THE ROLE OF BASEMENT-MEMBRANE IN ANGIOGENESIS AND TUMOR-GROWTH

Expansion of the tumor-cell mass is dependent on both the degree of tu mor vascularization and the rate of angiogenesis. Blood vessel growth is controlled, in part, by the matrix surrounding it, in particular th e basement membrane underlying the endothelium. Here we illustrate tha t laminin, a major component of basement membrane, has several biologi cally active sites that can bind to endothelial and tumor cells, and h ave the ability to regulate angiogenesis and tumor growth. We show tha t synthetic peptides at two sites in the laminin B1 chain (the RGD and YIGSR sequences) inhibit angiogenesis, whereas a third site in the A chain, designated SIK-VAV, stimulates vessel and tumor cell growth. By developing strategies that promote or inhibit the activities of these sites in laminin, we may obtain methods to inhibit angiogenesis and s ubsequent tumor growth.