A Role of Agrin in Maintaining the Stability of Vascular Endothelial Growth Factor Receptor-2 during Tumor Angiogenesis Kizito Njah, Sayan Chakraborty, Beiying Qiu, Guillaume Thibault, Xiaomeng Wang, Wanjin Hong Open Access DOI:https://doi.org/10.1016/j.celrep.2019.06.036
Endothelial cell (EC) recruitment is central to the vascularization of tumors. Although several proteoglycans have been implicated in cancer and angiogenesis, their roles in EC recruitment and vascularization during tumorigenesis remain poorly understood. Here, we reveal that Agrin, which is secreted in liver cancer, promotes angiogenesis by recruiting ECs within tumors and metastatic lesions and facilitates adhesion of cancer cells to ECs. In ECs, Agrin-induced angiogenesis and adherence to cancer cells are mediated by Integrin-β1, Lrp4-MuSK pathways involving focal adhesion kinase. Mechanistically, we uncover that Agrin regulates VEGFR2 levels that sustain the angiogenic property of ECs and adherence to cancer cells. Agrin attributes an ECM stiffness-based stabilization of VEGFR2 by enhancing interactions with Integrin-β1-Lrp4 and additionally stimulates endothelial nitric-oxide synthase (e-NOS) signaling. Therefore, we propose that cross-talk between Agrin-expressing cancer and ECs favor angiogenesis by sustaining the VEGFR2 pathway.
The study was funded in part by the Open-Fund Young Investigator Grant from the National Medical Research Council (NMRC, Singapore) (NMRC/OFYIRG/068/2018-00) to S.C. and Agency for Science, Technology and Research (A-STAR) core funds to S.C. and W.H. We thank the Advanced Molecular Pathology laboratory at IMCB for assistance in immunohistochemistry.