Oncogenes and growth factors in gliomas.

The activation of cellular proto-oncogenes is related to the genesis and progression of neoplasias. Protein growth factors and their cellular receptors have been identified as products of some proto-oncogenes. The role of epidermal growth factor receptor (EGFr) in gliomas is presented. The expression of mRNA for platelet-derived growth factor (PDGF) and PDGF B-type receptor (PDGF-rec-B) in gliomas is analyzed. Gliomas express "in vivo" PDGF.B and PDGF-rec-B mRNAs. PDGF.B mRNA levels correlate with GFAP mRNA and does not correlate with the degree of malignancy. This is in agreement with the hypothesis of an autocrine growth stimulation in gliomas. However some findings seem to indicate that in these tumors the PDGF-rec-B is preferentially expressed by vascular elements. Thus, also a paracrine loop for endothelial cell growth stimulation may be suggested in malignant gliomas.