Molecular characterization of congenital mesoblastic nephroma and its distinction from wilms Tumor

Abstract

BACKGROUND: Congenital mesoblastic nephroma (CMN) is a rare tumor of the neonatal kidney. It was once thought to be a variant of Wilms tumor that also arises from primitive renal cells. METHODS: Molecular characteristics of two CMN were studied to clarify their potential relationship to Wilms tumors. Patterns of gene expression were assayed by Northern blot hybridization analysis. Tumors were tested for loss of heterozygosity (LOH) at chromosomes 11p13 and 11p15 using Southern blot analysis. RESULTS: The CMN, like Wilms tumors, demonstrated high-level expression of insulin-like growth factor II. Unlike Wilms tumors, however, the CMN expressed neither the N-myc oncogene nor the putative Wilms tumor suppressor gene, WT1. Using a panel of probes spanning 11p13 and 11p15, no LOH was detected in the CMN, nor was there evidence of deletion or rearrangements of WT1. CONCLUSIONS: Although Wilms tumor and CMN both arise from the developing kidney, molecular characterization suggests that different factors are involved in the pathogenesis of these two tumors.