Angiostatin: A Circulating Endothelial Cell Inhibitor That Suppresses Angiogenesis and Tumor Growth
This extract was created in the absence of an abstract.
Excerpt
INTRODUCTION
Prevascular and Vascular Stages of Tumor Growth
A central problem in tumor growth is how tumor cells switch to the angiogenic phenotype. Virtually all solid tumors are angiogenic and neovascularized by the time they are detectable in animals and humans. However, at the time they originate, spontaneously arising tumor cells are not usually angiogenic (Folkman et al. 1989). Tumors formed by these cells are of small volumes limited to a few cubic millimeters and restricted to an existence in this in situ stage for months or years. Further expansion of such a tumor depends on its induction of new capillary blood vessels that converge toward the tumor. This switch to angiogenesis is usually accomplished by a subset of tumor cells within the in situ lesion. The new microvessels that are recruited provide a neovascular meshwork which supports the growth, and facilitates invasion and metastasis of the rapidly expanding tumor...