Tissue factor induces human coronary artery smooth muscle cell motility through Wnt-signalling

Caffeine prevents restenosis and inhibits vascular smooth muscle cell proliferation through the induction of autophagy

Caffeine is among the most highly consumed substances worldwide, and it has been associated with decreased cardiovascular risk. Although caffeine has been shown to inhibit the proliferation of vascular smooth muscle cells (VSMCs), the mechanism underlying this effect is unknown. Here, we demonstrated that caffeine decreased VSMC proliferation and induced macroautophagy/autophagy in an in vivo vascular injury model of restenosis. Furthermore, we studied the effects of caffeine in primary human and mouse aortic VSMCs and immortalized mouse aortic VSMCs. Caffeine decreased cell proliferation, and induced autophagy flux via inhibition of MTOR signaling in these cells. Genetic deletion of the key autophagy gene Atg5, and the Sqstm1/p62 gene encoding a receptor protein, showed that the anti-proliferative effect by caffeine was dependent upon autophagy. Interestingly, caffeine also decreased WNT-signaling and the expression of two WNT target genes, Axin2 and Ccnd1 (cyclin D1). This effect was mediated by autophagic degradation of a key member of the WNT signaling cascade, DVL2, by caffeine to decrease WNT signaling and cell proliferation. SQSTM1/p62, MAP1LC3B-II and DVL2 were also shown to interact with each other, and the overexpression of DVL2 counteracted the inhibition of cell proliferation by caffeine. Taken together, our in vivo and in vitro findings demonstrated that caffeine reduced VSMC proliferation by inhibiting WNT signaling via stimulation of autophagy, thus reducing the vascular restenosis. Our findings suggest that caffeine and other autophagy-inducing drugs may represent novel cardiovascular therapeutic tools to protect against restenosis after angioplasty and/or stent placement.

Tissue factor: a neglected role in cancer biology

Tissue factor (TF), an initiator of extrinsic coagulation pathway, is positively correlated with venous thromboembolism (VTE) of tumor patients. Beyond thrombosis, TF plays a vital role in tumor progression. TF is highly expressed in cancer tissues and circulating tumor cell (CTC), and activates factor VIIa (FVIIa), which increases tumor cells proliferation, angiogenesis, epithelial-mesenchymal transition (EMT) and cancer stem cells(CSCs) activity. Furthermore, TF and TF-positive microvesicles (TF⁺MVs) activate the coagulation system to promote the clots formation with non-tumor cell components (e.g., platelets, leukocytes, fibrin), which makes tumor cells adhere to clots to form CTC clusters. Then, tumor cells utilize clots to cause its reducing fluid shear stress (FSS), anoikis resistance, immune escape, adhesion, extravasation and colonization. Herein, we review in detail that how TF signaling promotes tumor metastasis, and how TF-targeted therapeutic strategies are being in the preclinical and clinical trials.

Aralia armata (Wall.) Seem Improves Intimal Hyperplasia after Vascular Injury by Downregulating the Wnt3α/Dvl-1/β-Catenin Pathway

The aim of the study is to examine the mechanism of Aralia armata (Wall.) Seem (AAS) in improving intimal hyperplasia after vascular injury in rats. Rats with femoral artery injury were randomly divided into three groups: the model group, AAS low-dose group (40 mg/kg), and AAS high-dose group (80 mg/kg). The sham operation group was used as a control group. HE staining was used to observe the changes in femoral artery vessels. Immunohistochemistry was adopted to detect α-SMA, PCNA, GSK-3β, and β-catenin proteins in femoral artery tissue. The CCK-8 test and wound healing assay were employed to analyze the effect of AAS on proliferation and migration of vascular smooth muscle cells (VSMCs) cultured in vitro. Western blotting (WB) and polymerase chain reaction (PCR) assays were used to evaluate the molecular mechanism. AAS reduced the stenosis of blood vessels and the protein expressions of α-SMA, PCNA, GSK-3β, and β-catenin compared to the model group. In addition, AAS (0-15 μg/mL) effectively inhibited the proliferation and migration of VSMCs. Moreover, the results of WB and PCR showed that AAS could inhibit the activation of β-catenin induced by 15% FBS and significantly decrease the expression levels of Wnt3α, Dvl-1, GSK-3β, β-catenin, and cyclin D1 in the upstream and downstream of the pathway. AAS could effectively inhibit the proliferation and migration of neointima after vascular injury in rats by regulating the Wnt/β-catenin signaling pathway.

Improved in vivo detection of atherosclerotic plaques with a tissue factor-targeting magnetic nanoprobe

Rupture of atherosclerotic plaques causes acute cardiovascular and cerebrovascular pathology. Tissue factor (TF) is a key factor that affects the development of atherosclerotic plaques and the formation of thrombus and thus constitutes a potential target for the detection of atherosclerotic plaques. In this study, the conjugation of the fusion protein 'enhanced green fluorescent protein with the first epidermal growth factor domain' (EGFP-EGF1) and superparamagnetic iron oxide nanoparticles (EGFP-EGF1-SPIONs) was explored for molecular imaging of TF-positive atherosclerotic plaques. EGFP-EGF1-SPIONs showed improved accuracy, superior contrast effects, and better cytocompatibility compared with common contrast agents in the detection of atherosclerotic plaques of apolipoprotein E knockout (ApoE^-/-) mice using magnetic resonance imaging. In conclusion, EGFP-EGF1-SPION is a promising TF-targeting nanoprobe to precisely and specifically detect atherosclerotic plaques, which may improve molecular imaging diagnosis of cardiovascular and cerebrovascular events for the comprehensive evaluation of atherosclerosis. STATEMENT OF SIGNIFICANCE: Traditional methods can only display the status of atherosclerosis, but not forecast the progress of lesions efficiently. It remains challenging to evaluate the plaques specifically and sensitively. In this study, we constructed a tissue factor-targeted magnetic nanoprobe to specifically detect plaques by magnetic resonance imaging in vivo, which will improve the diagnostic technology for atherosclerotic plaques and offer molecular level guidance to treat atherosclerosis. Furthermore, this strategy has critical clinical significance on prevention, diagnosis and therapeutic evaluation of cardio-cerebral vascular events.

Protein disulphide-isomerase A2 regulated intracellular tissue factor mobilisation in migrating human vascular smooth muscle cells

Protein-disulphide isomerase family (PDI) are an ER-stress protein that controls TF-procoagulant activity but its role in HVSMC migration and coronary artery disease remains to be elucidated. We aimed to investigate whether in human coronary smooth muscle cells (HVSMC) the ER-stress protein-disulphide isomerase family A member 2 (PDIA2) regulates tissue factor (TF) polarisation during migration and atherosclerotic remodeling. PDIA2 and TF were analysed by confocal microscopy, silenced by small interfering RNAs (siRNA) and their function analysed by transwell and migration assays in vitro and in vivo. PDIA2and TF co-localise in the front edge of motile HVSMC. Silencing PDIA2, as well as silencing TF, reduces migration. PDIA2 silenced cells show increased TF-rich microparticle shedding. In vivo cell-loaded plug implants in nude mice of PDIA2 silenced HVSMC together with microvascular endothelial cells showed a significant impairment in mature microvessel formation. PDIA2 and TF are found in remodelled atherosclerotic plaques but not in healthy coronaries. In conclusion, we demonstrate that TF is chaperoned by PDIA2 to the HVSMC membrane and to the cell migratory front. Absence of PDIA2 impairs TF intracellular trafficking to its membrane docking favoring its uncontrolled release in microparticles. TF-regulated HVSMC migration and microvessel formation is under the control of the ER-protein PDIA2.

Oligoubiquitination of tissue factor on Lys255 promotes Ser253-dephosphorylation and terminates TF release

Restriction of tissue factor (TF) activity at the cell surface and TF release are critical for prevention of excessive coagulation. This study examined the regulation of TF dephosphorylation and its release through ubiquitination. A plasmid containing the sequence to express the tandem protein TF-tGFP was mutated to include an arginine-substitution at Lys255 within TF. MDA-MB-231 cell line, and HCAEC endothelial cells were transfected and subsequently activated with PAR2-agonist peptide. The wild-type and mutant TF-tGFP were immunoprecipitated from the cell lysates and the ubiquitination and phosphorylation state of TF examined. Analysis of the proteins showed that arginine-substitution of Lys255 within TF prevented its ubiquitination while the wild-type TF-tGFP was oligoubiquitinated. The TF-associated oligoubiquitin chain was estimated to contain up to 4 ubiquitin units, with the linkage formed between Lys63 of one ubiquitin unit, and the C-terminus of the next unit. The Lys255→Arg substitution of TF-tGFP prolonged the phosphorylation of Ser253 within TF, compared to the wild-type TF-tGFP, lengthened the presence of TF-tGFP at the cell surface and extended the duration of TF-tGFP release from cells following PAR2 activation. A biotinylated 19-mer peptide corresponding to the C-terminus of TF (TFc) was used as substrate to show that the ubiquitination of TF was mediated by the Ube2D family of E2-enzymes and involved Mdm2. Moreover, double-phosphorylation of TFc was prerequisite for ubiquitination, with subsequent dephosphorylation of Ser253 by phosphatase PP2A. In conclusion, oligoubiquitination of Lys255 within TF permits PP2A to bind and dephosphorylate Ser253 and occurs to terminate TF release and contain its activity.

Wnt2 and WISP-1/CCN4 Induce Intimal Thickening via Promotion of Smooth Muscle Cell Migration

OBJECTIVE

Increased vascular smooth muscle cell (VSMC) migration leads to intimal thickening which acts as a soil for atherosclersosis, as well as causing coronary artery restenosis after stenting and vein graft failure. Investigating factors involved in VSMC migration may enable us to reduce intimal thickening and improve patient outcomes. In this study, we determined whether Wnt proteins regulate VSMC migration and thereby intimal thickening.

APPROACH AND RESULTS

Wnt2 mRNA and protein expression were specifically increased in migrating mouse aortic VSMCs. Moreover, VSMC migration was induced by recombinant Wnt2 in vitro. Addition of recombinant Wnt2 protein increased Wnt1-inducible signaling pathway protein-1 (WISP-1) mRNA by ≈1.7-fold, via β-catenin/T-cell factor signaling, whereas silencing RNA knockdown of Wnt-2 reduced WISP-1 mRNA by ≈65%. Treatment with rWISP-1 significantly increased VSMC migration by ≈1.5-fold, whereas WISP-1 silencing RNA knockdown reduced migration by ≈40%. Wnt2 and WISP-1 effects were integrin-dependent and not additive, indicating that Wnt2 promoted VSMC migration via WISP-1. Additionally, Wnt2 and WISP-1 were significantly increased and colocated in human coronary arteries with intimal thickening. Reduced Wnt2 and WISP-1 levels in mouse carotid arteries from Wnt2(+/-) and WISP-1(-/-) mice, respectively, significantly suppressed intimal thickening in response to carotid artery ligation. In contrast, elevation of plasma WISP-1 via an adenovirus encoding WISP-1 significantly increased intimal thickening by ≈1.5-fold compared with mice receiving control virus.

CONCLUSIONS

Upregulation of Wnt2 expression enhanced WISP-1 and promoted VSMC migration and thereby intimal thickening. As novel regulators of VSMC migration and intimal thickening, Wnt2 or WISP-1 may provide a potential therapy for restenosis and vein graft failure.

Wnt Signaling in Cardiac Disease

Wnt signaling encompasses multiple and complex signaling cascades and is involved in many developmental processes such as tissue patterning, cell fate specification, and control of cell division. Consequently, accurate regulation of signaling activities is essential for proper embryonic development. Wnt signaling is mostly silent in the healthy adult organs but a reactivation of Wnt signaling is generally observed under pathological conditions. This has generated increasing interest in this pathway from a therapeutic point of view. In this review article, the involvement of Wnt signaling in cardiovascular development will be outlined, followed by its implication in myocardial infarct healing, cardiac hypertrophy, heart failure, arrhythmias, and atherosclerosis. The initial experiments not always offer consensus on the effects of activation or inactivation of the pathway, which may be attributed to (i) the type of cardiac disease, (ii) timing of the intervention, and (iii) type of cells that are targeted. Therefore, more research is needed to determine the exact implication of Wnt signaling in the conditions mentioned above to exploit it as a powerful therapeutic target.

Targeting clotting proteins in cancer therapy - progress and challenges

Cancer-associated thrombosis remains a significant complication in the clinical management of cancer and interactions of the hemostatic system with cancer biology continue to be elucidated. Here, we review recent progress in our understanding of tissue factor (TF) regulation and procoagulant activation, TF signaling in cancer and immune cells, and the expanding roles of the coagulation system in stem cell niches and the tumor microenvironment. The extravascular functions of coagulant and anti-coagulant pathways have significant implications not only for tumor progression, but also for the selection of appropriate target specific anticoagulants in the therapy of cancer patients.

Thrombosis formation on atherosclerotic lesions and plaque rupture

Atherosclerosis is a silent chronic vascular pathology that is the cause of the majority of cardiovascular ischaemic events. The evolution of vascular disease involves a combination of endothelial dysfunction, extensive lipid deposition in the intima, exacerbated innate and adaptive immune responses, proliferation of vascular smooth muscle cells and remodelling of the extracellular matrix, resulting in the formation of an atherosclerotic plaque. High-risk plaques have a large acellular lipid-rich necrotic core with an overlying thin fibrous cap infiltrated by inflammatory cells and diffuse calcification. The formation of new fragile and leaky vessels that invade the expanding intima contributes to enlarge the necrotic core increasing the vulnerability of the plaque. In addition, biomechanical, haemodynamic and physical factors contribute to plaque destabilization. Upon erosion or rupture, these high-risk lipid-rich vulnerable plaques expose vascular structures or necrotic core components to the circulation, which causes the activation of tissue factor and the subsequent formation of a fibrin monolayer (coagulation cascade) and, concomitantly, the recruitment of circulating platelets and inflammatory cells. The interaction between exposed atherosclerotic plaque components, platelet receptors and coagulation factors eventually leads to platelet activation, aggregation and the subsequent formation of a superimposed thrombus (i.e. atherothrombosis) which may compromise the arterial lumen leading to the presentation of acute ischaemic syndromes. In this review, we will describe the progression of the atherosclerotic lesion along with the main morphological characteristics that predispose to plaque rupture, and discuss the multifaceted mechanisms that drive platelet activation and subsequent thrombus formation. Finally, we will consider the current scientific challenges and future research directions.