ALLELIC 3P DELETIONS IN HIGH-GRADE CARCINOMAS AFTER TRANSFORMATION INVITRO OF HUMAN UROEPITHELIAL CELLS

Restriction fragment length polymorphism (RFLP) analysis for allelic losses on the chromosome arm 3p were performed on independent carcinomas produced in athymic nude mice after transformation in vitro of a pseudodiploid clonal SV40-immortalized human uroepithelial cell line (SV-HUC). We analyzed ten primary carcinomas with heterogeneous phenotypes for deletions on 3p by using three informative probes, D3S30, D3S2, and D3F15S2, which map to the 3p11-p14, 3p21.1, and 3p21 regions, respectively. Five of the ten primary cancers showed reduction to homozygosity with at least one of the probes, and all five cancers were high-grade and poorly differentiated. We also analyzed six carcinomas that arose after progression of low-grade cancers, either spontaneously or after exposure to a human bladder carcinogen, to higher grades (progressed carcinomas). Four of the six exhibited 3p allelic loss. No preferential loss of a specific 3p allele was observed in any of the carcinomas. In addition, whereas most of the carcinomas showed allelic loss for all three of the probes, indicating a large-scale deletion, several of the carcinomas exhibited losses for only one or two of the probes, thus making it possible, along with the cytogenetic data, to define the least common region of deletion to 3p13 --> p14.2. These results support the hypothesis that nonrandom loss of a gene or genes on 3p leads to the development of cancer. Furthermore, these findings associate deletion of a putative 3p13 --> p14.2 tumor suppressor gene region with the development of high-grade uroepithelial carcinomas.