Expression of galectins on microvessel endothelial cells and their involvement in tumour cell adhesion

Lactoside-binding lectins (galectins) with molecular weights of about 14.5 kDa (galectin-1) and 29–35 kDa (galectin-3) bind preferentially to polylactosaminoglycan-containing glycoconjugates and have been found on the surface of tumour cells and implicated in cell-cell and cell-extracellular matrix adhesion and metastasis. We have demonstrated by immunoblotting that both galectin-1 and galectin-3 are present in extracts of endothelial cells cultured from bovine aorta, rat lung, mouse lung and mouse brain microvessels, whereas mouse hepatic sinusoidal endothelial cells expressed primarily galectin-1. These galectins were also localized by indirect immunofluorescent labelling on the surface of the different endothelial cells in culture and by immunohistochemical staining in human tissuesin vivo. Anti-galectin-1 antibodies inhibited the adhesion of liver-preferring murine RAW117-H10 large-cell lymphoma cells to hepatic sinusoidal endothelial cells or lung microvessel endothelial cellsin vitro. The data indicate that galectin-1 is expressed on the extracellular surface of endothelial cells and can mediate in part the adhesion of RAW117-H10 cells to liver microvessel endothelial cells.     

Differential expression of metastasis-associated cell surface glycoproteins and mRNA in a murine large cell lymphoma

A metastatic variant cell subline of the Abelson virus-transformed murine large lymphoma/lymphosarcoma RAW117 has been selected in vivo ten times for liver colonization. Highly metastatic subline RAW117-H10 forms greater than 200 times as many gross surface liver tumor nodules as the parental line RAW117-P. Analysis of cellular proteins and glycoproteins indicates reduced expression of murine Moloney leukemia virus-associated p15, p30, and gp70, and increased expression of a sialoglycoprotein, gp150, in the highly metastatic H10 cells. Northern analyses of oncogene expression suggested that mRNA of various oncogenes was expressed equally or not expressed in the RAW117 cells of differing metastatic potential. Differential gene expression was examined using a cDNA library of 17,600 clones established from poly A+ mRNA isolated from H10 cells. The cDNA library was screened by the colony hybridization technique using probes made from both RAW117-P and -H10 cells. Approximately 99.5% of these cDNA clones were expressed identically in P and H10 cells. Of the few differentially expressed cDNA clones (approx. 150/17,600), one-half of these were identified as Moloney leukemia virus sequences in a separate probing with a radiolabeled Moloney leukemia virus probe. The remainder of the differentially expressed mRNA detected by colony hybridization of the cDNA library were expressed at higher levels (approx. 1/6) or lower levels (approx. 1/3) in the highly metastatic H10 cells.     

Gene expression and tumor cell escape from host effector mechanisms in murine large cell lymphoma

Using in vivo selection methods, we obtained metastatic sublines of the murine RAW117 large cell lymphoma that form multiple liver metastases. The highly metastatic subline RAW117-H10 has a low number of gp70 molecules expressed at the cell surface and low cytostatic sensitivity to activated syngeneic macrophages. This subline was infected with endogenous RNA tumor virus isolated from a high virus-expressing RAW117-P subline of low metastatic potential. After superinfection the H10 subline gradually increased its expression of cell surface gp70 and showed enhanced sensitivity to macrophage-mediated cytostasis, suggesting that gp70 might be involved in host macrophage-mediated surveillance. Culture of RAW117-P and H10 cells in media conditioned by activated macrophages indicated that parental cells are severely growth inhibited in a dose dependent fashion while H10 cells showed almost no effect. Examination of differentially expressed genes in the highly metastatic RAW117-H10 cells by analysis of RNA blots indicated that a mitochondrial gene was expressed at a level that was approximately 10 times higher in H10 cells than in parental cells. This gene was identified as ND5, which codes for a subunit of NADH dehydrogenase (complex I of the mitochondrial electron transport chain); this complex is the target for an activated macrophage-released cytostatic factor. Among other possibilities, the results are consistent with the suggestion that highly metastatic RAW117 cells may escape macrophage surveillance by decreasing the synthesis of specific cell-surface receptors for cytostatic molecules and increasing the synthesis of specific cellular targets for such molecules.     

The control of IgM expression in a murine B cell lymphoma

The regulation of IgM expression was studied in clones derived from a murine B lymphocyte cell line, WEHI279.1. During normal B cell development IgM heavy chain synthesis increases concomitantly with heightened IgM secretion and reduced cell-surface IgM. However, in these subclones, the levels of membrane-bound and secreted IgM were regulated independently of one another. The amount of IgM secreted by the cells was tightly coupled to the amount of heavy chain synthesis, suggesting that the major control of secretion is pretranslational. Surface IgM exhibited a more complex regulation, with both pre- and posttranslational components. Variation in the expression of both forms of IgM occurred at high frequency. Although IgM expression follows a unidirectional pathway in nontransformed cells, the variability in these tumor cells was reversible and cellautonomous. High levels of phenotypic variability may be important in the ability of transformed cells to escape the immune response.     

Stimulation of endothelial cell migration in culture by ladsin,a laminin-5-like cell adhesion protein

Summary Ladsin is a laminin-like cell-adhesive scatter factor with potent cell motility-stimulating ability and was purified from serum-free conditioned medium of a malignant human gastric adenocarcinoma cell line STKM-1. To test its possible role in tumor angiogenesis, we investigated its effect on primary culture of endothelial cells (human umbilical vein endothelial cells) and endothelial cell line ECV304 in this study. Cell adhesion and motility effects of ladsin were observed in both types of endothelial cells. In cell-attachment assay, ladsin interacted with integrin α3β1 that was expressed on the endothelial cell surface. In Boyden chambers, ladsin stimulated both directed and random migration of ECV304 cells. Ladsin induced repair of artificial wounds generated in ECV304 cell monolayers by stimulating cell migration. Ladsin did not affect the growth rate of ECV304 cells at a low cell density but significantly increased the saturation cell density. These results suggest that ladsin may be involved in the adhesion and migration of endothelial cells under some physiological and pathological conditions.     

Porphyromonas gingivalis fimbriae induce adhesion of monocytic cell line U937 to endothelial cells

This study used the human monocytic cell line U937 to examine whether or not Porphyromonas gingivalis fimbriae could induce the adhesion of monocytes to endothelial cells. An in vitro adhesion assay was used to investigate the effects of the fimbriae on U937 cell adhesion to human umbilical vein endothelial cells (HUVEC). The fimbriae enhanced U937 cell adhesion to HUVEC in a dose-dependent manner. U937 cells adhered better to HUVEC pretreated with the fimbriae for a minimum of 2 hr than to untreated HUVEC. The enhanced adhesion was inhibited by a monoclonal antibody against P. gingivalis 381 fimbriae. Pretreatment of U937 cells with the fimbriae for 24 hr enhanced U937 cell adhesion to HUVEC approximately 4-fold. This phenomenon was inhibited by an anti-CD11b antibody, suggesting the involvement of CD11b. These results indicate that P. gingivalis fimbriae can induce monocyte adhesion to the endothelial cell surface. They also suggest that the fimbriae may be involved in the initial event for infiltration of monocytes into the periodontal tissues of individuals with adult periodontitis.     

Cell surface alpha 2,6 sialylation affects adhesion of breast carcinoma cells

Tumor-associated alterations of cell surface glycosylation play a crucial role in the adhesion and metastasis of carcinoma cells. The aim of this study was to examine the effect of alpha 2,6-sialylation on the adhesion properties of breast carcinoma cells. To this end mammary carcinoma cells, MDA-MB-435, were sense-transfected with sialyltransferase ST6Gal-I cDNA or antisense-transfected with a part of the ST6Gal-I sequence. Sense transfectants showed an enhanced ST6Gal-I mRNA expression and enzyme activity and an increased binding of the lectin Sambucus nigra agglutinin (SNA), specific for alpha 2,6-linked sialic acid. Transfection with ST6Gal-I in the antisense direction resulted in less enzyme activity and SNA reactivity. A sense-transfected clone carrying increased amounts of alpha 2,6-linked sialic acid adhered preferentially to collagen IV and showed reduced cell-cell adhesion and enhanced invasion capacity. In contrast, antisense transfection led to less collagen IV adhesion but enhanced homotypic cell-cell adhesion. In another approach, inhibition of ST6Gal-I enzyme activity by application of soluble antisense-oligodeoxynucleotides was studied. Antisense treatment resulted in reduced ST6 mRNA expression and cell surface 2,6-sialylation and significantly decreased collagen IV adhesion. Our results suggest that cell surface alpha 2,6-sialylation contributes to cell-cell and cell-extracellular matrix adhesion of tumor cells. Inhibition of sialytransferase ST6Gal-I by antisense-oligodeoxynucleotides might be a way to reduce the metastatic capacity of carcinoma cells.     

The role of the cytoskeleton in cellular adhesion molecule expression in tumor necrosis factor-stimulated endothelial cells

Leukocyte infiltration is a hallmark of the atherosclerotic lesion. These cells are captured by cellular adhesion molecules (CAMs), including vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), platelet-endothelial cell adhesion molecule (PECAM), and E-selectin, on endothelial cells (EC). We examined the role of the actin cytoskeleton in tumor necrosis factor-alpha (TNF-alpha)-induced translocation of CAMs to the cell surface. Human aortic EC were grown on 96-well plates and an ELISA was used to assess surface expression of the CAMs. TNF-alpha increased VCAM-1, ICAM-1, and E-selectin by 4 h but had no affect on the expression of PECAM. A functioning actin cytoskeleton was important for VCAM-1 and ICAM-1 expression as both cytochalasin D, an actin filament disruptor, and jasplakinolide, an actin filament stabilizer, attenuated the expression of these CAMs. These compounds were ineffective in altering E-selectin surface expression. Myosin light chains are phosphorylated in response to TNF-alpha and this appears to be regulated by Rho kinase instead of myosin light chain kinase. However, the Rho kinase inhibitor, Y27632, had no affect on TNF-alpha-induced CAM expression. ML-7, a myosin light chain kinase inhibitor, had a modest inhibitory effect on the translocation of VCAM-1 but not on ICAM-1 or E-selectin. These data suggest that the surface expression of VCAM-1 and ICAM-1 is dependent on cycling of the actin cytoskeleton. Nevertheless, modulation of actin filaments via myosin light chain phosphorylation is not necessary. The regulation of E-selectin surface expression differs from that of the other CAMs.     

A truncated recombinant intercellular adhesion molecule-1 inhibits adhesion of leukemic cell lines to upregulated endothelial cells

Summary Intercellular adhesion molecule-1, a member of the immunoglobulin supergene family, is the ligand for the integrin lymphocyte function associated antigen-1. Intercellular adhesion molecule-1 and lymphocyte function associated antigen-1 binding interactions mediate leukocyte adherence and migration. Previous work has shown that the adherence of lymphocyte function associated antigen-1 is directed to the first immunoglobulinlike domain of the endothelial cell surface protein intracellular adhesion molecule-1. We have constructed a truncated intercellular adhesion molecule-1 gene encoding the first 185 amino acids from the amino terminus and overexpressed it inEscherichia coli. The recombinant protein was purified from insoluble inclusion bodies and refolded into an active conformation by a denaturation/renaturation cycle. The identity of the protein was confirmed by microsequencing and by Western blot analysis using a polyclonal antibody to ICAM-1. We have demonstrated that this soluble region of the otherwise membrane-bound ligand is an inhibitor of Molt or HL-60 cell adhesion to cytokine-stimulated endothelial cells.     

Characterization of cell signaling,morphology, and differentiation potential of human mesenchymal stem cells based on cell adhesion mechanism

It is essential to characterize the cellular properties of mesenchymal stem cell populations to maintain quality specifications and control in regenerative medicine. Biofunctional materials have been designed as artificial matrices for the stimulation of cell adhesion and specific cellular functions. We have developed recombinant maltose-binding protein (MBP)-fused proteins as artificial adhesion matrices to control human mesenchymal stem cell (hMSC) fate by using an integrin-independent heparin sulfate proteoglycans-mediated cell adhesion. In this study, we characterize cell adhesion-dependent cellular behaviors of human adipose-derived stem cells (hASCs) and human bone marrow stem cells (hBMSCs). We used an MBP-fused basic fibroblast growth factor (MF)-coated surface and fibronectin (FN)-coated surface to restrict and support, respectively, integrin-mediated adhesion. The cells adhered to MF exhibited restricted actin cytoskeleton organization and focal adhesion kinase phosphorylation. The hASCs and hBMSCs exhibited different cytoplasmic projection morphologies on MF. Both hASCs and hBMSCs differentiated more dominantly into osteogenic cells on FN than on MF. In contrast, hASCs differentiated more dominantly into adipogenic cells on MF than on FN, whereas hBMSCs differentiated predominantly into adipogenic cells on FN. The results indicate that hASCs exhibit a competitive differentiation potential (osteogenesis vs. adipogenesis) that depends on the cell adhesion matrix, whereas hBMSCs exhibit both adipogenesis and osteogenesis in integrin-mediated adhesion and thus hBMSCs have noncompetitive differentiation potential. We suggest that comparing differentiation behaviors of hMSCs with the diversity of cell adhesion is an important way to characterize hMSCs for regenerative medicine.     

Adhesion of sea-urchin embryonic cells to substrata coated with cell adhesion molecules

Summary— A cell-to-substratum adhesion assay is developed to study the adhesion of sea-urchin embryonic cells to coated substrata. The involvement in this process of both carbohydrate and protein molecules is reported. Concanavalin A (Con A) increases the attachment of cells to the substratum in a dose-dependent manner and this effect is completely abolished when the incubation is carried out in the presence of the specific monocarbohydrate Con A-inhibitor, α-methyl-d -mannoside. A Con A-mediated enhancement of cell-to-substratum adhesion was also detected on cells deprived of toposome, a glycoprotein complex responsible for cell-to-cell adhesion. The involvement of other molecules as well as toposome in the process of cell-to-substratum adhesion is also investigated. Results of these in vitro experiments indicate that all the molecules tested contribute to the process of cell-to-substratum adhesion.     

Methyl mercury triggers endothelial leukocyte adhesion and increases expression of cell adhesion molecules and chemokines

Cardiovascular disease is the leading cause of morbidity, mortality, and health care costs in the USA, and around the world. Among the various risk factors of cardiovascular disease, environmental and dietary exposures to methyl mercury, a highly toxic metal traditionally labeled as a neurotoxin, have been epidemiologically linked to human cardiovascular disease development. However, its role in development and promotion of atherosclerosis, an initial step in more immediately life-threatening cardiovascular diseases, remains unclear. This study was conducted to examine the role that methyl mercury plays in the adhesion of monocytes to human microvascular endothelial cells (HMEC-1), and the underlying mechanisms. Methyl mercury treatment significantly induced the adhesion of monocyte to HMEC-1 endothelial cells, a critical step in atherosclerosis, while also upregulating the expression of proinflammatory cytokines interleukin-6, interleukin-8. Further, methyl mercury treatment also upregulated the chemotactic cytokine monocyte chemoattractant protein-1 and intercellular adhesion molecule-1. These molecules are imperative for the firm adhesion of leukocytes to endothelial cells. Additionally, our results further demonstrated that methyl mercury stimulated a significant increase in NF-κB activation. These findings suggest that NF-κB signaling pathway activation by methyl mercury is an important factor in the binding of monocytes to endothelial cells. Finally, by using flow cytometric analysis, methyl mercury treatment caused a significant increase in necrotic cell death only at higher concentrations without initiating apoptosis. This study provides new insights into the molecular actions of methyl mercury that can lead to endothelial dysfunction, inflammation, and subsequent atherosclerotic development.     

CD40/CD40L interaction induces E-selectin dependent leukocyte adhesion to human endothelial cells and inhibits endothelial cell migration

Background

CD40 is a receptor expressed on a wide range of cells such as leukocytes and endothelial cells (EC). As a member of the tumor necrosis factor (TNF) superfamily the activation of CD40 by CD40-ligand (CD40L) plays a crucial role for the development and progression of a variety of inflammatory processes including atherosclerosis. The aim of the present study was to investigate the effect of CD40/CD40L interaction on leukocyte adhesion to the endothelium and on endothelial cell migration.

Methods and results

Human umbilical vein endothelial cells (HUVEC) were stimulated with either stable transfectants of mouse myeloma cells expressing the CD40L or wild type cells (4 h). Subsequently adhesion of leukocytes expressing Sialyl Lewis X, the counterpart for E-selectin (HL60 cells), was measured under shear stress (2–2.6 dyne/cm²) using a flow chamber adhesion assay. Stimulation of CD40 led to a significant increase of E-selectin dependent adhesion of leukocytes to the endothelium. Incubation of cells with either the CD40L blocking antibody TRAP-1 or the E-selectin blocking antibody BBA2 during CD40 stimulation completely abolished adhesion of leukocytes to HUVEC. Similar results were found in human cardiac microvasculature endothelial cells (HCMEC). In contrast stimulation of CD40 had no effect on adhesion of l-selectin expressing NALM6-L cells. Furthermore, CD40/CD40L interaction abrogated VEGF-induced migration of HUVEC compared to non-stimulated controls. In comparison experiments, stimulation of endothelial cells with VEGF led to a significant phosphorylation of ERK1/2, Akt, and eNOS. Stimulation of endothelial CD40 had no effect on VEGF-induced phosphorylation of ERK1/2. However, VEGF-induced activation of Akt and eNOS was reduced to baseline levels when endothelial CD40 was stimulated.

Conclusion

CD40/CD40L interaction induces E-selectin dependent adhesion of leukocytes to human endothelial cells and reduces endothelial cell migration by inhibiting the Akt/eNOS signaling pathway.     

Inhibitive effect of purple sweet potato leaf extract and its components on cell adhesion and inflammatory response in human aortic endothelial cells

This study investigated the effects of purple sweet potato leaf extract (PSPLE) and its components, cyanidin and quercetin, on human aortic endothelial cells (HAECs) during the inflammatory process. HAECs were pretreated with 100 μg/mL PSPLE or 10 μM quercetin, cyanidin or aspirin for 18 h followed by TNF-α (2 ng/mL) for 6 h, and U937 cell adhesion was determined. Adhesion molecule expression and CD40 were evaluated; NFκB p65 protein localization and DNA binding were assessed. PSPLE, aspirin, cyanidin and quercetin significantly inhibited TNF-α-induced monocyte-endothelial cell adhesion (p < 0.05). Cyanidin, quercetin and PSPLE also significantly attenuated VCAM-1, IL-8 and CD40 expression, and quercetin significantly attenuated ICAM-1 and E-selectin expression (p < 0.05). Significant reductions in NFκB expression and DNA binding by aspirin, cyanidin and quercetin were also observed in addition to decreased expression of ERK1, ERK2 and p38 MAPK (p < 0.05). Thus, PSPLE and its components, cyanidin and quercetin, have anti-inflammatory effects through modulation of NFκB and MAPK signaling. Further in vivo studies are necessary to explore the possible therapeutic effects of PSPLE on atherosclerosis.     

Interactions of Schwann cells with neurites and with other Schwann cells involve the calcium-dependent adhesion molecule,N-cadherin

During embryogenesis, Schwann cells interact with axons and other Schwann cells, as they migrate, ensheath axons, and participate in organizing peripheral nervous tissues. The experiments reported here indicate that the calcium-dependent molecule, N-cadherin, mediates adhesion of Schwann cells to neurites and to other Schwann cells. Cell cultures from chick dorsal root ganglia and sciatic nerves were maintained in media containing either 2mM Ca⁺⁺ or 0.2 mM Ca⁺⁺, a concentration that inactivates calcium-dependent cadherins. When the leading lamellae of Schwann cells encountered migrating growth cones in medium with 2 mM Ca⁺⁺, they usually remained extended, and the growth cones often advanced onto the Schwann cell upper surface. In the low Ca⁺⁺ medium, the frequency of withdrawal of the Schwann cell lamella after contact with a growth cone was much greater, and withdrawal was the most common reaction to growth cone contact in medium with 2 mM Ca⁺⁺ and anti-N-cadherin. Similarly, when motile leading margins of two Schwann cells touched in normal Ca⁺⁺ medium, they often formed stable areas of contact. N-cadherin and vinculin were co-concentrated at these contact sites between Schwann cells. However, in low Ca⁺⁺ medium or in the presence of anti-N-cadherin, interacting Schwann cells usually pulled away from each other in a behavior reminiscent of contact inhibition between fibroblasts. In cultures of dissociated cells in normal media, Schwann cells frequently were aligned along neurites, and ultrastructural examination showed extensive close apposition between plasma membranes of neurites and Schwann cells. When dorsal root ganglia explants were cultured with normal Ca⁺⁺, Schwann cells migrated away from the explants in close association with extending neurites. All these interactions were disrupted in media with 0.2 mM Ca⁺⁺. Alignment of Schwann cells along neurites was infrequent, as were extended close apposition between axonal and Schwann cell plasma membranes. Finally, migration of Schwann cells from ganglionic explants was reduced by disruption of adhesive contact with neurites. The addition of antibodies against N-cadherin to medium with normal Ca⁺⁺ levels had similar effects as lowering the Ca⁺⁺ concentration, but antibodies against the neuronal adhesive molecule, L1, had no effects on interactions between Schwann cells and neurites.     

肿瘤条件培养基对人脐静脉内皮细胞增殖、黏附、迁移能力的调节

本文旨在研究肿瘤条件培养基(tumor conditioned medium,TCM)对人脐静脉内皮细胞(human umbilical vein endothelial cell,HUVEC)增殖、黏附和迁移能力的影响.采用MTT法测定TCM作用24 h后内皮细胞的增殖水平,实验设对照组、TCM原液(TCM stoc...     

Progesterone enhances vascular endothelial cell migration via activation of focal adhesion kinase

The mechanisms of progesterone on endothelial cell motility are poorly investigated. Previously we showed that progesterone stimulated endothelial cell migration via the activation of actin-binding protein moesin, leading to actin cytoskeleton remodelling and the formation of cell membrane structures required for cell movement. In this study, we investigated the effects of progesterone on the formation of focal adhesion complexes, which provide anchoring sites for cell movement. In cultured human umbilical endothelial cells, progesterone enhanced focal adhesion kinase (FAK) phosphorylation at Tyr(397) in a dose- and time-dependent manner. Several signalling inhibitors interfered with progesterone-induced FAK activation, including progesterone receptor (PR) antagonist ORG 31710, specific c-Src kinase inhibitor PP2, phosphatidylinosital-3 kinase (PI3K) inhibitor wortmannin as well as ρ-associated kinase (ROCK-2) inhibitor Y27632. It suggested that PR, c-Src, PI3K and ROCK-2 are implicated in this action. In line with this, we found that progesterone rapidly promoted c-Src/PI3K/Akt activity, which activated the small GTPase RhoA/ρ-associated kinase (ROCK-2) complex, resulting in FAK phosphorylation. In the presence of progesterone, endothelial cells displayed enhanced horizontal migration, which was reversed by small interfering RNAs abrogating FAK expression. In conclusion, progesterone promotes endothelial cell movement via the rapid regulation of FAK. These findings provide new information on the biological actions of progesterone on human endothelial cells that are relevant for vascular function.     

Effect of lectin from the ascidian on the growth and the adhesion of HeLa cells

Cell adhesion molecules, some of which are lectins, play a key role in the control of normal and pathological processes of various living organisms. We found herein that NacetylDglucosaminespecific lectin, isolated from the ascidian Didemnum ternatanum (DTL), alters the growth properties of HeLa tumor cells depending on the anchorage. DTL was shown to increase the proliferation of HeLa cells grown in soft agar greatly (in anchorageindependent fashion). In contrast, DTL inhibits the proliferative activity of HeLa cells grown on solid substrate and acts as inductor of differentiation, slowing cell growth, increasing the cell attachment and spreading. Scanning electron microscopic data have demonstrated that DTL treatment resulted in pronounced changes of the shape and surface of HeLa cells. Changes of cellular morphology correlated with essential redistribution of actin microfilaments.