Mesenchymal-epithelial Transition Factor Expression Research Articles

MiR-200a involvement in the biological behavior of hepatoma carcinoma cells by targeting the regulatory expression of mesenchymal-epithelial transition factor

Objective: To study the regulatory effect of miR-200a on mesenchymal-epithelial transition factor (MET) and its impact on the biological behavior of hepatoma carcinoma cells. Method: A luciferase reporter assay was used to determine miR-200a's regulatory impact on MET. Human hepatoma HepG2 cells were divided into a control group, a miR-200a group, a MET overexpression group, and a co-transfection group (miR-200a+MET). After culture, cell proliferation ability, cell migration ability, apoptosis, cell invasion ability, and the expression of MET and apoptosis-related (Bcl-2, Caspase-3, Bax) proteins were detected and observed by cell counting kit-8 (CCK-8), scratch assay, Annexin V-FITC staining, transwell chambers, and western blotting. The two groups were compared using the independent sample t-test. The multiple groups were statistically analyzed using one-way ANOVA. Results: The luciferase experiment showed that miR-200a had target MET. The proliferation rate, number of invasions in cells (55.00 ± 7.21, 85.00 ± 7.94, 164.67 ± 19.22, 104.00± 12.29), scratch healing rate (28.33% ± 5.03%, 61.67% ± 4.04%, 74.67% ± 7.02%, 49.33% ± 9.02%), and expression levels of MET, Bcl-2, and Caspase-3 proteins were lower in the miR-200a group than those in the control group, MET overexpression group, and co-transfection group, while the MET overexpression group had higher indexes than the other three groups, with statistically significant differences between the groups (P <0.05). The apoptosis rate of HepG2 cells and the expression level of Bax protein were higher in the miR-200a group than those in the control group, MET overexpression group, and co-transfection group (19.25% ± 2.98%, 6.80% ± 1.15%, 3.42% ±0.76%, 9.90% ± 2.72%), while the levels of various indexes in the MIF overexpression group were lower than those in the other three groups. The control group and co-transfection group were between the two groups, and the difference between the groups was statistically significant (P <0.05). Conclusion: HepG2 cell proliferation, migration, invasion, and cell apoptosis induction can be inhibited by miR-200a, and the functional mechanism for this may be associated with the miR-200a target's ability to down-regulate MET expression in HepG2 cells.

Glioma cancer stem cells modulating the local tumor immune environment.

Glioma stem cells (GSCs) drive the resistance mechanism in glioma tumors and mediate the suppression of innate and adaptive immune responses. Here we investigate the expression of mesenchymal-epithelial transition factor (c-Met) and Fas receptor in GSCs and their role in potentiating the tumor-mediated immune suppression through modulation of tumor infiltrating lymphocyte (TIL) population. Tumor tissues were collected from 4 patients who underwent surgery for glioblastoma. GSCs were cultured as neurospheres and evaluated for the co-expression of CD133, c-Met and FasL through flow cytometry. TILs were isolated and evaluated for the lymphocyte subset frequencies including CD3 +, CD4 +, CD8 +, regulatory T cells (FOXP3 + CD25) and microglia (CD11b + CD45) using flow cytometry. Our findings revealed that a significant population of GSCs in all four samples expressed c-Met (89–99%) and FasL (73–97%). A significantly low microglia population was found in local immune cells ranging from 3 to 5%. We did not find a statistically significant correlation between expressions of c-Met + GSC and FasL + GSC with local and systemic immune cells. This may be regarded to the small sample size. The percent c-Met + and FasL + GSC population appeared to be related to percent cytotoxic T cells, regulatory T cells and microglia populations in glioblastoma patients. Further investigation is warranted in a larger sample size.

The Role of HGF/MET Signaling in Metastatic Uveal Melanoma.

Simple SummaryHepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (MET) signaling plays an important role in the metastatic formation and therapeutic resistance to uveal melanoma. Here, we review the various functions of MET signaling contributing to metastatic formation, as well as review resistance to treatments in metastatic uveal melanoma.Hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (MET) signaling promotes tumorigenesis and tumor progression in various types of cancer, including uveal melanoma (UM). The roles of HGF/MET signaling have been studied in cell survival, proliferation, cell motility, and migration. Furthermore, HGF/MET signaling has emerged as a critical player not only in the tumor itself but also in the tumor microenvironment. Expression of MET is frequently observed in metastatic uveal melanoma and is associated with poor prognosis. It has been reported that HGF/MET signaling pathway activation is the major mechanism of treatment resistance in metastatic UM (MUM). To achieve maximal therapeutic benefit in MUM patients, it is important to understand how MET signaling drives cellular functions in uveal melanoma cells. Here, we review the HGF/MET signaling biology and the role of HGF/MET blockades in uveal melanoma.

Helicobacter pylori-induced exosomal MET educates tumour-associated macrophages to promote gastric cancer progression.

Helicobacter pylori (H. pylori) infection triggers chronic inflammation that has been associated with gastric cancer (GC). Exosomes are small extracellular vesicles that have become the key mediators of intercellular communication. In this study, we investigated exosome‐mediated communication between H. pylori‐infected GC cells and macrophages, focusing on the transfer of activated mesenchymal‐epithelial transition factor (MET). We observed a significant decrease in MET protein expression in GC cells after infection with H. pylori, whereas MET mRNA levels remained unchanged. Intriguingly, MET expression, specifically the phosphorylated active form, was increased in exosomes released from H. pylori‐infected GC cells. Confocal microscopy and Western blotting analyses showed that these exosomes containing MET were delivered to and internalized by macrophages. Indeed, in human GC tissues positive for H. pylori, we also observed that activated MET was highly expressed in tumour‐infiltrating macrophages. After internalization, exosomal MET then appeared to educate the macrophages towards a pro‐tumorigenesis phenotype. This included exosomal MET‐mediated stimulation of proinflammatory cytokine secretion IL‐1β, which subsequently promoted tumour growth and progression in vitro and in vivo. Taken together, these data were the first to demonstrate H. pylori infection‐induced upregulation of activated MET in exosomes and the pro‐tumorigenic effect on tumour‐associated macrophages.

The Complete Loss of Tyrosine Kinase Receptors MET and RON Is a Poor Prognostic Factor in Patients with Extrahepatic Cholangiocarcinoma.

Although the survival of patients with cholangiocarcinoma has improved, the prognosis remains unfavorable. The overexpression of mesenchymal-epithelial transition factor (MET) and recepteur d'origine nantais (RON) has been considered to be indicative of a poor prognosis in some types of cancer. On the other hand, some studies have shown that the expression of MET and RON is a favorable prognostic factor in certain types of tumors. Based on the immunohistochemical analysis of MET and RON, 290 patients who underwent resection for extrahepatic cholangiocarcinoma were divided into three groups: MET/RON-negative, -intermediate, and -positive. The associations between MET/RON expression and clinicopathological features, including prognosis, were analyzed. MET/RON-negativity was associated with nodal metastasis and advanced pathological stage. The overall 5-year survival rates were significantly lower in the MET/RON-negative and MET/RON-positive groups than in the MET/RON-intermediate group (28.3%, 32.4% and 48.5%, respectively; p=0.01). The complete loss of one or both MET and RON, as well as their overexpression, is a poor prognostic factor in patients with extrahepatic cholangiocarcinoma, probably due to the high rate of lymph-node metastasis.

Emibetuzumab plus ramucirumab: Simultaneous targeting of MET and VEGFR-2 in patients with advanced hepatocellular cancer in a phase 1b/2 study.

300 Background: The mesenchymal-epithelial transition factor (MET) pathway is upregulated by anti-vascular endothelial growth factor (VEGF) therapies in vivo. Emibetuzumab (E) is a bivalent monoclonal anti-MET antibody that inhibits ligand-dependent and ligand-independent MET signaling. Here we report safety and initial anti-tumor activity for the combination of E plus ramucirumab (R), a human VEGFR-2 antibody in patients (pts) with advanced hepatocellular cancer (HCC) as part of a Phase 1b/2 study (NCT02082210). Methods: Pts with Child Pugh A advanced or metastatic HCC and no further standard therapy available received E (750 mg flat dose) and R (8mg/kg) intravenously every 2 weeks (Q2W) on a 28 day cycle. The primary objective was to evaluate safety and tolerability of the E+R dose and schedule in this patient population. As a co-primary objective, preliminary antitumor activity by RECIST v1.1 was studied. Exploratory objectives included evaluation of biomarkers for MET/HGF and VEGF pathways from fresh pre-treatment tumor biopsies. Results: As of July 2015, 15 pts were treated with E + R in the HCC expansion cohort. Most of the pts had ECOG PS of &lt; 2, and prior sorafenib therapy. Ten pts (67%) experienced ≥ 1 drug-related adverse events (AEs). Commonly related AEs included fatigue (33%), peripheral edema (33%), hypertension (27%), and hypophosphatemia (27%). Most of these events were mild or moderate in severity and the only ≥ grade 3 related events reported included 1 case each of grade 3 fatigue, hypertension, neutropenia, leukopenia, and lymphopenia. In the 9 pts evaluable for response, there were 2 partial responses (PR; 1 unconfirmed, pt still ongoing) and 5 additional pts had stable disease for a disease control rate of 47% (7/15). Six pts were not evaluable and 5 pts remained on treatment at the time of data cut-off. Five pts received 4 or more cycles of therapy, including 1 pt ongoing in cycle 10. Both patients with PR were positive for MET expression. Updated results will be presented at the meeting. Conclusions: The combination of 750 mg E plus 8mg/kg R at Q2W demonstrated an acceptable safety profile and early evidence of antitumor activity in pts with advanced HCC. Clinical trial information: NCT02082210.

Prognostic Value of Hepatocyte Growth Factor Receptor Expression in Patients with Perihilar Cholangiocarcinoma

Although an aggressive surgical approach to perihilar cholangiocarcinoma (PHC) has improved survival, a prognosis of advanced PHC remains unsatisfactory. The overexpression of mesenchymal-epithelial transition factor (MET) and recepteur d'origine nantais (RON) has been shown to be associated with poor prognosis in some types of cancer. One hundred sixty-nine patients who underwent histologically curative resection for PHC were subjected to immunohistochemical analysis for MET and RON. The association between a positive expression of MET or RON and clinicopathologic features as well as the patients' prognosis were analyzed. There were 27 patients (16 %) who had a positive expression for both MET and RON. Although clinicopathologic features in the either MET- or RON-negative group were not significantly different compared to the both MET- and RON-positive group, the prognosis tended to be worse in the patients with both MET and RON positivity. When the analysis was limited to patients with advanced-stage disease (stage III and IVa), a multivariate analysis revealed that both MET and RON positivity and lymph node metastasis were identified as independent poor prognostic factors. The overall survival rate for patients with both MET and RON positivity was worse than that with either MET or RON negativity in patients with advanced PHC. The poor prognosis in these patients was not associated with unfavorable clinicopathologic features. The examination of MET and RON expression in PHC may enable a tailored method for patient classification that could not otherwise be achieved using the conventional pathologic classification system.

Prognostic impact of tumor MET expression among patients with stage IV gastric cancer: A Danish cohort study.

43 Background: Recent clinical trial data indicate poor prognosis for patients with late-stage gastric cancer and positive tumor mesenchymal epithelial transition factor (MET) protein expression. However, there is limited information about the real-world prevalence of MET-positive (-pos) cancers and the associated prognosis. Methods: Using medical registries, we identified a cohort of patients with stage IV gastric cancer in a single institution in Northern Denmark from 2003-2010. From these patients, we collected archived (paraffin-embedded) cancer specimens and analyzed MET protein expression by immunohistochemistry (MET-pos if ≥25% of tumor cells showed membrane staining). We calculated the prevalence of patients with MET-pos tumors. We estimated survival using the Kaplan-Meier method and computed mortality rate ratios comparing MET-pos to MET-negative (-neg) patients using Cox proportional hazards models adjusted for age, gender, and Charlson’s Comorbidity Index (score of 0, 1-2, and 3+). Results: 101 patients with stage IV gastric cancer were included in the study of which 55% had MET-pos tumors. The group of patients with MET-pos tumors were younger at diagnosis than patients with MET-neg tumors (median age 65 vs 68 years), included more men, showed higher comorbidity levels, included more poorly differentiated cancers, and were less likely to undergo surgery or chemotherapy. In patients with MET-pos tumors, one-year survival was 18% compared to 39% in patients with MET-neg tumors (mortality rate ratio=2.3, 95% CI: 1.4-3.9). Conclusions: A large proportion of patients with stage IV gastric cancer had tumors demonstrating MET protein expression, and these patients had poor survival compared with patients without tumor MET expression. [Table: see text]

Tivantinib: A New Promising Mesenchymal–Epithelial Transition Factor Inhibitor in the Treatment of Hepatocellular Carcinoma

Tivantinib (ARQ 197) is an orally administered, selective small molecule that inhibits mesenchymal-epithelial transition factor (MET) via a novel, ATP-independent binding mechanism. Preclinical studies demonstrated that tivantinib has a broad-spectrum anti-tumor activity, especially in cells expressing high levels of MET. A randomized Phase II study in second-line hepatocellular carcinoma showed statistically significant improvement in time to progression with tivantinib compared to a placebo. Noteworthy, a significant pronounced benefit in time to progression and overall survival was observed in MET-high patients. In addition, MET expression was defined as a negative prognostic factor. The most frequent adverse events were hematologic events. A Phase III study in the MET-high hepatocellular carcinoma is actively recruiting patients. Phase II and III studies in non-small-cell lung cancer and colorectal cancer are ongoing.

Cabozantinib in Prostate Cancer: The Beginning of a Precision Paradigm?

The study reported in the article by Smith et al that accompanies this editorial presents data on a novel orally bioavailable tyrosine kinase inhibitor (TKI), cabozantinib, with activity against multiple targets including mesenchymal-epithelial transition factor (MET), also known as hepatocyte growth factor receptor, and the vascular endothelial growth factor receptor 2 (VEGFR2). The authors describe 171 men with castration-resistant prostate cancer (CRPC), a subgroup of patients from a larger phase II randomized discontinuation trial that included multiple tumor types treated with cabozantinib. The trial included a lead-in stage of open-label therapy with cabozantinib and a planned blinded random assignment to cabozantinib or placebo for patients who achieved stable disease at 12 weeks. As reported by the authors, the trial was suspended after 122 patients with CRPC were enrolled onto the open-label portion of the study because of improvements in bone scans and a decrease in pain. At the time the study was halted, a group of 31 patients had been randomly assigned. In this group, there was a marked improvement in the primary end point of progression-free survival (PFS) in the patients receiving cabozantinib compared with placebo (median, 23.9 v 5.9 weeks, respectively; hazard ratio, 0.12; P .001). Although impressive as a small phase II study, the completion of ongoing phase III studies will be critical to confirm the survival benefit. COMET-1, with a primary end point of overall survival, is a placebo-controlled trial of 960 men with CRPC and additional prior therapy randomly assigned to cabozantinib or prednisone (NCT01605227). COMET-2 is a placebo-controlled phase III trial evaluating cabozantinib versus mitoxantrone and prednisone in men with previously treated symptomatic CRPC (NCT01522443), with an emphasis on the effect of cabozantinib on pain and bone disease. Clearly, the results reported by Smith et al support the completion of these larger more definitive studies; perhaps just as important, however, is the need to understand these data as a direction toward more precise multitargeted therapy in prostate cancer. As one potential target in prostate cancer, the understanding of the role of MET, or MET in conjunction with VEGFR, is the subject of ongoing studies. Increased expression of MET protein in tumor cells compared with normal tissue has been associated with tumor grade. An evaluation of the MET ligand hepatocyte growth factor (HGF) in patients from a prior Cancer and Leukemia Group B 9480 study of suramin revealed a correlation between high plasma levels of HGF and decreased patient survival. Studies have also demonstrated that androgen receptor (AR) signaling represses the expression of MET, which supports future studies of targeting the combination of the AR and MET pathways. With the understanding that cabozantinib also inhibits the VEGF pathway, it is of interest that prior laboratory studies have supported the importance of angiogenesis in prostate cancer progression and provide a rationale for combined MET and VEGF pathway inhibition. Additional laboratory studies have demonstrated HGF-mediated angiogenesis through VEGF regulation and an association between VEGF regulation and the activation of c-MET signaling in prostate cancer. Clinical results of antiangiogenic agents alone in prostate cancer, however, have not been optimal, which supports the hypothesis that targeting multiple pathways in addition to VEGF need to be considered to fully influence the complex nature of the tumor microenvironment. In this regard, efforts to understand the effect of agents such as cabozantinib on the MET pathway with additional multitargeted effects such as VEGF inhibition are likely to be important. In fact, there are multiple agents targeting the MET pathway under investigation that have varying degrees of specificity for additional targets. In addition to MET and VEGFR2, cabozantinib has been shown in preclinical models to inhibit RET, KIT, AXL and FLT3 pathways. Cabozantinib has also been demonstrated to have distinct biologic effects on angiogenesis, invasiveness, and metastasis in animal models, as would be expected from these molecular targets. Other MET pathway–focused therapeutic approaches under investigation include antibodies against HGF such as rilotumumab (which is being evaluated in lung, gastric, and gynecologic malignancies) and antibodies against MET such as onartuzumab (which is being evaluated in a phase III trial in combination with erlotinib v erlotinib alone in patients with MET-positive non–small-cell lung carcinoma [NSCLC; NCT01456325]). Receptor TKIs targeting MET are under investigation and include nonselective TKIs such as cabozantinib (as studied in the clinical trial by Smith et al), crizotinib (which targets MET as well as ALK and is approved for the treatment of EML4-ALK positive NSCLC), and foretinib (which inhibits c-MET, VEGFR2, PDGFR, and KIT). More target-selective MET TKIs are also under investigation including agents such as tivantinib (ARQ197; Arqule, Woburn, MA), EMD 1214063 (EMD Serono, Darmstadt, Germany), EMD 1204831 (EMD Serono), AMG 337 (Amgen, Thousand Oaks, CA), and INCB028060 (Incyte, Wilmington, DE). JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 31 NUMBER 4 FEBRUARY 1 2013

MicroRNA‐34b functions as a potential tumor suppressor in endometrial serous adenocarcinoma

Endometrial serous adenocarcinoma (ESC) is aggressive and carries a poor prognosis. p53 is frequently mutated in ESC. microRNAs (miRNAs) are a direct p53 target and have been implicated in cancer cell behavior. In this study, we compared miRNA expression levels in ESC with the levels in endometrial endometrioid adenocarcinoma (EEC) and normal endometria. Six miRNAs were identified as having aberrant down-regulation specific to ESC with miR-34b being most pronounced. miR-34b was found to have promoter hypermethylation, which when reversed, restored miR-34b expression in the cell lines treated with 5-aza-2' deoxycytidine (DAC). Ectopic expression of miR-34b in turn inhibited cell growth, migration and most notably invasion. Our findings suggest a relationship among p53 mutation, miR-34b promoter methylation and tumor cell behavior. These effects are likely mediated by the downstream target of miR-34b, the proto-oncogene mesenchymal-epithelial transition factor (MET), a known prognostic factor in endometrial carcinomas. The expression of MET was reduced following the restoration of miR-34b in cell lines. In summary, our data suggest that miR-34b plays a role in the molecular pathogenesis of endometrial cancer.

Epidermal growth factor and hepatocyte growth factor receptors collaborate to induce multiple biological responses in bovine mammary epithelial cells

The aim of this work was to explore whether epidermal growth factor (EGF) and hepatocyte growth factor (HGF) could increase the biological responses of a mammary epithelial cell line of bovine origin when added simultaneously. We also investigated a possible molecular mechanism underlying this cooperation. The development of mammary gland requires several circulating and locally produced hormones. Hepatocyte growth factor and its tyrosine kinase receptor, mesenchymal-epithelial transition factor (MET), are expressed and temporally regulated during mammary development and differentiation. Epidermal growth factor receptor and its ligands have also been implicated in the growth and morphogenesis of the mammary epithelium. Both EGF and HGF seem to exert a morphogenic program in this tissue; therefore, we hypothesized that these cytokines could act cooperatively in bovine mammary epithelial cells. We have already shown that the bovine BME-UV cell line, a nontumorigenic mammary epithelial line, expresses both MET and EGF receptor. Simultaneous treatment with HGF and EGF elicited an increase in proliferation, dispersion, degradation of extracellular matrix, and motility. Following EGF treatment, BME-UV mammary cells exhibited an increase in MET expression at both the mRNA and protein levels. Long-term treatment of BME-UV cells with HGF and EGF together increased the level of activation of the extracellular signal-regulated kinase 1/2 and protein kinase B signaling pathways when compared with HGF or EGF alone. These data outline a possible cooperative role of the EGF and HGF pathways and indicate that cross-talk between their respective receptors may modulate mammary gland development in the cow.