Isolation of Kidney Complementary DNAs Down-expressed in Wilms' Tumor by a Subtractive Hybridization Approach

We applied a subtractive hybridization approach to isolate genes dif ferentially expressed between mature kidney and Wilms' tumor. We con structed a complementary DNA library from a total mature kidney com plementary DNA subtracted by an excess of mRNA from a Wilms' tumor, WAGR4, with a germline deletion of Hpl3 and a somatic loss of alA­elesat Ilpl5. Six clones presenting a differential pattern of expression, positive with mRNA from the mature kidney and negative with mRNA from the Wilms' tumor WAGR4, were characterized. Among these clones were two as yet unknown expressed sequences (D11S877E and D15S109E) and four sequences from known genes: renal dipeptidase (DPEP1), aB-crystallin (CRYA2), uromodulin il MOI», and plasma glutathione peroxidase (GPX2). The different patterns of expression of these genes in 11 Wilms' tumors, whether or not they are hereditary, reflect the well-documented pathogenetic heterogeneity for Wilms' tumors. We propose that these