INCREASED EXPRESSION OF VASCULAR-PERMEABILITY FACTOR (VASCULAR ENDOTHELIAL GROWTH-FACTOR) AND ITS RECEPTORS IN KIDNEY AND BLADDER CARCINOMAS

Vascular permeability factor (VPF), also known as vascular endothelial growth factor, is a secreted protein implicated in tumor-associated m icrovascular hyperpermeability and angiogenesis. Tumor cells in 11 of 12 renal cell carcinomas expressed high levels of VPF messenger RNA (m RNA) by in situ hybridization, the only exception being a case of the relatively avascular papillary variant. Expression was further accentu ated adjacent to areas of necrosis. Both tumor cells and endothelial c ells in small vessels adjacent to tumor stained strongly for VPF prote in by immunohistochemistry. Endothelial cells did not express detectab le VPF mRNA, but did express high levels of mRNA for the VPF receptors flt-1 and KDR indicating that the endothelial cell staining likely re flects binding of VPF secreted by adjacent tumor cells. Three transiti onal cell carcinomas also labeled strongly for VPF mRNA. These data su ggest an important role for VPF in the vascular biology of these to co mmon human malignancies.