Objective: To investigate the impact of promoter CpG island methylation on ABO mRNA expression in leukemia. Methods: 25 cases of leukemia and 20 cases of normal control were studied, and the leukemia cell lines K562、HL-60 and Jurkat were treated with different concentrations of decitabine. PCR-SSP was used to identify ABO genotype, RQ-PCR for ABO mRNA expression and bisulfite sequencing PCR for DNA methylation status. Results: ① The methylation of ABO promoter in acute myeloid leukemia patients (10 cases) and acute lymphoblastic leukemia patients (10 cases) were 53.85% and 18.22% respectively, which were obviously higher than those in control (20 cases, 2.33%) and chronic myeloid leukemia patients (5 cases, 2.12% ). ② ABO genotype of K562 was O1O1, which has changed little before and after decitabine treatment. ABO genotype of HL-60 and Jurkat could not been identify before treatment, but showed as O1A1 and A1O2 after treatment. ③ABO mRNA expression of K562 was 1 275.67 ± 35.86, which was obviously higher than that in HL-60 (0.54 ± 0.07, P<0.05) and Jurkat (0.82±0.16, P<0.05). ④The methylation of ABO promoter in K562, HL-60 and Jurkat were 0, 58.14%, and 96.74%. As concentration of decitabine increased, the methylation of ABO promoter were decreased and the expressions of ABO mRNA were increased in HL-60 and Jurkat, which had significant differences compared with that before treatment (P<0.05). Conclusion: The methylation of ABO promoter shows a negative correlation with ABO mRNA expression. DNA methylation was an important aspect of ABO antigens decrease in acute leukemia.
目的: 探讨白血病ABO基因启动子区CpG岛甲基化对ABO基因表达的影响。
方法: 以25例白血病患者及20名健康对照者为研究对象，同时以不同浓度去甲基化药物地西他滨处理白血病细胞株K562、HL-60和Jurkat细胞，采用序列特异性引物PCR (PCR-SSP）法检测ABO基因分型，采用实时荧光定量PCR法检测ABO mRNA表达，采用亚硫酸氢盐测序法检测ABO基因启动子区CpG岛甲基化情况。
结果: ①急性淋巴细胞白血病组（10例）和急性髓系白血病组（10例）ABO基因启动子平均甲基化率分别为53.85％和18.22%，明显高于健康对照组（20名，2.33%）和慢性髓性白血病组（5例，2.12%）。②K562细胞的ABO基因型为O1O1，药物作用前后ABO基因型变化不大；HL-60和Jurkat细胞药物作用前基因型无法辨认，药物作用后ABO基因型为O1A1和A1O2。③K562细胞ABO mRNA相对表达水平为1 275.67±35.86，明显高于HL-60和Jurkat细胞（0.54±0.07和0.82±0.16）（P值均<0.05）。④K562、HL-60、Jurkat细胞ABO基因启动子区甲基化率分别为0、58.14％和96.74%；与药物作用前比较，随地西他滨浓度增高，HL-60和Jurkat细胞的甲基化水平下降、ABO mRNA表达水平增高，差异均有统计学意义（P值均<0.05）。
结论: ABO基因启动子区甲基化水平与急性白血病ABO基因表达呈负相关，DNA甲基化导致ABO基因沉默是急性白血病ABO抗原表达减弱的重要机制之一。