Isothiazole dioxide derivative 6n inhibits vascular smooth muscle cell proliferation and protein farnesylation

Isothiazole dioxides have been shown to inhibit Trypanosoma brucei protein farnesyltransferase (PFTase) in isolated enzyme, but elicited only a minor effect on mammalian PFTase. In the present study we have evaluated the effect of 3-diethylamino-4-(4-methoxyphenyl)-isothiazole 1,1-dioxides with different substituents at C5, on rat PFTase and protein geranylgeranyltransferase-I (PGGTase-I) with the final aims to improve the potency against mammalian PFTase and to identify new compounds with antiproliferative properties. For these purposes, in vitro and cell culture models have been utilized. The results showed that isothiazole dioxides with C4–C5 double bond and sulfaryl substituted at the C5 position but none of the dihydro-derivatives, were able to inhibit in vitro PFTase in a concentration dependent manner (IC₅₀ ranging from 8.56 to 1015 μM). Among those, compound 6n (C5; methyl-S) displayed 500-fold higher inhibitory potency on PFTase than PGGTase-I. Compound 6n was shown to affect rat smooth muscle cell (SMC) proliferation at concentrations similar (IC₅₀ = 61.4 μM) to those required to inhibit [³H]-farnesol incorporation into cellular proteins (−44.1% at 100 μM). Finally, compound 6n interferes with rat SMC proliferation by blocking the progression of G0/G1 phase without inducing apoptosis, as assessed by [³H]-thymidine incorporation assay and flow cytometry analysis. Taken together, we described a new PFTase inhibitor containing the isothiazole dioxide moiety that affects mammalian protein farnesylation and SMC proliferation by inhibiting G0/G1 phase of the cell cycle.     

Ligustilide inhibits vascular smooth muscle cells proliferation

Proliferation and migration of vascular smooth muscle cells (VSMCs) are believed to develop atherosclerosis and venous bypass graft disease. Ligustilide is widely used to treat some pathological settings such as atherosclerosis and hypertension. The aim of this study was to examine the effect of ligustilide on VSMCs proliferation. The results show that ligustilide significantly inhibited VSMCs proliferation and cell cycle progression. Further analysis shows that ligustilide suppressed reactive oxygen species production and extracellular signal-related kinases (ERK), c-Jun N-terminal protein kinase (JNK), and p38 MAP kinase. Cells were treated with antioxidant, superoxide dismutase, catalase, and DPI, respectively, leading to repress ERK, JNK, and p38 activation. The inhibitors of mitogen activated protein kinase (MAPK), PD98059, SB203580, and Sp600125, inhibited cell proliferation. These findings suggest the antiproliferative effect of ligustilide was associated with the decrement of reactive oxygen species resulting in the suppression of MAPK pathway. Thus, ligustilide contribute to be the effective agent in preventing cardiovascular diseases.     

Ferulic acid inhibits vascular smooth muscle cell proliferation induced by angiotensin II

The aim of this study was to determine the effects of ferulic acid on the proliferation and molecular mechanism in cultured vascular smooth muscle cell (VSMC) induced by angiotensin II. It was shown that ferulic acid significantly inhibited angiotensin II-induced VSMC proliferation in a dose-dependent manner. Western blotting analyses suggest that the antiproliferative effect of ferulic acid was involved in the mitogen-activated protein kinases (MAPKs) pathway. While no effect on p38, ferulic acid markedly inactivated the extracellular signal-regulated kinases (ERK1/2) and c-Jun N-terminal kinases (JNK), indicating that the inhibition of ferulic acid on VSMC proliferation was associated with ERK1/2 and JNK rather than p38 pathway. On the expression of cell cycle regulatory proteins, ferulic acid elevated the protein content of p21(waf1/cip1), decreased expression of cyclin D1 and inhibited phosphorylation of retinoblastoma protein, suggesting that ferulic acid inhibited VSMC proliferation by regulating the cell progression from G1 to S phase. The inactivation of MAPKs and modulation of cell cycle proteins of ferulic acid may be of importance in preventing cardiovascular disease.     

Onychin inhibits proliferation of vascular smooth muscle cells by regulating cell cycle

AIM: To investigate the effects of onychin on the proliferation of cultured rat artery vascular smooth muscle cells (VSMCs) in the presence of 10% new-born calf serum (NCS). METHODS: Rat VSMCs were incubated with onychin 150 micromol/L or genistein 10 micromol/L in the presence of 10% NCS for 24 h. The proliferation of VSMCs was measured by cell counting and MTS/PMS colorimetric assays. Cell cycle progression was evaluated by flow cytometry. Retinoblastoma (Rb) phosphorylation, and expression of cyclin D1 and cyclin E were measured by Western blot assays. The tyrosine phosphorylation of ERK1/2 was examined by immunoprecipitation techniques using anti-phospho-tyrosine antibodies. RESULTS: The proliferation of VSMCs was accelerated significantly in the presence of 10% NCS. Onychin reduced the metabolic rate of MTS and the cell number of VSMCs in the presence of 10% NCS in a dose-dependent manner. Flow cytometry analysis revealed that the G1-phase fraction ratio in the onychin group was higher than that in the 10% NCS group (85.2% vs 70.0%, P<0.01), while the S-phase fraction ratio in the onychin group was lower than that in 10% NCS group (4.3% vs 16.4%, P<0.01). Western blot analysis showed that onychin inhibited Rb phosphorylation and reduced the expression of cyclin D1 and cyclin E. The effects of onychin on proliferation, the cell cycle and the expression of cyclins in VSMCs were similar to those of genistein, an inhibitor of tyrosine kinase. Furthermore immunoprecipitation studies showed that both onychin and genistein markedly inhibited the tyrosine phosphorylation of ERK1/2 induced by 10% NCS. CONCLUSION: Onychin inhibits the proliferation of VSMCs through G1 phase cell cycle arrest by decreasing the tyrosine phosphorylation of ERK1/2, and the expression of cyclin D1 and cyclin E, and sequentially inhibiting Rb phosphorylation.     

Phosphorylated troglitazone activates PPARgamma and inhibits vascular smooth muscle cell proliferation and proteoglycan synthesis

Phosphorylation of alpha-tocopherol produces an entity with enhanced antiatherogenic properties. Troglitazone, an alpha-tocopherol derivative of a 2,4-thiazolidinedione nucleus, is an antidiabetic agent that shows fatal idiosyncratic hepatotoxicity, a property not shared by later agents. We investigated the effects of phosphorylation of troglitazone (to yield "phosphoglitazone") on the biochemical pharmacologic properties of troglitazone. We investigated its ability to act as a PPARgamma agonist and to inhibit 2 atherogenic properties of vascular smooth muscle cells (vSMC)-proliferation and proteoglycan synthesis. PPARgamma activity was assessed in a transfection assay. Proliferation was assessed by [H]-thymidine incorporation and cell counting and proteoglycan synthesis by [S]-sulfate incorporation using human vSMCs stimulated with platelet-derived growth factor (PDGF; 50 ng/mL) and transforming growth factor (TGF)-beta (2 ng/mL). Phosphoglitazone was a full agonist for PPARgamma with a potency and efficacy similar to troglitazone. Phosphoglitazone also inhibited cell proliferation and proteoglycan synthesis with potency similar to troglitazone. We conclude that phosphorylation retains the pharmacologic activity of troglitazone while decreasing its lipophilicity and therefore potentially its toxicity. A phosphorylated derivative of a 2,4-thiazolidinedione warrants further investigation as a potential new therapeutic agent for the treatment of insulin resistance and Type 2 diabetes.     

Nifedipine inhibits vascular smooth muscle cell proliferation and reactive oxygen species production through AMP-activated protein kinase signaling pathway

The dihydropyridine calcium channel blocker nifedipine induces specific pharmacological effects by binding to L-type calcium channels, which results in a reduced calcium influx in vascular smooth muscle cells (VSMCs) and is currently employed in antihypertensive drug. Dihydropyridine calcium channel blocker is reported to reduce oxidative stress and exhibits anti-proliferative effect in VSMCs. VSMCs are useful in the study of atherosclerosis because they show cell proliferation and reactive oxygen species (ROS) production with growth factor. To determine the mechanisms involved in these effects, we investigated the influence of nifedipine-induced AMP-activated protein kinase (AMPK) activation on VSMC proliferation and ROS production by using rat aortic VSMCs in vitro and in vivo. Nifedipine induced phosphorylation of AMPK in a dose-and time-dependent manner, and inhibited rat VSMC proliferation and ROS production following stimulation with 15% fetal bovine serum (FBS). Nifedipine also blocked the FBS-stimulated cell cycle progression through the G0/G1 arrest. Compound C, a specific inhibitor of AMPK, or AMPK siRNA reduced the nifedipine-mediated inhibition of VSMC proliferation. As an upstream kinase, LKB1 is required for nifedipine-induced AMPK activation in VSMCs. 7 days oral administration of 1 mg/kg nifedipine resulted in activation of LKB1 and AMPK in vivo. These data suggest that nifedipine suppress the VSMC proliferation and ROS production via activating LKB1-AMPK pathway.     

降钙素基因相关肽抑制内皮素促血管平滑肌细胞增殖作用

本工作应用培养的自发性高血压大鼠主动脉平滑肌细胞.通过~3H-胸腺嘧啶核苷及~3H-亮氨酸参入的方法,观察到降钙素基因相关肽明显抑制培养的血管平滑肌细胞的增殖和内皮素促血管平滑肌细胞增值作用.提示降钙素基因相关肽可能是机体天然存在的内皮素拮抗剂。     

Sauchinone inhibits angiotensin II-induced proliferation and migration of vascular smooth muscle cells

Hypertension is a common type of cardiovascular disease that remains a major cause of death in the world. Vascular remodelling is an important complication of hypertension, and vascular smooth muscle cells (VSMCs) play a major role in vascular remodelling. Sauchinone is one of the active lignins which has been found to possess vascular protective effects. However, the functional role of sauchinone in hypertension has not been investigated. The aim of this study was to evaluate the role of sauchinone in the angiotensin II (Ang II)-induced vascular remodelling model in VSMCs. The results showed that treatment of sauchinone inhibited Ang II-induced VSMCs proliferation and migration in VSMCs. Sauchinone treatment suppressed the reactive oxygen species (ROS) production and NADPH oxidase (NOX) activity in Ang II-induced VSMCs. The inhibitory effects of Ang II on expressions of VSMCs phenotype markers including α-smooth muscle actin (α-SMA), calponin, osteopontin were mitigated by sauchinone treatment. Furthermore, sauchinone inhibited Ang II-induced over-activation of TGF-β1/Smad3 signalling pathway in VSMCs. Taken together, this study identified sauchinone as a potential agent for preventing vascular remodelling in hypertension.     

Ajoene,a garlic compound,inhibits protein prenylation and arterial smooth muscle cell proliferation

(1) Ajoene is a garlic compound with anti-platelet properties and, in addition, was shown to inhibit cholesterol biosynthesis by affecting 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase and late enzymatic steps of the mevalonate (MVA) pathway. (2) MVA constitutes the precursor not only of cholesterol, but also of a number of non-sterol isoprenoids, such as farnesyl and geranylgeranyl groups. Covalent attachment of these MVA-derived isoprenoid groups (prenylation) is a required function of several proteins that regulate cell proliferation. We investigated the effect of ajoene on rat aortic smooth muscle cell proliferation as related to protein prenylation. (3) Cell counting, DNA synthesis, and cell cycle analysis showed that ajoene (1-50 micro M) interfered with the progression of the G1 phase of the cell cycle, and inhibited rat SMC proliferation. (4) Similar to the HMG-CoA reductase inhibitor simvastatin, ajoene inhibited cholesterol biosynthesis. However, in contrast to simvastatin, the antiproliferative effect of ajoene was not prevented by the addition of MVA, farnesol (FOH), and geranylgeraniol (GGOH). Labelling of smooth muscle cell cellular proteins with [3H]-FOH and [3H]-GGOH was significantly inhibited by ajoene. (5) In vitro assays for protein farnesyltransferase (PFTase) and protein geranylgeranyltransferase type I (PGGTase-I) confirmed that ajoene inhibits protein prenylation. High performance liquid chromatography (HPLC) and mass spectrometry analyses also demonstrated that ajoene causes a covalent modification of the cysteine SH group of a peptide substrate for protein PGGTase-I. (6) Altogether, our results provide evidence that ajoene interferes with the protein prenylation reaction, an effect that may contribute to its inhibition of SMC proliferation.     

丝裂原活化蛋白激酶参与血小板源生长因子刺激的大鼠主动脉平滑肌细胞增殖(英文)

选择大鼠主动脉平滑肌细胞作为细胞模型 ,观察丝裂原活化蛋白激酶 ( MAPK)信号通路在血小板源生长因子 ( PDGF)诱导的血管平滑肌细胞( VSMC)增殖中的作用。用 [3 H]Td R参入率作为衡量 VSMC增殖的指标 ,以 Western-印迹方法 ,用磷酸化一抗测 MAPK磷酸化的程度作为衡量 MAPK活性的指标 ,实验结果发现 ,PDGF( 0 .0 2 - 2 0μg·L-1)诱导 VSMC增殖呈剂量依赖性。 PDGF( 2μg· L-1)能持续性激活 MAPK。用 PD980 59( 1 0 -1 0 0 mol· L-1)预处理 1 5min后 ,MAPK活性较对照组均有明显差别 ( P<0 .0 5) .MAPK反义寡核苷酸能明显抑制 PDGF诱导的 MAPK的激活 ,并明显抑制 VSMC[3 H]Td R参入。上述结果表明 ,MAPK参与 PDGF促细胞增殖的信号途经 ,它的持续性激活与细胞增殖有关 ,针对 p42 /p44MAPK设计的反义寡核苷酸类能有效抑制 PDGF诱导的血管平滑肌细胞增殖。     

Resveratrol inhibits rat aortic vascular smooth muscle cell proliferation via estrogen receptor dependent nitric oxide production

Vascular smooth muscle cell (VSMC) proliferation is pivotal in the progression of hypertension, atherosclerosis, and restenosis. Resveratrol is a grape polyphenol that is implicated as an important contributor to red wine's vascular protective effects. Its antimitogenic action on VSMC is attributed to an array of pleiotropic effects, including modulation of the estrogen receptor (ER). To elucidate the mechanisms underlying resveratrol-mediated ER modulation and its inhibition of VSMC proliferation, we treated VSMC with resveratrol with or without the ER antagonist ICI 182,780 and measured cell proliferation and nitric oxide (NO) production. Resveratrol dose-dependently decreased VSMC DNA synthesis, with a half maximal inhibitory concentration (IC50) of 3.73+/-0.57 microM, and dramatically slowed cell growth, but did not induce VSMC apoptosis. Resveratrol-mediated decrease in proliferation was reversed by cotreatment with ICI 182,780, and resveratrol effectively competed with 17beta-estradiol for binding to the ER, exhibiting an IC50 of 8.92+/-0.14 microM. Resveratrol induced a sustained increase in ER-dependent NO production. Further, resveratrol-mediated decrease in VSMC proliferation was blunted by cotreatment with the general nitric oxide synthase (NOS) inhibitor N5-(1-Iminomethyl)-L-ornithine, dihydrochloride or with the inducible NOS (iNOS)-selective inhibitor S,S'-1,4-phenylene-bis (1,2-ethanediyl)bis-isothiourea, dihydrobromide, but not with the neuronal NOS-selective inhibitor 7-nitroindazole. Though resveratrol did not alter iNOS protein levels, it dose-dependently increased levels of iNOS activity, of the iNOS cofactor tetrahydrobiopterin (BH4), and of guanosine triphosphate cyclohydrolase I protein, the rate-limiting enzyme in BH4 biosynthesis. In addition, all of these effects were abolished by cotreatment with ICI 182,780. Thus, the antimitogenic effects of resveratrol on VSMC may be mediated by an ER-induced increase in iNOS activity.     

Hemin inhibits hypertensive rat vascular smooth muscle cell proliferation through regulation of cyclin D and p21

We tested the hypothesis that HO-1 (heme oxygenase-1) activity varied between vascular smooth muscle cells (VSMC) in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. HO-1 levels were measured under baseline and hemin-stimulated conditions and cell proliferation was monitored. Basal HO-1 levels in untreated cells were lower in SHR compared to WKY rats. Treatment with hemin increased HO-1 mRNA and protein levels in the cells obtained from WKY rats compared to that of SHR rats. However, hemin-treatment showed a greater inhibitory effect on VSMC proliferation in SHR rats than in WKY rats. Tin protoporphyrin IX (SnPPIX) showed a greater reversal of the anti-proliferative effect of hemin on cells from SHR rats than WKY. Similarly, VSMC proliferation from SHR was significantly inhibited in VSMC transfected with the HO-1 gene. These inhibitory effects were associated with cell cycle arrest in the G1 phase. The level of cyclin D, and cyclin dependent kinase inhibitor p21 was higher in SHR cells progressing through the G1 phase. Treatment of the cells with hemin down-regulated the expression of cyclin D and up-regulated that of p21. These results indicate that hemin, an HO-1 inducer, may play a more critical role in VSMC proliferation in SHR than WKY.     

丝裂原活化蛋白激酶参与血小板源生长因子刺激的大鼠主动脉平滑肌细胞增殖(英文)

选择大鼠主动脉平滑肌细胞作为细胞模型 ,观察丝裂原活化蛋白激酶 ( MAPK)信号通路在血小板源生长因子 ( PDGF)诱导的血管平滑肌细胞( VSMC)增殖中的作用。用 [3 H]Td R参入率作为衡量 VSMC增殖的指标 ,以 Western-印迹方法 ,用磷酸化一抗测 MAPK磷酸化的程度作为衡量 MAPK活性的指标 ,实验结果发现 ,PDGF( 0 .0 2 - 2 0μg·L-1)诱导 VSMC增殖呈剂量依赖性。 PDGF( 2μg· L-1)能持续性激活 MAPK。用 PD980 59( 1 0 -1 0 0 mol· L-1)预处理 1 5min后 ,MAPK活性较对照组均有明显差别 ( P<0 .0 5) .MAPK反义寡核苷酸能明显抑制 PDGF诱导的 MAPK的激活 ,并明显抑制 VSMC[3 H]Td R参入。上述结果表明 ,MAPK参与 PDGF促细胞增殖的信号途经 ,它的持续性激活与细胞增殖有关 ,针对 p42 /p44MAPK设计的反义寡核苷酸类能有效抑制 PDGF诱导的血管平滑肌细胞增殖。     

A peptide analogue of thrombin receptor-activating peptide inhibits thrombin and thrombin-receptor-activating peptide-induced vascular smooth muscle cell proliferation

The serine protease thrombin, in addition to its pivotal role in the coagulation cascade, plays an important role in the development of atherosclerosis and restenosis by inducing smooth cell proliferation. Thrombin exerts its cellular effects mainly by cleaving its own receptor, leaving a new NH2-terminus that can act as a tethered ligand to activate the thrombin receptor. Peptides derived from the new NH2-terminus are able to fully activate thrombin receptor and mimic cellular effects of thrombin. Peptides with structural similarities to the tethered ligand have been tested for their ability to prevent thrombin- and tethered ligand-induced platelet aggregation and thrombus formation. We synthesized a peptide with multiple alanine substitutions in both critical and noncritical residues of tethered ligand that specifically inhibited platelet aggregation induced by thrombin and thrombin receptor-activating peptide and prevented thrombus formation in a rabbit thrombosis model. In the present study we demonstrate that this peptide inhibited only thrombin- and tethered ligand-induced human vascular smooth muscle cell proliferation as determined by (3H)-thymidine incorporation and has no effect on platelet-derived growth factor and serum-induced smooth muscle cell proliferation. The inhibitory effect of this peptide is dependent on the concentration of the antagonist used and length of preincubation time. The possible mechanism by which this peptide exerts its inhibitory effect may by desensitizing the thrombin receptor. The results of the present study suggest that apart from being antithrombotic, tethered ligand antagonist peptides can also act as antiatherosclerotic or antirestenotic agents.     

川芎嗪通过下调JNK磷酸化抑制PM_(2.5)诱导的血管平滑肌细胞增殖

目的探讨川芎嗪(TMP)对PM_(2.5)诱导的大鼠血管平滑肌细胞(VSMC)增殖的影响及作用机制。方法以PM_(2.5)20,200和400 mg·L~(-1)染毒培养VSMC 24 h,MTT法检测VSMC存活,ELISA法检测细胞黏附分子1(VCAM-1)含量,放射免疫分析(RIA)法和硝酸还原酶法分别检测内皮素1(ET-1)和一氧化氮(NO)含量,Western蛋白印迹法检测VSMC中成纤维细胞生长因子受体1(FGFR-1)蛋白表达。分别加入TMP 20,200和2000 mg·L~(-1)及JNK抑制剂SP600125 10μmol·L~(-1)检测TMP对PM_(2.5)的干预作用及机制。结果与正常对照组比较,PM_(2.5)200和400 mg·L~(-1)处理组A_(570 nm)显著升高,VCAM-1和ET-1分泌增加,NO分泌降低,p-JNK及FGFR-1蛋白表达显著增加(P<0.01);PM_(2.5)20 mg·L~(-1)处理组上述指标无显著变化。与PM_(2.5)200 mg·L~(-1)处理组比较,PM_(2.5)200 mg·L~(-1)+TMP 200和2000 mg·L~(-1)预处理组A_(570 nm)显著降低,VCAM-1及ET-1分泌降低,NO分泌增加,p-JNK和FGFR-1蛋白表达显著降低(P<0.01);PM_(2.5)2 00 mg·L~(-1)+TMP 20 mg·L~(-1)预处理组无显著变化。与PM_(2.5)200 mg·L~(-1)+TMP 2000 mg·L~(-1)预处理组比较,PM_(2.5)200 mg·L~(-1)+TMP 2000 mg·L~(-1)+SP600125 10μmol·L~(-1)抑制剂组可进一步增强TMP对上述指标的影响(P<0.05,P<0.01)。结论 TMP可能通过下调JNK磷酸化,并调节VSMC内FGFR-1蛋白表达及VCAM-1,ET-1和NO含量,抑制PM_(2.5)诱导的VSMC增殖。     

Leptin inhibits cell growth of human vascular smooth muscle cells

Elevated leptin levels are thought to contribute to the individual cardiovascular risk, however, the role of leptin in the pathogenesis of atherosclerosis remains unclear. The aim of our study was to elucidate the effects of leptin on growth of human vascular smooth muscle cells (VSMC) and leptin receptor expression. By establishing a new quantitative real-time PCR for leptin receptor (ObR) isoforms we showed that the short isoforms of ObR were expressed in a 10- to 27-fold excess compared to the long isoform in cultured human VSMCs. Incubation of VSMCs with 100 ng/ml leptin downregulated the short isoforms significantly, whereas the long isoform was not influenced. Increasing leptin concentrations of 50 and 100 ng/ml significantly reduced the cell number of VSMCs compared to untreated controls. Our findings suggest a role for leptin in vascular smooth muscle cell growth, associated to a downregulation of leptin receptor isoforms.     

Astrapterocarpan isolated from Astragalus membranaceus inhibits proliferation of vascular smooth muscle cells

The inhibitory effects of astrapterocarpan, formononetin, and calycosin isolated from Astragalus membraneceus on platelet-derived growth factor (PDGF)-BB-induced proliferative response in rat vascular smooth muscle cells (A10 cells) were investigated. Astrapterocarpan significantly inhibited PDGF-BB-induced cell proliferation and DNA synthesis in a concentration-dependent manner. This inhibition was not attributed to toxicity. In contrast, formononetin and calycosin had no effect. We next examined the effect of astrapterocarpan on PDGF-BB signal transduction. Astrapterocarpan inhibited PDGF-BB-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERIC1/2) mitogen-activated protein (MAP) kinase. However, this compound had no effect on phosphorylation of PDGF-beta-receptor, Akt kinase and p38 MAP kinase. These results indicated that astrapterocarpan inhibits PDGF-BB-induced vascular smooth muscle cell proliferation and that this effect may be mediated, at least in part, by inhibition of the ERK1/2 MAP kinase cascade.     

Zoledronate inhibits the proliferation, adhesion and migration of vascular smooth muscle cells

Bisphosphonates, which are extensively used in bone-related disorders, have been reported to inhibit atherosclerosis and neointimal hyperplasia. In the present study, we investigated the effects of a bisphosphonate, zoledronate, on the proliferation, adhesion, migration and microstructure of vascular smooth muscle cells (VSMCs) from Sprague-Dawley rats. It was shown that zoledronate suppressed VSMCs proliferation after 48 h cultivation in a dose depend manner, most obviously at concentrations above 10 µM. Cell cycle analysis indicated that zoledronate inhibited the proliferation of VSMCs via cell cycle arrest at S/G2/M phase. This inhibition was not associated with cell death. In a modified Boyden chamber model, it was shown that zoledronate dose-dependently inhibited VSMCs adhesion to collagen and migration stimulated by platelet-derived growth factor-BB. Western blot analysis suggested that zoledronate significantly inhibited the phosphorylation of focal adhesion kinase. Furthermore, we observed that more and more VSMCs changed from a bipolar appearance to a globular shape under inverted light microscope as zoledronate concentration increased from 0.1 to 100 µM. Images under transmission electron microscope confirmed this morphological change, and many electron density bodies were observed in zoledronate-treated VSMCs. These findings indicated that bisphosphonates' effects of suppressing atherosclerosis and neointimal hyperplasia might be due to inhibition of VSMCs, at least for zoledronate.     

Inhibitory effect of pentalenolactone on vascular smooth muscle cell proliferation

The effect of pentalenolactone, an inhibitor of glyceraldehyde-3-phosphate dehydrogenase, on rat vascular smooth muscle cell proliferation was studied. Addition of pentalenolactone together with serum to quiescent cells dose-dependently inhibited cell proliferation and DNA synthesis. This inhibition was not associated with cell death. When quiescent cells were stimulated with serum and then treated with pentalenolactone, the inhibitory effect on the DNA synthesis declined gradually. A similar result was obtained when PD 98059 (2'-amino-3'-methoxyflavone), an inhibitor of extracellular signal-regulated kinase1/2 (ERK1/2) kinase (MEK1/2), was added to the cells after serum stimulation. Pentalenolactone inhibited serum or protein kinase C activator (phorbol 12,13-dibutyrate)-induced phosphorylation of ERK1/2 and MEK1/2. In contrast, pentalenolactone had little effect on platelet-derived growth factor receptor autophosphorylation. Taken together, these results indicate that pentalenolactone inhibits vascular smooth muscle cell proliferation, and that this inhibition appears to be mediated by inhibition of the ERK1/2 cascade.