The secretome of endothelial cell: a tool for the study of the pleiotropic effects of statins

The clinical benefits of 3-hydroxy-3-methyl-3-glutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are strongly related to their low density lipoprotein-cholesterol lowering properties. However, because mevalonic acid, the product of HMG-CoA reductase reaction, is the precursor not only of cholesterol but also of nonsteroidal isoprenoid compounds, the inhibition of HMG-CoA reductase may result in pleiotropic effects. Indeed, a variety of experimental data indicates that statins can interfere with major events involved in the formation of atherosclerotic lesions, independent of their hypocholesterolemic properties, although these effects have not been fully elucidated. In this respect, the application of a global proteomic approach to determine the effect of statins on the proteins released, “secretome”, by endothelial cells could help to understand novel mechanisms by which statins promote some of their beneficial effects. Two methods were applied to the identification and quantification of proteins differentially regulated by statins: a “gel based method” employing 2-DE, which can offer the additional advantage to distinguish between proteins isoforms as well as different post-translationally modified forms of the same proteins, and a “gel-free MS-based method” for “label-free” quantitation, which provided absolute quantitative profiling of proteins. The results coming from the application of both approaches were integrated, validated by biochemical assays, and allowed us to fully characterize the secretome of endothelial cells and to identify the drug-regulated proteins. In conclusion, secretomes are a rich source of new therapeutics and drug targets, and have the potential to become a major focus of drug discovery programs throughout the industry. Funding: EC, FP6, LIFESCIHEALTH-contract n° LSHM-CT-2007-037273-PROCARDIS