casein-kinase-ii and Graft-Occlusion--Vascular

Emerging data suggest that urokinase-type plasminogen activator (UPA), beyond its role in pericellular proteolysis, may also act as a mitogen. We investigated the function of endogenous UPA in mediating the mitogenic effects of platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) on human vascular smooth muscle cells (SMC). Growth-arrested SMC constitutively expressed UPA, but UPA expression and secretion increased several times upon stimulation with either PDGF or bFGF. Inhibition of endogenous UPA with a polyclonal antibody significantly reduced DNA synthesis and proliferation of PDGF or bFGF stimulated SMC, this effect already being evident when the cells entered S-phase. The proliferative activity of endogenous UPA was dependent on a functional catalytic domain as demonstrated by inhibition experiments with a specific monoclonal antibody (394OA) and p-aminobenzamidine, respectively. In contrast, neither plasmin generation nor binding of UPA to its receptor (CD87) were required for UPA-mediated mitogenic effects. The results demonstrate that endogenous UPA is not only overexpressed in SMC upon stimulation with PDGF/bFGF, but also mediates the mitogenic activity of the growth factors in a catalytic-domain-dependent manner. Specific inhibition of this UPA domain may represent an attractive target for pharmacological interventions in atherogenesis and restenosis after angioplasty.

Topics: Arteriosclerosis; Casein Kinase II; Catalytic Domain; Cell Division; Cells, Cultured; DNA; Dose-Response Relationship, Drug; Drug Administration Schedule; Enzyme Inhibitors; Fibrinolysin; Fibroblast Growth Factor 2; Graft Occlusion, Vascular; Humans; Hypertrophy; Muscle, Smooth, Vascular; Platelet-Derived Growth Factor; Protein Serine-Threonine Kinases; Receptors, Cell Surface; Receptors, Urokinase Plasminogen Activator; Up-Regulation; Urokinase-Type Plasminogen Activator