Platelet-derived growth factor: mechanism of action and relation to oncogenes

Recent studies of platelet-derived growth factor (PDGF) have revealed several structural and functional similarities between this growth factor or components linked to its mechanism of action and certain oncogene products: PDGF itself has a structural homology with the transforming protein of simian sarcoma virus, the PDGF receptor has a functional homology (tyrosine kinase activity) with a family of oncogene products, and PDGF induces the expression of the cellular counterparts of myc and fos. In addition, several tumour cell lines have been found to produce PDGF-like growth factors, which may cause autocrine stimulation of growth. We interpret these findings as indicating that regulatory components along the PDGF-dependent mitogenic pathway may have oncogenic properties if they are inappropriately expressed or activated.