LOCALIZATION OF A TUMOR-SUPPRESSOR GENE IN 11P15.5 USING THE G401 WILMS-TUMOR ASSAY

Multiple studies have underscored the importance of loss of tumor supp ressor genes in the development of human cancer, To identify these gen es, we used somatic cell hybrids in a functional assay for tumor suppr ession in vivo. A tumor suppressor gene in 11p15.5 was detected by tra nsferring single human chromosomes into the G401 Wilms' tumor cell lin e, In order to better map this gene, we created a series of radiation- reduced t(X;11) chromosomes and characterized them at 24 loci between H-RAS and beta-globin. Interestingly three of the chromosomes were ind istinguishable as determined by genomic and cytogenetic analyses, Each contains an interstitial deletion with one breakpoint in 11p14.1 and the other breakpoint between the D11S601 and D11S648 loci in 11p15.5, PFGE analysis localized the 11p15.5 breakpoints to a 175 kb MIul fragm ent that hybridized to D11S601 and D11S648 probes. Genomic fragments f rom this 175 kb region were hybridized to DNA from mouse hybrid lines containing the Delta t(x;11) chromosomes. This analysis detected the i dentical 11p15.5 breakpoint which disrupts a 7.8 kb EcoRI fragment in all three of the Delta t(X;11) chromosomes, suggesting they are subclo nes of the same parent colony, Upon transfer into G401 cells, one of t he chromosomes suppressed tumor formation in nude mice, while the othe r two chromosomes lacked this ability. Thus, our mapping data indicate that the gene in 11p15.5 which suppresses tumor formation in G401 cel ls must lie telomeric to the D11S601 locus, Kol ef al. (Science 260: 3 61-364, 1993) have used a similar functional assay to localize a growt h suppressor gene for the RD cell line centromeric to the D11S724 locu s. The combination of functional studies by our lab and theirs signifi cantly narrows the location of the tumor suppressor gene in 11p15.5 to the similar to 500 kb region between D11S601 and D11S724.