Summary
Background
It is generally accepted that angiogenesis is a complex and tightly regulated process characterized by the growth of blood vessels from existing vasculature. Activation of the Notch signalling pathway affects multiple aspects of vascular development. One of the components of the Notch signalling pathway, Delta-like ligand 4 (DLL4), has recently appeared as a critical regulator of tumour angiogenesis and thus as a promising therapeutic target.
Methods
This review article includes available data from peer-reviewed publications associated with the role of DLL4 in cancer angiogenesis. Searches were performed in PubMed, EMBASE, Google Scholar and Web of Science using the terms “tumour angiogenesis”, “DLL4”, “Notch signalling” and “anti-cancer therapy”.
Results
The survival curves of cancer patients revealed that the patients with high DLL4 expression levels had significantly shorter survival times than the patients with low DLL4 expression. Moreover, a positive correlation was also identified between DLL4 and VEGF receptorsʼ expression levels. It seems that inhibition of DLL4 may exert potent growth inhibitory effects on some tumours resistant to anti-VEGF therapies. A great number of blocking agents of DLL4/Notch signalling including anti-DLL4 antibodies, DNA vaccination, Notch antibodies and gamma-secretase inhibitors have been studied in preclinical tumour models.
Conclusion
DLL4 seems to be a promising target in anti-cancer therapy. Nevertheless, the careful evaluation of adverse effects on normal physiological processes in relation to therapeutic doses of anti-DLL4 drugs will be significant for advancement of DLL4 blocking agents in clinical oncology.
Vascular endothelial growth factor reduces mural cell coverage of endothelial cells and induces sprouting rather than luminal division in an HT1080 tumour angiogenesis model