HB-EGF promotes angiogenesis in endothelial cells via PI3-kinase and MAPK signaling pathways

Objective: Heparin-binding EGF-like growth factor (HB-EGF) belongs to the epidermal growth factor (EGF) superfamily of ligands. It has been implicated as a regulator of angiogenesis. However, the mechanisms by which HB-EGF promotes angiogenesis are unknown. The goal of the present study was to define the pathways by which HB-EGF stimulates angiogenesis in endothelial cells. Methods: To characterize the angiogenic activity of HB-EGF, we treated human umbilical vein endothelial cells (HUVEC) with HB-EGF and analyzed the effects on cell proliferation, migration and tube formation. Side-by-side assays with EGF were used for comparison. Results: Both HB-EGF and EGF stimulated HUVEC migration in scratch assays and promoted vascular tube formation in 2D-angiogenesis assays, without inducing cell proliferation. HB-EGF- and EGF-induced HUVEC migration and capillary tube formation were dependent upon activation of PI3K, MAPK and eNOS. Importantly, HB-EGF-and EGF-induced tube formation was comparable to, but were independent of tube formation induced by VEGF. Conclusions: We have demonstrated that HB-EGF and EGF induce angiogenesis via activation of PI3K, MAPK and eNOS in a VEGF-independent fashion. Thus, the role played by HB-EGF in stimulating physiologic processes such as wound healing in vivo may be dependent, in part, on its ability to promote angiogenesis.