LOCALIZATION OF BRCA1 GENE-EXPRESSION IN ADULT CYNOMOLGUS MONKEY TISSUES

The breast and ovarian cancer susceptibility gene BRCA1 encodes a phos phoprotein of 1863 amino acids containing a highly conserved N-termina l RING finger domain and a C-terminal acidic region typical of several transcription factors. BRCA1 acts as a tumor suppressor that may inhi bit the proliferation of breast and ovarian cancer cells. To gain know ledge and to further understand the biological function of BRCA1, we e xamined its localization and expression in various tissues from 20-yea r-old male and female cynomolgus monkeys (Macaca fascicularis) by in s itu hybridization using a S-35-labeled human BRCA1 DNA probe fragment derived from exon 11. In mammary glands, BRCA1 expression was primaril y located in the duct and acinar epithelial cells. In the ovary, stron g BRCA1 expression was detected in granulosa cells in maturing follicl es and in luteal cells of the corpus luteum, as well as in the epithel ial cells overlying the tunica albuginea. Specific signal was also obs erved in epithelial cells of the oviduct, endometrium, cervix, and vag ina. Moreover, BRCA1 was strongly expressed in the germinal epithelium of the seminiferous tubules as well as over interstitial cells of the testis, in the epithelium of the epididymis, and in epithelial cells bordering the glandular lumen of the seminal vesicles. Signal was also detected in both the anterior and posterior lobes of the pituitary. I n the adrenal glands, the signal was greater in the zona glomerulosa c ompared to the two other cortical zones, whereas the medullary cells w ere weakly labeled. In the stomach, and in small and large intestine, epithelial cells of the crypts usually exhibited stronger positive rea ction than that observed over surface epithelial lining cells. BRCA1 e xpression was also found in diverse types of epithelial cells of the t hyroid, pancreas, salivary glands, trachea, urinary bladder, and kidne ys. In addition to demonstrating widespread tissue-and cell-specific e xpression of the BRCA1 gene in primate tissues, primarily in the epith elia, we observed a weaker but specific signal in various other cell t ypes, suggesting a generalized biological function of BRCA1.