定量检测WT1基因表达水平在急性髓系白血病微量残留病监测中的意义

目的评价定量检测WT1基因表达水平在监测急性髓系白血病（AML）微量残留病（MRD）中的意义．方法采用实时定量RT-PCR（RQ-PCR）技术分别测定了15名正常人骨髓及72例AML患者治疗前后123份骨髓标本WT1基冈mRNA表达水平，同时对62份患者标本定量检测了AML1-ETO融合基因mRNA表达水平，对跟踪观察的8例患者50份标本同时监测了WT1及AML1-ETO基因mRNA水平变化。WT1及AML1-ETO基因表达水平用内参照基因ABL归一化。结果WT1、AML1-ETO及ABLRQ-PCR的标准曲线相关系数均〉0．99，日内差及日间差均〈4％。正常骨髓WT1mRNA中位水平为0．008（0．001～0．019）。67例初治AML患者中61例（91．0％）WT1mRNA表达高于正常水平，其中37例（55．2％）高于正常100倍以上。各型AML中M4EO及M3患者WT1mRNA水平最高，明显高于其他亚型，M1及M5型最低。WT1与AML1-ETOmRNA水平明显正相关（r=0．88，P〈0．001），4例血液学持续缓解患者中3例WT1mRNA水平始终在正常范同内波动。4例发生血液学复发的患者中3例复发前1个月WT1mRNA的水平分别超出正常上限的31.4，11.4及4.0倍。结论RQ-PCR定量检测WT1mRNA水平可用于监测大多数AML患者MRD，但是敏感度不如AML1-ETO融合基因，WT1mRNA水平持续增高或明显异常预示复发。

Significance of quantification of WT1 mRNA for monitoring minimal residual disease in acute myeloid leukemia patients

Objective To evaluate the significance of quantification of WT1 mRNA for monitoring minimal residual disease(MRD) in patients with acute myeloid leukemia(AML). Methods WT1 mRNA level was detected with real-time quantitative RT-PCR (RQ-PCR) technique in bone marrow samples from 15 normal subjects (NBM) and 123 AML patients. Sixty-two AML samples were also detected AML1-ETO mRNA expression by RQ-PCR. Simultaneously follow-up of WT1 and AML1-ETO levels were carried out in 50 samples from 8 AML patients. WT1 and AML1-ETO levels were normalized by internal control ABL gene. Results All correlation coefficiencies were over 0.99 for WT1, AML1-ETO and ABL standard curves. Coefficiencies of both interassay and intraassay variation were below 4%. The WT1 expression levels in NBM were 0.001 to 0.019 with a median level of 0.008. Higher levels of WT1 expression were found in 61 of 67 (91%)newly diagnosed AML patients compared with NBMs and 37 of the 67 (55.2%) showed 100-fold higher WT1 levels than that in NBMs. WT1 mRNA levels were highest in M_ 4EO and M_3 and lowest in M_1 and M_5 patients. There was an excellent correlation between WT1 and AML1-ETO gene expression levels(r= 0.88 ,P<0.001). WT1 expression levels in three patients who were in continous complete hematological remission(CHR) were within normal range. In three of four relapsing patients, WT1 expression levels increased 31.4 ,11.4 and 4.0 fold respectively one month before hematological relapse. Conclusions Quantification of WT1 expression level by RQ-PCR may be used to monitor MRD for most AML patients, but it is less sensitive than fusion gene. Continuous or significant increase of WT1 expression in CHR patients predicts an impending relapse.