Foretinib, a c-MET receptor tyrosine kinase inhibitor, tackles multidrug resistance in cancer cells by inhibiting ABCB1 and ABCG2 transporters.

BACKGROUND: ABC transporter-mediated multidrug resistance (MDR) remains a major obstacle for cancer pharmacological treatment. Some tyrosine kinase inhibitors (TKIs) have been shown to reverse MDR. The present study was designed to evaluate for the first time whether foretinib, a multitargeted TKI, can circumvent ABCB1 and ABCG2-mediated MDR in treatment-resistant cancer models. METHODS: Accumulation of fluorescent substrates of ABCB1 and ABCG2 in ABCB1-overexpressing MES-SA/DX5 and ABCG2-overexpressing MCF-7/MX and their parenteral cells was evaluated by flow cytometry. The growth inhibitory activity of single and combination therapy of foretinib and chemotherapeutic drugs on MDR cells was examined by MTT assay. Analysis of combined interaction effects was performed using CalcuSyn software. RESULTS: It was firstly proved that foretinib increased the intracellular accumulation of rhodamine 123 and mitoxantrone in MES-SA/DX5 and MCF-7/MX cancer cells, with accumulation ratios of 12 and 2.2 at 25 µM concentration, respectively. However, it did not affect the accumulation of fluorescent substrates in the parental cells. Moreover, foretinib synergistically improved the cytotoxic effects of doxorubicin and mitoxantrone. The means of combination index (CI) values at fraction affected (Fa) values of 0.5, 0.75, and 0.9 were 0.64 ± 0.08 and 0.47 ± 0.09, in MES-SA/DX5 and MCF-7/MX cancer cells, respectively. In silico analysis also suggested that the drug-binding domain of ABCB1 and ABCG2 transporters could be considered as potential target for foretinib. CONCLUSION: Overall, our results suggest that foretinib can target MDR-linked ABCB1 and ABCG2 transporters in clinical cancer therapy.

Hepatocyte growth factor mimetic confers protection from aminoglycoside-induced hair cell death in vitro.

Loss of sensory hair cells from exposure to certain licit drugs, such as aminoglycoside antibiotics, can result in permanent hearing damage. Exogenous application of the neurotrophic molecule hepatocyte growth factor (HGF) promotes neuronal cell survival in a variety of contexts, including protecting hair cells from aminoglycoside ototoxicity. HGF itself is not an ideal therapeutic due to a short half-life and limited blood-brain barrier permeability. MM-201 is a chemically stable, blood-brain barrier permeable, synthetic HGF mimetic that serves as a functional ligand to activate the HGF receptor and its downstream signaling cascade. We previously demonstrated that MM-201 robustly protects zebrafish lateral line hair cells from aminoglycoside ototoxicity. Here, we examined the ability of MM-201 to protect mammalian sensory hair cells from aminoglycoside damage to further evaluate MM-201's clinical potential. We found that MM-201 exhibited dose-dependent protection from neomycin and gentamicin ototoxicity in mature mouse utricular explants. MM-201's protection was reduced following inhibition of mTOR, a downstream target of HGF receptor activation, implicating the activation of endogenous intracellular substrates by MM-201 as critical for the observed protection. We then asked if MM-201 altered the bactericidal properties of aminoglycosides. Using either plate or liquid growth assays we found that MM-201 did not alter the bactericidal efficacy of aminoglycoside antibiotics at therapeutically relevant concentrations. We therefore assessed the protective capacity of MM-201 in an in vivo mouse model of kanamycin ototoxicity. In contrast to our in vitro data, MM-201 did not attenuate kanamycin ototoxicity in vivo. Further, we found that MM-201 was ototoxic to mice across the dose range tested here. These data suggest species- and tissue-specific differences in otoprotective capacity. Next generation HGF mimetics are in clinical trials for neurodegenerative diseases and show excellent safety profiles, but neither preclinical studies nor clinical trials have examined hearing loss as a potential consequence of pharmaceutical HGF activation. Further research is needed to determine the consequences of systemic MM-201 application on the auditory system.

A novel agonist for the HGF receptor MET promotes differentiation of human pluripotent stem cells into hepatocyte-like cells.

Hepatocyte growth factor (HGF) is the natural ligand of the MET receptor tyrosine kinase. This ligand-receptor couple is essential for the maturation process of hepatocytes. Previously, the rational design of a synthetic protein based on the assembly of two K1 domains from HGF led to the production of a potent and stable MET receptor agonist. In this study, we compared the effects of K1K1 with HGF during the differentiation of hepatocyte progenitors derived from human induced pluripotent stem cells (hiPSCs). In vitro, K1K1, in the range of 20 to 200 nM, successfully substituted for HGF and efficiently activated ERK downstream signaling. Analysis of the levels of hepatocyte markers showed typical liver mRNA and protein expression (HNF4α, albumin, alpha-fetoprotein, CYP3A4) and phenotypes. Although full maturation was not achieved, the results suggest that K1K1 is an attractive candidate MET agonist suitable for replacing complex and expensive HGF treatments to induce hepatic differentiation of hiPSCs.

Neutrophilic HGF-MET Signalling Exacerbates Intestinal Inflammation.

BACKGROUND AND AIMS: Ulcerative colitis [UC] is associated with excessive neutrophil infiltration and collateral tissue damage, but the link is not yet completely understood. Since c-MET receptor tyrosine kinase [MET] is required for neutrophil chemoattraction and cytotoxicity in response to its ligand hepatocyte growth factor [HGF], we aimed to identify the function of HGF-MET signalling in neutrophils in UC patients and in mice during intestinal inflammation. METHODS: Serum and colonic biopsies from healthy controls and UC patients with active [Mayo endoscopic subscore 2-3] and inactive [Mayo endoscopic subscore 0-1] disease were collected to assess the level of serum and colonic HGF. Disease progression and immune cell infiltration were assessed during dextran sodium sulphate [DSS] colitis in wild-type and MRP8-Cre MET-LoxP mice. RESULTS: Increased mucosal HGF expression was detected in patients with active UC, and in mice during the inflammatory phase of DSS colitis. Similarly, serum HGF was significantly increased in active UC patients and positively correlated with C-reactive protein and blood neutrophil counts. Flow cytometric analysis also demonstrated an upregulation of colonic MET+ neutrophils during DSS colitis. Genetic ablation of MET in neutrophils reduced the severity of DSS-induced colitis. Concomitantly, there was a decreased number of TH17 cells, which could be due to a decreased production of IL-1ß by MET-deficient neutrophils. CONCLUSIONS: These data highlight the central role of neutrophilic HGF-MET signalling in exacerbating damage during intestinal inflammation. Hence, selective blockade of this pathway in neutrophils could be considered as a novel therapeutic approach in UC.

Orlistat delays hepatocarcinogenesis in mice with hepatic co-activation of AKT and c-Met.

Orlistat (Xenical™), a US Food and Drug Administration (FDA)-approved anti-obesity drug, shows efficacy against multiple tumor types, including hepatocellular carcinoma (HCC), due to its ability to inhibit fatty acid synthase (FASN) activity. However, whether orlistat affects hepatocellular malignant transformation during hepatocarcinogenesis in vivo is unknown. This study assessed the antisteatotic and antitumorigenic efficacy of orlistat in a rapid HCC FVB/N mouse model established via hydrodynamic transfection of activated forms of AKT and c-Met proto-oncogenes. Human hepatoma cell lines were used for mechanical validation in vitro. Hematoxylin and eosin staining, immunohistochemistry, and immunoblotting were applied for the mechanistic investigation. The results revealed that when orlistat was administered in the early stage of AKT/c-Met-triggered hepatocarcinogenesis, it resulted in the elimination of hepatic tumor burden. Mechanistically, orlistat efficiently elevated PTEN expression and suppressed AKT/SREBP1/FASN signaling both in vivo and in vitro, impairing AKT/c-Met-driven de novo lipogenesis and aberrant proliferation. Altogether, this study demonstrates the antilipogenic and antiproliferative efficacy of orlistat in hepatocarcinogenesis, suggesting that orlistat may be beneficial for the treatment of HCC, especially in NAFLD-related HCCs featuring activated AKT/mTOR cascade and increased lipogenesis in livers.

Measurement of Serum and Hepatic Eicosanoids by Liquid Chromatography Tandem-Mass Spectrometry (LC-MS/MS) in a Mouse Model of Hepatocellular Carcinoma (HCC) with Delivery of c-Met and Activated ß-Catenin by Hepatocyte Hydrodynamic Injection.

BACKGROUND Most forms of cancer, including hepatocellular carcinoma (HCC), are associated with varying degrees of chronic inflammation. The association between the expression of eicosanoids, which are bioactive lipid mediators of inflammation, and HCC remains unknown. The aim of this study was to measure serum and hepatic eicosanoids in a mouse model of HCC with the delivery of c-Met and activated b-catenin by hepatocyte hydrodynamic injection. MATERIAL AND METHODS The HCC mouse model, and normal control mice, were used in this study with co-delivery of human c-Met combined with activated ß-catenin into hepatocytes through hydrodynamic injection. Liquid chromatography tandem-mass spectrometry (LC-MS/MS) analysis was used to measure serum and hepatic eicosanoid levels. RESULTS The combined activation of c-Met and ß-catenin was induced in the HCC mouse model. LC-MS/MS showed that a total of 13 eicosanoids in serum and 12 eicosanoids in liver tissue were significantly increased in the HCC mice, when compared with control mice. CONCLUSIONS In a mouse model of HCC, co-activation of the c-Met and ß-catenin signaling pathway resulted in increased levels of serum and hepatic eicosanoids.

Cerebral hemorrhage therapy by targeting VEGF and HGF in a preclinical trial in rats.

Cerebral hemorrhage is the most common type of human cerebrovascular disease and frequently causes paralysis, vegetative state and mortality. The modulatory actions of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) are vital in the human nervous system. The present study investigated the association between cerebral hemorrhage and the expression of VEGF and HGF in a rat model of cerebral hemorrhage. The therapeutic potential of cerebral hemorrhage was also evaluated using targeted drugs for VEGF and HGF in the cerebral hemorrhage rat model. Behavioral and preclinical changes and the survival rates of rats were assessed after treatment with VEGF receptor (VEGFR) and HGF receptor (HGFR). The results of Tarlov scores demonstrated that movement of limbs and coordination when walking were significantly improved in moderate and severe hemorrhage lesions in the VEGFR plus HGFR­treated group and mainly alleviated in primary hemorrhage lesions compared with rats in the single VEGFR or HGFR­treated groups and the control group (**P<0.01). Decreasing expression levels of VEGF and HGF were observed in the neural tissue of animals treated with VEGFR plus HGFR compared with the control group (**P<0.01). These preclinical observations indicated that VEGF and HGF serve a function in the pathological injury and repair of cerebral tissue in rats with cerebral hemorrhages. The therapeutic benefits of VEGFR plus HGFR suggested that VEGFR plus HGFR may be candidate drugs for cerebral hemorrhage, and thus offer a promising treatment for clinicians and doctors.

Tumor and circulating biomarkers in patients with second-line hepatocellular carcinoma from the randomized phase II study with tivantinib.

ARQ 197-215 was a randomized placebo-controlled phase II study testing the MET inhibitor tivantinib in second-line hepatocellular carcinoma (HCC) patients. It identified tumor MET as a key biomarker in HCC.Aim of this research was to study the prognostic and predictive value of tumor (MET, the receptor tyrosine kinase encoded by the homonymous MNNG-HOS transforming gene) and circulating (MET, hepatocyte growth factor [HGF], alpha-fetoprotein [AFP], vascular endothelial growth factor [VEGF]) biomarkers in second-line HCC. Tumor MET-High status was centrally assessed by immunohistochemistry. Circulating biomarkers were centrally analyzed on serum samples collected at baseline and every 4-8 weeks, using medians as cut-off to determine High/Low status. Tumor MET, tested in 77 patients, was more frequently High after (82%) versus before (40%) sorafenib. A significant interaction (p = 0.04) between tivantinib and baseline tumor MET in terms of survival was observed. Baseline circulating MET and HGF (102 patients) High status correlated with shorter survival (HR 0.61, p = 0.03, and HR 0.60, p = 0.02, respectively), while the association between AFP (104 patients) or VEGF (103 patients) status and survival was non-significant. CONCLUSIONS: Tumor MET levels were higher in patients treated with sorafenib. Circulating biomarkers such as MET and HGF may be prognostic in second-line HCC. These results need to be confirmed in larger randomized clinical trials.

Hepatocyte Growth Factor and MET Support Mouse Enteric Nervous System Development, the Peristaltic Response, and Intestinal Epithelial Proliferation in Response to Injury.

Factors providing trophic support to diverse enteric neuron subtypes remain poorly understood. We tested the hypothesis that hepatocyte growth factor (HGF) and the HGF receptor MET might support some types of enteric neurons. HGF and MET are expressed in fetal and adult enteric nervous system. In vitro, HGF increased enteric neuron differentiation and neurite length, but only if vanishingly small amounts (1 pg/ml) of glial cell line-derived neurotrophic factor were included in culture media. HGF effects were blocked by phosphatidylinositol-3 kinase inhibitor and by MET-blocking antibody. Both of these inhibitors and MEK inhibition reduced neurite length. In adult mice, MET was restricted to a subset of calcitonin gene-related peptide-immunoreactive (IR) myenteric plexus neurons thought to be intrinsic primary afferent neurons (IPANs). Conditional MET kinase domain inactivation (Met(fl/fl); Wnt1Cre+) caused a dramatic loss of myenteric plexus MET-IR neurites and 1-1'-dioctodecyl-3,3,3',3'-tetramethylindocarbocyamine perchlorate (DiI) labeling suggested reduced MET-IR neurite length. In vitro, Met(fl/fl); Wnt1Cre+ mouse bowel had markedly reduced peristalsis in response to mucosal deformation, but normal response to radial muscle stretch. However, whole-bowel transit, small-bowel transit, and colonic-bead expulsion were normal in Met(fl/fl); Wnt1Cre+ mice. Finally, Met(fl/fl); Wnt1Cre+ mice had more bowel injury and reduced epithelial cell proliferation compared with WT animals after dextran sodium sulfate treatment. These results suggest that HGF/MET signaling is important for development and function of a subset IPANs and that these cells regulate intestinal motility and epithelial cell proliferation in response to bowel injury. SIGNIFICANCE STATEMENT: The enteric nervous system has many neuronal subtypes that coordinate and control intestinal activity. Trophic factors that support these neuron types and enhance neurite growth after fetal development are not well understood. We show that a subset of adult calcitonin gene-related peptide (CGRP)-expressing myenteric neurons produce MET, the receptor for hepatocyte growth factor, and that loss of MET activity affects peristalsis in response to mucosal stroking, reduces MET-immunoreactive neurites, and increases susceptibility to dextran sodium sulfate-induced bowel injury. These observations may be relevant for understanding and treating intestinal motility disorders and also suggest that enhancing the activity of MET-expressing CGRP neurons might be a useful strategy to reduce bowel inflammation.

Amplification of the MET receptor drives resistance to anti-EGFR therapies in colorectal cancer.

EGF receptor (EGFR)-targeted monoclonal antibodies are effective in a subset of metastatic colorectal cancers. Inevitably, all patients develop resistance, which occurs through emergence of KRAS mutations in approximately 50% of the cases. We show that amplification of the MET proto-oncogene is associated with acquired resistance in tumors that do not develop KRAS mutations during anti-EGFR therapy. Amplification of the MET locus was present in circulating tumor DNA before relapse was clinically evident. Functional studies show that MET activation confers resistance to anti-EGFR therapy both in vitro and in vivo. Notably, in patient-derived colorectal cancer xenografts, MET amplification correlated with resistance to EGFR blockade, which could be overcome by MET kinase inhibitors. These results highlight the role of MET in mediating primary and secondary resistance to anti-EGFR therapies in colorectal cancer and encourage the use of MET inhibitors in patients displaying resistance as a result of MET amplification.

C-MET as a new therapeutic target for the development of novel anticancer drugs

MET is a tyrosine kinase receptor that, upon binding of its natural ligand, the hepatocyte growth factor (HGF), is phosphorylated and subsequently activates different signalling pathways involved in proliferation, motility, migration and invasion. MET has been found to be aberrantly activated in human cancer via mutation, amplification or protein overexpression. MET expression and activation have been associated with prognosis in a number of tumour types and predict response to MET inhibitors in preclinical models. Here we review the HGF/MET signalling pathway, its role in human cancer and the different inhibitory strategies that have been developed for therapeutic use (AU)

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Tissue factor mediates the HGF/Met-induced anti-apoptotic pathway in DAOY medulloblastoma cells.

The classical treatment scheme for medulloblastoma (MB) is based on a tri-therapy approach consisting of surgical tumor resection, craniospinal axis radiation and chemotherapy. With current treatments relying mainly on non-specific cytotoxic therapy, a better understanding of the mechanisms underlying resistance to these treatments is important in order to improve their effectiveness. In this study, we report that stimulation of DAOY with HGF resulted in the protection of these cells against etoposide-induced apoptosis, this anti-apoptotic effect being correlated with an increase in the expression of tissue factor (TF), the initiator of the extrinsic pathway of coagulation. HGF-mediated protection from apoptosis was abolished by a c-Met inhibitor as well as by siRNA-mediated reduction of TF levels, implying a central role of Met-dependent induction of TF expression in this process. Accordingly, stimulation of DAOY with FVIIa, the physiological ligand of TF, also resulted in a significant protection from etoposide-mediated cytotoxicity. Overall, our results suggest the participation of the haemostatic system to drug resistance in MB and may thus provide novel therapeutic approaches for the treatment of these tumors.

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.

C-Met antisense oligodeoxynucleotide inhibits growth of glioma cells.

BACKGROUND: C-Met, a receptor tyrosine kinase, and its ligand, hepatocyte growth factor, are critical in cellular proliferation, motility, and invasion and are known to be overexpressed in gliomas. The aim of our study was therefore to investigate the effect of transfected caroboxyfluorescein-5-succimidyl ester (FAM)-labeled c-Met antisense oligonucleotide (ASODN) on growth of glioma cells. METHODS: Conjugated FAM-labeled c-Met ASODN was encapsulated by LIPOFECTAMINE PLUS Reagent and then added into the human glioma cell line U251. Cultured cells were divided into 5 groups: control group, 500 nmol/L nonsense oligonucleotide (NSODN) group, 250 nmol/L ASODN group, 500 nmol/L ASODN group, and 750 nmol/L ASODN group. The intracellular distribution of c-Met ASODN was observed with fluorescence microscopy; cell growth was detected by methyl thiazole tetrazolium assay. The apoptosis of U251 cells was also examined with a flow cytometer. Semiquantitative reverse transcriptase polymerase chain reaction and Western blot examinations were carried for expression of c-Met messenger RNA (mRNA) and protein. RESULTS: The blue fluorescence was seen in the cytoplast and nuclei of cells of FAM-labeled c-Met ASODN groups with fluorescence microscopy after the cells were treated with FAM-labeled c-Met ASODN-LIPOFECTAMINE PLUS Reagent complex for 3 hours. Antisense (AS) oligonucleotide caused a statistically significant reduction of cell viability (P < .05), whereas NSODN had no such changes. The cell growth was also significantly inhibited by ASODN (P < .05). After transfection, 250, 500, and 750 nmol/L ASODN induced significant apoptotic response, about 4.67% +/- 2.86%, 8.65% +/- 3.18%, and 12.76% +/- 3.15% for 24 hours (P < .05) and 7.79% +/- 1.92%, 11.43% +/- 1.54%, and 15.78% +/- 1.86% for 48 hours (P < .01), respectively. However, 500 nmol/L NSODN did not induce any significant apoptotic response until 48 hours after transfection (P > .05). A significant loss of c-Met mRNA was presented in ASODN-treated cells, and this was not seen in treatment with NSODN. Protein level was significantly decreased 48 hours after c-Met ASODN transfected. CONCLUSIONS: Antisense oligonucleotide targeting c-Met can be identified as a most potent AS compound, which can inhibit cell growth and induce cell apoptosis. This provides evidence that c-Met plays a role in tumor progression of glioma by acting as an oncogene and suggests that c-Met ASODN may provide a novel approach to therapy for human glioma.

The SH2-domian-containing inositol 5-phosphatase (SHIP)-2 binds to c-Met directly via tyrosine residue 1356 and involves hepatocyte growth factor (HGF)-induced lamellipodium formation, cell scattering and cell spreading.

Recently, evidence has been accumulating that inositol and phosphatidylinositol polyphosphate play important roles in a variety of signal transduction systems including membrane traffic, actin cytoskeleton rearrangement and cell motility. In this paper, we show for the first time that the SH2-domain-containing inositol 5-phosphatase (SHIP)-2 binds directly to the hepatocyte growth factor (HGF/SF) receptor, c-Met, via phosphotyrosine 1356. HGF induces the breakdown of cell junctions and the dispersion of colonies of epithelial cells including MDCK cells. Whereas only few lamellipodia are observed in MDCK cells 2 min after stimulation with HGF, both SHIP-2- and SHIP-1-overexpressing cells form large, broad lamellipodia. The number of lamellipodia is 2-4-fold greater than that of mock-transfected MDCK cells in the same time period and SHIP is found to colocalize with actin at the leading edge. Furthermore, overexpression of a catalytic inactive mutant of SHIP-2 suppresses HGF-potentiated cell scattering and cell spreading, although these mutant-expressing cells form enhanced number of lamellipodia 2 min after HGF stimulation. Interestingly, cells expressing a mutant lacking the proline-rich domain of SHIP-2 at the C-terminal form few lamellipodia, but still spread and scatter upon stimulation with HGF at a reduced rate. These data suggest that phosphatase activity is required for HGF-mediated cell spreading and scattering but not for alteration of lamellipodium formation, while the proline-rich region influences lamellipodium formation. Furthermore, treatment with 10 microM of phosphatidylinositol 3 (PI3) kinase inhibitor, LY294002, abrogates HGF-induced cell scattering of SHIP-2-overexpressing cells but not parental HEK293 cells, suggesting that a balance between PI3 kinase and SHIP is important for cell motility.

Targeting the HGF/SF receptor c-met using a hammerhead ribozyme transgene reduces in vitro invasion and migration in prostate cancer cells.

BACKGROUND: Hepatocyte growth factor scatter factor (HGF/SF) elicits a number of biological activities including invasion and migration through activation of its tyrosine kinase receptor c-Met. Over expression of c-Met has been implicated in prostate cancer development and progression. This study examined the effect of a ribozyme transgene, designed to inhibit human c-Met expression, and its impact on in vitro invasion and migration in prostate cancer. METHODS: A transgene (Met 560) consisting of U1 snRNA, hammerhead ribozyme, and antisense was cloned into a modified pZeoU1-EcoSpe vector and transfected into DU-145 cells. The effect of HGF/SF was tested on prostate cancer cells whose expression of c-Met had been blocked by way of a ribozyme transgene. RESULTS: Met 560 stable transfectants (DU-145(+/+)) manifested a complete loss of c-Met expression at mRNA and protein levels. In contrast, control plasmid (DU-145(+/-)) and wild-type DU-145 cells (DU-145(-/-)) had similar levels of c-Met expression. HGF/SF significantly increased the in vitro invasiveness (mean 47.71 +/- SE 7.75; P < 0.01 vs. control 24.14 +/- 1.34), and migration (mean 48.44 +/- SE 3.51; P < 0.01 vs. control 22.95 +/- 1.47) of DU-145(-/-) cells, respectively. Similarly, HGF/SF also increased the invasion (62.33 +/- 6.34; P < 0.001 vs. control 24.5 +/- 2.35) and migration (46.14 +/- 2.26; P < 0.01 vs. control 21.82 +/- 1.62) of DU-145(+/-) cells. In contrast, DU-145(+/+) cells had lost its response to HGF/SF induced invasion (22.33 +/- 2.08; P > 0.05 vs. control 23.5 +/- 2.11) and migration (24.12 +/- 0.86; P > 0.05 vs. control 23.27 +/- 0.81). CONCLUSIONS: Targeting the HGF/SF receptor by way of a hammerhead ribozyme encoding antisense to c-Met, is an effective method to reduce the invasive or migration potential in prostate cancer, and may have important therapeutic implications.

Hepatocyte growth factor in kidney fibrosis: therapeutic potential and mechanisms of action.

Hepatocyte growth factor (HGF) is a pleiotropic factor that plays an imperative role in tubular repair and regeneration after acute renal injury. Growing evidence indicates that HGF is also an endogenous renoprotective factor that possesses a potent antifibrotic ability. HGF prevents the initiation and progression of chronic renal fibrosis and inhibits transforming growth factor (TGF)-beta(1) expression in a wide variety of animal models. In vitro, HGF counteracts the action of TGF-beta(1) in different types of kidney cells, resulting in blockade of the myofibroblastic activation from interstitial fibroblasts and glomerular mesangial cells, as well as inhibition of the mesenchymal transition from tubular epithelial cells. Recent studies reveal that HGF antagonizes the profibrotic actions of TGF-beta(1) by intercepting Smad signal transduction through diverse mechanisms. In interstitial fibroblasts, HGF blocks activated Smad-2/3 nuclear translocation, whereas it specifically upregulates the expression of the Smad transcriptional corepressor SnoN in tubular epithelial cells. In glomerular mesangial cells, HGF stabilizes another Smad corepressor, TGIF, by preventing it from degradation. Smad corepressors bind to activated Smad-2/3 and sequester their ability to transcriptionally activate TGF-beta target genes. This article reviews recent advances in our understanding of the cellular and molecular mechanisms underlying HGF inhibition of renal fibrosis.

The tumour-stromal interaction between intratumoral c-Met and stromal hepatocyte growth factor associated with tumour growth and prognosis in non-small-cell lung cancer patients.

Immunohistochemical analyses of the effects of hepatocyte growth factor (HGF) and c-Met expression on tumour growth and angiogenesis were performed on 88 patients with non-small-cell lung cancers (NSCLCs). In all, 22 carcinomas (25.0%) were intratumoral HGF-positive, 14 carcinomas (15.9%) were stromal HGF-positive, and 36 carcinomas (40.9%) were intratumoral c-Met-positive. None of the carcinomas were stromal c-Met-positive. Examination of tumour growth revealed that the frequency of tumours with a high Ki-67 index was significantly greater for stromal HGF-positive tumours than for stromal HGF-negative tumours (P=0.0197). The frequency of tumours with a high Ki-67 index was also significantly greater for intratumoral c-Met-positive tumours than for intratumoral c-Met-negative tumours (P=0.0301). However, there was no significant difference in tumour vascularity with relation to intratumoral HGF status, stromal HGF status, and intratumoral c-Met status. The survival rate of patients with intratumoral c-Met-positive tumours was significantly lower than for patients with c-Met-negative tumours (P=0.0095). Furthermore, the survival rate of patients with both intratumoral c-Met-positive and stromal HGF-positive tumours was significantly lower than for patients with either positive tumours, and that of patients with both negative tumours (P=0.0183 and P=0.0011, respectively). A univariate analysis revealed that intratumoral c-Met expression was a significant prognostic factor of NSCLC patients (relative risk=2.642, P=0.0029). The present study demonstrates that tumour-stromal interaction between tumour cell-derived c-Met and stromal cell-derived HGF affects tumour growth and the prognosis of NSCLC patients.