Cell of Origin of Malignant Mesothelioma dictates the tumor subtype

Malignant Mesothelioma (MM) is one of the most lethal human malignancies of the thoracic cavity. We have determined the cell of origin of these tumors by inactivating Nf2 and Trp53 in Cdkn2a-deficient mesothelial cells both in vitro and in vivo. Cloned, in vitro switched cell lines showed distinct protein marker profiles that upon grafting in recipient mice, gave rise to epithelial, sarcomatoid or biphasic MM. We show that corresponding cell types are present in the mesothelial lining, each capable to serve as a cell of origin of one of the distinct MM subtypes of which the RNA expression profile aligns with corresponding human samples. Therefore, the specific target cell is a critical factor in dictating the tumor subtype of MM. Human mesothelioma cells grown in immune deficiemt mouse