EXPRESSION OF SURFACTANT PROTEIN-B PRECURSOR AND SURFACTANT PROTEIN-BMESSENGER-RNA IN ADENOCARCINOMA OF THE LUNG

Surfactant protein B (SP-B) is a 79-amino acid, hydrophobic protein th at plays important roles in surfactant function and homeostasis. SP-B is produced in the respiratory epithelium by proteolytic processing of a glycosylated precursor (pro-SP-B) of relative molecular mass 42,000 to 46,000. To develop diagnostic markers for pulmonary adenocarcinoma s, we examined the incidence and distribution of pro-SP-B and SP-B mRN A in paraffin sections of 35 non-small cell lung carcinomas (15 adenoc arcinomas, 15 squamous cell carcinomas, and 5 large cell carcinomas), using immunohistochemical techniques and in situ hybridization. Fiftee n nonpulmonary adenocarcinomas were used as controls. Pro-SP-B and SP- B mRNA were detected in 60% and 53% of pulmonary adenocarcinomas, resp ectively. Expression was seen in adenocarcinomas with acinar, papillar y, bronchioloalveolar, and solid growth patterns, Squamous cell and la rge cell carcinomas of the lung and nonpulmonary adenocarcinomas did n ot contain pro-SP-B immunoreactivity or SP-B mRNA. The specificity of SP-B gene expression in adenocarcinomas of the lung supports the usefu lness of pro-SP-B and SP-B mRNA in the study and diagnosis of these ne oplasms.