Prolactin receptor expression in the developing human prostate and in hyperplastic, dysplastic, and neoplastic lesions

In situ hybridization and immunohistochemistry were used to localize and co mpare the expression of the long form of the human prolactin receptor in fe tal, prepubertal, and adult prostate. Results were then compared with hyper plastic, dysplastic, and neoplastic lesions, Both receptor message and prot ein were predominately localized in epithelial cells of the fetal, neonatal , prepubertal, and normal adult prostate. In hyperplastic lesions the expre ssion of the receptor was unchanged with respect to normal epithelial cells . Irrespective of grade, markedly enhanced expression of the receptor was e vident in dysplastic lesions. In lower Gleason grade carcinomas the intensi ty of receptor signal at the message and protein levels approximated that f ound in normal prostatic epithelium However, In foci within higher grade ca ncers, receptor expression appeared diminished. Results from our study sugg est that prolactin action plays a role in the development and maintenance o f the human prostate and may also participate In early neoplastic transform ation of the gland. Diminution of receptor expression in high grade neoplas ms could reflect the emergence of a population of cells that are no longer responsive to the peptide hormone.