geranylgeranyl-pyrophosphate and Arteriosclerosis

Cerivastatin is an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase. It inhibits the biosynthesis of cholesterol and its precursors: farnesyl pyrophosphate and geranylgeranyl pyrophosphate (GGPP), which are involved in Ras and RhoA cell signaling, respectively. Statins induce greater protection against vascular risk than that expected by cholesterol reduction. Therefore, cerivastatin could protect plaque against rupture, an important cause of ischemic events. In this study, the effect of cerivastatin was tested on angiogenesis because it participates in plaque progression and plaque destabilization. Cerivastatin inhibits in vitro the microvascular endothelial cell proliferation induced by growth factors, whereas it has no effect on unstimulated cells. This growth arrest occurs at the G(1)/S phase and is related to the increase of the cyclin-dependent kinase inhibitor p21(Waf1/Cip1). These effects are reversed by GGPP, suggesting that the inhibitory effect of cerivastatin is related to RhoA inactivation. This mechanism was confirmed by RhoA delocalization from cell membrane to cytoplasm and actin fiber depolymerization, which are also prevented by GGPP. It was also shown that RhoA-dependent inhibition of cell proliferation is mediated by the inhibition of focal adhesion kinase and Akt activations. Moreover, cerivastatin inhibits in vivo angiogenesis in matrigel and chick chorioallantoic membrane models. These results demonstrate the antiangiogenic activity of statins and suggest that it may contribute to their therapeutic benefits in the progression and acute manifestations of atherosclerosis.

Topics: Arteriosclerosis; Cell Division; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Endothelium, Vascular; G1 Phase; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Microcirculation; Neovascularization, Pathologic; Polyisoprenyl Phosphates; Pyridines; rhoA GTP-Binding Protein; Sesquiterpenes; Signal Transduction

Increased production of plasminogen activator inhibitor-1 (PAI-1) in plaques plays a role in the pathogenesis of atherosclerosis. This study was conducted to investigate the effect of blockade of Rho/Rho-kinase signaling on the synthesis of PAI-1 in cultured human peripheral blood monocytes. HMG-CoA reductase inhibitors (statins) and inhibitors of Rho and Rho-kinase were added to monocyte cultures. The levels of PAI antigen and mRNA were determined by Western blotting and RT-PCR, respectively, and PAI-1 expression was assessed by immunohistochemistry. We performed pull-down assays to determine the activity of Rho by measuring the GTP-bound form of Rho A. In unstimulated and lipopolysaccharide (LPS)-stimulated cultured monocytes, statins reduced the levels of PAI-1 antigen and mRNA. The suppressive effects of statins on PAI-1 synthesis were reversed by geranylgeranylpyrophosphate (GGPP) and were mimicked by C3 exoenzyme. Immunohistochemistry confirmed the role of lipid modification by GGPP in suppressive effect of statins in PAI-1 synthesis. Pull-down assays demonstrated that statins decreased the levels of the GTP-bound form of Rho A. Our findings suggest that statins decrease the activity of Rho by inhibiting geranylgeranylation. Moreover, Rho-kinase inhibitors, Y-27632 and fasudil, suppressed the synthesis of PAI-1 in this culture system. We show that inhibition of Rho/Rho-kinase signaling downregulates the synthesis of PAI-1 in human monocytes.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; ADP Ribose Transferases; Amides; Arteriosclerosis; Base Sequence; Botulinum Toxins; Cells, Cultured; Enzyme Inhibitors; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Intracellular Signaling Peptides and Proteins; Monocytes; Plasminogen Activator Inhibitor 1; Polyisoprenyl Phosphates; Pravastatin; Protein Prenylation; Protein Serine-Threonine Kinases; Pyridines; rho GTP-Binding Proteins; rho-Associated Kinases; RNA, Messenger; Signal Transduction

Topics: Arteriosclerosis; Caveolin 1; Caveolins; Cell Division; Cholesterol; Cysteine Proteinase Inhibitors; Endothelium, Vascular; GTP-Binding Proteins; Humans; Hydroxymethylglutaryl CoA Reductases; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypercholesterolemia; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Polyisoprenyl Phosphates; Sesquiterpenes; Signal Transduction; Superoxides