Nitric oxide in tumor angiogenesis.

Nitric oxide (NO), produced from L-arginine by NO synthases (NOS), is a short-lived molecule required for many physiological functions and contributing to different pathological conditions. In the last decade, we and others contributed to demonstrate that NO stimulates angiogenesis and mediates the effect of different angiogenic molecules. In human tumors, NOS expression and activity correlate with tumor growth and aggressiveness through angiogenesis stimulation and regulation of angiogenic factor expression. Interrelations among the NOS pathway, prostanoids and tyrosine kinase receptors have been reported in regulating tumor progression and malignancy. Drugs affecting the NOS pathway may be forseen as anti-tumor strategies able to reduce edema, inhibit angiogenesis and facilitate the delivery of chemotherapeutical agents. Recent developments include research on NOS gene polymorphisms which might become useful biomarkers for predicting cancer susceptibility as well as the role of NO in chemopreventive strategies.