Expression of vascular endothelial growth factor (VEGF) and platelet-derived growth factor receptor-beta (PDGFR-beta) in human gliomas

The growth of solid tumors is highly dependent on vascular proliferation. V ascular endothelial growth factor (VEGF), the main mediator of angiogenesis , and platelet-derived growth factor receptor-beta (PDGFR-beta), receptor f or the potent mitogen PDGF, are two indicators of the angiogenic potential of human gliomas. We studied a series of 57 surgical biopsies of astrocytic neoplasms by immunohistochemistry to elucidate the relationship between tu mor proliferation, quantified as Ki67-LI, and the expression of these two p roteins. Ki67-LI increases throughout histological malignancy, although staining in endothelial cells has rarely been recorded. Elevated amounts of VEGF-positi ve tumor cells (VEGF-LI) were found in anaplastic astrocytomas and glioblas tomas, mainly around areas of necrosis, cysts, or edema. Endothelium of blo od vessels was consistently stained. PDGFR-beta positivity was found in glo meruloid formations and in tumor cells, excluding pilocytic astrocytomas. M ultinucleated giant cells and perivascular tumor cells were positive in gli oblastomas. In addition, peritumoral microglia-like cells were also stained in some cases. Statistical correlation was only found between PDGFR-beta a nd Ki67 LIs. In conclusion, VEGF as permeability factor is involved in the development of secondary neoplastic changes, whereas PDGFR-beta is directly correlated to proliferation indexes. Strong expression of VEGF and PDGFR-b eta found in endothelium and tumor cells would seem to support a combined r ole in tumoral neoangiogenesis.