title: Piper sarmentosum inhibits ICAM-1 and Nox4 gene expression in oxidative stress-induced human umbilical vein endothelial cells.
abstract: BACKGROUND
  Aqueous extract of Piper sarmentosum (AEPS) is known to possess antioxidant and anti-atherosclerotic activities but the mechanism responsible for it remains unclear. In early part of atherosclerosis, nuclear factor-kappa B (NF-κB) induces the expression of cellular adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1) and E-selectin. NADPH oxidase 4 (Nox4) is the predominant source of superoxide in the endothelial cells whereas superoxide dismutase 1 (SOD1), catalase (CAT) and glutathione peroxidase (GPx) are the antioxidant enzymes responsible for inactivating reactive oxygen species. The present study aimed to investigate the effects of AEPS on the gene expression of NF-κB, VCAM-1, ICAM-1, E-selectin, Nox4, SOD1, CAT and GPx in cultured human umbilical vein endothelial cells (HUVECs).
  
  
  METHODS
  HUVECs were divided into four groups:- control; treatment with 180 μM hydrogen peroxide (H₂O₂); treatment with 150 μg/mL AEPS and concomitant treatment with AEPS and H₂O₂ for 24 hours. Total RNA was extracted from all the groups of HUVEC using TRI reagent. Subsequently, qPCR was carried out to determine the mRNA expression of NF-κB, VCAM-1, ICAM-1, E-selectin, Nox4, SOD1, CAT and GPx. The specificity of the reactions was verified using melting curve analysis and agarose gel electrophoresis.
  
  
  RESULTS
  When stimulated with H₂O₂, HUVECs expressed higher level of ICAM-1 (1.3-fold) and Nox4 (1.2-fold) mRNA expression. However, AEPS treatment led to a reduction in the mRNA expression of ICAM-1 (p < 0.01) and Nox4 (p < 0.05) in the H₂O₂-induced HUVECs. AEPS also upregulated the mRNA expression of SOD1 (p < 0.05), CAT (p < 0.01) and GPx (p < 0.05) in oxidative stress-induced HUVECs. There was no significant change in the mRNA expression of VCAM-1 and E-selectin.
  
  
  CONCLUSIONS
  The expressional suppression of ICAM-1 and Nox4 and induction of antioxidant enzymes might be an important component of the vascular protective effect of AEPS.
authors.affiliation: Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
authors.forename: Azizah
authors.initials: A
authors.lastname: Ugusman
authors.forename: Zaiton
authors.initials: Z
authors.lastname: Zakaria
authors.forename: Chua Kien
authors.initials: CK
authors.lastname: Hui
authors.forename: Nor Anita Megat Mohd
authors.initials: NA
authors.lastname: Nordin
mesh_terms: D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D031701:Piper; D010936:Plant Extracts / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D012333:RNA, Messenger; C000606290:SOD1 protein, human; D018799:Intercellular Adhesion Molecule-1; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D019255:NADPH Oxidases