N‐myc downstream regulated gene‐1 promotes vascular inflammation through activating both NF‐κB and c‐Jun/AP‐1 pathways in endothelial cells

Abstract

ObjectiveN‐myc downstream regulated gene‐1(NDRG‐1) is a member of NDRG family that has been shown to play essential roles not only in the regulation of cancer metastasis but also in the development of cardiovascular diseases, such as atherosclerosis and thrombus. The objective of this study is to determine whether NDRG1 is involved in vascular endothelial cell (EC) activation, and if so, to determine the molecular mechanism (s) involved.Methods and ResultsIn response to the stimulation of inflammatory cytokines, such as interleukin‐1β (IL‐1β) and tumor necrosis factor‐alpha (TNF‐α), we show that the expression of NDRG1 in vascular ECs was markedly increased in a dose and time‐dependent manner, as determined by both quantitative real‐time PCR (qRT‐PCR) and western blot analysis. To determine the role of NDRG1 in endothelial activation, we performed a loss‐of‐function study by using NDRG1 specific small interference RNA (siRNA). Our results demonstrate that knockdown of NDRG1 in vascular ECs by siRNA substantially attenuates both IL‐1β and TNF‐α‐induced inflammatory responses in human umbilical vein endothelial cells (HUVECs). The expression of inflammatory cytokines and chemokines, such as IL‐6, IL‐8, and MCP‐1, was markedly inhibited in NDRG1 knockdown ECs. Intriguingly, the IL‐1β‐induced expression of thrombotic markers, such as plasminogen activator inhibitor type 1 (PAI‐1) and tissue factor (TF), was also attenuated in NDRG1 knockdown cells. To further elucidate the functional significance of NDRG1 in vivo, we assessed the expression of NDRG1 in the vessels subjected to the carotid artery ligation‐induced injury. Our results demonstrate that the expression of NDRG1 was markedly increased in the injured vessels as compared with their un‐injured controls. Furthermore, we found that in a mouse model of carotid artery ligation induced injury, knockdown of NDRG1 expression substantially attenuates vascular remodeling, as manifested by decreased neointimal formation, microphage infiltration, and expression of adhesion molecules in injured arteries. Mechanistically, we found that inhibition of NDRG1 markedly inhibited the transcriptional activities of both NF‐κB and AP‐1 pathways in vascular ECs, as determined by both promoter‐driven luciferase and electrophoretic mobility shift assays.ConclusionTaken together, our results for the first time identify NDRG1 as a critical regulator implicated in vascular inflammation and remodeling, and suggest that targeted inhibition of NDRG1 in vasculature may represent a novel therapeutic strategy for preventing certain cardiovascular diseases, such as atherosclerosis and thrombosis.Support or Funding InformationNIH:RO1 HL103869‐01, NSCF: 81541003, SHSCF:15ZR1413400