Ginsenoside Rb3 Inhibits Angiotensin II‐Induced Vascular Smooth Muscle Cells Proliferation

Abstract: This study was designed to examine the effect of ginsenoside Rb₃ on angiotensin (Ang) II‐induced proliferation of cultured rat vascular smooth muscle cells (VSMCs). VSMCs proliferation was evaluated by [³H]Thymidine incorporation. The cell cycle was examined by flow cytometry. The expression of mRNA of proto‐oncogene c‐myc, c‐fos and c‐jun was observed by RT‐PCR. Ginsenoside Rb₃ had no effects on VSMCs proliferation in physiological condition. Ang II significantly increased the proliferation of VSMCs and the expression of mRNA of proto‐oncogene c‐myc, c‐fos and c‐jun. Ginsenoside Rb₃ markedly inhibited Ang II‐induced VSMCs proliferation. Concomitantly, ginsenoside Rb₃ decreased cell cycle progression from G₀/G₁ to S phase. Furthermore, ginsenoside Rb₃ significantly attenuated the expression of mRNA of proto‐oncogene c‐myc, c‐fos and c‐jun. This study showed that ginsenoside Rb₃ inhibited Ang II‐induced VSMCs proliferation, at least in part by inhibiting Ang II‐induced G₀/G₁ to S phase transition and attenuating the expression of mRNA of c‐fos, c‐jun and c‐myc. The findings may explain the beneficial effects of ginsenoside Rb₃ in cardiovascular diseases, and it will be useful to develop prevention and therapeutics of cardiovascular diseases.     

钩藤碱和异钩藤碱抑制血管紧张素Ⅱ诱导血管平滑肌细胞增殖及相关机制

目的探讨钩藤碱和异钩藤碱对血管紧张素Ⅱ诱导的血管平滑肌细胞增殖的抑制效应及相关机制。方法建立血管紧张素Ⅱ诱导血管平滑肌细胞增殖模型,通过四甲基偶氮唑盐比色法、流式细胞术和逆转录聚合酶链反应观察钩藤碱和异钩藤碱对其增殖活性、细胞周期、细胞膜AT1R蛋白表达、信号转导通路NF-κB和Stat3蛋白表达、原癌基因c-Myc和c-Fos蛋白表达与mRNA转录的影响。结果血管紧张素Ⅱ明显刺激血管平滑肌细胞增殖,钩藤碱和异钩藤碱呈剂量依赖性抑制血管紧张素Ⅱ诱导的血管平滑肌细胞增殖;在钩藤碱和异钩藤碱干预下,血管平滑肌细胞处于G0/G1期的细胞数明显增多,S期的细胞数明显减少,c-Myc、c-Fos、AT1R、NF-κB、Stat3的蛋白表达以及c-MycmRNA和c-FosmRNA转录也明显降低。结论钩藤碱和异钩藤碱对血管紧张素Ⅱ诱导血管平滑肌细胞增殖有明显抑制效应,其机制与阻滞血管平滑肌细胞G0/G1期向S期转化以及下调AT1R、NF-κB、Stat3、c-Myc、c-Fos蛋白的表达以及c-MycmR-NA和c-FosmRNA转录有关。     

Losartan Inhibits Vascular Smooth Muscle Cell Proliferation through Activation of AMP-Activated Protein Kinase

Losartan is a selective angiotensin II (Ang II) type 1 (AT₁) receptor antagonist which inhibits vascular smooth muscle cells (VSMCs) contraction and proliferation. We hypothesized that losartan may prevent cell proliferation by activating AMP-activated protein kinase (AMPK) in VSMCs. VSMCs were treated with various concentrations of losartan. AMPK activation was measured by Western blot analysis and cell proliferation was measured by MTT assay and flowcytometry. Losartan dose- and time-dependently increased the phosphorylation of AMPK and its downstream target, acetyl-CoA carboxylase (ACC) in VSMCs. Losartan also significantly decreased the Ang II- or 15% FBS-induced VSMC proliferation by inhibiting the expression of cell cycle associated proteins, such as p-Rb, cyclin D, and cyclin E. Compound C, a specific inhibitor of AMPK, or AMPK siRNA blocked the losartan-induced inhibition of cell proliferation and the G₀/G₁ cell cycle arrest. These data suggest that losartan-induced AMPK activation might attenuate Ang II-induced VSMC proliferation through the inhibition of cell cycle progression.     

Downregulation of Angiotensin II-Induced 12-Lipoxygenase Expression and Cell Proliferation in Vascular Smooth Muscle Cells from Spontaneously Hypertensive Rats by CCL5

Angiotensin II (Ang II) plays an important role in vascular hypertension. The role of the chemokine CCL5 on Ang II-induced activities in vascular smooth muscle cells (VSMCs) has not been studied. In this study, we elucidated the effect of CCL5 on Ang II-induced 12-lipoxygenase (LO) expression and cell proliferation in spontaneously hypertensive rats (SHR) VSMCs. CCL5 decreased Ang II-induced 12-LO mRNA expression and protein production, and it increased Ang II type 2 (AT₂) receptor expression in SHR VSMCs. The inhibitory effect of CCL5 on Ang II-induced 12-LO mRNA expression was mediated through the AT₂ receptor. Although treatment of CCL5 alone induced SHR VSMCs proliferation, CCL5 inhibited Ang II-induced VSMCs proliferation and PD123,319, an AT₂ receptor antagonist, blocked the inhibitory effect of CCL5 on Ang II-induced VSMCs proliferation. Phosphorylation of p38 was detected in VSMCs treated with Ang II or CCL5 alone. But, decrease of p38 phosphorylation was detected in VSMCs treated with Ang II and CCL5 simultaneously (Ang II/CCL5) and PD123,319 increased p38 phosphorylation in VSMCs treated with Ang II/CCL5. Therefore, these results suggest that the inhibitory effect of CCL5 on Ang II-induced VSMCs proliferation is mediated by the AT₂ receptor via p38 inactivation, and CCL5 may play a beneficial role in Ang II-induced vascular hypertension.     

香青兰总黄酮对血管紧张素Ⅱ诱导血管平滑肌细胞增殖与迁移的影响

目的:研究香青兰总黄酮对血管紧张素Ⅱ(AngⅡ)诱导的大鼠主动脉血管平滑肌细胞(VSMC)增殖与迁移的作用。方法:采用贴壁法培养大鼠胸主动脉平滑肌细胞,以Ang Ⅱ为诱导剂,建立VSMC细胞增殖的模型,分别应用质量浓度为10^-7 mol·L^-1 Ang Ⅱ以及Ang Ⅱ+不同浓度香青兰总黄酮组(25,50,100 mg·L^-1)作用24 h,并设空白对照组进行比较。采用MTT法检测细胞的增殖;transwell法检测细胞的迁移;免疫组化法检测细胞内增殖细胞核抗原(PCNA)的表达水平。结果:与对照组比较,Ang Ⅱ组能显著刺激大鼠VSMC的增殖和迁移,香青兰总黄酮不同剂量组联合Ang Ⅱ可在一定程度上抑制Ang Ⅱ诱导的VSMC增殖,迁移以及细胞内PCNA的表达,且呈现一定的剂量依赖关系趋势。结论:香青兰总黄酮具有抑制Ang Ⅱ诱导VSMC增殖与迁移的作用。     

ERK1/2 pathway is involved in the inhibitory effect of crocetin on angiotensin II-induced vascular smooth muscle cell proliferation

Angiotensin II (Ang II) induces vascular smooth muscle cells (VSMCs) proliferation, which plays an important role in the development and progression of atherosclerosis. Ang II-induced cellular events have been implicated, in part, in the activation of extracellular signal-regulated kinases 1/2 (ERK1/2). Crocetin is a natural carotenoid compound isolated from Gardenia jasminoids Ellis. In the present study, we investigated the effect of crocetin on the Ang II-induced VSMCs proliferation and ERK1/2 activation. 3-[4,5-dimethylthiazol-2-yl]-2,5-dephenyl tetrazolium bromide (MTT) and [3H]thymidine incorporation assay showed that the Ang II-induced VSMCs proliferation was inhibited significantly by crocetin. In-gel kinase assay indicated that Ang II elicited rapid and significant increase of ERK1/2 activity in VSMCs, which was suppressed by crocetin markedly. Western blotting analysis and cell-based enzyme-linked immunosorbent assay (ELISA) demonstrated that crocetin significantly inhibited the phosphorylation and activation of ERK1/2 induced by Ang II. Using the indirect immunofluorescent technique, we also found that crocetin inhibited nuclear translocation of activated ERK1/2 induced by Ang II. These findings suggest that the suppression by crocetin of the Ang II-induced VSMCs proliferation can be attributed, at least in part, to its inhibitory effect on ERK1/2 pathway.     

钩藤提取物抑制血管紧张素Ⅱ诱导血管成纤维细胞增殖及胶原合成的研究

目的探讨钩藤碱和异钩藤碱对血管紧张素Ⅱ(AngⅡ)诱导的血管成纤维细胞(VAF)增殖及胶原沉积的抑制效应及相关机制。方法建立AngⅡ诱导VAF增殖模型,通过四甲基偶氮唑盐比色法、扫描电镜技术、流式细胞术、天狼猩红染色法和逆转录聚合酶链反应等观察钩藤碱和异钩藤碱对其增殖活性、细胞形态、细胞周期、细胞凋亡率、细胞c-myc蛋白表达、细胞培养液中羟脯氨酸含量、细胞间胶原蛋白含量、细胞ColⅠmRNA和ColⅢmRNA的影响。结果AngⅡ刺激VAF增殖,钩藤碱和异钩藤碱抑制AngⅡ诱导VAF增殖;在钩藤碱和异钩藤碱作用下VAF处于G0/G1期的细胞数增多、S期的细胞数减少、细胞凋亡率增加、细胞c-myc蛋白表达降低、细胞培养液中羟脯氨酸含量降低、细胞间胶原表达降低、细胞ColⅠmRNA和ColⅢmRNA转录也降低。结论钩藤碱和异钩藤碱对AngⅡ诱导VAF增殖和胶原沉积有抑制效应,部分机制与其阻滞VAF G0/G1期向S期转化、诱导细胞凋亡、下调细胞c-myc蛋白表达和细胞ColⅠmRNA和ColⅢmRNA转录有关。     

Regulation of angiotensin II-Induced Krüppel-like factor 5 expression in vascular smooth muscle cells

Angiotensin (Ang) II plays a critical role in cardiovascular remodeling. Krüppel-like factor (KLF) 5 is a novel indicated mediator in Ang II-induced cardiovascular damage. However, the potential link between KLF5 and Ang II has not been well investigated. In this study, we showed that in growth-arrested vascular smooth muscle cells (VSMCs), Ang II induced cell proliferation, KLF5 mRNA and protein expression in a dose- and time-dependent fashion, whereas KLF5 mRNA stability was not affected. The AT1 antagonist losartan significantly blocked Ang II-induced KLF5 expression. Furthermore, several intracellular signals elicited by Ang II were involved in KLF5 gene upregulation, including phosphate tyrosine kinase, mitogen-activated protein kinases and reactive oxygen species. These data, for the first time, revealed the involvements of some intracellular signals in the regulation of KLF5 expression in response to Ang II in VSMCs and showed the possible role of KLF5 in Ang II-induced cell proliferation in VSMCs.     

Effects and mechanisms of total Panax notoginseng saponins on proliferation of vascular smooth muscle cells with plasma pharmacology method

Objectives Total Panax notoginseng saponin (TPNS) is extracted from Panax notoginseng. Our previous studies suggested that TPNS could inhibit intimal hyperplasia. This study discussed the impact of TPNS on the proliferation of vascular smooth muscle cells (VSMCs) and revealed the associated mechanisms through cell cycle‐related factors and extracellular regulated protein kinase (ERK) signal transduction pathway. Methods A VSMC proliferation model induced by platelet‐derived growth factor (PDGF) was established to observe the effects of rat drug‐containing plasma on VSMC proliferation. Key findings After being stimulated by PDGF, the proliferating cell nuclear antigen (PCNA) and c‐fos content increased, while up‐regulation of cyclinD1, cyclin‐dependent kinase‐4 (CDK4) and down‐regulation of p21 protein were observed. These changes were inhibited by atorvastatin and TSPN drug‐containing plasma, and the inhibitive activity in both groups was not significant. Furthermore, both atorvastatin and TSPN could obviously inhibit the activation of PDGF‐induced P‐ERK1/2 and increase the content of MKP‐1, there were also no significant differences. Conclusions These results suggested that atorvastatin and TPNS could inhibit VSMC proliferation by inhibiting the activation of ERK signalling pathway.     

一氧化氮部分介导吡格列酮抑制培养兔胸主动脉平滑肌细胞增殖

目的:观察吡格列酮(PIO)对高糖高胰岛素诱导兔胸主动脉平滑肌细胞(VSMCs)增殖的影响及其与一氧化氮(NO)的关系.方法:模拟胰岛素抵抗 (IR)状态培养VSMCs,四甲基氮唑盐(MTT)比色法测定细胞增殖,试剂盒分别检测细胞液中NO含量及细胞总一氧化氮合酶(NOS)、诱导型一氧化氮合酶(iNOS)活性.结果:PIO干预后,正常培养组和模拟IR培养组VSMCs含MTT溶解物的吸光值(A490)均低于各自对照组(P＜0.01).PIO显著增加VSMCs总NOS活性、iNOS活性以及NO含量(P＜0.01).PIO上述作用在模拟IR培养时更强,均可被NOS抑制剂L-NAME部分阻断.结论:在正常或模拟IR培养时,PIO抑制VSMCs增殖的作用部分通过NO介导.     

硝苯地平抑制自发性高血压大鼠血管平滑肌细胞内肌醇磷脂量的增加

目的：观察硝苯地平对自发性高血压大鼠（ＳＨＲ）的动脉血管平滑肌细胞（ＶＳＭＣｓ）增殖、ｃ－ｆｏｓ原癌基因表达和细胞内肌醇磷脂含量的影响，以进一步阐明硝苯地平的抗高血压作用机制。方法：以ＭＴＴ法、斑点印迹杂交和细胞内肌醇磷脂含量测定方法与对照组比较硝苯地平对细胞的影响。结果：硝苯地平是ＶＳＭＣｓ异常增殖的有效抑制剂，并能明显阻止ＳＨＲ的ＶＳＭＣｓ内ｃ－ｆｏｓ过度表达；研究也显示，硝苯地平显著地减小细胞内肌醇磷脂的过量增加。结论：硝苯地平能抑制ＳＨＲ的ＶＳＭＣｓ的ｃ－ｆｏｓ过度表达和细胞异常增殖，而这一作用可能与其阻止细胞内肌醇磷脂的过量增加有关。     

Osteopontin is required for angiotensin II-induced migration of vascular smooth muscle cells

Migration and proliferation of vascular smooth muscle cells (VSMCs) play a prominent role in the development of atherosclerotic plaques and restenosis lesions. Angiotensin II (Ang-II) is typically associated with excessive proliferation and migration of VSMCs and vascular remodeling. High levels of osteopontin (OPN) mRNA and protein were reported in human atherosclerotic plaque from the aorta, carotid and coronary arteries. However whether OPN plays a role in VSMCs migration induced by Ang-II is unknown. Here we show that, in primary cultured rat VSMCs, Ang-II exhibits chemotactic effect on cultured VSMCs and induces OPN expression dose-dependently. With a lentiviral shRNA specifically targeting OPN and transwell migration assay, we find that blockade of OPN with shRNA inhibits Ang-II-induced MMP9 upregulation and VSMCs migration. Our results demonstrated that OPN is required for Ang-II to induce VSMCs migration and suggested OPN as a potential target in preventing atherosclerotic development.     

Cardamonin inhibits angiotensin II-induced vascular smooth muscle cell proliferation and migration by downregulating p38 MAPK,Akt, and ERK phosphorylation

Cardamonin is a chalconoid isolated from various herbs, such as Alpinia katsumadai and Carya cathayensis Sarg. This study examined the effect of cardamonin on angiotensin II (Ang II)-induced proliferation and migration in rat vascular smooth muscle cells (VSMCs) as well as its underlying mechanisms. The results showed that cardamonin significantly inhibited Ang II-induced proliferation and migration in rat VSMCs in a concentration-dependent manner. Moreover, cardamonin suppressed Ang II-induced phosphorylation of p38 MAPK, Akt, and extracellular regulated protein kinase (ERK). These findings indicate that the downregulation of p38 MAPK, Akt, and ERK phosphorylation might be, at least in part, involved in cardamonin-suppressed proliferation and migration induced by Ang II in rat VSMCs. As proliferation and migration of VSMCs play critical roles in the pathogenesis of atherosclerosis, cardamonin might be a potential candidate for atherosclerosis treatment.     

Effect of berberine on PPARα-NO signalling pathway in vascular smooth muscle cell proliferation induced by angiotensin IV

Context: The available treatments for the abnormal proliferation of vascular smooth muscle cells (VSMCs) are still dismal. Berberine has been demonstrated to possess extensive medicine activity, yet relatively little is known about its effect on VSMCs proliferation. Many studies showed that PPARα and NO participated in the process of VSMCs proliferation.

Objective: To evaluate the effect of berberine and its possible influence on PPARα-NO pathway in angiotensin IV-stimulated VSMCs.

Materials and methods: The primary VSMCs were cultured with the tissue explants method, and the proliferation was characterized by MTT and protein content. Protein and mRNA expression were measured by Western blot and real-time RT-PCR, respectively. NO synthase (NOS) activity was measured using a spectrophotometric assay, and NO concentration was measured using the Griess assay.

Results: Angiotensin IV (0.1?nmol/L)-induced VSMCs proliferation was evidenced by increasing the optical density at A₄₉₀ and total protein content (p?p?p?p?p?p?Discussion and conclusion: The results support the therapeutic effects of berberine on angiotensin IV-induced proliferation in cultured VSMCs at least partially through targeting the PPARα-NO signalling pathway.     

Nitrosonifedipine ameliorates angiotensin II-induced vascular remodeling via antioxidative effects

Nifedipine is unstable under light and decomposes to a stable nitroso analog, nitrosonifedipine (NO-NIF). The ability of NO-NIF to block calcium channels is quite weak compared with that of nifedipine. Recently, we have demonstrated that NO-NIF reacts with unsaturated fatty acid leading to generate NO-NIF radical, which acquires radical scavenging activity. However, the effects of NO-NIF on the pathogenesis related with oxidative stress, such as atherosclerosis and hypertension, are unclear. In this study, we investigated the effects of NO-NIF on angiotensin II (Ang II)-induced vascular remodeling. Ang II-induced thickening and fibrosis of aorta were inhibited by NO-NIF in mice. NO-NIF decreased reactive oxygen species (ROS) in the aorta and urinary 8-hydroxy-20-deoxyguanosine. Ang II-stimulated mRNA expressions of p22^phox, CD68, F4/80, monocyte chemoattractant protein-1, and collagen I in the aorta were inhibited by NO-NIF. Moreover, NO-NIF inhibited Ang II-induced cell migration and proliferation of vascular smooth muscle cells (VSMCs). NO-NIF reduced Ang II-induced ROS to the control level detected by dihydroethidium staining and lucigenin chemiluminescence assay in VSMCs. NO-NIF suppressed phosphorylations of Akt and epidermal growth factor receptor induced by Ang II. However, NO-NIF had no effects on intracellular Ca²⁺ increase and protein kinase C-δ phosphorylation induced by Ang II in VSMCs. The electron paramagnetic resonance spectra indicated the continuous generation of NO-NIF radical of reaction with cultured VSMCs. These findings suggest that NO-NIF improves Ang II-induced vascular remodeling via the attenuation of oxidative stress.     

5,8-Dimethoxy-2-Nonylamino-Naphthalene-1,4-Dione Inhibits Vascular Smooth Muscle Cell Proliferation by Blocking Autophosphorylation of PDGF-Receptor β

As the abnormal proliferation of vascular smooth muscle cells (VSMCs) plays a critical role in the development of atherosclerosis and vascular restenosis, a candidate drug with antiproliferative properties is needed. We investigated the antiproliferative action and underlying mechanism of a newly synthesized naphthoquinone derivative, 5,8-dimethoxy-2-nonylamino-naphthalene-1,4-dione (2-nonylamino-DMNQ), using VSMCs treated with platelet-derived growth factor (PDGF). 2-Nonylamino-DMNQ inhibited proliferation and cell number of VSMCs induced by PDGF, but not epidermal growth factor (EGF), in a concentration-dependent manner without any cytotoxicity. This derivative suppressed PDGF-induced [³H]-thymidine incorporation, cell cycle progression from G₀/G₁ to S phase, and the phosphorylation of phosphor-retinoblastoma protein (pRb) as well as the expression of cyclin E/D, cyclin-dependent kinase (CDK) 2/4, and proliferating cell nuclear antigen (PCNA). Importantly, 2-nonylamino-DMNQ inhibited the phosphorylation of PDGF receptorβ(PDGF-Rβ) enhanced by PDGF at Tyr⁵⁷⁹, Tyr⁷¹⁶, Tyr⁷⁵¹, and Tyr¹⁰²¹ residues. Subsequently, 2-nonylamino-DMNQ inhibited PDGF-induced phosphorylation of STAT3, ERK1/2, Akt, and PLCγ1. Therefore, our results indicate that 2-nonylamino-DMNQ inhibits PDGF-induced VSMC proliferation by blocking PDGF-Rβ autophosphorylation, and subsequently PDGF-Rβ-mediated downstream signaling pathways.     

Murrayafoline A Induces a G0/G1-Phase Arrest in Platelet-Derived Growth Factor-Stimulated Vascular Smooth Muscle Cells

The increased potential for vascular smooth muscle cell (VSMC) growth is a key abnormality in the development of atherosclerosis and post-angioplasty restenosis. Abnormally high activity of platelet-derived growth factor (PDGF) is believed to play a central role in the etiology of these pathophysiological situations. Here, we investigated the anti-proliferative effects and possible mechanism(s) of murrayafoline A, a carbazole alkaloid isolated from Glycosmis stenocarpa Guillamin (Rutaceae), on PDGF-BB-stimulated VSMCs. Murrayafoline A inhibited the PDGF-BB-stimulated proliferation of VSMCs in a concentration-dependent manner, as measured using a non-radioactive colorimetric WST-1 assay and direct cell counting. Furthermore, murrayafoline A suppressed the PDGF-BB-stimulated progression through G₀/G₁ to S phase of the cell cycle, as measured by [³H]-thymidine incorporation assay and cell cycle progression analysis. This anti-proliferative action of murrayafoline A, arresting cell cycle progression at G₀/G₁ phase in PDGF-BB-stimulated VSMCs, was mediated via down-regulation of the expression of cyclin D1, cyclin E, cyclin-dependent kinase (CDK)2, CDK4, and proliferating cell nuclear antigen (PCNA), and the phosphorylation of retinoblastoma protein (pRb). These results indicate that murrayafoline A may be useful in preventing the progression of vascular complications such as restenosis after percutaneous transluminal coronary angioplasty and atherosclerosis.     

萘哌地尔衍生物YMⅢ抗AngⅡ诱导SHR血管平滑肌细胞增殖的作用

目的观察萘哌地尔衍生物YMⅢ对血管紧张Ⅱ(AngⅡ)诱导的自发性高血压大鼠(SHR)血管平滑肌细胞(VSMC)增殖的影响,并初探其作用机制。方法以组织块贴壁法培养SHR VSMC,应用MTT比色法、3[H]-TdR参入法、流式细胞技术、电镜技术和real time RT-PCR分别观察VSMC在AngⅡ刺激下的细胞增殖、DNA合成、细胞周期、细胞超微结构和Agt、c-myc基因表达的变化,及观察YMⅢ对上述指标的影响。结果 AngⅡ1μmol.L-1明显促进VSMC增殖和DNA合成;而YMⅢ0.01、0.05、0.10μmol.L-1可呈浓度依赖性地抑制AngⅡ所致VSMC增殖活性、DNA合成、细胞周期增殖指数的升高,改善细胞超微结构,并使AngⅡ升高的Agt、c-myc mRNA表达下调。结论 YMⅢ可明显抑制AngⅡ诱导的SHR VSMC增殖,作用机制可能与其抑制Agt、c-myc mRNA表达,从而抑制细胞DNA合成和细胞周期的进展有关。     

Inhibitory effect of fenofibrate on neointima hyperplasia via G(0)/G(1) arrest of cell proliferation

We have previously reported that fenofibrate displayed a potent antithrombotic effect by the inhibition of platelet aggregation. The present study was designed to investigate the effects of fenofibrate on the neointimal hyperplasia and its possible molecular mechanism. Neointimal hyperplasia was measured in balloon-inflated–induced vascular injury model of male Sprague–Dawley rats and cell proliferation was measured in primary cultured rat aortic vascular smooth muscle cells (VSMCs). Fenofibrate-treated group showed a significant reduction in neointimal formation (0.07 ± 0.04 mm²) from the control (0.13 ± 0.04 mm²). Fenofibrate significantly inhibited platelet-derived growth factor (PDGF)-BB-induced cell counting and [³H]-thymidine incorporation into DNA. Fenofibrate suppressed the PDGF-BB-inducible progression through G₀/G₁ to S phase of cell cycle. Moreover, fenofibrate inhibited not only phosphorylation of retinoblastoma (Rb) protein and expression of cyclin D/E, CDK 2/4 and proliferating cell nuclear antigen (PCNA) proteins but also mitogen-activated protein kinase (MAPK) signaling pathways such as ERK 1/2, p38 and JNK phosphorylation. In conclusion, the present study demonstrates that fenofibrate significantly inhibits neointimal formation via G₀/G₁ arrest of PDGF-BB-induced cell proliferation in association with the inhibition of MAPK, which resulted in the downregulation of expressions of cyclin D/E, CDK 2/4 and PCNA proteins, suggesting that fenofibrate may be useful for individuals with a high risk of thrombotic or cardiovascular diseases.