INTERMEDIATE FILAMENT AND CROSS-LINKED ENVELOPE EXPRESSION IN HUMAN-LUNG TUMOR-CELL LINES

  • 1 January 1985
    • journal article
    • research article
    • Vol. 45  (3) , 1187-1197
Abstract
Human lung tumor cell lines established from the major histological types of lung cancer were examined by immunofluorescent staining techniques for their patterns of intermediate filament (keratin, vimentin and neurofilament triplet protein) expression. All cell lines examined, both small cell lung carcinoma (SCLC) and on-SCLC (squamous cell carcinoma, adenocarcinoma, large cell carcinoma and mesothelioma) contained keratin, consistent with their epithelial derivation. These lung carcinoma cell lines also expressed vimentin, the characteristic intermediate filament of mesenchymal cells in vivo. In light of the proposed neuroectodermal origin of SCLC, cell lines were also studied for neurofilament expression. Two of 4 SCLC tumor cell lines, as well as non-SCLC cell lines, showed no reactivity with antibodies to neurofilament triplet protein. Two of the SCLC cell lines stained weakly with anti-neurofilament antibody. Examination of specific keratin patterns in human lung tumor cell lines by selective immunoprecipitation with keratin antiserum and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that small-sized keratin proteins (MW 44,000-52,000) were present in cell lines derived from SCLC and non-SCLC types of lung cancer. Tumor cell lines exhibiting squamous differentiation by light microscopic criteria (i.e., intracellular keratin, intercellular bridging, pearl formation and/or individual cell keratinization) also displayed a preponderance of intermediate sized keratins (MW 57,000 and 59,000) and exhibited another feature of terminal keratinocyte differentiation (cross-linked envelope formation). Mesothelioma cell lines had varying keratin profiles. The presence of keratin proteins in all SCLC cell lines examined argues against a neuroectodermal origin for these tumors and is consistent with the notion that these tumors arise from a common bronchial stem cell, similar to that from which other types of bronchogenic carcinomas arise.