The mTOR/AP-1/VEGF signaling pathway regulates vascular endothelial cell growth

Vascular restenosis is a common adverse event following percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). The atypical Ser/Thr protein kinase mammalian target of rapamycin (mTOR) plays an important role in cell differentiation and apoptosis. Vascular restenosis caused by excessive endothelial cell proliferation can be inhibited by local application of the mTOR inhibitor rapamycin (RAPA); however, RAPA can also suppress normal vascular endothelial cell growth by blocking mTOR/VEGF signaling, although the underlying mechanism is still unclear. Here, endogenous mTOR, AP-1, and VEGF were inhibited or overexpressed to investigate the mechanism underlying the effects of RAPA. Inhibition of AP-1 or mTOR with AP-1-siRNA or RAPA treatment respectively, decreased vascular endothelial cell proliferation, upregulation of AP-1 or mTOR increased cell proliferation, and VEGF overexpression increased, while RAPA-induced mTOR inhibition decreased vascular endothelial cell proliferation, the results indicate that combining mTOR downregulation and VEGF upregulation might both inhibit restenosis and maintain normal vascular endothelial cell growth after PCI or CABG, suggest the mTOR/AP-1/VEGF pathway might play a crucial role in regulating vascular endothelial cell growth.