Inhibition Of Smooth Muscle Cell Migration Research Articles

Contribution of transcription factor EB to adipoRon-induced inhibition of arterial smooth muscle cell proliferation and migration.

Abnormal vascular smooth muscle cell (SMC) dedifferentiation with increased proliferation and migration during pathological vascular remodeling is associated with vascular disorders, such as atherosclerosis and in-stent restenosis. AdipoRon, a selective agonist of adiponectin receptor, has been shown to protect against vascular remodeling by preventing SMC dedifferentiation. However, the molecular mechanisms that mediate adipoRon-induced SMC differentiation are not well understood. The present study aimed to elucidate the role of transcription factor EB (TFEB), a master regulator of autophagy, in mediating adipoRon's effect on SMCs. In cultured arterial SMCs, adipoRon dose-dependently increased TFEB activation, which is accompanied by upregulated transcription of genes involved in autophagy pathway and enhanced autophagic flux. In parallel, adipoRon suppressed serum-induced cell proliferation and caused cell cycle arrest. Moreover, adipoRon inhibited SMC migration as characterized by wound-healing retardation, F-actin reorganization, and matrix metalloproteinase-9 downregulation. These inhibitory effects of adipoRon on proliferation and migration were attenuated by TFEB gene silencing. Mechanistically, activation of TFEB by adipoRon is dependent on intracellular calcium, but it is not associated with changes in AMPK, ERK1/2, Akt, or molecular target of rapamycin complex 1 activation. Using ex vivo aortic explants, we demonstrated that adipoRon inhibited sprouts that had outgrown from aortic rings, whereas lentiviral TFEB shRNA transduction significantly reversed this effect of adipoRon on aortic rings. Taken together, our results indicate that adipoRon activates TFEB signaling that helps maintain the quiescent and differentiated status of arterial SMCs, preventing abnormal SMC dedifferentiation. This study provides novel mechanistic insights into understanding the therapeutic effects of adipoRon on TFEB signaling and pathological vascular remodeling.

Uncoupling Protein 2 Inhibits Myointimal Hyperplasia in Preclinical Animal Models of Vascular Injury.

BackgroundIntracoronary stent restenosis, characterized by excessive smooth muscle cell (SMC) proliferation and myointimal hyperplasia, remains a clinical challenge. Mitochondrial membrane potential has been linked to the proliferative rate of SMCs. This study aimed to screen a critical gene regulating mitochondrial potential and to confirm its effects on myointimal formation in preclinical animal models.Methods and ResultsWe performed transcriptome screening for genes differentially expressed in ligated versus unligated mouse carotid arteries. We observed that uncoupling protein 2 gene (Ucp2) mRNA, encoding UCP2, was transiently upregulated during the first 3 days after ligation and then significantly downregulated from day 7 through day 21, during which time neointima formed remarkably. The UCP2 protein level also declined after day 7 of ligation. In ligated carotid arteries, Ucp2 −/− mice, compared with wild‐type littermates, exhibited accelerated myointimal formation, which was associated with increased superoxide production and can be attenuated by treatment with antioxidant 4‐hydroxy‐2,2,6,6‐tetramethyl‐piperidinoxyl (TEMPOL). Knockdown of UCP2 enhanced human aortic SMC migration and proliferation that can also be attenuated by TEMPOL, whereas UCP2 overexpression inhibited SMC migration and proliferation, along with decreased activity of nuclear factor‐κB. Moreover, nuclear factor‐κB inhibitor attenuated UCP2 knockdown‐enhanced SMC proliferation. Adenovirus‐mediated overexpression of UCP2 inhibited myointimal formation in balloon‐injured carotid arteries of rats and rabbits and in‐stent stenosis of porcine coronary arteries. Moreover, UCP2 overexpression also suppressed neointimal hyperplasia in cultured human saphenous vein ex vivo.ConclusionsUCP2 inhibits myointimal hyperplasia after vascular injury, probably through suppressing nuclear factor‐κB–dependent SMC proliferation and migration, rendering UCP2 a potential therapeutic target against restenosis.

Recombinant soluble apyrase APT102 inhibits thrombosis and intimal hyperplasia in vein grafts without adversely affecting hemostasis or re‐endothelialization

Background Occlusion of vein grafts (VGs) after bypass surgery, owing to thrombosis and intimal hyperplasia (IH), is a major clinical problem. Apyrases are enzymes that scavenge extracellular ATP and ADP, and promote adenosine formation at sites of vascular injury, and hence have the potential to inhibit VG pathology. Objectives To examine the effects of recombinant soluble human apyrase, APT102, on platelets, smooth muscle cells (SMCs) and endothelial cells (ECs) in vitro, and on thrombosis and IH in murine VGs. Methods SMC and EC proliferation and migration were studied in vitro. Inferior vena cava segments from donor mice were grafted into carotid arteries of recipient mice. Results APT102 potently inhibited ADP-induced platelet aggregation and VG thrombosis, but it did not impair surgical hemostasis. APT102 did not directly inhibit SMC or EC proliferation, but significantly attenuated the effects of ATP on SMC and EC proliferation. APT102 significantly inhibited SMC migration, but did not inhibit EC migration, which may be mediated, at least in part, by inhibition of SMC, but not EC, migration by adenosine. At 4 weeks after surgery, there was significantly less IH in VGs of APT102-treated mice than in control VGs. APT102 significantly inhibited cell proliferation in VGs, but did not inhibit re-endothelialization. Conclusions Systemic administration of a recombinant human apyrase inhibits thrombosis and IH in VGs without increasing bleeding or compromising re-endothelialization. These results suggest that APT102 has the potential to become a novel, single-drug treatment strategy to prevent multiple pathologic processes that drive early adverse remodeling and occlusion of VGs.

Pharmacological Targeting of Plasminogen Activator Inhibitor-1 Decreases Vascular Smooth Muscle Cell Migration and Neointima Formation.

Plasminogen activator inhibitor-1 (PAI-1), a serine protease inhibitor that promotes and inhibits cell migration, plays a complex and important role in adverse vascular remodeling. Little is known about the effects of pharmacological PAI-1 inhibitors, an emerging drug class, on migration of vascular smooth muscle cells (SMCs) and endothelial cells (ECs), crucial mediators of vascular remodeling. We investigated the effects of PAI-039 (tiplaxtinin), a specific PAI-1 inhibitor, on SMC and EC migration in vitro and vascular remodeling in vivo. PAI-039 inhibited SMC migration through collagen gels, including those supplemented with vitronectin and other extracellular matrix proteins, but did not inhibit migration of PAI-1-deficient SMCs, suggesting that its antimigratory effects were PAI-1-specific and physiologically relevant. However, PAI-039 did not inhibit EC migration. PAI-039 inhibited phosphorylation and nuclear translocation of signal transducers and activators of transcription-1 in SMCs, but had no discernable effect on signal transducer and activator of transcription-1 signaling in ECs. Expression of low-density lipoprotein receptor-related protein 1, a motogenic PAI-1 receptor that activates Janus kinase/signal transducers and activators of transcription-1 signaling, was markedly lower in ECs than in SMCs. Notably, PAI-039 significantly inhibited intimal hyperplasia and inflammation in murine models of adverse vascular remodeling, but did not adversely affect re-endothelialization after endothelium-denuding mechanical vascular injury. PAI-039 inhibits SMC migration and intimal hyperplasia, while having no inhibitory effect on ECs, which seems to be because of differences in PAI-1-dependent low-density lipoprotein receptor-related protein 1/Janus kinase/signal transducer and activator of transcription-1 signaling between SMCs and ECs. These findings suggest that PAI-1 may be an important therapeutic target in obstructive vascular diseases characterized by neointimal hyperplasia.

Epac1 Deficiency Attenuated Vascular Smooth Muscle Cell Migration and Neointimal Formation.

Vascular smooth muscle cell (SMC) migration causes neointima, which is related to vascular remodeling after mechanical injury and atherosclerosis development. We previously reported that an exchange protein activated by cAMP (Epac) 1 was upregulated in mouse arterial neointima and promoted SMC migration. In this study, we examined the molecular mechanisms of Epac1-induced SMC migration and the effect of Epac1 deficiency on vascular remodeling in vivo. Platelet-derived growth factor-BB promoted a 2-fold increase in SMC migration in a primary culture of aortic SMCs obtained from Epac1(+/+) mice (Epac1(+/+)-ASMCs), whereas there was only a 1.2-fold increase in Epac1(-/-)-ASMCs. The degree of platelet-derived growth factor-BB-induced increase in intracellular Ca(2+) was smaller in Fura2-labeled Epac1(-/-)-ASMCs than in Epac1(+/+)-ASMCs. In Epac1(+/+)-ASMCs, an Epac-selective cAMP analog or platelet-derived growth factor-BB increased lamellipodia accompanied by cofilin dephosphorylation, which is induced by Ca(2+) signaling, whereas these effects were rarely observed in Epac1(-/-)-ASMCs. Furthermore, 4 weeks after femoral artery injury, prominent neointima were formed in Epac1(+/+) mice, whereas neointima formation was significantly attenuated in Epac1(-/-) mice in which dephosphorylation of cofilin was inhibited. The chimeric mice generated by bone marrow cell transplantation from Epac1(+/+) into Epac1(-/-) mice and vice versa demonstrated that the genetic background of vascular tissues, including SMCs rather than of bone marrow-derived cells affected Epac1-mediated neointima formation. These data suggest that Epac1 deficiency attenuates neointima formation through, at least in part, inhibition of SMC migration, in which a decrease in Ca(2+) influx and a suppression of cofilin-mediated lamellipodia formation occur.

Pterostilbene Inhibits Vascular Smooth Muscle Cells Migration and Matrix Metalloproteinase-2 through Modulation of MAPK Pathway.

Smooth muscle cells (SMCs) migration and matrix metalloproteinase-2 (MMP-2) activation are main roles in atherosclerosis. Pterostilbene (trans-3, 5-dimethoxy-4-hydroxystilbene) is known to have various pharmacologic effects such as anti-inflammatory and anticarcinogenic properties. The present study aimed to investigate the anti-atheroscleroic property of pterostilbene in the rat smooth muscle cell (SMC) A7r9 cell lines and the underlying mechanisms. In this study, pterostilbene treatment significantly inhibited migration/invasion capacities of in A7r9 cell. Pterostilbene was also found to significantly decreased MMP-2 activity and expression by gelatin zymography and western blot assay in SMC. In the MAPK signaling pathway, western blot assay also indicated that pterostilbene up-regulated the phosphorylation of extracellular-signal-regulated kinase (Erk)1/2. Moreover, inhibition of Erk1/2 by specific inhibitors significantly abolished the pterostilbene-decreased expression of MMP-2 and migration/invasion capacities. These findings suggest that pterostilbene inhibited SMC migration and that MMP-2 activation could be mediated via Erk1/2 phosphorylation. It is further possible that pterostilbene could play a novel role in the treatment of atherosclerosis. Pterostilbene is a plant polyphenol compound that is principally found in blueberries. In this study, we found that pterostilbene could inhibit SMCs migration via down-regulation of MMP-2. Particularly, expression of MMP-2 was found to be strongly associated with the phosphorylation of Erk1/2.

Abstract 188: Selective Inhibition of Vascular Smooth Muscle Cell Migration by Targeting Plasminogen Activator Inhibitor-1

Introduction: Plasminogen activator inhibitor-1 (PAI-1) is the primary inhibitor of mammalian plasminogen activators and an important regulator of cell migration. We have shown that tiplaxtinin, a small molecule, specific inhibitor of PAI-1, inhibits intimal hyperplasia in a murine vein graft model. However, little is known about the effects of pharmacological inhibition of PAI-1 on vascular cell migration under physiologically relevant conditions. Methods: We studied the effects of tiplaxtinin on migration of smooth muscle cells (SMCs) and endothelial cells (ECs). Results: Tiplaxtinin significantly inhibited migration of murine SMCs through 3-dimensional (3-D) collagen matrix in a concentration-dependent manner. Tiplaxtinin did not inhibit SMC proliferation, and it did not inhibit migration of PAI-1-deficient SMCs, suggesting that tiplaxtinin’s effect on SMCs was non-toxic and PAI-1-dependent. The anti-migratory effect of tiplaxtinin on SMCs was preserved in collagen 3-D matrix containing vitronectin and other extracellular matrix molecules, further supporting the physiological significance of the effect. In contrast to SMCs, tiplaxtinin did not inhibit migration of human aortic ECs in vitro or murine ECs in vivo, the latter assessed in a murine carotid injury model. To study the basis for the differential effect of tiplaxtinin on SMCs vs. ECs, we compared expression of LDL receptor-related protein 1 (LRP1), a motogenic receptor for PAI-1, between cell types by RT-PCR and found that LRP1 gene expression was significantly lower in ECs than in SMCs. Furthermore, recombinant PAI-1 stimulated the migration of wild-type mouse embryonic fibroblasts (MEFs), but not LRP1-deficient MEFs. Conclusions: Tiplaxtinin, a pharmacological inhibitor of PAI-1, inhibits SMC migration under physiological conditions, while having no inhibitory effect on EC migration. The differential effect of PAI-1 inhibition on SMCs vs. ECs appears to be mediated by LRP1 and may be of clinical significance, as it is advantageous to prevent intimal hyperplasia by inhibiting SMC migration without inhibiting EC migration, which is key to preserving an intact, anti-thrombotic vascular endothelium.

Nox2 mediates high fat high sucrose diet-induced nitric oxide dysfunction and inflammation in aortic smooth muscle cells

Diet-induced obesity and metabolic syndrome are important contributors to cardiovascular diseases. The decreased nitric oxide (NO) bioactivity in endothelium and the impaired response of smooth muscle cell (SMC) to NO significantly contribute to vascular pathologies, including atherosclerosis and arterial restenosis after angioplasty. Sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) is an important mediator of NO function in both endothelial cells and SMCs, and its irreversible oxidation impairs its stimulation by NO. We used C57BL/6J mice fed a high fat high sucrose diet (HFHSD) to study the role of SMC SERCA in diet-induced obesity and metabolic syndrome. We found that HFHSD upregulated Nox2 based NADPH oxidase, induced inflammation, increased irreversible SERCA oxidation, and suppressed the response of aortic SERCA to NO. Cultured aortic SMCs from mice fed HFHSD showed increased reactive oxygen species production, Nox2 upregulation, irreversible SERCA oxidation, inflammation, and a decreased ability of NO to inhibit SMC migration. Overexpression of wild type SERCA2b or downregulation of Nox2 restored NO-mediated inhibition of migration in SMCs isolated from HFHSD-fed mice. In addition, tumor necrosis factor alpha (TNFα) increased Nox2 which induced SERCA oxidation and inflammation. Taken together, Nox2 induced by HFHSD plays significant roles in controlling SMC responses to NO and TNFα-mediated inflammation, which may contribute to the development of cardiovascular diseases in diet-induced obesity and metabolic syndrome.

In vivo Effect of Insulin to Decrease Matrix Metalloproteinase-2 and -9 Activity after Arterial Injury

In vitro, insulin has both growth-promoting and vasculoprotective effects. In vivo, the effect of insulin is mainly protective. Insulin treatment (3 U/day) decreases smooth muscle cell (SMC) migration and neointimal growth after carotid angioplasty in normal rats maintained at normoglycemia by oral glucose. SMC migration requires limited proteolysis of the extracellular matrix, which is mediated by matrix metalloproteinases (MMPs). In this study, we investigated the effects of normoglycemic hyperinsulinemia on MMP activity after balloon angioplasty. Rats were divided into three groups: (1) control implants and tap water; (2) control implants and oral glucose, and (3) insulin implants (3 U/day) and oral glucose. Results: Gelatin zymography revealed that insulin reduced the gelatinolytic activity of pro-MMP-2 by 46% (p < 0.05), MMP-2 by 44% (p < 0.05) and MMP-9 by 51% (p < 0.05) compared to controls after arterial injury. Insulin also reduced mRNA levels of MMP-2 (p < 0.05) and MMP-9 (p < 0.05) and protein levels of MMP-2 (p < 0.05). In contrast, there were no significant changes in membrane-type 1 MMP protein and tissue inhibitors of MMP activity after insulin treatment. Thus, these results suggest a mechanism by which insulin inhibits SMC migration and supports a vasculoprotective role for insulin in vivo.

Smooth muscle nitric oxide responsiveness predicts clinical maturation of hemodialysis fistulae

The arteriovenous fistula is the preferred type of hemodialysis vascular access for patients with end‐stage renal disease, but 50% of newly created fistulas fail to mature adequately for use. Stenosis due to neointimal hyperplasia is present in a large proportion of fistulae with maturation failure suggesting that local mechanisms controlling vascular smooth muscle cell (SMC) migration are important contributors to maturation failure. Our objective is to manipulate local factors present in the vein at the time of fistula surgery in order to prevent maturation failure. Using SMC explants from vein tissue obtained at the time of fistula creation from patients enrolled in the NIH Hemodialysis Fistula Maturation Study, we find that among patients with subsequent fistula maturation failure, •NO inhibits SMC migration significantly less. Using strategies initially developed in animal models, we find that impaired •NO inhibition is associated with oxidation of the calcium regulatory protein, sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA), and can be reversed by overexpressing SERCA or by down‐regulating Nox4 NADPH oxidase. Our data suggest that SMC •NO responsiveness may be predictive of fistula maturation outcome and that therapeutic restoration of •NO responsiveness through manipulation of local factors may prevent fistula maturation failure.Funding: R21DK084390 and R01 HL31607

Chemotactic effect of prorenin on human aortic smooth muscle cells: a novel function of the (pro)renin receptor

The discovery of a specific prorenin receptor (PRR) suggests a biological function of prorenin that is independent of angiotensin I production. In the present study, we investigated the role of PRR on smooth muscle cell (SMC) migration. PRR was expressed in human mammary arteries and in cultured human aortic SMCs. Prorenin induced SMC migration in a dose-dependent manner, as assessed by Boyden chamber chemotaxis assay, and increased SMC random motility, as determined by video microscopy. The prorenin decoy peptide inhibited SMC migration in response to prorenin, and knockdown of PRR by small interfering RNA completely inhibited the migratory response to prorenin, demonstrating that the chemotactic action of prorenin is mediated by the PRR. Prorenin induced cytoskeleton reorganization and lamellipodia formation and increased the intracellular levels of both RhoA-GTP and Rac1-GTP through PRR. These effects were required for SMC migration, because the suppression by small interfering RNA of either Rac1 or RhoA GTP-bound forms completely blocked the PRR-mediated chemotactic effect. Prorenin also induced the formation of larger focal adhesions and cleavage of the focal adhesion kinase (pp125(FAK)) into two main fragments with molecular weights of 50 and 90 kDa. The generation of these two fragments of pp125(FAK) was reduced by the calpain inhibitor ALLN, which also inhibited SMC migration in response to prorenin. These results demonstrate that prorenin is a chemotactic factor for human aortic SMCs expressing PRR. This effect is elicited through reorganization of the cytoskeleton and focal adhesion, activation of RhoA and Rac1, and calpain-mediated cleavage of pp125(FAK).

Possible involvement of Cyclic-GMP-dependent protein kinase on matrix metalloproteinase-2 expression in rat aortic smooth muscle cells

Degradation and resynthesis of the extracellular matrix (ECM) are essential during tissue remodeling. Expansion of the vascular intima in atherosclerosis and restenosis following injury is dependent upon smooth muscle cell (SMC) proliferation and migration. The migration of SMC from media to intima critically depends on degradation of ECM protein by matrix metalloproteinases (MMPs). MMP inhibitors and eNOS gene transfer have been shown to inhibit SMC migration in vitro and neointima formation in vivo. Nitric oxide (NO) and cyclic-GMP have been implicated in the inhibition of VSMC migration. But, there are few studies addressing the role of NO signaling pathways on the expression of MMPs. Here we reported the involvement of cyclic-GMP-dependent protein kinase (PKG) (an important mediator of NO and cGMP signaling pathway in VSMC) on MMP-2 expression in rat aortic SMC. The goal of the present study was to gain insight into the possible involvement of PKG on MMP-2 in rat aortic SMC. MMP-2 protein and mRNA level and activity were downregulated in PKG-expressing cells as compared to PKG-deficient cells. In addition, the secretion of tissue inhibitor of metalloproteinase-2 (TIMP-2) was increased in PKG-expressing cells as compared to PKG-deficient cells. PKG-specific membrane permeable peptide inhibitor (DT-2) reverses the process. Interestingly, little or no changes of MMP-9 were observed throughout the study. Taken together our data suggest the possible role of PKG in the suppression of MMP-2.

Increased neointimal formation in cystathionine gamma-lyase deficient mice: Role of hydrogen sulfide in α5β1-integrin and matrix metalloproteinase-2 expression in smooth muscle cells

The physiological and pathological roles of hydrogen sulfide (H2S) in the regulation of cardiovacular functions have been recognized. Vascular smooth muscle cells (SMCs) express cystathionine gamma-lyase (CSE) and produce significant amount of H2S. Although growing evidence demonstated the anti-atherosclerotic effect of H2S, less is known about the contribution of the endogenous CSE/H2S pathway to the development of vascular remodeling. This study investigated the roles of the CSE/H2S pathway on SMC migration and neoimtimal formation by using CSE knockout (KO) mice. SMCs and aortic explants isolated from CSE KO mice exhibited more migration and outgrowth compared with that from wild-type (WT) mice, and exogenously applied NaHS (a H2S donor) at 100μM significantly inhibited SMC migration and outgrowth. SMCs became more elongated and spread in the absence of CSE, and fibronectin significantly stimulated adhesion and migration of SMCs from CSE KO mice (KO–SMCs) in comparison with SMCs from WT mice (WT–SMCs). The expressions of α5- and β1-integrins were significantly higher in KO–SMCs, and functional blocking of α5β1-integrin effectively abrogated KO–SMC migration. CSE deficiency also enhanced matrix metalloproteinase-2 (MMP-2) expression, and the selective blocking of MMP-2 decreased KO–SMC migration. NaHS treatment decreased both the expressions of α5- and β1-integrins and MMP-2. We further found that the expressions of α5- and β1-integrins as well as MMP-2, were stimulated by fibronectin, and that the blockage of α5β1-integrin reduced but overexpression of α5β1-integrin induced MMP-2 expression in both WT–SMCs and KO–SMCs. We also noticed that CSE deficiency in mice led to increased neointima formation in carotid arteries 4weeks after ligation, which were attenuated by NaHS administration. In conclusion, inhibition of SMC migration by H2S may be a novel target for the treatment of vascular occlusive disorder.

A perlecan-inducing compound significantly inhibits smooth muscle cell function and in-stent intimal hyperplasia: novel insights into the diverse biological effects of perlecan

Perlecan is the major heparan sulfate proteoglycan in the arterial wall. Previous studies have suggested that perlecan is a potent inhibitor of smooth muscle cell (SMC) activity. Therefore, perlecan overexpression may serve as a therapeutic modality to prevent in-stent restenosis (ISR). We have investigated a novel compound (RUS3108), identified in a SMC based screen to induce perlecan synthesis in SMC. The aims of this study were to assess the in vitro effects of RUS3108 and the effects of RUS3108-eluting stents in preventing ISR.Rabbit aortic SMC and bovine aortic endothelial cells (EC) were used in this study. Immunohistochemistry showed that RUS3108-treated SMC over-expressed perlecan indicating the drug effects. Furthermore, RUS3108 induced a SMC differentiated phenotype by SMembryonic staining. RUS3108 (1 microM) inhibited 3H-thymidine incorporation by >50%, which was completely reversed by a perlecan antibody. RUS3108 also inhibited SMC migration (Boyden chamber) and MMP-9 activity. In contrast, RUS3108 (100nM) modestly stimulated EC 3H-thymidine incorporation by 22% (p<0.02). In vivo, a total of 30 stents were deployed in rabbit iliac arteries as follows: 1) bare metal stents (n=10), 2) polymer onlycoated stents (n=10), and 3) polymer-coated stents containing RUS3108 (n=10). Rabbits were sacrificed at four weeks and stented segments were subjected to morphometric analysis. Intimal cross sectional area was significantly lower in the RUS3108-eluting stent group (0.31+ or -0.27 mm(2) versus 1.0 + or - 0.31 and 1.25 + or - 0.51 in the bare metal stents and polymer only coated stents groups, respectively, p<0.0001).RUS3108 is a novel perlecan-inducing compound, which is a potent inhibitor of SMC activity and a modest stimulator of EC proliferation. RUS3108-eluting stents may serve as an excellent modality for the prevention of ISR.

CREG inhibits migration of human vascular smooth muscle cells by mediating IGF-II endocytosis

We previously determined that the cellular repressor of E1A-stimulated genes, (CREG) plays a role in the maintenance of the mature phenotype of vascular smooth muscle cells (SMCs). This study aimed to identify the role of CREG in modulating the migration of SMCs. Recombinant virus-mediated CREG expression inhibited the cellular migration of cultured SMCs associated with down-regulated activity of matrix metalloproteinase-9 (MMP-9). In contrast, CREG knockdown via the retroviral transfer of short hairpin RNAs promoted cellular migration. Enzyme-linked immunosorbent assay and endocytosis analysis revealed that CREG knockdown attenuated the internalization and increased secretion of insulin-like growth factor (IGF)-II. Western blot analysis demonstrated that both phosphoinositide 3-kinase (PI3K) and phosphatase Akt were enhanced in CREG knockdown SMCs. Furthermore, the effect of CREG knockdown on SMC migration was abrogated in a dose-dependent manner by the addition of either IGF-II neutralizing antibody or the PI3K inhibitor, LY294002. These results indicate that the CREG knockdown-mediated increase in IGF-II secretion promoted cellular migration in SMCs via the PI3K/Akt signal pathway. Additionally, blockage of IGF-II binding to the mannose-6-phosphate/IGF-II receptor (M6P/IGF2R) by IGF2R antibody or recombinant IGF2R fragment attenuated the endocytosis of IGF-II in cells overexpressing CREG. This indicates that M6P/IGF2R is involved in the regulation of CREG-mediated IGF-II endocytosis. In summary, these data demonstrate for the first time that CREG plays a critical role in the inhibition of SMC migration, as well as maintaining SMCs in a mature phenotype. These results may provide a new therapeutic target for vascular disease associated with neointimal hyperplasia.

Resveratrol blocks interleukin-18-EMMPRIN cross-regulation and smooth muscle cell migration

Vascular smooth muscle cell (SMC) migration is an important mechanism in atherogenesis and postangioplasty arterial remodeling. Previously, we demonstrated that the proinflammatory cytokine interleukin (IL)-18 is a potent inducer of SMC migration. Since extracellular matrix metalloproteinase inducer (EMMPRIN) stimulates ECM degradation and facilitates cell migration, we investigated whether IL-18 and EMMPRIN regulate each other's expression, whether their cross talk induces SMC migration, and whether the phytoalexin resveratrol inhibits IL-18-EMMPRIN signaling and SMC migration. Our studies demonstrate that 1) IL-18 induces EMMPRIN mRNA and protein expressions and stimulates EMMPRIN secretion from human aortic SMCs; 2) IL-18 stimulates EMMPRIN expression via oxidative stress and phosphatidylinositol 3-kinase (PI3K)-Akt-ERK signaling; 3) IL-18-stimulated SMC migration is significantly blunted by EMMPRIN knockdown, EMMPRIN function-blocking antibodies, or adenoviral transduction of mutant EMMPRIN; 4) conversely, EMMPRIN stimulates IL-18 expression and secretion via PI3K, Akt, and ERK; and 5) resveratrol attenuates IL-18- and EMMPRIN-mediated PI3K, Akt, and ERK activations; blunts IL-18-mediated oxidative stress; blocks IL-18-EMMPRIN cross-regulation; and inhibits SMC migration. Collectively, our results demonstrate that the coexpression and regulation of IL-18 and EMMPRIN in the vessel wall may amplify the inflammatory cascade and promote atherosclerosis and remodeling. Resveratrol, via its antioxidant and anti-inflammatory properties, has the potential to inhibit the progression of atherosclerosis by blocking IL-18 and EMMPRIN cross-regulation and SMC migration.

Endothelial Nitric Oxide Synthase Gene Transfer Inhibits Human Smooth Muscle Cell Migration via Inhibition of Rho A

Smooth muscle cell (SMC) migration contributes to vascular remodeling. Nitric oxide (NO) produced via endothelial NO synthase (eNOS) inhibits SMC migration. This study analyzes signal transduction mechanisms of SMC migration targeted by NO. SMCs were cultured from human saphenous veins, and cell migration was studied using Boyden chambers. PDGF-BB (0.1 to 10 ng/ml) stimulated SMC migration in a concentration-dependent manner, which was inhibited by adenoviral-mediated overexpression of eNOS and by the NO donor diethylentriamine NONOate (DETANO, 10 to 10 mol/L). NO release was enhanced in eNOS-transduced SMCs, and L-NAME blunted the effect of eNOS overexpression on migration. PDGF-BB (10 ng/ml) activated Rho A, which was inhibited by the overexpression of eNOS by DETANO and by 8 bromo-cGMP. The inhibitory effect of DETANO on Rho A activity was prevented by the cGMP-dependant kinase inhibitor. Furthermore, inhibition of Rho A by C3 exoenzyme and inhibition of ROCK by Y-27632 diminished cell migration stimulated by PDGF-BB. Finally, in the cells overexpressing constitutively active ROCK mutant (CAT), DETANO failed to prevent PDGF-BB-induced SMC migration. In conclusion, NO inhibits human SMC migration via blockade of the Rho A pathway.

T‐type calcium channels regulate smooth muscle cell migration, neointimal formation, and oxygen‐induced vascular contraction in rat ductus arteriosus

ObjectiveCa2+ influx through voltage‐dependent Ca2+ channels regulates vascular contraction and remodeling. However, the role of T‐type Ca2+ channels (TCCs) has remained unknown in the ductus arteriosus (DA).Methods and Results 1) α1G, a TCC subtype, was significantly up‐regulated in rat neonatal DA tissues at birth and in DA smooth muscle cells (SMCs) that were exposed to oxygen. α1G was localized predominantly to the region of intimal thickening in fetal DA at term and to the central core of neonatal DA at birth. 2) α1G over expression promoted SMC migration by 164% relative to control (n=7, p&lt;0.01). α1G‐specific siRNAs inhibited SMC migration by 60% relative to negative siRNA (n=8, p&lt;0.01). A highly selective TCC blocker, R(−)‐efonidipine, suppressed SMC migration by 62% relative to control (n=5, p&lt;0.01). 3) A prostaglandin E receptor EP4 agonist potently promoted physiological intimal thickening (Yokoyama et al. J Clin Invest 2006). Intimal‐media ratio of DA stimulated by EP4 was decreased by 60% in the presence of R(−)‐efonidipine (n=5, p&lt;0.01). 4) R(−)‐efonidipine significantly attenuated oxygen‐induced vasoconstriction in a dose‐dependent manner.ConclusionTCC, especially α1G, regulates SMC migration, neointimal formation, and oxygen‐induced vascular contraction in rat DA.

Extracellular Matrix-Mediated Control of Aortic Smooth Muscle Cell Growth and Migration by a Combination of Ascorbic Acid, Lysine, Proline, and Catechins

Extracellular matrix (ECM) function and structure are severely compromised at atherosclerotic lesion sites, contributing to initiation and progression of the disease. This study investigated whether ECM biological properties would be beneficially affected by exposure to nutrients essential for collagen synthesis and posttranslational modification. Confluent layers of human aortic smooth muscle cells (SMC) grown on collagen substrate were cultured in the presence of the tested compounds for 7 to 10 days. Pretreated cells were removed from the ECM surface by differential treatment and replaced with secondary innocent SMC cultures. Secondary SMC growth rate and invasiveness were assayed in standard growth medium. ECM protein composition was assayed immunochemically. ECM produced in the presence of ascorbic acid reduced SMC proliferation in a dose-dependent manner. Plant-derived phenolic extracts expressed different degrees of SMC growth inhibition when present during ECM production. A combination of selected nutrients had a greater effect than did individual components. The ECM deposited by SMC in the presence of ascorbate, lysine, proline, and green tea catechins inhibited SMC migration rate up to 70%. The ECM produced under conditions of chronic essential nutrient deficiency can support proatherosclerotic SMC behavior. A combination of selected nutrients can counteract these adverse effects stronger than individual components.

Antiproliferative effects of 6-anilino-5-chloro-1H-benzo[ d]imidazole-4,7-dione in vascular smooth muscle cells

It has been known that benzimidazol-4,7-diones have antiproliferative activity against various cancer cell lines. Recently, we have also reported that these compounds strongly inhibited the proliferation of vascular smooth muscle cell (SMC) and human umbilical vein endothelial cells (HUVECs). Although benzimidazol-4,7-diones have important biological activities, the molecular mechanism of the compounds in these cells remains to be elucidated. In order to investigate the anti-proliferation mechanism of the compounds in smooth muscle cell, we selected 6-anilino-6-chloro-5-chloro-1 H-benzo{ d}midazole-4,7-dione (BUD-0203) among 12 benzimidazol-4,7-dione derivatives and examined its antiproliferative effects. Phosphorylation of the extracellular-signal regulated kinase (ERK) reached a maximal level at 1 h after treatment with BUD-0203 and was sustained during the examined period. We also observed that phosphorylation of p38 reached a maximal level at 4 h and decreased to control levels after 8 h. These results showed that BUD-0203 sustainedly activated MAP kinase pathways in SMC. However, this compound did not induce cell cycle arrest in G1 or G2 phase in these cells. We also demonstrated that BUD-0203 not only induced apoptosis of SMC, but it also strongly inhibited SMC migration induced by platelet-derived growth factor (PDGF) or serum.Taken together, our experiments indicate that benzimidazol-4,7-diones induce apoptosis of smooth muscle cell via simultaneously prolonged activation of MAP kinase pathways including ERK, p38, and JNK/SAPK, similar with the apoptosis mechanism reported previously.