RESUMEN
Chronic myelomonocytic leukemia (CMML) is a rare and challenging type of myeloproliferative neoplasm. Poor prognosis and high mortality, associated predominantly with progression to secondary acute myeloid leukemia (sAML), is still an unsolved problem. Despite a growing body of knowledge about the molecular repertoire of this disease, at present, the prognostic significance of CMML-associated mutations is controversial. The absence of available CMML cell lines and the small number of patients with CMML make pre-clinical testing and clinical trials complicated. Currently, specific therapy for CMML has not been approved; most of the currently available therapeutic approaches are based on myelodysplastic syndrome (MDS) and other myeloproliferative neoplasm (MNP) studies. In this regard, the development of the robust CMML animal models is currently the focus of interest. This review describes important studies concerning animal models of CMML, examples of methodological approaches, and the obtained hematologic phenotypes.
Asunto(s)
Leucemia Mielomonocítica Crónica/etiología , Animales , Epigénesis Genética , Xenoinjertos , Humanos , Leucemia Experimental/etiología , Leucemia Experimental/genética , Leucemia Experimental/terapia , Leucemia Mielomonocítica Crónica/genética , Leucemia Mielomonocítica Crónica/terapia , Ratones , Mutación , Oncogenes , FenotipoAsunto(s)
Elementos de Facilitación Genéticos , Factor de Transcripción GATA2/fisiología , Regulación Neoplásica de la Expresión Génica , Células Madre Hematopoyéticas/citología , Leucemia Experimental/patología , Animales , Factor de Transcripción GATA2/genética , Células Madre Hematopoyéticas/metabolismo , Leucemia Experimental/genética , Leucemia Experimental/metabolismo , Ratones , Ratones NoqueadosRESUMEN
Epigenetic regulation is essential for the maintenance of the hematopoietic system, and its deregulation is implicated in hematopoietic disorders. In this study, UTX, a demethylase for lysine 27 on histone H3 (H3K27) and a component of COMPASS-like and SWI/SNF complexes, played an essential role in the hematopoietic system by globally regulating aging-associated genes. Utx-deficient (UtxΔ/Δ) mice exhibited myeloid skewing with dysplasia, extramedullary hematopoiesis, impaired hematopoietic reconstituting ability, and increased susceptibility to leukemia, which are the hallmarks of hematopoietic aging. RNA-sequencing (RNA-seq) analysis revealed that Utx deficiency converted the gene expression profiles of young hematopoietic stem-progenitor cells (HSPCs) to those of aged HSPCs. Utx expression in hematopoietic stem cells declined with age, and UtxΔ/Δ HSPCs exhibited increased expression of an aging-associated marker, accumulation of reactive oxygen species, and impaired repair of DNA double-strand breaks. Pathway and chromatin immunoprecipitation analyses coupled with RNA-seq data indicated that UTX contributed to hematopoietic homeostasis mainly by maintaining the expression of genes downregulated with aging via demethylase-dependent and -independent epigenetic programming. Of note, comparison of pathway changes in UtxΔ/Δ HSPCs, aged muscle stem cells, aged fibroblasts, and aged induced neurons showed substantial overlap, strongly suggesting common aging mechanisms among different tissue stem cells.
Asunto(s)
Envejecimiento/genética , Regulación de la Expresión Génica/genética , Hematopoyesis/genética , Sistema Hematopoyético/fisiología , Código de Histonas/genética , Histona Demetilasas/fisiología , Animales , Senescencia Celular/genética , Roturas del ADN de Doble Cadena , Reparación del ADN , Femenino , Predisposición Genética a la Enfermedad , Hematopoyesis Extramedular , Histona Demetilasas/deficiencia , Histona Demetilasas/genética , Reconstitución Inmune , Histona Demetilasas con Dominio de Jumonji/metabolismo , Leucemia Experimental/genética , Leucemia Experimental/virología , Masculino , Ratones , Ratones Noqueados , Virus de la Leucemia Murina de Moloney/fisiología , Células Mieloides/patología , Quimera por Radiación , Especies Reactivas de Oxígeno/metabolismo , Proteínas Recombinantes/metabolismo , Factores de Transcripción/metabolismo , Integración ViralRESUMEN
Mixed lineage leukemia (MLL) arises from several KMT2A-gene chromosomal translocations. Shb gene deficiency has been found to exhibit pleiotropic effects in different models of leukemia, and consequently, this study aimed to investigate MLL-AF9-induced leukemia in Shb deficiency. Bone marrow cells from wild type and Shb knockout (KO) mice were transduced with the MLL-AF9 gene. Shb KO MLL-AF9 cells proliferated at an increased rate, exhibited altered expression of certain cytokine genes (Kitl, Csf3, IL6, IL1b) and higher expression of cell cycle genes (Ccnd2, Ccne1). Mice receiving Shb KO MLL-AF9 cells showed longer latency without displaying any difference in rates of leukemic cell proliferation, indicating a dichotomy between the in vitro and in vivo phenotypes. The mice with Shb deficient MLL-AF9 cells had a lower content of leukemic bone marrow cells allowing elevated normal hematopoiesis, explaining the longer latency. Finally, Shb knockout GFP-positive bone marrow cells showed a higher percentage of cells expressing myeloid markers. The result suggests a role of Shb in the progression of leukemia and that the relevance of the Shb gene is context-dependent as inferred from the differences between the in vivo and in vitro responses. These findings help to obtain an increased understanding of human MLL-AF9 leukemia.
Asunto(s)
Proliferación Celular , Transformación Celular Neoplásica/patología , Regulación Leucémica de la Expresión Génica , Leucemia Experimental/patología , Proteína de la Leucemia Mieloide-Linfoide/genética , Proteínas de Fusión Oncogénica/genética , Proteínas Proto-Oncogénicas/fisiología , Animales , Apoptosis , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Humanos , Leucemia Experimental/genética , Leucemia Experimental/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Células Tumorales CultivadasRESUMEN
Inversion of chromosome 16 is a consistent finding in patients with acute myeloid leukemia subtype M4 with eosinophilia, which generates a CBFB-MYH11 fusion gene. It is generally considered that CBFß-SMMHC, the fusion protein encoded by CBFB-MYH11, is a dominant negative repressor of RUNX1. However, recent findings challenge the RUNX1-repression model for CBFß-SMMHC-mediated leukemogenesis. To definitively address the role of Runx1 in CBFB-MYH11-induced leukemia, we crossed conditional Runx1 knockout mice (Runx1f/f) with conditional Cbfb-MYH11 knockin mice (Cbfb+/56M). On Mx1-Cre activation in hematopoietic cells induced by poly (I:C) injection, all Mx1-CreCbfb+/56M mice developed leukemia in 5 months, whereas no leukemia developed in Runx1f/fMx1-CreCbfb+/56M mice, and this effect was cell autonomous. Importantly, the abnormal myeloid progenitors (AMPs), a leukemia-initiating cell population induced by Cbfb-MYH11 in the bone marrow, decreased and disappeared in Runx1f/fMx1-CreCbfb+/56M mice. RNA-seq analysis of AMP cells showed that genes associated with proliferation, differentiation blockage, and leukemia initiation were differentially expressed between Mx1-CreCbfb+/56M and Runx1f/fMx1-CreCbfb+/56M mice. In addition, with the chromatin immunocleavage sequencing assay, we observed a significant enrichment of RUNX1/CBFß-SMMHC target genes in Runx1f/fMx1-CreCbfb+/56M cells, especially among downregulated genes, suggesting that RUNX1 and CBFß-SMMHC mainly function together as activators of gene expression through direct target gene binding. These data indicate that Runx1 is indispensable for Cbfb-MYH11-induced leukemogenesis by working together with CBFß-SMMHC to regulate critical genes associated with the generation of a functional AMP population.
Asunto(s)
Transformación Celular Neoplásica/genética , Subunidad alfa 2 del Factor de Unión al Sitio Principal/fisiología , Regulación Leucémica de la Expresión Génica , Leucemia Experimental/genética , Células Mieloides/metabolismo , Proteínas de Neoplasias/fisiología , Células Madre Neoplásicas/metabolismo , Proteínas de Fusión Oncogénica/fisiología , Activación Transcripcional , Animales , Subunidad alfa 2 del Factor de Unión al Sitio Principal/deficiencia , Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Técnicas de Sustitución del Gen , Humanos , Leucemia Experimental/etiología , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Células Mieloides/citología , Células Madre Neoplásicas/citología , Proteínas de Fusión Oncogénica/genética , Poli I-C/farmacología , ARN Mensajero/biosíntesis , ARN Mensajero/genética , ARN Neoplásico/biosíntesis , ARN Neoplásico/genética , RNA-Seq , Análisis de la Célula IndividualRESUMEN
The majority of childhood leukemias are precursor B-cell acute lymphoblastic leukemias (pB-ALLs) caused by a combination of prenatal genetic predispositions and oncogenic events occurring after birth. Although genetic predispositions are frequent in children (>1% to 5%), fewer than 1% of genetically predisposed carriers will develop pB-ALL. Although infectious stimuli are believed to play a major role in leukemogenesis, the critical determinants are not well defined. Here, by using murine models of pB-ALL, we show that microbiome disturbances incurred by antibiotic treatment early in life were sufficient to induce leukemia in genetically predisposed mice, even in the absence of infectious stimuli and independent of T cells. By using V4 and full-length 16S ribosomal RNA sequencing of a series of fecal samples, we found that genetic predisposition to pB-ALL (Pax5 heterozygosity or ETV6-RUNX1 fusion) shaped a distinct gut microbiome. Machine learning accurately (96.8%) predicted genetic predisposition using 40 of 3983 amplicon sequence variants as proxies for bacterial species. Transplantation of either wild-type (WT) or Pax5+/- hematopoietic bone marrow cells into WT recipient mice revealed that the microbiome is shaped and determined in a donor genotype-specific manner. Gas chromatography-mass spectrometry (GC-MS) analyses of sera from WT and Pax5+/- mice demonstrated the presence of a genotype-specific distinct metabolomic profile. Taken together, our data indicate that it is a lack of commensal microbiota rather than the presence of specific bacteria that promotes leukemia in genetically predisposed mice. Future large-scale longitudinal studies are required to determine whether targeted microbiome modification in children predisposed to pB-ALL could become a successful prevention strategy.
Asunto(s)
Susceptibilidad a Enfermedades , Disbiosis/complicaciones , Heces/microbiología , Microbioma Gastrointestinal , Leucemia Experimental/prevención & control , Factor de Transcripción PAX5/fisiología , Leucemia-Linfoma Linfoblástico de Células Precursoras B/prevención & control , Animales , Femenino , Leucemia Experimental/genética , Leucemia Experimental/microbiología , Leucemia Experimental/patología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/microbiología , Leucemia-Linfoma Linfoblástico de Células Precursoras B/patologíaRESUMEN
Apolipoprotein B editing enzyme, catalytic polypeptide 3 (APOBEC3) family members are cytidine deaminases that play important roles in intrinsic responses to retrovirus infection. Complex retroviruses like human immunodeficiency virus type 1 (HIV-1) encode the viral infectivity factor (Vif) protein to counteract APOBEC3 proteins. Vif induces degradation of APOBEC3G and other APOBEC3 proteins and thereby prevents their packaging into virions. It is not known if murine leukemia virus (MLV) encodes a Vif-like protein. Here, we show that the MLV P50 protein, produced from an alternatively spliced gag RNA, interacts with the C terminus of mouse APOBEC3 and prevents its packaging without causing its degradation. By infecting APOBEC3 knockout (KO) and wild-type (WT) mice with Friend or Moloney MLV P50-deficient viruses, we found that APOBEC3 restricts the mutant viruses more than WT viruses in vivo Replication of P50-mutant viruses in an APOBEC3-expressing stable cell line was also much slower than that of WT viruses, and overexpressing P50 in this cell line enhanced mutant virus replication. Thus, MLV encodes a protein, P50, that overcomes APOBEC3 restriction by preventing its packaging into virions.IMPORTANCE MLV has existed in mice for at least a million years, in spite of the existence of host restriction factors that block infection. Although MLV is considered a simple retrovirus compared to lentiviruses, it does encode proteins generated from alternatively spliced RNAs. Here, we show that P50, generated from an alternatively spliced RNA encoded in gag, counteracts APOBEC3 by blocking its packaging. MLV also encodes a protein, glycoGag, that increases capsid stability and limits APOBEC3 access to the reverse transcription complex (RTC). Thus, MLV has evolved multiple means of preventing APOBEC3 from blocking infection, explaining its survival as an infectious pathogen in mice.
Asunto(s)
Citidina Desaminasa/genética , Regulación Viral de la Expresión Génica , Productos del Gen gag/genética , Leucemia Experimental/genética , Virus de la Leucemia Murina de Moloney/genética , Infecciones por Retroviridae/genética , Infecciones Tumorales por Virus/genética , Empalme Alternativo , Animales , Cápside/metabolismo , Citidina Desaminasa/deficiencia , Productos del Gen gag/metabolismo , Células HEK293 , Interacciones Huésped-Patógeno/genética , Humanos , Leucemia Experimental/metabolismo , Leucemia Experimental/virología , Ratones , Ratones Noqueados , Virus de la Leucemia Murina de Moloney/metabolismo , Virus de la Leucemia Murina de Moloney/patogenicidad , Células 3T3 NIH , Infecciones por Retroviridae/metabolismo , Infecciones por Retroviridae/virología , Transducción de Señal , Infecciones Tumorales por Virus/metabolismo , Infecciones Tumorales por Virus/virología , Virión/genética , Virión/metabolismo , Virión/patogenicidad , Replicación ViralRESUMEN
Primary and acquired drug resistance imposes a major threat to achieving optimized clinical outcomes during cancer treatment. Aberrant changes in epigenetic modifications are closely involved in drug resistance of tumor cells. Using BET inhibitor (BETi) resistant leukemia cells as a model system, we demonstrated herein that genome-wide enhancer remodeling played a pivotal role in driving therapeutic resistance via compensational re-expression of pro-survival genes. Capitalizing on the CRISPR interference technology, we identified the second intron of IncRNA, PVT1, as a unique bona fide gained enhancer that restored MYC transcription independent of BRD4 recruitment in leukemia. A combined BETi and CDK7 inhibitor treatment abolished MYC transcription by impeding RNAPII loading without affecting PVT1-mediated chromatin looping at the MYC locus in BETi-resistant leukemia cells. Together, our findings have established the feasibility of targeting enhancer plasticity to overcome drug resistance associated with epigenetic therapies.
Asunto(s)
Leucemia Experimental/tratamiento farmacológico , Leucemia Experimental/genética , Proteínas Nucleares/antagonistas & inhibidores , Factores de Transcripción/antagonistas & inhibidores , Animales , Proteínas de Ciclo Celular/antagonistas & inhibidores , Línea Celular Tumoral , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Resistencia a Antineoplásicos/genética , Sinergismo Farmacológico , Elementos de Facilitación Genéticos , Femenino , Genes myc/efectos de los fármacos , Compuestos Heterocíclicos de 4 o más Anillos/administración & dosificación , Humanos , Células Jurkat , Células K562 , Leucemia Experimental/metabolismo , Ratones , Modelos Genéticos , Fenilendiaminas/administración & dosificación , Pirimidinas/administración & dosificación , ARN Polimerasa II/metabolismo , ARN Largo no Codificante/genética , Quinasa Activadora de Quinasas Ciclina-DependientesRESUMEN
The initiating mutations that contribute to cancer development are sometimes present in premalignant cells. Whether therapies targeting these mutations can eradicate premalignant cells is unclear. Acute myeloid leukemia (AML) is an attractive system for investigating the effect of preventative treatment because this disease is often preceded by a premalignant state (clonal hematopoiesis or myelodysplastic syndrome). In Npm1c/Dnmt3a mutant knock-in mice, a model of AML development, leukemia is preceded by a period of extended myeloid progenitor cell proliferation and self-renewal. We found that this self-renewal can be reversed by oral administration of a small molecule (VTP-50469) that targets the MLL1-Menin chromatin complex. These preclinical results support the hypothesis that individuals at high risk of developing AML might benefit from targeted epigenetic therapy in a preventative setting.
Asunto(s)
Terapia Genética/métodos , Leucemia Experimental/prevención & control , Leucemia Mieloide Aguda/prevención & control , Proteínas Nucleares/genética , Preleucemia/terapia , Animales , Cromatina/metabolismo , ADN (Citosina-5-)-Metiltransferasas/genética , ADN Metiltransferasa 3A , Técnicas de Sustitución del Gen , N-Metiltransferasa de Histona-Lisina/metabolismo , Leucemia Experimental/genética , Leucemia Mieloide Aguda/genética , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes , Mutación , Células Progenitoras Mieloides/patología , Proteína de la Leucemia Mieloide-Linfoide/metabolismo , Nucleofosmina , Preleucemia/genética , Preleucemia/patología , Proteínas Proto-Oncogénicas/metabolismoRESUMEN
Therapy-related and more specifically radiotherapy-associated acute myeloid leukaemia (AML) is a well-recognized potential complication of cytotoxic therapy for the treatment of a primary cancer. The CBA mouse model is used to study radiation leukaemogenesis mechanisms with Sfpi1/PU.1 deletion and point mutation already identified as driving events during AML development. To identify new pathways, we analysed 123 mouse radiation-induced AML (rAML) samples for the presence of mutations identified previously in human AML and found three genes to be mutated; Sfpi1 R235 (68%), Flt3-ITD (4%) and Kras G12 (3%), of which G12R was previously unreported. Importantly, a significant decrease in Sfpi1 gene expression is found almost exclusively in rAML samples without an Sfpi1 R235 mutation and is specifically associated with up-regulation of mir-1983 and mir-582-5p. Moreover, this down-regulation of Sfpi1 mRNA is negatively correlated with DNA methylation levels at specific CpG sites upstream of the Sfpi1 transcriptional start site. The down regulation of Sfpi1/PU.1 has also been reported in human AML cases revealing one common pathway of myeloid disruption between mouse and human AML where dysregulation of Sfpi1/PU.1 is a necessary step in AML development.
Asunto(s)
Regulación Leucémica de la Expresión Génica , Leucemia Experimental/genética , Leucemia Mieloide Aguda/genética , Leucemia Inducida por Radiación/genética , Proteínas Proto-Oncogénicas p21(ras)/genética , Proteínas Proto-Oncogénicas/genética , Transactivadores/genética , Animales , Carcinogénesis , Metilación de ADN/genética , Regulación hacia Abajo , Humanos , Ratones , Ratones Endogámicos CBA , MicroARNs/genética , Mutación , Regiones Promotoras Genéticas , Tirosina Quinasa 3 Similar a fmsRESUMEN
A better understanding of the development and progression of acute myelogenous leukemia (AML) is necessary to improve patient outcome. Here we define roles for the transcription factor Oct1/Pou2f1 in AML and normal hematopoiesis. Inappropriate reactivation of the CDX2 gene is widely observed in leukemia patients and in leukemia mouse models. We show that Oct1 associates with the CDX2 promoter in both normal and AML primary patient samples, but recruits the histone demethylase Jmjd1a/Kdm3a to remove the repressive H3K9me2 mark only in malignant specimens. The CpG DNA immediately adjacent to the Oct1 binding site within the CDX2 promoter exhibits variable DNA methylation in healthy control blood and bone marrow samples, but complete demethylation in AML samples. In MLL-AF9-driven mouse models, partial loss of Oct1 protects from myeloid leukemia. Complete Oct1 loss completely suppresses leukemia but results in lethality from bone marrow failure. Loss of Oct1 in normal hematopoietic transplants results in superficially normal long-term reconstitution; however, animals become acutely sensitive to 5-fluorouracil, indicating that Oct1 is dispensable for normal hematopoiesis but protects blood progenitor cells against external chemotoxic stress. These findings elucidate a novel and important role for Oct1 in AML.
Asunto(s)
Leucemia Mieloide Aguda/genética , Proteínas de Neoplasias/fisiología , Factor 1 de Transcripción de Unión a Octámeros/fisiología , Animales , Médula Ósea/patología , Trastornos de Fallo de la Médula Ósea/etiología , Trastornos de Fallo de la Médula Ósea/genética , Factor de Transcripción CDX2/biosíntesis , Factor de Transcripción CDX2/genética , Transformación Celular Neoplásica/genética , Islas de CpG , Metilación de ADN , Progresión de la Enfermedad , Fluorouracilo/toxicidad , Regulación Leucémica de la Expresión Génica , Células Madre Hematopoyéticas/efectos de los fármacos , Humanos , Histona Demetilasas con Dominio de Jumonji/metabolismo , Leucemia Experimental/genética , Leucemia Experimental/prevención & control , Leucemia Mieloide Aguda/metabolismo , Complejo Desacetilasa y Remodelación del Nucleosoma Mi-2/metabolismo , Ratones Endogámicos C57BL , Factor 1 de Transcripción de Unión a Octámeros/deficiencia , Proteínas de Fusión Oncogénica/fisiología , Regiones Promotoras Genéticas , Quimera por RadiaciónRESUMEN
Exposure to extremely low-frequency magnetic fields (ELF-MFs) has been classified by the International Agency for Research on Cancer (IARC) as "possibly carcinogenic to humans," based on limited scientific evidence concerning childhood leukemia. This assessment emphasized the lack of appropriate animal models recapitulating the natural history of this disease. Childhood B-cell acute lymphoblastic leukemia (B-ALL) is the result of complex interactions between genetic susceptibility and exposure to exogenous agents. The most common chromosomal alteration is the ETV6-RUNX1 fusion gene, which confers a low risk of developing the malignancy by originating a preleukemic clone requiring secondary hits for full-blown disease to appear. To develop potential prophylactic interventions, we need to identify the environmental triggers of the second hit. Recently, we generated a B-ALL mouse model of the human ETV6-RUNX1+ preleukemic state. Here, we present the results from the ARIMMORA pilot study, obtained by exposing 34 Sca1-ETV6-RUNX1 mice (vs. 27 unexposed) to a 50 Hz magnetic field of 1.5 mT with both fundamental and harmonic content, with an on/off cycle of 10 min/5 min, for 20 h/day, from conception until 3 months of age. Mice were monitored until 2 years of age and peripheral blood was periodically analyzed by flow cytometry. One of the exposed mice developed B-ALL while none of the non-exposed did. Although the results are statistically non-significant due to the limited number of mice used in this pilot experiment, overall, the results show that the newly developed Sca1-ETV6-RUNX1 mouse can be successfully used for ELF-MF exposure studies about the etiology of childhood B-ALL. Bioelectromagnetics. 2019;40:343-353. © 2019 Bioelectromagnetics Society.
Asunto(s)
Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Modelos Animales de Enfermedad , Campos Electromagnéticos/efectos adversos , Leucemia Experimental , Leucemia-Linfoma Linfoblástico de Células Precursoras , Proteínas Proto-Oncogénicas c-ets/genética , Ondas de Radio/efectos adversos , Proteínas Represoras/genética , Animales , Subunidad alfa 2 del Factor de Unión al Sitio Principal/metabolismo , Femenino , Humanos , Leucemia Experimental/genética , Leucemia Experimental/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Proyectos Piloto , Leucemia-Linfoma Linfoblástico de Células Precursoras/etiología , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Proteínas Proto-Oncogénicas c-ets/metabolismo , Proteínas Represoras/metabolismo , Proteína ETS de Variante de Translocación 6RESUMEN
Leukemogenic potential of MLL fusion with the coiled-coil domain-containing partner genes and the downstream target genes of this type of MLL fusion have not been clearly investigated. In this study, we demonstrated that the coiled-coil-four-helix bundle structure of EB1 that participated in the MLL/EB1 was required for immortalizing mouse bone marrow (BM) cells and producing myeloid, but not lymphoid, cell lines. Compared to MLL/AF10, MLL/EB1 had low leukemogenic ability. The MLL/EB1 cells grew more slowly owing to increased apoptosis in vitro and induced acute monocytic leukemia with an incomplete penetrance and longer survival in vivo. A comparative analysis of transcriptome profiling between MLL/EB1 and MLL/AF10 cell lines revealed that there was an at least two-fold difference in the induction of 318 genes; overall, 51.3% (163/318) of the genes were known to be bound by MLL, while 15.4% (49/318) were bound by both MLL and MLL/AF9. Analysis of the 318 genes using Gene Ontology-PANTHER overrepresentation test revealed significant differences in several biological processes, including cell differentiation, proliferation/programmed cell death, and cell homing/recruitment. The Ets1 gene, bound by MLL and MLL/AF9, was involved in several biological processes. We demonstrated that Ets1 was selectively upregulated by MLL/EB1. Short hairpin RNA knockdown of Ets1 in MLL/EB1 cells reduced the expression of CD115, apoptosis rate, competitive engraftment to BM and spleen, and incidence of leukemia and prolonged the survival of the diseased mice. Our results demonstrated that MLL/EB1 upregulated Ets1, which controlled the balance of leukemia cells between apoptosis and BM engraftment/clonal expansion. Novelty and impact of this study The leukemogenic potential of MLL fusion with cytoplasmic proteins containing coiled-coil dimerization domains and the downstream target genes of this type of MLL fusion remain largely unknown. Using a retroviral transduction/transplantation mouse model, we demonstrated that MLL fusion with the coiled-coil-four-helix bundle structure of EB1 has low leukemogenic ability; Ets1, which is upregulated by MLL/EB1, plays a critical role in leukemic transformation by balance between apoptosis and BM engraftment/clonal expansion.
Asunto(s)
Trasplante de Médula Ósea , Transformación Celular Neoplásica/patología , N-Metiltransferasa de Histona-Lisina/metabolismo , Leucemia Experimental/patología , Leucemia Monocítica Aguda/patología , Proteínas Asociadas a Microtúbulos/metabolismo , Proteína de la Leucemia Mieloide-Linfoide/metabolismo , Proteína Proto-Oncogénica c-ets-1/metabolismo , Animales , Apoptosis , Diferenciación Celular , Proliferación Celular , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Modelos Animales de Enfermedad , Perfilación de la Expresión Génica , Regulación Leucémica de la Expresión Génica , N-Metiltransferasa de Histona-Lisina/genética , Leucemia Experimental/genética , Leucemia Experimental/metabolismo , Leucemia Monocítica Aguda/genética , Leucemia Monocítica Aguda/metabolismo , Ratones , Ratones Endogámicos C57BL , Proteínas Asociadas a Microtúbulos/genética , Proteína de la Leucemia Mieloide-Linfoide/genética , Células 3T3 NIH , Proteínas de Fusión Oncogénica , Proteína Proto-Oncogénica c-ets-1/genéticaRESUMEN
Acute myeloid leukemia (AML), the most common acute leukemia in adults, increases exponentially with age. While a number of recent advances have improved treatment, high cure rates have not yet been achieved. Nucleophosmin (NPM1) is found mutated in nearly one-third of newly diagnosed cases and leads to NPM1 protein that is mislocalized to the cytoplasm instead of the nucleolus. If the mechanistic basis through which this mislocalization leads to malignancy could be revealed, this AML subtype may be targetable with new drugs. Here, we review the structure and functions of the normal and mutant forms of nucleophosmin. We discuss several recent studies that have shed light on the pathophysiology of NPM1 mutations. We discuss the importance of HOX gene misregulation in NPM1-mutated leukemias, as well as evidence for the reliance of mutated NPM1 on its continued nuclear export. Together, these aspects, as well as new tools to manipulate and study NPM1, open the door to new therapeutic strategies that may ultimately improve treatment of this common subtype of AML.
Asunto(s)
Leucemia Mieloide Aguda/genética , Proteínas de Neoplasias/genética , Proteínas Nucleares/genética , Animales , Nucléolo Celular/metabolismo , Transformación Celular Neoplásica/genética , Citoplasma/metabolismo , Mutación del Sistema de Lectura , Regulación Leucémica de la Expresión Génica , Genes Homeobox , Inestabilidad Genómica , Humanos , Leucemia Experimental/genética , Leucemia Mieloide Aguda/fisiopatología , Ratones , Ratones Transgénicos , Terapia Molecular Dirigida , Mutación Missense , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/química , Proteínas de Neoplasias/fisiología , Proteínas Nucleares/antagonistas & inhibidores , Proteínas Nucleares/química , Proteínas Nucleares/fisiología , Nucleofosmina , Dominios Proteicos , Isoformas de Proteínas/química , Isoformas de Proteínas/fisiología , Transporte de Proteínas , Relación Estructura-ActividadRESUMEN
An epigenetic modulator Additional sex combs-like 1 (ASXL1) is recurrently mutated in myeloid neoplasms such as myelodysplastic syndromes (MDS), acute myeloid leukemia (AML) and myeloproliferative neoplasms (MPNs). ASXL1 mutations are also frequently detected in clonal hematopoiesis with indeterminate potential (CHIP), which is the clonal expansion of premalignant hematopoietic cells without any evidence of hematological malignancies. Thus, understanding the roles of ASXL1 in hematopoiesis and myeloid neoplasms is a clinically crucial issue. ASXL1 mutations in hematological neoplasms are typically frameshift or nonsense mutations and occur near the 5' end of the last exon, thereby the transcripts would escape from nonsense-mediated decay, Indeed, we identified the C-terminally truncated mutant protein of ASXL1 in several cell lines derived from patients with myeloid leukemia. In mouse models, expression of the mutant ASXL1 results in impaired hematopoiesis and promotes development of myeloid neoplasms. In addition, recent findings from biochemical analysis have demonstrated that the mutant ASXL1 protein gains new functions including enhancing catalytic activity of BRCA1-associated protein 1 (BAP1), resulting in reduction of H2AK119ub and aberrant gene expression essential for myeloid transformation. In this review, we will focus on the pivotal roles of the mutant ASXL1 on histone modifications and myeloid transformation.
Asunto(s)
Código de Histonas , Leucemia Mieloide Aguda/genética , Síndromes Mielodisplásicos/genética , Trastornos Mieloproliferativos/genética , Proteínas de Neoplasias/genética , Proteínas Represoras/genética , Animales , Transformación Celular Neoplásica/genética , Codón sin Sentido , Mutación del Sistema de Lectura , Mutación con Ganancia de Función , Regulación Leucémica de la Expresión Génica , Hematopoyesis/genética , Proteínas de Homeodominio/metabolismo , Humanos , Leucemia Experimental/genética , Leucemia Experimental/fisiopatología , Ratones , Terapia Molecular Dirigida , Complejos Multiproteicos/fisiología , Proteínas de Neoplasias/fisiología , Procesamiento Proteico-Postraduccional , Proteínas Represoras/deficiencia , Proteínas Represoras/fisiología , Relación Estructura-Actividad , Proteínas Supresoras de Tumor/fisiología , Ubiquitina Tiolesterasa/fisiología , UbiquitinaciónRESUMEN
Leukemias exhibit a dysregulated developmental program mediated through both genetic and epigenetic mechanisms. Although IKZF2 is expressed in hematopoietic stem cells (HSCs), we found that it is dispensable for mouse and human HSC function. In contrast to its role as a tumor suppressor in hypodiploid B-acute lymphoblastic leukemia, we found that IKZF2 is required for myeloid leukemia. IKZF2 is highly expressed in leukemic stem cells (LSCs), and its deficiency results in defective LSC function. IKZF2 depletion in acute myeloid leukemia (AML) cells reduced colony formation, increased differentiation and apoptosis, and delayed leukemogenesis. Gene expression, chromatin accessibility, and direct IKZF2 binding in MLL-AF9 LSCs demonstrate that IKZF2 regulates a HOXA9 self-renewal gene expression program and inhibits a C/EBP-driven differentiation program. Ectopic HOXA9 expression and CEBPE depletion rescued the effects of IKZF2 depletion. Thus, our study shows that IKZF2 regulates the AML LSC program and provides a rationale to therapeutically target IKZF2 in myeloid leukemia.
Asunto(s)
Diferenciación Celular , Autorrenovación de las Células , Proteínas de Unión al ADN/fisiología , Regulación Leucémica de la Expresión Génica , Leucemia Experimental/patología , Leucemia Mieloide Aguda/patología , Células Madre Neoplásicas/patología , Factores de Transcripción/fisiología , Animales , Cromatina/genética , Cromatina/metabolismo , Femenino , Hematopoyesis , Leucemia Experimental/genética , Leucemia Experimental/metabolismo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Células Madre Neoplásicas/metabolismoRESUMEN
Autophagy maintains hematopoietic stem cell integrity and prevents malignant transformation. In addition to bulk degradation, selective autophagy serves as an intracellular quality control mechanism and requires autophagy receptors, such as p62 (SQSTM1), to specifically bridge the ubiquitinated cargos into autophagosomes. Here, we investigated the function of p62 in acute myeloid leukemia (AML) in vitro and in murine in vivo models of AML. Loss of p62 impaired expansion and colony-forming ability of leukemia cells and prolonged latency of leukemia development in mice. High p62 expression was associated with poor prognosis in human AML. Using quantitative mass spectrometry, we identified enrichment of mitochondrial proteins upon immunoprecipitation of p62. Loss of p62 significantly delayed removal of dysfunctional mitochondria, increased mitochondrial superoxide levels, and impaired mitochondrial respiration. Moreover, we demonstrated that the autophagy-dependent function of p62 is essential for cell growth and effective mitochondrial degradation by mitophagy. Our results highlight the prominent role of selective autophagy in leukemia progression, and specifically, the importance of mitophagy to maintain mitochondrial integrity.
Asunto(s)
Autofagia , Leucemia Experimental/patología , Leucemia Mieloide Aguda/patología , Mitofagia , Proteína Sequestosoma-1/metabolismo , Proteína Sequestosoma-1/fisiología , Animales , Estudios de Seguimiento , Humanos , Leucemia Experimental/genética , Leucemia Experimental/metabolismo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Ratones , Ratones Noqueados , Pronóstico , Tasa de Supervivencia , Células Tumorales CultivadasRESUMEN
Transformation of hematopoietic stem cells by the BCR-FGFR1 fusion kinase found in a variant of stem cell leukemia/lymphoma (SCLL) syndrome leads to development of B-lymphomas in syngeneic mice and humans. In this study, we show that the relatively rapid onset of this leukemia is potentially related to oncogenic domains within the BCR component. BCR recruited a guanidine nucleotide exchange factor (GEF) domain to the fusion kinase to facilitate activation of small GTPases such as the Ras homology gene family, member A (RHOA). Deletion of this GEF domain increased leukemogenesis, enhanced cell survival and proliferation, and promoted stem cell expansion and lymph node metastasis. This suggests that, in an SCLL context, the presence of the endogenous GEF motif leads to reduced leukemogenesis. Indeed, loss of the GEF domain suppressed activation of RHOA and PTEN, leading to increased activation of AKT. Loss of the GEF domain enhanced cell proliferation and invasion potential, which was also observed in cells in which RHOA is knocked down, supported by the observation that overexpression of RHOA leads to reduced viability and invasion. In vivo depletion of RHOA in SCLL cells significantly increased disease progression and shortened latency. Collectively, these data show that the BCR GEF domain affects phenotypes associated with progression of SCLL through suppression of RHOA signaling. SIGNIFICANCE: RHOA activation is a critical event in the progression of BCR-FGFR1-driven leukemogenesis in stem cell leukemia and lymphoma syndrome and is regulated by the BCR GEF domain.
Asunto(s)
Factores de Intercambio de Guanina Nucleótido/metabolismo , Leucemia Experimental/patología , Linfoma/patología , Células Precursoras de Linfocitos B/patología , Proteínas Proto-Oncogénicas c-bcr/metabolismo , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos/metabolismo , Proteínas de Unión al GTP rho/metabolismo , Animales , Movimiento Celular , Proliferación Celular , Células Cultivadas , Factores de Intercambio de Guanina Nucleótido/genética , Leucemia Experimental/genética , Leucemia Experimental/metabolismo , Linfoma/genética , Linfoma/metabolismo , Ratones , Ratones Endogámicos BALB C , Células Precursoras de Linfocitos B/metabolismo , Dominios Proteicos , Proteínas Proto-Oncogénicas c-bcr/genética , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos/genética , Transducción de Señal , Proteínas de Unión al GTP rho/genética , Proteína de Unión al GTP rhoARESUMEN
The transcription factor RUNX1 is required in the embryo for formation of the adult hematopoietic system. Here, we describe the seminal findings that led to the discovery of RUNX1 and of its critical role in blood cell formation in the embryo from hemogenic endothelium (HE). We also present RNA-sequencing data demonstrating that HE cells in different anatomic sites, which produce hematopoietic progenitors with dissimilar differentiation potentials, are molecularly distinct. Hemogenic and non-HE cells in the yolk sac are more closely related to each other than either is to hemogenic or non-HE cells in the major arteries. Therefore, a major driver of the different lineage potentials of the committed erythro-myeloid progenitors that emerge in the yolk sac versus hematopoietic stem cells that originate in the major arteries is likely to be the distinct molecular properties of the HE cells from which they are derived. We used bioinformatics analyses to predict signaling pathways active in arterial HE, which include the functionally validated pathways Notch, Wnt, and Hedgehog. We also used a novel bioinformatics approach to assemble transcriptional regulatory networks and predict transcription factors that may be specifically involved in hematopoietic cell formation from arterial HE, which is the origin of the adult hematopoietic system.
Asunto(s)
Subunidad alfa 2 del Factor de Unión al Sitio Principal/fisiología , Hemangioblastos/fisiología , Hematopoyesis/fisiología , Animales , Arterias/citología , Arterias/embriología , Subunidad alfa 2 del Factor de Unión al Sitio Principal/deficiencia , Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Subunidad beta del Factor de Unión al Sitio Principal/deficiencia , Subunidad beta del Factor de Unión al Sitio Principal/genética , Subunidad beta del Factor de Unión al Sitio Principal/fisiología , Proteínas de Drosophila/genética , Sangre Fetal/fisiología , Regulación del Desarrollo de la Expresión Génica , Humanos , Leucemia Experimental/genética , Leucemia Experimental/virología , Leucemia Mieloide Aguda/genética , Ratones , Ratones Noqueados , Proteínas de Fusión Oncogénica/genética , Proteínas de Fusión Oncogénica/fisiología , Transcripción Genética , Saco Vitelino/citologíaRESUMEN
RUNX1 is frequently mutated in T-cell acute lymphoblastic leukemia (T-ALL). The spectrum of RUNX1 mutations has led to the notion that it acts as a tumor suppressor in this context; however, other studies have placed RUNX1, along with transcription factors TAL1 and NOTCH1, as core drivers of an oncogenic transcriptional program. To reconcile these divergent roles, we knocked down RUNX1 in human T-ALL cell lines and deleted Runx1 or Cbfb in primary mouse T-cell leukemias. RUNX1 depletion consistently resulted in reduced cell proliferation and increased apoptosis. RUNX1 upregulated variable sets of target genes in each cell line, but consistently included a core set of oncogenic effectors including insulin-like growth factor 1 receptor (IGF1R) and NRAS. Our results support the conclusion that RUNX1 has a net positive effect on cell growth in the context of established T-ALL.