Matrix-degrading proteases and angiogenesis during development and tumor formation

Embryonic development and tumor progression both require the exquisite coor dination of programs for extracellular matrix (ECM) formation and remodelin g, and those for angiogenesis and vascular development. Without a vascular supply the normal tissue or tumor is limited in size and organization. With out ECM remodeling the alteration of tissue and tumor boundaries and cellul ar migrations are limited. Recent insights into the molecular mechanisms re gulating the extracellular environment of the growing embryonic tissue or t umors have implicated proteases, the matrix metalloproteinases (MMPs) in pa rticular, in both the process of ECM remodeling and angiogenesis, and in a potential causal relationship between these processes. This review focuses on the roles that MMPs play in regulating three processes in which both pro teolysis and vascular development are tightly coordinated: embryo implantat ion, bone development and tumor progression.