Coexpression of keratin- and vimentin-type intermediate filaments in human metastatic carcinoma cells.

Metastatic tumor cells of epithelial origin present in effusions from human serous cavity fluids (ascites or pleural fluid) were examined for their intermediate-sized filament types by using antibodies to keratin, vimentin, and desmin in the indirect immunofluorescence technique. Solid epithelial tumors (both primary carcinomas and their metastases) contain keratin intermediate-sized filaments exclusively. However, when these cells are present in ascitic or pleural fluid, they also express vimentin, which occurs in a fibrillar organization. The possible effects of this additional, but temporary, cytoskeleton on metastatic growth or aggressiveness (or both) are discussed.