Loss of heterozygosity on the short arm of chromosome 8 in male breast carcinomas.

Identification of loss of heterozygosity (LOH) at specific genetic loci in neoplastic cells suggests the presence of a tumor suppressor gene within the deleted region. LOH on chromosome 8p has been identified in colorectal, bladder, hepatocellular, and prostatic carcinomas. Little is currently known about the molecular events occurring during the development of male breast cancer. We studied LOH on chromosome 8p in 23 male breast carcinomas. Five polymorphic DNA markers were used: D8S136 and D8S137 on 8p12-21.3; and D8S254, D8S258, and D8S349 on 8p22. DNA was extracted from microdissected normal and tumor cells obtained from formalin-fixed, paraffin-embedded tissue sections and amplified by the PCR. LOH was identified in 19 of 23 cases (83%) with at least one marker. Seven cases showed LOH only at 8p22, six cases showed LOH only at 8p12-21.3, and six cases showed LOH at both 8p22 and 8p12-21.3. In five of these last six cases, at least one locus was retained between the two deleted regions; thus, the whole short arm of chromosome 8 was not lost in these tumors. Our results show that there are two discrete areas of deletion on chromosome 8p in male breast cancer, suggesting the presence of one or more tumor suppressor genes that may play a role in the development or progression of the disease.