Wilms' Tumor (WT1) Gene Expression and Acute Childhood Leukemia

Abstract

Wilms' tumor gene (WT1) plays an important role in leukemogenesis and has an oncogenic function rather than a tumor suppressing function in hematopoietic progenitor cells (Inoue et al, 1998). In this study, WTI expression was detected in children with acute leukemia; to evaluate its prognostic value and its relevance as a genetic marker for detection of minimal residual blast cells. RT-PCR was used to examine relative levels ofWTI transcripts from the peripheral blood of 58 children diagnosed with acute leukemia: 33 were newly diagnosed (10 ANLL, 19 ALL & 4 ABL), 8 relapsing patients (2 ANLL, 4 ALL, 2 ABL) and 17 patients were in •remission (6 ANLL & 11 ALL). Ten children were studied for controls (7 normal and 3 with leukomoid blood picture). WTI mRNA were not expressed at detectable levels in nonnal individuals nor in those with leukomoid reaction but the gene transcripts were expressed in most patients in various stages of leukemia. The highest levels of WT I transcripts were detected in relapsing AL children, while lower levels were expressed in newly diagnosed patients. On the other hand, patients in remission showed the least levels and was even undetected in 5 patients. The levels of gene expression were higher in ANLL than ALL & ABL. Furthermore, following up of 1 0 WT1-positive patients in remission showed a decrease in WT1 expression to• low levels while the values were increased during relapse. Moreover, all patients with high risk prognostic factors express high levels of WT1 >I X 1o-2' while those of low risk group the WT1 transcripts were