TRANSFORMING GROWTH-FACTOR-ALPHA EXPRESSION IN HUMAN RENAL-CELL CARCINOMA - TGF-ALPHA EXPRESSION IN RENAL-CELL CARCINOMA

Objectives. To characterize the expression of transforming growth fact or-alpha (TGF-alpha) in various histologic types of renal cell carcino mas. Methods. Immunohistochemistry of renal cell carcinoma and adjacen t normal tissue was performed on formalin-fixed tissue using a specifi c monoclonal antibody to TGF-alpha. Results. Clear and distinct staini ng was present in normal distal convoluted tubules and collecting duct s. The growth factor was not observed in the glomerulus or the proxima l tubule. In tumors composed of clear cells, staining was evident only in endothelial cells but not in the tumor cells themselves. In granul ar cell type tumors, the tumor cells as well as endothelial cells stai ned for TGF-alpha. When mixed cell type tumors were studied, a heterog enous pattern of growth factor expression was found. Endothelial cells and granular cells but not clear cells demonstrated positive staining . Conclusions. These studies suggest that TGF-alpha is likely to play a major role in neovascularization of clear cell carcinomas and that t he growth factor may be more important in supporting proliferation of granular cell type tumors.