Chapter 4 - Therapeutic Implications of the Nitric Oxide Pathway in the Angiogenesis of Tumors and Inflammatory-Related Disorders

Abstract

Not only is angiogenesis, the development of new vessels from preexisting ones, a prerequisite for the physiological growth, repair, and functioning of our organs, but also it concurs, as examples, with the pathologies of cancer, eye diseases, and chronic degenerative disorders. In most of the pathological conditions, an inflammatory and oxidative state exists, supporting deregulation of angiogenesis. Endothelial cells, the core of angiogenesis, produce nanomolar levels of nitric oxide (NO), guaranteeing proper vessel tone, blood fluidity, and a noninflammatory environment. In contrast, in the presence of a growing tumor or pathological conditions related to inflammation and redox imbalance, higher (micromolar) NO levels are present, contributing to the development of an aberrant neovascularization. Nevertheless, the use of NO donor drugs is proposed in some types of tumors as an antitumor/antiangiogenic strategy. The focus of this review will be on the role and activities elicited by the NOS pathway in pathological angiogenesis, speculating on the likely therapeutic outcomes.