Platelet-derived growth factor (PDGF): actions and mechanisms in vascular smooth muscle

FXR1 regulates vascular smooth muscle cell cytoskeleton, VSMC contractility, and blood pressure by multiple mechanisms

Appropriate cytoskeletal organization is essential for vascular smooth muscle cell (VSMC) conditions such as hypertension. This study identifies FXR1 as a key protein linking cytoskeletal dynamics with mRNA stability. RNA immunoprecipitation sequencing (RIP-seq) in human VSMCs identifies that FXR1 binds to mRNA associated with cytoskeletal dynamics, and FXR1 depletion decreases their mRNA stability. FXR1 binds and regulates actin polymerization. Mass spectrometry identifies that FXR1 interacts with cytoskeletal proteins, particularly Arp2, a protein crucial for VSMC contraction, and CYFIP1, a WASP family verprolin-homologous protein (WAVE) regulatory complex (WRC) protein that links mRNA processing with actin polymerization. Depletion of FXR1 decreases the cytoskeletal processes of adhesion, migration, contraction, and GTPase activation. Using telemetry, conditional FXR1SMC/SMC mice have decreased blood pressure and an abundance of cytoskeletal-associated transcripts. This indicates that FXR1 is a muscle-enhanced WRC modulatory protein that regulates VSMC cytoskeletal dynamics by regulation of cytoskeletal mRNA stability and actin polymerization and cytoskeletal protein-protein interactions, which can regulate blood pressure.

A patent review on efficient strategies for the total synthesis of pazopanib, regorafenib and lenvatinib as novel anti-angiogenesis receptor tyrosine kinase inhibitors for cancer therapy

Angiogenesis is an important and interesting scientific subject in the area of malignant tumours. Current research importance and interest are directed in connection to blood microvessels in cancer cell proliferation, tumour growth, and metastasis. Tyrosine kinases have been intensely implicated as therapeutic targets that affect the angiogenic process in tumour growth. In the last decades, targeting angiogenesis has led to achievements in the therapy of different carcinomas by different mechanisms, such as the utilization of anti-angiogenic small molecule receptor tyrosine kinase inhibitors. In the current review, we aim to track the advancements in the total synthesis of three receptor tyrosine kinase inhibitors (pazopanib, regorafenib and lenvatinib). This review surveys different synthetic routes for these three approved drugs (pazopanib, regorafenib and lenvatinib) which were previously published as patents (2014-2021). The purity of medicines is a very important factor during manufacturing so we have decided to review the purification process of these anticancer medicines as well. It should be noted that the different patents may have reported some procedures with different yields and purities for the synthesis of desired drug and their intermediates. In order to simplify the understanding of the contents of this review article, only the best results reported in each of these patents are reported for the synthesis of desired drug and their intermediates.

GIT1 is critical for formation of the CD31hiEmcnhi vessel subtype in coupling osteogenesis with angiogenesis via modulating preosteoclasts secretion of PDGF-BB

G protein-coupled receptor kinase 2 interacting protein-1 (GIT1) is a scaffold protein that plays a vital role in bone modeling and remodeling during osteogenesis coupled with angiogenesis. Recent studies have shown that a specialized subset of vascular endothelium strongly positive for CD31 and Endomucin (CD31^hiEmcn^hi) is coupled with anabolic bone formation. Based on our previous finding that GIT1 knockout (GIT1 KO) mice have impaired angiogenesis and bone formation, we hypothesized that GIT1 affects formation of the CD31^hiEmcn^hi vessel subtype. In the current study, GIT1 knockout (GIT1 KO) mice displayed a significant decrease in trabecular bone mass and CD31^hiEmcn^hi vessel number, compared to their wild-type counterparts. In the fracture healing mouse model, GIT1 KO mice contained a lower number of CD31^hiEmcn^hi vessels in fracture callus at days 7 and 14. However, no significant differences in the number of preosteoclasts in bone marrow, trabecular bone and callus in GIT1 KO mice were observed, compared with wild-type mice. Notably, concentrations of serum platelet-derived growth factor-BB(PDGF-BB) secreted by preosteoclasts associated with CD31^hiEmcn^hi vessel formation were lower in GIT1 KO mice. In addition, PDGF-BB-associated expression of phosphorylated extracellular signal-regulated kinase- 1/2 (ERK1/2) and specificity protein 1 (SP1) was significantly decreased in preosteoclasts of GIT1 KO mice. These results collectively suggest that GIT1 is a critical participant in formation of the CD31^hiEmcn^hi vessel subtype, highlighting a novel biologic function of this scaffold protein in preosteoclasts.

Kv channels and vascular smooth muscle cell proliferation

Kv channels are present in virtually all VSMCs and strongly influence contractile responses. However, they are also instrumental in the proliferative, migratory, and secretory functions of synthetic, dedifferentiated VSMCs upon PM. In fact, Kv channels not only contribute to all these processes but also are active players in the phenotypic switch itself. This review is focused on the role(s) of Kv channels in VSMC proliferation, which is one of the best characterized functions of dedifferentiated VSMCs. VSMC proliferation is a complex process requiring specific Kv channels at specific time and locations. Their identification is further complicated by their large diversity and the differences in expression across vascular beds. Of interest, both conserved changes in some Kv channels and vascular bed-specific regulation of others seem to coexist and participate in VSMC proliferation through complementary mechanisms. Such a system will add flexibility to the process while providing the required robustness to preserve this fundamental cellular response.

Platelet communication with the vascular wall: role of platelet-derived microparticles and non-coding RNAs

Platelets play an important role in vascular homeostasis through their interaction with circulating blood cells as well as the vascular wall. Platelet-mediated communication with other cells can take the form of direct cell-cell interactions via membrane receptors or indirectly through the release of different soluble factors stored in their granules as well as through the release of microparticles. The latter carry different proteins and RNAs which are transferred to the target cells. The aim of this review is to discuss the role of platelet-derived factors, adhesion molecules as well as RNAs as mediators of the cross-talk between platelets and the vessel wall.

Phosphatidylinositol 3-Kinase-DNA Methyltransferase 1-miR-1281-Histone Deacetylase 4 Regulatory Axis Mediates Platelet-Derived Growth Factor-Induced Proliferation and Migration of Pulmonary Artery Smooth Muscle Cells

BACKGROUND

Platelet-derived growth factor BB, a potent mitogen of pulmonary artery smooth muscle cells (PASMCs), has been implicated in pulmonary arterial remodeling, which is a key pathogenic feature of pulmonary arterial hypertension. Previous microRNA profiling in platelet-derived growth factor BB-treated PASMCs found a significantly downregulated microRNA, miR-1281, but it has not been associated with any cellular function, and we investigated the possibility.

METHODS AND RESULTS

Real-time quantitative reverse transcription-polymerase chain reaction assay proved that downregulation of miR-1281 was a conserved phenomenon in human and rat PASMCs. Overexpression and inhibition of miR-1281 in PASMCs promoted and suppressed, respectively, the cell proliferation and migration. Bioinformatic prediction and 3'-untranslated region reporter assay identified histone deacetylase 4 to be a direct target of miR-1281. Supporting this, proliferation and migration assay demonstrated the cellular function of histone deacetylase 4 is inversely correlated with that of miR-1281. Mechanistically, it is found that platelet-derived growth factor BB activates the phosphatidylinositol 3-kinase pathway, which then induces the expression of DNA methyltransferase 1, leading to enhanced methylation of a flanking CpG island and repressed miR-1281 expression. Finally, a reduced miR-1281 level was consistently identified in hypoxic PASMCs in vitro, in pulmonary arteries of rats with monocrotaline-induced pulmonary arterial hypertension, and in serum of patients with coronary heart disease-pulmonary arterial hypertension. These data suggest that there may be a diagnostic and therapeutic use for miR-1281.

CONCLUSIONS

Herein, we report a novel regulatory axis, phosphatidylinositol 3-kinase-DNA methyltransferase 1-miR-1281-histone deacetylase 4, integrating multiple epigenetic regulators that participate in platelet-derived growth factor BB-stimulated PASMC proliferation and migration and pulmonary vascular remodeling.

Caveolin 2: a facultative marker of unfavourable prognosis in long-term patency rate of internal thoracic artery grafts used in coronary artery bypass grafting. Preliminary report

OBJECTIVES

Intimal hyperplasia leading to graft failure in patients undergoing coronary artery bypass grafting (CABG) is related to vascular smooth muscle cells (SMCs) proliferation. SMCs respond to a variety of mediators, the most important of which is platelet-derived growth factor (PDGF). The platelet-derived growth factor-induced cellular response has been shown to be mediated by caveolins. The aim of this study was to analyze CAV1-3 expression in internal thoracic artery (ITA) grafts used in CABG and correlate their expression with graft occlusion.

METHODS

Six hundred patients undergoing CABG with the use of ITA grafts between 2008 and 2014 were enrolled into this prospective study. CAV1-3 expression in the ITA grafts was analyzed prior to graft transplantation into the coronary circulation via immunohistochemistry. Estimated caveolins expression pattern was then correlated with the occurrence of ITA graft failure observed within 24-months of surgery.

RESULTS

Thirty-four patients developed ITA graft failure (subgroup A) and 566 study participants presented no adverse events (subgroup B). CAV1 and CAV3 expression levels in SMCs of the tunica media of the ITA grafts did not differ between the study subgroups and were not associated with the risk of graft failure. CAV2 was expressed within SMCs of the ITA grafts in 94.1% of the patients from subgroup A and 2.5% from subgroup B, and its expression was associated with ITA graft occlusion observed within 24-months after CABG.

CONCLUSIONS

CAV2 expression in SMCs of the tunica media in autologous ITA transplants might indicate the risk of graft failure.

Autologous blood preparations rich in platelets, fibrin and growth factors

OBJECTIVES

Bone regeneration is often needed prior to dental implant treatment due to the lack of adequate quantity and quality after infectious diseases. The greatest regenerative power was obtained with autologous tissue, primarily the bone alive, taken from the same site or adjacent sites, up to the use centrifugation of blood with the selection of the parts with the greatest potential regenerative. In fact, various techniques and technologies were chronologically successive to cope with an ever better preparation of these concentrates of blood. Our aim is to review these advances and discuss the ways in which platelet concentrates may provide such unexpected beneficial therapeutic effects.

METHODS

The research has been carried out in the MEDLINE and Cochrane Central Register of Controlled Trials database by choosing keywords as "platelet rich plasma", "platelet rich fibrin", "platelet growth factors", and "bone regeneration" and "dentistry".

RESULTS

Autologous platelet rich plasma is a safe and low cost procedure to deliver growth factors for bone and soft tissue healing.

CONCLUSION

The great heterogeneity of clinical outcomes can be explained by the different PRP products with qualitative and quantitative difference among substance.

The Role of Platelet-Derived Growth Factor Receptor in Early Brain Injury Following Subarachnoid Hemorrhage

OBJECTIVE

This study aims to observe encephaledema and cell apoptosis in rats following subarachnoid hemorrhage (SAH) and to explore the mechanism of platelet-derived growth factor receptor (PDGFR) in the development of early brain injury (EBI).

METHODS

Adult and male Sprague-Dawley rats were randomly divided into 4 groups: sham operation, SAH, SAH + imatinib, and SAH + platelet-derived growth factor-BB (PDGF-BB). SAH model was established using intravascular silk puncture of the internal carotid artery crotch. The SAH + imatinib group was treated with intraperitoneal injection of imatinib 1 hour before establishing the model. The SAH + PDGF-BB group was administered with intracerebroventricular injection of PDGF-BB 1 hour before establishing the model. The mortality, encephaledema, and nerve functional scoring were observed after 24 hours in all groups. The expression of caspase-3 in hippocampus was tested by reverse transcription polymerase chain reaction and Western blotting.

RESULTS

Mortality and encephaledema were the highest in the SAH + PDGF-BB group, which were alleviated when the rats were injected with imatinib (P < .01).

CONCLUSION

PDGFR may participate in the pathogenesis of EBI following SAH. The antagonist of PDGFR, imatinib, can reduce brain damage to some degree.

meso-Dihydroguaiaretic acid attenuates airway inflammation and mucus hypersecretion in an ovalbumin-induced murine model of asthma

meso-Dihydroguaiaretic acid (MDGA), which is a dibenzylbutane lignin isolated from the ethyl acetate fraction of Saururus chinensis, has various biological activities, including anti-oxidative, anti-inflammatory, anti-bacterial, and neuroprotective effects. However, no report has examined the potential anti-asthmatic activity of MDGA. In this study, we evaluated the protective effects of MDGA on asthmatic responses, particularly airway inflammation and mucus hypersecretion in an ovalbumin (OVA)-induced murine model of asthma. Intragastric administration of MDGA significantly lowered the productions of interleukin (IL)-4, IL-5, IL-13, tumor necrosis-α (TNF-α), eotaxin, monocyte chemoattractant protein-1 (MCP-1), vascular cell adhesion molecule-1 (VCAM-1), and immunoglobulin (Ig)E in bronchoalveolar lavage fluid (BALF), plasma, or lung tissues. Histological studies showed that MDGA inhibited OVA-induced inflammatory cell infiltration and mucus production in the respiratory tract. Moreover, MDGA markedly attenuated the OVA-induced activations of nuclear factor kappa B (NF-κB), extracellular-signal-regulated kinases 1/2 (ERK1/2), and p38 mitogen-activated protein kinase (p38 MAPK). Together, these results suggest that MDGA effectively inhibits airway inflammation and mucus hypersecretion by downregulating the levels of T helper 2 (Th2) cytokines, chemokines, and adhesion molecules, and inhibiting the activations of NF-κB and MAPKs.

Atherosclerosis: a chronic inflammatory disease mediated by mast cells

Inflammation is a process that plays an important role in the initiation and progression of atherosclerosis and immune disease, involving multiple cell types, including macrophages, T-lymphocytes, endothelial cells, smooth muscle cells and mast cells. The fundamental damage of atherosclerosis is the atheromatous or fibro-fatty plaque which is a lesion that causes several diseases. In atherosclerosis the innate immune response, which involves macrophages, is initiated by the arterial endothelial cells which respond to modified lipoproteins and lead to Th1 cell subset activation and generation of inflammatory cytokines and chemoattractant chemokines. Other immune cells, such as CD4+ T inflammatory cells, which play a critical role in the development and progression of atherosclerosis, and regulatory T cells [Treg], which have a protective effect on the development of atherosclerosis are involved. Considerable evidence indicates that mast cells and their products play a key role in inflammation and atherosclerosis. Activated mast cells can have detrimental effects, provoking matrix degradation, apoptosis, and enhancement as well as recruitment of inflammatory cells, which actively contributes to atherosclerosis and plaque formation. Here we discuss the relationship between atherosclerosis, inflammation and mast cells.

Healing arterial ulcers: Endothelial lining regeneration upon vascular denudation injury

Thrombosis and restenosis are the most prevalent late complications of coronary artery stenting. Current standards of clinical care focus on prevention of smooth muscle cell proliferation by the use of drug-eluting stents able to release anti-proliferative drugs. Unfortunately, these drugs also block endothelial cell proliferation and, in this manner, prevent recovery of endothelial cell coverage. Continued lack of endothelial repair leaves the root cause of thrombosis and restenosis unchanged, creating a vicious cycle where drug-mediated prevention of restenosis simultaneously implies promotion of thrombosis. In this issue of Vascular Pharmacology, Hussner and colleagues provide in vitro evidence and a mechanistic basis for the use of atorvastatin in stents as a way to bypass this roadblock. Here we review the pathological mechanisms and therapeutic approaches to restore flow in occluded arteries. We argue that rational design of drug eluting stents should focus on specific inhibition of smooth muscle cell proliferation with concurrent stimulation of endothelial regeneration. We comment on the current poor understanding of the cellular and molecular regulation of endothelial cell proliferation in the context of a functional artery, and on the pitfalls of extrapolating from the well-studied process of neovascularization by sprouting vessel formation.

Disruption of miR-29 Leads to Aberrant Differentiation of Smooth Muscle Cells Selectively Associated with Distal Lung Vasculature

Differentiation of lung vascular smooth muscle cells (vSMCs) is tightly regulated during development or in response to challenges in a vessel specific manner. Aberrant vSMCs specifically associated with distal pulmonary arteries have been implicated in the pathogenesis of respiratory diseases, such as pulmonary arterial hypertension (PAH), a progressive and fatal disease, with no effective treatment. Therefore, it is highly relevant to understand the underlying mechanisms of lung vSMC differentiation. miRNAs are known to play critical roles in vSMC maturation and function of systemic vessels; however, little is known regarding the role of miRNAs in lung vSMCs. Here, we report that miR-29 family members are the most abundant miRNAs in adult mouse lungs. Moreover, high levels of miR-29 expression are selectively associated with vSMCs of distal vessels in both mouse and human lungs. Furthermore, we have shown that disruption of miR-29 in vivo leads to immature/synthetic vSMC phenotype specifically associated with distal lung vasculature, at least partially due to the derepression of KLF4, components of the PDGF pathway and ECM-related genes associated with synthetic phenotype. Moreover, we found that expression of FBXO32 in vSMCs is significantly upregulated in the distal vasculature of miR-29 null lungs. This indicates a potential important role of miR-29 in smooth muscle cell function by regulating FBXO32 and SMC protein degradation. These results are strongly supported by findings of a cell autonomous role of endogenous miR-29 in promoting SMC differentiation in vitro. Together, our findings suggested a vessel specific role of miR-29 in vSMC differentiation and function by targeting several key negative regulators.

The pathogenesis of some vascular diseases, such as PAH is selectively associated with aberrant differentiation and proliferation of vSMCs of distal arteries. While significant progresses have been made in understanding the core mechanism of differentiation and proliferation of vSMCs, little is known regarding vessel specific regulations. By investigating the expression and function of miR-29 in vivo, we found a vessel selective enriched expression and function of miR-29 during mouse lung development. Interestingly, disruption of miR-29 results in defects in vSMCs differentiation of distal vessels, reminiscent of vSMC phenotype observed in the early stage of PAH in which immature/synthetic vSMCs of distal arteries failed to differentiate and were unable to tune down the expression of collagens and other extracellular-related genes. This is the first evidence that miR-29 selectively regulates vSMCs differentiation and vessel wall formation. Future implications are to study the expression and function of miR-29 in human pulmonary vascular diseases, which might lead to establishing miR-29 as a therapeutic target for disease intervention.

Determining the Effect of Preparation and Storage: An Effort to Streamline Platelet Components as a Source of Growth Factors for Clinical Application

BACKGROUND

In the present study, different methods for preparation of platelet-rich plasma (PRP) are investigated in order to standardize the component in terms of growth factor content. The effects of concentration technique and storage duration are also analyzed.

METHODS

PRP was collected from 40 donors by plateletpheresis as well as by the buffy coat and tube method. Concentration of growth factors was performed using double freeze thaw- and CaCl2-induced degranulation techniques. Growth factor estimation was performed using ELISA.

RESULTS

The levels of growth factors were highest in PRP from buffy coat, moderately lower in plasma gained by plateletpheresis and lowest in that obtained by the tube method. Mean levels of platelet-derived growth factors (PDGF) AB and BB are significantly higher when CaCl2 was used for concentrating the growth factors. The mean levels of transforming growth factor β1 and insulin-like growth factor I were higher when applying the double freeze thaw technique. There was a substantial decline in the levels of growth factors during storage.

CONCLUSION

The buffy coat method is suitable as preparation method for PRP in most settings. The double freeze thaw technique is better suited as concentration technique as it causes lysis of both platelets and white blood cells for releasing growth factors and is easier to perform. Growth factors are not stable in plasma, thus PRP should be frozen immediately after preparation.

Kv1.3 channels modulate human vascular smooth muscle cells proliferation independently of mTOR signaling pathway

Phenotypic modulation (PM) of vascular smooth muscle cells (VSMCs) is central to the process of intimal hyperplasia which constitutes a common pathological lesion in occlusive vascular diseases. Changes in the functional expression of Kv1.5 and Kv1.3 currents upon PM in mice VSMCs have been found to contribute to cell migration and proliferation. Using human VSMCs from vessels in which unwanted remodeling is a relevant clinical complication, we explored the contribution of the Kv1.5 to Kv1.3 switch to PM. Changes in the expression and the functional contribution of Kv1.3 and Kv1.5 channels were studied in contractile and proliferating VSMCs obtained from human donors. Both a Kv1.5 to Kv1.3 switch upon PM and an anti-proliferative effect of Kv1.3 blockers on PDGF-induced proliferation were observed in all vascular beds studied. When investigating the signaling pathways modulated by the blockade of Kv1.3 channels, we found that anti-proliferative effects of Kv1.3 blockers on human coronary artery VSMCs were occluded by selective inhibition of MEK/ERK and PLCγ signaling pathways, but were unaffected upon blockade of PI3K/mTOR pathway. The temporal course of the anti-proliferative effects of Kv1.3 blockers indicates that they have a role in the late signaling events essential for the mitogenic response to growth factors. These findings establish the involvement of Kv1.3 channels in the PM of human VSMCs. Moreover, as current therapies to prevent restenosis rely on mTOR blockers, our results provide the basis for the development of novel, more specific therapies.

Hydrogel nanoparticle harvesting of plasma or urine for detecting low abundance proteins

Novel biomarker discovery plays a crucial role in providing more sensitive and specific disease detection. Unfortunately many low-abundance biomarkers that exist in biological fluids cannot be easily detected with mass spectrometry or immunoassays because they are present in very low concentration, are labile, and are often masked by high-abundance proteins such as albumin or immunoglobulin. Bait containing poly(N-isopropylacrylamide) (NIPAm) based nanoparticles are able to overcome these physiological barriers. In one step they are able to capture, concentrate and preserve biomarkers from body fluids. Low-molecular weight analytes enter the core of the nanoparticle and are captured by different organic chemical dyes, which act as high affinity protein baits. The nanoparticles are able to concentrate the proteins of interest by several orders of magnitude. This concentration factor is sufficient to increase the protein level such that the proteins are within the detection limit of current mass spectrometers, western blotting, and immunoassays. Nanoparticles can be incubated with a plethora of biological fluids and they are able to greatly enrich the concentration of low-molecular weight proteins and peptides while excluding albumin and other high-molecular weight proteins. Our data show that a 10,000 fold amplification in the concentration of a particular analyte can be achieved, enabling mass spectrometry and immunoassays to detect previously undetectable biomarkers.

TGFBR1 is required for mouse myometrial development

The smooth muscle layer of the uterus (ie, myometrium) is critical for a successful pregnancy and labor. We have shown that the conditional deletion of TGFβ type 1 receptor (TGFBR1) in the female reproductive tract leads to remarkable smooth muscle defects. This study was aimed at defining the cellular and molecular basis of the myometrial defects. We found that TGFBR1 is required for myometrial configuration and formation during early postnatal uterine development. Despite the well-established role of TGFβ signaling in vascular smooth muscle cell differentiation, the majority of smooth muscle genes were expressed in Tgfbr1 conditional knockout (cKO) uteri at similar levels as controls during postnatal uterine development, coinciding with the presence but abnormal distribution of proteins for select smooth muscle markers. Importantly, the uteri of these mice had impaired synthesis of key extracellular matrix proteins and dysregulated expression of platelet-derived growth factors. Furthermore, platelet-derived growth factors induced the migration of uterine stromal cells from both control and Tgfbr1 cKO mice in vitro. Our results suggest that the myometrial defects in Tgfbr1 cKO mice may not directly arise from an intrinsic deficiency in uterine smooth muscle cell differentiation but are linked to the impaired production of key extracellular matrix components and abnormal uterine cell migration during a critical time window of postnatal uterine development. These findings will potentially aid in the design of novel therapies for reproductive disorders associated with myometrial defects.

Pelargonidin attenuates PDGF-BB-induced aortic smooth muscle cell proliferation and migration by direct inhibition of focal adhesion kinase

Pelargonidin is a natural red pigment found in fruits and vegetables, and has been reported to exhibit various effects potentially beneficial for human health. However, the possible preventive effects of pelargonidin toward atherosclerosis and mechanisms involved have not been investigated to date. Here, we compared the effects of pelargonidin and its glucoside-conjugated form, pelargonidin-3-glucoside (P3G), on proliferation and migration induced by platelet-derived growth factor (PDGF)-BB in human aortic smooth muscle cells (HASMCs). Pelargonidin, but not P3G, exhibited strong inhibitory effects against PDGF-BB-induced HASMC proliferation and migration, while suppressing PDGF-BB-induced ex vivo rat aortic ring sprouting. Immunoblot analysis revealed that pelargonidin inhibited PDGF-BB-induced phosphorylation of focal adhesion kinase (FAK) as well as F-actin reduction, whereas Src, mitogen-activated protein kinases (MAPKs) and Akt phosphorylation status were not altered. We also observed that the anti-proliferative and migratory effects of both pelargonidin and P3G corresponded with the extent of FAK inhibition. Both in vitro and ex vivo pull-down assays revealed that pelargonidin binds directly with FAK in an adenosine triphosphate-competitive manner, suggesting that FAK could be a molecular target of pelargonidin. Interestingly, pelargonidin did not exhibit inhibitory effects on the proliferation, migration or FAK phosphorylation of human umbilical vein endothelial cells (HUVECs). Taken together, our results suggest that pelargonidin exhibits potential preventive effects toward atherosclerosis through the attenuation of HASMC proliferation and migration, as well as aortic sprouting via the direct inhibition of FAK activity.

Chitosan nanoparticle carrying small interfering RNA to platelet-derived growth factor B mRNA inhibits proliferation of smooth muscle cells in rabbit injured arteries

The purpose of this study was to elucidate the transfection of chitosan nanoparticle carrying small interfering RNA against platelet-derived growth factor B (PDGF-B) to inhibit the expression of PDGF-B mRNA and proliferation of smooth muscle cells. A rabbit iliac artery injury model was constructed. A small interfering RNA (siRNA) against PDGF-B mRNA expression vector was constructed and packaged by chitosan nanoparticle to transfect into the vascular smooth muscle cells (vSMCs) of balloon catheter-injured rabbit iliac artery wall, using a therapeutic ultrasound for the gene delivery. The experiment was divided into two groups: experimental group, denudation and nano-PDGF-B siRNA treated, and only single denudation as control. Effects of the siRNA on the expressions of proliferating cell nuclear antigen (PCNA) and PDGF-B mRNA by vSMCs and the proliferation of vSMCs were observed with the methods of routine pathological, immunohistochemical staining, in situ hybridization and morphometry. The nano siRNA against PDGF-B was successfully transfected. The nano siRNA significantly inhibited the expressions of PCNA and PDGF-B mRNA in intimal vSMCs. The local intimal thickness and area were also reduced remarkably. In conclusion, transfection of chitosan nanoparticle carrying siRNA against PDGF-B mRNA could inhibit proliferation of vSMCs in the rabbit iliac artery injury model.

Inhibitory effects of resveratrol on PDGF-BB-induced retinal pigment epithelial cell migration via PDGFRβ, PI3K/Akt and MAPK pathways

Purpose

In diseases such as proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy, and age-related macular degeneration, retinal pigment epithelial (RPE) cells proliferate and migrate. Moreover, platelet-derived growth factor (PDGF) has been shown to enhance proliferation and migration of RPE cells in PVR. Even resveratrol can suppress the migration and adhesion of many cell types, its effects on RPE cell migration and adhesion remain unknown. In this study, we investigated the inhibitory effects of resveratrol on RPE cell migration induced by PDGF-BB, an isoform of PDGF, and adhesion to fibronectin, a major ECM component of PVR tissue.

Methods

The migration of RPE cells was assessed by an electric cell-substrate impedance sensing migration assay and a Transwell migration assay. A cell viability assay was used to determine the viability of resveratrol treated-cells. The cell adhesion to fibronectin was examined by an adhesion assay. The interactions of resveratrol with PDGF-BB were analyzed by a dot binding assay. The PDGF-BB-induced signaling pathways were determined by western blotting and scratch wound healing assay.

Results

Resveratrol inhibited PDGF-BB-induced RPE cell migration in a dose-dependent manner, but showed no effects on ARPE19 cell adhesion to fibronectin. The cell viability assay showed no cytotoxicity of resveratrol on RPE cells and the dot binding assay revealed no direct interactions of resveratrol with PDGF-BB. Inhibitory effects of resveratrol on PDGF-BB-induced platelet-derived growth factor receptor β (PDGFRβ) and tyrosine phosphorylation and the underlying pathways of PI3K/Akt, ERK and p38 activation were found; however, resveratrol and PDGF-BB showed no effects on PDGFRα and JNK activation. Scratch wound healing assay demonstrated resveratrol and the specific inhibitors of PDGFR, PI3K, MEK or p38 suppressed PDGF-BB-induced cell migration.

Conclusions

These results indicate that resveratrol is an effective inhibitor of PDGF-BB-induced RPE cell migration via PDGFRβ, PI3K/Akt and MAPK pathways, but has no effects on the RPE cell adhesion to fibronectin.

Camptothecin inhibits platelet-derived growth factor-BB-induced proliferation of rat aortic vascular smooth muscle cells through inhibition of PI3K/Akt signaling pathway

The abnormal proliferation of vascular smooth muscle cells (VSMCs) in arterial wall is a major cause of vascular disorders such as atherosclerosis and restenosis after angioplasty. In this study, we investigated not only the inhibitory effects of camptothecin (CPT) on PDGF-BB-induced VSMC proliferation, but also its molecular mechanism of this inhibition. CPT significantly inhibited proliferation with IC50 value of 0.58 μM and the DNA synthesis of PDGF-BB-stimulated VSMCs in a dose-dependent manner (0.5-2 μM ) without any cytotoxicity. CPT induced the cell cycle arrest at G0/G1 phase. Also, CPT decreased the expressions of G0/G1-specific regulatory proteins including cyclin-dependent kinase (CDK)2, cyclin D1 and PCNA in PDGF-BB-stimulated VSMCs. Pre-incubation of VSMCs with CPT significantly inhibited PDGF-BB-induced Akt activation, whereas CPT did not affect PDGF-receptor beta phosphorylation, extracellular signal-regulated kinase (ERK) 1/2 phosphorylation and phospholipase C (PLC)-γ1 phosphorylation in PDGF-BB signaling pathway. Our data showed that CPT pre-treatment inhibited VSMC proliferation, and that the inhibitory effect of CPT was enhanced by LY294002, a PI3K inhibitor, on PDGF-BB-induced VSMC proliferation. In addition, inhibiting the PI3K/Akt pathway by LY294002 significantly enhanced the suppression of PCNA expression and Akt activation by CPT. These results suggest that the anti-proliferative activity of CPT is mediated in part by downregulating the PI3K/Akt signaling pathway.

Potential role of vascular smooth muscle cell-like progenitor cell therapy in the suppression of experimental abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) are a growing problem worldwide, yet there is no known medical therapy. The pathogenesis involves degradation of the elastic lamina by two combined mechanisms: increased degradation of elastin by matrix metalloproteinases (MMP) and decreased formation of elastin due to apoptosis of vascular smooth muscle cells (VSMC). In this study, we set out to examine the potential role of stem cells in the attenuation of AAA formation by inhibition of these pathogenetic mechanisms. Muscle-derived stem cells from murine skeletal muscles were isolated and stimulated with PDGF-BB in vitro for differentiation to VSMC-like progenitor cells (VSMC-PC). These cells were implanted in to elastase-induced AAAs in rats. The cell therapy group had decreased rate of aneurysm formation compared to control, and MMP expression at the genetic, protein and enzymatic level were also significantly decreased. Furthermore, direct implantation of VSMC-PCs in the intima of harvested aortas was visualized under immunofluorescent staining, suggesting that these cells were responsible for the inhibition of MMPs and consequent attenuation of AAA formation. These results show a promising role of stem cell therapy for the treatment of AAAs, and with further studies, may be able to reach clinical significance.

Antirestenosis effect of butein in the neointima formation progression

The development of restenosis involves migration and hyperproliferation of vascular smooth muscle cells (VSMCs). Platelet-derived growth factor (PDGF) is one of the major factors. Butein modulates inflammatory pathways and affects the proliferation and invasion of the tumor. We investigated the hypothesis that butein might prevent the restenosis process via a similar pathway. Our results demonstrated that butein inhibited PDGF-induced VSMC proliferation and migration as determined by BrdU proliferation and two-dimensional migration scratch assay. Butein also concentration-dependently repressed PDGF-induced phosphorylation of PDGF-receptor β, mitogen-activated protein kinases, phosphoinositide 3-kinase/Akt, and phopholipase Cγ/c-Src in VSMCs. In addition, in vivo results showed that butein attenuated neointima formation in balloon-injured rat carotid arteries. These results indicate that butein may inhibit PDGF-induced VSMC proliferation and migration, resulting in attenuation of neointima formation after percutaneous transluminal coronary angioplasty. Our study demonstrates for the first time that systemic administration of butein is able to reduce neointima formation after vascular injury.

Antirestenotic mechanisms of everolimus on human coronary artery smooth muscle cells: inhibition of human coronary artery smooth muscle cell proliferation, but not migration

Everolimus, a pharmaceutical component of drug-eluting stents, inhibits coronary vessel restenosis, but the antirestenotic mechanisms of action remain unclear. Here, we describe the effects of everolimus on key contributors to vessel restenosis, smooth muscle cell proliferation, and migration. In a dose-dependent fashion, everolimus reduced human coronary artery smooth muscle cell (HCASMC) proliferation without toxicity in a bimodal fashion, with accentuated potency occurring at 10 μM. Everolimus arrested the majority of HCASMCs in G1-phase, whereas it reduced the fraction of cells in S-phase at doses that inhibited DNA synthesis (bromodeoxyuridine incorporation). Consistent with this, Western blotting demonstrated that everolimus reduced activation and expression of G1-phase cell cycle progression factors, including p70S6K and cyclin D, respectively, decreased levels of proliferating cell nuclear antigen, and attenuated growth factor/serum-induced phosphorylation of the cell cycle phase transition intermediate, retinoblastoma protein. Everolimus did not, however, affect HCASMC migration. These observations suggest that everolimus acts as an antiproliferative, but not antimigratory, compound to account for at least some of the clinical efficacy exhibited by this drug as an antirestenotic agent. Moreover, everolimus-induced inhibition of the mammalian target of rapamycin complex 1 and regulation of cyclin-mediated cell cycle progression actions likely account for the antiproliferative effects of this compound on HCASMCs.

A naturally occurring carotenoid, lutein, reduces PDGF and H₂O₂ signaling and compromised migration in cultured vascular smooth muscle cells

Background

Platelet-derived growth factor (PDGF) is a potent stimulator of growth and motility of vascular smooth muscle cells (VSMCs). Abnormalities of PDGF/PDGF receptor (PDGFR) are thought to contribute to vascular diseases and malignancy. We previously showed that a carotenoid, lycopene, can directly bind to PDGF and affect its related functions in VSMCs. In this study we examined the effect of the other naturally occurring carotenoid, lutein, on PDGF signaling and migration in VSMCs.

Methods

Western blotting was performed to examine PDGF and H₂O₂ signaling. Flowcytometry was used to determine PDGF binding to VSMCs. Fluorescence microscopy was performed to examine intracellular ROS production. Modified Boyden chamber system (Transwell apparatus) was used for migration assay.

Results

Lutein reduced PDGF signaling, including phosphorylation of PDGFR-β and its downstream protein kinases/enzymes such as phospholipase C-γ, Akt, and mitogen-activated protein kinases (MAPKs). Although lutein possesses a similar structure to lycopene, it was striking that lutein inhibited PDGF signaling through a different way from lycopene in VSMCs. Unlike lycopene, lutein not only interacted with (bound to) PDGF but also interfered with cellular components. This was evidenced that preincubation of PDGF with lutein and treatment of VSMCs with lutein followed by removing of lutein compromised PDGF-induced signaling. Lutein reduced PDGF-induced intracellular reactive oxygen species (ROS) production and attenuated ROS- (H₂O₂-) induced ERK1/2 and p38 MAPK activation. A further analysis indicated lutein could inhibit a higher concentration of H₂O₂-induced PDGFR signaling, which is known to act through an oxidative inhibition of protein tyrosine phosphatase. Finally, we showed that lutein functionally inhibited PDGF-induced VSMC migration, whereas its stereo-isomer zeaxanthin did not, revealing a special action of lutein on VSMCs.

Conclusions

Our study reveals a differential action mechanism of lutein from other reported caroteinoids and suggests a possible beneficial effect of lutein but not zeaxanthin on prevention of vascular diseases.

Inhibitory effects of docetaxel on platelet-derived growth factor (PDGF)-BB-induced proliferation of vascular smooth muscle cells through blocking PDGF-receptor β phosphorylation

The abnormal proliferation of vascular smooth muscle cells (VSMCs) in arterial wall is an important pathogenic factor for vascular disorders such as atherosclerosis and restenosis after angioplasty. The present study was designed to investigate the inhibitory effects of docetaxel on VSMC proliferation, as well as the molecular mechanism of this inhibition. Docetaxel at 10, 20 and 40 µM significantly inhibited both the proliferation and the DNA synthesis of fetal bovine serum (FBS)- and platelet-derived growth factor (PDGF)-BB-stimulated VSMCs in a concentration-dependent manner. In accordance with these findings, docetaxel blocked the FBS- and PDGF-BB-induced progression of synchronized cells through the G0/G1 phase of the cell cycle. Docetaxel also decreased the expressions of cell cycle-related proteins, including cyclin-dependent kinase (CDK) 2, cyclin E, CDK4, cyclin D1, retinoblastoma protein, and proliferative cell nuclear antigen in PDGF-BB-stimulated VSMCs. Docetaxel significantly inhibited the phosphorylation of extracellular signal-regulated kinase 1/2, Akt, and phospholipase C-γ1, downstream molecule in the PDGF-BB signaling pathway. Docetaxel suppressed the phosphorylation of PDGF receptor (PDGF-R) β, the upstream molecule in PDGF-BB signaling cascade, suggesting that the inhibitory effect of docetaxel on the proliferation of VSMCs may occur by blocking PDGF-Rβ phosphorylation. Thus, docetaxel may be a potential antiproliferative agent for the treatment of atherosclerosis and angioplasty restenosis.[Supplementary Figures: available only at http://dx.doi.org/10.1254/jphs.10276FP].

Vitisin B, a resveratrol tetramer, inhibits migration through inhibition of PDGF signaling and enhancement of cell adhesiveness in cultured vascular smooth muscle cells

Vascular smooth muscle cells (VSMCs) play an important role in normal vessel formation and in the development and progression of cardiovascular diseases. Grape plants contain resveratrol monomer and oligomers and drinking of wine made from grape has been linked to "French Paradox". In this study we evaluated the effect of vitisin B, a resveratrol tetramer, on VSMC behaviors. Vitisin B inhibited basal and PDGF-induced VSMC migration. Strikingly, it did not inhibit VSMC proliferation but inversely enhanced cell cycle progression and proliferation. Among the tested resveratrol oligomers, vitisin B showed an excellent inhibitory activity and selectivity on PDGF signaling. The anti-migratory effect by vitisin B was due to direct inhibition on PDGF signaling but was independent of interference with PDGF binding to VSMCs. Moreover, the enhanced VSMC adhesiveness to matrix contributed to the anti-migratory effect by vitisin B. Fluorescence microscopy revealed an enhanced reorganization of actin cytoskeleton and redistribution of activated focal adhesion proteins from cytosol to the peripheral edge of the cell membrane. This was confirmed by the observation that enhanced adhesiveness was repressed by the Src inhibitor. Finally, among the effects elicited by vitisin B, only the inhibitory effect toward basal migration was partially through estrogen receptor activation. We have demonstrated here that a resveratrol tetramer exhibited dual but opposite actions on VSMCs, one is to inhibit VSMC migration and the other is to promote VSMC proliferation. The anti-migratory effect was through a potent inhibition on PDGF signaling and novel enhancement on cell adhesion.

A Novel Multiwell Device to Study Vascular Smooth Muscle Cell Responses Under Cyclic Strain

Vascular smooth muscle cells (VSMCs) are constantly exposed to cyclic stretch in the body, which makes it beneficial to study the effects of cyclic stretch on VSMCs. In this study, we developed a poly(dimethyl siloxane) (PDMS) compact six-well device that can be used to study the combined effect of cyclic strain and various growth factors on cultured VSMCs. Cell adhesion, alignment, and proliferation under 10% or 20% cyclic strain at 1 Hz were studied using this surface-enhanced PDMS device. The combined effects of cyclic strain with either transforming growth factor-β, vascular endothelial growth factor, fibroblast growth factor, or epidermal growth factor on VSMC proliferation was also examined. Results showed that VSMCs adhered well on the surface-enhanced multiwell device and they aligned perpendicularly to the direction of the cyclic strain. Cell proliferation was inhibited by 10% cyclic strain at 1 Hz compared with static control. The mitogenic effects of the growth factor were less potent under either 10% or 20% cyclic strain. With simple modification to accommodate more wells, this device could potentially be a useful tool for more economical, high throughput screening application.

Sequential delivery of basic fibroblast growth factor and platelet-derived growth factor for angiogenesis

An externally regulated delivery model that permits temporal separation of multiple angiogenic factors was used for the delivery of basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF). While bFGF plays a significant role in the sprouting of new capillaries, PDGF plays a role in the recruitment of mural cells, which stabilize neovessels. However, these two factors have been shown to inhibit each other, when presented together. Using the externally regulated model, sequential delivery of bFGF and PDGF led to not only increased endothelial cell migration, but also endothelial cell and vascular pericyte colocalization. More importantly, this delivery strategy was able to induce red blood cell-filled neovessels, suggesting integration of angiogenesis with the existing vasculature.

Zeaxanthin inhibits PDGF-BB-induced migration in human dermal fibroblasts

Zeaxanthin is the dihydroxy carotenoid and is distributed in our daily foods. Various natural carotenoids, including zeaxanthin, have been shown to inhibit proliferation of several types of cancer cells, but available data on the effect of zeaxanthin on skin fibroblasts and melanoma cells are limited. Platelet-derived growth factor (PDGF) functions as a chemotactic factor for dermal fibroblasts and plays an important role in the progression of melanoma. In this study, we investigated the effects of zeaxanthin on the migration of skin fibroblasts induced by PDGF-BB and melanoma cells. We demonstrated that zeaxanthin inhibited PDGF-BB-induced skin fibroblast migration on collagen and gelatin by a modified Boyden chamber system. The electric cell-substrate impedance sensing (ECIS) method also showed similar inhibitory effects of zeaxanthin on the migration of fibroblasts. In functional studies, zeaxanthin decreased melanoma-induced fibroblast migration in a non-contact coculture system and also the migration stimulated by melanoma-derived conditioned medium. Further analysis showed that zeaxanthin attenuated PDGF-BB and melanoma-conditioned medium induced phosphorylation of PDGFR-beta and MAP kinase in a concentration-dependent manner in human skin fibroblasts. However, these effects did not result from direct interaction of zeaxanthin with PDGF-BB. Thus, our results provide the first evidence showing that zeaxanthin is an effective inhibitor of migration of stromal fibroblasts induced by PDGF-BB and melanoma cells and this effect may further support its antitumor potential.

The role of Src homology 2 containing protein tyrosine phosphatase 2 in vascular smooth muscle cell migration and proliferation

Vascular smooth muscle cells (VSMCs) perform essential smooth muscle contractile and synthetic functions including migration, differentiation and proliferation under physiological and pathological conditions. In response to pathological stimuli, VMSCs undergo phenotypic change resulting in abnormal migration and proliferation, which may contribute to a "pathogenesis-like" atherosclerosis. Intracellular signaling mechanisms governing this phenotypic switch are of great significance not only for better understanding of atherosclerotic plaque formation but also for strategy for pertinent therapeutic remedies. Src Homology 2 Containing Protein Tyrosine Phosphatase 2 (SHP2) is a ubiquitous tyrosine phosphatase containing Src Homology 2 domains which plays major biological functions in response to various growth factors, hormones or cytokines. In particular, SHP2 is implicated in cell signaling pathways controlling cell cycle progression, growth and migration. In this review we will mainly discuss the recent literature demonstrating the role of SHP2 in VSMC migration and proliferation.

Pterostilbene, a natural dimethylated analog of resveratrol, inhibits rat aortic vascular smooth muscle cell proliferation by blocking Akt-dependent pathway

Vascular smooth muscle cells (VSMCs) are the main cellular component in the arterial wall, and abnormal proliferation of VSMCs plays a central role in the pathogenesis of atherosclerosis and restenosis after angioplasty, and possibly in the development of hypertension. Pterostilbene, a natural dimethylated analog of resveratrol, is known to have diverse pharmacological activities including anti-cancer, anti-inflammation and anti-oxidant activities. The present study was designed to investigate the effects of pterostilbene on platelet-derived growth factor (PDGF)-BB-induced VSMCs proliferation as well as the molecular mechanisms of the antiproliferative effects. The cell growth of VSMCs was determined by cell counting and [(3)H]thymidine incorporation assays. Pterostilbene significantly inhibited the DNA synthesis and proliferation of PDGF-BB-stimulated VSMCs in a concentration-dependent manner. The inhibition percentages of pterostilbene at 1, 3 and 5microM to VSMCs proliferation were 68.5, 80.7 and 94.6%, respectively. The DNA synthesis of pterostilbene at 1, 3 and 5microM in VSMCs was inhibited by 47.4, 76.7 and 100%, respectively. Pterostilbene inhibited the PDGF-BB-stimulated phosphorylation of Akt kinase. However, pterostilbene did not change the expression of extracellular signal-related kinase (ERK) 1/2, PLCgamma1, phosphatidylinositol (PI)3 kinase and PDGF-Rbeta phosphorylation. In addition, pterostilbene down-regulated the cell cycle-related proteins including the expression of cyclin-dependent kinase (CDK) 2, cyclin E, CDK4, cyclin D1, retinoblastoma (Rb) proteins and proliferative cell nuclear antigen (PCNA). These findings suggest that the inhibition of pterostilbene to the cell proliferation and DNA synthesis of PDGF-BB-stimulated VSMCs may be mediated by the suppression of Akt kinase. Furthermore, pterostilbene may be a potential anti-proliferative agent for the treatment of atherosclerosis and angioplasty restenosis.

Lycopene binding compromised PDGF-AA/-AB signaling and migration in smooth muscle cells and fibroblasts: prediction of the possible lycopene binding site within PDGF

Platelet-derived growth factor (PDGF) is a potent stimulator of growth and motility of smooth muscle cells (SMCs) and fibroblasts. Abnormalities of PDGF/PDGF receptor (PDGFR) are thought to contribute to vascular diseases and malignancy. We previously showed that natural carotenoid lycopene can directly bind to PDGF-BB and affect its related functions in vascular SMCs. In this study we examined lycopene effect on PDGF-AA/-AB-induced signaling and migration in SMCs and fibroblasts. We found that lycopene inhibited PDGF-AA-induced SMC and fibroblast migration in a concentration-dependent manner. Lycopene reduced PDGF-AA signaling, including phosphorylation in PDGFR-alpha and its downstream protein kinases/enzymes. It also inhibited PDGF-AB-induced signaling and cell migration. However, lycopene did not affect PDGF-induced reactive oxygen species production and H2O2-induced PDGFR phosphorylation. The binding analysis revealed that lycopene but not beta-carotene could directly bind to PDGF-AA in vitro and in plasma and this binding competitively inhibited lycopene interaction with PDGF-BB, suggesting that lycopene bound to PDGF-AA/-BB at a homologous/similar region within PDGF. Moreover, the docking and binding analyses predicted that the lycopene-binding region within PDGF was located at loop 2 region. Taken together, we provide here evidence that lycopene interacts with PDGF-AA/-AB and compromises their intracellular signaling, leading to a marked inhibition on PDGF-AA/-AB-induced migration in both SMCs and fibroblasts. We also predicted its binding region within PDGF and proved its anti-vascular injury effect in vivo. The results, together with our previous findings, suggest lycopene special affinity/effect for PDGF family and its possible application in prevention in vascular diseases and malignancy.

Effects of cyclic strain and growth factors on vascular smooth muscle cell responses

Under physiological and pathological conditions, vascular smooth muscle cells (SMC) are exposed to different biochemical factors and biomechanical forces. Previous studies pertaining to SMC responses have not investigated the effects of both factors on SMCs. Thus, in our research we investigated the combined effects of growth factors like Bfgf (basic fibroblast growth factor), TGF-β (transforming growth factor β) and PDGF (platelet-derived growth factor) along with physiological cyclic strain on SMC responses. Physiological cyclic strain (10% strain) significantly reduced SMC proliferation compared to static controls while addition of growth factors bFGF, TGF-β or PDGF-AB had a positive influence on SMC growth compared to strain alone. Microarray analysis of SMCs exposed to these growth factors and cyclic strain showed that several bioactive genes (vascular endothelial growth factor, epidermal growth factor receptor, etc.) were altered upon exposure. Further work involving biochemical and pathological cyclic strain stimulation will help us better understand the role of cyclic strain and growth factors in vascular functions and development of vascular disorders.

mRNA differential display identification of vascular smooth muscle early response genes regulated by PDGF

The modulation of vascular smooth muscle cells (VSMCs) from the quiescent phenotype to the proliferative and migratory phenotype is a critical event in the pathogenesis of atherosclerosis. To-date several growth factors, including platelet-derived growth factor, PDGF, have been shown to induce VSMC proliferation and migration. To further understand the mechanism of PDGF-induced VSMC activation, quiescent human coronary artery SMC were treated with PDGF, and the genes that displayed transcriptional changes within 3 and 8 h were identified using differential display RT-PCR, real-time PCR, nucleotide sequencing and bioinformatics. Eleven genes that were highly upregulated or down-regulated at 3 and/or 8 h by PDGF, designated growth-factor regulated VSMC genes (GRSG1-11), were analyzed. GRSG5 and GRSG9-1 were identified as cortactin and cytochrome c oxidase subunit II, respectively. The remaining nine GRSGs were novel. GRSG3, 4, 5 and 9-2 showed wide tissue distribution whereas GRSG10-1, 10-2, and 11 were tissue specific. Cortactin was localized by immunohistochemical staining to the neointima and fibrous cap of human coronary artery atherosclerotic plaques. Domain analysis of open reading frames suggest that the novel GRSGs may participate in signaling, metabolic, translational or migrational processes during PDGF-induced VSMC activation.

Enhanced contractile response of the basilar artery to platelet-derived growth factor in subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The level of platelet-derived growth factor (PDGF) in cerebrospinal fluid is elevated in subarachnoid hemorrhage (SAH). Therefore, the contractile effect of PDGF on the basilar artery was examined in SAH.

METHODS

A rabbit double-hemorrhage SAH model was used. In the medial layers of the control basilar artery, PDGF had no effect on contraction up to 1 nmol/L, whereas 3 nmol/L PDGF induced slight contraction. In SAH, PDGF induced an enhanced contraction with an increase in [Ca(2+)](i) at 1 nmol/L and higher concentrations. The levels of [Ca(2+)](i) and tension induced by 1 nmol/L PDGF in SAH were 17% and 20%, respectively, of those obtained with 118 mmol/L K(+) depolarization. The PDGF-induced elevation of [Ca(2+)](i) and contraction seen in SAH were abolished in the absence of extracellular Ca(2+). In alpha-toxin-permeabilized strips of SAH animals, PDGF induced no further development of tension during contraction induced by 300 nmol/L Ca(2+), suggesting no direct effect on myofilament Ca(2+) sensitivity. Genistein at 10 micromol/L completely inhibited the tension induced by 1 nmol/L PDGF. The level of myosin light-chain phosphorylation was significantly increased by 1 nmol/L PDGF.

CONCLUSIONS

These results show that the contractile response to PDGF of the basilar artery was enhanced in SAH. The PDGF-induced contraction depended mostly on tyrosine phosphorylation and Ca(2+)-dependent myosin light-chain phosphorylation. The enhancement of the responsiveness to PDGF may therefore contribute to the development of cerebral vasospasm after SAH.

Litebamine, a phenanthrene alkaloid from the wood of Litsea cubeba, inhibits rat smooth muscle cell adhesion and migration on collagen

Smooth muscle cells (SMCs) play an important role in the development of atherosclerosis and restenosis after angioplasty and coronary bypass grafting. The pathogenesis of these vascular diseases includes the abnormal production of extracellular matrix (ECM) proteins by SMCs and their interactions with this newly synthesized and preexisting ECM. Litebamine, a natural phenanthrene alkaloid from the wood of Litsea cubeba, has been shown to inhibit platelet aggregation and thromboxane B(2) formation, suggesting its antithrombotic activity. In the present study we examined litebamine effects on vascular SMC adhesion and migration. Our results indicated that litebamine inhibited rat aortic SMCs (RASMCs) and A10 thoracic SMCs adhesion to collagen but not to other matrix proteins, suggesting its specificity on collagen. This inhibition was possibly resulted from that litebamine attenuated immobilized collagen-induced focal adhesion kinase (FAK) phosphorylation and actin cytoskeleton reorganization in RASMCs, as determined by Western blotting and immunofluorescence microscopy. In a functional study, litebamine also inhibited platelet-derived growth factor (PDGF)-induced RASMC migration but did not affect PDGF-induced matrix metalloproteinases (MMPs) secretion. Strikingly, among the tested kinases involved in PDGF-induced migration, only PDGF-induced phosphatidylinositol-3 kinase (PI-3K) activation was inhibited by litebamine. Taken together, we demonstrated here that litebamine can functionally inhibit vascular SMC adhesion and migration and elucidated its possible mechanisms of action. As SMC adhesion and migration are critical events in disease-related vascular remodeling, this compound may have beneficial effects in preventing cardiovascular diseases.

Glucose lowers the threshold for human aortic vascular smooth muscle cell migration: inhibition by protein phosphatase-2A

AIMS/HYPOTHESIS

Atherosclerosis, which occurs prematurely in individuals with diabetes, incorporates vascular smooth muscle cell (VSMC) chemotaxis. Glucose, through protein kinase C-beta(II) signalling, increases chemotaxis to low concentrations of platelet-derived growth factor (PDGF)-BB. In VSMC, a biphasic response in PDGF-beta receptor (PDGF-betaR) level occurs as PDGF-BB concentrations increase. The purpose of this study was to determine whether increased concentrations of PDGF-BB and raised glucose level had a modulatory effect on the mitogen-activated protein kinase/extracellular-regulated protein kinase pathway, control of PDGF-betaR level and chemotaxis.

METHODS

Cultured aortic VSMC, exposed to normal glucose (NG) (5 mmol/l) or high glucose (HG) (25 mmol/l) in the presence of PDGF-BB, were assessed for migration (chemotaxis chamber) or else extracted and immunoblotted.

RESULTS

At concentrations of PDGF-BB <540 pmol/l, HG caused an increase in the level of PDGF-betaR in VSMC (immunoblotting) versus NG, an effect that was abrogated by inhibition of aldose reductase or protein kinase C-beta(II). At higher concentrations of PDGF-BB (>540 pmol/l) in HG, receptor level was reduced but in the presence of aldose reductase or protein kinase C-beta(II) inhibitors the receptor levels increased. It is known that phosphatases may be activated at high concentrations of growth factors. At high concentrations of PDGF-BB, the protein phosphatase (PP)2A inhibitor, endothall, caused an increase in PDGF-betaR levels and a loss of biphasicity in receptor levels in HG. At higher concentrations of PDGF-BB in HG, the chemoattractant effect of PDGF-BB was lost (chemotaxis chamber). Under these conditions inhibition of PP2A was associated with a restoration of chemotaxis to high concentrations of PDGF-BB.

CONCLUSION/INTERPRETATION

The biphasic response in PDGF-betaR level and in chemotaxis to PDGF-BB in HG is due to PP2A activation.

Lycopene inhibits PDGF-BB-induced signaling and migration in human dermal fibroblasts through interaction with PDGF-BB

In melanoma development and progression, platelet-derived growth factor (PDGF) has been suggested to modulate the microenvironment, especially stromal fibroblasts, to the benefit of melanoma growth, invasion, and metastasis. Lycopene, a natural carotenoid that is abundant in tomato, has been shown to inhibit proliferation of several types of cancer cells. However, little attention has been paid to skin fibroblasts and melanoma cells. In the present study, we determined the effects of lycopene on stromal fibroblasts and their interactions with melanoma cells. We found that lycopene inhibited PDGF-BB-induced human Hs68 skin fibroblast migration on gelatin and collagen. Further analysis showed that lycopene inhibited PDGF-BB-induced signaling in human Hs68 and primary cultured skin fibroblasts. PDGF-BB-induced phosphorylation of PDGF receptor beta (PDGFR-beta), extracellular signal-regulated kinase 1/2 (ERK1/2), p38, and c-Jun N-terminal kinase (JNK) was attenuated by lycopene in a concentration-dependent manner, whereas the total expression of each protein was not affected. Interestingly, dot binding assay revealed that lycopene could directly bind to human PDGF-BB in PBS and human plasma, indicating that lycopene can bind to PDGF-BB in both in vitro and in vivo conditions. In functional studies, lycopene inhibited melanoma-induced fibroblast migration in a noncontact coculture system and attenuated signaling in fibroblasts simulated by melanoma-derived conditioned medium. Our results provide the first evidence showing that lycopene is an effective inhibitor of migration of stromal fibroblasts and this effect may contribute to its antitumor activity.

In vitro inhibition of proliferation of vascular smooth muscle cells by serum of rats treated with Dahuang Zhechong pill

Dahuang Zhechong pill (DHZCP) is a famous and classical Chinese herbal prescription, which is clinically used to treat hepatic, gynecological and cardiovascular diseases in China. The aim of this study was to observe the effects of the serum of rats treated with DHZCP on the proliferation of cultured rat vascular smooth muscle cells (VSMCs) stimulated by platelet-derived growth factor (PDGF), oxidized low density lipoprotein (ox-LDL) and hyperlipidemic serum (HLS), and on DNA, protein and collagen syntheses of VSMCs induced by PDGF in vitro. VSMCs proliferation was assayed by measuring the cell viability with MTT method, and syntheses of DNA, protein and collagen were evaluated by detecting [(3)H]-thymidine, [(3)H]-leucine and [(3)H]-proline incorporations, respectively. The results showed that PDGF, ox-LDL and HLS stimulated the proliferation of rat VSMCs in vitro. The serum of rats treated with DHZCP significantly inhibited the proliferation of rat VSMCs induced by the above stimulants and the incorporations of [(3)H]-thymidine, [(3)H]-leucine and [(3)H]-proline into rat VSMCs induced by PDGF in comparison with the model control group (P<0.01). The data suggest that DHZCP is able to obviously inhibit VSMCs proliferation via interfering with syntheses of DNA and protein, and to decrease production of extracellular matrix by VSMCs through antagonizing collagen synthesis.

6A3-5/Osa2 is an early activated gene implicated in the control of vascular smooth muscle cell functions

Vascular smooth muscle cells (VSMC) growth plays a key role in the pathophysiology of vascular diseases. However, the molecular mechanisms controlling gene transcription in VSMC remain poorly understood. We previously identified, by differential display, a new gene (6A3-5) overexpressed in proliferating rat VSMC. In this study, we have cloned the full-length cDNA by screening a rat foetal brain cDNA library and investigated its functions. The 6A3-5 protein shows 4 putative conserved functional motifs: a DNA binding domain called ARID (AT-rich interaction domain), two recently described motifs (Osa Homology Domain), and a nuclear localization signal. The deduced protein sequence was observed to be 85% identical to the recently described human Osa2 gene. Immunolabelling, using an anti-6A3-5/Osa2 monoclonal antibody, showed a nuclear localization of the 6A3-5/Osa2 protein. In addition, PDGF upregulated 6A3-5/Osa2 expression at both the transcript and protein levels in a dose and time-dependent fashion. The pattern of upregulation by PDGF was reminiscent of the early responsive gene c-fos. The PDGF-induced upregulation of 6A3-5/Osa2 and proliferation of VSMC were significantly inhibited in a dose and sequence-dependent fashion by an antisense, but not by sense, scrambled or mismatched oligonucleotides directed against 6A3-5/Osa2. In VSMC of aortas derived from hypertensive (LH) rats, 6A3-5/Osa2 is overexpressed as compared to that in normotensive (LL) rats. The 6A3-5/Osa2-gene expression is downregulated by an ACE inhibitor and upregulated by exogenous AngiotensinII in LH rats. In summary, these results indicate that 6A3-5/Osa2 is an early activated gene that belongs to a new family of proteins involved in the control of VSMC growth.

Lycopene binds PDGF-BB and inhibits PDGF-BB-induced intracellular signaling transduction pathway in rat smooth muscle cells

Cardiovascular diseases (CVDs) result from the sub-endothelial accumulation of inflammatory cells and smooth muscle cells (SMCs). Lycopene, a natural compound from tomato, has been suggested to play a role in CVD prevention. However, its action mechanism is still largely unknown. In this study, we examined the effect of lycopene on SMCs. We found that preincubation of PDGF-BB with lycopene resulted in a marked inhibition on PDGF-BB-induced PDGF receptor-beta (PDGFR-beta), PLCgamma, and ERK1/2 phosphorylation in rat A10 SMCs and primary cultured aortic SMCs. In striking contrast, lycopene did not influence EGF-induced ERK1/2 phosphorylation. Surprisingly, further analysis indicates that lycopene could directly bind PDGF-BB and inhibit PDGF-BB-SMC interaction, as determined by dot binding assay and Western blotting. In functional studies, lycopene inhibited PDGF-BB-induced SMC proliferation and migration toward gelatin and collagen at concentrations ranging from 2 to 10 microM. On the contrary, lycopene did not inhibit bFGF- and VEGF-induced endothelial cell migration. Gelatin zymography demonstrated that lycopene's effect on SMC migration was not due to the inhibition of matrix metalloproteinases (MMPs). Taken together, our results provide the first evidence showing that lycopene inhibits PDGF-BB-induced signaling, proliferation and migration in rat A10 and aortic SMCs. One of the action mechanisms is that lycopene is capable of binding PDGF-BB and inhibiting its interaction with SMC, which is quite different from those previously developed PDGFR-beta antagonists. The results presented here may help us to better understand the beneficial effects of lycopene in CVD prevention.