Involvement of COX‐2/PGE2 signalling in hypoxia‐induced angiogenic response in endothelial cells

Lixing Zhao,Yeke Wu,Yu Li,Pu Yang,Zhihe Zhao,Xing Wei,Zhenrui Xu,Hui Wang

doi:10.1111/j.1582-4934.2011.01479.x

Lixing Zhao, Yeke Wu + Show 6 more

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https://doi.org/10.1111/j.1582-4934.2011.01479.x

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Abstract

To evaluate the impact of hypoxia on the angiogenic capability of endothelial cells (ECs), and further investigate whether the cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) signalling is involved in the angiogenic response of ECs to hypoxia. We explored the impact of various periods (1, 3, 6, 12, 24 hrs) of hypoxia (2% O2) on human umbilical vein endothelial cells (HUVECs) in vitro. We observed cell viability, migration, tube formation, analysed COX-2, vascular endothelial growth factor (VEGF), AQP1 mRNA transcription, protein expression and measured PGE2, VEGF protein concentration in cell supernatants. Then we treated HUVECs with COX-2 selective inhibitor NS398, EP1/2 combined antagonist AH6809 and exogenous PGE2 to investigate the role of COX-2/PGE2 signalling in the angiogenic response of ECs to hypoxia. The results demonstrated that short-term hypoxic treatment enhanced HUVECs proliferation, migration, tube formation, significantly up-regulated COX-2, VEGF, AQP1 mRNA level, protein expression and promoted PGE2, VEGF release. The pharmacological inhibition study revealed that exposure of HUVEC to NS398 and AH6809 under hypoxia impaired the biological responses of ECs to hypoxia. Exogenous PGE2 augments the effects of hypoxia on HUVECs, and partially reversed the inhibitory effects of NS398 on HUVECs proliferation and angiogenic capability. Short-term hypoxic treatment enhanced angiogenic capability of ECs, and COX-2/PGE2 signalling may play a critical role in the biological response of ECs to hypoxia.

Highlights

Angiogenesis, formation of new capillaries which enables delivery of oxygen and nutrients, is essential for tumour growth and metastasis [1], ischaemic disorder recovering [2] and periodontal tissue remodelling [3]
In order to better understand how ECs adapt to hypoxic environment, we explored the impact of hypoxia on the human umbilical vein endothelial cells (HUVECs) by observing cell viability, migration, tube formation, analysing COX-2, vascular endothelial growth factor (VEGF) and AQP1 expression and measuring PGE2, VEGF concentration in supernatants of HUVECs with different periods of hypoxic treatment
We found that hypoxia induced migration of HUVECs in a time-dependent manner

Summary

Introduction

Angiogenesis, formation of new capillaries which enables delivery of oxygen and nutrients, is essential for tumour growth and metastasis [1], ischaemic disorder recovering [2] and periodontal tissue remodelling [3]. It is a highly organized process and involves a complex sequence of steps that include endothelial cells (ECs) proliferation, maturation and assembly [4]. As the main cell type involved in angiogenesis, ECs migrate from capillaries toward the Hypoxia is a characteristic feature of many physiological or pathological processes in vivo: driving angiogenesis in tumours [7], taking part in ischaemic diseases [8] and participating in bony or soft tissue injury [9]. The mechanism of hypoxia-driven angiogenesis and the role of inflammatory mediators in the biological response of ECs to hypoxia remains unclear

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