RESUMEN
Histiocytic neoplasms are a heterogeneous group of clonal haematopoietic disorders that are marked by diverse mutations in the mitogen-activated protein kinase (MAPK) pathway1,2. For the 50% of patients with histiocytosis who have BRAFV600 mutations3-5, RAF inhibition is highly efficacious and has markedly altered the natural history of the disease6,7. However, no standard therapy exists for the remaining 50% of patients who lack BRAFV600 mutations. Although ERK dependence has been hypothesized to be a consistent feature across histiocytic neoplasms, this remains clinically unproven and many of the kinase mutations that are found in patients who lack BRAFV600 mutations have not previously been biologically characterized. Here we show ERK dependency in histiocytoses through a proof-of-concept clinical trial of cobimetinib, an oral inhibitor of MEK1 and MEK2, in patients with histiocytoses. Patients were enrolled regardless of their tumour genotype. In parallel, MAPK alterations that were identified in treated patients were characterized for their ability to activate ERK. In the 18 patients that we treated, the overall response rate was 89% (90% confidence interval of 73-100). Responses were durable, with no acquired resistance to date. At one year, 100% of responses were ongoing and 94% of patients remained progression-free. Cobimetinib treatment was efficacious regardless of genotype, and responses were observed in patients with ARAF, BRAF, RAF1, NRAS, KRAS, MEK1 (also known as MAP2K1) and MEK2 (also known as MAP2K2) mutations. Consistent with the observed responses, the characterization of the mutations that we identified in these patients confirmed that the MAPK-pathway mutations were activating. Collectively, these data demonstrate that histiocytic neoplasms are characterized by a notable dependence on MAPK signalling-and that they are consequently responsive to MEK inhibition. These results extend the benefits of molecularly targeted therapy to the entire spectrum of patients with histiocytosis.
Asunto(s)
Azetidinas/uso terapéutico , Trastornos Histiocíticos Malignos/tratamiento farmacológico , Trastornos Histiocíticos Malignos/enzimología , Histiocitosis/tratamiento farmacológico , Histiocitosis/enzimología , Quinasas de Proteína Quinasa Activadas por Mitógenos/antagonistas & inhibidores , Piperidinas/uso terapéutico , Azetidinas/farmacología , Trastornos Histiocíticos Malignos/genética , Trastornos Histiocíticos Malignos/patología , Histiocitosis/genética , Histiocitosis/patología , Humanos , MAP Quinasa Quinasa 1/antagonistas & inhibidores , MAP Quinasa Quinasa 2/antagonistas & inhibidores , MAP Quinasa Quinasa 2/genética , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Mutación , Piperidinas/farmacología , Supervivencia sin Progresión , Proteínas Proto-Oncogénicas B-raf/genética , Proteínas Proto-Oncogénicas c-raf/genéticaRESUMEN
SF3B1 is the most commonly mutated RNA splicing factor in cancer1-4, but the mechanisms by which SF3B1 mutations promote malignancy are poorly understood. Here we integrated pan-cancer splicing analyses with a positive-enrichment CRISPR screen to prioritize splicing alterations that promote tumorigenesis. We report that diverse SF3B1 mutations converge on repression of BRD9, which is a core component of the recently described non-canonical BAF chromatin-remodelling complex that also contains GLTSCR1 and GLTSCR1L5-7. Mutant SF3B1 recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of a poison exon that is derived from an endogenous retroviral element and subsequent degradation of BRD9 mRNA. Depletion of BRD9 causes the loss of non-canonical BAF at CTCF-associated loci and promotes melanomagenesis. BRD9 is a potent tumour suppressor in uveal melanoma, such that correcting mis-splicing of BRD9 in SF3B1-mutant cells using antisense oligonucleotides or CRISPR-directed mutagenesis suppresses tumour growth. Our results implicate the disruption of non-canonical BAF in the diverse cancer types that carry SF3B1 mutations and suggest a mechanism-based therapeutic approach for treating these malignancies.
Asunto(s)
Proteínas Cromosómicas no Histona/metabolismo , Neoplasias/genética , Empalme del ARN , Empalmosomas/metabolismo , Animales , Línea Celular Tumoral , Ensamble y Desensamble de Cromatina/genética , Proteínas Cromosómicas no Histona/genética , Humanos , Ratones , Trasplante de Neoplasias , Neoplasias/patología , Fosfoproteínas/metabolismo , Factores de Empalme de ARN/metabolismo , Empalmosomas/genética , Factores de Transcripción/metabolismoRESUMEN
Although mutations in the gene encoding the RNA splicing factor SF3B1 are frequent in multiple cancers, their functional effects and therapeutic dependencies are poorly understood. Here, we characterize 98 tumors and 12 isogenic cell lines harboring SF3B1 hotspot mutations, identifying hundreds of cryptic 3' splice sites common and specific to different cancer types. Regulatory network analysis revealed that the most common SF3B1 mutation activates MYC via effects conserved across human and mouse cells. SF3B1 mutations promote decay of transcripts encoding the protein phosphatase 2A (PP2A) subunit PPP2R5A, increasing MYC S62 and BCL2 S70 phosphorylation which, in turn, promotes MYC protein stability and impair apoptosis, respectively. Genetic PPP2R5A restoration or pharmacologic PP2A activation impaired SF3B1-mutant tumorigenesis, elucidating a therapeutic approach to aberrant splicing by mutant SF3B1. SIGNIFICANCE: Here, we identify that mutations in SF3B1, the most commonly mutated splicing factor gene across cancers, alter splicing of a specific subunit of the PP2A serine/threonine phosphatase complex to confer post-translational MYC and BCL2 activation, which is therapeutically intervenable using an FDA-approved drug.See related commentary by O'Connor and Narla, p. 765.This article is highlighted in the In This Issue feature, p. 747.
Asunto(s)
Carcinogénesis/genética , Transformación Celular Neoplásica/genética , Neoplasias/genética , Fosfoproteínas/genética , Factores de Empalme de ARN/genética , HumanosRESUMEN
Drug relapse after periods of abstinence is a common feature of substance abuse. Moreover, anxiety and other mood disorders are often co-morbid with substance abuse. Cholinergic receptors in the ventral tegmental area (VTA) are known to mediate drug-seeking and anxiety-related behavior in rodent models. However, it is unclear if overlapping VTA cholinergic mechanisms mediate drug relapse and anxiety-related behaviors associated with drug abstinence. We examined the effects of VTA cholinergic receptor blockade on cue-induced cocaine seeking and anxiety during cocaine abstinence. Male Sprague-Dawley rats were trained to self-administer intravenous cocaine (~0.5â¯mg/kg/infusion, FR1 schedule) for 10â¯days, followed by 14â¯days of forced abstinence. VTA infusion of the non-selective nicotinic acetylcholine receptor antagonist mecamylamine (0, 10, and 30⯵g/side) or the non-selective muscarinic receptor antagonist scopolamine (0, 2.4 and 24⯵g /side) significantly decreased cue-induced cocaine seeking. In cocaine naïve rats, VTA mecamylamine or scopolamine also led to dose-dependent increases in open arm time in the elevated plus maze (EPM). In contrast, rats that received I.V. cocaine, compared to received I.V. saline rats, displayed an anxiogenic response on day 14 of abstinence as reflected by decreased open arm time in the EPM. Furthermore, low doses of VTA mecamylamine (10⯵g /side) or scopolamine (2.4⯵g /side), that did not alter EPM behavior in cocaine naive rats, were sufficient to reverse the anxiogenic effects of cocaine abstinence. Together, these data point to an overlapping role of VTA cholinergic mechanisms to regulate relapse and mood disorder-related responses during cocaine abstinence.
Asunto(s)
Ansiolíticos/farmacología , Ansiedad/tratamiento farmacológico , Antagonistas Colinérgicos/farmacología , Trastornos Relacionados con Cocaína/tratamiento farmacológico , Comportamiento de Búsqueda de Drogas/efectos de los fármacos , Área Tegmental Ventral/efectos de los fármacos , Animales , Ansiedad/metabolismo , Trastornos Relacionados con Cocaína/metabolismo , Trastornos Relacionados con Cocaína/psicología , Modelos Animales de Enfermedad , Comportamiento de Búsqueda de Drogas/fisiología , Quinasa 2 de Adhesión Focal , Masculino , Mecamilamina/farmacología , Ratas Sprague-Dawley , Receptores Colinérgicos/metabolismo , Escopolamina/farmacología , Área Tegmental Ventral/metabolismoRESUMEN
Adult stem and progenitor cells are uniquely capable of self-renewal, and targeting this process represents a potential therapeutic opportunity. The early erythroid progenitor, burst-forming unit erythroid (BFU-E), has substantial self-renewal potential and serves as a key cell type for the treatment of anemias. However, our understanding of mechanisms underlying BFU-E self-renewal is extremely limited. Here, we found that the muscarinic acetylcholine receptor, cholinergic receptor, muscarinic 4 (CHRM4), pathway regulates BFU-E self-renewal and that pharmacological inhibition of CHRM4 corrects anemias of myelodysplastic syndrome (MDS), aging, and hemolysis. Genetic down-regulation of CHRM4 or pharmacologic inhibition of CHRM4 using the selective antagonist PD102807 promoted BFU-E self-renewal, whereas deletion of Chrm4 increased erythroid cell production under stress conditions in vivo. Moreover, muscarinic acetylcholine receptor antagonists corrected anemias in mouse models of MDS, aging, and hemolysis in vivo, extending the survival of mice with MDS relative to that of controls. The effects of muscarinic receptor antagonism on promoting expansion of BFU-Es were mediated by cyclic AMP induction of the transcription factor CREB, whose targets up-regulated key regulators of BFU-E self-renewal. On the basis of these data, we propose a model of hematopoietic progenitor self-renewal through a cholinergic-mediated "hematopoietic reflex" and identify muscarinic acetylcholine receptor antagonists as potential therapies for anemias associated with MDS, aging, and hemolysis.
Asunto(s)
Autorrenovación de las Células , Células Eritroides/citología , Células Eritroides/metabolismo , Receptores Muscarínicos/metabolismo , Células Madre/citología , Anemia/tratamiento farmacológico , Animales , Autorrenovación de las Células/efectos de los fármacos , Autorrenovación de las Células/genética , Eritrocitos/efectos de los fármacos , Eritrocitos/metabolismo , Células Eritroides/efectos de los fármacos , Células Precursoras Eritroides , Eritropoyesis/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Ratones , Ratones Endogámicos C57BL , Antagonistas Muscarínicos/farmacología , Antagonistas Muscarínicos/uso terapéutico , Células Madre/efectos de los fármacos , Células Madre/metabolismoRESUMEN
RNA-binding proteins (RBPs) are essential modulators of transcription and translation frequently dysregulated in cancer. We systematically interrogated RBP dependencies in human cancers using a comprehensive CRISPR/Cas9 domain-focused screen targeting RNA-binding domains of 490 classical RBPs. This uncovered a network of physically interacting RBPs upregulated in acute myeloid leukemia (AML) and crucial for maintaining RNA splicing and AML survival. Genetic or pharmacologic targeting of one key member of this network, RBM39, repressed cassette exon inclusion and promoted intron retention within mRNAs encoding HOXA9 targets as well as in other RBPs preferentially required in AML. The effects of RBM39 loss on splicing further resulted in preferential lethality of spliceosomal mutant AML, providing a strategy for treatment of AML bearing RBP splicing mutations.
Asunto(s)
Redes Reguladoras de Genes , Marcación de Gen/métodos , Leucemia Mieloide Aguda/patología , Proteómica/métodos , Proteínas de Unión al ARN/genética , Regulación hacia Arriba , Empalme Alternativo , Animales , Sistemas CRISPR-Cas , Línea Celular Tumoral , Femenino , Regulación Neoplásica de la Expresión Génica , Células HL-60 , Proteínas de Homeodominio/genética , Humanos , Células Jurkat , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Masculino , Ratones , Trasplante de Neoplasias , Pronóstico , Proteínas de Unión al ARN/metabolismo , Análisis de Secuencia de ARN/métodos , Análisis de SupervivenciaRESUMEN
Altered expression of XPO1, the main nuclear export receptor in eukaryotic cells, has been observed in cancer, and XPO1 has been a focus of anticancer drug development. However, mechanistic evidence for cancer-specific alterations in XPO1 function is lacking. Here, genomic analysis of 42,793 cancers identified recurrent and previously unrecognized mutational hotspots in XPO1. XPO1 mutations exhibited striking lineage specificity, with enrichment in a variety of B-cell malignancies, and introduction of single amino acid substitutions in XPO1 initiated clonal, B-cell malignancy in vivo. Proteomic characterization identified that mutant XPO1 altered the nucleocytoplasmic distribution of hundreds of proteins in a sequence-specific manner that promoted oncogenesis. XPO1 mutations preferentially sensitized cells to inhibitors of nuclear export, providing a biomarker of response to this family of drugs. These data reveal a new class of oncogenic alteration based on change-of-function mutations in nuclear export signal recognition and identify therapeutic targets based on altered nucleocytoplasmic trafficking. SIGNIFICANCE: Here, we identify that heterozygous mutations in the main nuclear exporter in eukaryotic cells, XPO1, are positively selected in cancer and promote the initiation of clonal B-cell malignancies. XPO1 mutations alter nuclear export signal recognition in a sequence-specific manner and sensitize cells to compounds in clinical development inhibiting XPO1 function.This article is highlighted in the In This Issue feature, p. 1325.
Asunto(s)
Transformación Celular Neoplásica , Señales de Exportación Nuclear , Transporte Activo de Núcleo Celular , Animales , Proliferación Celular , Modelos Animales de Enfermedad , Expresión Génica , Genes bcl-2 , Genes myc , Humanos , Carioferinas/química , Carioferinas/genética , Carioferinas/metabolismo , Leucemia de Células B/genética , Leucemia de Células B/metabolismo , Leucemia de Células B/mortalidad , Leucemia de Células B/patología , Ratones , Mutación , Especificidad de Órganos/genética , Unión Proteica , Receptores Citoplasmáticos y Nucleares/química , Receptores Citoplasmáticos y Nucleares/genética , Receptores Citoplasmáticos y Nucleares/metabolismo , Relación Estructura-Actividad , Proteína Exportina 1RESUMEN
Rearrangements involving the neurotrophic receptor kinase genes (NTRK1, NTRK2, and NTRK3; hereafter referred to as TRK) produce oncogenic fusions in a wide variety of cancers in adults and children. Although TRK fusions occur in fewer than 1% of all solid tumors, inhibition of TRK results in profound therapeutic responses, resulting in Breakthrough Therapy FDA approval of the TRK inhibitor larotrectinib for adult and pediatric patients with solid tumors, regardless of histology. In contrast to solid tumors, the frequency of TRK fusions and the clinical effects of targeting TRK in hematologic malignancies are unknown. Here, through an evaluation for TRK fusions across more than 7,000 patients with hematologic malignancies, we identified TRK fusions in acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), histiocytosis, multiple myeloma, and dendritic cell neoplasms. Although TRK fusions occurred in only 0.1% of patients (8 of 7,311 patients), they conferred responsiveness to TRK inhibition in vitro and in vivo in a patient-derived xenograft and a corresponding AML patient with ETV6-NTRK2 fusion. These data identify that despite their individual rarity, collectively, TRK fusions are present in a wide variety of hematologic malignancies and predict clinically significant therapeutic responses to TRK inhibition.