Establishment of a human malignant fibrous mesothelioma cell line and the biological characteristics compared with malignant epithelial mesothelioma cell line.

Two human malignant mesothelioma cell lines, which we designated "epithelial mesothelioma cells" and "fibrous mesothelioma cells", were established from the pleural fluid containing malignant mesothelial cells of a 72-year-old Japanese man. These cell lines were separated by the colonial techniques from the initiation of the primary cultures and grew well without interruption for 12 years. They were characterized as producing hyaluronic acid. These cell lines displayed different biological characteristics, including morphology, heterotransplantability and genetics using with BAC array CGH. The epithelial mesothelioma cells were epithelial in shape and transplantable into the subcutis of nude mice, while the cells of the fibrous mesothelioma line were fibroblast-like and transplantable into the submucosa of Hamster's cheek pouches but not into the subcutis of nude mice. The mesotheliomas are classified into three types: epithelial mesothelioma, fibrous mesothelioma and mixed type. The gene copy number losses observed on 9p21.3, 9p21.2, 9p21.1, among others may be a major mechanism of malignant mesothelioma carcinogenesis. We considered and supported the combination theory for the histogenesis of malignant mesothelioma.