[Expression of WT1mRNA: relation to histology in Wilm's tumor]

The mRNA expression of WT1 gene was examined by Northern blot and Dot blot hybridization in 13 Wilm's tumors of varying histology, 2 normal kidneys (1 and 5 years of age) and 1 fetal kidney (5 months of gestation).

(1) WT1 gene expression was much higher in fetal kidney than in normal kidney of children; (2) Wilm's tumors which were predominantly epithelial or blastemal expressed high amounts of WT1mRNA, whereas predominantly stromal tumors expressed low amounts (P < 0.01). The data suggests that (1) there is a relationship between WT1 gene expression and cellular differentiation in kidney development; (2) low level expression of WT1mRNA results in disruption of cell differentiation and development of Wilms' tumor which shows stromal-predominant histology.