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

Yong Song; Xiao-Ping Zhao; Kai Song; Zheng-Jun Shang

doi:10.1371/journal.pone.0074464

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

PLoS One. 2013 Sep 9;8(9):e74464. doi: 10.1371/journal.pone.0074464. eCollection 2013.

Authors

Yong Song¹, Xiao-Ping Zhao, Kai Song, Zheng-Jun Shang

Affiliation

¹ The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine Ministry of Education, Wuhan University, Wuhan, China.

Abstract

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cell Hypoxia
Cell Line, Tumor
Cell Proliferation
Chromones / pharmacology
Coculture Techniques
Enzyme Inhibitors / pharmacology
Ephrin-A1 / genetics*
Ephrin-A1 / metabolism
Gene Expression Regulation, Neoplastic*
Human Umbilical Vein Endothelial Cells
Humans
Morpholines / pharmacology
NG-Nitroarginine Methyl Ester / pharmacology
Neovascularization, Pathologic / genetics*
Nitric Oxide / biosynthesis
Nitric Oxide Synthase Type III / antagonists & inhibitors
Nitric Oxide Synthase Type III / genetics*
Nitric Oxide Synthase Type III / metabolism
Phosphatidylinositol 3-Kinases / genetics
Phosphatidylinositol 3-Kinases / metabolism
Phosphoinositide-3 Kinase Inhibitors
Phosphorylation
Proto-Oncogene Proteins c-akt / antagonists & inhibitors
Proto-Oncogene Proteins c-akt / genetics
Proto-Oncogene Proteins c-akt / metabolism
Signal Transduction

Substances

Chromones
Enzyme Inhibitors
Ephrin-A1
Morpholines
Phosphoinositide-3 Kinase Inhibitors
Nitric Oxide
2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
NOS3 protein, human
Nitric Oxide Synthase Type III
Proto-Oncogene Proteins c-akt
NG-Nitroarginine Methyl Ester

Grants and funding

This study was supported by the National Natural Science Foundation of China (No. 81172570 and No. 30872893). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.