Presence of cellular retinol and retinoic acid-binding proteins in epidermoid carcinoma of the oral cavity and oropharynx.

Epidermoid carcinomas of the oral cavity and oropharynx from six patients were examined for the presence and amount of cellular retinol (CRBP) and cellular retinoic acid-binding (CRABP) proteins. In all cases adjacent, grossly normal tissue was similarly examined. For each example CRBP levels were significantly higher in tumor tissue compared to adjacent tissue. In four cases CRABP was significantly higher. This is of interest because retinol, retinoic acid and their analogs have been shown to inhibit the development of various epithelial tumors, and this inhibition is possibly mediated by these binding proteins.