Loss of heterozygosity at 11q22-q23 in breast cancer.

Studies of loss of heterozygosity (LOH) in breast tumor DNA suggest that several tumor suppressor genes participate in the pathogenesis of breast cancer. Although the short arm of chromosome 11 has been implicated in breast cancer development, no previous LOH studies have indicated the involvement of a suppressor gene on 11q in breast carcinoma. To this end, tumor samples and corresponding normal tissue were collected from 62 unselected patients with primary breast cancer, and the extracted DNA was analyzed by polymerase chain reaction using microsatellite markers on chromosome 11. We found that 39% of the tumors (22 of 57 informative cases) revealed allelic loss in the region 11q22-23, and this loss was independent of LOH found to occur on 11p15. Interestingly, more than 90% of the tumors showed concordant loss of alleles at both 11q and 17p. The marker D11S528, showing LOH in 39% of informative cases, had the highest frequency of LOH among the markers that were used. The data presented indicate that the common overlapping region of LOH is between the loci D11S35 and D11S29, suggesting that this area contains a tumor suppressor gene frequently lost in breast cancer.