Andrographolide inhibits hypoxia‐induced HIF‐1α‐driven endothelin 1 secretion by activating Nrf2/HO‐1 and promoting the expression of prolyl hydroxylases 2/3 in human endothelial cells

• Published in: Environmental toxicology 2017-03, Vol.32 (3), p.918-930
• Main Authors: Lin, Hung‐Chih, Su, Shih‐Li, Lu, Chia‐Yang, Lin, Ai‐Hsuan, Lin, Wan‐Chun, Liu, Chin‐San, Yang, Ya‐Chen, Wang, Hsiu‐Miao, Lii, Chong‐Kuei, Chen, Haw‐Wen
• Format: Article
• Language: English
• Subjects: Andrographis paniculata; andrographolide; Cell Hypoxia; Cell Line; Cell Survival - drug effects; Cobalt - toxicity; Diterpenes - pharmacology; Endothelial Cells - cytology; Endothelial Cells - metabolism; endothelin 1 (ET‐1); Endothelin-1 - genetics; Endothelin-1 - metabolism; heme oxygenase 1 (HO‐1); Heme Oxygenase-1 - antagonists & inhibitors; Heme Oxygenase-1 - genetics; Heme Oxygenase-1 - metabolism; Humans; Hydroxylation; Hypoxia-Inducible Factor 1, alpha Subunit - metabolism; hypoxia‐inducible factor 1α (HIF‐1α); NF-E2-Related Factor 2 - antagonists & inhibitors; NF-E2-Related Factor 2 - genetics; NF-E2-Related Factor 2 - metabolism; Nrf2; p38 Mitogen-Activated Protein Kinases - metabolism; prolyl hydroxylases (PHDs); Prolyl Hydroxylases - genetics; Prolyl Hydroxylases - metabolism; Reactive Oxygen Species - metabolism; RNA Interference; RNA, Messenger - metabolism; RNA, Small Interfering - metabolism; Signal Transduction - drug effects
• ISSN: 1520-4081; 1522-7278
• DOI: 10.1002/tox.22293

ABSTRACT Andrographolide, the main bioactive component of the medicinal plant Andrographis paniculata, has been shown to possess potent anti‐inflammatory activity. Endothelin 1 (ET‐1), a potent vasoconstrictor peptide produced by vascular endothelial cells, displays proinflammatory property. Hypoxia‐inducible factor 1α (HIF‐1α), the regulatory member of the transcription factor heterodimer HIF‐1α/β, is one of the most important molecules that responds to hypoxia. Changes in cellular HIF‐1α protein level are the result of altered gene transcription and protein stability, with the latter being dependent on prolyl hydroxylases (PHDs). In this study, inhibition of pro‐inflammatory ET‐1 expression and changes of HIF‐1α gene transcription and protein stability under hypoxia by andrographolide in EA.hy926 endothelial‐like cells were investigated. Hypoxic conditions were created using the hypoxia‐mimetic agent CoCl2. We found that hypoxia stimulated the production of reactive oxygen species (ROS), the expression of HIF‐1α mRNA and protein, and the expression and secretion of ET‐1. These effects, however, were attenuated by co‐exposure to andrographolide, bilirubin, and RuCO. Silencing Nrf2 and heme oxygenase 1 (HO‐1) reversed the inhibitory effects of andrographolide on hypxoia‐induced HIF‐1α mRNA and protein expression. Moreover, andrographolide increased the expression of prolyl hydroxylases (PHD) 2/3, which hydroxylate HIF‐1α and promotes HIF‐1α proteasome degradation, with an increase in HIF‐1α hydroxylation was noted under hypoxia. Inhibition of p38 MAPK abrogated the hypoxia‐induced increases in HIF‐1α mRNA and protein expression as well as ET‐1 mRNA expression and secretion. Taken together, these results suggest that andrographolide suppresses hypoxia‐induced pro‐inflammatory ET‐1 expression by activating Nrf2/HO‐1, inhibiting p38 MAPK signaling, and promoting PHD2/3 expression. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 918–930, 2017.