Statins as cellular antithrombotics.

In clinical trials, statins (vastatins) reduce cardiovascular disease with cholesterol reduction, but this relationship is unclear. We reasoned that (1) thrombin (IIa) is an underlying mediator of cardiovascular events, (2) IIa mediates cellular events through its primary receptor [protease-activated receptor-1 (PAR-1)], and (3) statins inhibit an isoprenoid-dependent event between PAR-1 activation and tissue factor upregulation leading to IIa generation. In the isoprenoid pathways, statins inhibit mevalonic acid synthesis prior to divergence of the cholesterol and other pathway branches, where the latter produce cell-regulating substances (e.g., ras proteins). Through PAR-1 in platelets and other cells, IIa stimulates G-protein-coupled mechanisms including ras proteins. We hypothesize that statins exhibit antithrombotic properties at the cellular level downregulatating IIa generation and that statins may constitute a novel class of antithrombotics.