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.

AIM OF THE STUDY

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.

CONCLUSION

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.