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Distal nephron renal tumors: microsatellite allelotype
T J Polascik1, P Cairns, J I Epstein
1James Buchanan Brady Urological Institute, Johns Hopkins University Medical Institutions, Baltimore, Maryland 21287-6101, USA.
Abstract:
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.
Insights
Molecular analysis reveals distinct genetic changes in kidney tumors. Collecting duct carcinomas and renal oncocytomas show specific chromosomal alterations, differing from proximal tubule cancers.
Area of Science:
- Nephrology
- Oncology
- Molecular Biology
Background:
- Renal tumors arise from the nephron's epithelial lining, with proximal tubule cancers (clear cell carcinomas) being well-studied.
- Tumors originating from other renal tubular segments, such as collecting duct carcinomas and oncocytomas, have poorly understood molecular underpinnings.
- Identifying common molecular lesions is crucial for understanding the development and progression of these less-characterized renal tumors.
Purpose of the Study:
- To investigate common molecular lesions in renal tumors originating from the collecting duct.
- To compare the molecular characteristics of collecting duct carcinomas (CDCs) and renal oncocytomas.
- To elucidate the distinct molecular events contributing to non-proximal tubule renal cancers.
Main Methods:
- Detailed microsatellite allelotype analysis was performed on 18 collecting duct carcinomas and 13 renal oncocytomas.
- Highly informative microsatellite markers were used across all autosomal arms to detect loss of heterozygosity (LOH).
- Analysis focused on identifying chromosomal arm alterations specific to each tumor type.
Main Results:
- Loss of heterozygosity (LOH) was observed on multiple chromosomal arms in both CDCs and oncocytomas.
- Significant LOH was found in CDCs on 1q (57%), 6p (45%), 8p (40%), and 21q (40%).
- Renal oncocytomas showed high LOH rates on 1p (57%), 1q (30%), 8p, 14q, 19q, and 21q; LOH on 3p was infrequent in both tumor types.
Conclusions:
- The molecular events driving the development of distal nephron tumors (CDCs and oncocytomas) are distinct from those in proximal tubule renal cancers.
- Specific chromosomal alterations, such as LOH on 1q, 6p, 8p, and 21q in CDCs, and 1p in oncocytomas, characterize these tumor types.
- This study provides insights into the molecular etiology of non-proximal tubule renal tumors, differentiating them from clear cell renal cell carcinomas.