Nonneoplastic Human Kidney Tissue Growth Factor Receptor Messenger RNA in Neoplastic and and Epidermal α Expression of Transforming Growth Factor

Using Northern blot analysis, we have demonstrated that mRNA for transforming growth factor a (TGF-a) was expressed in five malignant kidney tissue specimens but was not detected in their autologous nonneoplastic homologues. In addition, the expression of epidermal growth factor (EGF) receptor mRNA in these malignant tissues was 2to 3-fold greater than in nontransformed tissues. In two cases examined using immunohistochemistry, we were able to correlate the increased expres sion of the mRNA with an increase in protein expression. Since TGF-a is known to bind to the EGF receptor, the finding of an increased expression of both TGF-a and EGF receptor mRNA in kidney tumor tissue suggests that interaction between TGF-a and the EGF receptor may play a role in promoting transformation and/or proliferation of kidney neoplasms, perhaps by an autocrine mechanism.