MESSENGER-RIBONUCLEIC-ACID EXPRESSION OF PLATELET-DERIVED GROWTH-FACTOR SUBUNITS AND RECEPTORS IN PITUITARY-ADENOMAS

Little is known about the expression of growth factors and their recep tors in pituitary tumors or the relationship of growth factors to pitu itary neoplasia. Platelet-derived growth factor (PDGF) is a potent mit ogen that has been postulated to stimulate tumor growth through autocr ine and/or paracrine loops in a number of human tumors. In the present study we demonstrate messenger ribonucleic acid expression of the PDG F subunits and receptors in a variety of human pituitary adenomas and in a normal human anterior pituitary gland. Northern blot analysis per formed on 34 pituitary adenomas showed that all tumors expressed the P DGF-A and PDGF-B subunits, the majority (94%) expressed the PDGF-beta receptor, and a subset (44%) expressed the PDGF-alpha receptor. The no rmal anterior pituitary studied expressed all of the PDGF subunits and receptor subunits. Clinically, there was no correlation between expre ssion of the PDGF subunits or receptors and tumor size or with invasio n into adjacent structures (cavernous sinus, sphenoid sinus, or clivus ). A higher proportion of the endocrinologically active adenomas expre ssed the PDGF-alpha receptor (5 of 8) compared to the endocrine inacti ve tumors (10 of 26). The function of PDGF in the pituitary is current ly not known. The finding that PDGF subunit and receptor messenger rib onucleic acids are coexpressed in pituitary adenomas and normal anteri or pituitary suggests that autocrine and/or paracrine loops involving PDGF may exist in pituitary adenomas and normal anterior pituitary.