Overrepresentation of 7q31 and 17q in renal cell carcinomas.

Xenografts from four metastatic renal cell carcinomas (RCCs) were established in immunodeficient mice. All tumors exhibited cytogenetic features specific for the papillary subtype, namely, partial or total polysomy of chromosomes 7 and 17 and integrity of 3p. Cytogenetic analysis of the initial and xenografted tumors indicated that although clonal characteristics were consistently maintained in xenografts derived from metastases, a minor clone had been selected for in the xenografts derived from the primary tumors. Reverse painting and comparative genomic hybridization (CGH) allowed us to localize minimal overrepresented genomic regions to 7q31, where the MET protooncogene is located, and to 17q. Other overrepresented regions were 8q in all xenografts and Xq22-qter in three of them. The gain of genetic material from these regions may be a key factor ensuring the papillary nature of RCCs and their survival in xenografts.