Probucol Protects Against Smooth Muscle Cell Proliferation by Upregulating Heme Oxygenase-1

Abstract

Background-Evidence suggests that induction of heme oxygenase-1 (HO-1) inhibits proliferation of vascular smooth muscle cells and intimal thickening after arterial injury, and therapeutic molecules induce HO-1. Probucol is the only oral drug that inhibits restenosis in humans and intimal thickening in animals, although its underlying mechanism remains unclear. Methods and Results-Aortas were harvested from New Zealand White rabbits fed normal or 0.75% (wt/wt) probucol-fortified chow, with or without endothelial denudation of the abdominal aorta on day 21, and analyzed for heme oxygenase and apoptosis. Uninjured aortas were harvested on day 21 and balloon-injured aortas on days 22 and 25. Probucol significantly increased mRNA of HO-1 assessed by real-time PCR and HO activity in aortas at all time points. Probucol also enhanced apoptosis of medial cells in the injured aorta, as evidenced by the TUNEL assay. Furthermore, probucol (100 mol/L) increased HO-1 mRNA and HO activity when added to rabbit aortic smooth muscle cells (RASMCs) cultured in serum-free medium for 24 hours. Induction of HO-1 mRNA was inhibited by actinomycin D and was associated with inhibition of RASMC proliferation. This probucol-induced increase in HO-1 mRNA and inhibition of RASMC proliferation was prevented by the HO inhibitor Sn(IV) protoporphyrin or transfection with small interference RNA (siRNA) to knockdown HO-1, but not by inactive Cu(II) protoporphyrin or scrambled siRNA. Conclusions-Probucol induces HO-1, and this contributes to the inhibition of vascular SMC proliferation. This novel finding may explain how probucol inhibits restenosis and highlights HO-1 as a target for therapeutic intervention against occlusive vascular disease.

Processes Involved in the Site-Specific Effect of Probucol on Atherosclerosis in Apolipoprotein E Gene Knockout Mice

“…32 We are presently investigating whether the apparent antiinflammatory action of probucol is related to its ability to induce heme oxygenase-1. 17,18,33 Unexpectedly, we observed the extent of probucol metabolism to be significantly increased in the aorta compared with the sinus (Figure 4), suggesting that some of the differences in action at the sinus versus descending aorta may be related to probucol metabolism. We do not know at present whether this relates to the previously reported antiinflammatory activity of probucol, ie, inhibition of lipopolysaccharideinduced secretion of interleukin-1 by macrophages.…”

“…15,16 It also prevents intimal thickening after balloon injury independent of cholesterol-lowering and inhibition of lipoprotein lipid oxidation, and instead promotes functional re-endothelialization and inhibits vascular smooth muscle cell proliferation via induction of heme oxygenase-1. 17,18 Strikingly, in apolipoprotein E-deficient (apoE Ϫ/Ϫ ) mice, probucol increases lesion size at the aortic sinus 19 while at the same time it strongly inhibits atherosclerosis in the descending aorta. 6 In the present study, we used this model to elucidate processes by which probucol exerts this sitespecific effect.…”

Basic Mechanisms of Oxidative Stress and Reactive Oxygen Species in Cardiovascular Injury

“…Similarly, in rabbits, adenoviral mediated gene transfer of SOD and catalase reduces restenosis after balloon angioplasty (Durand et al 2005). Probucol, a lipid lowering agent with antioxidant properties, inhibits neointima formation in rabbits after balloon injury through heme oxygenase-1-dependent and -independent pathways (Deng et al 2004). Neointima formation in rabbits was shown to be driven by adventitial and endothelial Nox2-derived O 2 •− in collared arteries (Paravicini et al 2002).…”

Neferine inhibits angiotensin II-stimulated proliferation in vascular smooth muscle cells through heme oxygenase-1

“…Increased HO-1 expression reduces intimal thickening after arterial injury and attenuates atherosclerosis in apolipoprotein E deficient mice [8] . Moreover, increased activity of HO-1 inhibits proliferation of VSMCs [9][10][11] . Interestingly, it has recently been reported that HO-1 inhibits the proliferation of pancreatic stellate cells by repression of the ERK1/2 pathway [12] .…”