Differential expression of intermediate filament proteins distinguishes classic from variant small-cell lung cancer cell lines.

The expression of intermediate filament proteins in classic and variant-type small-cell lung carcinoma (SCLC) cell lines was studied using immunocytochemical techniques, two-dimensional gel electrophoresis and immunoblotting assays. Classic SCLC cell lines contain cytokeratin proteins but no neurofilaments. In contrast, variant cell lines do not contain detectable amounts of cytokeratins but partly express neurofilaments and vimentin. These results explain apparent discrepancies on the intermediate filament content of SCLC described in the recent literature. The application of antibodies to fresh biopsy specimens of SCLC may in the future allow the identification of the variant type of cells in clinical SCLC specimens and may have a major impact on therapeutic strategy and prognosis in these patients.