DOMAINS OF TENASCIN INVOLVED IN GLIOMA MIGRATION

Tenascin (TN) is an extracellular matrix protein found in areas of cel l migration during development and expressed at high levels in migrato ry tumor cells. TN was previously shown to support the attachment and migration of glioma cells in culture. To determine the domains respons ible for glioma migration and attachment, we produced recombinant fusi on proteins that collectively span the majority of the molecule includ ing its epidermal growth factor-like repeats, fibronectin type III rep eats and fibrinogen domain. These domains were tested for their abilit y to support migration of C6 glioma cells in an aggregate migration as say. A recombinant fusion protein including fibronectin type III (FNII I) repeats 2-6 (TNfn2-6) was the only fragment found to promote migrat ion of C6 glioma cells at levels similar to that promoted by intact TN . Evaluation of smaller segments and individual FNIII repeats revealed that TNfn3 promoted migration and attachment of glioma cells and TNfn 6 promoted migration but not attachment. While TNfn3 and TNfn6 promote d migration individually, the presence of both TNfn3 and TNfn6 was req uired for migration on segments of the FNIII region that included TNfn 5. TNfn5 inhibited migration in a dose dependent manner when mixed wit h TNfn3 and also promoted strong attachment and spreading of C6 glioma cells. TNfn3 and TNfn6 promote cell migration and may function cooper atively to overcome the inhibitory activity of TNfn5. Additional cell attachment studies suggested that both beta 1 integrins and heparin ma y differentially influence the attachment of glioma cells to TN fragme nts. Together, these findings show that C6 glioma cells integrate thei r response upon binding to at least three domains within TN.