Dentin Matrix Protein 1 induces membrane expression of VE-cadherin on endothelial cells and inhibits VEGF-induced angiogenesis by blocking VEGFR-2 phosphorylation.

in Blood (2011), 117(8), 2515-26

Dentin matrix protein 1 (DMP1) is a member of the Small Integrin-Binding LIgand N-linked Glycoproteins (SIBLINGs) family, a group of proteins initially described as mineralized extracellular matrices ... [more ▼]

Dentin matrix protein 1 (DMP1) is a member of the Small Integrin-Binding LIgand N-linked Glycoproteins (SIBLINGs) family, a group of proteins initially described as mineralized extracellular matrices components. More recently, SIBLINGs have been implicated in several key steps of cancer progression, including angiogenesis. Although pro-angiogenic activities have been demonstrated for two SIBLINGs, the role of DMP1 in angiogenesis has not been addressed yet. We demonstrated that this extracellular matrix protein induced the expression of VE-cadherin, a key regulator of intercellular junctions and contact inhibition of growth of endothelial cells that is also known to modulate VEGFR-2 activity, the major high affinity receptor for VEGF. DMP1 induced VE-cadherin and p27(Kip1) expression followed by cell cycle arrest in human umbilical vein endothelial cells (HUVEC) in a CD44-dependent manner. VEGF-induced proliferation, migration and tubulogenesis responses were specifically blocked upon DMP1 pre-treatment of HUVEC. Indeed, subsequently to VE-cadherin induction, DMP1 inhibited VEGFR-2 phosphorylation and Src-mediated signaling. However, DMP1 did not interfere with bFGF-induced angiogenesis. In vivo, DMP1 significantly reduced laser-induced choroidal neovascularization lesions and tumor-associated angiogenesis. These data enable us to put DMP1 on the angiogenic chessboard for the first time and to identify this protein as a new specific inhibitor of VEGF-induced angiogenesis. [less ▲]

MicroRNA-21 Exhibits Antiangiogenic Function by Targeting RhoB Expression in Endothelial Cells.

in PLoS ONE (2011), 6(2), 16979

BACKGROUND: MicroRNAs (miRNAs) are endogenously expressed small non-coding RNAs that regulate gene expression at post-transcriptional level. The recent discovery of the involvement of these RNAs in the ... [more ▼]

BACKGROUND: MicroRNAs (miRNAs) are endogenously expressed small non-coding RNAs that regulate gene expression at post-transcriptional level. The recent discovery of the involvement of these RNAs in the control of angiogenesis renders them very attractive in the development of new approaches for restoring the angiogenic balance. Whereas miRNA-21 has been demonstrated to be highly expressed in endothelial cells, the potential function of this miRNA in angiogenesis has never been investigated. METHODOLOGY/PRINCIPAL FINDINGS: We first observed in endothelial cells a negative regulation of miR-21 expression by serum and bFGF, two pro-angiogenic factors. Then using in vitro angiogenic assays, we observed that miR-21 acts as a negative modulator of angiogenesis. miR-21 overexpression reduced endothelial cell proliferation, migration and the ability of these cells to form tubes whereas miR-21 inhibition using a LNA-anti-miR led to opposite effects. Expression of miR-21 in endothelial cells also led to a reduction in the organization of actin into stress fibers, which may explain the decrease in cell migration. Further mechanistic studies showed that miR-21 targets RhoB, as revealed by a decrease in RhoB expression and activity in miR-21 overexpressing cells. RhoB silencing impairs endothelial cell migration and tubulogenesis, thus providing a possible mechanism for miR-21 to inhibit angiogenesis. Finally, the therapeutic potential of miR-21 as an angiogenesis inhibitor was demonstrated in vivo in a mouse model of choroidal neovascularization. CONCLUSIONS/SIGNIFICANCE: Our results identify miR-21 as a new angiogenesis inhibitor and suggest that inhibition of cell migration and tubulogenesis is mediated through repression of RhoB. [less ▲]

ADAMTS-2 functions as anti-angiogenic and anti-tumoral molecule independently of its catalytic activity.

in Cellular & Molecular Life Sciences (2010)

ADAMTS-2 is a metalloproteinase that plays a key role in the processing of fibrillar procollagen precursors into mature collagen molecules by excising the amino-propeptide. We demonstrate that recombinant ... [more ▼]

ADAMTS-2 is a metalloproteinase that plays a key role in the processing of fibrillar procollagen precursors into mature collagen molecules by excising the amino-propeptide. We demonstrate that recombinant ADAMTS-2 is also able to reduce proliferation of endothelial cells, and to induce their retraction and detachment from the substrate resulting in apoptosis. Dephosphorylation of Erk1/2 and MLC largely precedes the ADAMTS-2 induced morphological alterations. In 3-D culture models, ADAMTS-2 strongly reduced branching of capillary-like structures formed by endothelial cells and their long-term maintenance and inhibited vessels formation in embryoid bodies (EB). Growth and vascularization of tumors formed in nude mice by HEK 293-EBNA cells expressing ADAMTS-2 were drastically reduced. A similar anti-tumoral activity was observed when using cells expressing recombinant deleted forms of ADAMTS-2, including catalytically inactive enzyme. Nucleolin, a nuclear protein also found to be associated with the cell membrane, was identified as a potential receptor mediating the antiangiogenic properties of ADAMTS-2. [less ▲]

New Biological Investigations on 3-Bromophenyl 6-Acetoxymethyl-2-oxo-2H-1-Benzopyran-3-Carboxylate as Anti-angiogenic Agent

in Drug Development Research (2010), 71

The development of blood vessels inside tumors is required to provide the nutrients and oxygen needed for tumor growth and to allow the spread of cancer cells at a distance to form metastasis ... [more ▼]

The development of blood vessels inside tumors is required to provide the nutrients and oxygen needed for tumor growth and to allow the spread of cancer cells at a distance to form metastasis. Angiogenesis is also implicated in ocular diseases like age-related macular degeneration. The present work describes the potential anti-angiogenic properties of a coumarinic derivative, 3-bromophenyl 6-acetoxymethyl-2-oxo-2H-1-benzopyran-3-carboxylate (IK9), previously described as a potent inhibitor of HT 1080 fibrosarcoma cell invasion in vitro and tumor growth in vivo. In vivo, ex vivo, and in vitro models were used to delineate the anti-angiogenic properties of IK9. The anti-angiogenic effect of IK9 was demonstrated in vivo in a choroidal neovascularization mice model and additionally ex vivo in a rat aortic ring assay where it was more active than the known matrix metalloproteinase inhibitor Ro 28-2653. IK9 did not affect apoptosis, proliferation, or endothelial cell invasiveness in vitro. These findings suggest a complex mechanism of action of the compound via direct or indirect effects on endothelial cell properties. This study identifies IK9 as a new potent inhibitor of angiogenesis and suggests its potential use as a therapeutic agent. [less ▲]

New biological investigations on the anti-angiogenic agent 3-bromophenyl 6-acetoxymethyl-2-oxo-2H-1-benzopyran-3-carboxylate: in search of its original mechanism of action

Poster (2008, May)

Anti-angiogenic therapy of exudative age-related macular degeneration: current progress and emerging concepts

in Trends in Molecular Medicine (2007), 13(8), 345-352

Age-related macular degeneration (AMD) is the leading cause of blindness in elderly patients. The more aggressive exudative form is characterized by abnormal blood-vessel development that occurs beneath ... [more ▼]

Age-related macular degeneration (AMD) is the leading cause of blindness in elderly patients. The more aggressive exudative form is characterized by abnormal blood-vessel development that occurs beneath the retina as a result of choroidal neovascularization (CNV). Vascular endothelial growth factor [VEGF) has emerged as the key mediator of CNV formation; this has led to intensive research on VEGF and the recent approval of anti-VEGF compounds by the US Food and Drug Administration. Despite this successful introduction of anti-angiogenic therapies into the clinical setting, there is still a lack of treatments that definitively reverse damaged vision. Here, we consider the importance of putative molecular targets other than VEGF that might have been underestimated. Emerging cellular mechanisms offer additional opportunities for innovative therapeutic approaches. [less ▲]

Tumoral and choroidal vascularization: differential cellular mechanisms involving plasminogen activator inhibitor type I.

in American Journal of Pathology (2007), 171(4), 1369-80

An adequate balance between serine proteases and their plasminogen activator inhibitor-1 (PAI-1) is critical for pathological angiogenesis. PAI-1 deficiency in mice is associated with impaired choroidal ... [more ▼]

An adequate balance between serine proteases and their plasminogen activator inhibitor-1 (PAI-1) is critical for pathological angiogenesis. PAI-1 deficiency in mice is associated with impaired choroidal neovascularization (CNV) and tumoral angiogenesis. In the present work, we demonstrate unexpected differences in the contribution of bone marrow (BM)-derived cells in these two processes regulated by PAI-1. PAI-1(-/-) mice grafted with BM-derived from wild-type mice were able to support laser-induced CNV formation but not skin carcinoma vascularization. Engraftment of irradiated wild-type mice with PAI-1(-/-) BM prevented CNV formation, demonstrating the crucial role of PAI-1 delivered by BM-derived cells. In contrast, the transient infiltration of tumor transplants by local PAI-1-producing host cells rather than by BM cells was sufficient to rescue tumor growth and angiogenesis in PAI-1-deficient mice. These data identify PAI-1 as a molecular determinant of a local permissive soil for tumor angiogenesis. Altogether, the present study demonstrates that different cellular mechanisms contribute to PAI-1-regulated tumoral and CNV. PAI-1 contributes to BM-dependent choroidal vascularization and to BM-independent tumor growth and angiogenesis. [less ▲]

Rôle des protéinases et de leurs inhibiteurs dans les formes associées à une néovascularisation anormale sous-rétinienne. Caractérisation par l’étude de modèles animaux transgéniques et développements thérapeutiques.

Doctoral thesis (2005)

La dégénérescence maculaire liée à l'âge (DMLA) est la principale cause de perte visuelle chez les personnes de plus de 70 ans dans le monde occidental. Cette cécité résulte de la perte de fonction de la ... [more ▼]

La dégénérescence maculaire liée à l'âge (DMLA) est la principale cause de perte visuelle chez les personnes de plus de 70 ans dans le monde occidental. Cette cécité résulte de la perte de fonction de la macula (au centre de la rétine) qui est responsable de la vision centrale. Cette dégénérescence réprésente un handicap social indéniable et une perte de liberté pour ces personnes atteintes, car elle affecte des activités telles que la conduite, la lecture ou tout simplement la reconnaissance d’un visage. La pathogénie de cette affection est complexe et peu comprise. La forme la plus grave de cette maladie est associée à une poussée vasculaire (angiogenèse) vers l'espace sous-rétinien qui entraîne une fibrose avec perte des photorécepteurs. La plupart des lésions ne sont pas curables par photocoagulation laser et les stratégies thérapeutiques actuelles sont insuffisantes. Nous avons étudié, dans notre laboratoire, les mécanismes moléculaires de l’angiogenèse. Ce processus invasif requiert la digestion de la matrice extracellulaire avant la prolifération et la migration des capillaires. Deux systèmes enzymatiques sont principalement impliqués dans la digestion tissulaire : le système plasminogène/plasmine et les métalloprotéinases matricielles (MMPs). 1) Le système protéolytique activateur du plasminogène/plasmine : Afin d'évaluer la pertinence biologique de ce système dans l'angiogenèse sous-rétinienne, nous avons mis au point un modèle de néovascularisation choroidienne à l'aide d'un impact laser à l'argon chez des souris déficientes pour une série de gènes fondamentaux de ce système, comparées à des souris normales. Nos observations mettent en évidence le rôle essentiel du PAI-1 dans la néovascularisation sous-rétinienne et contribuent à expliquer l'aspect multifonctionnel du PAI-1 dans l'angiogenèse. 2) Les métalloprotéinases matricielles (MMPs) : Les métalloprotéinases matricielles (MMPs) participent au remodelage normal tissulaire et sont impliquées dans un large éventail de phénomènes physiologiques et pathologiques, tels que l'invasion cellulaire tumorale, la cicatrisation et l'angiogenèse. Nous avons appliqué notre modèle expérimental à des souris déficientes pour deux types de MMP (MMP-2 et MMP-9). La déficience en MMP-2 et -9 inhibe la néovascularisation sous-rétinienne induite par laser, soulignant l’importance de cette enzyme in vivo. Ces études laissent entrevoir des perspectives thérapeutiques dans la lutte contre la DMLA par l’utilisation d’inhibiteur spécifiques des ces MMPs. En conclusion, ces différents aspects de notre étude ouvrent des perpectives de développements thérapeutiques. Ils démontrent l’importance des MMP-2, MMP-9 et de PAI-1 dans la néovascularisation sous-rétinienne. L’inhibition spécifique de ces enzymes laisse entrevoir des espoirs dans le traitement curatif de la dégénérescence maculaire liée à l’âge. Malheureusement de grandes lacunes existent encore quand aux perturbations métaboliques à l’origine de la DMLA, ce qui est l’objet de cette étude. [less ▲]

ADAMTS-2, a metalloproteinase containing a disintegrin domain and thrombospondin type I repeats, a new regulator of angiogenesis

in Journal of Vascular Research (2005), 42(Suppl. 2), 76

Enzymes of the ADAMTS family are closely related to MMPs and ADAMs. They further contain specific domains, such as the “ThromboSpondin type I” (TSP1) repeats able to strongly repress angiogenesis. The ... [more ▼]

Enzymes of the ADAMTS family are closely related to MMPs and ADAMs. They further contain specific domains, such as the “ThromboSpondin type I” (TSP1) repeats able to strongly repress angiogenesis. The primary function of ADAMTS-2 is to process procollagen type I, II, III and V into mature molecules by excising the amino-propeptide. We further hypothesized that it could modulate angiogenesis through its TSP1 repeats. Recombinant ADAMTS-2 induced morphological changes in HUVEC and HMEC cultured on gelatin, collagen and fibronectin. It also significantly reduced their proliferation, attachment and spreading. Similar effects were observed when using inactive ADAMTS-2 mutated at the Zn++-binding catalytic site. ADAMTS-2 did not alter the initial steps of formation of capillary-like structures by HUVEC in vitro. However, these structures appeared more rapidly disrupted in presence of ADAMTS-2 than in control conditions. Immunostaining with monoclonal antibodies against ADAMTS-2 indicate that it is tightly immobilized at the endothelial cell surface by an heparin-sensitive binding. With the aim to identify mechanism(s)leading to the modulation of angiogenesis by ADAMTS-2, we investigated various signalling pathways critical for EC. Phosphorylation status of FAK was not altered by ADAMTS-2 while a downregulation of phosphorylation of p42/44 MAPK was observed. Our data suggest that ADAMTS-2 reduces angiogenesis by regulating endothelial cell adhesion and proliferation, and by alteration of the stability of the capillary-like structures. These effects do not seem to be mediated by an integrin-dependent signaling pathway. Choroidal neovascularization induced in TS2+/+ or TS2-/- mice by LASER burns was used as in vivo model. Several genes involved in the healing and angiogenesis processes (fibrillar collagens, VEGF, TGF, CTGF, …) were not differently regulated in TS2+/+ and TS2-/- mice 5 days after the LASER impact. Wound capillaries visualized by confocal microscopy after FITC-conjugated dextran injection, were significantly increased (p<0,05) in TS2-/- mice suggesting an increased angiogenic response in the KO animals. The results obtained in in vivo and in vitro models indicate that ADAMTS-2 is involved in the control of angiogenesis. Additional investigations are being performed to determine which domain(s) of the molecule is (are) antiangiogenic and to identify the mechanism(s) underlying this regulatory function. [less ▲]

Dose-dependent modulation of choroidal neovascularization by plasminogen activator inhibitor type 1: Implications for clinical trials

in Investigative Ophthalmology & Visual Science (2003), 44(6), 2791-2797

PURPOSE. To explain the conflicting reports about the influence of plasminogen activator inhibitor type (PAI-1) on pathologic angiogenesis, such as occurs during the exudative form of age-related macular ... [more ▼]

PURPOSE. To explain the conflicting reports about the influence of plasminogen activator inhibitor type (PAI-1) on pathologic angiogenesis, such as occurs during the exudative form of age-related macular degeneration. METHODS. The expression of PAI-1 mRNA was analyzed in human and murine choroidal neovascularization (CNV) by RTPCR. The influences of increasing doses of recombinant PAI-1 were evaluated by daily intraperitoneal injections in PAI-1-1-and wild-type animals with a model of laser-induced CNV. The double mechanism of action of PAI-1 (proteolytic activity inhibition versus vitronectin binding) was explored by immunohistochemical localization of fibrinogen/fibrin and by injection of recombinant PAI-1 protein defective for vitronectin binding or with adenoviral vectors bearing a mutated binding-deficient PAI-1 gene. RESULTS. PAI-1 expression was present in human CNV and strongly induced in the course of experimental subretinal neovascularization. Daily injections of recombinant PAI-1 proteins in control and PAI-1(-/-) animals demonstrated that PAI-1 could exhibit both pro- and antiangiogenic effects, dependent on the dose. PAI-1 mutants defective for vitronectin binding were used to show that PAI-1 promotes choroidal pathologic angiogenesis merely through its antiproteolytic activity. CONCLUSIONS. These observations may help to reconcile reports with opposite results regarding the effects of PAI-1 on angiogenesis and certainly warn against uncontrolled use of PAL I modulating drugs in clinical trials. [less ▲]