Rac3 induces a molecular pathway triggering breast cancer cell aggressiveness: differences in MDA-MB-231 and MCF-7 breast cancer cell lines.

Background: Rho GTPases are involved in cellular functions relevant to cancer. The roles of RhoA and Rac1 have already been established. However, the role of Rac3 in cancer aggressiveness is less well understood.

Flavonoids purified from parsley inhibit human blood platelet aggregation and adhesion to collagen under flow.

Introduction: Blood platelets are directly involved in both haemostatic and pathologic thrombotic processes, through their adhesion, secretion and aggregation. In this study, we investigated the effect of genins (aglycone flavonoids without sugar group) isolated from parsley (Petroselinum crispum) leaves in vitro on human platelet aggregation and adhesion to a collagen-coated surface under physiologic flow conditions.

Materials And Methods: The aggregation and adhesion studies were monitored after pre-incubation of platelets with genins.

Platelet type III collagen binding protein (TIIICBP) presents high biochemical and functional similarities with kindlin-3.

Type III collagen binding protein (TIIICBP) was previously described as a platelet membrane protein that recognizes the KOGEOGPK peptide sequence within type III collagen. In order to better characterize this protein, we performed different approaches including mass spectrometry sequencing and functional experiments. This study leads to identify high biochemical and functional similarities between TIIICBP and kindlin-3, a member of a family of focal adhesion proteins.

Breast tumor cells transendothelial migration induces endothelial cell anoikis through extracellular matrix degradation.

Mutual interactions between human breast cancer cells and endothelial cells were studied in a model mimicking tumor cell intravasation. MDA-MB-231 tumor cells and human umbilical vein endothelial cells (HUVEC) were cocultured on opposite sides of a Transwell filter allowing tumor cell contacts with the basement membrane of the HUVEC forming endothelium and tumor cell transendothelial migration. Confocal microscopy analysis showed that transmigrating MDA-MB-231 cells lay under the HUVEC, thereby inducing HUVEC detachment and tumor cell-HUVEC contact-dependent apoptosis.

Inhibition of platelets and tumor cell adhesion by the disintegrin domain of human ADAM9 to collagen I under dynamic flow conditions.

This work aimed to investigate the role of the disintegrin domain of the human ADAM9 (ADAM9D) on the adhesion of breast tumor cells and platelets to collagen I, in a dynamic flow assay to simulate in vivo shear conditions. Recombinant ADAM9D was able to support tumor cell adhesion through binding to the beta1 integrin subunit and also to inhibit the invasion through matrigel in vitro. In a dynamic flow assay ADAM9D inhibited about 75% and 65% of MDA-MB-231 tumor cells and platelet adhesion to collagen I, respectively.

Parsley extract inhibits in vitro and ex vivo platelet aggregation and prolongs bleeding time in rats.

Many cardiovascular diseases are associated with an increase in blood platelet activity. In Morocco, parsley (Petroselinum crispum, Apiaceae) is one of the medicinal herbs used to treat cardiovascular diseases such as arterial hypertension. In this study, crude aqueous extract (CAE) of parsley was evaluated for its anti-platelet activity in experimental animals on platelet aggregation in vitro and ex vivo; and on bleeding time in vivo.

Matrix metalloproteinases are involved in both type I (apoptosis) and type II (autophagy) cell death induced by sodium phenylacetate in MDA-MB-231 breast tumour cells.

The effects of sodium phenylacetate (NaPa), an antitumoral molecule, on cell death and matrix metalloproteinase (MMP) activities and synthesis were investigated in two metastatic breast tumour cell lines, MDA-MB-231 and MDA-MB-435, cultured on three-dimensional type I collagen gels (3-D cultures). In both cell lines, NaPa inhibited cell proliferation and induced apoptotic cell death as measured by TUNEL assay, with an IC(30) of 20 mM and 10 mM for MDA-MB-231 and MDA-MB-435 cells, respectively. In MDA-MB-231 cells, NaPa also induced (i) an autophagic process evidenced by the appearance of autophagic vacuoles and an increased phosphatase acid activity, (ii) the formation of pseudopodia and (iii) an increase in MMP-1 and MMP-9 secretion without affecting MT1-MMP.

Circular dichroism studies of type III collagen mimetic peptides with anti- or pro-aggregant activities on human platelets.

We report the synthesis of collagen related peptides containing the peptide sequence Lys-Hyp-Gly-Glu-Hyp-Gly-Pro-Lys. The anti-thrombotic activity effects of different glycine mutations in this sequence were studied in regard with their different adopted conformations. The biological results could be correlated to the glycine propensity to adopt a more stable polyproline II helix conformation.

Ex vivo priming of endothelial progenitor cells with SDF-1 before transplantation could increase their proangiogenic potential.

Objective: As SDF-1 and its cognate receptor CXCR4 play a key role in the survival and mobilization of immature cells, we examined whether preconditioning of endothelial progenitor cells (EPCs) with SDF-1 could further promote their capacity to enhance angiogenesis.

Methods And Results: EPC exposure to 100 ng/mL SDF-1 for 30 min induced a proangiogenic phenotype, with cell migration and differentiation into vascular cords in Matrigel and increased their therapeutic potential in a nude mouse model of hindlimb ischemia. This pretreatment enhanced EPC adhesion to activated endothelium in physiological conditions of blood flow by stimulating integrin-mediated EPCs binding to endothelial cells.

Type III collagen mimetic peptides designed with anti- or pro-aggregant activities on human platelets.

We report the synthesis of collagen related peptides containing the peptide sequence Lys-Hyp-Gly-Glu-Hyp-Gly-Pro-Lys. The alpha-triple helix peptides behave as type III collagen analogues supporting platelet aggregation, while the homotrimer which does not exhibit a triple-helical conformation inhibits type III collagen-induced human platelet aggregation. The incorporation of the octapeptide sequence in type III collagen mimetic peptides may lead to the loss of the anti-thrombotic activity for a pro-thrombotic one.

Antithrombotic effect of the type III collagen-related octapeptide (KOGEOGPK) in the mouse.

Platelet adhesion to subendothelial types I and III collagens exposed upon vascular injury plays a crucial role in hemostasis and thrombosis. We previously identified a KOGEOGPK sequence (O for hydroxyproline) within type III collagen interacting with platelets, and demonstrated a strong inhibitory effect of the KOGEOGPK peptide on human platelet interactions with type III collagen in vitro. In the present study, we tested the antithrombotic effect of KOGEOGPK in vivo.

The platelet receptor for type III collagen (TIIICBP) is present in platelet membrane lipid microdomains (rafts).

Platelet interactions with collagen are orchestrated by the presence or the migration of platelet receptor(s) for collagen into lipid rafts, which are specialized lipid microdomains from the platelet plasma membrane enriched in signalling proteins. Electron microscopy shows that in resting platelets, TIIICBP, a receptor specific for type III collagen, is present on the platelet membrane and associated with the open canalicular system, and redistributes to the platelet membrane upon platelet activation. After platelet lysis by 1% Triton X-100 and the separation of lipid rafts on a discontinuous sucrose gradient, TIIICBP is recovered in lipid raft-containing fractions and Triton X-100 insoluble fractions enriched in cytoskeleton proteins.

Shear stress induced release of von Willebrand factor and thrombospondin-1 in HUVEC extracellular matrix enhances breast tumour cell adhesion.

Endothelial cells in vivo are exposed to blood shear forces and flow perturbations induce their activation. Such modifications of hemodynamic can be observed in patients with cancer. We have submitted endothelial cells (HUVEC) to shear stress (13 dynes/cm(2)) and isolated their extracellular matrix (ECM) prior perfusion with breast adenocarcinoma cells (MDA-MB-231) in whole blood at a shear rate of 1500 s(-1).

Differential Involvement of ERK2 and p38 in platelet adhesion to collagen.

We investigated the role of two MAP kinases, ERK2 and p38, in platelet adhesion and spreading over collagen matrix in static and blood flow conditions. P38 was involved in collagen-induced platelet adhesion and spreading in static adhesion conditions, whereas ERK2 was not. In blood flow conditions, with shear rates of 300 or 1500 s(-1), ERK2 and p38 displayed differential involvement in platelet adhesion, depending on the presence or absence of the von Willebrand factor (vWF).

Breast adenocarcinoma cell adhesion to the vascular subendothelium in whole blood and under flow conditions: effects of alphavbeta3 and alphaIIbbeta3 antagonists.

Tumour cell adhesion to vascular extracellular matrix (ECM), an important step of metastatic progression, is promoted by platelets. The aim of our study was to investigate, in whole blood under venous and arterial shear conditions, the respective role of tumour cell alphavbeta3 and platelet alphaIIbbeta3 integrins in MDA-MB-231 breast adenocarcinoma cell adhesion to human umbilical vein endothelial cell ECM. For that purpose, blood containing MDA-MB-231 cells was incubated with non-peptide antagonists specific for platelet alphaIIbbeta3 (lamifiban) or tumour cell alphavbeta3 (SB-273005).

Defective collagen-induced platelet activation in two patients with malignant haemopathies is related to a defect in the GPVI-coupled signalling pathway.

The occurrence of a thrombocytopathy concomitantly to the development of a malignant haemopathy has been reported for some time, but little is known about the mechanism(s) involved in the platelet dysfunction. Platelet glycoprotein VI (GPVI) has now been identified as a principal platelet receptor for collagen. In this paper, we report the cases of two patients with a myelodysplasia and a B lymphopathy, respectively, who presented with thrombocytopathy in relation to a defective GPVI-mediated platelet reactivity to collagen.