EXPRESSION OF TRANSFORMING GROWTH-FACTOR-ALPHA (TGF-ALPHA) IN CHOLESTEATOMA

This study aims at elucidating the role of cytokines in the mechanism of proliferation of cholesteatoma epithelium by investigating the mode of expression of epidermal growth factors, such as TGF-alpha. The sub jects of this study were patients who had undergone operation for midd le ear cholesteatoma. Skins of the bone region of the external ear can al (normal skin) of the same patients were used as the negative contro l. The mode of expression of TGF-alpha was studied by immunohistochemi stry and in situ hybridization. In the immunohistochemical study, ther e were no conspicuous differences observed between cholesteatoma tissu es and normal skin. After in situ hybridization, expression of TGF-alp ha mRNA was mainly observed in the epidermal basal cell layer in the n ormal skin, while in the cholesteatoma epidermis with severe inflammat ory cell infiltration, expression of TFG-alpha mRNA was observed up to layers superior to the basal cell layer. The expression of TGF-alpha mRNA is greatly affected by subepithelial connective tissue, strongly suggesting involvement of paracrine regulation in proliferation of cho lesteatoma epithelium.