Effects of cerivastatin on human arterial smooth muscle cell growth and extracellular matrix expression at varying glucose and low-density lipoprotein levels.

Abstract

Statins exert pleiotropic effects on several other cellular functions besides lipid-lowering. Previously, it was found that cerivastatin is a very potent inhibitor of human arterial smooth muscle cell (haSMC) growth. However, because increased extracellular matrix (ECM) synthesis also accounts mainly for intimal plaque formation, the effects of cerivastatin on ECM expression was examined in this study. Furthermore, the influence of varying glucose and low-density lipoprotein (LDL) levels on cerivastatin-treated haSMCs was analyzed to mimic the conditions in patients with diabetes or hypercholesterolemia. The haSMCs were treated with 0.001-5.0 microM cerivastatin in the presence of 5.5-18.9 m glucose and 10-1000 microg/ml LDL. After 3 days, the messenger RNA (mRNA) expression of eight ECM proteins was analyzed and, after 7 days, mitotic and mitochondrial activities and thrombospondin (TSP)-1 protein expression were analyzed. TSP-1 and TSP-2 mRNA expression was inhibited highly significantly at cerivastatin doses >or=0.01 microM with maximums of 72% and 35%, respectively, at high glucose levels. The mRNA signals of the third glycoprotein fibronectin were not influenced. Furthermore, collagen-1 mRNA was inhibited highly significantly up to 71% and biglycan mRNA was similarly inhibited up to 45%. The mRNA expression of the matrix-stimulating transforming growth factor (TGF)-beta1 and matrix metalloproteinase (MMP)-2 was not altered significantly, whereas mRNA expression of the tissue inhibitor of metalloproteinase (TIMP)-2 was stimulated clearly up to 150%. Mevalonate, but not LDL replacement, reversed the effects. Immunofluorescence staining showed an unaltered TSP-1 pattern with cerivastatin doses up to 0.1 microM whereas higher doses impaired TSP-1 excretion. The effects of cerivastatin on haSMC growth and mRNA expression of the eight ECM components were not diminished by the increase in LDL and glucose levels. Since accelerated SMC growth and ECM formation contribute mainly to intimal thickening, cerivastatin may be protective against the development of atherosclerotic and restenotic lesions by its direct cellular effects. Increased LDL and glucose levels, as in diabetes, do not mitigate the beneficial effects of cerivastatin on cell growth and ECM formation in vitro.