3',4'-Dihydroxyflavonol down-regulates monocyte chemoattractant protein-1 in smooth muscle: role of focal adhesion kinase and PDGF receptor signalling.
OBJECTIVE
We investigated the effects of a synthetic flavonol, 3',4'-dihydroxyflavonol (DiOHF) on the expression of monocyte chemoattractant protein-1 (MCP-1) in rat vascular smooth muscle cells.


METHODS
MCP-1 expression was assessed by quantitative real-time PCR and protein phosphorylation by immunoprecipitation and Western blots.


RESULTS
DiOHF (1-30 micromol x L(-1)) concentration-dependently reduced MCP-1 expression in both quiescent cells and cells stimulated with platelet-derived growth factor (PDGF) or interleukin 1-beta. The effect of DiOHF was associated with a suppression of focal adhesion kinase (FAK)-mediated signalling. In vitro kinase assays demonstrated that DiOHF is a potent inhibitor of FAK kinase activity (EC(50)= 2.4 micromol x L(-1)). Expression of FAK-related non-kinase reduced basal MCP-1 expression, but not that induced by PDGF or interleukin 1-beta. DiOHF also inhibited autophosphorylation of PDGF receptors. The PDGF receptor inhibitor AG-1296 potently suppressed basal and PDGF-induced MCP-1 expression. Inhibition of extracellular signal-regulated kinase activation by DiOHF, either directly or indirectly, may also be involved in its effects on MCP-1 expression. DiOHF had no inhibitory effect on either p38 or nuclear factor-kappaB activation. Moreover, DiOHF inhibited smooth muscle cell spreading (a FAK-mediated response) and proliferation.


CONCLUSIONS
This is the first report on a flavonoid compound (DiOHF) that is a potent FAK inhibitor. DiOHF also inhibits PDGF receptor autophosphorylation. These effects underlie the inhibitory action of DiOHF on MCP-1 expression in smooth muscle cells. Our results suggest that DiOHF might be a useful tool for dissection of the (patho)physiological roles of FAK signalling.
Bernard O'Brien Institute of Microsurgery, University of Melbourne, Victoria, Australia. fjiang@unimelb.edu.au
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D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000096:biosynthesis*; D016207:Cytokines / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects*; D044948:Flavonols / Q000494:pharmacology*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D018932:Chemokine CCL2; D016207:Cytokines; D044948:Flavonols; D016328:NF-kappa B; C113183:FAK-related nonkinase; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048051:p38 Mitogen-Activated Protein Kinases; C529890:3',4'-dihydroxyflavonol