HUMAN-CHROMOSOME-7 CARRIES A PUTATIVE TUMOR-SUPPRESSOR GENE(S) INVOLVED IN CHORIOCARCINOMA

Choriocarcinoma developed from a complete hydatidiform mole has an uni que genetic feature that involves monoallelic contribution from the pa ternal genome, To the chromosome carrying putative tumor gene(s), micr ocell-hybrids were isolated following fusion of choriocarcinoma cells with microcells from mouse A9 cells containing a single human chromoso me (1, 2, 6, 7, 9 or 11), Microcell-hybrids with the introduction of c hromosome 7 were suppressed or modulated for tumorigenicity and exhibi ted altered in vitro growth properties, Introduction of chromosomes 1, 2, 6, 9 or 11 had no effect, Tumorigenic revertants isolated from mic rocell-hybrids with the introduced chromosome 7 contains reduced numbe rs of chromosome 7, These findings suggest that chromosome 7 contains a putative tumor suppressor gene(s) for choriocarcinoma, Alterations i n tumorigenic phenotypes seen in microcell-hybrids were not associated with the presence of either ERV3 or H-plk locus located on the introd uced chromosome 7, indicating the putative tumor suppressor gene(s) is outside of ERV3 and H-plk gene loci, Furthermore, we obtained evidenc e to define a critical region on chromosome 7 (7p12-7q11.23) that was frequently lost in surgically removed choriocarcinoma tissues and cell lines, Using a panel of microsatellite markers, biallelic deletions w ere observed, which strongly suggests the presence of a tumor suppress or gene(s) within this critical region.