Angiopoietins in malignancy

Background: Tumour growth is dependant upon the development of an adequate blood supply. This, in turn, is thought to depend upon a switch by the tumour, from a dormant to angiogenic state. Recent data suggest that this switch may occur when the balance of pro- and anti-angiogenic agents alters to promote angiogenesis. Angiopoietins may be involved in this balance. Methods: An electronic literature search was performed with respect to angiopoietins from 1996 to the present. Published data from in-vitro and in-vivo studies were critically analysed. A specific focus was made of studies relating to tumour growth and vasculature. Results: Since angiopoietin-1 was first described in 1996, three more angiopoietins have been described. All family members bind to the Tie-2 receptor. There is now a considerable accumulation of data that suggests they play a pivotal role in the development and stabilisation of tumour vasculature. angiopoietin-2 appears to be pro-angiogenic whilst angiopoietin-1 appears to be a stabilising factor. Conclusions: Recent trials of anti-angiogenic agents show promise in the treatment of solid human cancers. The angiopoietins are a new family of proteins that appear to be influential in the development of the tumour vasculature. Manipulation of the angiopoietin balance may provide a potential therapeutic target in human cancer. (C) 2006 Elsevier Ltd. All rights reserved.