Cytoskeleton-associated proteins: their role as cellular integrators in the neoplastic process

The cytoskeleton (CSK) appears to have a role in determining cell shape, cell motility, anchorage-dependentgrowth, distribution of cell surface proteins, and the localization of organelles such as mitochondria and polyribosomes. Many of the proteins that compose the major CSK filaments have been characterized. Among these proteins are actin in microfilaments, tubulin in microtubules, and the heterogeneous group of intermediate filament proteins that are associated with different cell types (keratin in epithelial cells, vimentin in fibroblasts, desmin in muscle cells, glial filament protein in glial cells, and the neurofilament protein subunits in neural tissue). Recently, many other proteins have been described to be components of the cytoskeleton. The expression of these different CSK proteins in tumor cells reflects their morphologic and functional differentiation. The pattern and organization of CSK components in tumor cells seem to correlate with cell adhesion, spreading and locomotion in vitro, and possibly tumor invasiveness and metastatic capacity in vivo. Further characterization of CSK composition and architecture may provide important information about the lineage characteristics and biologic behavior of tumor cells.