Regulation of trophoblast beta1-integrin expression by contact with endothelial cells

Background  

In human and non-human primates, migratory trophoblasts penetrate the uterine epithelium, invade uterine matrix, and enter the uterine vasculature. Invasive trophoblasts show increased expression of β1 integrin. Since trophoblast migration within the uterine vasculature involves trophoblast attachment to endothelial cells lining the vessel walls, this raises the possibility that cell-cell contact and/or factors released by endothelial cells could regulate trophoblast integrin expression. To test this, we used an in vitro system consisting of early gestation macaque trophoblasts co-cultured on top of uterine microvascular endothelial cells.     

The chemokines, CX3CL1, CCL14, and CCL4, promote human trophoblast migration at the feto-maternal interface

Human embryo implantation is a complex process involving blastocyst attachment to the endometrial epithelium and subsequent trophoblast invasion of the decidua. Chemokines, critical regulators of leukocyte migration, are abundant in endometrial epithelial and decidual cells at this time. We hypothesized that endometrial chemokines stimulate trophoblast invasion. Chemokine receptors CX3CR1 and CCR1 were immunolocalized in human first-trimester implantation sites, specifically to endovascular extravillous trophoblasts, but not to the invading interstitial EVTs (iEVTs), with weak staining also on syncytium. CCR3 was localized to invading iEVTs and to microvilli on the syncytial surface. Expression of CX3CL1 (fractalkine), CCL7 (MCP-3), and their receptors (CX3CR1, CCR1, CCR2, CCR3, and CCR5) mRNA was examined in cellular components of the maternal-embryonic interface by RT-PCR. Both chemokines were abundant in entire endometrium and placenta, endometrial cells (primary cultures and HES, a human endometrial epithelial cell line) and trophoblast cell lines (JEG-3, ACIM-88, and ACIM-32). Chemokine receptor mRNA was expressed by placenta and trophoblast cell lines: CCR1 by all trophoblast cell types, whereas CCR2, CCR3, and CX3CR1 were more variable. CX3CR1, CCR1, CCR2, and CCR5 were also expressed by endometrial cells. Migration assays used the trophoblast cell line most closely resembling extravillous cytotrophoblast (AC1M-88). Trophoblast migration occurred in response to CX3CL1, CCL14, and CCL4, but not CCL7. Endometrial cell-conditioned media also stimulated trophoblast migration; this was attenuated by neutralizing antibodies to CX3CL1 and CCL4. Thus, chemokines are expressed by maternal and embryonic cells during implantation, whereas corresponding receptors are on trophoblast cells. Promotion of trophoblast migration by chemokines and endometrial cell conditioned medium indicates an important involvement of chemokines in maternal-fetal communication.     

MUC1 is involved in trophoblast transendothelial migration

The factors that regulate trophoblast invasion of the uterine vasculature are incompletely understood. In this paper we show that macaque trophoblasts express the mucin, MUC1, and that it is involved in trophoblast-endothelial interaction. Immunocytochemistry, Western blotting and RT-PCR analyses confirmed that MUC1 was expressed by isolated early gestation macaque trophoblasts. MUC1 was also detected in endovascular trophoblasts in sections of placental-decidual tissue during early gestation. A blocking antibody against MUC1 reduced trophoblast adhesion to uterine endothelial cells and also blocked trophoblast transendothelial migration. MUC1 is known to bind to Intercellular Adhesion Molecule-1 (ICAM-1) in other systems. Incubation in the presence of a blocking antibody against Intercellular Adhesion Molecule-1 (ICAM-1) or recombinant ICAM-1 modestly, but significantly, reduced transendothelial trophoblast migration. These results are consistent with the idea that MUC1 is involved in trophoblast adhesion to uterine endothelial cells and in trophoblast transendothelial migration.     

Effect of shear stress on migration and integrin expression in macaque trophoblast cells

During fetal development, trophoblast cells enter endometrial capillaries, migrate within the uterine vasculature, and eventually reside within spiral arteries of the uterus. This invasive activity is accompanied by upregulation of trophoblast beta1 integrin expression. Fluid mechanical shear stress regulates migration and expression of adhesion molecules in vascular endothelial cells, but nothing is known about the effects of shear stress on trophoblast cells. We tested the hypothesis that shear stress regulates the motility and beta1 integrin expression of trophoblast cells. Early gestation macaque trophoblast cells were cultured in 1 x 1-mm square cross-section capillary tubes within which the flow field was determined using three-dimensional computational fluid dynamic simulations. Trophoblast cells in the capillary tubes were exposed to a steady shear stress of 7.5, 15, or 30 dyn/cm2 for up to 24 h. In the absence of flow, trophoblast cells were highly dynamic with constant nondirectional positional shifts but with no net cell migration. Exposure of the cells to shear stress within 24-72 h of cell plating significantly increased the level of this activity and led to net cell migration in the direction of flow. Shear stress also increased the expression and altered the topography of beta1 integrin. These results suggest that shear stress regulates trophoblast motility and beta1 integrin expression in vitro.     

Regulation of blastocyst migration,apposition, and initial adhesion by a chemokine,interferon gamma-inducible protein 10 kDa (IP-10), during early gestation

For a pregnancy to be established, initial apposition and adhesion of the blastocyst to maternal endometrium must occur in a coordinated manner; however, a key factor(s) that mediates the trophoblast cell migration and attachment to the apical surface of the endometrium has not been identified. In this study, we examined the effect of an endometrial chemokine, interferon-gamma-inducible protein 10 kDa (IP-10), on conceptus migration to the endometrial epithelium. We first studied endometrial IP-10 mRNA expression, which was localized in the subepithelial stromal region, and detected the protein in the uterine flushing media during early pregnancy. Expression of IP-10 mRNA by the endometrium of cyclic animals was stimulated by the addition of a conceptus factor interferon-tau (IFN-tau). Immunofluorescent analysis revealed that IP-10 receptor, CXCR3, was localized in the trophoblast cells, to which biotinylated-recombinant caprine IP-10 (rcIP-10) bound. Chemotaxis assay indicated that rcIP-10 stimulated the migration of trophoblast cells, and the effects of rcIP-10 were neutralized by the pretreatment with an anti-IP-10 antibody. Adhesive activity of trophoblast cells to fibronectin was promoted by rcIP-10, and the effect was inhibited by the use of anti-IP-10 antibody. Further adhesion experiments demonstrated that binding of trophoblast cells to fibronectin was completely inhibited by a peptide of the Arg-Gly-Asp (RGD) sequence, which binds to integrins alpha5beta1, alphaVbeta1, alphaVbeta3, and alphaVbeta5, whereas non-binding peptide containing Arg-Gly-Glu (RGE) had minimal effects. More importantly, rcIP-10 promoted the adhesion of trophoblast cells to primary cells isolated from endometrial epithelium. Furthermore, rcIP-10 stimulated the expression of integrin alpha5, alphaV, and beta3 subunit mRNA in trophoblast cells. These findings suggest that endometrial IP-10 regulates the establishment of apical interactions between trophoblast and epithelial cells during early gestation.     

Trophoblast migration under flow is regulated by endothelial cells

During pregnancy, trophoblasts enter the uterine vasculature and are found in spiral arteries far upstream of uterine capillaries. It is unknown whether trophoblasts reach the spiral arteries by migration within blood vessels against blood flow or by intravasation directly into spiral arteries after interstitial migration. We have developed an in vitro system consisting of early gestation macaque monkey trophoblasts cocultured with uterine endothelial cells and have exposed the cells in a parallel plate flow chamber to physiological levels of shear stress. Videomicroscopy followed by quantitative image analysis revealed that the migratory activity (expressed as average displacement and average migration velocity) of trophoblasts cultured on top of endothelial cells remained unchanged between shear stresses of 1-30 dyne/cm(2) whereas activity of trophoblasts alone increased with increasing shear stress. When the direction of migration was assessed at 1 and 7.5 dyne/cm(2), the extent of migration against and with flow was roughly equal for both trophoblasts alone and cocultured trophoblasts. At shear stress levels of 15 and 30 dyne/cm(2), trophoblasts incubated alone showed a significant decrease in migration against flow and corresponding increased migration in the direction of flow. In contrast, trophoblasts cocultured with uterine endothelial cells maintained the same extent of migration against flow at all shear stress levels. Migration against flow was also maintained when trophoblasts were cultured with endothelial cell-conditioned medium or fixed endothelial cells. The results indicate that factors expressed on the surface of uterine endothelial cells and factors released by endothelial regulate trophoblast migration under flow.     

Dynamic alterations in integrin α4 expression by hypoxia are involved in trophoblast invasion during early implantation

Implantation of the blastocyst into the maternal endometrium is mediated by a population of well-differentiated primary cells of the placenta known as trophoblasts, which grow in an invasive and destructive fashion similar to tumor cells. Interactions between the endometrium and trophoblasts are regulated by a coordinated interplay of extracellular matrix (ECM) proteins secreted by the invading extravillous trophoblasts. Integrins act as adhesion receptors and mediate both cell-ECM and cell-cell interactions. However, the correlation between integrin expression and trophoblast invasion under hypoxia is unclear. Here, we analyzed the expression of integrins in HTR-8/SVneo trophoblast cells exposed to hypoxic conditions in order to demonstrate an association between invasion activity and integrin expression in trophoblasts. Trophoblasts were examined by microarray analysis, RT-PCR, western blotting, and zymography after 1% hypoxic treatment, and cell invasion was estimated. The dynamic expression of integrins and human matrix metalloproteinases (MMPs) was observed under hypoxic conditions. The invasiveness of trophoblasts cultured under 1% hypoxic conditions was significantly greater than that of trophoblasts cultured under normoxic conditions through alterations in MMP-2 and -9 (P < 0.05). Notably, integrin α4 expression during early hypoxia was negatively regulated by hypoxia-inducible factor-1alpha (HIF-1alpha) expression in trophoblasts. The downregulation of integrin α4 expression by siRNA treatment controlled trophoblast invasion activity (P < 0.05). Taken together, we suggest that dynamic changes in integrins, including those in integrin α4 expression by hypoxia, play a regulatory role in trophoblast invasion. These findings expand our understanding of the potential roles of integrin α4 in implantation.     

Placental villous mesenchymal cells trigger trophoblast invasion

The successful transformation of uterine spiral arteries by invasion trophoblasts is critical for the formation of the human hemochorial placenta. Placental trophoblast migration and invasion are well regulated by various autocrine/paracrine factors at maternal–fetal interface. Human placental multipotent mesenchymal stromal cells (hPMSCs) are a subpopulation of villous mesenchymal cells and have been shown to produce a wide array of soluble cytokines and growth factors including HGF (hepatocyte growth factor). The function of hPMSCs in placental villous microenvironment has not been explored. The interaction between hPMSCs and trophoblasts was proposed in vitro in a recent article. HGF produced by hPMSCs was able to engage c-Met receptor on trophoblast and induced the trophoblast cAMP expression. The cAMP activated PKA, which in turn, signaled to Rap1 and led to integrin β1 activation. The total integrin β1 protein expression by trophoblasts was not affected by HGF stimulation. Hypoxia downregulated HGF expression by hPMSCs. HGF and PKA activator 6-Bnz-cAMP increased trophoblast adhesion and migration that were inhibited by PKA inhibitor H89 or Rap1 siRNA. Thus, hPMSCs-derived paracrine HGF can regulate trophoblast migration during placentation. These findings provided insight revealing at least one mechanism by which hPMSCs implicated in the development of preeclampsia.     

Placental villous mesenchymal cells trigger trophoblast invasion

The successful transformation of uterine spiral arteries by invasion trophoblasts is critical for the formation of the human hemochorial placenta. Placental trophoblast migration and invasion are well regulated by various autocrine/paracrine factors at maternal–fetal interface. Human placental multipotent mesenchymal stromal cells (hPMSCs) are a subpopulation of villous mesenchymal cells and have been shown to produce a wide array of soluble cytokines and growth factors including HGF (hepatocyte growth factor). The function of hPMSCs in placental villous microenvironment has not been explored. The interaction between hPMSCs and trophoblasts was proposed in vitro in a recent article. HGF produced by hPMSCs was able to engage c-Met receptor on trophoblast and induced the trophoblast cAMP expression. The cAMP activated PKA, which in turn, signaled to Rap1 and led to integrin β1 activation. The total integrin β1 protein expression by trophoblasts was not affected by HGF stimulation. Hypoxia downregulated HGF expression by hPMSCs. HGF and PKA activator 6-Bnz-cAMP increased trophoblast adhesion and migration that were inhibited by PKA inhibitor H89 or Rap1 siRNA. Thus, hPMSCs-derived paracrine HGF can regulate trophoblast migration during placentation. These findings provided insight revealing at least one mechanism by which hPMSCs implicated in the development of preeclampsia.     

Temporal and spatial expression of integrins and their extracellular matrix ligands at the maternal-fetal interface in the rhesus monkey during pregnancy

The integrin and extracellular matrix protein (ECM)-mediated adhesion and invasion of the receptive maternal uterine endometrium by trophoblasts is a critical event in the complex physiological process of pregnancy. Although the process has been largely characterized in mice, the relevant mechanism in primates remains unclear. We investigated the expression patterns and dynamic alterations of integrin subunits (alpha1, alpha5, alpha6, beta1, and beta4) and their ECM ligands, such as laminin (LN), type IV collagen (Col IV), and fibronectin (FN), at the maternal-fetal interface during Gestational Days 15, 25, 50, and 100 and at full term in 20 pregnant rhesus monkeys. Immunohistochemistry and in situ hybridization revealed that a relatively high expression of integrins occurred in trophoblast cells at Gestational Day 15, with the peak level occurring at Day 25. The expression level decreased from Day 50 to term. Along the invasive pathway, expression levels of integrin alpha1, alpha5, and beta1 subunits were gradually elevated from the proximal to distal column, reaching peak level in the trophoblast shell, but were reduced in those invasive extravillous cytotrophoblast (EVCT) cells in contact with the decidua. Integrin alpha1, alpha5, beta1, and beta4 subunits were also highly expressed in decidual stromal cells and moderately expressed in the maternal epithelium and endothelium. Immunoreactive FN, LN, and Col IV were distributed in EVCT and decidual stromal cells and part of the uterine epithelial and endothelial cells. These data suggest that the correlated expression of integrins and their ECM ligands at the maternal-fetal interface might be involved in regulation of cell proliferation and differentiation and the counterbalanced invasion-accelerating and invasion-restraining processes in trophoblast cells during the early stage of pregnancy.     

Alpha5beta1, alphaVbeta3 and the platelet-associated integrin alphaIIbbeta3 coordinately regulate adhesion and migration of differentiating mouse trophoblast cells

During blastocyst implantation, interaction between integrins on the apical surface of the trophoblast and extracellular matrix (ECM) in the endometrium anchors the embryo to the uterine wall. Strong adhesion of the blastocyst to fibronectin (FN) requires integrin signaling initiated by exogenous fibronectin. However, it is not known how integrin signaling enhances blastocyst adhesion. We present new evidence that the integrin, alphaIIbbeta3, plays a key role in trophoblast adhesion to fibronectin during mouse peri-implantation development. Trafficking of alphaIIb to the apical surface of the trophoblast increased dramatically after blastocysts were exposed to fibronectin, whereas other fibronectin-binding integrins, alpha5beta1 and alphaVbeta3, were resident at the apical surface before ligand exposure. Functional comparisons among the three integrins revealed that ligation of alpha5beta1 most efficiently strengthened blastocyst fibronectin-binding activity, while subsequent trophoblast cell migration was dependent primarily on the beta3-class integrins. In vivo, alphaIIb was highly expressed by invasive trophoblast cells in the ectoplacental cone and trophoblast giant cells of the parietal yolk sac. These data demonstrate that trafficking of alphaIIb regulates adhesion between trophoblast cells and fibronectin as invasion of the endometrium commences.     

Differential expression of the metastasis suppressor KAI1 in decidual cells and trophoblast giant cells at the feto-maternal interface

Invasion of trophoblasts into maternal uterine tissue is essential for establishing mature feto-maternal circulation. The trophoblast invasion associated with placentation is similar to tumor invasion. In this study, we investigated the role of KAI1, an anti-metastasis factor, at the maternal-fetal interface during placentation. Mouse embryos were obtained from gestational days 5.5 (E5.5) to E13.5. Immunohistochemical analysis revealed that KAI1 was expressed on decidual cells around the track made when a fertilized ovum invaded the endometrium, at days E5.5 and E7.5, and on trophoblast giant cells, along the central maternal artery of the placenta at E9.5. KAI1 in trophoblast giant cells was increased at E11.5, and then decreased at E13.5. Furthermore, KAI1 was upregulated during the forskolinmediated trophoblastic differentiation of BeWo cells. Collectively, these results indicate that KAI1 is differentially expressed in decidual cells and trophoblasts at the maternal-fetal interface, suggesting that KAI1 prevents trophoblast invasion during placentation. [BMB Reports 2013; 46(10): 507-512]     

Trophoblasts acquire a chemokine receptor, CCR1, as they differentiate towards invasive phenotype

At the human feto-maternal interface, trophoblasts differentiate towards extravillous trophoblasts (EVTs) and form the cell column. EVTs acquire invasive activity in the distal part of the cell column and begin to migrate into the maternal tissue. We previously reported that dipeptidyl peptidase IV (DPPIV) is expressed on EVTs in the proximal part of cell column and is involved in the inhibition of their migration. Because DPPIV has been shown to degrade several chemokines, we examined possible roles of chemokines in EVT migration. Immunohistochemistry demonstrated that C-C chemokine receptor 1 (CCR1) was hardly detected on cytotrophoblasts and syncytiotrophoblast but was expressed on EVTs in the cell column. In vitro, CCR1 protein was also present on the surface of EVTs that grew out from chorionic villous explants cultured under 20% O2. Chemokines that can bind to CCR1 (CCR1 ligands), such as regulated on activation, normal T cell expressed and secreted (RANTES) and macrophage inflammatory protein-1alpha (MIP-1alpha), were confirmed in the decidual tissues by RT-PCR and immunohistochemistry. These CCR1 ligands promoted the migration of the EVTs that were isolated from the explant cultures in vitro. These results indicate that CCR1 is expressed on trophoblasts as they differentiate to EVTs and that CCR1 ligands produced from the decidual tissue induce EVT migration. By contrast, CCR1 was scarcely expressed on EVTs that grew out from villous explants cultured in 1% O2, indicating that a relatively high oxygenic environment is needed to induce CCR1 expression. Moreover, CCR1 expression on the isolated EVTs was significantly reduced in the presence of decidua-conditioned medium. Such regulation of CCR1 by surrounding oxygenic and decidual environments supports a close correlation between EVT invasion and their expression of CCR1. This study demonstrates that trophoblasts acquire CCR1 as they differentiate to an invasive phenotype at the villus-anchoring sites and indicates a novel role for the chemokine-CCR1 system in the initial step of trophoblastic invasion towards the maternal tissue.     

Silencing of Paternally Expressed Gene 10 Inhibits Trophoblast Proliferation and Invasion

Paternally expressed gene 10 (PEG10) is an imprinted and monoallelic expressed gene. Previous study using a knockout mouse model revealed a crucial role of PEG10 in placental development, yet the exact function of PEG10 during placentation remains to be elucidated. In this study, denuded chorionic villi were prepared from first trimester human placentas, and transduced with PEG10 small interference RNA (siRNA) or non-targeting control sequence by lentiviral infection. Immunohistochemical staining revealed that silencing of PEG10 in the chorionic villous explants resulted in reduced immune-reactivity to CK7, Ki67 and integrin α5, implying that silencing of PEG10 impaired the proliferation of villous trophoblasts and may interfere with the activity of extravillous trophoblasts. We further investigated the role of PEG10 in the proliferation, migration and invasion of JEG-3 trophoblast cell line and the primary chorionic villous cells. PEG10-silenced JEG-3 cells and primary chorionic villous cells displayed a reduced proliferation rate and impaired invasiveness in vitro. Silencing of PEG10 in trophoblast cells led to upregulated expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) as well as downregulated expression of matrix metalloproteinase (MMP)-2 and MMP-9. Furthermore, knockdown of TIMP-1 reversed the suppressed invasiveness of PEG10 siRNA-transduced JEG-3 cells. In conclusion, our study demonstrates that PEG10 plays an important role in trophoblast proliferation and promotes trophoblast invasion through TIMP-1.     

Expression of SWAP-70 in the uterus and feto-maternal interface during embryonic implantation and pregnancy in the rhesus monkey (Macaca mulatta)

SWAP-70 is a unique signaling protein involved in multiple processes including lymphatic cell activation, migration, adhesion, and cytoskeleton organization. Its role in reproductive system remains to be unclear. In the present study, the spatial and temporal expression of SWAP-70 in the uterus during normal menstrual cycle as well as on the feto-maternal interface during pregnancy was investigated in the rhesus monkey by in situ hybridization and immunohistochemistry. It was shown that SWAP-70 was mainly expressed in glandular epithelial cells of uterine endometrium, and the level peaked at the mid-secretory stage. At the beginning of embryonic implantation, SWAP-70 was intensely expressed at the implantation site, mainly localized in glandular and luminal epithelial cells, as well as in primary trophoblasts and epithelial plaque. High level of SWAP-70 was observed in villous cytotrophoblast (VCT), syncytiotrophoblast (ST), column cytotrophoblast, trophoblast shell, interstitial trophoblast, and endovascular trophoblast during gestational days 15–25. From gestational day 50 to term, expression of SWAP-70 decreased evidently and was restricted in VCT cells. What’s more, SWAP-70 co-localized with F-actin on the feto-maternal interface, especially in highly motive extravillous trophoblasts. The data indicate that SWAP-70 may be involved in regulating motility of trophoblast cells during embryonic implantation and placentation.     

sLeX/L-selectin mediates adhesion in vitro implantation model

The complex implantation process is initiated by the recognition and adhesion between the embryo and uterine endometrial epithelium. The expression and interactions between the adhesive molecules from both fetal and maternal sides are crucial for the successful implantation. In this study, we aimed to investigate the expression and adhesive function of sLeX on the trophoblasts and L-selectin on uterine epithelial cells mediated the adhesion at the fetal-maternal interface, and to further explore whether this adhesion system could induce endometrial apoptosis, using in vitro implantation model consisting of the human trophoblast cell line (JAR) and human uterine epithelial cell line (RL95-2). The results showed that sLeX was expressed on JAR cells by indirect immunofluorescence staining. After transfection of JAR cells with fucosyltransferase VII (FUT7) which is the key enzyme for sLeX synthesis, the expression of FUT7 and sLeX synthesis were increased, and the percent adhesion of trophoblast cells to RL95-2 cell monolayer was significantly increased (P?相似文献   

Implantation-associated changes in bovine uterine expression of integrins and extracellular matrix

Appropriate integrin expression appears to be necessary for successful implantation of human embryos and varies considerably among species. The present study was undertaken to determine the distributions of integrin subunits alpha(1), alpha(3), and alpha(6) as well as the extracellular matrix (ECM) components collagen IV and laminin in implanting bovine trophoblast and endometrium. Immunohistochemical staining of cryostat sections prepared from nonpregnant endometrium, of preattachment through to early villus development pregnant endometrium (Days 18, 21, 24, and 30), and of isolated trophoblast binucleate cells was performed. Trophoblast down-regulated the integrin alpha(1) subunit as attachment proceeded, whereas reactivity scores for alpha(6) antibody tended to increase from Day 18 through 24 and remained high. A subpopulation of trophoblast binucleate cells expressed the alpha(3) integrin subunit. Uterine epithelium constitutively expressed alpha(3) and alpha(6) integrin subunits, but the alpha(1) subunit was down-regulated as the luminal epithelium was modified. Collagen IV and laminin reactivity increased in the basal lamina and underlying subepithelial stroma as pregnancy proceeded. The results suggest that binucleate cell fusion with the maternal epithelium initiates integrin and ECM changes in the subepithelial stroma.     

CCL5 and CCR5 interaction promotes cell motility in human osteosarcoma

Background

Osteosarcoma is characterized by a high malignant and metastatic potential. CCL5 (previously called RANTES) was originally recognized as a product of activated T cells, and plays a crucial role in the migration and metastasis of human cancer cells. It has been reported that the effect of CCL5 is mediated via CCR receptors. However, the effect of CCL5 on migration activity and integrin expression in human osteosarcoma cells is mostly unknown.

Methodology/Principal Findings

Here we found that CCL5 increased the migration and expression of αvβ3 integrin in human osteosarcoma cells. Stimulation of cells with CCL5 increased CCR5 but not CCR1 and CCR3 expression. CCR5 mAb, inhibitor, and siRNA reduced the CCL5-enhanced the migration and integrin up-regulation of osteosarcoma cells. Activations of MEK, ERK, and NF-κB pathways after CCL5 treatment were demonstrated, and CCL5-induced expression of integrin and migration activity was inhibited by the specific inhibitor and mutant of MEK, ERK, and NF-κB cascades. In addition, over-expression of CCL5 shRNA inhibited the migratory ability and integrin expression in osteosarcoma cells.

Conclusions/Significance

CCL5 and CCR5 interaction acts through MEK, ERK, which in turn activates NF-κB, resulting in the activations of αvβ3 integrin and contributing the migration of human osteosarcoma cells.