RESUMEN
Germline mutations in ETV6 are associated with a syndrome of thrombocytopenia and leukemia predisposition, and ETV6 is among the most commonly mutated genes in leukemias, especially childhood B-cell acute lymphoblastic leukemia. However, the mechanisms underlying disease caused by ETV6 dysfunction are poorly understood. To address these gaps in knowledge, using CRISPR/Cas9, we developed a mouse model of the most common recurrent, disease-causing germline mutation in ETV6. We found defects in hematopoiesis related primarily to abnormalities of the multipotent progenitor population 4 (MPP4) subset of hematopoietic progenitor cells and evidence of sterile inflammation. Expression of ETV6 in Ba/F3 cells altered the expression of several cytokines, some of which were also detected at higher levels in the bone marrow of the mice with Etv6 mutation. Among these, interleukin-18 and interleukin-13 abrogated B-cell development of sorted MPP4 cells, but not common lymphoid progenitors, suggesting that inflammation contributes to abnormal hematopoiesis by impairing lymphoid development. These data, along with those from humans, support a model in which ETV6 dysfunction promotes inflammation, which adversely affects thrombopoiesis and promotes leukemogenesis.
Asunto(s)
Mutación de Línea Germinal , Leucemia-Linfoma Linfoblástico de Células Precursoras , Proteínas Proto-Oncogénicas c-ets , Animales , Células Germinativas/metabolismo , Humanos , Inflamación/genética , Ratones , Mutación , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Proteínas Proto-Oncogénicas c-ets/genética , Proteínas Represoras/genética , Trombopoyesis , Proteína ETS de Variante de Translocación 6RESUMEN
ETV6 is an ETS family transcription factor that plays a key role in hematopoiesis and megakaryocyte development. Our group and others have identified germline mutations in ETV6 resulting in autosomal dominant thrombocytopenia and predisposition to malignancy; however, molecular mechanisms defining the role of ETV6 in megakaryocyte development have not been well established. Using a combination of molecular, biochemical, and sequencing approaches in patient-derived PBMCs, we demonstrate abnormal cytoplasmic localization of ETV6 and the HDAC3/NCOR2 repressor complex that led to overexpression of HDAC3-regulated interferon response genes. This transcriptional dysregulation was also reflected in patient-derived platelet transcripts and drove aberrant proplatelet formation in megakaryocytes. Our results suggest that aberrant transcription may predispose patients with ETV6 mutations to bone marrow inflammation, dysplasia, and megakaryocyte dysfunction.
Asunto(s)
Enfermedades de la Médula Ósea/patología , Mutación de Línea Germinal , Histona Desacetilasas/metabolismo , Factores Reguladores del Interferón/metabolismo , Co-Represor 2 de Receptor Nuclear/metabolismo , Proteínas Proto-Oncogénicas c-ets/genética , Proteínas Represoras/genética , Trombocitopenia/patología , Enfermedades de la Médula Ósea/etiología , Enfermedades de la Médula Ósea/metabolismo , Niño , Estudios de Cohortes , Predisposición Genética a la Enfermedad , Histona Desacetilasas/genética , Humanos , Factores Reguladores del Interferón/genética , Megacariocitos/metabolismo , Megacariocitos/patología , Co-Represor 2 de Receptor Nuclear/genética , Transporte de Proteínas , Trombocitopenia/etiología , Trombocitopenia/metabolismo , Proteína ETS de Variante de Translocación 6RESUMEN
Single-cell RNA sequencing (scRNA-seq) methods generate sparse gene expression profiles for thousands of single cells in a single experiment. The information in these profiles is sufficient to classify cell types by distinct expression patterns but the high complexity of scRNA-seq libraries often prevents full characterization of transcriptomes from individual cells. To extract more focused gene expression information from scRNA-seq libraries, we developed a strategy to physically recover the DNA molecules comprising transcriptome subsets, enabling deeper interrogation of the isolated molecules by another round of DNA sequencing. We applied the method in cell-centric and gene-centric modes to isolate cDNA fragments from scRNA-seq libraries. First, we resampled the transcriptomes of rare, single megakaryocytes from a complex mixture of lymphocytes and analyzed them in a second round of DNA sequencing, yielding up to 20-fold greater sequencing depth per cell and increasing the number of genes detected per cell from a median of 1313 to 2002. We similarly isolated mRNAs from targeted T cells to improve the reconstruction of their VDJ-rearranged immune receptor mRNAs. Second, we isolated CD3D mRNA fragments expressed across cells in a scRNA-seq library prepared from a clonal T cell line, increasing the number of cells with detected CD3D expression from 59.7% to 100%. Transcriptome resampling is a general approach to recover targeted gene expression information from single-cell RNA sequencing libraries that enhances the utility of these costly experiments, and may be applicable to the targeted recovery of molecules from other single-cell assays.
Asunto(s)
ARN Mensajero/genética , Análisis de Secuencia de ARN/métodos , Análisis de la Célula Individual , Transcriptoma/genética , Animales , Análisis por Conglomerados , ADN Complementario/genética , Perfilación de la Expresión Génica/métodos , Biblioteca de Genes , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Leucocitos Mononucleares/metabolismo , Ratones , Programas InformáticosRESUMEN
FMS-like tyrosine kinase 3-targeted (FLT3-targeted) therapies have shown initial promise for the treatment of acute myeloid leukemia (AML) expressing FLT3-activating mutations; however, resistance emerges rapidly. Furthermore, limited options exist for the treatment of FLT3-independent AML, demonstrating the need for novel therapies that reduce toxicity and improve survival. MERTK receptor tyrosine kinase is overexpressed in 80% to 90% of AMLs and contributes to leukemogenesis. Here, we describe MRX-2843, a type 1 small-molecule tyrosine kinase inhibitor that abrogates activation of both MERTK and FLT3 and their downstream effectors. MRX-2843 treatment induces apoptosis and inhibits colony formation in AML cell lines and primary patient samples expressing MERTK and/or FLT3-ITD, with a wide therapeutic window compared with that of normal human cord blood cells. In murine orthotopic xenograft models, once-daily oral therapy prolonged survival 2- to 3-fold over that of vehicle-treated controls. Additionally, MRX-2843 retained activity against quizartinib-resistant FLT3-ITD-mutant proteins with clinically relevant alterations at the D835 or F691 loci and prolonged survival in xenograft models of quizartinib-resistant AML. Together, these observations validate MRX-2843 as a translational agent and support its clinical development for the treatment of AML.
RESUMEN
Treatment of non-small cell lung cancer (NSCLC) has been transformed by targeted therapies directed against molecular aberrations specifically activated within an individual patient's tumor. However, such therapies are currently only available against a small number of such aberrations, and new targets and therapeutics are needed. Our laboratory has previously identified the MERTK receptor tyrosine kinase (RTK) as a potential drug target in multiple cancer types, including NSCLC. We have recently developed UNC2025--the first-in-class small molecule inhibitor targeting MERTK with pharmacokinetic properties sufficient for clinical translation. Here, we utilize this compound to further validate the important emerging biologic functions of MERTK in lung cancer pathogenesis, to establish that MERTK can be effectively targeted by a clinically translatable agent, and to demonstrate that inhibition of MERTK is a valid treatment strategy in a wide variety of NSCLC lines independent of their driver oncogene status, including in lines with an EGFR mutation, a KRAS/NRAS mutation, an RTK fusion, or another or unknown driver oncogene. Biochemically, we report the selectivity of UNC2025 for MERTK, and its inhibition of oncogenic downstream signaling. Functionally, we demonstrate that UNC2025 induces apoptosis of MERTK-dependent NSCLC cell lines, while decreasing colony formation in vitro and tumor xenograft growth in vivo in murine models. These findings provide further evidence for the importance of MERTK in NSCLC, and demonstrate that MERTK inhibition by UNC2025 is a feasible, clinically relevant treatment strategy in a wide variety of NSCLC subtypes, which warrants further investigation in clinical trials.
Asunto(s)
Antineoplásicos/farmacología , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Oncogenes , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Adenina/análogos & derivados , Adenina/farmacología , Animales , Apoptosis/efectos de los fármacos , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/patología , Línea Celular Tumoral , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/patología , Ratones , Células Madre Neoplásicas/efectos de los fármacos , Células Madre Neoplásicas/metabolismo , Fosforilación , Piperazinas/farmacología , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Proteínas Tirosina Quinasas Receptoras/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Ensayos Antitumor por Modelo de Xenoinjerto , Tirosina Quinasa c-MerRESUMEN
The successes of targeted therapeutics against EGFR and ALK in non-small cell lung cancer (NSCLC) have demonstrated the substantial survival gains made possible by precision therapy. However, the majority of patients do not have tumors with genetic alterations responsive to these therapies, and therefore identification of new targets is needed. Our laboratory previously identified MER receptor tyrosine kinase as one such potential target. We now report our findings targeting MER with a clinically translatable agent--Mer590, a monoclonal antibody specific for MER. Mer590 rapidly and robustly reduced surface and total MER levels in multiple cell lines. Treatment reduced surface MER levels by 87%, and this effect was maximal within four hours. Total MER levels were also dramatically reduced, and this persisted for at least seven days. Mechanistically, MER down-regulation was mediated by receptor internalization and degradation, leading to inhibition of downstream signaling through STAT6, AKT, and ERK1/2. Functionally, this resulted in increased apoptosis, increased chemosensitivity to carboplatin, and decreased colony formation. In addition to carboplatin, Mer590 interacted cooperatively with shRNA-mediated MER inhibition to augment apoptosis. These data demonstrate that MER inhibition can be achieved with a monoclonal antibody in NSCLC. Optimization toward a clinically available anti-MER antibody is warranted.