FLUORESCENCE IN-SITU HYBRIDIZATION DELETION MAPPING AT 4P16.3 IN BLADDER-CANCER CELL-LINES REFINES THE LOCALIZATION OF THE CRITICAL INTERVAL TO 30 KB

An allelotype analysis of transitional cell carcinoma of the bladder i dentified loss of heterozygosity (LOH) on chromosome arm 4p in 22% of tumours. in a more detailed LOH study of 178 bladder carcinomas, a 750 kb common region of deletion was identified between the markers D4S43 and D4S127 just telomeric to the Huntington disease locus. To refine this region of deletion at 4p16.3, we have carried out detailed fluore scence in site hybridisation (FISH) analysis of 12 bladder cancer cell lines by using a chromosome 4 centromeric probe combined with a serie s of cosmid probes from contigs spanning the 750 kb region of deletion . A common 30 kb region of deletion was identified at 4p16.3 in over o ne-third of the bladder cancer cell lines analysed. The present study has refined the localisation of the critical region of deletion from 7 50 kb to approximately 30 kb, providing a precise starting point for p ositional cloning of the gene(s) involved in bladder cancer from withi n a very gene-rich region on chromosome band 4p16.3. This study demons trates that FISH can be used for fine deletion mapping of potential tu mour suppressor gene regions. The utilisation of FISH analysis to map chromosomal deletions should facilitate positional cloning of other ge nes as bacterial artificial chromosome (BAC) and yeast artificial chro mosome (YAC) contigs of the human genome are established. (C) 1996 Wil ey-Liss, Inc.