LOSS OF HETEROZYGOSITY ON THE SHORT ARM OF CHROMOSOME-8 IN MALE BREAST CARCINOMAS

Identification of Loss of heterozygosity (LOH) at specific genetic loc i in neoplastic cells suggests the presence of a tumor suppressor gene within the deleted region. LOH on chromosome 8p has been identified i n colorectal, bladder, hepatocellular, and prostatic carcinomas. Littl e is currently known about the molecular events occurring during the d evelopment of male breast cancer. We studied LOB on chromosome 8p in 2 3 male breast carcinomas. Five polymorphic DNA markers were used: D8S1 36 and D8S137 on 8p12-21.3; and D8S254, D8S258, and D8S349 on 8p22. DN A was extracted from microdissected normal and tumor cells obtained fr om 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 wa s not Lost in these tumors. Our results show that there are two discre te areas of deletion on chromosome 8p in male breast cancer, suggestin g the presence of one or more tumor suppressor genes that may play a r ole in the development or progression of the disease.