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Biomedical subjects

J Plouet

Publications and source records attributed to J Plouet.

At least 19 recordsLinked to original sources
PubMed2001

Human melanoma cells inhibit the earliest differentiation steps of human Langerhans cell precursors but failed to affect the functional maturation of epidermal Langerhans cells.

Tumour-derived factors suppress differentiation and function of in vitro generated DC. Here, we investigate the effect of two melanoma clones differing in their invasive and metastatic properties on the generation and/or functional maturation of human epidermal LC. LC were generated from CD34(+) cord blood progenitors under GM-CSF/TNF-alpha/TGF-beta 1. CD34(+) cells were co-cultured with or without melanoma cells using Transwell dishes. After 11 days of co-culture, CD34(+)-derived cells display a non-adherent undifferentiated morphology, a high level of monocytic CD14 marker, a down-regulated expression of LC markers (CD1a, E-cadherin) and DC markers (CD40, CD80, CD54, CD58, CD83, CD86, HLA-DR, HLA-class I). These cells were less potent than control LC in inducing allogeneic T cell proliferation. The generation of the CD14(+) population was correlated with a decrease in the CD1a(+) population, without any statistical differences between the two clones. Melanoma cells diverted the differentiation of CD34(+) cells towards a dominant CD14(+) population only if the progenitors were in an early growth phase. IL-10, TGF-beta 1 and VEGF were not responsible for these effects, as assessed by using blocking antibodies. By contrast, co-culture of fresh epidermal LC with melanoma cells did not affect their phenotype and function. Our data demonstrate that melanoma cells inhibit the earliest steps of LC differentiation, but failed to affect the functional maturation of epidermal LC. This suggests that melanoma cells participate in their own escape from immunosurveillance by preventing LC generation in the local cutaneous microenvironment.

Antigens, CD34↗
PubMed2000

[Anti-angiogenesis strategies in cancer].

It is generally accepted that tumor development requires the secretion by cancer cells of soluble mediators which activate the formation of new vessels, called "Tumor Angiogenic Factors". The intense quest for identifying these factors has recently been confirmed by strong experimental data. The discovery in 1989 of the Vascular Endothelial Growth Factor VEGF and of new proteases had led to the identification of the key actors of tumor angiogenesis. The elucidation of their mechanisms of action allowed to design new therapeutic strategies already confirmed by preclinical trials. There are now almost twenty molecules which are under clinical investigation in man.

Angiogenesis Inducing Agents↗
PubMed1999

Inhibition of in vitro angiogenesis by platelet factor-4-derived peptides and mechanism of action.

In this study, we examined in detail the interaction of platelet factor-4 (PF-4) with fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor (VEGF) and the effect of PF-4-derived synthetic peptides. We show that a peptide between amino acids 47 and 70 that contains the heparin-binding lysine-rich site inhibits FGF-2 or VEGF function. This is based on the following observations: PF-4 peptide 47-70 inhibited FGF-2 or VEGF binding to endothelial cells; it inhibited FGF-2 or VEGF binding to FGFRs or VEGFRs in heparan sulfate-deficient CHO cells transfected with FGFR1 (CHOFGFR1) or VEGFR2 (CHOmVEGFR2) cDNA; it blocked proliferation or tube formation in three-dimensional angiogenesis assays; and, finally, it competed with the direct association of (125)I-PF-4 with FGF-2 or VEGF, respectively, and inhibited heparin-induced FGF-2 dimerization. A shorter C-terminal peptide (peptide 58-70), which still contained the heparin-binding lysin-rich site, had no effect. Peptide 17-58, which is located in the central part of the molecule, although it does not inhibit FGF-2 or VEGF binding or biologic activity in endothelial cells, inhibited heparin-dependent binding of (125)I-FGF-2 or (125)I-VEGF to CHOmFGFR1 or CHOmVEGFR2 cells, respectively. Shorter peptides (peptides 34-58 and 47-58) did not show any of these effects.

Animals↗
PubMed1999

[Impact on tumor angiogenesis and tumor progression of expression of the 18 kd and 24 kd isoforms of FGF-2].

The role of FGF-2 in tumor progression and tumor cell invasiveness was investigated using the rat bladder carcinoma cells NBT-II, which do not constitutively express FGF-2 or its membrane-spanning receptor. The NBT-II cells were transfected using expression vectors encoding either the 18 kD or the 24 kD isoform of FGF-2. The 24 kD isoform contains a nuclear localization signal. The transfected NBT-II cells that expressed 18 kD FGF-2 produced and secreted this factor as the biologically active form and retained an epithelial morphology. When injected to nude mice, the tumorigenic potential of these cells was not increased over that of non-transfected NBT-II cells; however, although the time to tumor development was long, the tumors were highly vascularized, indicating secretion of the angiogenic factor FGF-2. The transfected NBT-II cells that expressed 24 kD FGF-2 varied in their morphological appearance and did not secrete FGF-2; immunofluorescence and Western-blot studies showed that the FGF-2 was mainly intranuclear. When injected to nude mice, these cells produced tumors and migrated not only to the lymph nodes but also to the lungs where they produced metastases. In aggregate, these data indicate that stimulation of angiogenesis is not sufficient to increase tumor growth and that nuclear FGF-2 acts as a tumorigenic and metastasis-promoting factor in the NBT-II carcinoma model.

Animals↗
PubMed1997

FGF-2 and FGF-1 expressed in rat bladder carcinoma cells have similar angiogenic potential but different tumorigenic properties in vivo.

The comparative biological properties of NBT-II cells, a rat bladder carcinoma cell line constitutively expressing FGF-1 and FGF-2 were analysed in nude mice. FGF-1 is not secreted by the transfected cells unless the cDNA contains a signal sequence; conversely, NBT-II cells transfected with FGF-2 coding sequence produce and secrete the factor in a biologically active form. Bovine brain capillary endothelial cells are stimulated to proliferate upon addition of medium conditioned by the FGF-2-producing cells and this activity can be abrogated by the addition of anti-FGF-2 blocking antibodies. In addition, the FGF-2-containing medium, which cannot stimulate NBT-II cells due to absence of appropriate receptors, is able to induce scattering of NBT-II cells expressing the FGFR1. It has been reported previously that FGF-1-producing cells are highly tumorigenic in nude mice and induce carcinoma with a period of latency reduced from 6 to 5 weeks when compared to parental NBT-II cells. In contrast, NBT-II cells producing FGF-2 are no more tumorigenic than parental cells, indicating that FGF-1 and FGF-2 have different oncogenic properties in carcinoma. FGF-1 and FGF-2 are potent antiogenic factors that trigger the host endothelial cells. VEGF, another potent angiogen was found to be expressed in small amounts by NBT-II cells and to be expressed in reduced amount in the FGF-producing cells. In the NBT-II system in vivo FGF-1 and FGF-2 are highly and comparatively angiogenic in the resultant carcinoma and this occurs in the absence of production of significant amounts of VEGF by the carcinoma cells. Taken together, our results indicate that activated angiogenesis is not sufficient for rapid tumor expansion. FGF-1 behaves as a tumorigenic factor in the NBT-II bladder carcinoma cell model, whereas expression and secretion of large amounts of FGF-2 are not sufficient for increasing tumor growth.

Animals↗
PubMed1997

Vascular endothelial growth factor confers a growth advantage in vitro and in vivo to stromal cells cultured from neonatal hemangiomas.

Neonatal hemangioma is a common benign proliferation of unorganized structures containing stromal and capillary endothelial cells. We tested the hypothesis that such cell proliferation might result from the release by stromal cells of endothelial cell mitogens. Stromal cells cultured from biopsies of surgically removed life-threatening hemangiomas released an endothelial cell mitogen in vitro that was indistinguishable from vascular endothelial growth factor (VEGF) based on independent criteria such as affinity chromatography for heparin or anti-VEGF IgG and radioreceptor assay. A functional product of the KDR gene encoding a cognate VEGF receptor was also expressed by these stromal cells. Transient transfection with antisense oligonucleotides targeted on the translation initiation codon of KDR abolished its tyrosine phosphorylation and mitogenic response of neonatal hemangioma cells to VEGF, confirming the existence of an autocrine loop of proliferation. When grafted in nude mice, these stromal cells elicited an angiogenic response that was blocked by neutralizing anti-VEGF IgG. These results might provide a clue to the importance of stromal cells in the pathogeny of neonatal hemangiomas.

Animals↗
PubMed1996

Vascular endothelial growth factor and retinal neovascularisation: a new therapeutic approach for diabetic retinopathy.

Since the pioneer work of Michaelson in 1947 reporting that retinal ischemia induces the release of soluble angiogenic compounds, numerous studies have been conducted to identify the molecular structure of such messengers. In the early 1980s, the deciphering of angiogenic factor-signaling pathways and their description in the retina focused attention on growth factors. Vascular endothelial growth factor, the major candidate identified in 1992, induces in vivo angiogenesis and vascular permeability. Its expression is enhanced in vitro by hypoxia and hypoglycaemia; and its immunoreactivity is increased in diabetic patients. A decrease in its bioavailability reduces the intensity of neovascularization.

Animals↗
PubMed1994

Detection of vascular endothelial growth factor messenger RNA and vascular endothelial growth factor-like activity in proliferative diabetic retinopathy.

OBJECTIVE: To study the involvement of eight angiogenic growth factors that have been identified so far in the literature, especially vascular endothelial growth factor, in proliferative diabetic retinopathy. METHODS: Samples of neovascular membranes were obtained from diabetic patients; these samples, excised at vitrectomy, were used to study the expression of messenger RNA of the angiogenic factors by using the method of the reverse transcription-polymerase chain reaction. Vitreous aspirates that were taken from diabetic and control patients were used to quantify vascular endothelial growth factor-like activity with a competitive radioreceptor assay. RESULTS: Of the eight angiogenic factors studied, vascular endothelial growth factor was the only one that was always expressed in the samples of neovascular membranes. Furthermore, vascular endothelial growth factor receptor-binding activity was greater in vitreous aspirates that were obtained from diabetic patients than in samples that were taken from control patients (P < .01). CONCLUSION: Vascular endothelial growth factor seems to be an appropriate candidate for mediating retinal diabetic neovascularization.

Adolescent↗
PubMed1994

Vasculotropin-VEGF stimulates retinal capillary endothelial cells through an autocrine pathway.

PURPOSE: To determine whether bovine retinal endothelial cells (BRECs) bind, synthesize, and respond to vasculotropin-vascular endothelial growth factor (VAS-VEGF). METHODS: Cultured BRECs were tested for their ability to bind 125I VAS-VEGF and their response to the growth and migration-promoting effect of VAS-VEGF. Total RNAs extracted from BRECs were reverse transcribed and amplified by polymerase chain reaction using VAS-VEGF primers. The translation was assessed by a Western blot analysis and a radioreceptor assay in the BREC-conditioned medium. Neutralization with anti-VAS-VEGF antibodies ascertained the autocrine role of VAS-VEGF. RESULTS: BRECs bind VAS-VEGF on two high-affinity binding sites (apparent Kd of 2 and 56 pM) and can proliferate and migrate upon the addition of recombinant VAS-VEGF. Furthermore, BRECs synthesize and secrete into their own culture medium a mitogen related to VAS-VEGF as far as two factors are concerned: chromatographic behavior on heparin-affinity columns, and cross-reactivity with recombinant VAS-VEGF to the binding to its receptors or antibodies. Neutralization of the purified conditioned medium with anti-VAS-VEGF antibodies revealed that VAS-VEGF can act on BRECs through an autocrine pathway. CONCLUSIONS: This is the first description of an autocrine regulation of endothelial cell growth by VAS-VEGF that could be involved in the pathogenesis of retinal neovascularization.

Animals↗
PubMed1993

Endothelin 1 is a growth factor for corneal endothelium.

Endothelin 1 (ET1) is a newly discovered peptide found in various tissues, which exerts its biological effects through autocrine or paracrine pathways. Its presence and binding sites in the anterior chamber of the eye have recently been reported. Using a binding assay, we found the presence of a single class of receptors for ET1 on bovine corneal endothelial cells, whereas no ET1 could be detected in their conditioned medium. ET1 receptors appeared to be involved in BCE cell proliferation and migration. Furthermore, ET1 effects were additive to that of basic Fibroblast Growth Factor. Thus, we have shown for the first time that ET1 acts as a growth factor on corneal endothelium through a paracrine mediated action. This research suggests that ET1 has a role in corneal endothelium physiology and might provide a new field of investigation in the pharmacology of corneal endothelial healing.

Animals↗
PubMed1991

Interaction of vasculotropin/vascular endothelial cell growth factor with human umbilical vein endothelial cells: binding, internalization, degradation, and biological effects.

Vasculotropin/vascular endothelial cell growth factor (VAS/VEGF) is a newly purified growth factor with a unique specificity for vascular endothelial cells. We have investigated the interactions of VAS/VEGF with human umbilical vein endothelial cells (HUVE cells). 125I-VAS/VEGF was found to HUVE cells in a saturable manner with a half-maximum binding at 2.8 ng/ml. Scatchard analysis did show two classes of high-affinity binding sites. The first class displayed a dissociation constant of 9 pM with 500 sites/cell. The dissociation constant and the number of binding sites of the second binding class were variable for different HUVE cell cultures (KD = 179 +/- 101 pM, 5,850 +/- 2,950 sites/cell). Half-maximal inhibition of 125I-VAS/VEGF occurred with a threefold excess of unlabeled ligand. Basic fibroblast growth factor (bFGF) and heparin did not compete with 125I-VAS/VEGF binding. In contrast, suramin and protamin sulfate completely displaced 125I-VAS/VEGF binding from HUVE cells. VAS/VEGF was shown to be internalized in HUVE cells. Maximum internalization (55% of total cell-associated radioactivity) was observed after 30 min. 125I-VAS/VEGF was completely degraded 2-3 hr after binding. At 3 hr, the trichloroacetic acid (TCA)-soluble radioactivity accumulated in the medium was 60% of the total radioactivity released by HUVE cells. No degradation fragment of 125I-VAS/VEGF was observed. Chloroquine completely inhibited degradation. VAS/VEGF was able to induce angiogenesis in vitro in HUVE cells. However, it did not significantly modulate urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor (PAI-1), and tissue factor (TF). Prostacyclin production was only stimulated at very high VAS/VEGF concentrations. Taken together, these results indicate that VAS/VEGF might be a potent inducer of neovascularization resulting from a direct interaction with endothelial cells. The angiogenic activity seems to be independent of the plasminogen activator or inhibitor system.

Cells, Cultured↗
PubMed1991

[Mitogenic activity of vasculotropin for peripheral human lymphocytes].

Vasculotropin is a growth factor with a unique specificity for vascular derived endothelial cells. We report that normal human peripheral lymphocytes represent another target for vasculotropin. The mitogenic activity of the medium conditioned by these cells cultured in the presence of Concanavalin A is potentiated by vasculotropin. This effect is exerted more likely through interactions with the soluble mediators rather than through the VAS receptors since VAS binds equally to Concanavalin A stimulated and to unstimulated lymphocytes.

Concanavalin A↗
PubMed1991

[Vasculotropin: a new angiogenic growth factor].

A new growth factor, provisionally named vasculotropin (VAS), with a unique specificity for vascular endothelial cells has been purified to homogeneity. VAS is a 45 kDa glycosylated homodimeric protein. Cloning of the VAS gene has evidenced a sequence homology with A and B chains of Platelet-Derived Growth Factor. The receptor on vascular endothelial cells has been shown to be a 180 kDa protein. A 110 kDa receptor has been found on cells that do not respond to the mitogenic effect of vasculotropin, such as lens epithelial cells or corneal endothelial cells.

Growth Inhibitors↗
PubMed1990

Iris-derived melanocytes contain a growth factor that resembles basic fibroblast growth factor.

A melanocyte growth stimulating factor has been purified from bovine iris melanocytes and identified as being closely related to the basic form of fibroblast growth factor (bFGF). This conclusion was based on the behavior of the melanocyte-derived growth factor when submitted to heparin-Sepharose affinity chromatography, as well as on its ability to cross-react with bFGF in radioimmuno- and radioreceptor assays. The ability of neutralizing bFGF antibodies to block cell proliferation in response to the melanocyte growth factor further confirms that it is closely related to bFGF. Since melanocytes express the 3.7-kb and 7.0-kb bFGF transcript, the possibility exists that uncontrolled expression of melanocyte-derived bFGF could be involved in the malignant transformation of melanocytes into melanoma cells.

Animals↗
PubMed1990

Specific binding of vasculotropin to bovine brain capillary endothelial cells.

Recently, a new growth factor was purified to homogeneity; its biological activity appeared to be restricted to vascular endothelial derived cells. As it was also angiogenic in vivo, it was provisionally named vasculotropin. An iodination procedure used to label vasculotropin did not damage the molecule; it was thus possible to undertake binding studies. The binding of iodinated vasculotropin to bovine brain capillary endothelial cells reached saturation at 7 ng/ml and half maximal binding occurred at 1.5 ng/ml. Scatchard analysis of the data demonstrated 2 classes of binding sites with apparent dissociation constants of 4 and 41 pM and 600 and 4,100 sites per cell respectively. The interaction was specific since an excess of unlabelled vasculotropin, but no Fibroblast Growth Factor or Transforming Growth Factor Beta almost totally abolished the binding of the tracer. A sensitive radioreceptor-assay convenient for measuring vasculotropin in biological samples is described.

Animals↗