Vitamin C promotes human endothelial cell growth via the ERK-signaling pathway.
BACKGROUND
Epidemiological, secondary prevention and small interventional trials suggest a preventive role of vitamin C for cardiovascular diseases (CAD), especially through improving endothelial dysfunction. Large primary prevention trials failed to confirm this. Mechanistic studies may contribute to resolve this discrepancy.


OBJECTIVE
We examined whether vitamin C activates mitogen-activated protein kinases (MAPK) in human umbilical cord venous endothelial cells (HUVECs) and whether reactive oxygen species (ROS) play a role in this process.


METHODS
Subconfluent quiescent HUVECs were incubated with vitamin C alone or in combination with catalase (CAT) and/or hydrogenperoxide (H2O2). Intracellular MAPK were determined by Western blot, proliferation by cell count and DNA-synthesis by [3H]-thymidine-uptake.


RESULTS
HUVECs were incubated with vitamin C (60 microM) for 5-60 min or for 20 min (30-90 microM). A dose-dependent phosphorylation of extracellular signal-regulated-kinases (ERKs)-1 and -2 with a maximum of phosphorylation at 15-20 min was observed and inhibitable by MEK1/2-inhibitor U0126 (5-10 microM). Vitamin C (60 microM) stimulated phosphorylation of ERK5, but not of p38 and c-Jun, demonstrating a different MAPK-activation pattern compared to H2O2. Vitamin C (60 microM) induced proliferation and a dose-dependent [3H]-thymidine-uptake (30-120 microM) within 20 h. CAT (0.3 U/ml) did neither suppress the vitamin C induced [3H]-thymidine-uptake nor ERK1/2-phosphorylation. CAT (0.3 U/ml), but not vitamin C (60 microM) abrogated the inhibitory effects of H2O2 (100 microM) on [3H]-thymidine-uptake.


CONCLUSIONS
Physiological vitamin C-concentrations promote proliferation of subconfluent ECs by activating an ERK1/2 controlled pathway. Targeting MAPK by vitamin C may improve, besides antioxidant mechanisms, endothelial dysfunction by promoting a fast regeneration of the endothelium after tissue injury, particularly required during secondary prevention and early development.
Ulrich-Merzenich
Gudrun
G
Medical Policlinic of the Rheinische, Friedrich-Wilhelms-University of Bonn, Wilhelmstr. 35-37 53111 Bonn, Germany. gudrun.ulrich-merzenich@ukb.uni-bonn.de
Zeitler
Heike
H
Panek
Darius
D
Bokemeyer
Dirk
D
Vetter
Hans
H
D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects*; D004247:DNA / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D000975:Antioxidants; D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; D017382:Reactive Oxygen Species; C113580:U 0126; D004247:DNA; D006861:Hydrogen Peroxide; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D001205:Ascorbic Acid