Miltirone protects human EA.hy926 endothelial cells from oxidized low-density lipoprotein-derived oxidative stress via a heme oxygenase-1 and MAPK/Nrf2 dependent pathway

Phytomedicine. 2016 Dec 15;23(14):1806-1813. doi: 10.1016/j.phymed.2016.11.003. Epub 2016 Nov 4.

Abstract

Background: Oxidized low-density lipoprotein (ox-LDL) is an underlying cause of endothelial dysfunction, which is an early event in the pathogenesis of atherosclerosis. In our previous study, we established an ARE-driven luciferase reporter system and screened out several potential Nrf2 activators from Salvia miltiorrhiza Bunge.

Purpose: Since miltirone showed the most potent ARE-driven luciferase activity, the aim of this study was to test the protective role of miltirone against oxidative stress in endothelial cell and to investigate the underlying mechanistic signaling pathways.

Study design/method: In the present study, miltirone increased the expression of nuclear translocation and transcriptional activities of NF-E2-related factor 2 (Nrf2), which led to augmented expression of antioxidant-response element (ARE)-dependent heme oxygenase-1 (HO-1) and NAD(P)H-quinone oxidoreductase 1 (NQO1). Inhibition of Nrf2/HO-1 by RNA interference abolished miltirone-induced cytoprotective effects against ox-LDL, which suggested that Nrf2 and the downstream expression of HO-1 are required for the functional effects of miltirone. Ox-LDL-stimulated mitogen-activated protein kinase activation, ROS production, and miltirone dramatically inhibited synthesis of ROS, as well as decreased SOD and glutathione S-transferase (GST) in human EA.hy926 endothelial cells.

Results: Miltirone-induced Nrf2 and HO-1 expression was related to mitogen-activated protein kinase (MAPK) pathways. The activation of MAPK was partially dependent on the phosphorylation of the c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) pathways, but not P38 MAPK signaling. However, miltirone-induced Nrf2/HO-1 expression can only be effectively blocked by JNK inhibitor SP600125.

Conclusion: Our findings reveal that miltirone exerts protective functions on endothelial cells in response to ox-LDL-induced oxidative stress, and does so via Nrf2/HO-1, which provides novel insights into the antioxidant capacity of miltirone.

Keywords: Endothelial dysfunction; HO-1; Miltirone; Nrf2; Oxidative stress.

MeSH terms

  • Antioxidant Response Elements
  • Antioxidants / pharmacology
  • Atherosclerosis / metabolism
  • Cell Line
  • Endothelial Cells / drug effects*
  • Endothelial Cells / metabolism
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Glutathione Transferase / metabolism
  • Heme Oxygenase-1 / metabolism*
  • Humans
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Lipoproteins, LDL / metabolism*
  • MAP Kinase Signaling System / drug effects*
  • NF-E2-Related Factor 2 / metabolism*
  • Oxidative Stress / drug effects*
  • Phenanthrenes / pharmacology*
  • Plant Extracts / pharmacology
  • Salvia miltiorrhiza / chemistry
  • Signal Transduction / drug effects
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Antioxidants
  • Lipoproteins, LDL
  • NF-E2-Related Factor 2
  • Phenanthrenes
  • Plant Extracts
  • oxidized low density lipoprotein
  • miltirone
  • Heme Oxygenase-1
  • Glutathione Transferase
  • Extracellular Signal-Regulated MAP Kinases
  • JNK Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases