Molecular mechanisms of the antiproliferative effect of beraprost, a prostacyclin agonist, in murine vascular smooth muscle cells

Abstract

Prostacyclin (PGI2) has been shown to inhibit proliferation in vascular smooth muscle cells. To clarify the underlying molecular mechanism, we investigated the vasoprotection of beraprost (a PGI2 agonist) both in vivo and in vitro. Beraprost eliminated increases in proliferation of rat aortic smooth muscle cells (RASMCs) by 12-O-tetradecanoylphorbol 13-acetate, and enhanced the peroxisome proliferator-activated receptor-delta (PPARdelta) and inducible nitric oxide synthetase (iNOS) expressions, which were associated with the antiproliferative action of beraprost according to inhibition experiments by [(3)H]thymidine incorporation. Additionally, elimination of iNOS activity by PPARdelta antagonists suggested that iNOS is the downstream target of PPARdelta. Furthermore, beraprost increased both consensus PPARdelta-responsive element (PPRE)-driven luciferase activity and the binding activity of the PPARdelta to the putative PPRE in the iNOS promoter; nevertheless, it was abolished by PPARdelta antagonists. Deletion of PPRE (-1,349/-1,330) in the iNOS promoter region (-1,359/+2) strongly reduced promoter-driven activity, representing a novel mechanism of iNOS induction by beraprost. Consistent with this, PPARdelta and the concomitant iNOS induction by beraprost were also evident in vivo. Beraprost-mediated protection in a murine model of balloon angioplasty was significantly attenuated by 13S-HODE, a PPARdelta antagonist. Taken together, the results suggest that the causal relationship between PPARdelta and iNOS contributes to the vasoprotective action of beraprost in RASMCs.

Inhibitory effect of D1-like and D3dopamine receptors on norepinephrine-induced proliferation in vascular smooth muscle cells

“…After the induction of quiescence in 96-well plastic culture dishes at the density of 1ϫ10 3 cells/well, the cells were incubated with the indicated drugs for 24 h. Subsequently, 20 l of MTT (2.5 g/l) were added to each well, and the incubation continued for an additional 4 h at 37°C. Thereafter, 150 l DMSO were added to each well, and an absorbance at 490 nm was read on a Microplate reader (model 680, Bio-Rad) (25,26). 3 H]thymidine (1 Ci/ml) was then added to the growth medium of each well 6 h before the measurements.…”

Molecular Mechanisms Regulating the Vascular Prostacyclin Pathways and Their Adaptation during Pregnancy and in the Newborn

“…PGI 2 /PPAR␦ signaling stimulates expression of inducible NO synthase and consequently inhibits VSMC proliferation (Lin et al, 2008). PGI 2 /PPAR␦ signaling can also mediate long-term effects on VSMCs similar to those independently mediated by PGI 2 /cAMP.…”

PPARδ-mediated p21/p27 induction via increased CREB-binding protein nuclear translocation in beraprost-induced antiproliferation of murine aortic smooth muscle cells

“…For instance, a potent and selective PPAR␦ agonist GW0742X was shown by Graham et al to reduce atherosclerosis in LDLR Ϫ/Ϫ mice (5). Furthermore, we previously linked the causal relationship of PPAR␦ and inducible nitric oxide synthase (iNOS) in reducing neointimal formation of the murine carotid artery with balloon injury (13). Those observations suggest an atheroprotective effect of PPAR␦ agonists in vivo.…”