Animals ; Hepatocyte Growth Factor ; metabolism ; Humans ; Proto-Oncogene Proteins c-met ; Serine Endopeptidases

This research aims to construct a lentiviral expression vector carrying the extracelluar domain (ED) of human hepatocyte growth factor receptor (C-Met), and to express it in transfected 293T cells. The extracellular domain of C-Met was amplified by RT-PCR, ligated with lentiviral expression vector p RRL-CMV-ED, and then expressed in 293T cell line. The expressed protein was purified and identified by RT-PCR and Western blot. The enzyme digestion and sequence analysis showed that the lentiviral expression vector p RRL-CMV-ED was constructed correctly. The size of amplified genes was about 2 700 bp. The purified protein with Ni-affinity column was about 105 kD analyzed by SDS-PAGE. The Western blot and ELISA results showed that the expressed protein which could bind to HGF specifically was the extracelluar domain of human hepatocyte growth factor receptor. This research may lay a foundation for further study of anti-C-MET monoclonal antibody and neutralizing antibody.
Genetic Vectors ; HEK293 Cells ; Humans ; Lentivirus ; Proto-Oncogene Proteins c-met ; genetics ; metabolism ; Transfection

Humans ; Proto-Oncogene Proteins c-met ; genetics ; metabolism ; Stomach Neoplasms ; genetics ; metabolism

BACKGROUND: Meningiomas show high recurrence rates even after curative tumor removal. The invasiveness of meningiomas may contribute to their high recurrence rates. Recently, c-MET and hepatocyte growth factor (HGF) have been reported to be involved in cancer invasion. METHODS: We examined the immunohistochemical expression of c-MET and HGF in 100 cases of patients with meningiomas who have undergone complete tumor removal. RESULTS: c-MET(-High) and HGF(-High) were found in 17% and 13% of meningiomas, respectively. Brain invasion was observed in 17.6% of c-MET(-High) meningiomas, but in only 2.4% of c-MET(-Low) meningiomas (p=.033). Bone/soft tissue invasion was observed in 23.5% of c-MET(-High) meningiomas and in 9.6% of c-MET(-Low) meningiomas (p=.119). HGF(-High) did not show statistical association with brain invasion or bone/soft tissue invasion. c-MET(-High) demonstrated shorter recurrence-free survival (RFS, 93.5+/-8.2 months vs 96.1+/-1.9 months); however, this difference was not statistically significant (p=.139). There was no association of HGF(-High) with RFS. CONCLUSIONS: This study demonstrates that c-MET(-High) is associated with brain invasion of meningiomas, and that c-MET expression may be a useful predictive marker for meningioma recurrence. Patients with invasive meningiomas with high expressions of c-MET may be good candidates for targeted therapy using c-MET inhibitors.
Brain ; Hepatocyte Growth Factor ; Humans ; Immunohistochemistry ; Meningioma* ; Neoplasm Invasiveness ; Proto-Oncogene Proteins c-met ; Recurrence

BACKGROUNDMyopia is a common disorder and the incidence has increased yearly, but its pathogenesis remains unclear. The aim of this study was to investigate the possible role of hepatocyte growth factor (HGF) and its receptor c-Met in the development of lens-induced myopia in guinea pigs.

METHODSSixty one-week-old guinea pigs were chosen. The right eyes were treated with -10.0 diopters (D) lenses as the lens-induced myopia group; the left eyes remained untreated as the control group. Six weeks later, refractive status and axial length were determined by streak retinoscopy and A-scan ultrasonography, respectively. The guinea pigs were killed and both eyes collected. Morphological changes were observed by hematoxylin and eosin staining. The expression levels of HGF, c-Met, and matrix metalloproteinase 2 (MMP-2) mRNA and protein in the posterior sclera were analyzed by RT-PCR and Western blotting, respectively.

RESULTSThe lens-induced myopia group became myopic with a significant increase in axial length and a significant decrease in refraction. Compared with the control group, the posterior retina and sclera were thinner in the lens-induced myopia group. The expression levels of HGF and MMP-2 mRNA and protein and of phosphorylated c-Met protein were significantly higher in the posterior sclera of the lens-induced myopia group than in the control group (all P < 0.05). In the lens-induced myopia group, the expression level of MMP-2 in the posterior sclera positively correlated with the expression level of HGF (r = 0.902, P < 0.05) and phosphorylated c-Met (r = 0.885, P < 0.05).

CONCLUSIONHGF/c-Met might play a role in the development of lens-induced myopia in guinea pigs by upregulating the expression of MMP-2.

Animals ; Guinea Pigs ; Hepatocyte Growth Factor ; metabolism ; Myopia ; etiology ; metabolism ; Proto-Oncogene Proteins c-met ; metabolism

OBJECTIVE: The pathologic diagnosis of the astrocytoma has been primarily based on the histologic grading, however, there are some discrepancies among the pathologists on the tumor grading. Met protein, known as the hepatocyte growth factor receptor, is a transmembrane 190 kDa heterodimer with tyrosine kinase activity, encoded by c-met gene. Although c-Met protein is known to be expressed in a variety of tissues and plays important roles in signal transduction, the study on its expression related to clinicopathological prognostic parameters in brain tumor is rare. METHODS: We have evaluated c-Met protein expression in association with p53 and Ki-67 expression in 35 astrocytic tumors (15 diffuse astrocytomas: LGA, 11 anaplastic astrocytomas: AA, 9 Glioblastoma multiforme: GBM) using immunohistochemical method. RESULTS: c-Met immunoreactivity was observed in 2 LGA(13.3%), 5AA(45.5%), 4GBM cases (44.4%), respectively. p53 immunoreactivity was observed in 2 LGA(13.3%), 4AA(36.4%), 4GBM cases (44.4%), respectively. Ki-67 labelling index was 1.7+/-1.0% (LGA), 13.3+/-.2% (AA) and 18.0+/-.1% (GBM), respectively. Each c-Met expression and the Ki-67 labelling index were statistically correlated between low grade and anaplastic astrocytomas. The c-Met and p53 expression rate were not associated with increased Ki-67 labelling index. But, c-Met, p53, Ki-67 expression tended to increase with higher grade of malignancy. CONCLUSION: We conclude that c-Met expression may contribute to the invasiveness and tumor progression of the astrocytoma and c-Met expression is useful in discrimination between low grade astrocytoma and anaplastic astrocytoma.
Astrocytoma ; Brain Neoplasms ; Diagnosis ; Discrimination (Psychology) ; Glioblastoma ; Neoplasm Grading ; Protein-Tyrosine Kinases ; Proto-Oncogene Proteins c-met ; Signal Transduction

PURPOSE: E-cadherin is an adhesion molecule essential for tight connection between cells, forming the cadherin/catenin complex. Truncated beta-catenin disrupts the interaction between E-cadherin and alpha-catenin, leading to the loss of intercellular adhesion. Met protein, the hepatocyte growth factor receptor, plays important roles in signal transduction. We investigated the relationships between the expressions of E-cadherin, beta-catenin, and c-met protein and the clinicopathological and prognostic parameters in gastric adenocarcinomas. MATENRIALS AND METHODS: The patterns of E-cadherin, beta- catenin, and c-met protein expression were studied using immunohistochemistry in formalin-fixed, paraffin-embedded archival tissues from 76 surgically resected gastric adenocarcinomas. RESULTS: Increased expressions of E-cadherin, beta-catenin, and c-met were more significantly correlated in early gastric cancers (EGC) than in advanced gastric cancers (AGC) (P=0.002, P=0.003 and P=0.026). The positive immunoreactivities of all three markers were markedly lower in signet ring-cell type and poorly differentiated type lesions than in intestinal-type lesions. Decreased expression of the beta-catenin protein correlated well with increased tumor invasion depth (P=0.039), and increased lymph node metastasis correlated well with reduced expression of c-met (P=0.046). CONCLUSION: In gastric cancers, reduced expressions of the E-cadherin, beta-catenin, and c-met proteins may play some role in poorer tumor differentiation, deeper tumor invasion, and increased lymph node metastasis. Also, the c-met gene is thought to play a specific role in the mechanism of the yet unknown catenin action.
Adenocarcinoma* ; alpha Catenin ; beta Catenin* ; Cadherins* ; Immunohistochemistry ; Lymph Nodes ; Neoplasm Metastasis ; Proto-Oncogene Proteins c-met ; Signal Transduction ; Stomach Neoplasms

Recepteur d'origine nantais (RON) is a receptor tyrosine kinase belonging to the subfamily of which c-MET is the prototype. Large epidemiologic studies have confirmed the strong association between RON and gastric cancer development. Constitutive activation of RON signaling directly correlates with tumorigenic phenotypes of gastric cancer and a poor survival rate in advanced gastric cancer patients. In this review, we focus on recent evidence of the aberrant expression and activation of RON in gastric cancer tumors and provide insights into the mechanism of RON signaling associated with gastric cancer progression and metastasis. Current therapeutics against RON in gastric cancer are summarized.
Epidemiologic Studies ; Humans ; Neoplasm Metastasis ; Phenotype ; Protein-Tyrosine Kinases ; Proto-Oncogene Proteins c-met ; Stomach Neoplasms ; Survival Rate

OBJECTIVETo study the effects of lipid rafts on cell signal transmembrane transduction mediated by c-Met.

METHODSAfter HepG2Cells were treated with MbCD to disrupt the lipid rafts and were treated with artificial recombination hepatocyte growth factor to activate c-Met, the activities of PLCr1/PKC, PI3K/Akt and MAPK signaling pathways in HepG2 cells were analyzed using Western blot.

RESULTS(1) After disruption of lipid rafts with MbCD, phosphorylation of PLCr1 decreased by 35% (P = 0.022); the content of PLCr in the cytoplasm increased by 1.75 fold (P = 0.017); PLCr1 conjugated with membrane decreased by 30% (P = 0.037). (2) The content of PKB in the cytosol decreased by 38% (P = 0.028), and the phosphorylation level of PKB conjugated with membrane decreased by 14% (P = 0.041). At the same time, PDK translocation from cytosol to the plasma membrane and its activation were inhibited by treatment with MbCD. (3) Treatment with MbCD had no significant effect on ErK/MAPK, p38/MAPK and JNK/MAPK signaling pathways.

CONCLUSIONDisruption of lipid rafts with MbCD inhibits the activation of PLCr1/PKC and PI3K/PKB signaling pathways by HGF/cMet, but has no effect on MAPK signaling pathway.

Hep G2 Cells ; Humans ; Membrane Microdomains ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Phospholipase C gamma ; metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; metabolism ; Proto-Oncogene Proteins c-met ; metabolism ; Signal Transduction

PURPOSE: The hepatocyte growth factor, (HGF)/c-Met, pathway may play various roles in the carcinogenesis of various organs. HGF, a ligand for c-Met, is a pleiotrophic factor that was originally identified as a polypeptide growth factor for hepatocytes. Met protein, known as the HGF receptor, is a transmembrane 190 kDa heterodimer with tyrosine kinase activity, which is encoded by the c-met oncogene. The HGF/ c-Met signalling pathway has been shown to demonstrate various cellular responses including mitogenic, proliferative, morphogenic and angiogenic activities. Although the c-met gene is known to be expressed in a variety of tissues and play important roles in signal transduction, studies of its expression in thyroid tumors are rare. Our objectives were to evaluate the c-met gene expression in benign and malignant thyroid tumors and to correlate this with various clinicopathological facors. METHODS: In this study, the mRNA expression of the c-met was examined by means of a RT-PCR method and the from immunohistochemical expression of c-Met protein in 100 cases of thyroid tumors cases, including 50 papillary carcinomas (pc), 10 follicular carcinomas (fc), and 20 follicular adenomas (fa), 20 nodular hyperplasia (nh). RESULTS: c-met mRNA expression was detected in 10, 20, 40 and 86% of the nh, fa, fc and pc, respectively. Also, c-Met protein expression was detected in 5, 15, 20 and 88% of the nh, fa, fc and pc, respectively. Especially, the c-Met protein expression was higher in well differentiated papillary carcinomas than those that were poorly differentiated, and was statistically significant. Correlation between c-met mRNA and protein expression was recognized in papillary carcinomas. CONCLUSION: These results suggest that the expression of c-met gene expression may be associated with the development of papillary carcinomas of the thyroid. Also, both c-met mRNA and protein expressions may contribute to the morphogenesis of well differentiated papillary carcinomas.
Adenoma ; Carcinogenesis ; Carcinoma, Papillary ; Gene Expression ; Hepatocyte Growth Factor ; Hepatocytes ; Hyperplasia ; Morphogenesis ; Oncogenes ; Protein-Tyrosine Kinases ; Proto-Oncogene Proteins c-met ; RNA, Messenger ; Signal Transduction ; Thyroid Gland*