Objective: To investigate the mechanism by which epigallocatechin gallate (EGCG) induces CHD5 gene demethylation and promotes the apoptosis of acute myeloid leukemia KG-1 and THP-1 cell lines.
Methods: KG-1 and THP-1 cells treated with 25, 50, 75, 100 or 150 μg/mL EGCG for 48 h were examined for CHD5 gene methylation using MSP and for cell proliferation using MTT assay. The changes in cell cycle and apoptosis of the two cell lines after treatment with EGCG for 48 h were detected using flow cytometry. The mRNA and protein expressions of DNMT1, CHD5, p19Arf, p53 and p21Cip1 in the cells were detected using RT-quantitative PCR and Western blot.
Results: EGCG dose-dependently reversed hypermethylation of CHD5 gene and reduced the cell viability in both KG-1 and THP-1 cells (P < 0.05). EGCG treatment caused obvious cell cycle arrest in G1 phase, significantly increased cell apoptosis, downregulated the expression of DNMT1 and upregulated the expressions of CHD5, p19Arf, p53 and p21Cip1 in KG-1 and THP-1 cells (P < 0.05).
Conclusions: EGCG reduces hypermethylation of CHD5 gene in KG-1 and THP-1 cells by downregulating DNMT1 to restore its expression, which results in upregulated expressions of p19Arf, p53 and p21Cip1 and induces cell apoptosis.
目的: 探讨表没食子儿茶素没食子酸酯（EGCG）诱导CHD5基因去甲基化促进KG-1、THP-1细胞凋亡的相关机制。
方法: 设实验组及正常对照组，实验组：不同浓度（25、50、75、100、150 μg/mL）EGCG处理作用于KG-1、THP-1细胞，正常对照组：不加EGCG处理。MSP法检测KG-1、THP-1细胞CHD5基因甲基化；MTT法检测作用48 h后细胞增殖；流式细胞术检测作用48 h后细胞周期和细胞凋亡状况；RT-qPCR、Western blot检测DNMT1、CHD5、p19Arf、p53、p21Cip1基因和蛋白表达。
结果: EGCG呈现剂量依赖性逆转了KG-1、THP-1细胞CHD5基因高甲基化；EGCG以剂量依赖性的方式抑制KG-1、THP-1细胞增殖（P < 0.05）；EGCG诱导细胞周期停滞于G1期，促进细胞凋亡；EGCG以剂量依赖性的方式下调DNMT1的mRNA和蛋白表达，上调CHD5、p19Arf、p53、p21Cip1的mRNA和蛋白表达（P < 0.05）。
结论: EGCG可通过下调DNMT1降低KG-1、THP-1细胞CHD5基因高甲基化，恢复CHD5基因表达，从而上调p19Arf、p53、p21Cip1表达诱发细胞凋亡。
Keywords: CHD5 gene; acute myleoid leukemia; epigallocatechin gallate; methylation; p19Arf-p53-p21Cip1 signaling pathway.