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

Joo, Seung Jae; Cha, Tae Joon; Lee, Jae Woo

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 alphavbeta5 (92% inhibition), but was only slightly inhibited by LM609, a blocking mAb to integrin alphavbeta3 (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 alpha5beta1 (75% inhibition), but was not affected by c7E3, a blocking mAb to integrin beta3. 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 alphavbeta5 or JBS5.
CONCLUSION
These results indicate the different roles of integrins on vascular smooth muscle cells after ADP stimulation; the integrins alphavbeta5 and alpha5beta1 for adhesion, and the integrin alphavbeta3 for proliferation.