Wilms tumor gene expression in acute myeloid leukemias.

The Wilms' tumor gene product (WT-1) is suggested to act as a tumor suppressor in childhood malignancies of the kidney and as a transcription factor with regulating activity on a number of growth and differentiation factors. Wt-1 has been shown to be expressed in blast cells of the vast majority of patients with acute myeloid and lymphoblastic leukemias (AL) by a number of workers. High levels of wt-1 mRNA expression in blast cells of newly diagnosed AML patients predict worse prognosis when compared to patients with no or low wt-1 mRNA expression. Patients achieving complete responses after chemotherapy usually lose detectable signals of wt-1. In relapse of the disease reoccurrence of wt-1 mRNA can be determined in almost all patients with initially detectable wt-1 mRNA. Using sensitive techniques such as reverse transcription polymerase chain reaction (RT-PCR) relapses are preceded by wt-1 expression in some cases. Although a subpopulation of normal hematopoietic precursor cells has also been shown to express message for wt-1, detectable levels of wt-1 during follow-ups in AML patients have been shown to be useful as a marker for residual blast populations or even to predict relapse of AML. Whether the high level of wt- expression is a non-specific phenomenon resulting from malignant transformation or whether it has an impact on the pathophysiology of AML or the uncontrolled growth of AML blasts is still controversial. However, there are indicators for an involvement of wt-1 in malignant events of AML blasts such as the downregulation of wt-1 in chemically induced differentiation of AML blast cell lines or the interactions of wt-1 with the protooncogene bcl-2 and the tumor suppressor gene p53. In conclusion, its possible relevance as an AML marker and its role in pathophysiological mechanisms in AML will still have to be defined in the future.