Cholesterol enhances thrombin-induced release of fibroblast growth factor-2 in human vascular smooth muscle cells.
OBJECTIVE
The mitogenic response to the G protein-coupled receptor agonist thrombin in human vascular smooth muscle cells (SMCs) depends on release of fibroblast growth factor-2 (FGF-2). Yet, intracellular mechanisms triggering FGF-2 release are unknown. The present study investigates possible effects of cholesterol enrichment and depletion, which have been shown to influence FGF-2-dependent signaling and SMC mitogenesis, on thrombin-induced FGF-2 release.


RESULTS
Cultured human aortic and saphenous vein SMCs were enriched with cholesterol by using a cyclodextrin-cholesterol complex. Cholesterol accumulation was determined by a fluorometric assay. ELISA, Western blotting, and RT-PCR were used for quantification of FGF-2 levels. DNA synthesis was determined by [3H]-thymidine incorporation, proliferation by cell counting. Stimulation of SMCs with thrombin (30 nmol/L) resulted in release of FGF-2 into the pericellular space within 10 minutes. Preincubation with cyclodextrin-cholesterol caused accumulation of cellular cholesterol, increased thrombin-induced FGF-2 release, and stimulated FGF-2 de novo synthesis. Thrombin-induced DNA synthesis and proliferation were enhanced in cholesterol-rich SMCs. This effect was inhibited by FGF-2-neutralizing antibodies.


CONCLUSIONS
Enhanced cellular cholesterol stimulates thrombin-induced release of FGF-2 and increases the mitogenic response toward thrombin in human SMCs. This mechanism might also be relevant for thrombin-induced mitogenesis in hypercholesterolemia in vivo.
Rauch
Bernhard H
BH
Universitätsklinikum Düsseldorf, Institut für Pharmakologie und Klinische Pharmakologie, Universiäts str. 1, 40225 Düsseldorf, Germany. rauchb@uni-duesseldorf.de
Scholz
Godehard A
GA
Baumgärtel-Allekotte
Dana
D
Censarek
Petra
P
Fischer
Jens W
JW
Weber
Artur-Aron
AA
Schrör
Karsten
K
D001011:Aorta / Q000166:cytology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002784:Cholesterol / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis; D004357:Drug Synergism; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006801:Humans; D008934:Mitogens / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012501:Saphenous Vein / Q000166:cytology; D013917:Thrombin / Q000494:pharmacology*; D047392:beta-Cyclodextrins / Q000494:pharmacology
D008934:Mitogens; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D016222:Fibroblast Growth Factor 2; D004247:DNA; D002784:Cholesterol; D013917:Thrombin