Coexpression of TGF alpha, epidermal growth factor receptor, and P-glycoprotein in normal and benign diseased breast...

Twenty-four normal or benign breast tissues were examined for the expression of transforming growth factor-alpha (TGF alpha), epidermal growth factor receptor (EGFR), and P-glycoprotein, the product of the mdr-1 gene. Specific staining for all three proteins was observed in the majority of the samples. P-glycoprotein staining was present in most (88%), and confined to the lumenal surface of the ductal epithelium. Membranous EGFR expression was observed in epithelial cells in 92% of the specimens and 42% displayed both myoepithelial and epithelial cell staining. TGF alpha staining was intense and uniformly distributed through the cytoplasm (96%). Coexpression of EGFR, TGF alpha, and P-glycoprotein in normal human breast tissues suggests a role for each of those proteins in normal breast physiology. An interaction may be present in normal breast tissue between the EGF receptor pathway and P-glycoprotein.