IMMUNOREACTIVITY FOR HEPATOCYTE-GROWTH-FACTOR SCATTER-FACTOR AND ITS RECEPTOR, MET, IN HUMAN LUNG CARCINOMAS AND MALIGNANT MESOTHELIOMAS

Paraffin sections from 29 lung carcinomas (28 primary and 1 metastatic ) and 9 pleural malignant mesotheliomas were immunostained with antise ra to human hepatocyte growth factor/scatter factor (HGF/SF) and its r eceptor, met. For HGF/SF, immunoreactivity was demonstrated in all 9 m esotheliomas, 9 of 12 adenocarcinomas, and 7 of 10 squamous cell carci nomas. None of seven cases of small cell anaplastic carcinoma was posi tive. The adenocarcinomas frequently showed enhanced luminal staining, suggesting possible secretion of HGF/SF, and this pattern of staining was also seen occasionally in bronchial epithelium adjacent to the tu mour. Stromal fibroblasts also showed immunoreactivity for HGF/SF in 6 /8 cases of mesothelioma but in only 3/12 adenocarcinomas, 1/10 squamo us cell carcinomas, and 1/4 small cell anaplastic carcinomas. All tumo urs stained for met, usually strongly. The staining was mainly cytopla smic in nature, but some plasma membrane staining was usually evident. Adenocarcinomas showed strong luminal membrane staining, as did adjac ent, histologically normal bronchial epithelium. This study demonstrat es the presence of HGF/SF and met in most of the tumour types describe d, particularly mesotheliomas, and suggests that the HGF/SF/met signal ling system may play a role in the development of these tumours, eithe r by autocrine or by paracrine mechanisms.