HUMAN PROSTATE ADENOCARCINOMAS EXPRESS IN-VIVO MESSENGER-RNAS AND PROTEIN PRODUCTS FOR PLATELET-DERIVED GROWTH FACTOR-B AND ITS RECEPTOR

In situ hybridization and immunocytochemistry studies have shown the i n vivo expression of platelet-derived growth factor B (PDGF-B) and PDG F receptor (PDGF-R) beta mRNAs and their respective protein products i n the malignant epithelial cells of eight primary human prostatic aden ocarcinomas. Examination of five nonmalignant adjacent prostate tissue s did not demonstrate significant expression of PDGF B and PDGF-R beta mRNAs or production of their respective protein products in nonmalign ant epithelial cells. Expression of androgen receptor mRNA was shown t o be present in the epithelial cells of all of the five nonmalignant a djacent prostate tissues. There was a significant reduction in the exp ression of androgen receptor mRNA in poorly differentiated regions, an d a moderate reduction in the well differentiated regions of the malig nant tissues. It appears that dedifferentiation of the tumor cells in prostatic adenocarcinomas is accompanied by a reduction in androgen re ceptor mRNA expression. The coexpression of PDGF and its receptor in t he malignant epithelial cells of prostatic adenocarcinomas signifies a n abnormal autocrine loop that may contribute to their growth and main tenance.