Analysis of expression of erythropoietin-binding sites in human lung carcinoma by the biotinylated ligand.

Recombinant glycosylated erythropoietin (EPO) was biotinylated with biotin-aminocaproyl hydrazide via periodate-treated sialic acid moieties and applied to sections of 64 tumors of the lower respiratory tract, comprising 19 primary adenocarcinomas, 19 epidermoid carcinomas, 13 large cell anaplastic carcinomas, 11 small cell lung carcinomas, 11 intrapulmonary metastases, 1 mesothelioma and 1 lymphocytic interstitial pneumonia. The formalin-fixed, paraffin-embedded specimens were incubated with labelled EPO at room temperature and a concentration of 10 micrograms/ml for 60 min. The expression of the EPO-binding sites was visualized by the ABC technique. All of the analyzed large cell anaplastic carcinomas and the majority of the epidermoid carcinoma (89%), adenocarcinoma (79%), and metastases (82%) displayed binding capacities for EPO. Five out of the eleven small cell lung carcinomas, the analyzed mesothelioma and lymphocytic interstitial pneumonia revealed definite staining, too. Binding sites could, in addition, be seen in air dried, non-fixed, acetone-fixed, and ether-ethanol-fixed cytological specimens. The data indicate that the expression of binding sites with specificity for EPO can be frequently seen in human bronchial malignancies.