Blocking CLEC14A-MMRN2 binding inhibits sprouting angiogenesis and tumour growth

• Published in: Oncogene 2015-11, Vol.34 (47), p.5821-5831
• Main Authors: Noy, P J, Lodhia, P, Khan, K, Zhuang, X, Ward, D G, Verissimo, A R, Bacon, A, Bicknell, R
• Format: Article
• Language: English
• Subjects: 13/1; 13/106; 13/89; 631/1647; 631/208/68; 631/80/304; 631/80/84; 82/83; Analysis; Angiogenesis; Animals; Antibodies, Monoclonal - pharmacology; Antigens, Surface - metabolism; Aorta; Aorta - cytology; Apoptosis; Biomarkers; Cancer; Cell Adhesion Molecules - antagonists & inhibitors; Cell Adhesion Molecules - genetics; Cell Adhesion Molecules - metabolism; Cell Biology; Cell growth; Coculture Techniques; Endothelial cells; Gene Knockdown Techniques; Genetic aspects; Growth; Human Genetics; Human Umbilical Vein Endothelial Cells; Humans; Immunoprecipitation; Internal Medicine; Lectins, C-Type - antagonists & inhibitors; Lectins, C-Type - genetics; Lectins, C-Type - metabolism; Medicine; Medicine & Public Health; Membrane Glycoproteins - metabolism; Mice; Monoclonal antibodies; Neovascularization; Neovascularization, Pathologic; Oncology; original-article; Phenotypes; Protein Binding - drug effects; RNA, Small Interfering - pharmacology; Spheroids, Cellular - cytology; Tumors; Umbilical vein
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/onc.2015.34

We previously identified CLEC14A as a tumour endothelial marker. Here we show that CLEC14A is a regulator of sprouting angiogenesis in vitro and in vivo . Using a human umbilical vein endothelial cell spheroid-sprouting assay, we found CLEC14A to be a regulator of sprout initiation. Analysis of endothelial sprouting in aortic ring and in vivo subcutaneous sponge assays from clec14a +/+ and clec14a −/− mice revealed defects in sprouting angiogenesis in CLEC14A-deficient animals. Tumour growth was retarded and vascularity reduced in clec14a −/− mice. Pull-down and co-immunoprecipitation experiments confirmed that MMRN2 binds to the extracellular region of CLEC14A. The CLEC14A-MMRN2 interaction was interrogated using mouse monoclonal antibodies. Monoclonal antibodies were screened for their ability to block this interaction. Clone C4, but not C2, blocked CLEC14A-MMRN2 binding. C4 antibody perturbed tube formation and endothelial sprouting in vitro and in vivo , with a similar phenotype to loss of CLEC14A. Significantly, tumour growth was impaired in C4-treated animals and vascular density was also reduced in the C4-treated group. We conclude that CLEC14A-MMRN2 binding has a role in inducing sprouting angiogenesis during tumour growth, which has the potential to be manipulated in future antiangiogenic therapy design.