Homozygous deletion at the 9q32-33 candidate tumor suppressor locus in primary human bladder cancer

Loss of heterozygosity (LOH) on chromosome arm 9q is the most frequent gene tic alteration found in superficial and invasive transitional cell carcinom a (TCC) in a previous microsatellite-based deletion mapping study of the bl adder and upper urinary tract, indicating the presence of one or more impor tant tumor suppressor genes (TSGs). One of the putative tumor suppressor lo ci on 99 (DBCI) was mapped to 9q32-33 and the candidate region was localize d within a single YAC. We report here a case of superficial papillary TCC, which showed a homozygous deletion encompassing this candidate tumor suppre ssor region. The region of homozygous deletion spanned the interval between D9S275 and AFMA239XA9 at 9q32-33, and was estimated to be less than or equ al to 6 cM. Although homozygous deletion mapping did not narrow down the ca ndidate tumor suppressor region, this case provides further support for the presence of a TSG for TCC in this chromosomal region. To our knowledge, th is is the first report to show homozygous deletion at 9q32-33 in TCC or any other type of human tumor. Genes Chromosomes Cancer 26:171-175, 1999. (C) 1999 Wiley-Liss, Inc.