Targeted therapy is an important therapeutic method for advanced non-small cell lung cancer with driver gene alteration.However,resistance to targeted therapy will inevitably happen in clinical practice,which has become a major issue demanding prompt solution.Studies have demonstrated that bypass resistance mediated by the activation of hepatocyte growth factor(HGF)/mesenchymal-epithelial transition factor(MET)signaling pathway is a common cause of resistance to targeted therapy.Presently,relevant studies have accumulated rich experience in the specific mechanisms.To be brief,HGF/MET is an important target for overcoming the resistance to targeted therapy and promises to be a leading biomarker for judging and observing the occurrence of resistance.This paper introduces the recent studies concerning the effects and mechanisms of HGF/MET signaling pathway on resistance to targeted therapy.
Carcinoma, Non-Small-Cell Lung/genetics* ; Epithelial-Mesenchymal Transition ; Hepatocyte Growth Factor ; Humans ; Lung Neoplasms/genetics* ; Proto-Oncogene Proteins c-met/metabolism* ; Signal Transduction

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

OBJECTIVETo explore the correlation of c-met protein with the clinical staging and cell differentiation of esophageal squamous cell carcinoma (ESCC).

METHODSA total of 100 patients with ESCC were enrolled were examined for expression of c-met protein using immunohistochemistry, and the patients in negative and positive c-met expression groups were compared for clinicopathological characteristics and overall survival.

RESULTSs The 100 ESCC patients included 67 male and 33 female patients with a median age of 59 years; 49 of the patients were negative and 51 were positive for c-met expression. Positive c-met expression was significantly correlated with advanced TMN stages and lower tumor differentiation. Kaplan-Meier survival curve showed that the median survival time of c-met-positive patients was significantly reduced compared with that of c-met-negative patients (30.9 vs 48.2 months, P<0.05). COX regression analysis showed that c-met was a independent risk factor for the overall survival of the patients (HR: 2.34, 95% CI: 1.63-4.54, P<0.05).

CONCLUSIONA positive expression of c-met protein is significantly correlated with an advanced TMN stage, lower tumor differentiation and a poor prognosis, and may serve as a indicator for predicting the prognosis of ESCC.

Carcinoma, Squamous Cell ; diagnosis ; metabolism ; Esophageal Neoplasms ; diagnosis ; metabolism ; Female ; Humans ; Immunohistochemistry ; Kaplan-Meier Estimate ; Male ; Middle Aged ; Neoplasm Staging ; Prognosis ; Proportional Hazards Models ; Proto-Oncogene Proteins c-met ; metabolism ; Risk Factors

Objective To investigate the expressions of CD44,CD47,and c-met in ovarian clear cell carcinoma (OCCC) tissue and their correlations with clinical variables and prognosis. Methods Immunohistochemical method was used to investigate the expressions of CD44,CD47,and c-met in tissues from 86 OCCC patients and the relationships of their expressions with the clinicopathological factors of OCCC were analyzed. Results The expressions of CD44,CD47,and c-met were significantly high in OCCC tissues (90.7%,91.9%,and 94.2%,respectively). The strong positive expressions of CD44 and CD47 were significantly correlated with advanced International Federation of Gynecology and Obstetrics stages,chemotherapeutic resistance,and poor prognosis (all P<0.05),the strong positive expression of c-met was significantly correlated with chemotherapeutic resistance and poor prognosis (all P<0.05),whereas there was no correlation between the strong positive expressions of CD44,CD47,and c-met and the lymphatic node metastasis. COX survival analysis revealed that advanced International Federation of Gynecology and Obstetrics stages and high expressions of CD44,CD47 and c-met were independent risk factors for poor prognosis (P<0.05). There was a positive correlation between CD44 (or CD47) and c-met and between CD44 and CD47 (the Spearman correlation coefficient rwas 0.783,0.776,and 0.835,respectively,all P<0.01). Conclusions The expressions of CD44,CD47,and c-met increase in OCCC tissues and are correlated with each other. High expressions of CD44,CD47,and c-met are independent factors for poor prognosis.
Adenocarcinoma, Clear Cell ; metabolism ; CD47 Antigen ; metabolism ; Female ; Humans ; Hyaluronan Receptors ; metabolism ; Lymphatic Metastasis ; Ovarian Neoplasms ; metabolism ; Prognosis ; Proto-Oncogene Proteins c-met ; metabolism ; Survival Analysis

The hepatocyte growth factor ( HGF) is a multifunctional growth factor, which produces multiple biological effects by binding to the c-Met acceptor. This article reviews the biological properties of HGF, particularly those correlated with male reproduction, including its abilities to promote testis embryonic development, spermatogenesis, and testosterone synthesis of Leydig cells. HGF may provide a new insight into the treatment of male hypogonadism and infertility.
Embryonic Development ; Hepatocyte Growth Factor ; physiology ; Humans ; Leydig Cells ; metabolism ; Male ; Proto-Oncogene Proteins c-met ; metabolism ; Reproduction ; physiology ; Spermatogenesis ; physiology ; Testis ; embryology ; Testosterone ; biosynthesis

OBJECTIVETo investigate the ability of invasion and migration of breast cancer MDA-MB-231 cells under serum starvation and hypoxia, and the effect of antiangiogenic drugs, rh-endostatin and bevacizumab, on the ability of invasion and migration of breast cancer cells under serum starvation and/or hypoxia, in order to explore the potential risk of antiangiogenic therapy in clinics.

METHODSThe cells were randomized into 4 groups, i.e., group A: 10% fetal bovine serum (FBS) group; group B: hypoxia + 10% FBS group; group C: serum starvation group; group D: hypoxia + serum starvation group; each group was further divided into three subgroups as blank control, treated with rh-endostatin and bevacizumab, respectively. Cell counting kit-8 (CCK-8) was used to assess the inhibition rate of cell growth induced by endostatin and bevacizumab, in order to determine the proper working concentration and time of the two drugs. Transwell assay was conducted to detect the cell invasion and migration in vitro. The expressions of c-Met and MMP-9 were detected by Western blot. The cells treated with rh-endostatin or bevacizumab under serum starvation were tested by hybridization using Exiqon miBase 18.0 microarray. The miRNAs which exibited significant differences (P < 0.05) in miRNA hybridization were verified by real-time PCR assay.

RESULTSCCK-8 assay showed that the inhibition rates of MDA-MB-231 cells cultured with 800 mg/L rh-endostatin for 48 h and 24 h were (32.2 ± 2.5)% and (27.0 ± 1.3)%, respectively, showing a significant difference (P = 0.023). The inhibition rates of MDA-MB-231 cells cultured with 80 mg/L bevacizumab for 48 h and 24 h were (30.5 ± 1.4) % and (26.1 ± 2.4) %, respectively, showing also a significant difference (P = 0.015). The Transwell assay showed that in the starvation blank group, the number of invaded and penetrated cells were 28.8 ± 2.2 and 31.4 ± 1.5, respectively, significantly different from that in the rh-endostatin and bevacizumab groups (P < 0.05). The relative expressions of c-Met and MMP-9 were 0.213 ± 0.017 and 0.542 ± 0.048, respectively, with a significant difference from those of the groups treated with each drug (P < 0.05 for both). The numbers of penetrated cells in the Transwell assay treated with rh-endostatin in hypoxia were 17.5 ± 2.1 and 16.5 ± 2.8, respectively, and the numbers of penetrated cells in the Transwell assay treated with bevacizumab were 16.3 ± 3.5 and 17.5 ± 2.4, respectively, showing no significant difference among them (P > 0.05 for both). The ability of migration and invasion of MDA-MB-231 cells and the expression of c-Met and MMP-9 were not impacted by hypoxia (P > 0.05). Real-time PCR assay showed that only the levels of miR-2355 and miR375 were significantly and stably decreased in the cells which had increased ability of invasion and migration. The relative expression levels of miR375 and miR-2355 in the serum starvation blank group were 0.550 ± 0.036 and 0.852 ± 0.121, respectively, significantly lower than that in the groups treated with rh-endostatin or bevacizumab (P<0.05). In the serum starvation group, the expression levels of miR375 and miR-2355 of cells treated with rh-endostatin were 0.295 ± 0.012 and 0.253 ± 0.011, and the expression levels of cells treated with bevacizumab were 0.234 ± 0.020 and 0.309 ± 0.022, respectively, (P > 0.05 for all). Compared with the serum starvation blank group, the expression levels of miR2355 and miR375 were significantly decreased when cells were treated with rh-endostatin/bevacizumab under serum starvation, but no significant difference was found between the two drugs (P > 0.05). However, hypoxia did not affect the expressions of miR2355 and miR375 (P > 0.05).

CONCLUSIONSThe results of this study suggest that serum starvation can increase the ability of invasion and migration of breast cancer cells. Furthermore, both rh-endostatin and bevacizumab may enhance their invasion and penetration ability under serum starvation condition.

Angiogenesis Inhibitors ; adverse effects ; Bevacizumab ; adverse effects ; Breast Neoplasms ; pathology ; Cell Hypoxia ; Cell Line, Tumor ; Cell Movement ; drug effects ; Cell Proliferation ; drug effects ; Culture Media, Serum-Free ; Endostatins ; adverse effects ; Female ; Humans ; Matrix Metalloproteinase 9 ; metabolism ; MicroRNAs ; analysis ; Neoplasm Invasiveness ; Proto-Oncogene Proteins c-met ; metabolism ; Random Allocation ; Real-Time Polymerase Chain Reaction ; Time Factors

OBJECTIVETo study the effect and mechanism of bevacizumab on proliferation and invasion of human lung cancer A549 cells.

METHODSA549 cells were treated with bevacizumab. Proliferation and invasion of the bevacizumab-treated A549 cells were detected using cell counting kit CCK-8 and Transwell assay, respectively. The expression of the mRNA and protein of MMP-2, MMP-9 and c-Met were detected by real-time PCR and Western blotting, respectively.

RESULTSProliferation activity was inhibited at the concentration of 10 µg/ml and promoted at the concentration of 100 µg/ml bevacizumab. Bevacizumab in the concentration of 50 µg/ml had a stronger inhibitory effect on the invasion of A549 cells (16 406.19 ± 5 674.23 penetrated cells) than that of control group (36 108.68 6 263.83, P<0.05). The real-time PCR showed that bevacizumab had a stronger inhibitory effect on the expression of MMP-2 and MMP-9 mRNA at the concentration of 50 µg/ml and on the expression c-Met mRNA at the concentration of 10 µg/ml bevacizumabin the A549 cells. However bevacizumab at the concentration of 100 µg/ml showed a promoting effect on the expression of MMP-2, MMP-9 and c-Met mRNA (1.82 ± 0.31, 1.60 ± 0.25, 2.63 ± 0.48), significantly higher than that of the control group (1.00 ± 0.19, 1.00 ± 0.23, 1.00 ± 0.22, P<0.05). The expression of MMP-2, MMP-9 and c-Met mRNA and protein was inhibited by 10 µg/ml bevacizumab in a time-dependent manner. The Western blot assay showed that bevacizumab had a bi-directional effect on the expression of MMP-2 and c-Met proteins in the A549 cells: a promoting effect at 100 µg/ml and inhibitory effect on the expression of MMP-2 at 50 µg/ml bevacizumab, and inhibitory effect on the expression of c-Met protein at 10 µg/ml bevacizumab.

CONCLUSIONSOur findings indicate that in a certain range of concentrations, bevacizumab has prominent inhibitory effect on the proliferation and invasion of A549 cells. However,over the concentration of 100 µg/ml, bevacizumab shows a weakening anti-invasion effect, even has a promoting effect on cell proliferation. This phenomenon may be related to the inhibiting effect on the expression of MMP-2 and c-Met proteins in a non-concentration-dependent manner by bevacizumab.

Angiogenesis Inhibitors ; pharmacology ; Bevacizumab ; pharmacology ; Blotting, Western ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; drug effects ; Enzyme Inhibitors ; pharmacology ; Humans ; Lung Neoplasms ; metabolism ; pathology ; Matrix Metalloproteinase 2 ; metabolism ; Matrix Metalloproteinase 9 ; metabolism ; Neoplasm Invasiveness ; Proto-Oncogene Proteins c-met ; metabolism ; RNA, Messenger ; metabolism ; Real-Time Polymerase Chain Reaction

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

OBJECTIVETo observe the inhibition of NK4 protein in the proliferation of human Raji lymphoma xenografts in nude mice, and to explore its molecular mechanism.

METHODSModels of human Raji lymphoma xenograft transfected with HGF gene were established by subcutaneous inoculation in nude mice. After establishment of the models, the mice received continuous NK4 protein via tail vein for 4 weeks, and the weight and tumor growth were monitored every week. After 8 weeks, the expression of HGF mRNA and c-Met mRNA of tumor tissues was measured by real-time fluorescent quantitation PCR. The apoptotic index (AI) and microvessel density (MVD) were evaluated by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) and immunohistochemistry, respectively.

RESULTSThe models of human Raji lymphoma xenograft were successfully established. Although the animal weights of all groups declined, especially in the groups with NK4 protein injection, there was no statistical significance (P > 0.05). The tumor volume in HGF gene transfected group was larger than those of the control groups (P < 0.01), and there was no statistical significance among the control groups (P > 0.05). However, the tumor volume of the NK4 protein injection group decreased significantly (P < 0.01). Expression of HGF mRNA and c-Met mRNA in HGF gene transfected group increased significantly after injection of NK4 protein (P < 0.01). AI in HGF gene transfected group (33.5% ± 12.3%) was significantly lower than that of control groups (89.1% ± 22.3% vs. 81.9% ± 27.0%, P < 0.05), but became significantly higher (119.1% ± 18.9%) after NK4 protein injection (P < 0.01). MVD in HGF gene transfected group (28.5 ± 2.0) was higher than that of control groups (12.2 ± 1.4, 13.8 ± 1.3, P < 0.01), although declined (15.5 ± 2.5) after NK4 protein injection (P < 0.01).

CONCLUSIONSNK4 protein suppresses significantly the growth of human Raji lymphoma xenografts transfected with HGF gene. The pathogenesis may be involved in promoting tumor cell apoptosis and restraining tumor angiogenesis through competitive interrupting HGF/Met signal pathway.

Animals ; Apoptosis ; Hepatocyte Growth Factor ; genetics ; metabolism ; Heterografts ; Humans ; Lymphoma ; genetics ; metabolism ; therapy ; Mice ; Mice, Nude ; Microvessels ; pathology ; Neovascularization, Pathologic ; Proto-Oncogene Proteins c-met ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Signal Transduction ; T-Box Domain Proteins ; administration & dosage ; Transfection ; Transplantation, Heterologous

The C-terminal fragment of the c-Met receptor tyrosine kinase is present in the nuclei of some cells irrespective of ligand stimulation, but the responsible nuclear localization signal (NLS) has not been previously reported. Here, we report that two histidine residues separated by a 10-amino-acid spacer (H1068-H1079) located in the juxtamembrane region of c-Met function as a putative novel NLS. Deletion of these sequences significantly abolished the nuclear translocation of c-Met, as did substitution of the histidines with alanines. This substitution also decreased the association of c-Met fragment with importin beta. The putative NLS of c-Met is unique in that it relies on histidines, whose positive charge changes depending on pH, rather than the lysines or arginines, commonly found in classical bipartite NLSs, suggesting the possible 'pH-dependency' of this NLS. Indeed, decreasing the cytosolic pH either with nigericin, an Na+/H+ exchanger or pH 6.5 KRB buffer significantly increased the level of nuclear c-Met and the interaction of the c-Met fragment with importin beta, indicating that low pH itself enhanced nuclear translocation. Consistent with this, nigericin treatment also increased the nuclear level of endogenous c-Met in HeLa cells. The putative aberrant bipartite NLS of c-Met seems to be the first example of what we call a 'pH-dependent' NLS.
Active Transport, Cell Nucleus ; Amino Acid Sequence ; HeLa Cells ; Humans ; Hydrogen-Ion Concentration ; Molecular Sequence Data ; *Nuclear Localization Signals ; Protein Structure, Tertiary ; Proto-Oncogene Proteins c-met/*analysis/genetics/*metabolism ; Sequence Deletion