PROTEIN PHOSPHATASE-2A ASSOCIATION WITH MICROTUBULES AND ITS ROLE IN RESTRICTING THE INVASIVENESS OF HUMAN HEAD AND NECK SQUAMOUS-CELL CARCINOMA-CELLS

The role of protein phosphatase-2A (PP-2A) in regulating the motility and adhesion of human head and neck squamous cell carcinomas (HNSCC) w as investigated. Immunofluorescent staining of these HNSCC cells showe d PP-2A can co-localize with microtubules. That the PP-2A influences m otility was shown by the increase in HNSCC cell migration through lami nin and vitronectin when PP-2A was selectively inhibited with low dose okadaic acid, and by the reduction in invasion through these same mat rix components by elevators of PP-2A activity. Motility of HNSCC cells through collagen I or fibronectin was not modulated by PP-2A, The red uction in HNSCC migration through vitronectin or laminin that resulted from treatment with PP-2A elevators was associated with an increase i n cellular adhesiveness to these same ECM components. These studies sh ow the association of PP-2A with the cellular cytoskeleton and its rol e in restricting the invasiveness of tumor cells through select extrac ellular matrix components. (C) 1997 Elsevier Science Ireland Ltd.