EXPRESSION OF TRANSFORMING GROWTH-FACTOR-ALPHA AND EPIDERMAL GROWTH-FACTOR RECEPTOR IN MIDDLE-EAR CHOLESTEATOMA

To study the possible autocrine growth stimulation of cholesteatoma ep ithelium, the expression of transforming growth factor alpha (TGF-alph a) and epidermal growth factor receptor (EGFR) in middle ear cholestea toma was investigated by immunohistochemical staining techniques. Twen ty cholesteatoma samples obtained at operation and six normal skin spe cimens collected from the external ear canal were used in the study. I mmunostaining for TGF-alpha showed a diffuse cytoplasmic staining patt ern. It was weakly expressed in the basal layer of the normal epiderma l epithelium but was more strongly expressed in all cholesteatoma spec imens. EGFR showed a dot-like/diffuse cytoplasmic and cell membrane st aining pattern. EGFR-positive cells were seen in the basal layer of no rmal epidermis. In the cholesteatoma specimens, expression of EGFR was not only confined to the basal layer but persisted into the upper lay ers of the epithelium. Our findings indicate that an autocrine growth stimulation by TGF-alpha and EGFR may contribute to the unrestrained g rowth of cholesteatoma epithelium in the middle ear cavity.