dnmts. and thereby inhibits A549 cell proliferation. [ABSTRACT FROM AUTHOR]