Distal nephron renal tumors: Microsatellite allelotype

Tumors of varying malignant potential arise from the complex epithelial lining of the nephron. Although the molecular characteristics of renal clear cell carcinomas, which arise from the proximal tubule, have been studied, little is known about tumors that develop from other parts of the renal tubular system. To elucidate common molecular lesions that may contribute to the development or progression of nonproximal tubule renal tumors, we performed a detailed microsatellite allelotype of lesions thought to arise from the renal collecting duct. Eighteen collecting duct carcinomas (CDCs) and 13 renal oncocytomas were studied using highly informative microsatellite markers on all autosomal arms. Loss of heterozygosity (LOH) was identified on multiple chromosomal arms in CDCs and renal oncocytomas. Microsatellite analysis revealed LOH of 1q in 57% of informative CDCs. LOH was also observed on arms 6p (45%), 8p (40%), and 21q (40%). In renal oncocytomas, LOH of 1q occurred in approximately 30% of tumors, but 1p LOH was observed in 57% of informative cases analyzed. High levels of LOH were also observed on arms 8p, 14q, 19q, and 21q in the oncocytomas studied. Loss of chromosomal arm 3p was infrequent in both tumor types. Our results suggest that the molecular events that contribute to the development of distal nephron tumors are distinct from those associated with the etiology of proximal tubule renal cancers.