Angiopoietins in malignancy

Abstract 

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.

Keyword: Angiopoietins, Cancer, Tumour vascularity

Abbreviations: Ang1, angiopoietin 1, Ang2, angiopoietin 2, Ang3, angiopoietin 3, Ang4, angiopoietin 4, EGF, epidermal growth factor, FGF, fibroblast growth factor, GS, Gleason score, HCC, hepatocellular cancer, MMP, matrix metalloproteinase, NSCLC, non-small cell lung carcinoma, OSCC, oral squamous cell carcinoma, PCR, polymerase chain reaction, PDGF, platelet derived growth factor, PECAM, platelet endothelial cells adhesion molecule, RT-PCR, reverse transcriptase polymerase chain reaction, SCC, squamous cell carcinoma, TGF-α, transforming growth factor-α, Tie1, Tie 1 receptor, Tie2, Tie 2 receptor, TNF-α, tumour necrosis factor-α, VEGF, vascular endothelial growth factor