IMMUNOHISTOCHEMISTRY OF CYCLIN D1 IN HUMAN BREAST-CANCER

Cyclin D1/PRAD 1, a cell cycle-related gene mapped to chromosome 11q13 , has been found to be amplified in some breast cancers and squamous c ell carcinomas of the head and neck, and esophagus. In this study, ove rexpression of cyclin D1/PRAD1 gene was demonstrated immunohistochemic ally in 35 of 43 (81.3%) cases of human breast cancer, with a newly av ailable anticyclin D antibody. Neither normal epithelial components no r glandular structures from samples of fibrocystic disease, were react ive. Amplification of the gene was detected in 4 of 23 (17%) cases by Southern analysis. Increased gene dosage does not seem to be the only mechanism that resulted in increased protein expression as detected by immunohistochemistry. Because the less differentiated high grade tumo rs exhibited a more intense nuclear stain and non-neoplastic epithelia l components were not stained, the use of cyclin D1/PRAD1 has potentia l as a tumor marker.