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| 2. |
- Roche, Francis, et al.
(författare)
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Histidine-rich glycoprotein blocks collagen-binding integrins and adhesion of endothelial cells through low-affinity interaction with alpha 2 integrin
- 2015
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Ingår i: Matrix Biology. - : Elsevier BV. - 0945-053X .- 1569-1802. ; 48, s. 89-99
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Tidskriftsartikel (refereegranskat)abstract
- The plasma protein histidine-rich glycoprotein (HRG) affects the morphology and function of both endothelial cells (ECs) and monocytes/macrophages in cancer. Here, we examined the mechanism of action of HRG's effect on ECs. HRG suppressed adhesion, spreading and migration of ECs specifically on collagen I (COL I) whereas ECs seeded on other extracellular matrix proteins were insensitive to HRG. HRG did not bind specifically to COL I or to the α-integrin binding site on collagen, GFOGER. Furthermore, HRG's inhibition of EC adhesion was not dependent upon heparan sulfate (HS) moieties as heparitinase-treated ECs remained sensitive to HRG. C2C12 cells expressing α2 integrin, the major collagen-binding α-integrin subunit in ECs, showed increased binding of HRG compared with wild type C2C12 cells lacking the α2 subunit. Recombinant α2 I-domain protein bound HRG and to a higher extent when in active conformation. However, the α2 I-domain bound weakly to HRG compared with COL I and the purified α2β1 ectodomain complex failed to retain HRG. We conclude that HRG binds to α2 integrin through low-affinity interactions in a HS-independent manner, thereby blocking EC-adhesion to COL I.
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| 3. |
- Tugues, Sònia, et al.
(författare)
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Genetic deficiency in plasma protein HRG enhances tumor growth and metastasis by exacerbating immune escape and vessel abnormalization
- 2012
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Ingår i: Cancer Research. - 0008-5472 .- 1538-7445.
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Tidskriftsartikel (refereegranskat)abstract
- Histidine-rich glycoprotein (HRG) is a 75 kDa heparin-binding plasma protein implicated in the regulation of tumor growth and vascularization. In this study, we show that hrg-/- mice challenged with fibrosarcoma or pancreatic carcinomas grow larger tumors with increased metastatic properties. Compared with wild type mice, fibrosarcomas in hrg-/- mice were more hypoxic, necrotic and less perfused, indicating enhanced vessel abnormalization. HRG-deficiency was associated with a suppressed anti-tumor immune response, with both increased infiltration of M2-marker-expressing macrophages and decreased infiltration of dendritic cells and cytotoxic T cells. Analysis of transcript expression in tumor-associated as well as peritoneal macrophages from hrg-/- mice revealed an increased expression of genes associated with a pro-angiogenic and immunoinhibitory phenotype. In accordance, expression arrays performed on HRG-treated peritoneal macrophages showed induction of genes involved in extracellular matrix biology and immune responsiveness. In conclusion, our findings demonstrate that macrophages are a direct target of HRG. HRG loss influences macrophage gene regulation, leading to excess stimulation of tumor angiogenesis, suppression of tumor immune response, and increased tumor growth and metastatic spread.
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| 4. |
- Tugues, Sònia, et al.
(författare)
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Histidine-Rich Glycoprotein Uptake and Turnover Is Mediated by Mononuclear Phagocytes.
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:9, s. e107483-
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Tidskriftsartikel (refereegranskat)abstract
- Histidine-rich glycoprotein (HRG) is implicated in tumor growth and metastasis by regulation of angiogenesis and inflammation. HRG is produced by hepatocytes and carried to tissues via the circulation. We hypothesized that HRG's tissue distribution and turnover may be mediated by inflammatory cells. Biodistribution parameters were analyzed by injection of radiolabeled, bioactive HRG in the circulation of healthy and tumor-bearing mice. 125I-HRG was cleared rapidly from the blood and taken up in tissues of healthy and tumor-bearing mice, followed by degradation, to an increased extent in the tumor-bearing mice. Steady state levels of HRG in the circulation were unaffected by the tumor disease both in murine tumor models and in colorectal cancer (CRC) patients. Importantly, stromal pools of HRG, detected in human CRC microarrays, were associated with inflammatory cells. In agreement, microautoradiography identified 125I-HRG in blood vessels and on CD45-positive leukocytes in mouse tissues. Moreover, radiolabeled HRG bound in a specific, heparan sulfate-independent manner, to differentiated human monocytic U937 cells in vitro. Suppression of monocyte differentiation by systemic treatment of mice with anti-colony stimulating factor-1 neutralizing antibodies led to reduced blood clearance of radiolabeled HRG and to accumulation of endogenous HRG in the blood. Combined, our data show that mononuclear phagocytes have specific binding sites for HRG and that these cells are essential for uptake of HRG from blood and distribution of HRG in tissues. Thereby, we confirm and extend our previous report that inflammatory cells mediate the effect of HRG on tumor growth and metastatic spread.
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| 5. |
- Tugues, Sonia, et al.
(författare)
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Tetraspanin CD63 Promotes Vascular Endothelial Growth Factor Receptor 2-beta 1 Integrin Complex Formation, Thereby Regulating Activation and Downstream Signaling in Endothelial Cells in Vitro and in Vivo
- 2013
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:26, s. 19060-19071
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Tidskriftsartikel (refereegranskat)abstract
- CD63 is a member of the transmembrane-4 glycoprotein superfamily (tetraspanins) implicated in the regulation of membrane protein trafficking, leukocyte recruitment, and adhesion processes. We have investigated the involvement of CD63 in endothelial cell (EC) signaling downstream of beta 1 integrin and VEGF. We report that silencing of CD63 in primary ECs arrested capillary sprouting and tube formation in vitro because of impaired adhesion and migration of ECs. Mechanistically, CD63 associated with both beta 1 integrin and the main VEGF receptor on ECs, VEGFR2. Our data suggest that CD63 serves to bridge between beta 1 integrin and VEGFR2 because CD63 silencing disrupted VEGFR2-beta 1 integrin complex formation identified using proximity ligation assays. Signaling downstream of beta 1 integrin and VEGFR2 was attenuated in CD63-silenced cells, although their cell surface expression levels remained unaffected. CD63 was furthermore required for efficient internalization of VEGFR2 in response to VEGF. Importantly, systemic delivery of VEGF failed to potently induce VEGFR2 phosphorylation and downstream signaling in CD63-deficient mouse lungs. Taken together, our findings demonstrate a previously unrecognized role for CD63 in coordinated integrin and receptor tyrosine kinase signaling in vitro and in vivo.
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| 6. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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