Fluorescence Quantitative PCR Detection Of WT1 Gene Expression In Leukemias And Its Clinical Implications

Objective: To establish a fluorescence quantitative RT-PCR(FQ-RT-PCR)method for detection of WTl gene expression .To elucidate the expression of WTl in all types of leukemias and its implications for monitoring minimal residual disease in acute leukemia. Method: The conventional RT-PCR was used to amplify WT1 gene and β-actin gene from K562 cells. After gel extraction,purification and quantification by a photometer, quantitative stand template was constructed. Using FQ-RT-PCR,we measured the peripheral blood or bone marrow samples from 80 leukemia patients and 10 normal voluteer's peripheral blood samples.Long-term follow-up monitoring of WT1 expression of peripheral blood was performed for 15patients with acute leukemia. Statistics were performed using SPSS software.Results: We could not find significant difference in the paired peripheral blood and bone marrow samples from 10 newly diagnosed acute leukemia patients with respect to the expression of WT1 gene.The expression of WT1 gene in all types of leukemias was significantly higher than that in normal controls. WT1 expression levels was significantly higher in myeloid than in lymphoid.Patients with M5 expressed significantly lower levels.No association was found between WT1 expression levels and sex,initial leukocyte count and karyotype. Patients with a high level of WT1 expression had a significantly lower complete remission rate and worse overall survival. Long-term follow-up detection the expression of WTl in peripheral blood samples from 15 acute leukemia patient,4 cases relapsed after complete remission has been achieved for 3-7 months.In2 of 4 relapsed patients, the expression of WT1 had increased obviously about 1-2 months before clinical relapse became apparent.There was no obvious change of WT1 expression level at any point of treatment in three chemoresistant to induction treatment patients. Conclusion: The established FQ-RT-PCR method is sensitive and specific .The expression of WT1 gene was relatively high in all types of leukemias compared with normal peripheral blood cells,and dynamics of WT1 level correlated with the disease status. The quantitative assessment of WT1 expression in peripheral blood samples by FQ-RT-PCR may be a useful tool for monitoring minimal residual disease.