MOLECULAR MECHANISMS IN METASTASIS--ROLE OF FIBRONECTIN

Interstitial connective tissue, cell matrices, and basement membranes present significant barriers for normal, malignant, and metastatic cells. These structures can profoundly influence the phenotypic behavior of various cells. Specific molecules within cell matrices have the ability to promote cell growth, motility, differentiation, and cell invasiveness. Understanding the effects of specific molecular components of basement membranes and cell matrices on the behavior of metastatic cells is not only key to understanding the process, but also to understanding how to potentially control the spread of malignant cells. We will characterize and synthesize novel peptides from the 33 kD heparin binding region of fibronectin to determine binding conditions, and specificity of glycosaminoglycan peptide binding using dextran, dermatan/chondroitin sulfate and heparin. Next, we will determine whether peptides directly promote adhesion of metastatic cells and determine the affinity of cell binding to 33 kD fragment and peptides derived from it. These peptides will next be tested to determine collagen gel or aminon basement membrane; cell motility; experimental tumor metastasis in vivo; tumorigenicity; colony formation in soft agar; pulmonary retention of radiolabeled cells in vivo. Next, we will perform structural-functional analysis of active peptides by substituting or modifying the amino acids to determine the minimal amino acid sequence(s) capable of: modifying cell adhesion, invasion, migration; or modifying experimental tumor metastasis. Polyclonal and monoclonal antibodies will be developed to active peptides to determine if these antibodies "block" any specific functional activities of intact fibronectin or the 33 kD fragment. Next, the membrane binding components or "receptors" for the biologically active peptides will be isolated using a variety of methods as described. Lastly, we will develop polyclonal and monoclonal antibodies to the metastatic cell plasma membrane binding components and assay these antibodies for their ability to modify: a) cell adhesion, b) cell spreading, c) cell invasion, and d) experimental tumor metastasis.