Frequent loss of heterozygosity on chromosomes 6q, 11, and 17 in human ovarian carcinomas.

Recently, tumor-specific allele loss has been shown to be an important characteristic of some tumors. When such loss includes one or more growth-regulatory genes, it may allow the expression of tumorigenicity. Using Southern blots, we analyzed normal and tumor DNA samples from 19 ovarian cancer patients, using a series of polymorphic DNA probes that map to a variety of chromosomal loci. Of 14 informative cases, tumor-specific allelic loss was observed in nine (64%) at the estrogen receptor (ESR) gene locus on chromosome 6q. On chromosome 17p at the D17S28 and D17S30 loci, allelic losses were also detected in 6 of 8 (75%) and 9 of 14 (64%) cases, respectively. Allelic loss at the HRAS1 gene locus on chromosome 11p occurred in 5 of 11 (46%) informative cases. The relatively high incidence of these allelic losses observed on chromosome 6q represents the first implication by molecular genetic analysis of this chromosomal region in a human malignancy, and it thus appears to be a genetic change specific to ovarian carcinoma. DNA sequence losses on 11p and 17p, also reported for other cancers, may reflect the presence of tumor- or growth-suppressor genes on these chromosomes that are important in the genesis of many tumor types, including ovarian malignancies.