Comparative genomic hybridization reveals frequent chromosome 13q and 4q losses in renal carcinomas with sarcomatoid transformation.

Renal cell carcinomas (RCCs) with sarcomatoid transformation show the most malignant behaviour of all renal carcinoma types. In this study, comparative genomic hybridization was used to screen for losses and gains of DNA sequences along all chromosome arms in 12 sarcomatoid (S) RCCs. On average, there were 8.6 aberrations per tumour. DNA sequence losses (5.2 +/- 4.4) were slightly more frequent than gains (3.4 +/- 2.6). DNA gains most often involved chromosomes 17 (33 per cent), 7, and 8q (25 per cent each). High-level co-amplification involving 11q22-23 and 7p21-22 in one SRCC was not present in adjacent non-sarcomatous tumour areas, raising the possibility of oncogene involvement at these loci for sarcomatoid transformation. DNA losses were most prevalent at 13q (75 per cent) and 4q (50 per cent), suggesting that inactivation of tumour suppressor genes at chromosomes 13q and 4q may be linked to sarcomatoid growth of RCC. It is concluded that SRCCs are genetically highly complex. Chromosomes 13q, 4q, 7p21-22, and 11q22-23 may carry genes with relevance for sarcomatoid growth in RCC.