The expression of monocyte adhesion molecules, such as VCAM-1 (vascular cell adhesion molecule-1) and E-selectin, on the surface of the endothelium is an important step in the initiation and progression of atherosclerotic lesions. We hypothesized that the inhibition of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase in endothelial cells could influence the expression of VCAM-1 and E-selectin. Using cultured human umbilical vein endothelial cells, we found that mevastatin (0.1–1μM) significantly reduced the expression of VCAM-1 protein in cells activated by tumour necrosis factor-α (TNF-α) for 7h. In contrast, TNF-α-induced E-selectin protein expression was augmented after mevastatin treatment. Mevastatin inhibited the mRNA expression of both VCAM-1 and E-selectin in TNF-α-stimulated endothelial cells. The activity of the transcription factor nuclear factor-κB, which is known to regulate the transcription of VCAM-1 and E-selectin, was significantly reduced after incubation with mevastatin. Analysis of the time-dependent variation in the TNF-α-induced expression of E-selectin, and estimation of the rate of surface disappearance of E-selectin together with measurement of the amounts of E-selectin molecules secreted, indicated that mevastatin inhibited the surface removal of E-selectin. This is compatible with the observed increase in E-selectin expression after statin treatment. All observed effects of mevastatin were reversed by mevalonate, the product of the HMG-CoA reductase reaction. In conclusion, inhibition of HMG-CoA reductase in endothelial cells attenuates VCAM-1 expression, but increases E-selectin expression, after cytokine induction. These diverse effects are associated with changes in the transcriptional regulation of the two adhesion molecule genes and modulation of the surface removal of E-selectin.
Abbreviations used: DMEM, Dulbecco's modified Eagle's medium; EMSA, electrophoretic mobility shift assay; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; HMG-CoA, hydroxymethylglutaryl-CoA; HRP, horseradish peroxidase; IL-1β, interleukin-1β; NF-κB, nuclear factor-κB; TMB, tetramethylbenzidine; TNF-α, tumour necrosis factor-α; VCAM-1, vascular cell adhesion molecule-1.
- The Biochemical Society, London ©2001