Induction of Tissue Factor Expression in Endothelial Cells by Basic Fibroblast Growth Factor and its Modulation by Fenofibric acid

Tissue factor (TF), expressed in endothelial cells (ECs) and enriched in human atherosclerotic lesions, acts as a critical initiator of blood coagulation in acute coronary syndrome. Basic fibroblast growth factor (bFGF) induces the proliferation and migration of ECs and plays a role in angiogenesis and restoration of endothelial integrity. As TF is implicated in angiogenesis, we studied the effect of bFGF on TF gene and protein expression. Methods: Human umbilical vein ECs (HUVECs) were exposed to bFGF. TF mRNA was assessed by Northern blot and TF protein was assessed by Western blot. TF promoter activity was assessed by transient transfection assay and transcription factor was identified by electro mobility shift assay.

bFGF increased TF mRNA and protein expression in HUVECs. Increased TF mRNA was attenuated by inhibition of extracellular signal-regulated kinase kinase in human ECV304 cells. Transient transfection assays of the human TF promoter-luciferase construct (-786/+121 bp) demonstrated that bFGF induced transcription was dependent on the elements within the -197 to -176 bp relative to the transcription start site of the human TF gene. This region contains NF-κB like binding site. Electro mobility shift assay showed that bFGF increased nuclear translocation or DNA binding of NF-κB transcription factor to TF promoter. Nucleotide substitution to disrupt NF-κB like site reduced bFGF stimulated promoter activity. Fenofibric acid, an agonist ligand for the peroxisome proliferator activated receptor-α, reduced basal and bFGF stimulated TF expression.

These results indicate that bFGF may increase TF production in ECs through activation of transcription at NF-κB binding site, and control coagulation in vessel walls. Fibrate can inhibit TF expression and therefore reduce the thrombogenecity of human atherosclerotic lesions.