Vascular endothelial growth factor (VEGF) expression in human pituitary adenomas and carcinomas

Vascular endothelial growth factor (VEGF) is a key mediator of endothelial cell proliferation, angiogenesis, and vascular permeability. Little is know n about its expression in human pituitary adenomas. We examined 148 human pituitary adenomas for VEGF protein expression by imm unohistochemistry. The strongest immunoreactivity was present in GH adenoma s, corticotroph, silent corticotroph, silent subtype 3, and nononcocytic nu ll cell adenomas. GH adenomas treated with octreotide stained less intensel y than did untreated tumors. Relatively weak staining was present in PRL, g onadotroph, thyrotroph, and oncocytic null cell adenomas in the same sectio ns showed evidence of down-regulation of VEGF protein expression in adenoma s. Pituitary carcinomas usually had stronger staining than adenomas. In situ hybridization studies with oligonucleotide probes showed positive s taining in all groups with stronger staining in GH, ACTH, TSH, and gonadotr oph adenomas and in pituitary carcinomas, These results indicate that VEGF expression is more prominent in certain ad enoma subtypes, that decreased expression occurs in adenomas as compared to nontumorous pituitary and that carcinomas show increased VEGF expression r elative to adenomas suggesting up-regulation of VEGF during pituitary tumor progression.