The role of fascin in the migration and invasiveness of malignant glioma cells.

Malignant glioma is the most common primary brain tumor, and its ability to invade the surrounding brain parenchyma is a leading cause of tumor recurrence and treatment failure. Whereas the molecular mechanisms of glioma invasion are incompletely understood, there is growing evidence that cytoskeletal-matrix interactions contribute to this process. Fascin, an actin-bundling protein, induces parallel actin bundles in cell protrusions and increases cell motility in multiple human malignancies. The role of fascin in glioma invasion remains unclear. We demonstrate that fascin is expressed in a panel of human malignant glioma cell lines, and downregulation of fascin expression in glioma cell lines by small interfering RNA (siRNA) is associated with decreased cellular attachment to extracellular matrix (ECM) and reduced migration. Using immunofluorescence analysis, we show that fascin depletion results in a reduced number of filopodia as well as altered glioma cell shape. In vitro invasiveness of U251, U87, and SNB19 glioma cells was inhibited by fascin siRNA treatment by 52.2%, 40.3%, and 23.8% respectively. Finally, we show a decreased invasiveness of U251-GFP cells by fascin knockdown in an ex vivo rat brain slice model system. This is the first study to demonstrate a role for fascin in glioma cell morphology, motility, and invasiveness.