DELETION MAPPING OF CHROMOSOME-II IN CARCINOMA OF THE BLADDER

Deletions of the short arm of chromosome II have been identified by both cytogenetic and molecular criteria in bladder and other types of solid tumor, indicating the presence of one or more suppressor loci in this region. To localize the IIp deletion target(s) more precisely and to screen for loss of heterozygosity (LOH) on the long arm of the chromosome, 100 bladder tumors were analyzed for LOH on chromosome II using restriction fragment length polymorphisms (RFLPs) and microsatellite markers mapped to both IIp and IIq. Thirty-four tumors were found to have LOH at I or more loci. Of these, 17 had LOH restricted to IIp, 13 had LOH of both IIp and IIq, and 4 had LOH of IIq only. Eight tumors showed LOH at all informative loci indicating probable loss of an entire copy of chromosome II. A common region of deletion was defined on IIp between DIIS922(IIp15.5) and DIIS569 (IIp15.1-15.2). This region does not include the HRAS or WTI loci (at IIp15.5 and IIp13, respectively). Seventeen tumors had LOH on IIq, 4 of which had LOH on IIq only. The common region of deletion on IIq was between FGF3 and DIIS490 (IIq13-q23.2). Two tumors showed LOH on both IIp and IIq with a clear region of retention of heterozygosity between, indicating the existence of two deletion targets on chromosome II. (C) 1995 Wiley-Liss, Inc.