Neuropilin-1-mediated vascular permeability factor/vascular endothelial growth factor-dependent endothelial cell migration

Neuropilin-1 (NRP-1) has been found to be expressed by endothelial cells and tumor cells as an isoform-specific receptor for vascular permeability factor/vascular endothelial growth factor (VEGF). Previous studies were mainly focused on the extracellular domain of NRP-1 that can bind to VEGF165 and, thus, enables NRP-1 to act as a co-receptor for VEGF165, which enhances its binding to VEGFR-2 and its bioactivity. However, the exact functional roles and related signaling mechanisms of NRP-1 in angiogenesis are not well understood. In this study we constructed a chimeric receptor, EGNP-1, by fusing the extracellular domain of epidermal growth factor receptor to the transmembrane and intracellular domains of NRP-1 and transduced it into HUVECs with a retroviral expression vector. We observed that NRP-1/EGNP-1 mediates ligand-stimulated migration of human umbilical vein endothelial cells (HUVECs) but not proliferation. Our results show that NRP-1 alone can mediate HUVEC migration through its intracellular domain, and its C-terminal three amino acids (SEA-COOH) are essential for the process. We demonstrate that phosphatidylinositol 3-kinase inhibitor Ly294002 and the p85 dominant negative mutant can block NRP-1-mediated HUVEC migration. NRP-1-mediated migration can be significantly reduced by overexpression of the dominant negative mutant of RhoA (RhoA-19N). In addition, Gq family proteins and Gbetagamma subunits are also required for NRP-1-mediated HUVEC migration. These results show for the first time that NRP-1 can independently promote cell signaling in endothelial cells and also demonstrate the importance of last three amino acids of NRP-1 for its function.     

Hic-5 promotes endothelial cell migration to lysophosphatidic acid

Endothelial cell migration is critical for proper blood vessel development. Signals from growth factors and matrix proteins are integrated through focal adhesion proteins to alter cell migration. Hydrogen peroxide-inducible clone 5 (Hic-5), a paxillin family member, is enriched in the focal adhesions in bovine pulmonary artery endothelial (BPAE) cells, which migrate to lysophosphatidic acid (LPA) on denatured collagen. In this study, we investigate the role of Hic-5 in LPA-stimulated endothelial cell migration. LPA recruits Hic-5 to the focal adhesions and to the pseudopodia in BPAE cells plated on collagen, suggesting that recruitment of Hic-5 to focal adhesions is associated with endothelial cell migration. Knockdown of endogenous Hic-5 significantly decreases migration toward LPA, confirming involvement of Hic-5 in migration. To address the role of Hic-5 in endothelial cell migration, we exogenously expressed wild-type (WT) Hic-5 and green fluorescent protein Hic-5 C369A/C372A (LIM3 mutant) constructs in BPAE cells. WT Hic-5 expression increases chemotaxis of BPAE cells to LPA, whereas migration toward LPA of the green fluorescent protein Hic-5 C369A/C372A-expressing cells is similar to that shown in vector control cells. Additionally, ERK phosphorylation is enhanced in the presence of LPA in WT Hic-5 cells. A pharmacological inhibitor of MEK activity inhibits LPA-stimulated WT Hic-5 cell migration and ERK phosphorylation, suggesting Hic-5 enhances migration via MEK activation of ERK. Together, these studies indicate that Hic-5, a focal adhesion protein in endothelial cells, is recruited to the pseudopodia in the presence of LPA and enhances migration.     

Glycosyltransferase Extl1 promotes CCR7-mediated dendritic cell migration to restrain infection and autoimmunity

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P-cadherin promotes collective cell migration via a Cdc42-mediated increase in mechanical forces

Collective cell migration (CCM) is essential for organism development, wound healing, and metastatic transition, the primary cause of cancer-related death, and it involves cell–cell adhesion molecules of the cadherin family. Increased P-cadherin expression levels are correlated with tumor aggressiveness in carcinoma and aggressive sarcoma; however, how P-cadherin promotes tumor malignancy remains unknown. Here, using integrated cell biology and biophysical approaches, we determined that P-cadherin specifically induces polarization and CCM through an increase in the strength and anisotropy of mechanical forces. We show that this mechanical regulation is mediated by the P-cadherin/β-PIX/Cdc42 axis; P-cadherin specifically activates Cdc42 through β-PIX, which is specifically recruited at cell–cell contacts upon CCM. This mechanism of cell polarization and migration is absent in cells expressing E- or R-cadherin. Thus, we identify a specific role of P-cadherin through β-PIX–mediated Cdc42 activation in the regulation of cell polarity and force anisotropy that drives CCM.     

Inhibition of matrix metalloproteinase 14 (MMP-14)-mediated cancer cell migration

Matrix metalloproteinases (MMPs) have been shown to be key players in both extracellular matrix remodeling and cell migration during cancer metastasis. MMP-14, a membrane-anchored MMP, in particular, is closely associated with these processes. The hemopexin (PEX) domain of MMP-14 has been proposed as the modulating region involved in the molecular cross-talk that initiates cell migration through homodimerization of MMP-14 as well as heterodimerization with the cell surface adhesion molecule CD44. In this study, minimal regions required for function within the PEX domain were investigated through a series of substitution mutations. Blades I and IV were found to be involved in cell migration. We found that blade IV is necessary for MMP-14 homodimerization and that blade I is required for CD44 MMP-14 heterodimerization. Cross-talk between MMP-14 and CD44 results in phosphorylation of EGF receptor and downstream activation of the MAPK and PI3K signaling pathways involved in cell migration. Based on these mutagenesis analyses, peptides mimicking the essential outermost strand motifs within the PEX domain of MMP-14 were designed. These synthetic peptides inhibit MMP-14-enhanced cell migration in a dose-dependent manner but have no effect on the function of other MMPs. Furthermore, these peptides interfere with cancer metastasis without affecting primary tumor growth. Thus, targeting the MMP-14 hemopexin domain represents a novel approach to inhibit MMP-14-mediated cancer dissemination.     

Group IB secretory phospholipase A2 promotes matrix metalloproteinase-2-mediated cell migration via the phosphatidylinositol 3-kinase and Akt pathway

Secretory phospholipase A(2) (sPLA(2)), abundantly expressed in various cells including fibroblasts, is able to promote proliferation and migration. Degradation of collagenous extracellular matrix by matrix metalloproteinase (MMP) plays a role in the pathogenesis of various destructive disorders, such as rheumatoid arthritis, tumor invasion, and metastasis. Here we show that group IB PLA(2) increased pro-MMP-2 activation in NIH3T3 fibroblasts. MMP-2 activity was stimulated by group IB PLA(2) in a dose- and time-dependent manner. Consistent with MMP-2 activation, sPLA(2) decreased expression of type IV collagen. These effects are due to the reduction of tissue inhibitor of metalloproteinase-2 (TIMP-2) and the activation of the membrane type1-MMP (MT1-MMP). The decrease of TIMP-2 levels in conditioned media and the increase of MT1-MMP levels in plasma membrane were observed. In addition, treatment of cells with decanoyl Arg-Val-Lys-Arg-chloromethyl ketone, an inhibitor of pro-MT1-MMP, suppressed sPLA(2)-mediated MMP-2 activation, whereas treatment with bafilomycin A1, an inhibitor of H(+)-ATPase, sustained MMP-2 activation by sPLA(2). The involvement of phosphatidylinositol 3-kinase (PI3K) and Akt in the regulation of MMP-2 activity was further suggested by the findings that PI3K and Akt were phosphorylated by sPLA(2). Expression of p85alpha and Akt mutants, or pretreatment of cells with LY294002, a PI3K inhibitor, attenuated sPLA(2)-induced MMP-2 activation and migration. Taken together, these results suggest that sPLA(2) increases the pro-MMP-2 activation and migration of fibroblasts via the PI3K and Akt-dependent pathway. Because MMP-2 is an important factor directly involved in the control of cell migration and the turnover of extracellular matrix, our study may provide a mechanism for sPLA(2)-promoted fibroblasts migration.     

mTORC2 regulates PGE2-mediated endothelial cell survival and migration

Prostaglandin E₂ (PGE₂) promotes angiogenesis by in part inducing endothelial cell survival and migration. The present study examined the role of mTOR and its two complexes, mTORC1 and mTORC2, in PGE₂-mediated endothelial cell responses. We used small interfering RNA (siRNA) to raptor or rictor to block mTORC1 or mTORC2, respectively. We observed that down-regulation of mTORC2 but not mTORC1 reduced baseline and PGE₂-induced endothelial cell survival and migration. At the molecular level, we found that knockdown of mTORC2 inhibited PGE₂-mediated Rac and Akt activation two important signaling intermediaries in endothelial cell migration and survival, respectively. In addition, inhibition of mTORC2 by prolonged exposure of endothelial cells to rapamycin also prevented PGE₂-mediated endothelial cell survival and migration confirming the results obtained with the siRNA approach. Taken together these results show that mTORC2 but not mTORC1 is an important signaling intermediary in PGE₂-mediated endothelial cell responses.     

Overexpression of integrin alphav promotes human osteosarcoma cell populated collagen lattice contraction and cell migration

Cells attach and interact with the extracellular matrix (ECM) through heterodimeric alphabeta integrin receptors. Specifically, the promiscuous alphavbeta3 integrin and the alpha2beta1 integrin receptors engage numerous matrix components to influence cell adhesion, cell motility, and matrix organization. However, the role of alphav integrin mediating cell-collagen interactions is not clear. In the in vitro cell populated collagen lattice (PCL), a model of cell-matrix interaction, integrin receptors play a role in lattice contraction. To elucidate alphav integrins' effects on cell-collagen interactions, human osteosarcoma (HOS) cells were transfected with alphav integrin (alphav-pcDNA 3.1+). Control HOS cells were transfected with pcDNA 3.1+ vector alone. HOS-alphav cell PCLs contracted to a greater degree than control HOS cell PCLs (P < or = 0.0001). RT-PCR revealed that HOS-alphav cells express both beta1 and beta3 integrins, indicating that alphav has the potential to form a partnership with either beta1 or beta3 integrin. The alphavbeta3 specific inhibitory antibody LM609 significantly retarded HOS-alphav cell PCL contraction (P < or = 0.001), suggesting that alphavbeta3 promotes enhanced HOS-alphav cell PCL contraction. When plated on plastic, control HOS cells show greater elongation compared to HOS-alphav cells. In addition, HOS-alphav cells migrated faster and to a greater degree than control HOS cells (P < or = 0.0001). The possibility that enhanced HOS-alphav cell migration and HOS-alphav cell PCL contraction was caused by increased myosin ATPase activity was examined. HOS-alphav cells showed less myosin ATPase activity than control HOS cells, by an ATP cell contraction bioassay. The enhancement of HOS-alphav cell migration and lattice contraction appears unrelated to increased myosin ATPase activity.     

Green tea catechin inhibits ephrin-A1-mediated cell migration and angiogenesis of human umbilical vein endothelial cells

Angiogenesis, the formation of new blood vessels from preexisting capillaries, is essential for tumor progression and metastasis. During tumor neovascularization, vascular endothelial growth factor and ephrin (Eph) families emerge as critical mediators of angiogenesis. The green tea catechin epigallocatechin gallate (EGCG), a tyrosine kinase inhibitor, has been demonstrated in previous studies to be an effective antiangiogenesis agent. However, the inhibitory effect of green tea catechins on ephrin-A1-mediated tumor angiogenesis has not been demonstrated yet. Thus, in this study, we investigated the molecular mechanism of ephrin-A1-mediated cell migration and angiogenesis, as well as the inhibitory effects of EGCG. Here we show that ephrin-A1 mediates endothelial cell migration and regulates vascular remodeling in tumor neovascularization in vitro. We also demonstrated that ephrin-A1-mediated cell migration required the activation of extracellular-regulated kinase (ERK-1/2) but not of phosphatidylinositol-3-kinase. The green tea catechin EGCG inhibited ephrin-A1-mediated endothelial cell migration, as well as tumor angiogenesis, in a dose-dependent manner. Furthermore, EGCG inhibited the ephrin-A1-mediated phosphorylation of EphA2 and ERK-1/2. Taken together, these data indicated that activation of ERK-1/2 plays an essential role in ephrin-A1-mediated cell migration. EGCG inhibited ephrin-A1-mediated endothelial migration and angiogenesis. It suggests a novel antiangiogenesis application of EGCG in cancer chemoprevention.     

Cyclin-dependent kinase 1-mediated phosphorylation of protein kinase N1 promotes anchorage-independent growth and migration

Protein kinase N1 (PKN1) is a member of the protein kinase C superfamily. Aberrations of PKN1 kinase activity are involved in several human pathological processes, including cancer. We found that PKN family proteins (PKN1/2/3) are phosphorylated in response to antitubulin drug-induced mitotic arrest. We identified cyclin-dependent kinase 1 (CDK1) as the corresponding kinase for PKN protein phosphorylation. CDK1 phosphorylates PKN1 at S533, S537, S562, and S916 in vitro and in cells during drug-induced mitotic arrest. Immunofluorescence staining further confirmed that PKN1 phosphorylation occurs during normal mitosis in a CDK1-dependent manner. Knockdown of PKN1 significantly inhibited anchorage-independent growth and migration without affecting proliferation in multiple cancer cell lines. We further showed that mitotic phosphorylation is essential for PKN1's oncogenic function, as the non-phosphorylatable mutant PKN1-4A failed to rescue anchorage-independent growth and migration in PKN1-knockdown cells. Thus, our findings reveal a novel regulatory mechanism for PKN1 in mitosis and its role in tumorigenesis.     

Integrin beta 1- and beta 3-mediated endothelial cell migration is triggered through distinct signaling mechanisms

Human umbilical vein endothelial cell attachment, spreading and migration on collagen and vitronectin are mediated by integrins alpha 2 beta 1 and alpha v beta 3, respectively, and these events take place in the absence of cytokines, growth factors, or chemoattractants. Cell attachment and spreading on these ligands occur in the absence of extracellular calcium, as does migration on collagen. In contrast, vitronectin-mediated migration is absolutely dependent on the presence of extracellular calcium. Cell contact with immobilized vitronectin or anti-alpha v beta 3 mAbs promotes a measurable rise in [Ca2+]i which requires an extracellular calcium source, whereas collagen, or anti- alpha 2 beta 1 mAbs fail to promote this signaling event. In fact, vitronectin-mediated migration and the rise in intracellular calcium showed the same dose dependence on extracellular calcium. While vitronectin and collagen differ in their ability to induce a calcium influx both ligands or antibodies to their respective integrins promote an equivalent increase in intracellular pH consistent with activation of the Na/H antiporter an event independent of extracellular calcium. These results support two salient conclusions. Firstly, collagen and vitronectin, through their respective integrins, promote distinct intracellular signaling events. Secondly, the alpha v beta 3 specific influx of calcium is not required for cell spreading yet appears to facilitate cellular migration on vitronectin.     

Cyclic strain-induced endothelial MMP-2: role in vascular smooth muscle cell migration

Matrix metalloproteinases (MMPs) play a vital role in vasculature response to hemodynamic stimuli via the degradation of extracellular matrix substrates. In this study, we investigated the putative role of cyclic strain-induced endothelial MMP-2 (and MMP-9) expression and release in modulating bovine aortic smooth muscle cell (BASMC) migration in vitro. Equibiaxial cyclic strain of bovine aortic endothelial cells (BAECs) leads to elevation in cellular MMP-2 (and MMP-9) expression, activity, and secretion into conditioned media, events which were time- and force-dependent. Subsequent incubation of BASMCs with conditioned media from chronically strained BAECs (5%, 24 h) significantly reduces BASMC migration (38+/-6%), an inhibitory effect which could be completely reversed by targeted siRNA 'knock-down' of MMP-2 (but not MMP-9) expression and activity in BAECs. Moreover, inhibition of strain-mediated MMP-2 expression in BAECs by protein tyrosine kinase (PTK) blockade with genistein (50 microM) was also found to completely reverse this inhibitory effect on BASMC migration. Finally, direct supplementation of recombinant MMP-2 into the BASMC migration assay was found to have no significant effect on migration. However, the effect on BASMC migration of MMP-2 siRNA transfection in BAECs could be reversed by supplementation of recombinant MMP-2 into BAEC media prior to (and for the duration of) strain. These findings reveal a potentially novel role for strain-induced endothelial MMP-2 in regulating vascular SMC migration.     

Human CC chemokine CCL23, a ligand for CCR1, induces endothelial cell migration and promotes angiogenesis

A number of chemokines induce angiogenesis and endothelial cells express several chemokine receptors. To date, only a limited number of CC chemokines for CCR1 have been reported to induce angiogenic responses. We investigated the ability of CCL23 (also known as MPIF-1, MIP-3, or CKbeta8) to promote angiogenesis, which induces chemotaxis of immune cells through CCR1. CCL23 promoted the chemotactic migration and differentiation of endothelial cells, and neovascularization in the chick chorioallantoic membrane. An N-terminal truncated form of CCL23 was at least 100-fold more potent than its intact form and was comparable to that of FGF in the angiogenic activities. Treatment with either pertussis toxin or anti-CCR1 antibody completely inhibited the CCL23-induced endothelial cell migration, indicating that endothelial cell migration was mediated through CCR1. CCL23 didn't promote the migration of HT1080 human fibrosarcoma cells that did not express CCR1. Our results suggest a role of CCL23 in angiogenesis in vitro as well as in vivo.     

Fascin1 promotes cell migration of mature dendritic cells

Dendritic cells (DCs) play central roles in innate and adaptive immunity. Upon maturation, DCs assemble numerous veil-like membrane protrusions, disassemble podosomes, and travel from the peripheral tissues to lymph nodes to present Ags to T cells. These alterations in morphology and motility are closely linked to the primary function of DCs, Ag presentation. However, it is unclear how and what cytoskeletal proteins control maturation-associated alterations, in particular, the change in cell migration. Fascin1, an actin-bundling protein, is specifically and greatly induced upon maturation, suggesting a unique role for fascin1 in mature DCs. To determine the physiological roles of fascin1, we characterized bone marrow-derived, mature DCs from fascin1 knockout mice. We found that fascin1 is critical for cell migration: fascin1-null DCs exhibit severely decreased membrane protrusive activity. Importantly, fascin1-null DCs have lower chemotactic activity toward CCL19 (a chemokine for mature DCs) in vitro, and in vivo, Langerhans cells show reduced emigration into draining lymph nodes. Morphologically, fascin1-null mature DCs are flatter and fail to disassemble podosomes, a specialized structure for cell-matrix adhesion. Expression of exogenous fascin1 in fascin1-null DCs rescues the defects in membrane protrusive activity, as well as in podosome disassembly. These results indicate that fascin1 positively regulates migration of mature DCs into lymph nodes, most likely by increasing dynamics of membrane protrusions, as well as by disassembling podosomes.     

Low-dose aspirin promotes endothelial progenitor cell migration and adhesion and prevents senescence

Circulating endothelial progenitor cells (EPCs) play a key role in restoring endothelial function and enhancing angiogenesis. However, the effects of low-dose aspirin on circulating EPCs are not well known. We investigated the effects of low-dose aspirin on EPC migration, adhesion, senescence, proliferation, apoptosis and endothelial nitric oxide synthase (eNOS) expression. EPC migration was detected by a modified Boyden chamber assay. EPC adhesion assay was performed by counting adherent cells on fibronectin-coated culture dishes. EPC senescence was assessed by both senescence-associated-beta-galactosidase staining and DAPI staining. EPC proliferation was analyzed by MTT assay. EPC apoptosis was evaluated by flow cytometric analysis. eNOS protein expression was measured by Western blotting analysis. Aspirin promoted EPC migratory and adhesive capacity at concentrations between 0.1 and 100micromol/L and prevented senescence at concentrations between 50 and 100micromol/L. Meanwhile, aspirin in a range of these concentrations did not affect EPC proliferation, apoptosis or eNOS expression. Our findings indicate that low-dose aspirin promotes migration and adhesion and delays the onset of senescence of EPCs.     

Activation of EGFR promotes squamous carcinoma SCC10A cell migration and invasion via inducing EMT-like phenotype change and MMP-9-mediated degradation of E-cadherin

EGFR is a potent stimulator of invasion and metastasis in head and neck squamous cell carcinomas (HNSCC). However, the mechanism by which EGFR may stimulate tumor cell invasion and metastasis still need to be elucidated. In this study, we showed that activation of EGFR by EGF in HNSCC cell line SCC10A enhanced cell migration and invasion, and induced loss of epitheloid phenotype in parallel with downregulation of E-cadherin and upregulation of N-cadherin and vimentin, indicating that EGFR promoted SCC10A cell migration and invasion possibly by an epithelial to mesenchymal transition (EMT)-like phenotype change. Interestingly, activation of EGFR by EGF induced production of matrix metalloproteinase-9 (MMP-9) and soluble E-cadherin (sE-cad), and knockdown of MMP-9 by siRNA inhibited sE-cad production induced by EGF in SCC10A. Moreover, both MMP-9 knockdown and E-cadherin overexpression inhibited cell migration and invasion induced by EGF in SCC10A. The results indicate that EGFR activation promoted cell migration and invasion through inducing MMP-9-mediated degradation of E-cadherin into sE-cad. Pharmacologic inhibition of EGFR, MEK, and PI3K kinase activity in SCC10A reduced phosphorylated levels of ERK-1/2 and AKT, production of MMP-9 and sE-cad, cell migration and invasion, and expressional changes of EMT markers (E-cadherin and N-cadherin) induced by EGF, indicating that EGFR activation promotes cell migration and invasion via ERK-1/2 and PI3K-regulated MMP-9/E-cadherin signaling pathways. Taken together, the data suggest that EGFR activation promotes HNSCC SCC10A cell migration and invasion by inducing EMT-like phenotype change and MMP-9-mediated degradation of E-cadherin into sE-cad related to activation of ERK-1/2 and PI3K signaling pathways.     

Ganglioside GD1a enhances VEGF-induced endothelial cell proliferation and migration

Tumor progression requires normally quiescent endothelial cells to form new vascular networks. This angiogenesis is dependent upon several soluble factors, prominent among which is vascular endothelial growth factor (VEGF). Other tumor-associated molecules, such as gangliosides, sialic acid-containing glycosphingolipids expressed by tumor cells and shed into the tumor microenvironment, may also modulate tumor angiogenesis. Here we assessed the influence of a highly purified ganglioside, G(D1a), on responses of normal human umbilical vein endothelial cells (HUVEC) to VEGF. Preincubation of HUVEC with G(D1a) enhanced VEGF-induced cell proliferation; 10 microM G(D1a) caused a twofold increase in DNA synthesis. The migration of HUVEC across a VEGF gradient was also enhanced by 50%, even with only a brief (1 h) preexposure of the cells to the same concentration of G(D1a). These findings suggest that gangliosides shed by tumor cells can promote tumor angiogenesis by enhancing the VEGF response of endothelial cells in the tumor microenvironment.     

Aquaporin-1 plays a key role in erythropoietin-induced endothelial cell migration

Water influx through aquaporin-1 (AQP-1) has been linked to the ability of different cell types to migrate, and therefore plays an important part in processes like metastasis and angiogenesis. Since the erythroid growth factor erythropoietin (Epo) is now recognized as an angiogenesis promoter, we investigated the participation of AQP-1 as a downstream effector of this cytokine in the migration of endothelial cells. Inhibition of AQP-1 with either mercury ions (Hg²⁺) or a specific siRNA led to an impaired migration of EA.hy926 endothelial cells exposed to Epo (wound-healing assays). Epo also induced the expression of AQP-1 at mRNA and protein levels, an effect which was dependent on the influx of extracellular calcium through L-type calcium channels as well as TRPC3 channels.The relationship between Epo and AQP-1 was further confirmed at shorter exposure times, as the cytokine was unable to trigger calcium influxes in cells where AQP-1 had previously been knocked down. Moreover, Epo promoted changes in the subcellular localization of AQP-1 as well as rearrangements in the actin cytoskeleton, which are consistent with a migratory phenotype. Worthy of note, carbamylated erythropoietin (cEpo), the non-erythropoietic and non-promigratory derivative of Epo, was incapable of AQP-1 modulation.The therapeutical implications of aquaporin targeting in angiogenesis-related diseases highlight the importance of the present results in the context of the relationship between AQP-1 and Epo.     

Overexpression of RhoGDI,a novel predictor of distant metastasis,promotes cell proliferation and migration in hepatocellular carcinoma

RhoGDI (Rho GDP-dissociation inhibitor alpha, or RhoGDIα) was identified as a regulator of Rho GTPases, but its role in cancer remains controversial. In this study, increased expression of RhoGDI was detected in hepatocellular carcinoma (HCC) cell lines and tissues with highly metastatic potential. RhoGDI overexpression correlated with postoperative distant metastasis. Enforced expression of RhoGDI in HCC cells significantly enhanced cell proliferation and migration. Conversely, knockdown of RhoGDI caused an inhibition of the aggressive phenotypes of HCC cells. Furthermore, RhoGDI up-regulated Rho, but not Rac, and enhanced PI3K/AKT and MAPK pathway activity. Our findings suggest that RhoGDI overexpression is a predictor of distant metastasis and plays an important role in the progression of HCC.     

Human hemokinin-1 promotes migration of melanoma cells and increases MMP-2 and MT1-MMP expression by activating tumor cell NK1 receptors

Receptors and their regulatory peptides are aberrantly expressed in tumors, suggesting a potential tumor therapy target. Human hemokinin-1 (hHK-1) is a tachykinin peptide ligand of the neurokinin-1 (NK1) receptor which is overexpressed in melanoma and other tumor tissues. Here, we investigated the role of hHK-1 and the NK1 receptor in melanoma cell migration. NK1 receptor expression was associated with melanoma metastatic potential. Treatment with hHK-1 significantly enhanced A375 and B16F10 melanoma cell migration and an NK1 receptor antagonist L732138 blocked this effect. MMP-2 and MT1-MMP expression were up-regulated in hHK-1-treated melanoma cells and cell signaling data suggested that hHK-1 induced phosphorylation of ERK1/2, JNK and p38 by way of PKC or PKA. Kinase activation led to increased MMP-2 and MT1-MMP expression and melanoma cell migration induced by hHK-1. Thus, hHK-1 and the NK1 receptor are critical to melanoma cell migration and each may be a promising chemotherapeutic target.