Platelet-derived growth factor: a general review with emphasis on astrocytomas

Growth factors acting in a paracrine or autocrine fashion are important in the development of normal cellular structures, and possibly in the development of neoplasia. For example, platelet-derived growth factor (PDGF) has been found in many normal tissues including the CNS, while minor changes in one of its forms (PDGF-B) converts it to the v-sis oncogene, capable of inducing sarcomas and astrocytomas in primates. PDGF is highly expressed in many human astrocytoma-derived cell lines, some of which also possess the PDGF-receptor(s), suggestive of an autocrine loop. Whether this finding is also present in the actual tumor, does it vary with tumor grade, what components of the tumor express PDGF and how does PDGF promote astrocytoma growth are some of the unanswered questions forming the basis of ongoing research efforts. This paper reviews the story of PDGF in a much oversimplified, however, hopefully understandable, fashion and presents the case of why this growth factor is of interest in understanding the biology of astrocytomas.