title: Initial response of endothelial cells to acute stimulation with a lipid component: increase cyclooxygenase activity by induction of COX-2 through activation of tyrosine kinase.
abstract: OBJECTIVE
  To study the initial response of endothelial cells acutely stimulated with a lipid component in the aspect of cyclooxygenase (COX) function which needed for prostacyclin synthesis, an endogenous antiatherogenic agent secreted from endothelial cells.
  
  
  METHODS
  25 hydroxycholesterol (25OHC) was used as a representative lipid component for stimulating human umbilical vein endothelial cell (HUVEC) obtained from umbilical cords of healthy newborns with informed consent of their mothers. HUVEC were treated with 25OHC (0.1, 1 or 10 microgram/mL) at times 6, or 24 h. COX activity was measured from amount of 6-keto-PGF(1 alfa) production in the presence of exogenous arachidonic acids (10 micromolar; 10 min) by enzyme immunoassay. The amount of COX-1 and COX-2 protein were detected by Western blot. Cell viability was assessed by using MTT assay.
  
  
  RESULTS
  25OHC induced COX-2 protein production with increasing the activity of COX enzyme in HUVEC without change in amount of COX-1 protein. The induction of COX-2 or increasing in COX activity depended on concentration of 25OHC and time to exposure which seemed to be inhibited by genistein, a specific tyrosine kinase inhibitor.
  
  
  CONCLUSIONS
  Acute stimulation of HUVEC with 25OHC, an atherosclerotic lipid component, increases the activity of COX by inducing COX-2 expression in a manner that depended on concentration and time. The induction of COX-2 expression might possibly mediated through activation protein tyrosine kinase. These responses may be an initial defensive mechanism of endothelial cells from lipid component attack.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand. duangpor@swu.ac.th
authors.forename: Duangporn
authors.initials: D
authors.lastname: Plasen
authors.forename: Pravit
authors.initials: P
authors.lastname: Akarasereenont
authors.forename: Kitirat
authors.initials: K
authors.lastname: Techatraisak
authors.forename: Sirikul
authors.initials: S
authors.lastname: Chotewuttakorn
authors.forename: Athiwat
authors.initials: A
authors.lastname: Thaworn
mesh_terms: D015121:6-Ketoprostaglandin F1 alpha / Q000096:biosynthesis / Q000378:metabolism; D000959:Antihypertensive Agents / Q000378:metabolism; D001095:Arachidonic Acids; D015153:Blotting, Western; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D011464:Epoprostenol / Q000096:biosynthesis / Q000378:metabolism; D019833:Genistein / Q000378:metabolism; D006801:Humans; D006888:Hydroxycholesterols / Q000494:pharmacology*; D007124:Immunoenzyme Techniques; D007231:Infant, Newborn; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D047428:Protein Kinase Inhibitors; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D013997:Time Factors; D014471:Umbilical Veins / Q000166:cytology / Q000378:metabolism
chemical_list: D000959:Antihypertensive Agents; D001095:Arachidonic Acids; D006888:Hydroxycholesterols; D047428:Protein Kinase Inhibitors; D015121:6-Ketoprostaglandin F1 alpha; C007997:25-hydroxycholesterol; D011464:Epoprostenol; D019833:Genistein; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D011505:Protein-Tyrosine Kinases