Survivin: a novel regulator of intimal hyperplasia and vein graft remodeling

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Failure of vascular interventions, including angioplasty, stenting, and bypass surgery, frequently results from an exaggerated healing response in the vessel wall, leading to narrowing and occlusion. This process is characterized by the formation of intimal hyperplasia (IH), a lesion consisting primarily of smooth muscle cells (SMC) bearing a proliferative, synthetic, and de-differentiated phenotype. Recent evidence suggests that survivin (SW), a novel protein which regulates both apoptosis and proliferation, may be an important therapeutic target in disorders characterized by dysregulated growth, such as cancer and IH. In this translational research proposal we seek to validate SW as a molecular target in IH, most particularly in the context of vein graft failure. First we will investigate approaches to directly inhibit SW gene expression, in- vitro and in-vivo. The effects of SW knockdown on SMC phenotype and vein graft hyperplasia will be determined. In the second specific aim, we will explore the therapeutic relevance of the interaction between SW and heat shock protein 90 (HspQO), a molecular chaperone, using a peptide-based approach to disrupt this critical protein-protein interaction. Finally in the third aim we will investigate whether anti-SW molecular strategies may sensitize vascular SMC to the pro-apoptotic effects of statin drugs, potentially expanding the therapeutic utility of these atheroprotective drugs to extend the benefits of vascular interventions. Vein bypass surgery, currently employed in some 500,000 cases annually in the United States, is a critical life- or limb-sparing intervention for many patients afflicted with cardiovascular disease. Although often effective, vein bypass grafts are subject to a significant rate of failure over time (30- 50% within five years), leading directly to mortality, limb amputation and diminished quality of life. This proposal seeks to broaden the understanding of factors which are involved in vein graft failure, and will examine a novel approach to re- engineer bypass grafts that may be resistant to occlusion. These studies also have direct relevance for improving the long term results of other cardiovascular interventions such as percutaneous angioplasty and stenting, by providing new molecular approaches to control the vascular injury response.