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Triple‐negative breast cancer (TNBC) is a highly aggressive breast cancer subtype characterized by a remarkable molecular heterogeneity. Currently, there are no effective druggable targets and advanced preclinical models of the human disease. Here, a unique mouse model (MMTV‐R26Met mice) of mammary tumors driven by a subtle increase in the expression of the wild‐type MET receptor is generated. MMTV‐R26Met mice develop spontaneous, exclusive TNBC tumors, recapitulating primary resistance to treatment of patients. Proteomic profiling of MMTV‐R26Met tumors and machine learning approach show that the model faithfully recapitulates intertumoral heterogeneity of human TNBC. Further signaling network analysis highlights potential druggable targets, of which cotargeting of WEE1 and BCL‐XL synergistically kills TNBC cells and efficiently induces tumor regression. Mechanistically, BCL‐XL inhibition exacerbates the dependency of TNBC cells on WEE1 function, leading to Histone H3 and phosphoS33RPA32 upregulation, RRM2 downregulation, cell cycle perturbation, mitotic catastrophe, and apoptosis. This study introduces a unique, powerful mouse model for studying TNBC formation and evolution, its heterogeneity, and for identifying efficient therapeutic targets. [ABSTRACT FROM AUTHOR]

Compelling evidence points to the MET receptor tyrosine kinase as a key player during liver development and regeneration. Recently, a role of MET in the pathophysiology of insulin resistance and obesity is emerging. Herein, we aimed to determine whether MET regulates hepatic insulin sensitivity. To achieve this, mice in which the expression of wild-type MET in hepatocytes is slightly enhanced above endogenous levels (Alb-R26Met mice) were analyzed to document glucose homeostasis, energy balance, and insulin signaling in hepatocytes. We found that Alb-R26Met mice exhibited higher body weight and food intake when compared to R26stopMet control mice. Metabolic analyses revealed that Alb-R26Met mice presented age-related glucose and pyruvate intolerance in comparison to R26stopMet controls. Additionally, in Alb-R26Met mice, high MET levels decreased insulin-induced insulin receptor (IR) and AKT phosphorylation compared to control mice. These results were corroborated in vitro by analyzing IR and AKT phosphorylation in primary mouse hepatocytes from Alb-R26Met and R26stopMet mice upon insulin stimulation. Moreover, co-immunoprecipitation assays revealed MET-IR interaction under both basal and insulin stimulation conditions; this effect was enhanced in Alb-R26Met hepatocytes. Altogether, our results indicate that enhanced MET levels alter hepatic glucose homeostasis, which can be an early event for subsequent liver pathologies. [ABSTRACT FROM AUTHOR]

The development of targeted molecular therapies has provided remarkable advances into the treatment of human cancers. However, in most tumors the selective pressure triggered by anticancer agents encourages cancer cells to acquire resistance mechanisms. The generation of new rationally designed targeting agents acting on the oncogenic path(s) at multiple levels is a promising approach for molecular therapies. 2-phenylimidazo[2,1-b]benzothiazole derivatives have been highlighted for their properties of targeting oncogenic Met receptor tyrosine kinase (RTK) signaling. In this study, we evaluated the mechanism of action of one of the most active imidazo[2,1-b]benzothiazol-2-ylphenyl moiety-based agents, Triflorcas, on a panel of cancer cells with distinct features. We show that Triflorcas impairs in vitro and in vivo tumorigenesis of cancer cells carrying Met mutations. Moreover, Triflorcas hampers survival and anchorage-independent growth of cancer cells characterized by "RTK swapping" by interfering with PDGFRβ phosphorylation. A restrained effect of Triflorcas on metabolic genes correlates with the absence of major side effects in vivo. Mechanistically, in addition to targeting Met, Triflorcas alters phosphorylation levels of the PI3K-Akt pathway, mediating oncogenic dependency to Met, in addition to Retinoblastoma and nucleophosmin/B23, resulting in altered cell cycle progression and mitotic failure. Our findings show how the unusual binding plasticity of the Met active site towards structurally different inhibitors can be exploited to generate drugs able to target Met oncogenic dependency at distinct levels. Moreover, the disease-oriented NCI Anticancer Drug Screen revealed that Triflorcas elicits a unique profile of growth inhibitory-responses on cancer cell lines, indicating a novel mechanism of drug action. The anti-tumor activity elicited by 2-phenylimidazo[2,1-b]benzothiazole derivatives through combined inhibition of distinct effectors in cancer cells reveal them to be promising anticancer agents for further investigation. [ABSTRACT FROM AUTHOR]

Hepatocyte growth factor (HGF) and its receptor MET represent validated targets for cancer therapy. However, HGF/MET inhibitors being explored as cancer therapeutics exhibit cytostatic activity rather than cytotoxic activity, which would be more desired. In this study, we engineered an antagonistic anti-MET antibody that, in addition to blocking HGF/MET signaling, also kills MET-overexpressing cancer cells by antibody-dependent cellular cytotoxicity (ADCC). As a control reagent, we engineered the same antibody in an ADCC-inactive form that is similarly capable of blocking HGF/MET activity, but in the absence of any effector function. In comparing these two antibodies in multiple mouse models of cancer, including HGF-dependent and -independent tumor xenografts, we determined that the ADCC-enhanced antibody was more efficacious than the ADCC-inactive antibody. In orthotopic mammary carcinoma models, ADCC enhancement was crucial to deplete circulating tumor cells and to suppress metastases. Prompted by these results, we optimized the ADCC-enhanced molecule for clinical development, generating an antibody (ARGX-111) with improved pharmacologic properties. ARGX-111 competed with HGF for MET binding, inhibiting ligand-dependent MET activity, downregulated cell surface expression of MET, curbing HGF-independent MET activity, and engaged natural killer cells to kill MET-expressing cancer cells, displaying MET-specific cytotoxic activity. ADCC assays confirmed the cytotoxic effects of ARGX-111 in multiple human cancer cell lines and patient-derived primary tumor specimens, including MET-expressing cancer stem-like cells. Together, our results show how ADCC provides a therapeutic advantage over conventional HGF/MET signaling blockade and generates proof-of-concept for ARGX-111 clinical testing in MET-positive oncologic malignancies. [ABSTRACT FROM AUTHOR]