Overview of angiogenesis during tumor growth

Abstract

In tumors, the phenotypic switch to angiogenesis involves more than simple up-regulation of angiogenic activity and is thought to be the result of a net balance of positive and negative regulators. Tumor angiogenesis is regulated by several factors, including growth factors for the endothelial cells secreted by both the tumor and stromal inflammatory cells, and mobilized from extracellular matrix stores by proteases secreted by tumor cells. Regulatory factors also include the extracellular matrix components and endothelial cell integrins, hypoxia, oncogenes and tumor suppressor genes. Angiogenesis is mandatory for tumor progression, in the form of growth, invasion and metastasis; hence it has prognostic value. © 2008 Springer US.