Expression of brx proto-oncogene in normal ovary and in epithelial ovarian neoplasms

OBJECTIVE: We previously identified a protein, Err, that interacted with estrogen receptor or. Sequence analysis determined that Err is a novel member of the Dbl family of oncoproteins involved in signaling pathways that regulate cell growth. Because the Err protein was found to be highly expressed in hormone-responsive breast epithelium, the objective of this study was to determine whether Err was expressed in both normal and neoplastic ovarian tissues; STUDY DESIGN: A polyclonal antiserum directed against the Err protein was used to perform immunolocalization on sections from 5 normal ovaries and 20 ovarian neoplasms. Chromosomal localization of the brx gene was accomplished by means of fluorescence in situ hybridization. Northern and Western blot analyses were performed on extracts prepared from human ovaries. RESULTS: Err protein was localized to the cytoplasm of granulosa cells from mature graafian follicles, the corpus luteum, and islands of hi[ar cells in normal ovaries. In tumors with low malignant potential and ovarian carcinomas the neoplastic epithelium stained strongly for Err protein; Northern and Western blot analyses, respectively, confirmed expression of Err messenger ribonucleic acid and protein in normal ovary. Finally, the brx gene was localized to 15q25. CONCLUSION: The proto-oncogene brx is expressed in specific normal human ovarian tissues and is also present in ovarian epithelial neoplasms.