Coexpression of intermediate filaments in squamous cell carcinomas of upper aerodigestive tract before and after radiation and chemotherapy

Frozen sections of 48 squamous cell carcinomas and seven undifferentiated carcinomas of the upper aerodigestive tract were investigated immunohistochemically with monoclonal antibodies specific for keratin, vimentin, desmin, neurofilaments, and glial fibrillary acidic proteins. In nine squamous cell carcinomas (19%) and six undifferentiated carcinomas (86%) obtained before treatment coexpression of keratin and vimentin was detected in some tumor cells by double immunofluorescence studies. Nine squamous cell carcinomas expressed neurofilaments in scattered tumor cells. Coexpression of vimentin or neurofilaments was seen especially in the peripheral cell layer of the tumor nests and did not seem to correlate with the degree of differentiation. Three undifferentiated carcinomas additionally expressed desmin, and one tumor contained neurofilaments. Glial fibrillary acidic proteins were not detected. Increased coexpression of keratin with vimentin, desmin, or neurofilaments was seen in some tumors that were studied before and after radiation/chemotherapy, suggesting that the intermediate filament profile of tumor cells can be altered by external influences.