Characterization of MET Alterations in 37 Gastroesophageal Cancer Cell Lines for MET-Targeted Therapy.

Capmatinib and savolitinib, selective MET inhibitors, are widely used to treat various MET-positive cancers. In this study, we aimed to determine the effects of these inhibitors on MET-amplified gastric cancer (GC) cells. Methods: After screening 37 GC cell lines, the following cell lines were found to be MET-positive with copy number variation >10: SNU-620, ESO51, MKN-45, SNU-5, and OE33 cell lines. Next, we assessed the cytotoxic response of these cell lines to capmatinib or savolitinib alone using cell counting kit-8 and clonogenic cell survival assays. Western blotting was performed to assess the effects of capmatinib and savolitinib on the MET signaling pathway. Xenograft studies were performed to evaluate the in vivo therapeutic efficacy of savolitinib in MKN-45 cells. Savolitinib and capmatinib exerted anti-proliferative effects on MET-amplified GC cell lines in a dose-dependent manner. Savolitinib inhibited the phosphorylation of MET and downstream signaling pathways, such as the protein kinase B (AKT) and extracellular signal-regulated kinase (ERK) pathways, in MET-amplified GC cells. Additionally, savolitinib significantly decreased the number of colonies formed on the soft agar and exerted dose-dependent anti-tumor effects in an MKN-45 GC cell xenograft model. Furthermore, a combination of trastuzumab and capmatinib exhibited enhanced inhibition of AKT and ERK activation in human epidermal growth factor receptor-2 (HER2)- and MET-positive OE33 cells. Targeting MET with savolitinib and capmatinib efficiently suppressed the growth of MET-amplified GC cells. Moreover, these MET inhibitors exerted synergistic effects with trastuzumab on HER2- and MET-amplified GC cells.

Endogenous Pancreatic Cancer Cell PD-1 Activates MET and Induces Epithelial-Mesenchymal Transition to Promote Cancer Progression.

We recently demonstrated that immune checkpoint PD-1 was endogenously expressed in pancreatic ductal adenocarcinoma (PDAC) cells. Our data indicated that PD-1 proteins are not exclusive to immune cells and have unrecognized signal transduction cascades intrinsic to cancer cells. Building on this paradigm shift, we sought to further characterize PD-1 expression in PDAC. We utilized a phospho-explorer array to identify pathways upregulated by PD-1 signaling. We discovered PD-1-mediated activation of the proto-oncogene MET in PDAC cells, which was dependent on hepatocyte growth factor (MET ligand) and not secondary to direct protein interaction. We then discovered that the PD-1/MET axis in PDAC cells regulated growth, migration, and invasion. Importantly, the PD-1/MET axis induced epithelial-to-mesenchymal transition (EMT), a well-established early oncogenic process in PDAC. We observed that combined targeting of PDAC cell PD-1 and MET resulted in substantial direct tumor cell cytotoxicity and growth inhibition in PDAC cell lines, patient-derived organoids, and patient-derived xenografts independent of cytotoxic immune responses. This is the first report of PDAC-endogenous PD-1 expression regulating MET signaling, which builds upon our growing body of work showing the oncogenic phenotype of PD-1 expression in PDAC cells is distinct from its immunogenic role. These results highlight a paradigm shift that the tumor-specific PD-1 axis is a novel target to effectively kill PDAC cells by antagonizing previously unrecognized PD-1-dependent oncogenic pathways.

Targeting MET in cancer therapy.

MET encodes a receptor tyrosine kinase c-MET for hepatocyte growth factor (HGF). The specific combination of c-MET and HGF activates downstream signaling pathways to trigger cell migration, proliferation, and angiogenesis. MET exon 14 alterations and MET gene amplification play a critical role in the origin of cancer. Several monoclonal antibodies and small-molecule inhibitors of c-MET have been evaluated in clinical trials. In patients with advanced non-small cell lung cancer, cabozantinib and crizotinib showed clear efficacy with a generally tolerable adverse events profile. In gastrointestinal cancers, most phase III trials of MET inhibitors showed negative results. In hepatocellular carcinoma, based on the encouraging results of some phase II studies, a series of phase III trials are currently recruiting patients to access the efficacy and safety of MET inhibitors.

Relationship between abnormal activation of HGF/c-Met signaling pathway and EGFR-TKI acquired resistance in non-small cell lung cancer / 国际肿瘤学杂志

Targeted therapy such as the epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI)has made huge progress in treatment of non-small cell lung cancer (NSCLC).However,the emergence of acquired drug resistance is an inevitable result of the targeted therapy.The hepatocyte growth fac-tor/c-mesenchymal-epithelial transition factor (HGF /c-Met)signaling pathway participates in cell formation, migration,angiogenesis and other important cellular processes of multiple tumors.The abnormal activation of this signaling pathway plays the pivotal role in the acquired resistance to EGFR-TKI.Recently,some clinic tri-als prove that HGF /c-Met inhibitors can make clinical benefit of some NSCLC patients with acquired drug re-sistance of EGFR-TKI.

The mechanism by which bone marrow mesenchymal stem cells participate in apoptosis of hepatic stellate cells / 中国组织工程研究

BACKGROUND:Control of hepatic stelate cel activation and proliferation is the focus of developing strategies against liver fibrosis. Human or murine bone marrow mesenchymal stem cels can induce apoptosis of hepatic stelate cels through paracrine of hepatocyte growth factors. OBJECTIVE:To explore the mechanism by which bone marrow mesenchymal stem cels participate in apoptosis of rat hepatic stelate cels. METHODS:Hepatic stelate cels and bone marrow mesenchymal stem cels were seeded and co-cultured in the upper and lower chambers in a co-culture system, serving as a co-culture group. In the blank control group, only hepatic stelate cels were involved. In the c-Met inhibitor group, hepatic stelate cels and bone marrow mesenchymal stem cels were treated with 3 mg/L C-Met inhibitor. In the RhoA inhibitor group, both kinds of cels were treated with 3 mg/L RhoA inhibitor. RESULTS AND CONCLUSION:The concentration of c-Met inhibitor was 3.0 mg/L. RhoA inhibitor at 30μmol/L exhibited a greater inhibitory effect than at other concentrations. RhoA mRNA and protein expression in the co-culture, c-Met inhibitor and in particular RhoA inhibitor groups was obviously greater than in the blank control group. Hepatocyte growth factor concentration in each group was gradualy decreased with time, hepatocyte growth factor activator concentration in each group was gradualy increased with time, and the changes were most obvious in the c-Met inhibitor group. Apoptosis rate of hepatic stelate cels in each group was gradualy increased with time, and highest apoptosis rate appeared in the RhoA inhibitor group, and lowest apoptosis rate in the c-Met inhibitor group. These findings suggest that bone marrow mesenchymal stem cels participate in and promote the apoptosis of hepatic stelate cels by activating hepatocyte growth factors and downregulating Rho activity.

Expressions of APC,bcl-2 and c-met in gastric cancer and its precancerous lesion and their significances / 吉林大学学报(医学版)

Objective To investigate the role of the expressions of APC,bcl-2 and c-met gene in the progress of gastric cancer and their significances in the diagnosis of early gastric cancer.Methods The immunohistochemical technique was used to detect the expressions of APC,bcl-2 and c-met gene in 30 cases of human gastric carcinoma(GC),30 cases of intestinal metaplasia(IM),30 dysplasia(Dys) gastric mucosa,10 gastric adenoma(GA) and 20 normal gastric mucosa.Results ①The positive expression rates of APC in GC,IM,Dys and GA(53.3%,67.7% and 53.3%,respectively) were significantly lower than those in normal gastric mucosa(90.0%,P

Package and titer assay of recombination adeno-associated virus with c-Met short hairpin / 吉林大学学报(医学版)

Objective To package the recombination adeno-associated virus with human U6 promoter and c-met short hairpin in order to establish foundation for research on inhibiting the expression of c-Met and cancer gene therapy.Methods c-Met short hairpin was synthesized and linked to the down stream of U6 promoter by PCR.Adeno-associated viral vectors pSNAVUshMet(1,2) were constructed and transfected into BHK cells.Positive cell clones were selected by G418.Adeno-associated virus with U6shMet were packaged by adding rHSV1-repcap.The virus purity was analysed by SDS-PAGE and titer was assayed by dot blot.Results Two fragments(U6shMet1 and U6shMet2) with c-Met short hairpin were obtained and two recombination adeno-associated virus(rAAVUshMet1 and rAAVUshMet2) with U6shMet were packaged successfully.SDS-PAGE analysis showed that the purified virus appeared clear characterized bands.The virus titer was 4?1012mg?L-1.Conclusion The recombination adeno-associated virus(rAAVUshMet1 and rAAVUshMet2) with U6shMet are constructed successfully.The virus have high titer and good purity and could act as the effective vehicle of inhibiting the expression of c-Met and cancer gene therapy.

Co-expression of cox-2, C-met and beta-catenin in cells forming invasive front of gallbladder cancer.

PURPOSE: Gallbladder cancer is a malignancy with poor prognosis, predominantly resulting from invasion and metastasis. Our previous studies have demonstrated that prostaglandin E(2) (PGE(2)), generated by cyclooxygenase 2 (Cox-2), transactivates epidermal growth factor receptor (EGFR), c-Met and beta-catenin; thus, enhancing colon cancer cell growth and invasiveness in vitro. To determine whether these findings are applicable to clinical conditions, we examined the expression and cellular localization/co-localization of Cox-2, c-Met, beta-catenin, EGFR and c-erbB2 in gallbladder cancer. MATERIALS AND METHODS: Thirty-five specimens of invasive gallbladder cancer, 8 in situ carcinoma and 7 adenoma specimens were immunostained with specific antibodies against Cox-2, c-Met, beta-catenin, EGFR and c-erbB2. The cellular distribution, localization and colocalization were examined, and the signal intensities quantified in: a) the central area of gallbladder cancer and b) cancer cells forming the invasive front. RESULTS: Cox-2, c-Met, beta-catenin, c-erbB2 and EGFR were over-expressed in 80, 74, 71, 62 and 11% of invasive gallbladder cancers, respectively. beta-catenin was expressed in 80% of non-malignant specimens, exclusively in the cell membrane, while the cancer specimens showed cytoplasmic and/or nuclear staining. Significantly higher Cox-2, c-Met and beta-catenin expressions were present in cancer cells of the invasive front than in the tumor central areas (p<0.001), and these expressions were significantly (p=0.01) associated with the invasion depth. Co-expressions of Cox-2, c-Met, beta-catenin and c-erbB2 were present in 42% of the specimens in cancer cells forming the invasive front. CONCLUSION: The overexpressions, and often co-localizations, of Cox-2, c-Met and beta-catenin in cancer cells forming the invasive front indicate their local interactions and important roles in invasion.

Co-Expression of Cox-2, C-Met and beta-catenin in Cells Forming Invasive front of Gallbladder Cancer / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Gallbladder cancer is a malignancy with poor prognosis, predominantly resulting from invasion and metastasis. Our previous studies have demonstrated that prostaglandin E2 (PGE2), generated by cyclooxygenase 2 (Cox-2), transactivates epidermal growth factor receptor (EGFR), c-Met and beta-catenin; thus, enhancing colon cancer cell growth and invasiveness in vitro. To determine whether these findings are applicable to clinical conditions, we examined the expression and cellular localization/co-localization of Cox-2, c-Met, beta-catenin, EGFR and c-erbB2 in gallbladder cancer. MATERIALS AND METHODS: Thirty-five specimens of invasive gallbladder cancer, 8 in situ carcinoma and 7 adenoma specimens were immunostained with specific antibodies against Cox-2, c-Met, beta-catenin, EGFR and c-erbB2. The cellular distribution, localization and co- localization were examined, and the signal intensities quantified in: a) the central area of gallbladder cancer and b) cancer cells forming the invasive front. RESULTS: Cox-2, c-Met, beta-catenin, c-erbB2 and EGFR were over-expressed in 80, 74, 71, 62 and 11% of invasive gallbladder cancers, respectively. beta-catenin was expressed in 80% of non-malignant specimens, exclusively in the cell membrane, while the cancer specimens showed cytoplasmic and/or nuclear staining. Significantly higher Cox-2, c-Met and beta-catenin expressions were present in cancer cells of the invasive front than in the tumor central areas (p<0.001), and these expressions were significantly (p=0.01) associated with the invasion depth. Co- expressions of Cox-2, c-Met, beta-catenin and c-erbB2 were present in 42% of the specimens in cancer cells forming the invasive front. CONCLUSION: The overexpressions, and often co-localizations, of Cox-2, c-Met and beta-catenin in cancer cells forming the invasive front indicate their local interactions and important roles in invasion.

c-Met Expression in Colorectal Carcinoma and Adenomas: Correlation with Clinicopathologic Parameters

PURPOSE: Hepatocyte growth factor (HGF) stimulates proliferation, migration, and morphogenesis of epithelial cells by specifically binding to its receptor c-met. Abnomalities of the c-met oncogene have been studied in cancers of many organs including thyroid, lung, pancreas, and stomach. However, little is known about the clinical significance of c-met oncogene abnormalities in colorectal carcinomas. In this study, we investigated over- expression of the c-met protein in colorectal adenomas and adenocarcinomas, and analyzed the clinicopathologic significance of this over-expression. METHODS: Expression of the c-met protein localized in colorectal adenoma and adenocarcinoma tissues was analyzed by using immunohistochemistry. The results were compared with clinicopathologic parameters to find clinical correlation. RESULTS: c-met protein was detected in 42.5% (17/40) of colorectal cancers and in 10.0% (4/40) of colorectal adenomas (P= 0.001). In colorectal cancer, the proportion of expression of c-met protein was 0% (0/40) in stage I, 47.6% (10/40) in stage II, 53.8% (7/40) in stage III and, 0% (0/40) in stage IV. c-met protein expression was 18.8% (3/40) in tumors with invasion into the muscularis propria (MP), and 58.3% (14/40) in tumors with invasion beyond the MP. The depth of tumor invasion was a statistically significant factor (P=0.022) for c-met expression. CONCLUSIONS: The c-met protein expression was related to the depth of invasion of colorectal cancer and showed a significant difference in its rate of expression between adenoma and adenocarcinomas.

Significance of expression of c-met protein in gastric carcinoma and its correlation with MVD / 解放军医学杂志

Objective To study the significance of expression of c-met protein in gastric cancer tissue and to explore the correlation between c-met and micro-vessel density (MVD). Methods c-met protein and MVD in gastric cancerous tissue were determined by immunohistochemistry in 47 patients. Results The positive rate of c-met in gastric tissue was 85.1%. The expression of c-met was much higher in patients with tumor diameter larger than 5cm, with deeper invasion, regional lymph nodes metastasis, lymph vessel and venous invasion, and TNM stage Ⅲ-Ⅳ (P

Expression of hepatocyte growth factor receptor in human epiretinal membranes and RPE cells / 中华眼底病杂志

Objective To investigate the expression of hepatocyte growth factor receptor (HGFR) in epiretinal membranes (ERM) of eyes with proliferative vitreoretinopathy (PVR) and cultured retinal pigent epithelium (RPE) cells. Methods Fifteen human epiretinal membranes were obtained from eyes undergone vitrectomy for rhegmatogenous retinal detachment complicated with PVR and observed by immunohistochemical examination to study the expression of HGFR. Using the immunohistochemical technique to evaluate the expression of HGFR in cultured RPE cells. Results In 6 membranes of PVR grade C, HGFR were expressed in 5/6, and 7 cases were detected in 9 membranes of PVR grade D.RPE cells express readily detectable levels of HGFR. Conclusion The findings indicate that HGF might be involved in the formation of epiretinal membranes in PVR.

Expressions of hepatocyte growth factor and its receptor protein in human thyroid neoplasms / 中华内分泌代谢杂志

The expressions of hepatocyte growth factor (HGF) and its receptor (c-Met) protein were examined by immunohistochemistry in benign and malignant thyroid neoplasms.The results showed that the positive rates of HGF and c-Met protein expressions in thyroid carcinomas were significantly higher than those of thyroid adenomas,and especially the expressions of HGF and c-Met proteins in follicular thyroid carcinomas were significantly higher than those in follicular thyroid adenomas.There existed significantly positive correlation between the expression degrees of HGF and c-Met in follicular thyroid carcinoma.Thus,the expressions of HGF and c-Met may be valuable in predicting prognosis of thyroid carcinomas and differentiating benign from malignant thyroid neoplasms.

Expression of hepatocyte growth factor and c-met stimulated by high glucose in human kidney fibroblast and its significance / 中华内分泌代谢杂志

Objective To observe high glucose induced expression of hepatocyte growth factor (HGF) and c met in human kidney fibroblast. Methods The effects of glucose concentrations on expression of HGF, c met and plasminogen activator inhibitor (PAI) 1 in cultured human kidney fibroblasts were observed by RT PCR. In the same system, the effect of exogenous HGF on the expression of PAI 1 was investigated. Results Human kidney fibroblasts cultured in high glucose concentration (25 mmol/L) showed higher HGF and c met expressions in the early stage and then manifested a gradient decrease of HGF and c met expressions, but PAI 1 expression was gradiently increased. Exogenous HGF resulted in inhibiting PAI 1 expression. Conclusion HGF is a potential anti fibrogenic factor and activates matrix degradation pathways in diabetic kidney by reducing PAI 1 expression.