Localization of tumor suppressor loci on chromosome 9 in primary human renal cell carcinomas

To investigate the potential loss of tumor suppressor gene loci on chromosome 9 in human renal cell tumorigenesis we analyzed 42 paired normal and tumor DNAs with 18 polymorphic microsatellite markers spanning this chromosome. Fourteen of 42 (33%) tumors showed partial or complete deletion of chromosome 9. Deletion mapping provided evidence for the presence of a suppressor locus on both the short and long arm of chromosome 9. Homozygous deletion at 9p21-22 in one renal tumor and a selective deletion of distal 9q in another tumor localized the critical regions. The CDKN2/p16 gene was further investigated as a candidate suppressor locus on 9p21-22 by multiplex PCR, Southern analysis, and exon sequencing. We found no additional cases of homozygous deletion nor any rearrangements or point mutations of CDKN2/p16. This is the first report of 9p loss of heterozygosity, homozygous deletion of 9p21-22 and selective deletion of 9q in primary renal cell carcinomas. Understanding the molecular genetic basis of renal cell progression will require the isolation and characterization of additional tumor suppressor genes on chromosome 9.