Phenotypic characteristics of mouse lung adenoma induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone

The expression profile of adenoma induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in A/J mice was compared with that of normal lung tissue by suppression subtractive hybridization (SSH). The mRNAs of surfactant-associated protein A (SP-A) and lysozyme showed characteristically higher transcription in the adenoma tissue than in normal lung. High expression of both SP-A and lysozyme in tumor cells was confirmed by in situ hybridization (ISH). In normal lung, alveolar type II pneumocytes were positive for both SP-A and lysozyme, indicating that tumor cells retained the phenotypic characteristics of the murine alveolar type II pneumocytes. Previous studies of human adenocarcinomas have shown that the two proteins are expressed reciprocally; SP-A and lysozyme are differential markers of atypical adenomatous hyperplasia (AAH) and non-goblet cell type adenocarcinoma, and of goblet cell type adenocarcinoma, respectively. Thus, the present results indicate that the phenotype of NNK-induced A/J mouse adenoma differs from that of AAH, which is thought to be a preinvasive lesion of human adenocarcinoma.