COEXPRESSION OF SIMPLE EPITHELIAL KERATINS AND VIMENTIN BY HUMAN MESOTHELIUM AND MESOTHELIOMA INVIVO AND IN CULTURE

  • 1 January 1984
    • journal article
    • research article
    • Vol. 44  (7) , 2991-2999
Abstract
The intermediate filament proteins present in normal and malignant mesothelium in vivo were determined. Pure sheets of normal lung mesothelium were obtained by transfer to agar-coated slides or by gentle scraping and cytocentrifugation. Cytoplasmic filament networks in the mesothelium were labeled via indirect immunofluorescence both by anti-MW 40,000 keratin and anti-vimentin antisera. Two-dimensional gel electrophoresis of the Triton:high-salt-insoluble proteins of normal lung mesothelium disclosed the presence of vimentin and all but the largest (MW 55,000) of the 4 simple epithelial keratins synthesized by mesothelial cells in culture. Samples of 3 peritoneal and 3 pleural mesotheliomas contained all 4 simple epithelial keratins or all but the MW 55,000 keratin. None of the keratins characteristic of stratified and many glandular epithelial and their malignant forms was present in these mesotheliomas. Two mesothelioma samples from which the tumor cells could be obtained free of other cell types were found to contain vimentin as well as simple epithelial keratins and to synthesize these same proteins during short-term culture. None of the mesotheliomas placed in culture grew progressively in medium optimal for the growth of normal mesothelial cells. These data demonstrate that malignant mesothelial cells preserve the normal pattern of intermediate filament protein synthesis, including coexpression of simple epithelial keratins and vimentin, and suggest the use of this characteristic as an aid in the identification of cells of mesothelial origin.