骨髓增生异常综合征患者地西他滨治疗后DNA甲基化水平变化

目的 了解骨髓增生异常综合征(MDS)患者地西他滨治疗后DNA甲基化水平的变化.方法 7例MDS患者难治性贫血伴原始细胞增多Ⅰ型或Ⅱ型(RAEBⅠ/Ⅱ)接受规律的地西他滨治疗,5天方案(4例)和3天方案(3例),每个疗程分4个时间点采集其外周血,实时荧光定量聚合酶链反应( real time-Q-PCR)方法检测外周血P15和CDH1基因的甲基化水平.结果 用药前3例患者(例2、例4和例7)P15甲基化水平较高(20％～65％),CDH1均较低(0.5％～5％).无论5天还是3天方案,用药前甲基化水平越高,用药后下降越明显,患者用药第5/7天后P15、CDH1甲基化水平下降幅度最大,达20％～60％,P15可维持在下降后的水平,在随后的治疗中未再出现明显的下降,但是CDH1的波动较大,用药期间CDH1甲基化水平可升至≥用药前水平.目前的数据表明甲基化的变化与血象变化不一致.应用重复测量方法分析5天与3天方案两个基因甲基化水平变化,两种不同方案组间去甲基化水平差异无统计学意义(均P ＞0.05)；有血液学改善的患者与未改善患者的去甲基化程度差异无统计学意义.结论 地西他滨治疗后P15和CDH1的甲基化水平均有不同程度降低,但甲基化水平与治疗方案和疗效无关.

Changes of DNA methylation level of myelodysplastic syndrome patients after decitabine

Objective To analyze the change of DNA methylation level of myelodysplastic syndrome（MDS） patients after seven decitabine. Methods All seven patients of refractory anemia with excess of blast type Ⅰ/Ⅱ（RAEB Ⅰ/Ⅱ） patients received regular therapy of decitabine.Collecting the peripheral blood sample with 4 time points from these patients during the course of 5 days（4 patients） and 3 days（3 patients） schedule treatment.DNA methylation level of P15 and CDH1 in peripheral blood were detected by using real-time fluorescence quantitative polymerase chain reaction. Results Before use of decitabine,the methylation level of P15 was relatively high（20%-65%） from 3 patients（case 2,case 4 and case 7）,and the methylation level of CDH1 was lower（0.5%-5%）.The higher the baseline methylation level was,the more it decreased after decitabine,regardless of 3 days schedule or 5 days schedule.The most decline（20%-60%） of methylation level of P15 and CDH1 appeared in 5/7 days after use of decitabine.During the subsequent treatment,the level of methylation with P15 could maintain at the lower level,while the methylation level of CDH1 was in larger variation,its level can return to baseline or even higher.Currently,our data showed the variations of methylation were not consistent with the hemogram.There were no significant differences in the hepomethylation level between 5 days schedule and 3 days schedule by repeat measured statistic method,the same result was also found in hematological improved group and no improved group. Conclusion The methylation level of P15 and CDH1 of MDS patients after decitabine decreased in various degrees.But there were no significant correlation of the methylation level with therapeutic schedule and treatment outcome.