COEXPRESSION OF TGF-ALPHA, EPIDERMAL GROWTH-FACTOR RECEPTOR, AND P-GLYCOPROTEIN IN NORMAL AND BENIGN DISEASED BREAST TISSUES

Twenty-four normal or benign breast tissues were examined for the expr ession of transforming growth factor-alpha (TGF alpha), epidermal grow th factor receptor (EGFR), and P-glycoprotein, the product of the mdr- 1 gene. Specific staining for all three proteins was observed in the m ajority of the samples. P-glycoprotein staining was present in most (8 8%), and confined to the lumenal surface of the ductal epithelium. Mem branous EGFR expression was observed in epithelial cells in 92% of the specimens and 42% displayed both myoepithelial and epithelial cell st aining. TGF alpha staining was intense and uniformly distributed throu gh the cytoplasm (96%). Coexpression of EGFR, TGF alpha, and P-glycopr otein in normal human breast tissues suggests a role for each of those proteins in normal breast physiology. An interaction may be present i n normal breast tissue between the EGF receptor pathway and P-glycopro tein.