Scatter factor induces blood vessel formation in vivo

Decreased Serum Hepatocyte Growth Factor (HGF) in Individuals with Bipolar Disorder Normalizes after Zinc and Anti-oxidant Therapy

Aim:

To assess serum HGF concentration in individuals with bipolar disorder and investigate the efficacy of zinc therapy on these levels.

Subjects and methods:

Serum from 35 individuals diagnosed with bipolar disorder and 19 age and gender similar controls were tested for HGF concentration using ELISAs, and copper and zinc plasma levels using inductively-coupled plasma-mass spectrometry.

Results:

HGF serum levels of individuals with bipolar disorder were significantly lower than age and gender similar controls (P = 0.0021). HGF serum concentration was significantly lower in Bipolar patients pre-therapy (P = 0.0009) and HGF levels normalized post-therapy. Zinc levels in these same individuals also normalized (P = 0.0046) and patient’s perceived severity of Bipolar symptoms significantly decreased after therapy (P = 0.0003). We also found a significant direct correlation between Zinc and HGF serum concentration in the bipolar patients (P = 0.04).

Discussion:

These results suggest an association between low HGF levels and bipolar disorder and also demonstrate that zinc therapy may be associated with the normalization of HGF levels and decrease in severity of disease.

Cancer cell-derived IL-1α promotes HGF secretion by stromal cells and enhances metastatic potential in pancreatic cancer cells

BACKGROUND AND OBJECTIVES

Interleukin (IL)-1α and hepatocyte growth factor (HGF) play an important role in pancreatic cancer proliferation, angiogenesis, and invasiveness. The aim of this study was to investigate the cooperative role of HGF and IL-1α in metastatic processes promoted by interactions between pancreatic cancer cells and stromal cells.

METHODS

Expression of IL-1α and HGF mRNA and protein was determined by RT-PCR and ELISA. The effect of HGF on metastatic potential was evaluated by proliferation, invasion, and angiogenesis assays using an in vitro system consisting of co-cultured tumor cells and stromal cells.

RESULTS

IL-1α expression was closely correlated with metastatic potential, and cancer cell-derived IL-1α significantly promoted HGF expression by fibroblasts (P < 0.01). HGF not only enhanced the invasiveness and proliferation of pancreatic cancer cells, but also enhanced migration and proliferation of human umbilical vein endothelial cells (HUVECs). HGF significantly enhanced HUVEC tube formation (P < 0.01). Furthermore, the high liver-metastatic pancreatic cancer cell line (BxPC-3), which secretes IL-1α, significantly enhanced HUVEC tube formation compared with the low liver-metastatic cell line (Capan-2), which does not produce IL-1α (P < 0.01).

CONCLUSION

Autocrine IL-1α and paracrine HGF co-enhance the metastatic potential of pancreatic cancer cells via both IL-1α and HGF signaling pathways.

Allosteric peptide activators of pro-hepatocyte growth factor stimulate Met signaling

Hepatocyte growth factor (HGF) binds to its target receptor tyrosine kinase, Met, as a single-chain form (pro-HGF) or as a cleaved two-chain disulfide-linked α/β-heterodimer. However, only two-chain HGF stimulates Met signaling. Proteolytic cleavage of the Arg(494)-Val(495) peptide bond in the zymogen-like pro-HGF results in allosteric activation of the serine protease-like β-chain (HGF β), which binds Met to initiate signaling. We use insights from the canonical trypsin-like serine protease activation mechanism to show that isolated peptides corresponding to the first 7-10 residues of the cleaved N terminus of the β-chain stimulate Met phosphorylation by pro-HGF to levels that are ∼25% of those stimulated by two-chain HGF. Biolayer interferometry data demonstrate that peptide VVNGIPTR (peptide V8) allosterically enhances pro-HGF β binding to Met, resulting in a K(D)(app) of 1.6 μm, only 8-fold weaker than the Met/HGF β-chain affinity. Most notably, in vitro cell stimulation with peptide V8 in the presence of pro-HGF leads to Akt phosphorylation, enhances cell survival, and facilitates cell migration between 75 and 100% of that found with two-chain HGF, thus revealing a novel approach for activation of Met signaling that bypasses proteolytic processing of pro-HGF. Peptide V8 is unable to enhance Met binding or signaling with HGF proteins having a mutated activation pocket (D672N). Furthermore, Gly substitution of the N-terminal Val residue in peptide V8 results in loss of all activity. Overall, these findings identify the activation pocket of the serine protease-like β-chain as a "hot spot" for allosteric regulation of pro-HGF and have broad implications for developing selective allosteric activators of serine proteases and pseudoproteases.

Gene expression analysis identifies potential biomarkers of neurofibromatosis type 1 including adrenomedullin

PURPOSE

Plexiform neurofibromas (pNF) are Schwann cell tumors found in a third of individuals with neurofibromatosis type 1 (NF1). pNF can undergo transformation to malignant peripheral nerve sheath tumors (MPNST). There are no identified serum biomarkers of pNF tumor burden or transformation to MPNST. Serum biomarkers would be useful to verify NF1 diagnosis, monitor tumor burden, and/or detect transformation.

EXPERIMENTAL DESIGN

We used microarray gene expression analysis to define 92 genes that encode putative secreted proteins in neurofibroma Schwann cells, neurofibromas, and MPNST. We validated differential expression by quantitative reverse transcription-PCR, Western blotting, and ELISA assays in cell conditioned medium and control and NF1 patient sera.

RESULTS

Of 13 candidate genes evaluated, only adrenomedullin (ADM) was confirmed as differentially expressed and elevated in serum of NF1 patients. ADM protein concentrati on was further elevated in serum of a small sampling of NF1 patients with MPNST. MPNST cell conditioned medium, containing ADM and hepatocyte growth factor, stimulated MPNST migration and endothelial cell proliferation.

CONCLUSIONS

Thus, microarray analysis identifies potential serum biomarkers for disease, and ADM is a serum biomarker of NF1. ADM serum levels do not seem to correlate with the presence of pNFs but may be a biomarker of transformation to MPNST.

Decreased Serum Hepatocyte Growth Factor (HGF) in Individuals with Anxiety Increases After Zinc Therapy

Aim:

To assess serum Hepatocyte Growth Factor (HGF) levels in individuals with anxiety and to test the hypothesis that there is a relationship between HGF levels and zinc therapy.

Subjects and methods:

Serum from 19 individuals with anxiety and 19 controls were tested for serum HGF using ELISAs. HGF serum concentration in individuals with anxiety before zinc and anti-oxidant therapy was compared to levels after therapy. Zinc and copper levels in anxiety patients, pre and post therapy, were also measured and compared.

Results:

Individuals with anxiety had significantly lower serum levels of HGF compared to controls (P = 0.0005). HGF concentration rose significantly (normalized) after zinc therapy (P = 0.04) and zinc levels increased significantly in these same patients (P = 0.0002).

Discussion:

These results suggest an association between HGF serum levels and individuals with anxiety and demonstrate that zinc therapy is associated with increasing HGF levels.

Decreased Serum Hepatocyte Growth Factor (HGF) in Individuals with Depression Correlates with Severity of Disease

AIM

To assess serum Hepatocyte Growth Factor (HGF) levels in individuals with depression and to test the hypothesis that there is a relationship between severity of depression and HGF concentration.

SUBJECTS AND METHODS

Serum from 26 clinically depressed individuals and 19 controls were tested for serum HGF using ELISAs. Correlation was established between HGF concentration and disease severity.

RESULTS

Depressed individuals had significantly lower serum levels of HGF compared to controls (P < 0.0001). HGF concentration correlated with overall depressive behavior (P = 0.03) and specifically depression (P = 0.02), but not anxiety (P = 0.36).

DISCUSSION

These results suggest an association between HGF serum levels and clinically depressed individuals and demonstrate a correlation between severity of depression and HGF levels. Further studies of the predictive strength of HGF as a biomarker for depression may be warranted.

Cell delivery of Met docking site peptides inhibit angiogenesis and vascular tumor growth

Hepatocyte growth factor (HGF) and its receptor Met are responsible for a wide variety of cellular responses, both physiologically during embryo development and tissue homeostasis, and pathologically, particularly during tumor growth and dissemination. In cancer, Met can act as an oncogene on tumor cells, as well as a pro-angiogenic factor activating endothelial cells and inducing new vessel formation. Molecules interfering with Met activity could be valuable therapeutic agents. Here we have investigated the antiangiogenic properties of a synthetic peptide mimicking the docking site of the Met carboxyl-terminal tail, which was delivered into the cells by fusion with the internalization sequences from Antennapedia or HIV-Tat. We showed that these peptides inhibit ligand-dependent endothelial cell proliferation, motility, invasiveness and morphogenesis in vitro to an even greater extent and with much less toxicity than the Met inhibitor PHA-665752, which correlated with interference of HGF-dependent downstream signaling. In vivo, the peptides inhibited HGF-induced angiogenesis in the matrigel sponge assay and impaired xenograft tumor growth and vascularization in Kaposi's sarcoma. These data show that interference with the Met receptor intracellular sequence impairs HGF-induced angiogenesis, suggesting the use of antidocking site compounds as a therapeutic strategy to counteract angiogenesis in cancer as well as in other diseases.

Synthesis of Tc-99m labeled 1,2,3-triazole-4-yl c-met binding peptide as a potential c-met receptor kinase positive tumor imaging agent

The mesenchymal-epithelial transition factor (c-Met), which is related to tumor cell growth, angiogenesis and metastases, is known to be overexpressed in several tumor types. In this study, we synthesized technetium-99m labeled 1,2,3-triazole-4-yl c-Met binding peptide (cMBP) derivatives, prepared by solid phase peptide synthesis and the 'click-to-chelate' protocol for the introduction of tricarbonyl technetium-99m, as a potential c-Met receptor kinase positive tumor imaging agent, and evaluated their in vitro c-Met binding affinity, cellular uptake, and stability. The (99m)Tc labeled cMBP derivatives ([(99m)Tc(CO)(3)]12, [(99m)Tc(CO)(3)]13, and [(99m)Tc(CO)(3)]14) were prepared in 85-90% radiochemical yields. The cold surrogate cMBP derivatives, [Re(CO)(3)]12, [Re(CO)(3)]13, and [Re(CO)(3)]14, were shown to have high binding affinities (0.13 microM, 0.06 microM, and 0.16 microM, respectively) to a purified cMet/Fc chimeric recombinant protein. In addition, the in vitro cellular uptake and inhibition studies demonstrated the high specific binding of these (99m)Tc labeled cMBP derivatives ([(99m)Tc(CO)(3)]12-14) to c-Met receptor positive U87MG cells.

A hydrocellular foam dressing versus gauze: effects on the healing of rat excisional wounds

OBJECTIVE

Hydrocellular foam dressings are characterised by their ability to create a moist wound healing environment and absorb high amounts of exudate. In this study, we examined the effect of a hydrocellular foam dressing on the healing of rat excisional wounds.

METHOD

One full-thickness wound was made on the back of rats and wounds were treated with hydrocellular foam dressing or gauze dressing. To examine the histology of the wound, haematoxylin and eosin (HE) staining was performed. Gene expression of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), hepatocyte growth factor (HGF) and hypoxia inducible factor-1 alpha (HIF-1a) in granulation tissue was examined by real-time reverse transcription polymerase chain reaction (real-time RT-PCR). VEGF protein was measured by ELISA.

RESULTS

The hydrocellular foam dressing promoted formation of granulation tissue and significantly promoted wound closure. A scab formed on the surface of granulation tissue in the gauze-treated wounds, which disturbed epithelialisation. In addition, the expression of VEGF and mRNA was higher in the gauze-treated wounds.

CONCLUSION

These results supports the hypothesis that gauze encourages scab formation, which impairs epithelialisation and increases VEGF expression. In contrast, hydrocellular foam dressing accelerates epithelialisation and new vessel formation in granulation tissue.

Molecular mechanisms of resistance to tumour anti-angiogenic strategies

Tumour angiogenesis, described by Folkman in the early seventies, is an essential, complex, and dynamic process necessary for the growth of all solid tumours. Among the angiogenic factors secreted by the tumour cells, the Vascular Endothelial Growth Factor (VEGF) is one of the most important. Most types of human cancer cells express elevated levels of this proangiogenic factor and its receptors. New molecules, called anti-angiogenic, are developed to impair VEGF pathway and tumour vasculature. Despite important results, the clinical benefits of anti-VEGF therapy are relatively modest and usually measured in weeks or months. Why following anti-angiogenic therapy do some patients respond transiently and then why does tumour grow again and disease progress and which compensatory mechanisms could explain the anti-angiogenic treatment failure?

Selection criteria for c-Met-targeted therapies: emerging evidence for biomarkers

Extensive development of targeted therapies emphasize the critical need for biomarkers and major efforts have been engaged to identify screening, prognostic, stratification and therapy-monitoring markers. One of the challenges in translating preclinical studies into effective clinical therapies remains the accurate identification of a responsive subsets of patients. Studies on trastuzumab demonstrated that patient response could be specifically correlated with the amplification of the Her2 gene. However, for the EGF receptor, it has been more difficult to find the right stratification biomarker and recent data demonstrate that genetic alterations for the EGF receptor have to be considered. Taken together, these data underline the need for a deeper understanding of both targeted receptor and human disease to determine pathways that might be investigated during early clinical trials in order to define relevant biomarkers for patient selection. This article, dealing with the c-Met tyrosine kinase receptor, provides an overview of c-Met alterations observed in cancer and proposes approaches for stratification biomarker selection.

A novel small molecule Met inhibitor, PF2362376, exhibits biological activity against osteosarcoma

The receptor tyrosine kinase Met is dysregulated in several human cancers including osteosarcoma (OSA) in which overexpression is a negative prognostic indicator and enforced Met expression in normal osteoblasts leads to genomic instability and malignant transformation. Met is also known to be inappropriately expressed in canine OSA tumour samples and cell lines. The purpose of this study was to evaluate the potential utility of an orally bioavailable small molecule Met inhibitor, PF2362376, against canine OSA cell lines as a prelude to future clinical work. PF2362376 inhibited phosphorylation of Met, Gab-1, Erk and Akt, but not of Src or STAT3. Furthermore, PF2362376 inhibited proliferation of canine OSA cell lines and induced cell death at biologically achievable concentrations. Last, activities associated with Met signalling including migration, invasion, branching morphogenesis and colony formation in soft agar were blocked by PF2362376. These studies support the notion that Met is a relevant target for therapeutic intervention in OSA.

Characterization, expression and function of c-Met in canine spontaneous cancers

Aberrant expression of the proto-oncogene c-Met has been noted in a variety of human cancers. To better define the potential role of Met dysregulation in canine cancer, the canine Met, hepatocyte growth factor (HGF) and HGF activator were cloned. Inappropriate expression of Met was present in canine tumour cell lines derived from a wide variety of cancers. Furthermore, both HGF and HGF activator were also expressed in several of these cell lines, providing evidence of a possible autocrine loop of Met activation. Stimulation of tumour cell lines with recombinant human HGF induced Met autophosphorylation, as well as activation of the downstream signalling elements Gab-1, Akt and Erk1/2. Scattering of tumour cells and migration across a defect occurred in response to HGF stimulation. The Met inhibitor PHA665752 blocked both HGF-induced phosphorylation of canine Met and HGF-mediated cell cycling, scattering and migration. These studies provide evidence that Met dysregulation may play a role in the biology of canine cancer and lay the groundwork for future studies employing Met inhibitors.

Plasma level of soluble c-Met is tightly associated with the clinical risk of preeclampsia

OBJECTIVE

The objective of the study was to examine the relevance of the soluble form c-Met (sMet) with the clinical risk for severe preeclampsia.

STUDY DESIGN

This prospective case-control study was performed by using plasma derived from 44 preeclamptic and 51 uncomplicated pregnant women. Plasma concentration of sMet was measured with specific enzyme-linked immunosorbent assay, and the predictive values were determined based on the receiver-operating characteristic (ROC) curves analysis.

RESULTS

Plasma s-Met level in normal pregnant women changed in a gestation-dependent manner, peaking at weeks 19-24. In women with severe preeclampsia, the circulating sMet level was significantly lower than that in the gestational stage-matched controls during gestational weeks 15-30. The ROC curve analysis revealed a significant correlation between plasma sMet level and the risk of developing severe preeclampsia.

CONCLUSION

Plasma sMet could serve as a potential biomarker for predicting severe preeclampia at early second trimester of pregnancy.

Decreased Serum Hepatocyte Growth Factor (HGF) in Autistic Children with Severe Gastrointestinal Disease

Aim:

To assess serum Hepatocyte Growth Factor (HGF) levels in autistic children with severe gastrointestinal (GI) disease and to test the hypothesis that there is a relationship between GI pathology and HGF concentration.

Subjects and Methods:

Serum from 29 autistic children with chronic digestive disease (symptoms for a minimum of 6–12 months), most with ileo-colonic lymphoid nodular hyperplasia (LNH—markedly enlarged lymphoid nodules) and inflammation of the colorectum, small bowel and/or stomach), and 31 controls (11 age matched autistic children with no GI disease, 11 age matched non autistic children without GI disease and 9 age matched non autistic children with GI disease) were tested for HGF using ELISAs. HGF concentration of autistic children with GI disease was compared to GI disease severity.

Results:

Autistic children with GI disease had significantly lower serum levels of HGF compared to controls (autistic without GI disease; p = 0.0005, non autistic with no GI disease; p = 0.0001, and non autistic with GI disease; p = 0.001). Collectively, all autistic children had significantly lower HGF levels when compared to non autistic children (p < 0.0001). We did not find any relationship between severity of GI disease and HGF concentration in autistic children with GI disease.

Discussion:

These results suggest an association between HGF serum levels and the presence of GI disease in autistic children and explain a potential functional connection between the Met gene and autism. The concentration of serum HGF may be a useful biomarker for autistic children, especially those with severe GI disease.

Hepatocyte growth factor protects endothelial cells against gamma ray irradiation-induced damage

AIM

To investigate the effect of HGF on proliferation, apoptosis and migratory ability of human vascular endothelial cells against gamma ray irradiation.

METHODS

ECV304 cells derived from adult human umbilical vein endothelial cells (HUVEC) were irradiated with a single gamma ray dose of 20 Gy. Immunocytochemistry and Western blot analysis were used to detect c-Met protein expression and HGF/c-Met signal pathway. In the HGF-treated groups, ECV304 cells were incubated with HGF (20 or 40 ng/mL) 3 h prior to irradiation. At 48 h post-irradiation, the proliferation of ECV304 cells was measured by MTT assay, the apoptosis was assessed by flow cytometry, and the migratory ability of ECV304 cells was measured by transwell chamber assay.

RESULTS

c-Met protein is expressed in ECV304 cells and can be activated by HGF. Gamma ray irradiation inhibits proliferation and migration of ECV304 cells in a dose-dependent manner. HGF significantly promoted the proliferation of ECV304 cells, and flow cytometry revealed that HGF can inhibit apoptosis of ECV304 cells. Transwell chamber assay also showed that HGF increases migration activity of endothelial cells.

CONCLUSION

HGF may afford protection to vascular endothelial cells against gamma ray irradiation-induced damage.

Serum hepatocyte growth factor as a prognostic marker for stage II or III colorectal cancer patients

We previously reported that a combination of serum hepatocyte growth factor (HGF) and carcinoembryonic antigen (CEA) was useful for selecting early-stage colorectal cancer patients with aggressive disease. The aim of the present study was to determine whether serum HGF could provide CEA-independent prognostic information on patients undergoing surgery with curative intent. Serum samples were collected from 184 patients with colorectal cancer and 30 controls. Reverse-transcription polymerase chain reaction was used to detect HGF expression in colorectal cancer cell lines. Serum and tissue levels of HGF were measured by enzyme-linked immunosorbent assay. The serum HGF levels in colorectal cancer patients were compared with those in healthy controls, and we retrospectively assessed the association between serum HGF levels and clinicopathological findings and survival. Expression of HGF was significantly higher in colorectal cancer tissues compared with non-tumor tissues. The serum HGF levels were closely correlated with the HGF levels in cancer tissue. The mean serum HGF level in patients was significantly higher than that in controls, and significantly higher in patients with large tumor, lymph-node involvement and distant metastasis. According to the receiver operating characteristic (ROC) analysis, elevated serum HGF levels can predict patients with larger tumor, lymph-node and distant metastasis. Elevated serum HGF level demonstrated a significant association with poor survival, and was only an independent risk factor for poor survival in Stage II or/and III. Elevated serum HGF level is significantly associated with colorectal cancer development, lymph or distant invasive phenotypes and survival, especially in Stage II or III patients.

Hepatocyte growth factor induced up-regulations of VEGF through Egr-1 in hepatocellular carcinoma cells

The potential role of hepatocyte growth factor (HGF) in the regulation of angiogenesis factors in hepatoma cells is not widely appreciated. We investigated the role of HGF-induced activation of a transcription factor, Egr-1, in the expression of pro-angiogenic factors. Genes associated with angiogenesis induced by HGF were screened by using cDNA microarray technology in hepatocellular carcinoma cell lines, HepG2 and Hep3B. Expression levels of Egr-1, vascular endothelial growth factor (VEGF), and interleukin (IL)-8 were further confirmed by real time RT-PCR and Western blot analysis. Roles of Egr-1 in the levels of HGF-induced up-regulations of VEGF and IL-8 were measured by knockdown of Egr-1 with Egr-1 shRNA and chromatin immunoprecipitation assay. The levels of Egr-1, VEGF and IL-8 were up-regulated in cells treated with HGF. HGF-induced up-regulations of Egr-1, VEGF, and IL-8 were inhibited by the pretreatment with an MEK inhibitor, PD098059. HGF-induced up-regulation of VEGF and IL-8 were repressed by Egr-1 knockdown. HGF enhanced the binding activity of Egr-1 to the VEGF promoter in control cells, but not in the Egr-1-shRNA cells. No constitutive and inducible Egr-1 binding activities to the IL-8 promoter were observed in control and Egr-1-shRNA cells. Egr-1 knockdown reduced the luciferase activities increased by HGF not in the IL-8 promoter, but in the VEGF promoter. Egr-1 might play an important role in the up-regulation of VEGF and IL-8 induced by HGF and contribute to HGF-mediated angiogenesis, which might be promising targets for hepatocellular carcinoma therapy.

Differential inhibitor of Gbetagamma signaling to AKT and ERK derived from phosducin-like protein: effect on sphingosine 1-phosphate-induced endothelial cell migration and in vitro angiogenesis

Differential inhibitors of Gbetagamma-effector regions are required to dissect the biological contribution of specific Gbetagamma-initiated signaling pathways. Here, we characterize PhLP-M1-G149, a Gbetagamma-interacting construct derived from phosducin-like protein 1 (PhLP) as a differential inhibitor of Gbetagamma, which, in endothelial cells, prevented sphingosine 1-phosphate-induced phosphorylation of AKT, glycogen synthase kinase 3beta, cell migration, and tubulogenesis, while having no effect on ERK phosphorylation or hepatocyte growth factor-dependent responses. This construct attenuated the recruitment of phosphoinositide 3-kinase gamma (PI3Kgamma) to the plasma membrane and the signaling to AKT in response to Gbetagamma overexpression. In coimmunoprecipitation experiments, PhLP-M1-G149 interfered with the interaction between PI3Kgamma and Gbetagamma. Other PhLP-derived constructs interacted with Gbetagamma but were not effective inhibitors of Gbetagamma signaling to AKT or ERK. Our results indicate that PhLP-M1-G149 is a suitable tool to differentially modulate the Gbetagamma-initiated pathway linking this heterodimer to AKT, endothelial cell migration, and in vitro angiogenesis. It can be also useful to further characterize the molecular determinants of the Gbetagamma-PI3Kgamma interaction.

Immunopathogenesis of pelvic endometriosis: role of hepatocyte growth factor, macrophages and ovarian steroids

Endometriosis, a chronic disease characterized by endometrial tissue located outside the uterine cavity is associated with chronic pelvic pain and infertility. However, an in-depth understanding of the pathophysiology of endometriosis is still elusive. It is generally believed that besides ovarian steroid hormones, the growth of endometriosis can be regulated by innate immune system in pelvic microenvironment by their interaction with endometrial cells and immune cells. We conducted a series of studies in perspectives of pelvic inflammation that is triggered primarily by bacterial endotoxin (lipopolysaccharide) and is mediated by toll-like receptor 4 and showed their involvement in the development of pelvic endometriosis. As a cellular component of innate immune system, macrophages were found to play a central role in inducing pelvic inflammatory reaction. We further report here that peritoneal macrophages retain receptors encoding for estrogen and progesterone and ovarian steroids also participate in producing an inflammatory response in pelvic cavity and are involved in the growth of endometriosis either alone or in combination with hepatocyte growth factor (HGF). As a pleiotropic growth factor, HGF retains multifunctional role ometriosis. We describe here the individual and step-wise role of HGF, macrophages and ovarian steroid hormones and their orchestrated involvement in the immunopathogenesis of pelvic endometriosis.

The hepatocyte growth factor/c-Met signaling pathway as a therapeutic target to inhibit angiogenesis

Angiogenesis in tumors is driven by multiple growth factors that activate receptor tyrosine kinases. An important driving force of angiogenesis in solid tumors is signaling through vascular endothelial growth factor (VEGF) and its receptors (VEGFRs). Angiogenesis inhibitors that target this signaling pathway are now in widespread use for the treatment of cancer. However, when used alone, inhibitors of VEGF/VEGFR signaling do not destroy all blood vessels in tumors and do not slow the growth of most human cancers. VEGF/VEGFR signaling inhibitors are, therefore, used in combination with chemotherapeutic agents or radiation therapy. Additional targets for inhibiting angiogenesis would be useful for more efficacious treatment of cancer. One promising target is the signaling pathway of hepatocyte growth factor (HGF) and its receptor (HGFR, also known as c-Met), which plays important roles in angiogenesis and tumor growth. Inhibitors of this signaling pathway have been shown to inhibit angiogenesis in multiple in vitro and in vivo models. The HGF/c-Met signaling pathway is now recognized as a promising target in cancer by inhibiting angiogenesis, tumor growth, invasion, and metastasis.

Tube formation: an in vitro matrigel angiogenesis assay

Neovascularization plays a role in several pathological conditions, including tumor growth, arthritis, and choroidal neovascularization. Investigators from different fields can choose from several available angiogenesis assays according to their specific needs. This chapter describes an easy-to-perform assay that is based on the differentiation of endothelial cells and the formation of tube-like structures on an extracellular matrix, Matrigel. The assay can be used to screen compounds for angiogenic activity or to determine if it has an effect on angiogenesis, depending on the conditions chosen. It is a quick assay, easy to set up, and highly reproducible. It can be used to test one or two samples, or it can quickly be scaled up to screen hundreds of compounds. The flexibility that this assay provides makes it a good first choice to test if a compound or a series of compounds may play a role in angiogenesis.

Met gene copy number predicts the prognosis for completely resected non-small cell lung cancer

The Met oncogene encodes the tyrosine kinase receptor for hepatocyte growth factor (HGF). Uncontrolled activation of Met is oncogenic and has been implicated in the growth, invasion and metastasis in a variety of tumors. Several distinct mechanisms including amplification, translocation or mutation of Met may underlie uncontrolled Met activation. In several solid tumors, amplification and mutation of Met were reported to be associated with tumorigenesis, invasion and metastasis. The present study evaluated the amplification and mutation of Met in a large number of non-small cell lung cancer (NSCLC). Among 213 NSCLC patients, increased Met copy number was identified in 12 patients (5.6%) and associated with a worse prognosis (P = 0.0414). The mutation of Met in 534 NSCLC patients was also evaluated. In these patients there were no previously reported mutations within the juxtamembrane (JM) domain (R988C, T1010I, S1058P and G1085X). However, a somatic exon 14 deleting splice variant in 3 (1.7%) of 178 NSCLC samples was identified for which sequencing was performed. Met amplification and mutation were rare in Japanese NSCLC. However, the results support a critical role of Met gene dose in NSCLC, suggesting that Met may be a specific molecular therapeutic target in selected NSCLC patients with increased Met copy number.

Differences in the temporal expression of regulatory growth factors during choroidal neovascular development

Although the roles of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and hepatocyte growth factor (HGF) in pathologic neovascularization have been well characterized in certain tissues, their particular functions and expression patterns in choroidal neovascularization (CNV) have not been clearly established. After localized laser trauma to Bruch's membrane to induce CNV development, the temporal changes in mRNA and protein expression of these 3 cytokines were documented and compared histologically to areas of immunofluorescence, the proliferation of endothelial cells, neovascular development, and temporal changes in vascular permeability. Changes in mRNA and protein levels of bFGF and HGF occurred quickly and reached peak expression within hours. This activity corresponded in time to intense and localized immunofluorescence for these cytokines within the choriocapillaris within laser lesion sites. During this same initial time period, mRNA upregulation of VEGF occurred, primarily within the neural retina and this expression corresponded to intense immunolabeling of Müller cells immediately adjacent to the lesion sites. By 3 days after lasering, increased VEGF(164) protein expression was measurable, whereas early neovascular development histologically corresponded to HGF and bFGF mRNA expansion into the developing choroidal neovascular membrane (CNVM). At 7 days, CNV expansion, maturation, and increased vascular permeability corresponded to peak VEGF mRNA and protein expression and to immunofluorescence of the CNVM. Differences also occurred in the expression of precursor and activated isoforms of these cytokines in the retinal pigment epithelium/choroid as compared to those in the retina. These molecular and immunocytochemical results suggest that bFGF and HGF may be important as initial regulators neovascularization in this CNV model; whereas VEGF may be important during later phases of angiogenesis and neovascular hyperpermeability.

Hepatocyte growth factor inhibits VEGF-forkhead-dependent gene expression in endothelial cells

OBJECTIVE

Recently, we reported that the forkhead transcription factor, FKHR/FOXO1, is required for vascular endothelial growth factor (VEGF)-mediated upregulation of a number of genes in endothelial cells. Here, we tested the hypothesis that hepatocyte growth factor (HGF), a potent activator of PI3K-Akt in endothelial cells, is capable of depleting the nucleus of FKHR/FOXO1 and thus inhibiting VEGF induction of this class of genes.

METHODS AND RESULTS

Incubation of human coronary artery endothelial cells with HGF induced prolonged PI3K/Akt-dependent phosphorylation and nuclear exclusion of FKHR/FOXO1. HGF-mediated inhibition of FKHR/FOXO1 activity resulted in secondary attenuation of VEGF-induced expression of FKHR/FOXO1-dependent genes including vascular cell adhesion molecule-1, manganese superoxide dismutase, endothelial specific molecule-1, CBP/p300 interacting transactivator with ED-rich tail-2, bone morphogenetic protein-2, matrix metalloproteinase (MMP)-10, and MGC5618. At a functional level, preincubation of HGF resulted in inhibition of VEGF-induced vascular cell adhesion molecule (VCAM)-1-mediated monocyte adhesion to endothelial cells. HGF-mediated inhibition of VEGF-inducible VCAM-1 expression and monocyte adhesion was reversed by overexpression of constitutively active phosphorylation-resistant triple mutant (TM)-FKHR.

CONCLUSIONS

These findings suggest that physiological agonists of PI3K-Akt signaling pathway may modulate VEGF-FKHR/FOXO1-dependent gene expression in endothelial cells. The data underscore the importance of the "set point" of the endothelial cell when considering mechanisms of signal transduction.

Human dermal fibroblast subpopulations; differential interactions with vascular endothelial cells in coculture: nonsoluble factors in the extracellular matrix influence interactions

The superficial dermis of adult human skin contains a complex arcading microvasculature that provides nutrient support to the overlying epidermis. We propose that the unique subpopulations of dermal fibroblasts located in the superficial dermis contribute to the organization and maintenance of this elaborate microvasculature. This possibility was tested in a coculture system in which distinct subpopulations of adult human dermal fibroblasts were grown to form high-density lawns that were then seeded with human umbilical vein vascular endothelial cells (EC). The fibroblast subpopulation cultured specifically from the papillary dermis supported a robust array of highly branched tube-like structures. In contrast, fibroblasts cultured from the reticular dermis provided an anemic level of support for the formation of tube-like structures. These varied interactions with vascular EC were not due to the differential production of the potent pro-angiogenic factors vascular endothelial growth factor-A or fibroblast growth factor-2. Instead, the extracellular matrix and/or molecules bound to this matrix appeared to contain instructions that modulated these differential fibroblast-vascular EC interactions. One matrix-binding growth factor, hepatocyte growth factor/scatter factor, was identified that was both differentially expressed by papillary and reticular dermal fibroblasts and which was shown to be physiologically relevant in the coculture model. These studies highlight the importance of fibroblasts in supporting and maintaining vascular integrity. Furthermore, these studies have important implications for wound repair and may help to explain how fibroblasts contribute to the etiology of nonhealing wounds.

Prognostic significance of serum hepatocyte growth factor in clear cell renal cell carcinoma: comparison with serum vascular endothelial growth factor

No adequate serum predictive biomarker currently exists, which can identify the activity of renal cell carcinoma (RCC). We investigate the association of serum hepatocyte growth factor (HGF) and serum vascular endothelial growth factor (VEGF) levels with clinicopathologic parameters in untreated clear cell RCC patients. We measured serum levels of HGF and VEGF in 45 patients with untreated clear cell RCC and 45 healthy controls using an enzyme-linked immunosorbent assay (ELISA). Patients with clear cell RCC had significantly higher serum HGF and VEGF concentrations than healthy subjects: median, 1070.7 versus 728.3 pg/ml (p<0.0001) for HGF; and median, 397.5 versus 245.6 pg/ml (p=0.0003) for VEGF. We found a significant correlation between serum level of HGF and clinical stage and tumor grade. Survival of patients with high serum HGF (>1150 pg/ml) was significantly reduced compared to patients with low serum HGF concentrations (p=0.0044). In patients with nuclear grade 2 or high stage RCC, the higher serum HGF group exhibited significantly lower cause-specific survival (p=0.0087 and p< 0.05, respectively). No significant difference was observed between serum VEGF levels and cause-specific survival rate. Serum HGF might be a diagnostic and prognostic indicator in clear cell RCC, especially for patients with grade 2 or high stage RCC.

Simultaneous occurrence of infantile hemangioma and congenital melanocytic nevus: Coincidence or real association?

Both infantile hemangiomas (IH) and congenital melanocytic nevi (CMN) are common birthmarks that affect approximately 4% to 5% of infants and 1% of newborns, respectively. No previous association has been established between these birthmarks. We report a series of 6 patients who were remarkable for either the proximity or extent of anatomic involvement of their IH and CMN. Patient 1 had a large CMN in the area of her left eye and upper face in addition to a parotid IH. Likewise, patient 5 had a giant CMN on her back and a beard distribution IH. Patients 2, 3, and 4 were found to have small CMNs and localized IH in close anatomic proximity. Patient 6 was seen for a large left parietal scalp CMN with satellite nevi and multiple cutaneous hemangiomas. Although IH and CMN are common birthmarks, the clinical characteristics in these cases suggest a real, not coincidental association. Possible pathogenetic mechanisms to explain this association are discussed.

Multigenic control of skin tumour development in mice

Different inbred mouse strains vary greatly in their susceptibility to tumour development in a variety of tissues. Intraspecific and interspecific crosses can, therefore, be used to map the loci that control this predisposition. Crosses of Mus musculus with Mus spretus are highly resistant to tumour development in the skin, liver, lung and lymphoid system. M. spretus, therefore, has dominantly acting resistance loci, which we have attempted to map. More than 350 interspecific backcross mice were followed for 18 months to assess susceptibility to development of chemically induced papillomas and carcinomas. The results were analysed using a combination of MAPMAKER/QTL analysis and multiple regression analysis for the determination of linkage in multigenic quantitative traits. The results showed clearly that at least three genes on chromosomes 5 and 7 control resistance to tumour development. Importantly, some genes confer resistance to benign tumours but they have relatively little effect on malignant progression. This suggests the existence of different classes of benign tumours: those that are capable of tumour progression and those that have only a very low probability of becoming malignant. Identification of these genes will improve our understanding of mechanisms of carcinogenesis and may provide a novel route to the identification of "low-penetrance' human tumour susceptibility genes.

Semaphorin signaling in vascular and tumor biology

The neuropilins were originally characterized as cell membrane receptors that bind axon guidance factors belonging to the class-3 semaphorin subfamily. To transduce semaphorin signals, they form complexes with members of the plexin receptor family in which neuropilins serve as the ligand binding components and the plexins as the signal transducing components. The neuropilins were subsequently found to double as receptors for specific heparin binding splice forms of vascular endothelial growth factor (VEGF), and to be expressed on endothelial cells. This finding suggested that semaphorins may function as modulators of angiogenesis. It was recently found that several types of semaphorins such as semaphorin-3F function as inhibitors of angiogenesis while others, most notably semaphorin-4D, function as angiogenic factors. Furthermore, semaphorins such as semaphorin-3F and semaphorin-3B have been characterized as tumor suppressors and have been found to exert direct effects upon tumor cells. In this chapter we cover recent developments in this rapidly developing field of research.

Enhanced angiogenesis in grafted skins by laser-induced stress wave-assisted gene transfer of hepatocyte growth factor

Treatment to increase secretion of growth factors related to angiogenesis by gene transfection is a promising therapeutic solution for improving the outcome of tissue transplantation. We attempted to deliver a therapeutic vector construct carrying the human hepatocyte growth factor (hHGF) gene to skin grafts of rats using laser-induced stress waves (LISWs), with the objective of enhancing their adhesion. First we delivered the hHGF gene to rat native skin in vivo to determine the optimum gene transfer conditions. We then transferred the hHGF gene to excised rat skins, with which autografting was performed. We found that the density and uniformity of neovascularities were significantly enhanced in the grafted skins that were transfected using LISWs. These results suggest the efficacy of this method to improve the outcome of skin grafting. To our knowledge, this is the first experimental demonstration of a therapeutic efficacy based on LISW-mediated gene transfection. Since the present method can be applied not only to various types of tissues but also to bioengineered tissues, this technique has the potential to contribute to progress in transplantation medicine and future regenerative medicine.

HGF attenuates thrombin-induced endothelial permeability by Tiam1-mediated activation of the Rac pathway and by Tiam1/Rac-dependent inhibition of the Rho pathway

Reorganization of the endothelial cell (EC) cytoskeleton and cell adhesive complexes provides a structural basis for increased vascular permeability implicated in the pathogenesis of many diseases, including asthma, sepsis, and acute respiratory distress syndrome (ARDS). We have recently described the barrier-protective effects of hepatocyte growth factor (HGF) on the human pulmonary EC. In the present study, we explored the involvement of Rac-GTPase and Rac-specific nucleotide exchange factor Tiam1 in the mechanisms of EC barrier protection by HGF. HGF protected EC monolayers from thrombin-induced hyperpermeability, disruption of intercellular junctions, and formation of stress fibers and paracellular gaps by inhibiting thrombin-induced activation of Rho GTPase, Rho association with nucleotide exchange factor p115-RhoGEF, and myosin light chain phosphorylation, which was opposed by stimulation of Rac-dependent signaling. The pharmacological Rac inhibitor or silencing RNA (siRNA) based depletion of either Rac or Tiam1 significantly attenuated HGF-induced peripheral translocation of Rac effector cortactin, cortical actin ring formation, and EC barrier enhancement. Moreover, Tiam1 knockdown using the siRNA approach, attenuated the protective effect of HGF against thrombin-induced activation of Rho signaling, monolayer disruption, and EC hyperpermeability. This study demonstrates the Tiam1/Rac-dependent mechanism of HGF-induced EC barrier protection and provides novel mechanistic insights into regulation of EC permeability via dynamic interactions between Rho- and Tiam1/Rac-mediated pathways.

Vascular endothelial growth factor and angiopoietin are required for prostate regeneration

BACKGROUND

The regulation of the prostate size by androgens may be partly the result of androgen effects on the prostatic vasculature. We examined the effect of changes in androgen levels on the expression of a variety of angiogenic factors in the mouse prostate and determined if vascular endothelial growth factor (VEGF)-A and the angiopoietins are involved in the vascular response to androgens.

METHODS

Expression of angiogenic factors in prostate was quantitated using real-time PCR at different times after castration and after administration of testosterone to castrated mice. Angiopoietins were localized in prostate by immunohistochemistry and in situ hybridization. The roles of VEGF and the angiopoietins in regeneration of the prostate were examined in mice inoculated with cells expressing soluble VEGF receptor-2 or soluble Tie-2.

RESULTS

Castration resulted in a decrease in VEGF-A, VEGF-B, VEGF-C, placenta growth factor, FGF-2, and FGF-8 expression after 1 day. In contrast, VEGF-D mRNA levels increased. No changes in angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), hepatocyte growth factor, VEGF receptor-1, VEGF receptor-2, or tie-2 mRNA levels were observed. Administration of testosterone to castrated mice had the opposite effect on expression of these angiogenic factors. Ang-2 was expressed predominantly in prostate epithelial cells whereas Ang-1 was expressed in epithelium and smooth muscle. Inoculation of mice with cells expressing soluble VEGF receptor-2 or Tie-2 blocked the increase in vascular density normally observed after administration of testosterone to castrated mice. The soluble receptors also blocked the increase in prostate weight and proliferation of prostatic epithelial cells.

CONCLUSION

VEGF-A and angiopoietins are required for the vascular response to androgens and for the ability of the prostate to regenerate in response to androgens.

From Tpr-Met to Met, tumorigenesis and tubes

The receptor for hepatocyte growth factor (HGF)/scatter factor (SF), Met, controls a program of invasive epithelial growth through the coordination of cell proliferation and survival, cell migration and epithelial morphogenesis. This process is important during embryogenesis and for organ regeneration in the adult. However, when deregulated the HGF/SF-Met signaling axis contributes to tumorigenesis and metastasis. Studies on the oncogenic activation of the Met receptor have shed light on the molecular mechanisms underlying the oncogenic activation of receptor tyrosine kinase (RTKs). More than a decade ago, work on the Met related oncogene, Tpr-Met, revealed the mechanism for activation of RTK-derived oncogenes generated following chromosomal translocation. More recently, studies on the mechanisms of downregulation of the Met RTK highlight a role for loss of downregulation in RTK oncogenic activation.

Utilizing the activation mechanism of serine proteases to engineer hepatocyte growth factor into a Met antagonist

Hepatocyte growth factor (HGF), the ligand for the receptor tyrosine kinase Met, is secreted as single chain pro-HGF that lacks signaling activity. Pro-HGF acquires functional competence upon cleavage between R494 and V495, generating a disulfide-linked alpha/beta-heterodimer, where the beta-chain of HGF (HGF beta) has a serine protease fold that lacks enzymatic activity. We show that, like serine proteases, insertion of the newly formed N terminus in the beta-chain is critical for activity, here by allosterically stabilizing interactions with Met. The HGF beta crystal structure shows that V495 inserts into the "activation pocket" near the Met binding site where the positively charged N terminus forms a salt bridge with the negatively charged D672, and the V495 side chain has hydrophobic interactions with main- and side-chain residues. Full-length two-chain HGF mutants designed to interrupt these interactions (D672N, V495G, V495A, G498I, and G498V) displayed <10% activity in Met receptor phosphorylation, cell migration, and proliferation assays. Impaired signaling of full-length mutants correlated with >50-fold decreases in Met binding of the low-affinity HGF beta domain alone bearing the same mutations and further correlated with impaired N-terminal insertion. Because high-affinity binding resides in the HGF alpha-chain, full-length mutants maintained normal Met binding and efficiently inhibited HGF-mediated Met activation. Conversion of HGF from agonist to antagonist was achieved by as little as removal of two methyl groups (V495A) or a single charge (D672N). Thus, although serine proteases and HGF have quite distinct functions in proteolysis and Met signal transduction, respectively, they share a similar activation mechanism.

Pro-angiogenic cytokines and their role in tumor angiogenesis

The development of solid tumors depends upon an adequate supply of blood. This can be achieved by way of co-option of preexisting blood vessels and by the induction of angiogenesis. During the past 30 years, tumor angiogenesis had been found to play a crucial role in the progression of solid tumors. Tumor angiogenesis was found to be induced by a variety of pro-angiogenic cytokines of which the best characterized is vascular endothelial growth factor (VEGF). Indeed, the first FDA approved anti-angiogenic drug for the treatment of cancer is Avastin, a neutralizing antibody directed against VEGF. This review focuses on cytokines which have been reported to induce tumor angiogenesis.

Angiogenic activitiy of syndecan-binding laminin peptide AG73 (RKRLQVQLSIRT)

The AG73 peptide (RKRLQVQLSIRT, mouse laminin alpha 1 chain 2719-2730) promotes cell adhesion and tumor metastasis, and interacts with transmembrane syndecan proteoglycans. Here, we demonstrate AG73 peptide angiogenic activity using in vitro, ex vivo, and in vivo models. AG73 induced murine endothelial cell (SVEC4-10) tube formation on Cultrex Basement Membrane Extract (Cultrex BME) and stimulated sprouting of aortic rings. None of the homologous sequences from the laminin alpha2, alpha3, alpha4, or alpha5 chains was as active as AG73 in promoting sprouting formation. AG73 also mediated angiogenesis in the chick chorioallantonic membrane (CAM) assay. Using subcutaneously injected Cultrex BME supplemented with AG73, we observed a large angiogenic response. Furthermore, AG73-conjugated to a chitosan membrane promoted a strong angiogenic response in the CAM assay. These results indicate that the AG73 peptide is a potent syndecan-binding angiogenesis stimulator and may be useful for therapeutic application to treat ischemic injuries.

Change of E-cadherin by hepatocyte growth factor and effects on the prognosis of hypopharyngeal carcinoma

BACKGROUND

Hepatocyte growth factor (HGF) is known to induce scattering in various epithelial cells, and E-cadherin plays important roles in the maintenance of cell-cell adhesion. However, the mechanisms surrounding these actions are not fully understood. Therefore, we examined how HGF affects the expression and distribution of E-cadherin. In addition, we observed the relationship between prognosis and modulation of E-cadherin by HGF in hypopharyngeal carcinoma.

METHODS

Tumor tissues from 66 patients with hypopharyngeal squamous cell carcinoma were evaluated for the expression of HGF, its receptor (c-Met), and E-cadherin. Reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot test were performed on hypopharyngeal cancer tissues. The association and changes of E-cadherin with HGF treatment in a hypopharyngeal cancer cell line were investigated by RT-PCR, Western blot analysis, inhibition assay, immunofluorescence staining, and invasion assay.

RESULTS

E-cadherin expression was found in 87.9% of squamous cell carcinomas; these could be further classified as membranous type (46.9%) or nonmembranous type (53.1%). The expression of HGF in tumors with nonmembranous type E-cadherin expression was far higher than in tumors with membranous expression. Nonmembranous type E-cadherin expression correlated significantly with lymph node metastasis, distant metastasis, and recurrence (P < .05). HGF decreased the expression of E-cadherin and induced the translocation of E-cadherin to the cytoplasm. HGF and E-cadherin neutralizing antibody stimulated dispersion, and HGF significantly enhanced the invasion of hypopharyngeal cancer cells in a dose-dependent manner (P < .05).

CONCLUSIONS

These results suggest that HGF can modulate the expression and intracellular localization of E-cadherin in hypopharyngeal cancer cells. In addition, these results indicate that changes in E-cadherin by HGF can affect the prognosis of hypopharyngeal carcinoma.

A fusion protein of hepatocyte growth factor for immobilization to collagen

We describe here a fusion protein consisting of hepatocyte growth factor (HGF; an angiogenic factor) and a collagen-binding domain (CBD) polypeptide of fibronectin (FN). This fusion protein (CBD-HGF), produced by a baculovirus expression system, exhibited much stronger collagen binding activity than native HGF in the range of 0.4-6.4microg/ml. Its binding at the lowest concentration exceeded that of HGF at the highest concentration. In addition, the collagen-bound CBD-HGF promoted growth of endothelial cells (ECs) to a greater degree at least 4 days longer than HGF added to the culture medium; about 5-fold greater increase in cell number after 10 days. These findings suggest that the fused CBD moiety not only helped immobilize HGF on collagen but also helped stabilize the fusion molecule, resulting in prolonged activity. The angiogenic activity of CBD-HGF in animal tissues was examined by subcutaneously implanting collagen sponges containing bound CBD-HGF. Blood vessel formation in the sponges after 7 days was 4-6-fold extensive as compared to the control sponges without sample. Implanted sponges with native HGF did not show significant difference from control. These results indicate that CBD-HGF is suitable for in vitro culture of ECs, and that this fusion protein can be used to confer HGF activity on biomaterials for use in tissue engineering.

Inhibition of c-Met and prevention of spontaneous metastatic spreading by the 2-indolinone RPI-1

Hepatocyte growth factor (HGF) and its tyrosine kinase receptor Met play a pivotal role in the tumor metastatic phenotype and represent attractive therapeutic targets. We investigated the biochemical and biological effects of the tyrosine kinase inhibitor RPI-1 on the human lung cancer cell lines H460 and N592, which express constitutively active Met. RPI-1-treated cells showed down-regulation of Met activation and expression, inhibition of HGF/Met-dependent downstream signaling involving AKT, signal transducers and activators of transcription 3 and paxillin, as well as a reduced expression of the proangiogenic factors vascular endothelial growth factor and basic fibroblast growth factor. Cell growth in soft agar of H460 cells was strongly reduced in the presence of the drug. Furthermore, RPI-1 inhibited both spontaneous and HGF-induced motility/invasiveness of both H460 and human endothelial cells. Targeting of Met signaling by alternative methods (Met small interfering RNA and anti-phosphorylated Met antibody intracellular transfer) produced comparable biochemical and biological effects. Using the spontaneously metastasizing lung carcinoma xenograft H460, daily oral treatment with well-tolerated doses of RPI-1 produced a significant reduction of spontaneous lung metastases (-75%; P < 0.001, compared with control mice). In addition, a significant inhibition of angiogenesis in primary s.c. tumors of treated mice was observed, possibly contributing to limit the development of metastases. The results provide preclinical evidence in support of Met targeting pharmacologic approach as a new option for the control of tumor metastatic dissemination.

Inhibitory effect of c-Met mutants on the formation of branching tubules by a porcine aortic endothelial cell line

The association of hepatocyte growth factor (HGF) with its high-affinity receptor (c-Met) has been shown to induce mitogenesis, motogenesis and morphogenesis in a variety of cell types. Various point mutations in c-Met have been identified in hereditary and sporadic papillary renal carcinomas as well as in other carcinomas. In the present study, we examined the effects of c-Met point mutations on the morphology of a porcine aortic endothelial (PAE) cell line. When cultured in three-dimensional collagen gel, PAE cells formed branching tubule structures, and HGF treatment caused breakdown of the structures and induced a scattered morphology. The exogenous expression of c-Met point mutants inhibited the formation of tubules. HGF treatment induced the formation of tubules by PAE cells expressing some c-Met mutants, but it induced the scattering of PAE cells expressing other c-Met mutants. The presence of a low concentration of a mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK) inhibitor cancelled the inhibitory effect of the c-Met point mutations on the formation of tubules. These results suggest that c-Met point mutations affect the extracellular signal-regulated kinase (ERK) signaling required for the formation of tubules by PAE cells, and HGF binding changes the conformation of c-Met mutants, leading to the different signals required for formation of tubules and cell scattering.

Blockage of HGF/c-Met system by gene therapy (adenovirus-mediated NK4 gene) suppresses hepatocellular carcinoma in mice

BACKGROUND/AIMS

Hepatocyte growth factor promotes cancer development through cell motility-promoting and angiogenic effects. NK4, a fragment of hepatocyte growth factor, acts as its receptor antagonist. We assessed effects of NK4 gene therapy against human hepatocellular carcinoma cells (HUH7) transplanted into mice.

METHODS

NK4 gene transduction was mediated by adenovirus (AdCMV.NK4). LacZ expression adenovirus (AdCMV.LacZ) was used as a control. NK4 effects on HUH7 cells first were studied in vitro. Subcutaneous HUH7 tumors established in athymic nude mice were injected with AdCMV.NK4 (n=6) or AdCMV.Lacz (n=6). Finally, after HUH7 cells were injected into the portal vein in mice with severe combined immunodeficiency to establish hepatic tumors, mice systemically were injected with AdCMV.NK4 (n=6) or AdCMV.LacZ (n=6).

RESULTS

NK4 inhibited hepatocyte growth factor-induced phosphorylation of c-Met in HUH7 cells. Invasion and migration of HUH7 cells were inhibited by NK4 transfection, which also suppressed growth of transplanted subcutaneous and liver tumors (p<0.001, p<0.01 respectively), and improved mouse survival (p<0.05). Angiogenesis assessed by small vessel density was significantly decreased in the NK4-treated group.

CONCLUSIONS

NK4 inhibited tumor cell motility and angiogenesis, greatly suppressing growth of HUH7 tumors transplanted into mouse liver. NK4 gene therapy thus showed apparent promise for treatment of hepatocellular carcinoma.

c-jun amino-terminal kinase and mitogen activated protein kinase 1/2 mediate hepatocyte growth factor-induced migration of brain endothelial cells

Hepatocyte growth factor (HGF) influences several components of the angiogenic response, including endothelial cell migration. While recent studies indicate a crucial role of HGF in brain angiogenesis, the signaling pathways that regulate brain endothelial cell migration by HGF remain uncharacterized. Herein, we report that HGF stimulated human brain microvascular endothelial cell (HBMEC) migration in a dose- and time-dependent manner. Challenge of HBMECs with HGF activated the c-jun amino-terminal kinase (JNK), increased phosphorylation of the proline-rich tyrosine kinase 2 (Pyk-2) at Tyr(402) and activated c-Src. Inhibition of JNK by SP600125 or expression of a dominant negative JNK1 construct abrogated the migratory response of HBMECs to HGF. Treatment of HBMECs with the Src inhibitor PP2 markedly decreased HGF-stimulated JNK activation and migration to HGF. Moreover, expression of a mutant Pyk-2 construct prevented HGF-induced Pyk-2 phosphorylation at Tyr(402) and stimulation of HBMEC migration. Next, we examined activation of the extracellular signal regulated kinase (ERK) pathway. Stimulation of HBMECs by HGF led to rapid activation of ERK1/2, phosphorylation of Raf-1 at Ser(338) and Tyr(340/341) and MEK1/2 at Ser(222). Moreover, inhibition of ERK activation by UO126 and PD98059 markedly decreased HGF-stimulated HBMEC migration. HGF also activated AKT, while inhibition of AKT by LY294002 induced a modest decrease of HGF-induced HBMEC migration. These results highlight a model whereby JNK and ERK play a critical role in regulation of brain endothelial cell migration by HGF.

Effects of hepatocyte growth factor and platelet-derived growth factor on the repair of meniscal defects in vitro

Injuries to the avascular region of the meniscus occur frequently and may be difficult to repair. This study was designed to determine whether growth factors could diffuse from a collagen sponge or a collagen gel into meniscal tissue and stimulate healing of defects using an in vitro model. The diffusion of platelet-derived growth factor (PDGF) from the collagen carriers into the medium was rapid with approximately 50% being released from the collagen sponge within the first hour. After 5 d of incubation, 8% of the PDGF was present in the meniscus, 11% in the collagen sponge, and 62% had been released into the medium. Similar results were obtained when a collagen gel was used as a carrier. Histological evaluation of the meniscal explants after 2 wk in culture revealed extensive proteoglycan staining in the areas surrounding defects treated with either hepatocyte growth factor (HGF) or PDGF compared with controls without growth factor. The HGF-PDGF treatment resulted in alignment and migration of meniscal cells toward the defect, which was not observed in untreated controls. At 3-7 d, increased number of cells were observed in defects treated with collagen gels (but not the sponge) with PDGF-HGF. At 4 wk, combined HGF-PDGF treatment resulted in the formation of tissue with birefringence by polarized microscopy, suggestive of organized collagen. The data suggest that use of specific PDGF-HGF may enhance the repair of meniscal injuries.

The molecular and clinical impact of hepatocyte growth factor, its receptor, activators, and inhibitors in wound healing

Wound healing involves a number of cellular and molecular events, many of which are controlled by soluble growth factors. In the process of healing, hepatocyte growth factor, a cytokine known to act as mitogen, motogen, and morphogen, has been postulated to play multiple roles during several stages of this complex biological process. Produced primarily by stromal fibroblasts, hepatocyte growth factor regulates angiogenesis, vascular permeability, cell migration, matrix deposition and degradation, and other biological processes. The current article discusses recent progress in understanding the multiple roles played by this growth factor in tissue repair.