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

Potential Benefits of Lycopene Consumption: Rationale for Using It as an Adjuvant Treatment for Malaria Patients and in Several Diseases

Malaria is a disease that affects thousands of people around the world every year. Its pathogenesis is associated with the production of reactive oxygen and nitrogen species (RONS) and lower levels of micronutrients and antioxidants. Patients under drug treatment have high levels of oxidative stress biomarkers in the body tissues, which limits the use of these drugs. Therefore, several studies have suggested that RONS inhibition may represent an adjuvant therapeutic strategy in the treatment of these patients by increasing the antioxidant capacity of the host. In this sense, supplementation with antioxidant compounds such as zinc, selenium, and vitamins A, C, and E has been suggested as part of the treatment. Among dietary antioxidants, lycopene is the most powerful antioxidant among the main carotenoids. This review aimed to describe the main mechanisms inducing oxidative stress during malaria, highlighting the production of RONS as a defense mechanism against the infection induced by the ischemia-reperfusion syndrome, the metabolism of the parasite, and the metabolism of antimalarial drugs. Furthermore, the effects of lycopene on several diseases in which oxidative stress is implicated as a cause are outlined, providing information about its mechanism of action, and providing an evidence-based justification for its supplementation in malaria.

Lycopene: A Natural Arsenal in the War against Oxidative Stress and Cardiovascular Diseases

Lycopene is a bioactive red pigment found in plants, especially in red fruits and vegetables, including tomato, pink guava, papaya, pink grapefruit, and watermelon. Several research reports have advocated its positive impact on human health and physiology. For humans, lycopene is an essential substance obtained from dietary sources to fulfil the body requirements. The production of reactive oxygen species (ROS) causing oxidative stress and downstream complications include one of the major health concerns worldwide. In recent years, oxidative stress and its counter strategies have attracted biomedical research in order to manage the emerging health issues. Lycopene has been reported to directly interact with ROS, which can help to prevent chronic diseases, including diabetes and neurodegenerative and cardiovascular diseases. In this context, the present review article was written to provide an accumulative account of protective and ameliorative effects of lycopene on coronary artery disease (CAD) and hypertension, which are the leading causes of death worldwide. Lycopene is a potent antioxidant that fights ROS and, subsequently, complications. It reduces blood pressure via inhibiting the angiotensin-converting enzyme and regulating nitrous oxide bioavailability. It plays an important role in lowering of LDL (low-density lipoproteins) and improving HDL (high-density lipoproteins) levels to minimize atherosclerosis, which protects the onset of coronary artery disease and hypertension. Various studies have advocated that lycopene exhibited a combating competence in the treatment of these diseases. Owing to all the antioxidant, anti-diabetic, and anti-hypertensive properties, lycopene provides a potential nutraceutical with a protective and curing ability against coronary artery disease and hypertension.

P38 MAPK and Nrf2 Activation Mediated Naked Gold Nanoparticle Induced Heme Oxygenase-1 Expression in Rat Aortic Vascular Smooth Muscle Cells

BACKGROUND AND AIMS

Heme oxygenase 1 (HO-1) is mainly regulated by the redox-sensitive transcription factor, namely nuclear factor erythroid 2-related factor 2 (Nrf2). We previously found a physically-made gold nanoparticle (GNP) can affect migration, adhesion, and proliferation of rat aortic vascular smooth muscle cells (VSMCs). This study was sought to investigate whether the GNP can affect HO-1 expression level in VSMCs.

METHODS

Cellular fractionation, Western blotting, and immunofluorescence microscopy were used to determine Nrf2 translocation and phosphorylation. SiRNA interference was used to examine role of Nrf2 in GNP-induced HO-1 expression.

RESULTS

The GNP concentration- and time-dependently enhanced HO-1 protein and mRNA expression; however, the mRNA induction was declined after 16 h treatment. The GNP treatment caused Nrf2 expression level and phosphorylation. In addition, it induced cytosolic Nrf2 translocation into nucleus. The HO-1 induction was inhibited by a ROS scavenger N-acetylcysteine (NAC), thiol-containing antioxidants (glutathione [GSH] and dithiothreitol [DTT]), JNK and p38 MAPK inhibitors, and nuclear transport inhibitor leptomycin. Meanwhile, the GNP-induced Nrf2 translocation (activation) was also reduced by NAC, JNK and p38 MAPK inhibitors, and nuclear transport inhibitor. Intriguingly, the GNP only enhanced activation of p38 MAPK but not JNK1/2. Finally, introduction of Nrf2 siRNA to cells to knockdown Nrf2 expression significantly inhibited GNP-induced HO-1 protein expression.

CONCLUSIONS

This study elucidates the action mechanism that the naked physically-made GNP can enhance HO-1 expression in rat aortic VSMCs by inducing Nrf2 expression and phosphorylation and translocation into nucleus. The Nrf2 activation is mediated through a redox-related reaction and p38 MAPK activation.

Naked physically synthesized gold nanoparticles affect migration, mitochondrial activity, and proliferation of vascular smooth muscle cells

Introduction

Vascular smooth muscle cells (VSMCs) play an important role in the development and progression of atherosclerosis and vascular injuries in terms of proliferation and migration. Therefore, the aim of this study was to investigate the anti-migratory and proliferative effects of naked gold nanoparticles (AuNPs) on VSMCs.

Materials and methods

One set of physically synthesized AuNPs (pAuNPs) and three sets of chemically synthesized AuNPs (cAuNPs) were tested.

Results and discussion

Among them, the pAuNPs were found to significantly and markedly inhibit platelet-derived growth factor (PDGF)-induced VSMC migration. Transmission electron microscopy revealed that the pAuNPs were ingested and aggregated in the cytoplasm at an early stage of treatment, while the viability of VSMCs was not affected within 24 hours of treatment. The pAuNP treatment enhanced cellular mitochondrial activity but inhibited basal and PDGF-induced VSMC proliferation, as determined by MTT, WST-1, and BrdU cell proliferation assays. Furthermore, the pAuNPs did not interfere with PDGF signaling or matrix metalloproteinase-2 expression/activity. Unlike the cAuNPs, the pAuNPs could markedly reduce VSMC adhesion to collagen, which was supported by the findings that the pAuNPs could inhibit collagen-induced tyrosine protein and focal adhesion kinase (FAK) phosphorylation and actin cytoskeleton reorganization during cell adhesion. The in vitro effects of the pAuNPs were confirmed in the in vivo rat balloon-injured carotid artery model by diminishing the proliferating VSMCs.

Conclusion

Taken together, the present study provides the first evidence that naked pAuNPs can reduce VSMC migration and compromise cell adhesion by affecting FAK and tyrosine-protein activation. The pAuNPs also have an inhibitory effect on PDGF-induced VSMC proliferation and can reduce proliferating/migrating VSMC expression in vivo.

Lycopene and Vascular Health

Lycopene is a lipophilic, unsaturated carotenoid, found in red-colored fruits and vegetables, including tomatoes, watermelon, papaya, red grapefruits, and guava. The present work provides an up to date overview of mechanisms linking lycopene in the human diet and vascular changes, considering epidemiological data, clinical studies, and experimental data. Lycopene may improve vascular function and contributes to the primary and secondary prevention of cardiovascular disorders. The main activity profile of lycopene includes antiatherosclerotic, antioxidant, anti-inflammatory, antihypertensive, antiplatelet, anti-apoptotic, and protective endothelial effects, the ability to improve the metabolic profile, and reduce arterial stiffness. In this context, lycopene has been shown in numerous studies to exert a favorable effect in patients with subclinical atherosclerosis, metabolic syndrome, hypertension, peripheral vascular disease, stroke and several other cardiovascular disorders, although the obtained results are sometimes inconsistent, which warrants further studies focusing on its bioactivity.

Vascular smooth muscle cell proliferation as a therapeutic target. Part 2: Natural products inhibiting proliferation

Many natural products have been so far tested regarding their potency to inhibit vascular smooth muscle cell proliferation, a process involved in atherosclerosis, pulmonary hypertension and restenosis. Compounds studied in vitro and in vivo as VSMC proliferation inhibitors include, for example indirubin-3'-monoxime, resveratrol, hyperoside, plumericin, pelargonidin, zerumbone and apamin. Moreover, taxol and rapamycin, the most prominent compounds applied in drug-eluting stents to counteract restenosis, are natural products. Numerous studies show that natural products have proven to yield effective inhibitors of vascular smooth muscle cell proliferation and ongoing research effort might result in the discovery of further clinically relevant compounds.

A Phenanthrene Derivative, 5,7-Dimethoxy-1,4-Phenanthrenequinone, Inhibits Cell Adhesion Molecule Expression and Migration in Vascular Endothelial and Smooth Muscle Cells

The activation of endothelial cells (ECs) and migration of vascular smooth muscle cells (VSMCs) have played a crucial role in monocyte chemotaxis/adhesion and intima thickening during vascular injury and atherosclerosis, respectively. Several phenanthrenes isolated from plants and natural products have been shown to possess different bioactivities such as anti-platelet aggregation and anti-inflammation. The current study was designated to investigate the effects of a phenanthrene derivative, 5,7-dimethoxy-1,4-phenanthrenequinone (DMPQ), on cell adhesion molecule (CAM) expression in vascular ECs and migration in VSMCs. The DMPQ attenuated monocyte-EC interaction but it did not affect monocyte adhesion to matrix. In parallel, DMPQ reduced tumor necrosis factor-α (TNF-α)-induced intercellular adhesion molecule and vascular CAM expression in ECs. DMPQ compromised TNF-α-induced IκB activation, nuclear factor-kappa B (NF-κB) translocation, and NF-κB-DNA complex formation. Moreover, it affected TNF-α- and hydrogen peroxide (H2O2)-induced reactive oxygen species production and IκB activation. These suggest that DMPQ affects CAM expression by affecting NF-κB signaling. Meanwhile, DMPQ could also inhibit platelet-derived growth factor (PDGF)-induced VSMC migration toward collagen by affecting cellular PDGF signaling, including PDGFRβ, PLCγ, ERK1/2, and Akt phosphorylation. The VSMC adhesion to collagen and collagen-induced focal adhesion kinase activation during cell adhesion were impaired by DMPQ treatment. This study reveals a phenanthrene derivative-DMPQ-with anti-inflammatory and anti-migratory bioactivity toward vascular ECs and SMCs, suggesting its protective effect on vascular injuries.

Cardiovascular benefits of lycopene: fantasy or reality?

Epidemiological evidence indicates that high consumption of tomatoes and tomato-based products reduces the risk of chronic diseases such as CVD and cancer. Such potential benefits are often ascribed to high concentrations of lycopene present in tomato products. Mainly from the results of in vitro studies, potential biological mechanisms by which carotenoids could protect against heart disease and cancer have been suggested. These include cholesterol reduction, inhibition of oxidation processes, modulation of inflammatory markers, enhanced intercellular communication, inhibition of tumourigenesis and induction of apoptosis, metabolism to retinoids and antiangiogenic effects. However, with regard to CVD, results from intervention studies gave mixed results. Over fifty human intervention trials with lycopene supplements or tomato-based products have been conducted to date, the majority being underpowered. Many showed some beneficial effects but mostly on non-established cardiovascular risk markers such as lipid peroxidation, DNA oxidative damage, platelet activation and inflammatory markers. Only a few studies showed improvement in lipid profiles, C reactive protein and blood pressure. However, recent findings indicate that lycopene could exert cardiovascular protection by lowering HDL-associated inflammation, as well as by modulating HDL functionality towards an antiatherogenic phenotype. Furthermore, in vitro studies indicate that lycopene could modulate T lymphocyte activity, which would also inhibit atherogenic processes and confer cardiovascular protection. These findings also suggest that HDL functionality deserves further consideration as a potential early marker for CVD risk, modifiable by dietary factors such as lycopene.

MicroRNA-let-7f-1 is induced by lycopene and inhibits cell proliferation and triggers apoptosis in prostate cancer

Previous studies have suggested that lycopene has cytotoxic effects in a variety of types of human cancer. An improved understanding of the mechanisms underlying the anticancer effects of lycopene may provide novel therapeutic targets for cancer treatment. PC3 cells were treated with different concentrations of lycopene for 24 and 48 h, the level of protein kinase B (AKT2) was detected by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blotting. Additionally, the expression levels of microRNA (miR)‑let‑7f‑1 were measured using RT‑qPCR. miR‑let‑7f‑1 function was analyzed using cell proliferation and apoptosis assays in gain‑ and loss‑of‑function experiments. It was observed that lycopene downregulated the expression of AKT2 and upregulated the expression of miR‑let‑7f‑1 in PC3 cells. Re‑introduction of miR‑let‑7f‑1 into PC3 cells was able to inhibit cell proliferation and induce apoptosis. Further investigation indicated that miR‑let‑7f‑1 targeted AKT2 in PC3 cells and upregulation of AKT2 could attenuate the effects induced by miR‑let‑7f‑1. The results of the current study indicate that miR‑let‑7f‑1 is involved in the anticancer effects of lycopene and serves an important role in the inhibition of prostate cancer progression through the downregulation of AKT2.

Effects of all-trans retinoic acid, retinol, and β-carotene on murine macrophage activity

Previous studies have demonstrated that vitamin A and carotenoids regulate immune function in lymphocytes and splenocytes, and that the carotenoid lutein regulates matrix metalloproteinase-9 (MMP-9) production in macrophages. In this study, we investigated the effects of all-trans retinoic acid (atRA, a bioactive vitamin A metabolite), retinol (vitamin A), and β-carotene (vitamin A precursor) on the activity of murine RAW264.7 and peritoneal macrophages. Our results indicated that atRA and retinol could induce GM-CSF and IL-16 expression, whereas all these tested substances enhanced MMP-9 production. Interestingly, the expression of GM-CSF, IL-16, and MMP-9 was distinctly regulated by these three substances. AtRA and retinol affected GM-CSF and IL-16 expression mainly through RA receptor β (RARβ). However, atRA induced MMP-9 production was via RARα activation and retinol and β-carotene caused MMP-9 production via RARα and β activation. These were supported by the observations that the RARα and β agonists/antagonists differentially affected MMP-9 production and that atRA and β-carotene enhanced RARE-mediated and MMP-9 promoter luciferase activity. In parallel, while the MMP-9 induction by atRA was not affected by the MAPKs inhibitors, its induction by retinol and β-carotene was repressed by the inhibitor targeting ERK1/2. Finally, we show that all the tested substances could functionally enhance macrophage phagocytosis. Taken together, we provide evidence here for the first time that atRA, retinol, and β-carotene differentially regulate GM-CSF, IL-16, and MMP-9 production in macrophages, explaining at least in part why these vitamin A-related substances are beneficial for immunity.

Use of dietary phytochemicals to target inflammation, fibrosis, proliferation, and angiogenesis in uterine tissues: promising options for prevention and treatment of uterine fibroids?

Uterine leiomyomas (fibroids, myomas) are the most common benign tumors of female reproductive tract. They are highly prevalent, with 70-80% of women burdened by the end of their reproductive years. Fibroids are a leading cause of pelvic pain, abnormal vaginal bleeding, pressure on the bladder, miscarriage, and infertility. They are the leading indication for hysterectomy, and costs exceed 6 billion dollars annually in the United States. Unfortunately, no long-term medical treatments are available. Dysregulation of inflammatory processes are thought to be involved in the initiation of leiomyoma and extracellular matrix deposition, cell proliferation, and angiogenesis are the key cellular events implicated in leiomyoma growth. In modern pharmaceutical industries, dietary phytochemicals are used as source of new potential drugs for many kinds of tumors. Dietary phytochemicals may exert therapeutic effects by interfering with key cellular events of the tumorigenesis process. At present, a negligible number of phytochemicals have been tested as therapeutic agents against fibroids. In this context, our aim was to introduce some of the potential dietary phytochemicals that have shown anti-inflammatory, antiproliferative, antifibrotic, and antiangiogenic activities in different biological systems. This review could be useful to stimulate the evaluation of these phytochemicals as possible therapies for uterine fibroids.

Protective effect of lycopene on cardiac function and myocardial fibrosis after acute myocardial infarction in rats via the modulation of p38 and MMP-9

Extracellular matrix (ECM) plays an important role in maintaining the left ventricular geometry and ventricular function, and the inhibition of ECM remodeling has therapeutic benefits that could alleviate the progression of ventricular remodeling. Recent studies have indicated that lycopene has cardioprotective effects. In this study, a rat myocardial infarction (MI) model was established by left anterior descending coronary artery ligation. After the operation, the rats received lycopene or saline. After 28 days, the rats underwent echocardiography detection and were sacrificed. Myocardial fibrosis was observed by Masson staining. Type I collagen, MMP-9, and MAPK protein expression were detected in the ischemic zone surrounding the MI by western blot. Treatment with lycopene increased the EF from 45.2 ± 3.12 % to 51.1 ± 4.63, and it decreased the LVEDd from 6.52 ± 0.37 mm to 6.18 ± 0.41 mm and the LVESd from 4.29 ± 0.63 to 3.94 ± 0.37 at 28 days post-myocardial infarction. Lycopene attenuated the MI-induced increase in MMP-9 and type I collagen expression, and inhibited p38 activation. Moreover, lycopene decreased the collagen volume fraction in the peri-infarcted zone. The data indicated that lycopene improved the cardiac function and ventricular remodeling by inhibiting p38 activation and MMP-9 expression.

Tomato extract and the carotenoids lycopene and lutein improve endothelial function and attenuate inflammatory NF-κB signaling in endothelial cells

OBJECTIVES

In our previous research the antihypertensive properties of lycopene-containing tomato oleoresin have been revealed. The present study was aimed to assess if oleoresin interferes in the inflammatory signalling in endothelial cells, imitating reduction of inflammatory processes in the vessel wall and in this way to propose the mechanism for the reduction of blood pressure by oleoresin.

METHODS AND RESULTS

A wide number of functional and inflammatory markers were investigated in two cultured endothelial cell models [EA.hy926 and human umbilical vein endothelial cell (HUVEC)], exposed to oleoresin and carotenoids lycopene and lutein. All the carotenoids significantly improved basic endothelial function as measured by increased nitric oxide and decreased endothelin (ET-1) release. They were effective in attenuation of inflammatory nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signalling: decrease of tumour necrosis factor-alpha (TNF-α)-induced leukocytes adhesion, expression of adhesion molecules inter-cellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), and nuclear translocation of NF-κB components as well as some revert of inhibitor of kappa B (IκB) ubiquitination. In addition, the carotenoids were able to inhibit NF-κB activation in transfected endothelial cells. When combined with lutein, oleoresin exerted synergistic effect on preclusion of leukocytes adhesion.

CONCLUSIONS

Prevention of over-expression of adhesion molecules through inhibition of NF-κB signalling may be one of the main mechanisms driving carotenoids to attenuate inflammatory leukocyte adhesion to endothelium. This is the first profound study on the mechanisms involved in the positive action of natural tomato products in endothelial cells.

Multiple molecular and cellular mechanisms of action of lycopene in cancer inhibition

Epidemiological studies suggest that including fruits, vegetables, and whole grains in regular dietary intake might prevent and reverse cellular carcinogenesis, reducing the incidence of primary tumours. Bioactive components present in food can simultaneously modulate more than one carcinogenic process, including cancer metabolism, hormonal balance, transcriptional activity, cell-cycle control, apoptosis, inflammation, angiogenesis and metastasis. Some studies have shown an inverse correlation between a diet rich in fruits, vegetables, and carotenoids and a low incidence of different types of cancer. Lycopene, the predominant carotenoid found in tomatoes, exhibits a high antioxidant capacity and has been shown to prevent cancer, as evidenced by clinical trials and studies in cell culture and animal models. In vitro studies have shown that lycopene treatment can selectively arrest cell growth and induce apoptosis in cancer cells without affecting normal cells. In vivo studies have revealed that lycopene treatment inhibits tumour growth in the liver, lung, prostate, breast, and colon. Clinical studies have shown that lycopene protects against prostate cancer. One of the main challenges in cancer prevention is the integration of new molecular findings into clinical practice. Thus, the identification of molecular biomarkers associated with lycopene levels is essential for improving our understanding of the mechanisms underlying its antineoplastic activity.

The carotenoid lutein enhances matrix metalloproteinase-9 production and phagocytosis through intracellular ROS generation and ERK1/2, p38 MAPK, and RARβ activation in murine macrophages

Carotenoid lutein causes MMP-9 release that participates in macrophage phagocytosis.

Early studies have demonstrated the ability of dietary carotenoids to enhance immune response, but the mechanism underlying their influence on macrophage activity remains unclear. Here, we investigated the effects of carotenoids on macrophage activity. Carotenoids, including lutein and lycopene, enhanced MMP-9 activity in RAW264.7 macrophages. Lutein was chosen as a representative and analyzed further in this study. It increased the synthesis, activity, and release of MMP-9 in murine RAW264.7 and primary-cultured peritoneal macrophages. MMP-9 induction by lutein was through the transcriptional regulation of mmp-9. It was blunted by the MAPK inhibitors targeting ERK1/2 and p38 MAPK, the reagents that inhibit free radical signaling, and the inhibitors and siRNA targeting RARβ. Moreover, lutein induced Nox activation and intracellular ROS production at an early stage of treatment. This carotenoid also caused ERK1/2 and p38 MAPK activation, RARβ expression, and RAR interaction with its responsive element in the promoter region. These findings suggest the involvement of ROS, MAPKs, and RARβ activation in lutein-driven MMP-9 expression and release. Interestingly, lutein enhanced the phagocytic activity of macrophages, and the secreted MMP-9 appeared to be involved in this process. In summary, we provide evidence here for the first time that the carotenoid lutein induces intracellular ROS generation and MAPK and RARβ activation in macrophages, leading to an increase in MMP-9 release and macrophage phagocytosis. Our results demonstrate that lutein exerts an immunomodulatory effect on macrophages.

Lycopene protects against hypoxia/reoxygenation-induced apoptosis by preventing mitochondrial dysfunction in primary neonatal mouse cardiomyocytes

BACKGROUND

Hypoxia/reoxygenation(H/R)-induced apoptosis of cardiomyocytes plays an important role in myocardial injury. Lycopene is a potent antioxidant carotenoid that has been shown to have protective properties on cardiovascular system. The aim of the present study is to investigate the potential for lycopene to protect the cardiomyocytes exposed to H/R. Moreover, the effect on mitochondrial function upon lycopene exposure was assessed.

METHODS AND FINDINGS

Primary cardiomyocytes were isolated from neonatal mouse and established an in vitro model of H/R which resembles ischemia/reperfusion in vivo. The pretreatment of cardiomyocytes with 5 µM lycopene significantly reduced the extent of apoptosis detected by TUNEL assays. To further study the mechanism underlying the benefits of lycopene, interactions between lycopene and the process of mitochondria-mediated apoptosis were examined. Lycopene pretreatment of cardiomyocytes suppressed the activation of the mitochondrial permeability transition pore (mPTP) by reducing the intracellular reactive oxygen species (ROS) levels and inhibiting the increase of malondialdehyde (MDA) levels caused by H/R. Moreover, the loss of mitochondrial membrane potential, a decline in cellular ATP levels, a reduction in the amount of cytochrome c translocated to the cytoplasm and caspase-3 activation were observed in lycopene-treated cultures.

CONCLUSION

The present results suggested that lycopene possesses great pharmacological potential in protecting against H/R-induced apoptosis. Importantly, the protective effects of lycopene may be attributed to its roles in improving mitochondrial function in H/R-treated cardiomyocytes.

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.

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.

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.

Activation of c-Jun N-terminal kinase is essential for mitochondrial membrane potential change and apoptosis induced by doxycycline in melanoma cells

BACKGROUND AND PURPOSE

Tetracyclines were recently found to induce tumour cell death, but the early processes involved in this cytotoxic effect remain unclear.

EXPERIMENTAL APPROACH

Viability of human and mouse melanoma cells was determined by MTT assay and flow cytometry. Kinase/protein/caspase activation was measured by Western blotting and mitochondrial membrane potential (DeltaPsi(m)) was analyzed by fluorescence microscopy and flow cytometry.

KEY RESULTS

Human and mouse melanoma cells were treated with doxycycline or minocycline but only doxycycline was cytotoxic. This cell death (apoptosis) in A2058 cells involved activation of caspase-3, -7 and -9 and contributed to inhibition, by doxycycline, of matrix metalloproteinase (MMP) activity and migration of these cells. Doxycycline induced intra-cellular reactive oxygen species (ROS) production, apoptosis signal-regulated kinase 1 (ASK1), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) activation at an early stage of treatment and induced mitochondrial cytochrome c release into cytosol and DeltaPsi(m) change during apoptosis. The JNK inhibitor/small interference RNA inhibited doxycycline-induced JNK activation, DeltaPsi(m) change and apoptosis, but did not affect ASK1 activation, suggesting a role of ASK1 for JNK activation in melanoma cell apoptosis. Two ROS scavengers reduced doxycycline-induced JNK and caspase activation, and apoptosis. Taken together, the results suggest the involvement of a ROS-ASK1-JNK pathway in doxycycline-induced melanoma cell apoptosis.

CONCLUSIONS AND IMPLICATIONS

We have shown a promising cytotoxic effect of doxycycline on melanoma cells, have identified ROS and ASK1 as the possible initiators and have demonstrated that JNK activation is necessary for doxycycline-induced melanoma cell apoptosis.

Lack of effects of tomato products on endothelial function in human subjects: results of a randomised, placebo-controlled cross-over study

Epidemiological studies suggest that consumption of tomato products reduces the risk of CVD via antioxidant, hypocholesterolaemic and anti-inflammatory mechanisms. Although experimental data also describe beneficial effects on endothelial function, clinical data in human subjects are lacking. To test the hypothesis that tomato ingestion ameliorates endothelial function, we randomised healthy non-smoking postmenopausal women to consume a buttered roll with and without tomato purée (70 g) in a cross-over design. Endothelial-dependent flow-mediated dilation (FMD) and endothelial-independent nitro-mediated dilation of the brachial artery were assessed with high-resolution ultrasound (13 MHz linear array transducer). Acute (24 h) and long-term (7 d) effects were examined after daily consumption of the described meal. Nineteen volunteers completed the protocol and provided technically suitable ultrasound measurement data. Plasma lycopene levels increased from 0·30 (sem0·04) (baseline) to 0·42 (sem0·04) and to 0·74 (sem0·06) μmafter 24 h and 7 d, respectively, with tomato purée consumption. These data indicated an effective absorption of the tomato product. However, both acute and long-term tomato purée consumption had no effects on endothelium-dependent or -independent dilation of the brachial artery. In addition, we found no correlation between lycopene plasma levels and FMD. In conclusion, consumption of tomato products associated with a significant increase in plasma lycopene levels had no effects on endothelial function in healthy postmenopausal women.

Lovastatin inhibits gap junctional communication in cultured aortic smooth muscle cells

BACKGROUND

Gap junctions, which serve as intercellular channels that allow the passage of ions and other small molecules between neighboring cells, play an important role in vital functions, including the regulation of cell growth, differentiation, and development. Statins, the 3-hydroxy-3-methylglutaryl-coenzymeA (HMG-CoA) reductase inhibitors, have been shown to inhibit the migration and proliferation of smooth muscle cells (SMCs) leading to an antiproliferative effect. Recent studies have shown that statins can reduce gap junction protein connexin43 (Cx43) expression both in vivo and in vitro. However, little work has been done on the effects of statins on gap junctional intercellular communication (GJIC). We hypothesized in this study that lovastatin inhibits vascular smooth muscle cells (VSMCs) migration through the inhibition of the GJIC.

METHODS

Rat aortic SMCs (RASMCs) were exposed to lovastatin. Vascular smooth muscle cells migration was then assessed with a Transwell migration assay. Gap junctional intercellular communication was determined by using fluorescence recovery after photobleaching (FRAP) analysis, which was performed with a laser-scanning confocal microscope.

RESULTS

The migration of the cultured RASMCs were detected by Transwell system. Cell migration was dose-dependently inhibited with lovastatin. Compared with that in the control (110 ± 26), the number of migrated SMCs was significantly reduced to 72 ± 24 (P < .05), 62 ± 18 (P < .01), and 58 ± 19 (P < .01) at the concentration of 0.4, 2, and 10 umol/L, per field. The rate of fluorescence recovery (R) at 5 minutes after photobleaching was adopted as the functional index of GJIC. The R- value of cells exposed to lovastatin 10 umol/L for 48 hours was 24.38% ± 4.84%, whereas the cells in the control group had an R- value of 36.11% ± 10.53%, demonstrating that the GJIC of RASMCs was significantly inhibited by lovastatin (P < .01). Smaller concentrations of lovastatin 0.08 umol/L did not change gap junction coupling (P > .05).

CONCLUSIONS

These results suggest that lovastatin inhibits migration in a dose-dependent manner by attenuating JIC. Suppression of gap junction function could add another explanation of statin-induced antiproliferative effect.

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.

Sennoside B inhibits PDGF receptor signaling and cell proliferation induced by PDGF-BB in human osteosarcoma cells

AIMS

To address the possibility that sennoside B inhibition of cell proliferation is mediated via interference with platelet-derived growth factor (PDGF) signaling.

MAIN METHODS

Human osteosarcoma MG63 cells were treated with PDGF in the presence or absence of sennoside B. Activation of the PDGF signaling pathway was monitored using western immunoblotting with specific antibodies against the PDGF receptor, phosphotyrosine and components of the downstream signaling cascade. Activation of cell metabolism and proliferation was assessed by chromogenic reduction of MTT.

KEY FINDINGS

Sennoside B was found to inhibit PDGF-BB-induced phosphorylation of the PDGF receptor (PDGFR) in human MG63 osteosarcoma cells. Downstream signaling was also affected; pre-incubation of PDGF-BB with sennoside B inhibited the phosphorylation of pathway components including Ak strain transforming protein (AKT), signal transducer and activator of transcription 5 (STAT-5) and extracellular signal-regulated kinase 1/2 (ERK1/2). Further, we found that sennoside B can bind directly to the extracellular domains of both PDGF-BB and the PDGF-beta receptor (PDGFR-beta). The effect was specific for sennoside B; other similar compounds including aloe-emodin, rhein and the meso isomer (sennoside A) failed to inhibit PDGFR activation or downstream signaling. Sennoside B also inhibited PDGF-BB stimulation of MG63 cell proliferation.

SIGNIFICANCE

These results indicate that sennoside B can inhibit PDGF-stimulated cell proliferation by binding to PDGF-BB and its receptor and by down-regulating the PDGFR-beta signaling pathway. Sennoside B is therefore of potential utility in the treatment of proliferative diseases in which PDGF signaling plays a central role.

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.

Lycopene inhibits TNF-alpha-induced endothelial ICAM-1 expression and monocyte-endothelial adhesion

Inflammatory mediators such as TNF-alpha and interleukin (IL)-1beta, and IL-8, which can enhance binding of low-density lipoprotein (LDL) to endothelium and upregulate expression of leukocyte adhesion molecules on endothelium during atherogenesis. Lycopene, a natural carotenoid from tomato and other sources, has been shown to prevent cardiovascular diseases in epidemiological studies. However, its anti-inflammatory action mechanism remains unclear. In the present study, we studied the effect of lycopene on TNF-alpha-induced signaling in human umbilical endothelial cells (HUVECs). We found that TNF-alpha-induced intercellular adhesion molecule-1 (ICAM-1) expression in HUVECs was inhibited by lycopene, whereas cyclooxygenase-2 (COX-2) and platelet-endothelial cell adhesion molecule (PECAM-1) expression were not affected. A further analysis indicated that lycopene attenuated TNF-alpha-induced IkappaB phosphorylation, NF-kappaB expression, and NF-kappaB p65 translocation from cytosol to nucleus. In line with this, TNF-alpha-induced NF-kappaB-DNA but not AP1-DNA complexes formation was inhibited by lycopene, as determined by the electrophoretic mobility shift assay (EMSA). On the other hand, lycopene did not affect TNF-alpha-induced p38 and extracellular matrix-regulated kinase1/2 (ERK1/2) phosphorylation and interferon-gamma (IFN-gamma)-induced signaling, suggesting that lycopene primarily affects TNF-alpha-induced NF-kappaB signaling pathway. In a functional study, lycopene dose-dependently attenuated monocyte adhesion to endothelial monolayer but not that adhesion to extracellular matrix. Taken together, we provided here the first evidence showing that lycopene is able to inhibit TNF-alpha-induced NF-kappaB activation, ICAM-1 expression, and monocyte-endothelial interaction, suggesting an anti-inflammatory role of lycopene and possibly explaining in part why lycopene can prevent cardiovascular diseases.

Inhibitory effect of lycopene on PDGF-BB-induced signalling and migration in human dermal fibroblasts: a possible target for cancer

Tumours are complex tissues composed of both matrix proteins and stromal cells such as fibroblasts and inflammatory cells. Tumour progression is often the result of dynamic interactions between the tumour cells and their surroundings. Lycopene, a natural carotenoid that is abundant in tomato, has been shown to inhibit proliferation of several types of cancer cells through arrest of tumour cell-cycle progression, IGF-1 (insulin-like growth factor 1) signalling transduction, induction of apoptosis etc. However, in our recent study, we found that lycopene inhibited PDGF-BB (platelet-derived growth factor-BB)-induced signalling and cell migration in human cultured skin fibroblasts through a novel mechanism of action, i.e. direct binding to PDGF-BB. Trapping of PDGF by lycopene also compromised melanoma-induced fibroblast migration and attenuated signalling transduction in fibroblasts simulated by melanoma-derived conditioned medium, suggesting that lycopene may interfere with tumour-stroma interactions. The trapping activity of lycopene on PDGF suggests that it may act as an inhibitor on stromal cells, tumour cells and their interactions, which may contribute to its anti-tumour activity.

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.