Evidence for Two Bladder Cancer Suppressor Loci on Human Chromosome 9

Most carcinomas of the bladder show loss of heterozygosity for markers on human chromosome 9, which suggests that one or more tumor suppressor genes are located on this chromosome. Several observations suggest that such alterations are an important early step in tumorigenesis. We analyzed the pattern of allelic loss in 46 primary carcinomas of the bladder using 19 polymorphic markers from chromosome 9. While most tumors with allelic loss showed loss of heterozygosity for all informative markers that were tested, six tumors demonstrated only partial loss of chromosome 9. Two tumors with partial loss contained deletions that predominately involved the q arm, as shown by previous studies. The other four tumors contained deletions that predominately or exclusively involved the p arm, with a common region of loss between D9S161 (9p21) and the telomere. The results show that there is no single common region of loss on chromosome 9 and identify two distinct regions of loss that may contain bladder tumor suppressor loci.