ALTERED REGULATION OF CELL-SURFACE PEPTIDASES IN HUMAN CHOLESTEATOMA

Cholesteatoma is a destructive process involving an accumulation of de squamated keratin arising from squamous epithelium that pathologically has invaded the middle ear or mastoid process. The clinical hallmarks of cholesteatomas, namely invasion of healthy tissues, migration, unr estrained proliferation, aggressiveness, recidivism, and uncoordinated differentiation predict the existence of defects in the normal biolog y and biochemistry at the cellular constituents that compose a cholest eatoma, as well as in the cellular interactions between these cells, t he surrounding normal tissue, and the host. In the current report, we analyzed 11 cholesteatomas and matched healthy tissue for altered expr ession In four different cell surface peptidases, aminopeptidase A, am inopeptidase N, dipeptidyl peptidase IV, and neutral endopeptidase. We suggest that peptidases may modulate cell growth and differentiation by inactivating stimulatory signals (or conversely, by activating inhi bitory signals).