Cross-sectional monitoring of Wilms' tumor gene 1 (WT1) expression in Iranian patients with acute lymphoblastic leukemia at diagnosis, relapse and remission.

Wilms' tumor gene 1 (WT1) is a universal tumor-associated antigen (TAA) expressed in a variety of malignancies. High WT1 mRNA expression has been detected in the majority of acute leukemias and has been identified as a convenient marker for disease monitoring. The aim of this study was to evaluate WT1 expression in Iranian ALL patients at diagnosis, relapse and remission. WT1 mRNA was detected in leukemic cells of ALL patients obtained at diagnosis (n = 62), relapse (n = 19) and remission (n = 35) using a semi-quantitative RT-PCR method. In addition, peripheral blood samples from 36 healthy donors were included as controls. Only 3 out of 36 normal samples gave a weak WT1 mRNA band and the ratio of WT1 to beta-actin band densities was calculated to obtain an arbitrary cut-off value for analysis of WT1 gene expression in patients. On the basis of the baseline value, leukemic cells from 51.6% (32/62) of the newly diagnosed patients and 57.9% (11/19) of the relapsed patients were WT1 positive; however, all of the patients in remission (35/35) were WT1 negative. WT1 expression in newly diagnosed and relapsed ALL patients was significantly higher than that of the ALL patients at remission and normal subjects (p < 0.0001). Our results indicate that WT1 could be employed as a reliable TAA to monitor minimal residual disease in Iranian patients with ALL.