Ephrin-A1 is up-regulated by hypoxia in cancer cells and promotes angiogenesis of HUVECs through a coordinated cross-talk with eNOS

• Published in: PloS one 2013-09, Vol.8 (9), p.e74464-e74464
• Main Authors: Song, Yong, Zhao, Xiao-Ping, Song, Kai, Shang, Zheng-Jun
• Format: Article
• Language: English
• Subjects: 1-Phosphatidylinositol 3-kinase; AKT protein; Analysis; Angiogenesis; Apoptosis; Arginine; Cancer; Cell adhesion & migration; Cell culture; Cell Hypoxia; Cell Line, Tumor; Cell Proliferation; Chromones - pharmacology; Coculture Techniques; Education; Endothelial cells; Endothelium; Enzyme inhibitors; Enzyme Inhibitors - pharmacology; Ephrin-A1 - genetics; Ephrin-A1 - metabolism; Gene Expression Regulation, Neoplastic; Growth factors; Human Umbilical Vein Endothelial Cells; Humans; Hypoxia; Inhibitors; Kinases; Laboratories; Ligands; Morpholines - pharmacology; Neovascularization; Neovascularization, Pathologic - genetics; NG-Nitroarginine methyl ester; NG-Nitroarginine Methyl Ester - pharmacology; Nitric oxide; Nitric Oxide - biosynthesis; Nitric Oxide Synthase Type III - antagonists & inhibitors; Nitric Oxide Synthase Type III - genetics; Nitric Oxide Synthase Type III - metabolism; Nitric-oxide synthase; Phosphatidylinositol 3-Kinases - antagonists & inhibitors; Phosphatidylinositol 3-Kinases - genetics; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation; Proto-Oncogene Proteins c-akt - antagonists & inhibitors; Proto-Oncogene Proteins c-akt - genetics; Proto-Oncogene Proteins c-akt - metabolism; Rodents; Science; Signal Transduction; Squamous cell carcinoma; Transcription factors; Tumor necrosis factor-TNF; Umbilical vein; Vascularization
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0074464

Hypoxia, ephrin-A1 and endothelial nitric oxide synthase (eNOS) have been proved to play critical roles in tumor angiogenesis. However, how ephrin-A1 is regulated by hypoxia and whether ephrin-A1 cooperates with eNOS in modulation of angiogenesis remain to be addressed in details. Here we demonstrated that both ephrin-A1 in squamous cell carcinoma cells (SCC-9) and especially soluble ephrin-A1 in the supernatants were up-regulated under hypoxic condition. An increased nitric oxide (NO) production in human umbilical vein endothelial cells (HUVECs) was observed in ephrin-A1-induced angiogenesis which was reversed after co-culture with eNOS specific inhibitor, N-nitro-L-arginine methyl ester hydrochloride (L-NAME). Western blot analysis confirmed that both phosphorylation of Akt(Ser473) and eNOS(Ser1177) were up-regulated in ephrin-A1-stimulated HUVECs, with the total eNOS expression unchanged. The specific inhibitor of phosphatidylinositol 3-kinase (PI3K), LY294002, significantly down-regulated ephrin-A1-induced expression of phosphorylated Akt(Ser473) as well as phosphorylation of eNOS(Ser1177). These results revealed a possible novel mechanism whereby ephrin-A1 is regulated in tumor microenvironment and promotes angiogenesis through a coordinated cross-talk with PI3K/Akt-dependent eNOS activation which may relate to normal vascular development and tumor neovascularization.