Expression of platelet-derived growth factor and transforming growth factor and their correlation with cellular morphology in glial tumors.

This study was undertaken to evaluate the role of two sets of growth factors, platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta), in the induction and maintenance of glial tumors and their phenotypic expression. Explants from eight malignant tumors, five benign tumors, and two nontumor glial cells were analyzed for levels of messenger ribonucleic acid (mRNA) expression of PDGFA, PDGFB, TGF-beta 1, and TGF-beta 2. Results were normalized to the mRNA expression of tubulin, a "housekeeping" gene present in glial cells. Of the 15 explants tested, PDGFB was seen in six, all of which were malignant tumors; PDGFA was seen in all 15 with much higher levels expressed in malignant tumors; and TGF-beta 1 and TGF-beta 2 were seen in all 15 without a clear difference between cell types, although expression tended to be higher in malignant tumors. This project supports the theory that the induction and maintenance of glial tumors is likely to be a multifactorial phenomenon.