Angiogenin: involvement in angiogenesis and tumour growth

Angiogenin is one of the most potent inducers of neovascularization in experimental models in vivo. Angiogenin is normally present in plasma but overexpressed in cancer patients. The possible involvement of angiogenin in the development of cancer is suggested by its overexpression in patients with a variety of tumours and the observation that angiogenin antagonists prevent the growth of human tumour xenografts in athymic mice. This 14.1-kDa protein has 35% amino acid sequence identity with human pancreatic ribonuclease and displays ribonucleolytic activity. As only angiogenin is able to induce angiogenesis, its biological activities are thought to result from structural characteristics. Although the structural characteristics of angiogenin have been extensively studied, the understanding of its physiological role and of how its properties are expressed is still to be deciphered. This article reviews some of the biological, biochemical and structural properties of angiogenin.