CD44 is involved in migration but not spreading of astrocytoma cells in vitro

Local tumour-cell invasiveness, which is a major morphological feature of astrocytomas, involves interactions between tumour cell and extracellular matrix (ECM) including adhesion, proteolysis, and migration of tumour cells through the locally modified microenvironment. These interactions are mediated by cell/cell and cell/substrate adhesion molecules. We have earlier demonstrated that the adhesion molecule CD44 is expressed on gliomas and plays a role in adhesive interactions between glioma cells and a wide range of ECM components. In the present in vitro study we have further investigated the possible role of CD44 in subsequent stages of cell/ECM interactions-spreading and migration, using the GCCM anaplastic astrocytoma cell line. We have demonstrated that cell spreading is more effective on fibronectin (FN) than hyaluronan (HA) with a mean cell perimeter of 185 microns when cells are grown on FN as compared to 66 microns on HA. Antibody blockade experiments indicated that CD44 is not involved in cell spreading on either substrate. In the in vitro migration assay the tumour cells displayed a 2.5 fold greater migration rate through HA-coated as compared to FN-coated polycarbonate membranes. Blocking of CD44 by specific monoclonal antibody resulted in an inhibition of migration by 56% on HA providing evidence that CD44 plays a role in migration of astrocytoma cells in vitro.