Integrins Mediating Adhesion and Proliferation of ADP-stimulated Vascular Smooth Muscle Cells

Abstract

Background and Objectives:Adenosine diphosphate (ADP), which is usually secreted from activated platelets, may activate integrins on vascular smooth muscle cells, resulting in adhesion and proliferation. Integrins, mediating the ADP-stimulated adhesion and proliferation of vascular smooth muscle cells, was investigated in this study. Materials and Methods:Prothrombin (PT) and bone sialoprotein (BSP) were used as activation-dependent ligands in an adhesion assay. The adhesion of human aortic smooth muscle cells (HASMC) were measured after ADP stimulation, using ligand-coated 24-well plates. The 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay was used to evaluate the ADP-stimulated proliferation of the HASMC. Results:ADP activated the HASMC to increase their adhesion to the PT or BSP, and their proliferation in a dose-dependent manner. The adhesion of the ADP-stimulated HASMC to the PT was completely blocked by P5H9, a blocking monoclonal Ab (mAb) to integrin αvβ5 (92% inhibition), but was only slightly inhibited by LM609, a blocking mAb to integrin αvβ3 (30% inhibition). The adhesion of the ADP-stimulated HASMC to the BSP was partially inhibited by both P5H9 (46% inhibition) and JBS5, a blocking mAb to integrin α5β1 (75% inhibition), but was not affected by c7E3, a blocking mAb to integrin β3. The ADP-stimulated proliferation of the HASMC was inhibited by both c7E3 and LM609 (98% and 93% inhibition, respectively), but not by either P1F5, a blocking mAb to integrin αvβ5 or JBS5. Conclusion:These results indicate the different roles of integrins on vascular smooth muscle cells after ADP stimulation;the integrins αvβ5 and α5β1 for adhesion, and the integrin αvβ3 for proliferation. (Korean Circulation J 2003;33 (5):409-419)