Involvement of MMP-2 and ADAM-12 in Thrombin-induced rat’ VSMCs proliferation
Katarina Smiljanic
Vinca Institute, University of Belgrade, Department for Molecular Genetics and Radiobiology, P.O. Box 522, Belgrade, Serbia
Abstract:
Thrombin (Thr) is involved in abnormal proliferation of vascular smooth muscle cells (VSMCs) associated with atherosclerosis and hypertension. Thr stimulation results in extracellular signal-regulated kinase (ERK1/2) activation through transactivation of the epidermal growth factor receptor (EGFR). Heparin-binding EGF-like growth factor (HB-EGF) and matrix metalloproteinases (MMPs) have also been detected in VSMCs and shown to be regulated by Thr. In this study, we investigated the role of HB-EGF and MMPs in Thr-mediated mitogenic action in rat VSMCs. Incubation of rat VSMCs with Thr (1 U/ml) for 5 minutes resulted in significant increase of ERK1/2, EGFR phosphorylation by 7.6-fold, 5.9-fold (p<0.001) and DNA synthesis by 3.8-fold (p<0.001), respectively. Pretreatments for 30 minutes with 10 M KB-R7785, specific ADAM-12 inhibitor or 10 M specific MMP-2 inhibitor or10 M anti-HB-EGF antibody, significantly reduced Thr-stimulated EGFR and ERK1/2 phosphorylation by 48 %, 48 % and 63 %, and by 25 %, 25 % and 41 %, respectively, and also reduced Thr-induced VSMC’s proliferation by 23 %, 45 % and 38 %, respectively. The results showed that Thr-induced DNA synthesis correlates with ERK1/2 activation rather than EGFR activation. Furthermore, these results suggest Thr acts through EGFR and ERK1/2 signaling pathways partially via MMP-2 and ADAM-12 to up-regulate VSMC’s proliferation.
