Relationship between cellular retinoic acid-binding protein and histology of human lung tumors.

Human lung tumors from 28 patients were investigated by sucrose density analysis for the presence of cellular retinoic acid-binding proteins. In the tumor-free lung tissue and in most of the 20 squamous cell carcinoma and in 1 small cell carcinoma specimens tested no specific binding of retinoic acid was detectable, whereas these binding proteins were observed in 5 adeno- and 1 large cell carcinoma. The amount of retinoic acid-binding protein was slightly increased in 1 bronchial adenoma considered to be a semimalignant tumor. These findings suggest that the occurrence of retinoic acid-binding proteins within lung carcinomas may be related to the histological type of lung cancer. Thus, the antineoplastic effects of retinoic acid suspected to be mediated by specific binding proteins are not generally to be expected on lung cancer.