ALLELE LOSS AT THE RETINOBLASTOMA LOCUS IN HUMAN OVARIAN-CANCER

To gain a broad spectrum on allelic loss of specific loci in ovarian tumors, we initially examined DNA from 23 pairs of ovarian tumors and matched peripheral blood lymphocyte samples from the same patients, using 27 polymorphic DNA markers distributed on 13 chromosomes. Significant high frequency of allelic deletion (22%-44%) at chromosome 13 loci (D13S31, D13S32, D13S33, and D13S34) at bands q12-q34 was observed in tumor tissues. These results led us to investigate the loss of heterozygosity at the retinoblastoma (RB) locus in ovarian tumors, because the RB gene is a tumor-suppressor gene located at 13q14. Analysis of the variable number of tandem repeat sequence polymorphism in intron 20 in the RB gene revealed that 6 (30%) of 20 patients with informative samples showed allelic loss at the RB locus in their tumor tissues. This loss, of relatively high frequency, suggests that the RB gene, or a closely linked gene, seems to be involved in the development of ovarian cancer.