RESUMEN
During the germinal center (GC) reaction, B cells undergo extensive redistribution of cohesin complex and three-dimensional reorganization of their genomes. Yet, the significance of cohesin and architectural programming in the humoral immune response is unknown. Herein we report that homozygous deletion of Smc3, encoding the cohesin ATPase subunit, abrogated GC formation, while, in marked contrast, Smc3 haploinsufficiency resulted in GC hyperplasia, skewing of GC polarity and impaired plasma cell (PC) differentiation. Genome-wide chromosomal conformation and transcriptional profiling revealed defects in GC B cell terminal differentiation programs controlled by the lymphoma epigenetic tumor suppressors Tet2 and Kmt2d and failure of Smc3-haploinsufficient GC B cells to switch from B cell- to PC-defining transcription factors. Smc3 haploinsufficiency preferentially impaired the connectivity of enhancer elements controlling various lymphoma tumor suppressor genes, and, accordingly, Smc3 haploinsufficiency accelerated lymphomagenesis in mice with constitutive Bcl6 expression. Collectively, our data indicate a dose-dependent function for cohesin in humoral immunity to facilitate the B cell to PC phenotypic switch while restricting malignant transformation.
Asunto(s)
Linfocitos B/metabolismo , Proteínas de Ciclo Celular/deficiencia , Proteínas de Ciclo Celular/genética , Transformación Celular Neoplásica/genética , Proteoglicanos Tipo Condroitín Sulfato/genética , Proteínas Cromosómicas no Histona/deficiencia , Proteínas Cromosómicas no Histona/genética , Dosificación de Gen , Centro Germinal/metabolismo , Inmunidad Humoral , Linfoma de Células B/genética , Animales , Linfocitos B/inmunología , Linfocitos B/patología , Proteínas de Ciclo Celular/metabolismo , Diferenciación Celular , Proliferación Celular , Transformación Celular Neoplásica/inmunología , Transformación Celular Neoplásica/metabolismo , Transformación Celular Neoplásica/patología , Células Cultivadas , Proteoglicanos Tipo Condroitín Sulfato/deficiencia , Proteoglicanos Tipo Condroitín Sulfato/metabolismo , Proteínas Cromosómicas no Histona/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Dioxigenasas , Eliminación de Gen , Regulación Neoplásica de la Expresión Génica , Centro Germinal/inmunología , Centro Germinal/patología , Haploinsuficiencia , N-Metiltransferasa de Histona-Lisina/genética , N-Metiltransferasa de Histona-Lisina/metabolismo , Humanos , Linfoma de Células B/inmunología , Linfoma de Células B/metabolismo , Linfoma de Células B/patología , Linfoma de Células B Grandes Difuso/genética , Linfoma de Células B Grandes Difuso/inmunología , Linfoma de Células B Grandes Difuso/metabolismo , Linfoma de Células B Grandes Difuso/patología , Ratones Endogámicos C57BL , Ratones Noqueados , Proteína de la Leucemia Mieloide-Linfoide/genética , Proteína de la Leucemia Mieloide-Linfoide/metabolismo , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Transducción de Señal , CohesinasRESUMEN
CKIα ablation induces p53 activation, and CKIα degradation underlies the therapeutic effect of lenalidomide in a pre-leukemia syndrome. Here we describe the development of CKIα inhibitors, which co-target the transcriptional kinases CDK7 and CDK9, thereby augmenting CKIα-induced p53 activation and its anti-leukemic activity. Oncogene-driving super-enhancers (SEs) are highly sensitive to CDK7/9 inhibition. We identified multiple newly gained SEs in primary mouse acute myeloid leukemia (AML) cells and demonstrate that the inhibitors abolish many SEs and preferentially suppress the transcription elongation of SE-driven oncogenes. We show that blocking CKIα together with CDK7 and/or CDK9 synergistically stabilize p53, deprive leukemia cells of survival and proliferation-maintaining SE-driven oncogenes, and induce apoptosis. Leukemia progenitors are selectively eliminated by the inhibitors, explaining their therapeutic efficacy with preserved hematopoiesis and leukemia cure potential; they eradicate leukemia in MLL-AF9 and Tet2-/-;Flt3ITD AML mouse models and in several patient-derived AML xenograft models, supporting their potential efficacy in curing human leukemia.
Asunto(s)
Caseína Quinasa Ialfa/antagonistas & inhibidores , Leucemia Mieloide Aguda/tratamiento farmacológico , Animales , Apoptosis/efectos de los fármacos , Caseína Quinasa Ialfa/fisiología , Proliferación Celular/efectos de los fármacos , Quinasa 9 Dependiente de la Ciclina/antagonistas & inhibidores , Quinasa 9 Dependiente de la Ciclina/fisiología , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Quinasas Ciclina-Dependientes/fisiología , Proteínas de Unión al ADN , Modelos Animales de Enfermedad , Elementos de Facilitación Genéticos/genética , Hematopoyesis , Humanos , Ratones , Ratones Endogámicos C57BL , Proteínas de Fusión Oncogénica/metabolismo , Proteínas Serina-Treonina Quinasas , Proteínas Proto-Oncogénicas , Proteína p53 Supresora de Tumor/fisiología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
In somatic tissue differentiation, chromatin accessibility changes govern priming and precursor commitment towards cellular fates1-3. Therefore, somatic mutations are likely to alter chromatin accessibility patterns, as they disrupt differentiation topologies leading to abnormal clonal outgrowth. However, defining the impact of somatic mutations on the epigenome in human samples is challenging due to admixed mutated and wild-type cells. Here, to chart how somatic mutations disrupt epigenetic landscapes in human clonal outgrowths, we developed genotyping of targeted loci with single-cell chromatin accessibility (GoT-ChA). This high-throughput platform links genotypes to chromatin accessibility at single-cell resolution across thousands of cells within a single assay. We applied GoT-ChA to CD34+ cells from patients with myeloproliferative neoplasms with JAK2V617F-mutated haematopoiesis. Differential accessibility analysis between wild-type and JAK2V617F-mutant progenitors revealed both cell-intrinsic and cell-state-specific shifts within mutant haematopoietic precursors, including cell-intrinsic pro-inflammatory signatures in haematopoietic stem cells, and a distinct profibrotic inflammatory chromatin landscape in megakaryocytic progenitors. Integration of mitochondrial genome profiling and cell-surface protein expression measurement allowed expansion of genotyping onto DOGMA-seq through imputation, enabling single-cell capture of genotypes, chromatin accessibility, RNA expression and cell-surface protein expression. Collectively, we show that the JAK2V617F mutation leads to epigenetic rewiring in a cell-intrinsic and cell type-specific manner, influencing inflammation states and differentiation trajectories. We envision that GoT-ChA will empower broad future investigations of the critical link between somatic mutations and epigenetic alterations across clonal populations in malignant and non-malignant contexts.
Asunto(s)
Cromatina , Epigénesis Genética , Genotipo , Mutación , Análisis de la Célula Individual , Animales , Femenino , Humanos , Masculino , Ratones , Antígenos CD34/metabolismo , Diferenciación Celular/genética , Cromatina/química , Cromatina/genética , Cromatina/metabolismo , Epigénesis Genética/genética , Epigenoma/genética , Genoma Mitocondrial/genética , Técnicas de Genotipaje , Hematopoyesis/genética , Células Madre Hematopoyéticas/metabolismo , Células Madre Hematopoyéticas/patología , Inflamación/genética , Inflamación/patología , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismo , Megacariocitos/metabolismo , Megacariocitos/patología , Proteínas de la Membrana/genética , Trastornos Mieloproliferativos/genética , Trastornos Mieloproliferativos/metabolismo , Trastornos Mieloproliferativos/patología , ARN/genética , Células Clonales/metabolismoRESUMEN
Chromatin-binding proteins are critical regulators of cell state in haematopoiesis1,2. Acute leukaemias driven by rearrangement of the mixed lineage leukaemia 1 gene (KMT2Ar) or mutation of the nucleophosmin gene (NPM1) require the chromatin adapter protein menin, encoded by the MEN1 gene, to sustain aberrant leukaemogenic gene expression programs3-5. In a phase 1 first-in-human clinical trial, the menin inhibitor revumenib, which is designed to disrupt the menin-MLL1 interaction, induced clinical responses in patients with leukaemia with KMT2Ar or mutated NPM1 (ref. 6). Here we identified somatic mutations in MEN1 at the revumenib-menin interface in patients with acquired resistance to menin inhibition. Consistent with the genetic data in patients, inhibitor-menin interface mutations represent a conserved mechanism of therapeutic resistance in xenograft models and in an unbiased base-editor screen. These mutants attenuate drug-target binding by generating structural perturbations that impact small-molecule binding but not the interaction with the natural ligand MLL1, and prevent inhibitor-induced eviction of menin and MLL1 from chromatin. To our knowledge, this study is the first to demonstrate that a chromatin-targeting therapeutic drug exerts sufficient selection pressure in patients to drive the evolution of escape mutants that lead to sustained chromatin occupancy, suggesting a common mechanism of therapeutic resistance.
Asunto(s)
Resistencia a Antineoplásicos , Leucemia , Mutación , Proteínas Proto-Oncogénicas , Animales , Humanos , Antineoplásicos/química , Antineoplásicos/metabolismo , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Sitios de Unión/efectos de los fármacos , Sitios de Unión/genética , Cromatina/genética , Cromatina/metabolismo , Resistencia a Antineoplásicos/genética , Leucemia/tratamiento farmacológico , Leucemia/genética , Leucemia/metabolismo , Unión Proteica/efectos de los fármacos , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Proteínas Proto-Oncogénicas/química , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismoRESUMEN
Riedel et al. (2021) show that expression of MN1 is capable of blocking myeloid differentiation and initiating leukemia through mechanisms that require Brg1-containing chromatin remodeling complexes. Intriguingly, this process depends on an unstructured polyglutamine repeat region within MN1.
Asunto(s)
Leucemia Mieloide Aguda , Neoplasias Meníngeas , Meningioma , Humanos , Transactivadores , Proteínas Supresoras de TumorRESUMEN
Mutant isocitrate dehydrogenase (IDH) 1 and 2 play a pathogenic role in cancers, including acute myeloid leukemia (AML), by producing oncometabolite 2-hydroxyglutarate (2-HG). We recently reported that tyrosine phosphorylation activates IDH1 R132H mutant in AML cells. Here, we show that mutant IDH2 (mIDH2) R140Q commonly has K413 acetylation, which negatively regulates mIDH2 activity in human AML cells by attenuating dimerization and blocking binding of substrate (α-ketoglutarate) and cofactor (NADPH). Mechanistically, K413 acetylation of mitochondrial mIDH2 is achieved through a series of hierarchical phosphorylation events mediated by tyrosine kinase FLT3, which phosphorylates mIDH2 to recruit upstream mitochondrial acetyltransferase ACAT1 and simultaneously activates ACAT1 and inhibits upstream mitochondrial deacetylase SIRT3 through tyrosine phosphorylation. Moreover, we found that the intrinsic enzyme activity of mIDH2 is much higher than mIDH1, thus the inhibitory K413 acetylation optimizes leukemogenic ability of mIDH2 in AML cells by both producing sufficient 2-HG for transformation and avoiding cytotoxic accumulation of intracellular 2-HG.
Asunto(s)
Isocitrato Deshidrogenasa/genética , Leucemia Mieloide Aguda/metabolismo , Acetil-CoA C-Acetiltransferasa/metabolismo , Acetilación , Animales , Antineoplásicos/farmacología , Femenino , Humanos , Isocitrato Deshidrogenasa/metabolismo , Ácidos Cetoglutáricos/metabolismo , Leucemia Mieloide Aguda/genética , Lisina/genética , Lisina/metabolismo , Masculino , Ratones , Ratones Endogámicos NOD , Mutación/genética , NADP/metabolismo , Proteínas Nucleares/metabolismo , Fosforilación , Polimorfismo de Nucleótido Simple/genética , Cultivo Primario de Células , Unión Proteica , Procesamiento Proteico-Postraduccional , Proteínas Tirosina Quinasas/metabolismoRESUMEN
Acute myeloid leukaemia (AML) represents a set of heterogeneous myeloid malignancies, and hallmarks include mutations in epigenetic modifiers, transcription factors and kinases1-5. The extent to which mutations in AML drive alterations in chromatin 3D structure and contribute to myeloid transformation is unclear. Here we use Hi-C and whole-genome sequencing to analyse 25 samples from patients with AML and 7 samples from healthy donors. Recurrent and subtype-specific alterations in A/B compartments, topologically associating domains and chromatin loops were identified. RNA sequencing, ATAC with sequencing and CUT&Tag for CTCF, H3K27ac and H3K27me3 in the same AML samples also revealed extensive and recurrent AML-specific promoter-enhancer and promoter-silencer loops. We validated the role of repressive loops on their target genes by CRISPR deletion and interference. Structural variation-induced enhancer-hijacking and silencer-hijacking events were further identified in AML samples. Hijacked enhancers play a part in AML cell growth, as demonstrated by CRISPR screening, whereas hijacked silencers have a downregulating role, as evidenced by CRISPR-interference-mediated de-repression. Finally, whole-genome bisulfite sequencing of 20 AML and normal samples revealed the delicate relationship between DNA methylation, CTCF binding and 3D genome structure. Treatment of AML cells with a DNA hypomethylating agent and triple knockdown of DNMT1, DNMT3A and DNMT3B enabled the manipulation of DNA methylation to revert 3D genome organization and gene expression. Overall, this study provides a resource for leukaemia studies and highlights the role of repressive loops and hijacked cis elements in human diseases.
Asunto(s)
Genoma Humano , Leucemia Mieloide Aguda , Humanos , Cromatina/genética , Metilación de ADN , Leucemia Mieloide Aguda/genética , Genoma Humano/genética , Regiones Promotoras Genéticas , Elementos de Facilitación Genéticos , Silenciador del Gen , Reproducibilidad de los Resultados , Sistemas CRISPR-Cas , Análisis de Secuencia , ADN (Citosina-5-)-Metiltransferasas , Regulación Leucémica de la Expresión GénicaRESUMEN
Clonal haematopoiesis, which is highly prevalent in older individuals, arises from somatic mutations that endow a proliferative advantage to haematopoietic cells. Clonal haematopoiesis increases the risk of myocardial infarction and stroke independently of traditional risk factors1. Among the common genetic variants that give rise to clonal haematopoiesis, the JAK2V617F (JAK2VF) mutation, which increases JAK-STAT signalling, occurs at a younger age and imparts the strongest risk of premature coronary heart disease1,2. Here we show increased proliferation of macrophages and prominent formation of necrotic cores in atherosclerotic lesions in mice that express Jak2VF selectively in macrophages, and in chimeric mice that model clonal haematopoiesis. Deletion of the essential inflammasome components caspase 1 and 11, or of the pyroptosis executioner gasdermin D, reversed these adverse changes. Jak2VF lesions showed increased expression of AIM2, oxidative DNA damage and DNA replication stress, and Aim2 deficiency reduced atherosclerosis. Single-cell RNA sequencing analysis of Jak2VF lesions revealed a landscape that was enriched for inflammatory myeloid cells, which were suppressed by deletion of Gsdmd. Inhibition of the inflammasome product interleukin-1ß reduced macrophage proliferation and necrotic formation while increasing the thickness of fibrous caps, indicating that it stabilized plaques. Our findings suggest that increased proliferation and glycolytic metabolism in Jak2VF macrophages lead to DNA replication stress and activation of the AIM2 inflammasome, thereby aggravating atherosclerosis. Precise application of therapies that target interleukin-1ß or specific inflammasomes according to clonal haematopoiesis status could substantially reduce cardiovascular risk.
Asunto(s)
Aterosclerosis/patología , Hematopoyesis Clonal , Proteínas de Unión al ADN/metabolismo , Inflamasomas/metabolismo , Animales , Anticuerpos/inmunología , Anticuerpos/uso terapéutico , Aterosclerosis/tratamiento farmacológico , Aterosclerosis/inmunología , Médula Ósea/metabolismo , Caspasa 1/metabolismo , Caspasas Iniciadoras/metabolismo , Modelos Animales de Enfermedad , Femenino , Humanos , Inflamación/metabolismo , Inflamación/patología , Proteína Antagonista del Receptor de Interleucina 1/farmacología , Proteína Antagonista del Receptor de Interleucina 1/uso terapéutico , Interleucina-1beta/inmunología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismo , Macrófagos/patología , Ratones , Ratones Endogámicos C57BL , Proteínas de Unión a Fosfato/metabolismo , Piroptosis , RNA-Seq , Análisis de la Célula IndividualRESUMEN
The European LeukemiaNet (ELN) genetic risk classifications were developed based on data from younger adults receiving intensive chemotherapy. Emerging analyses from patients receiving less-intensive therapies prompted a proposal for an ELN genetic risk classification specifically for this patient population.
RESUMEN
Myeloid malignancies, including acute myeloid leukaemia (AML), arise from the expansion of haematopoietic stem and progenitor cells that acquire somatic mutations. Bulk molecular profiling has suggested that mutations are acquired in a stepwise fashion: mutant genes with high variant allele frequencies appear early in leukaemogenesis, and mutations with lower variant allele frequencies are thought to be acquired later1-3. Although bulk sequencing can provide information about leukaemia biology and prognosis, it cannot distinguish which mutations occur in the same clone(s), accurately measure clonal complexity, or definitively elucidate the order of mutations. To delineate the clonal framework of myeloid malignancies, we performed single-cell mutational profiling on 146 samples from 123 patients. Here we show that AML is dominated by a small number of clones, which frequently harbour co-occurring mutations in epigenetic regulators. Conversely, mutations in signalling genes often occur more than once in distinct subclones, consistent with increasing clonal diversity. We mapped clonal trajectories for each sample and uncovered combinations of mutations that synergized to promote clonal expansion and dominance. Finally, we combined protein expression with mutational analysis to map somatic genotype and clonal architecture with immunophenotype. Our findings provide insights into the pathogenesis of myeloid transformation and how clonal complexity evolves with disease progression.
Asunto(s)
Células Clonales/patología , Análisis Mutacional de ADN , Mutación , Trastornos Mieloproliferativos/genética , Trastornos Mieloproliferativos/patología , Análisis de la Célula Individual , Separación Celular , Células Clonales/metabolismo , Humanos , InmunofenotipificaciónRESUMEN
Mutations in IDH1, IDH2, and TET2 are recurrently observed in myeloid neoplasms. IDH1 and IDH2 encode isocitrate dehydrogenase isoforms, which normally catalyze the conversion of isocitrate to α-ketoglutarate (α-KG). Oncogenic IDH1/2 mutations confer neomorphic activity, leading to the production of D-2-hydroxyglutarate (D-2-HG), a potent inhibitor of α-KG-dependent enzymes which include the TET methylcytosine dioxygenases. Given their mutual exclusivity in myeloid neoplasms, IDH1, IDH2, and TET2 mutations may converge on a common oncogenic mechanism. Contrary to this expectation, we observed that they have distinct, and even opposite, effects on hematopoietic stem and progenitor cells in genetically engineered mice. Epigenetic and single-cell transcriptomic analyses revealed that Idh2R172K and Tet2 loss-of-function have divergent consequences on the expression and activity of key hematopoietic and leukemogenic regulators. Notably, chromatin accessibility and transcriptional deregulation in Idh2R172K cells were partially disconnected from DNA methylation alterations. These results highlight unanticipated divergent effects of IDH1/2 and TET2 mutations, providing support for the optimization of genotype-specific therapies.
Asunto(s)
Proteínas de Unión al ADN , Dioxigenasas , Isocitrato Deshidrogenasa , Células Madre , Animales , Ratones , Dioxigenasas/genética , Proteínas de Unión al ADN/genética , Isocitrato Deshidrogenasa/genética , Isocitrato Deshidrogenasa/metabolismo , Ácidos Cetoglutáricos/metabolismo , Mutación , Neoplasias , Células Madre/metabolismoRESUMEN
Glioblastoma is the most frequently occurring and invariably fatal primary brain tumor in adults. The vast majority of glioblastomas is characterized by chromosomal copy number alterations, including gain of whole chromosome 7 and loss of whole chromosome 10. Gain of whole chromosome 7 is an early event in gliomagenesis that occurs in proneural-like precursor cells, which give rise to all isocitrate dehydrogenase (IDH) wild-type glioblastoma transcriptional subtypes. Platelet-derived growth factor A (PDGFA) is one gene on chromosome 7 known to drive gliomagenesis, but, given its location near the end of 7p, there are likely several other genes located along chromosome 7 that select for its increased whole-chromosome copy number within glioblastoma cells. To identify other potential genes that could select for gain of whole chromosome 7, we developed an unbiased bioinformatics approach that identified homeobox A5 (HOXA5) as a gene whose expression correlated with gain of chromosome 7 and a more aggressive phenotype of the resulting glioma. High expression of HOXA5 in glioblastoma was associated with a proneural gene expression pattern and decreased overall survival in both human proneural and PDGF-driven mouse glioblastoma. Furthermore, HOXA5 overexpression promoted cellular proliferation and potentiated radioresistance. We also found enrichment of HOXA5 expression in recurrent human and mouse glioblastoma at first recurrence after radiotherapy. Overall, this study implicates HOXA5 as a chromosome 7-associated gene-level locus that promotes selection for gain of whole chromosome 7 and an aggressive phenotype in glioblastoma.
Asunto(s)
Neoplasias Encefálicas/genética , Cromosomas Humanos Par 7 , Glioblastoma/genética , Proteínas de Homeodominio/metabolismo , Fosfoproteínas/metabolismo , Animales , Neoplasias Encefálicas/mortalidad , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/radioterapia , Proliferación Celular , Duplicación Cromosómica , Glioblastoma/mortalidad , Glioblastoma/patología , Glioblastoma/radioterapia , Proteínas de Homeodominio/genética , Humanos , Isocitrato Deshidrogenasa/genética , Ratones , Recurrencia Local de Neoplasia , Fosfoproteínas/genética , Tolerancia a Radiación , Factores de TranscripciónRESUMEN
Leukemia cells accumulate DNA damage, but altered DNA repair mechanisms protect them from apoptosis. We showed here that formaldehyde generated by serine/1-carbon cycle metabolism contributed to the accumulation of toxic DNA-protein crosslinks (DPCs) in leukemia cells, especially in driver clones harboring oncogenic tyrosine kinases (OTKs: FLT3(internal tandem duplication [ITD]), JAK2(V617F), BCR-ABL1). To counteract this effect, OTKs enhanced the expression of DNA polymerase theta (POLθ) via ERK1/2 serine/threonine kinase-dependent inhibition of c-CBL E3 ligase-mediated ubiquitination of POLθ and its proteasomal degradation. Overexpression of POLθ in OTK-positive cells resulted in the efficient repair of DPC-containing DNA double-strand breaks by POLθ-mediated end-joining. The transforming activities of OTKs and other leukemia-inducing oncogenes, especially of those causing the inhibition of BRCA1/2-mediated homologous recombination with and without concomitant inhibition of DNA-PK-dependent nonhomologous end-joining, was abrogated in Polq-/- murine bone marrow cells. Genetic and pharmacological targeting of POLθ polymerase and helicase activities revealed that both activities are promising targets in leukemia cells. Moreover, OTK inhibitors or DPC-inducing drug etoposide enhanced the antileukemia effect of POLθ inhibitor in vitro and in vivo. In conclusion, we demonstrated that POLθ plays an essential role in protecting leukemia cells from metabolically induced toxic DNA lesions triggered by formaldehyde, and it can be targeted to achieve a therapeutic effect.
Asunto(s)
Proteína BRCA1 , Daño del ADN , Leucemia , Animales , Ratones , Proteína BRCA2 , ADN/metabolismo , Leucemia/enzimología , Leucemia/genética , ADN Polimerasa thetaRESUMEN
Proinflammatory signaling is a hallmark feature of human cancer, including in myeloproliferative neoplasms (MPNs), most notably myelofibrosis (MF). Dysregulated inflammatory signaling contributes to fibrotic progression in MF; however, the individual cytokine mediators elicited by malignant MPN cells to promote collagen-producing fibrosis and disease evolution are yet to be fully elucidated. Previously, we identified a critical role for combined constitutive JAK/STAT and aberrant NF-κB proinflammatory signaling in MF development. Using single-cell transcriptional and cytokine-secretion studies of primary cells from patients with MF and the human MPLW515L (hMPLW515L) murine model of MF, we extend our previous work and delineate the role of CXCL8/CXCR2 signaling in MF pathogenesis and bone marrow fibrosis progression. Hematopoietic stem/progenitor cells from patients with MF are enriched for a CXCL8/CXCR2 gene signature and display enhanced proliferation and fitness in response to an exogenous CXCL8 ligand in vitro. Genetic deletion of Cxcr2 in the hMPLW515L-adoptive transfer model abrogates fibrosis and extends overall survival, and pharmacologic inhibition of the CXCR1/2 pathway improves hematologic parameters, attenuates bone marrow fibrosis, and synergizes with JAK inhibitor therapy. Our mechanistic insights provide a rationale for therapeutic targeting of the CXCL8/CXCR2 pathway among patients with MF.
Asunto(s)
Trastornos Mieloproliferativos , Neoplasias , Mielofibrosis Primaria , Humanos , Ratones , Animales , Mielofibrosis Primaria/patología , Trastornos Mieloproliferativos/genética , Transducción de Señal , Neoplasias/complicaciones , Citocinas/metabolismo , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismoRESUMEN
Transcription and pre-mRNA splicing are key steps in the control of gene expression and mutations in genes regulating each of these processes are common in leukaemia1,2. Despite the frequent overlap of mutations affecting epigenetic regulation and splicing in leukaemia, how these processes influence one another to promote leukaemogenesis is not understood and, to our knowledge, there is no functional evidence that mutations in RNA splicing factors initiate leukaemia. Here, through analyses of transcriptomes from 982 patients with acute myeloid leukaemia, we identified frequent overlap of mutations in IDH2 and SRSF2 that together promote leukaemogenesis through coordinated effects on the epigenome and RNA splicing. Whereas mutations in either IDH2 or SRSF2 imparted distinct splicing changes, co-expression of mutant IDH2 altered the splicing effects of mutant SRSF2 and resulted in more profound splicing changes than either mutation alone. Consistent with this, co-expression of mutant IDH2 and SRSF2 resulted in lethal myelodysplasia with proliferative features in vivo and enhanced self-renewal in a manner not observed with either mutation alone. IDH2 and SRSF2 double-mutant cells exhibited aberrant splicing and reduced expression of INTS3, a member of the integrator complex3, concordant with increased stalling of RNA polymerase II (RNAPII). Aberrant INTS3 splicing contributed to leukaemogenesis in concert with mutant IDH2 and was dependent on mutant SRSF2 binding to cis elements in INTS3 mRNA and increased DNA methylation of INTS3. These data identify a pathogenic crosstalk between altered epigenetic state and splicing in a subset of leukaemias, provide functional evidence that mutations in splicing factors drive myeloid malignancy development, and identify spliceosomal changes as a mediator of IDH2-mutant leukaemogenesis.
Asunto(s)
Empalme Alternativo/genética , Carcinogénesis/genética , Epigénesis Genética , Leucemia Mieloide Aguda/genética , Animales , Línea Celular Tumoral , Proliferación Celular , Metilación de ADN , Proteínas de Unión al ADN/genética , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Isocitrato Deshidrogenasa/genética , Masculino , Mutación/genética , ARN Polimerasa II/metabolismo , Factores de Empalme Serina-Arginina/genética , TranscriptomaRESUMEN
Although Ras/mitogen-activated protein kinase (MAPK) signaling is activated in most human cancers, attempts to target this pathway using kinase-active site inhibitors have not typically led to durable clinical benefit. To address this shortcoming, we sought to test the feasibility of an alternative targeting strategy, focused on the ERK2 substrate binding domains, D and DEF binding pocket (DBP). Disabling the ERK2-DBP domain in mice caused baseline erythrocytosis. Consequently, we investigated the role of the ERK2-D and -DBP domains in disease, using a JAK2-dependent model of polycythemia vera (PV). Of note, inactivation of the ERK2-DBP domain promoted the progression of disease from PV to myelofibrosis, suggesting that the ERK2-DBP domain normally opposes progression. ERK2-DBP inactivation also prevented oncogenic JAK2 kinase (JAK2V617F) from promoting oncogene-induced senescence in vitro. The ERK2-DBP mutation attenuated JAK2-mediated oncogene-induced senescence by preventing the physical interaction of ERK2 with the transcription factor Egr1. Because inactivation of the ERK2-DBP created a functional ERK2 kinase limited to binding substrates through its D domain, these data suggested that the D domain substrates were responsible for promoting oncogene-induced progenitor growth and tumor progression and that pharmacologic targeting of the ERK2-D domain may attenuate cancer cell growth. Indeed, pharmacologic agents targeting the ERK2-D domain were effective in attenuating the growth of JAK2-dependent myeloproliferative neoplasm cell lines. Taken together, these data indicate that the ERK-D and -DBP domains can play distinct roles in the progression of neoplasms and that the D domain has the potential to be a potent therapeutic target in Ras/MAPK-dependent cancers.
Asunto(s)
Janus Quinasa 2 , Policitemia Vera , Animales , Línea Celular , Humanos , Janus Quinasa 2/genética , Sistema de Señalización de MAP Quinasas , Ratones , Proteínas Quinasas Activadas por Mitógenos , Fosforilación , Transducción de SeñalRESUMEN
The 2010 and 2017 editions of the European LeukemiaNet (ELN) recommendations for diagnosis and management of acute myeloid leukemia (AML) in adults are widely recognized among physicians and investigators. There have been major advances in our understanding of AML, including new knowledge about the molecular pathogenesis of AML, leading to an update of the disease classification, technological progress in genomic diagnostics and assessment of measurable residual disease, and the successful development of new therapeutic agents, such as FLT3, IDH1, IDH2, and BCL2 inhibitors. These advances have prompted this update that includes a revised ELN genetic risk classification, revised response criteria, and treatment recommendations.
Asunto(s)
Antineoplásicos , Leucemia Mieloide Aguda , Adulto , Antineoplásicos/uso terapéutico , Humanos , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/terapia , Mutación , Neoplasia Residual/diagnóstico , Neoplasia Residual/tratamiento farmacológico , Nucleofosmina , Pronóstico , Proteínas Proto-Oncogénicas c-bcl-2/genéticaRESUMEN
Leukemic transformation (LT) of myeloproliferative neoplasm (MPN) has a dismal prognosis and is largely fatal. Mutational inactivation of TP53 is the most common somatic event in LT; however, the mechanisms by which TP53 mutations promote LT remain unresolved. Using an allelic series of mouse models of Jak2/Trp53 mutant MPN, we identify that only biallelic inactivation of Trp53 results in LT (to a pure erythroleukemia [PEL]). This PEL arises from the megakaryocyte-erythroid progenitor population. Importantly, the bone morphogenetic protein 2/SMAD pathway is aberrantly activated during LT and results in abnormal self-renewal of megakaryocyte-erythroid progenitors. Finally, we identify that Jak2/Trp53 mutant PEL is characterized by recurrent copy number alterations and DNA damage. Using a synthetic lethality strategy, by targeting active DNA repair pathways, we show that this PEL is highly sensitive to combination WEE1 and poly(ADP-ribose) polymerase inhibition. These observations yield new mechanistic insights into the process of p53 mutant LT and offer new, clinically translatable therapeutic approaches.
Asunto(s)
Trastornos Mieloproliferativos , Proteína p53 Supresora de Tumor , Animales , Proteína Morfogenética Ósea 2/genética , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismo , Células Progenitoras de Megacariocitos y Eritrocitos/metabolismo , Megacariocitos/metabolismo , Ratones , Mutación , Trastornos Mieloproliferativos/genética , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Cytogenetics has long represented a critical component in the clinical evaluation of hematologic malignancies. Chromosome banding studies provide a simultaneous snapshot of genome-wide copy number and structural variation, which have been shown to drive tumorigenesis, define diseases, and guide treatment. Technological innovations in sequencing have ushered in our present-day clinical genomics era. With recent publications highlighting novel sequencing technologies as alternatives to conventional cytogenetic approaches, we, an international consortium of laboratory geneticists, pathologists, and oncologists, describe herein the advantages and limitations of both conventional chromosome banding and novel sequencing technologies and share our considerations on crucial next steps to implement these novel technologies in the global clinical setting for a more accurate cytogenetic evaluation, which may provide improved diagnosis and treatment management. Considering the clinical, logistic, technical, and financial implications, we provide points to consider for the global evolution of cytogenetic testing.
Asunto(s)
Neoplasias Hematológicas , Aberraciones Cromosómicas , Análisis Citogenético , Citogenética , Neoplasias Hematológicas/diagnóstico , Neoplasias Hematológicas/genética , HumanosRESUMEN
Mutations in chromatin regulator ASXL1 are frequently identified in myeloid malignancies, in particular â¼40% of patients with chronic myelomonocytic leukemia (CMML). ASXL1 mutations are associated with poor prognosis in CMML and significantly co-occur with NRAS mutations. Here, we show that concurrent ASXL1 and NRAS mutations defined a population of CMML patients who had shorter leukemia-free survival than those with ASXL1 mutation only. Corroborating this human data, Asxl1-/- accelerated CMML progression and promoted CMML transformation to acute myeloid leukemia (AML) in NrasG12D/+ mice. NrasG12D/+;Asxl1-/- (NA) leukemia cells displayed hyperactivation of MEK/ERK signaling, increased global levels of H3K27ac, upregulation of Flt3. Moreover, we find that NA-AML cells overexpressed all the major inhibitory immune checkpoint ligands: programmed death-ligand 1 (PD-L1)/PD-L2, CD155, and CD80/CD86. Among them, overexpression of PD-L1 and CD86 correlated with upregulation of AP-1 transcription factors (TFs) in NA-AML cells. An AP-1 inhibitor or short hairpin RNAs against AP-1 TF Jun decreased PD-L1 and CD86 expression in NA-AML cells. Once NA-AML cells were transplanted into syngeneic recipients, NA-derived T cells were not detectable. Host-derived wild-type T cells overexpressed programmed cell death protein 1 (PD-1) and T-cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT) receptors, leading to a predominant exhausted T-cell phenotype. Combined inhibition of MEK and BET resulted in downregulation of Flt3 and AP-1 expression, partial restoration of the immune microenvironment, enhancement of CD8 T-cell cytotoxicity, and prolonged survival in NA-AML mice. Our study suggests that combined targeted therapy and immunotherapy may be beneficial for treating secondary AML with concurrent ASXL1 and NRAS mutations.