e0519 Rapamycin suppress KrÜppel-Like Factor 2 expression: mechanism of endothelial dysfunction associated with drug-eluting stents

Objects Although rapamycin released from drug-eluting stents (DESs) affect the antithrombogenic function of endothelial cells, the exactly mechanisms underlying these effects are incompletely understood. We hypothesised that Krüppel-Like Factor 2 (KLF2), a novel and potent regulator of endothelial gene expression, might play an important role in stent thrombosis. Methods We observed the effect of rapamycin on expression of KLF2, endothelial NO synthase (eNOS), tissue-plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1) and tissue factor (TF) in Human Umbilical Vein Endothelial Cells (HUVECs). Then, with overexpression of KLF2, we mensurated the above mentioned mRNA and protein, respectively. The mRNA and protein were mensurated by RT-PCR and Western Blot Analysis. Furthermore, activation of KLF2 was evaluated by Electrophoretic Mobility Shift Assay (EMSA). Results Rapamycin made the expression and activation of KLF2 strongly reduce by 75.6% and 78.2% so as to induce long-term coronary endothelial dysfunction. In HUVECs, rapamycin made basal eNOS and t-PA decrease by 80% and 87.8%, while making basal PAI-1 and TF increase by 2.5 and 1.5-fold. Overexpression of KLF2 strongly induced eNOS and t-PA expression and reduced PAI-1 and TF expression, reversing protein above-mentioned near to normal state. Conclusions The data indicated that rapamycin strongly inhibited the expression of KLF2, meanwhile, reduced anticoagulants (eNOS and t-PA) and induced procoagulants (PAI-1 and TF). KLF2 played an important role in stent thrombosis owing to rapamycin-induced endothelial dysfunction, which might be a part of mechanism of stent thrombosis associated with DESs.