Absence Of Hepatocyte Growth Factor Research Articles

Crk associates with a multimolecular Paxillin/GIT2/beta-PIX complex and promotes Rac-dependent relocalization of Paxillin to focal contacts.

We have previously demonstrated that the CrkII and CrkL adapter proteins are required for the spreading of epithelial colonies and the breakdown of adherens junctions in response to hepatocyte growth factor. When overexpressed, CrkII and CrkL promote lamellipodia formation, cell spreading, and the loss of epithelial adherens junctions in the absence of hepatocyte growth factor. The exact mechanism by which Crk proteins elicit these changes is unclear. We show that the overexpression of CrkII or CrkL, but not Src homology 2 or amino-terminal Src homology 3 domain mutant Crk proteins, promotes the relocalization of Paxillin to focal contacts throughout the cell and within lamellipodia in a Rac-dependent manner. In stable cell lines overexpressing CrkII, enhanced lamellipodia formation and cell spreading correlate with an increased association of CrkII with Paxillin, GIT2 (an ARF-GAP) and beta-PIX (a Rac1 exchange factor). Mutants of Paxillin that fail to associate with Crk or GIT2, or do not target to focal adhesions inhibit Crk-dependent cell spreading and lamellipodia formation. We conclude from these studies that the association of Crk with Paxillin is important for the spreading of epithelial colonies, by influencing the recruitment of Paxillin to focal complexes and promoting the enhanced assembly of Paxillin/GIT2/beta-PIX complexes.

HGF, MAPK, and a small physiological electric field interact during corneal epithelial cell migration.

To investigate the effects of hepatocyte growth factor (HGF) and a small applied electric field (EF) on corneal epithelial cell (CEC) migration. Primary cultures of bovine CECs were exposed to an EF (25-250 mV/mm) in the presence or absence of HGF (100 ng/mL). The rate and directionality of CEC migration were quantified. The expression of HGF receptors (HGFRs), p42/44 mitogen-activated protein kinase (MAPK) and the time-course of activation of p42/44 MAPK were investigated by confocal microscopy and Western blot analysis. CECs migrated significantly faster in the presence of an EF, HGF, or HGF and an EF combined. The distribution of HGFRs was intracellular and in the presence of an EF was concentrated in the cathode-facing side. This EF-induced asymmetrical accumulation of HGFRs correlated with the direction of CEC migration. The application of HGF or an EF led to the activation of the MAPK signaling pathway and in the presence of an EF, activation of MAPK was greater in the cathode-facing half of the CECs. Inhibition of the MAPK signaling pathway by PD98059 (100 micro M) reduced the ability of HGF and an EF to enhance the rate of CEC migration, but did not alter EF-induced cathodal directionality. These data suggest that both HGF and an EF augment the rate of CEC migration through activation of p42/44 MAPK. Moreover, EF-induced redistribution of HGFRs and asymmetry of MAPK signaling, although not instrumental in directing CEC migration cathodally, may be important for the signaling and maintenance of migration.

Hepatocyte growth factor inhibits insulin-stimulated glycogen synthesis in primary cultured hepatocytes

Background/Aims: Hepatocyte growth factor (HGF) plays an important role as a mitogen in liver regeneration. However, little is known about the metabolic effects of HGF in the liver. Studies were performed to examine whether HGF influences carbohydrate metabolism, which is drastically changed in the early course of the regeneration. Methods: Primary cultured rat hepatocytes were treated with glucoregulatory hormones such as insulin, glucagon and adrenaline in the presence or absence of HGF. Cellular glycogen deposition and activities of its metabolic enzymes were compared. Results: HGF inhibited insulin-stimulated glycogen deposition, but had no effect on glycogen degradation stimulated by glucagon and adrenaline. HGF decreased glycogen synthase activity and increased glycogen phosphorylase activity in insulin-stimulated hepatocytes, resulting in the inhibition of glycogen synthesis. Experiments with immunoprecipitation revealed that HGF had no effect on the upstream of insulin signaling including an activation of its receptor and association of insulin receptor substrate with phosphatidylinositol 3-kinase, indicating that HGF presumably affects further downstream of these events. Conclusions: These results demonstrate that HGF interacts with insulin on glucose metabolism in hepatocytes. HGF may be involved in glucose regulation, and contribute to cell growth and maturation in addition to its mitogenic action during liver regeneration.

Effects of hepatocyte growth factor on the expression of matrix metalloproteinases and their tissue inhibitors during the endometrial cancer invasion in a three-dimensional coculture

Matrix metalloproteinase (MMP)-2 and -9 are secreted and translocated from endometrial stromal cells to HEC-1 A cells in a steroid-dependent manner. We investigated the paracrine effect of hepatocyte growth factor (HGF) on MMPs and metalloproteinase tissue inhibitor (TIMP) expression in stromal and endometrial cancer cells, and correlated with cancer cell invasiveness in three-dimensional (3D) coculture. The 3D coculture of endometrial stromal and cancer cell lines (HEC-1 A, HEC-IB, or KLE) were maintained in the presence or absence of HGF. The expression of MMP-2 and -9, MT1-MMP, TIMP-1 and -2 were examined by RT-PCR and zymography. Under the same conditions, invasion of the cancer cells was quantified by Boyden's chamber assay. HGF strongly induced MMP-9 mRNA expression in stromal cells, but had little effect on MMP-2 mRNA. MT1-MMP mRNA was detected only in KLE and stromal cells, which was also increased by HGF. TIMP-1 and -2 mRNAs was ubiquitous with no dependence on HGF. Zymographic analysis of MMPs showed that activation of MMP-2 and -9 was enhanced by HGF. A significant increase in invasion of all three cancer cells with HGF was observed. The effect of HGF on the invasiveness of 3D cocultured endometrial cancer cells and stromal cells appears to be due to induction of MMP-9 mRNA expression in stromal cells and /or increased activation of MMP-2 and MMP-9 by proteolytic digestion.

Effects of hepatocyte growth factor on the expression of matrix metalloproteinases and their tissue inhibitors during the endometrial cancer invasion in a three-dimensional coculture.

Matrix metalloproteinase (MMP)-2 and -9 are secreted and translocated from endometrial stromal cells to HEC-1 A cells in a steroid-dependent manner. We investigated the paracrine effect of hepatocyte growth factor (HGF) on MMPs and metalloproteinase tissue inhibitor (TIMP) expression in stromal and endometrial cancer cells, and correlated with cancer cell invasiveness in three-dimensional (3D) coculture. The 3D coculture of endometrial stromal and cancer cell lines (HEC-1 A, HEC-IB, or KLE) were maintained in the presence or absence of HGF. The expression of MMP-2 and -9, MT1-MMP, TIMP-1 and -2 were examined by RT-PCR and zymography. Under the same conditions, invasion of the cancer cells was quantified by Boyden's chamber assay. HGF strongly induced MMP-9 mRNA expression in stromal cells, but had little effect on MMP-2 mRNA. MT1-MMP mRNA was detected only in KLE and stromal cells, which was also increased by HGF. TIMP-1 and -2 mRNAs was ubiquitous with no dependence on HGF. Zymographic analysis of MMPs showed that activation of MMP-2 and -9 was enhanced by HGF. A significant increase in invasion of all three cancer cells with HGF was observed. The effect of HGF on the invasiveness of 3D cocultured endometrial cancer cells and stromal cells appears to be due to induction of MMP-9 mRNA expression in stromal cells and /or increased activation of MMP-2 and MMP-9 by proteolytic digestion.

Functional role of hepatocyte growth factor receptor during sperm maturation.

Mammalian spermatozoa acquire motility and fertilizing capacity during their transit through the epididymis. Hepatocyte growth factor (HGF) is a pleiotropic cytokine with potent motogenic capacities that has been identified in different organs, including the mammalian male genital tract. In mice, HGF is present in the testis and, in large amounts, in the distal part of the epididymis. In prepuberal rats, we have demonstrated that HGF is synthesized by the peritubular myoid cells and in men, HGF is present in significant quantities in seminal plasma. It has been suggested that in mice, HGF has a role in initiating sperm motility, whereas in men, no significant correlations between HGF concentration and sperm motility have been found. In the present paper we report that in rats, HGF receptor, c-met, is expressed in testicular and epididymal spermatozoa. Through immunocytochemistry, we have found that c-met is exclusively localized on the head in testicular sperm. A different localization of c-met has been found in sperm isolated from caput and cauda epididymidis. Cells isolated from epididymal caput show a c-met localization exclusively restricted to the head in most cells. In a minority of caput epididymis spermatozoa the receptor is localized both in the cell head and along the flagellum. Spermatozoa isolated from the epididymal cauda were quite homogeneous, showing the receptor localized along the entire cell surface. We also report that HGF is synthesized and secreted by the rat epididymis as indicated by the scatter effect of epididymal cell homogenate and culture medium on MDCK cells. To clarify whether HGF is involved in the acquisition of sperm motility in the epididymis, its maintenance, or both, spermatozoa isolated from caput epididymidis have been cultured in medium alone or supplemented with HGF. The results obtained indicated that HGF has a positive effect on the maintenance of sperm motility which, in the absence of HGF, significantly decreases during the first hour of culture, whereas it is maintained for at least 3 hours when HGF is present in the culture medium. We also report that HGF does not influence spermatozoa viability as indicated by the cytometrical analysis of propidium iodide-labeled sperm; an equal number of dead cells appeared in control and in HGF-treated preparations. In conclusion, our data strongly support the hypothesis that HGF positively influences sperm motility maintenance during sperm transit through the epididymis, indicating that c-met receptor and its ligand, HGF, have a role in male fertility.

Crk adapter proteins promote an epithelial-mesenchymal-like transition and are required for HGF-mediated cell spreading and breakdown of epithelial adherens junctions.

Activation of the Met receptor tyrosine kinase through its ligand, hepatocyte growth factor (HGF), promotes an epithelial-mesenchymal transition and cell dispersal. However, little is known about the HGF-dependent signals that regulate these events. HGF stimulation of epithelial cell colonies leads to the enhanced recruitment of the CrkII and CrkL adapter proteins to Met-dependent signaling complexes. We provide evidence that signals involving CrkII and CrkL are required for the breakdown of adherens junctions, the spreading of epithelial colonies, and the formation of lamellipodia in response to HGF. The overexpression of a CrkI SH3 domain mutant blocks these HGF-dependent events. In addition, the overexpression of CrkII or CrkL promotes lamellipodia formation, loss of adherens junctions, cell spreading, and dispersal of colonies of breast cancer epithelial cells in the absence of HGF. Stable lines of epithelial cells overexpressing CrkII show enhanced activation of Rac1 and Rap1. The Crk-dependent breakdown of adherens junctions and cell spreading is inhibited by the expression of a dominant negative mutant of Rac1 but not Rap1. These findings provide evidence that Crk adapter proteins play a critical role in the breakdown of adherens junctions and the spreading of sheets of epithelial cells.

The SH2-containing inositol 5-phosphatase (SHIP)-1 is implicated in the control of cell-cell junction and induces dissociation and dispersion of MDCK cells.

Hepatocyte growth factor (HGF) induces the breakdown of cell junction and the dispersion of colonies of epithelial cells, providing a model system for the investigation of the molecular mechanisms of one of the important aspects of tumorogenesis. We have previously reported that the SH2-domain-containing inositol 5'phosphatase (SHIP)-1 binds to c-Met, and potentiated HGF-mediated branching tubulogenesis. In this study, we describe the establishment of MDCK cell lines which express MycHis-tagged SHIP-1 at different levels. Expression of SHIP-1 in MDCK cells at a high level resulted in cell morphology characteristic of an epithelial-mesenchymal like transition; cells lost cortical actin, developed actin stress fibers and gained spontaneous motility without treatment of HGF. When the level of MycHis-tagged SHIP-expression was relatively low, transfectants partially lost cortical actin and phalloidin stained puncta appeared at cell-cell junctions even in the absence of HGF. The treatment of MAP kinase inhibitor, PD98059, did not influence SHIP-1 mediated alteration of adherens-junction of MDCK cells, while, phosphatidylinositol 3 (PI 3)- kinase inhibitor, LY294002, drastically reduced SHIP-1 mediated phenotype. Furthermore, expression of a mutant SHIP-1 lacking catalytic activity in MDCK cells did not alter the cortical actin distribution and HGF-mediated MAP and Akt kinase-phosphorylation, but suppressed HGF induced cell dispersion, suggesting that phosphatase activity is important for cytoskeleton rearrangement and cell dispersion.

Increase in hepatocyte growth factor receptor tyrosine kinase activity in renal carcinoma cells is associated with increased motility partly through phosphoinositide 3-kinase activation.

Dysregulated cell motility is one of the major characteristics of invasion and metastatic potentials of malignant tumor cells. Here, we examined the hepatocyte growth factor (HGF)-induced cell motility of two human renal carcinoma cell lines, ACHN and VMRC-RCW. Scattering and migration was induced in ACHN in an HGF-dependent manner, whereas they were maintained in VMRC-RCW even in the absence of HGF. In VMRC-RCW, HGF receptor (HGFR) tyrosine kinase was constitutively active, and sequence analysis showed N375S, A1209G and V1290L mutations. However, transfection experiments using porcine aortic endothelial (PAE) cells demonstrated that no single mutation or combination of two or three mutations caused HGF-independent constitutive activation. Conversely, the expressed amount of receptor protein had a pivotal role in the basal kinase activity. With respect to downstream signaling molecules of HGFR in ACHN or VMRC-RCW, the Ras-MAPK pathway was downregulated, whereas phosphoinositide 3-kinase (PI3-kinase) was not further activated by HGF-treatment in VMRC-RCW cells. The PI3-kinase inhibitors, wortmannin and LY294002 strongly inhibited spontaneous migration of VMRC-RCW. One transfected PAE cell line with massive overexpression of HGFR demonstrated scattered morphology and increased PI3-kinase activity in association with increased motility, which was partially inhibited by LY294002. Taken together, our results indicate that the overexpression of HGFR causes increase in cellular motility and PI3-kinase shows the important contribution on the increased motility of renal carcinoma cells.

Morphogenesis of primary human biliary epithelial cells: induction in high-density culture or by coculture with autologous human hepatocytes.

Although the control of biliary ductular morphogenesis has received some attention particularly using isolated rat biliary epithelial cell models, the regulation of human bile duct formation is not well defined. In the present study, using a 3-dimensional culture model comprising primary human biliary epithelial cells (BECs) and coculture with primary human hepatocytes, we have sought to define the factors involved. We have shown that primary human BECs can be expanded on collagen gels in the absence of growth factors or serum. When plated in high density in double collagen gels, BECs established 3-dimensional structures that subsequently developed into well differentiated polarized luminal ducts. This morphogenic response occurred in the absence of hepatocyte growth factor (HGF) and epidermal growth factor. Strikingly, the addition of growth factors (in the presence of serum) resulted in loss of polarity although the cells retained growth responses to both factors. Coculture of BECs with autologous human hepatocytes enhanced the ability of low-density BECs to undergo ductulogenesis. This effect was mimicked by addition of conditioned medium from previous hepatocyte-BEC cocultures. These findings indicate that for human biliary ductular morphogenesis, epithelial cell-cell interactions are required but that mesenchymally derived factors such as HGF may not be important.

Hepatocyte Growth Factor, but Not Insulin-Like Growth Factor I, Protects Podocytes against Cyclosporin A-Induced Apoptosis

Cyclosporin A (CsA) nephropathy is associated with altered expression of apoptosis regulatory genes such as Fas-ligand and Bcl-2 family members in the glomerular, tubulointerstitial, and vascular compartments. Both hepatocyte growth factor (HGF) and insulin-like growth factor (IGF-I) protect against apoptosis, and HGF specifically up-regulates Bcl-xL, a protein that regulates apoptosis. We investigated whether Bcl-xL and Fas/Fas-ligand were regulated by CsA in cultured podocytes and whether CsA-induced apoptosis was prevented by HGF or IGF-I. A murine podocyte cell line was treated with CsA in the presence or absence of HGF or IGF-I. Apoptosis was quantitated by ELISA and by flow cytometry; Bcl-xL, Fas, and Fas-ligand were measured by Western blotting. Inhibitors of MAP kinase/ERK kinase (MEK)-1 and of phosphatidylinositol 3'-kinase (PI3'-K) were used to determine the signaling pathways involved in Bcl-xL regulation. Apoptosis was induced by CsA in a dose- and time-dependent fashion. CsA also decreased Bcl-xL levels. HGF, but not IGF-I, prevented apoptosis and restored Bcl-xL levels. The regulation of Bcl-xL by HGF was mediated by the PI3'-K but not by the MEK-1 pathway. In summary, we showed that CsA induces apoptosis in podocytes. Apoptosis was prevented by pretreatment with HGF but not IGF-I. Decreased apoptosis appeared to be mediated by regulation of Bcl-xL via the PI3'-K pathway. Our data suggest that the effect of CsA on podocytes may contribute to the glomerular damage and that HGF could provide protection.

Cross-talk between Epidermal Growth Factor Receptor and c-Met Signal Pathways in Transformed Cells

In rat liver epithelial cells constitutively expressing transforming growth factor alpha (TGFalpha), c-Met is constitutively phosphorylated in the absence of its ligand, hepatocyte growth factor. We proposed that TGFalpha and the autocrine activation of its receptor, epidermal growth factor receptor (EGFR), leads to phosphorylation and activation of c-Met. We found that there is constitutive c-Met phosphorylation in human hepatoma cell lines and the human epidermoid carcinoma cell line, A431 which express TGFalpha, but not in normal human hepatocytes. Constitutive c-Met phosphorylation in A431, HepG2, AKN-1, and HuH6 cells was inhibited by neutralizing antibodies against TGFalpha and/or EGFR. Exposure to exogenous TGFalpha or EGF increased the phosphorylation of c-Met in the human epidermoid carcinoma cell line, A431. The increase of c-Met phosphorylation by TGFalpha in A431 cells was inhibited by neutralizing antibodies against TGFalpha and/or EGFR and by the EGFR-specific inhibitor tyrphostin AG1478. These results indicate that constitutive c-Met phosphorylation, and the increase of c-Met phosphorylation by TGFalpha or EGF, in tumor cell lines is the result of the activation via EGFR. We found that c-Met in tumor cells co-immunoprecipitates with EGFR regardless of the existence of their ligands in tumor cells, but not in normal human hepatocytes. We conclude that c-Met associates with EGFR in tumor cells, and this association facilitates the phosphorylation of c-Met in the absence of hepatocyte growth factor. This cross-talk between c-Met and EGFR may have significant implications for altered growth control in tumorigenesis.

Enhancement by hepatocyte growth factor of bone and cartilage formation during embryonic mouse mandibular development in vitro

To elucidate the possible roles of hepatocyte growth factor (HGF) in the early development of mouse mandible, HGF was applied to an organ-culture system with chemically defined media. Mandibular arches microdissected from mouse embryos at the 10th day of gestation were cultured for 10 days with or without HGF, HGF plus HGF-receptor (c-met) antisense oligodeoxyribonucleotide, or HGF plus c-met sense oligodeoxyribonucleotide in the media. The cultured mandibles were then analysed histologically in serial paraffin sections. In the absence of HGF, the tooth organs of bud stage, Meckel’s cartilage and the tongue were formed, whereas only a slight amount of bone tissue was formed in the cultured mandible. The expression of intrinsic HGF and c-met in the cultured mandibles was confirmed by reverse transcriptase–polymerase chain reaction. Furthermore, immunohistochemistry demonstrated that both HGF and c-met were localized in areas of the mesenchymal tissue forming bone and cartilage. With HGF in the medium, the volume of both bone and cartilage increased significantly and dose-dependently. HGF also increased the rate of proliferation of osteogenic cells and chondrocytes. Addition of c-met antisense oligodeoxyribonucleotide partially inhibited the HGF-induced enhancement of bone and cartilage formation, whereas addition of c-met sense oligodeoxyribonucleotide had no effect. These results revealed that exogenous HGF enhances bone and cartilage morphogenesis in the cultured mandibles, suggesting physiological roles for intrinsic HGF in the early development of mouse mandible.

Hepatocyte growth factor stimulates the invasion of gallbladder carcinoma cell lines in vitro.

Human gallbladder cancer is highly malignant and its prognosis is usually poor depending on the extent of surrounding tissue invasion. We examined in vitro the invasive activity of four gallbladder cancer cell lines (GB-d1, GB-h3, GB-d2 and FU-GBC-1) in the absence or presence of hepatocyte growth factor (HGF). In type 1 collagen gel culture, HGF stimulated cell proliferation and induced an invasive phenotype of arborizing structures in GB-d1, GB-h3 and GB-d2. In a Matrigel invasion assay, invasion was also induced in three of these cell lines by HGF but not in FU-GBC-1. Cellular motility was, however, stimulated by HGF in all of the four cell lines to various extents. Zymography for proteolytic enzymes demonstrated high levels of type IV collagenase and urokinase-type plasminogen activator (u-PA) activity in GB-d1, GB-h3 and GB-d2 even in the absence of HGF. In the presence of HGF, the 72 kDa type IV collagenase (MMP-2) activity of GB-h3 and u-PA activities of GB-d1, GB-h3 and GB-d2 were enhanced. In contrast, the MMPs and PAs activities of FU-GBC-1 were faint irrespective of the addition of HGF. A Western blot analysis demonstrated higher levels of 190 kDa c-MET product (HGF receptor) of GB-d1, GB-h3 and GB-d2 than that of FU-GBC-1. The invasion in the Matrigel assay stimulated by HGF was inhibited by protease inhibitors, aprotinin and FOY-305, as well as by anti-HGF antibody. These results thus suggest that, in addition to the importance of the proteolytic activity, the cellular motility induced via the HGF/HGF-receptor system is essential for the invasive progression of gallbladder carcinoma cells.

Hepatocyte Growth Factor as a Potent Survival Factor for Rat Pheochromocytoma PC12 Cells

Hepatocyte growth factor (HGF), a natural ligand for the c-met protooncogene product, is a multipotent polypeptide which elicits mitogenic, motogenic, and morphogenic activities for various types of cells. To better understand the biological activity of HGF, as related to neuroectodermal-derived cells, we investigated the effects of HGF on rat pheochromocytoma PC12 cells. HGF increased the number of PC12 cells during long culture, but elicited no direct mitogenic activity, as determined by DNA synthesis. When the cells were cultured in medium containing lower concentrations of fetal calf serum, HGF prolonged the survival of PC12 cells; the number of cells did not decrease during 13 days when the cells were cultured in the presence of HGF, but the cells were completely withdrawn when cultured in the absence of HGF. Nerve growth factor but not HGF induced the differentiation of PC12 cells. High affinity receptor for HGF with Kd values of 20-40 pM was expressed in PC12 cells and other types of cells derived from the central nervous tissue: T98G cells (human glioblastoma), GOTO, and SCCH-26 cells (human neuroblastoma). HGF stimulated motility of T98G cells, while it induced weak mitogenic response in GOTO cells. We suggest that HGF is a potent survival factor for PC12 cells, without exerting any direct mitogenic activity and inducing the cell differentiation, and that this factor may have a distinct biological activity for neuroectoderm-derived cells.

Apoptosis of serum-free C2.8 mouse embryo hepatocytic cells caused by hepatocyte growth factor deprivation.

C2.8 mouse embryo hepatocytic cells, acutely required exogenous hepatocyte growth factor (HGF) to survive and proliferate in serum-free Dulbecco's modified Eagle's medium supplemented with insulin, transferrin and Na-selenite. Greater than 90% of cultured C2.8 cells died within 48 hours from plating in the absence of HGF. Conversely, HGF prolonged maintenance of life and stimulated cell proliferation. Removal of HGF from the medium of cultures that had grown to confluency, also resulted in a rapid decreased cell survival. In the last circumstance, light microscopic observations revealed, with high frequency, morphological features characteristic of apoptosis. DNA within the affected cells underwent rapid fragmentation, revealed as a ladder of DNA fragments in multiples of about 200 base pairs. HGF prevented loss of cell viability, morphological damages and retarded DNA fragmentation in confluent C2.8 cells. Cycloheximide delayed cell death caused by HGF deprivation.