RESUMEN
The diversity of regulatory T (Treg) cells in health and in disease remains unclear. Individuals with colorectal cancer harbor a subpopulation of RORγt+ Treg cells with elevated expression of ß-catenin and pro-inflammatory properties. Here we show progressive expansion of RORγt+ Treg cells in individuals with inflammatory bowel disease during inflammation and early dysplasia. Activating Wnt-ß-catenin signaling in human and murine Treg cells was sufficient to recapitulate the disease-associated increase in the frequency of RORγt+ Treg cells coexpressing multiple pro-inflammatory cytokines. Binding of the ß-catenin interacting partner, TCF-1, to DNA overlapped with Foxp3 binding at enhancer sites of pro-inflammatory pathway genes. Sustained Wnt-ß-catenin activation induced newly accessible chromatin sites in these genes and upregulated their expression. These findings indicate that TCF-1 and Foxp3 together limit the expression of pro-inflammatory genes in Treg cells. Activation of ß-catenin signaling interferes with this function and promotes the disease-associated RORγt+ Treg phenotype.
Asunto(s)
Proliferación Celular , Reprogramación Celular , Colitis Ulcerosa/metabolismo , Neoplasias Asociadas a Colitis/metabolismo , Enfermedad de Crohn/metabolismo , Epigénesis Genética , Activación de Linfocitos , Linfocitos T Reguladores/metabolismo , Vía de Señalización Wnt , Animales , Estudios de Casos y Controles , Células Cultivadas , Colitis Ulcerosa/genética , Colitis Ulcerosa/inmunología , Neoplasias Asociadas a Colitis/genética , Neoplasias Asociadas a Colitis/inmunología , Enfermedad de Crohn/genética , Enfermedad de Crohn/inmunología , Citocinas/genética , Citocinas/metabolismo , Modelos Animales de Enfermedad , Factores de Transcripción Forkhead/genética , Factores de Transcripción Forkhead/metabolismo , Regulación Neoplásica de la Expresión Génica , Factor Nuclear 1-alfa del Hepatocito/genética , Factor Nuclear 1-alfa del Hepatocito/metabolismo , Humanos , Ratones Endogámicos C57BL , Ratones Transgénicos , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/genética , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismo , Fenotipo , Factor 1 de Transcripción de Linfocitos T , Linfocitos T Reguladores/inmunologíaRESUMEN
Thymocyte development requires a complex orchestration of multiple transcription factors. Ablating either TCF-1 or HEB in CD4+CD8+ thymocytes elicits similar developmental outcomes including increased proliferation, decreased survival, and fewer late Tcra rearrangements. Here, we provide a mechanistic explanation for these similarities by showing that TCF-1 and HEB share ~7,000 DNA-binding sites genome wide and promote chromatin accessibility. The binding of both TCF-1 and HEB was required at these shared sites for epigenetic and transcriptional gene regulation. Binding of TCF-1 and HEB to their conserved motifs in the enhancer regions of genes associated with T cell differentiation promoted their expression. Binding to sites lacking conserved motifs in the promoter regions of cell-cycle-associated genes limited proliferation. TCF-1 displaced nucleosomes, allowing for chromatin accessibility. Importantly, TCF-1 inhibited Notch signaling and consequently protected HEB from Notch-mediated proteasomal degradation. Thus, TCF-1 shifts nucleosomes and safeguards HEB, thereby enabling their cooperation in establishing the epigenetic and transcription profiles of CD4+CD8+ thymocytes.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/inmunología , Regulación de la Expresión Génica/inmunología , Factor Nuclear 1-alfa del Hepatocito/inmunología , Linfopoyesis/inmunología , Timocitos/inmunología , Animales , Antígenos CD4/inmunología , Antígenos CD8/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones TransgénicosRESUMEN
Activation of ß-catenin in CD4+CD8+ double-positive (DP) thymocytes halts development before the thymic selection stage and predisposes to transformation. Leukemogenesis, but not the developmental block, depends on TCF-1, ß-catenin's DNA-binding partner. In this study, we show that ß-catenin activation directs the DNA-binding protein HEB to block DP thymocyte development. Conditional loss of HEB in DP thymocytes with stabilized ß-catenin restores the frequencies of postselection TCRßhi/CCR7+ and TCRßhi/CD69+ DPs and their cell-cycle profile. This recovery is associated with significant reversal of ß-catenin-induced expression changes, particularly those related to the CD69+ DP cell signature and to cell-cycle pathways. Stabilizing ß-catenin in DP thymocytes directs HEB binding to ≈11,000 novel DNA sites throughout the genome. Novel HEB sites mark most CD69+ DP cell signature genes that change expression upon activation of ß-catenin and then revert after loss of HEB. Moreover, many of the novel HEB sites occupy promoter regions of genes enriched in mitotic cell cycle pathways. HEB binding to those regions correlates with downregulation of the associated genes, and HEB inactivation restores expression to physiologic levels. These findings highlight a molecular interplay between HEB and ß-catenin that can impair thymic development.
Asunto(s)
Timocitos , Timo , beta Catenina , Animales , beta Catenina/metabolismo , beta Catenina/genética , Ratones , Timocitos/metabolismo , Timocitos/inmunología , Timo/inmunología , Timo/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Diferenciación Celular/inmunología , Diferenciación Celular/genética , Estabilidad Proteica , Antígenos de Diferenciación de Linfocitos T/genética , Antígenos de Diferenciación de Linfocitos T/metabolismo , Lectinas Tipo C/metabolismo , Lectinas Tipo C/genéticaRESUMEN
Understanding the mechanisms promoting chromosomal translocations of the rearranging receptor loci in leukemia and lymphoma remains incomplete. Here we show that leukemias induced by aberrant activation of ß-catenin in thymocytes, which bear recurrent Tcra/Myc-Pvt1 translocations, depend on Tcf-1. The DNA double strand breaks (DSBs) in the Tcra site of the translocation are Rag-generated, whereas the Myc-Pvt1 DSBs are not. Aberrantly activated ß-catenin redirects Tcf-1 binding to novel DNA sites to alter chromatin accessibility and down-regulate genome-stability pathways. Impaired homologous recombination (HR) DNA repair and replication checkpoints lead to retention of DSBs that promote translocations and transformation of double-positive (DP) thymocytes. The resulting lymphomas, which resemble human T cell acute lymphoblastic leukemia (T-ALL), are sensitive to PARP inhibitors (PARPis). Our findings indicate that aberrant ß-catenin signaling contributes to translocations in thymocytes by guiding Tcf-1 to promote the generation and retention of replication-induced DSBs allowing their coexistence with Rag-generated DSBs. Thus, PARPis could offer therapeutic options in hematologic malignancies with active Wnt/ß-catenin signaling.
Asunto(s)
Transformación Celular Neoplásica , Inestabilidad Genómica , Factor Nuclear 1-alfa del Hepatocito , Leucemia-Linfoma Linfoblástico de Células T Precursoras , Timocitos , Translocación Genética , beta Catenina , Animales , Transformación Celular Neoplásica/genética , Roturas del ADN de Doble Cadena , Inestabilidad Genómica/genética , Factor Nuclear 1-alfa del Hepatocito/genética , Factor Nuclear 1-alfa del Hepatocito/metabolismo , Ratones , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patología , Proteínas Proto-Oncogénicas c-myc/genética , ARN Largo no Codificante/genética , Timocitos/patología , Translocación Genética/genética , beta Catenina/genética , beta Catenina/metabolismoRESUMEN
BRCA1 is critical for maintenance of genomic stability and interacts directly with several proteins that regulate hematopoietic stem cell function and are part of the Fanconi anemia (FA) double-strand break DNA repair pathway. The effects of complete BRCA1 deficiency on bone marrow (BM) function are unknown. To test the hypothesis that Brca1 is essential in hematopoiesis, we developed a conditional mouse model with Mx1-Cre-mediated Brca1 deletion. Mice lacking Brca1 in the BM have baseline cytopenias and develop spontaneous bone marrow failure or diverse hematologic malignancies by 6 months of age. Brca1(-/-) BM cells have a reduced capacity to form hematopoietic colonies in vitro and to reconstitute hematopoiesis in irradiated recipients, consistent with a hematopoietic progenitor functional defect. Brca1(-/-) BM cells also show FA-like hypersensitivity to the DNA crosslinking agent mitomycin C, and karyotypes feature genomic instability. Taken together, our results show that loss of Brca1 in murine BM causes hematopoietic defects similar to those seen in people with FA, which provides strong evidence that Brca1 is critical for normal hematopoiesis and that Brca1 is a bona fide FA-like gene.
Asunto(s)
Proteína BRCA1/deficiencia , Proteína BRCA1/genética , Neoplasias Hematológicas/genética , Hemoglobinuria Paroxística/genética , Anemia Aplásica , Animales , Médula Ósea/patología , Células de la Médula Ósea/metabolismo , Células de la Médula Ósea/patología , Enfermedades de la Médula Ósea , Trastornos de Fallo de la Médula Ósea , Modelos Animales de Enfermedad , Inestabilidad Genómica , Neoplasias Hematológicas/diagnóstico , Hematopoyesis/genética , Hemoglobinuria Paroxística/diagnóstico , Humanos , Infiltración Leucémica , Recuento de Leucocitos , Ratones , Ratones Noqueados , Pancitopenia/genética , Pancitopenia/patología , FenotipoRESUMEN
The faithful transmission of DNA methylation patterns through cell divisions is essential for the daughter cells to retain a proper cell identity. To achieve a comprehensive assessment of methylation fidelity, we implemented a genome-scale hairpin bisulfite sequencing approach to generate methylation data for DNA double strands simultaneously. We show here that methylation fidelity increases globally during differentiation of mouse embryonic stem cells (mESCs), and is particularly high in the promoter regions of actively expressed genes and positively correlated with active histone modification marks and binding of transcription factors. The majority of intermediately (40%-60%) methylated CpG dinucleotides are hemi-methylated and have low methylation fidelity, particularly in the differentiating mESCs. While 5-hmC and 5-mC tend to coexist, there is no significant correlation between 5-hmC levels and methylation fidelity. Our findings may shed new light on our understanding of the origins of methylation variations and the mechanisms underlying DNA methylation transmission.
Asunto(s)
Diferenciación Celular , Proliferación Celular , Metilación de ADN , Células Madre Embrionarias/fisiología , Animales , Células Cultivadas , Islas de CpG , Epigénesis Genética , Expresión Génica , Histonas/metabolismo , Ratones , Unión Proteica , Análisis de Secuencia de ADN , Factores de Transcripción/metabolismoRESUMEN
It is generally assumed that gain- and loss-of-function manipulations of a functionally important gene should lead to the opposite phenotypes. We show in this study that both overexpression and knockout of microRNA (miR)-126 surprisingly result in enhanced leukemogenesis in cooperation with the t(8;21) fusion genes AML1-ETO/RUNX1-RUNX1T1 and AML1-ETO9a (a potent oncogenic isoform of AML1-ETO). In accordance with our observation that increased expression of miR-126 is associated with unfavorable survival in patients with t(8;21) acute myeloid leukemia (AML), we show that miR-126 overexpression exhibits a stronger effect on long-term survival and progression of AML1-ETO9a-mediated leukemia stem cells/leukemia initiating cells (LSCs/LICs) in mice than does miR-126 knockout. Furthermore, miR-126 knockout substantially enhances responsiveness of leukemia cells to standard chemotherapy. Mechanistically, miR-126 overexpression activates genes that are highly expressed in LSCs/LICs and/or primitive hematopoietic stem/progenitor cells, likely through targeting ERRFI1 and SPRED1, whereas miR-126 knockout activates genes that are highly expressed in committed, more differentiated hematopoietic progenitor cells, presumably through inducing FZD7 expression. Our data demonstrate that miR-126 plays a critical but 2-faceted role in leukemia and thereby uncover a new layer of miRNA regulation in cancer. Moreover, because miR-126 depletion can sensitize AML cells to standard chemotherapy, our data also suggest that miR-126 represents a promising therapeutic target.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Transformación Celular Neoplásica/patología , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patología , MicroARNs/genética , Animales , Diferenciación Celular/genética , Cromosomas Humanos Par 21/genética , Cromosomas Humanos Par 8/genética , Femenino , Humanos , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/mortalidad , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Estadificación de Neoplasias , Proteínas de Fusión Oncogénica/genética , Pronóstico , Tasa de Supervivencia , Translocación Genética/genéticaRESUMEN
The ten-eleven translocation 1 (TET1) gene is the founding member of the TET family of enzymes (TET1/2/3) that convert 5-methylcytosine to 5-hydroxymethylcytosine. Although TET1 was first identified as a fusion partner of the mixed lineage leukemia (MLL) gene in acute myeloid leukemia carrying t(10,11), its definitive role in leukemia is unclear. In contrast to the frequent down-regulation (or loss-of-function mutations) and critical tumor-suppressor roles of the three TET genes observed in various types of cancers, here we show that TET1 is a direct target of MLL-fusion proteins and is significantly up-regulated in MLL-rearranged leukemia, leading to a global increase of 5-hydroxymethylcytosine level. Furthermore, our both in vitro and in vivo functional studies demonstrate that Tet1 plays an indispensable oncogenic role in the development of MLL-rearranged leukemia, through coordination with MLL-fusion proteins in regulating their critical cotargets, including homeobox A9 (Hoxa9)/myeloid ecotropic viral integration 1 (Meis1)/pre-B-cell leukemia homeobox 3 (Pbx3) genes. Collectively, our data delineate an MLL-fusion/Tet1/Hoxa9/Meis1/Pbx3 signaling axis in MLL-rearranged leukemia and highlight TET1 as a potential therapeutic target in treating this presently therapy-resistant disease.
Asunto(s)
Proteínas de Unión al ADN/metabolismo , Regulación Neoplásica de la Expresión Génica/fisiología , Leucemia Mieloide Aguda/metabolismo , Proteína de la Leucemia Mieloide-Linfoide/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Transducción de Señal/fisiología , 5-Metilcitosina/análogos & derivados , Inmunoprecipitación de Cromatina , Cromatografía Liquida , Citosina/análogos & derivados , Citosina/metabolismo , Perfilación de la Expresión Génica , N-Metiltransferasa de Histona-Lisina , Proteínas de Homeodominio/metabolismo , Humanos , Immunoblotting , Análisis por Micromatrices , Oxigenasas de Función Mixta , Proteína 1 del Sitio de Integración Viral Ecotrópica Mieloide , Proteínas de Neoplasias/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Transducción de Señal/genética , Espectrometría de Masas en TándemRESUMEN
MicroRNAs (miRNAs), small noncoding RNAs that regulate target gene mRNAs, are known to contribute to pathogenesis of cancers. Acute myeloid leukemia (AML) is a group of heterogeneous hematopoietic malignancies with various chromosomal and/or molecular abnormalities. AML with chromosomal translocations involving the mixed lineage leukemia (MLL) gene are usually associated with poor survival. In the present study, through a large-scale, genomewide miRNA expression assay, we show that microRNA-9 (miR-9) is the most specifically up-regulated miRNA in MLL-rearranged AML compared with both normal control and non-MLL-rearranged AML. We demonstrate that miR-9 is a direct target of MLL fusion proteins and can be significantly up-regulated in expression by the latter in human and mouse hematopoietic stem/progenitor cells. Depletion of endogenous miR-9 expression by an appropriate antagomiR can significantly inhibit cell growth/viability and promote apoptosis in human MLL-rearranged AML cells, and the opposite is true when expression of miR-9 is forced. Blocking endogenous miR-9 function by anti-miRNA sponge can significantly inhibit, whereas forced expression of miR-9 can significantly promote, MLL fusion-induced immortalization/transformation of normal mouse bone marrow progenitor cells in vitro. Furthermore, forced expression of miR-9 can significantly promote MLL fusion-mediated leukemogenesis in vivo. In addition, a group of putative target genes of miR-9 exhibited a significant inverse correlation of expression with miR-9 in a series of leukemia sample sets, suggesting that they are potential targets of miR-9 in MLL-rearranged AML. Collectively, our data demonstrate that miR-9 is a critical oncomiR in MLL-rearranged AML and can serve as a potential therapeutic target to treat this dismal disease.
Asunto(s)
Leucemia Mieloide Aguda/genética , MicroARNs/fisiología , Proteína de la Leucemia Mieloide-Linfoide/genética , Apoptosis/genética , Supervivencia Celular/genética , Proteínas de Unión al ADN/fisiología , Humanos , Leucemia Mieloide Aguda/patología , Proteína del Locus del Complejo MDS1 y EV11 , MicroARNs/genética , Proto-Oncogenes/fisiología , Factores de Transcripción/fisiologíaRESUMEN
Pontocerebellar hypoplasia (PCH) is characterized by hypoplasia and atrophy of the cerebellum, variable pontine atrophy, microcephaly, severe mental and motor impairments and seizures. Mutations in 11 genes have been reported in 8 out of 10 forms of PCH. Recessive mutations in the mitochondrial arginyl-transfer RNA synthetase gene (RARS2) have been recently associated with PCH type 6, which is characterized by early-onset encephalopathy with signs of oxidative phosphorylation defect. Here we describe the clinical presentation, neuroimaging findings and molecular characterizations of two siblings with a clinical diagnosis of PCH who displayed a novel variant (c.-2A>G) in the 5'-UTR of the RARS2 gene in the homozygous state. This variant was identified through next-generation sequencing testing of a panel of nine genes known to be involved in PCH. Gene expression and functional studies demonstrated that the c.-2A>G sequence change directly leads to a reduced RARS2 messenger RNA expression in the patients by decreasing RARS2 promoter activity, thus providing evidence that mutations in the RARS2 promoter are likely to represent a new causal mechanism of PCH6.
Asunto(s)
Arginino-ARNt Ligasa/genética , Regiones Promotoras Genéticas , Secuencia de Bases , Enfermedades Cerebelosas/diagnóstico , Enfermedades Cerebelosas/genética , Preescolar , Análisis Mutacional de ADN , Femenino , Estudios de Asociación Genética , Humanos , Lactante , Masculino , Datos de Secuencia Molecular , Mutación Missense , Mutación PuntualRESUMEN
Although PBX proteins are known to increase DNA-binding/transcriptional activity of HOX proteins through their direct binding, the functional importance of their interaction in leukemogenesis is unclear.We recently reported that overexpression of a 4-homeobox-gene signature (ie, PBX3/HOXA7/HOXA9/HOXA11) is an independent predictor of poor survival in patients with cytogenetically abnormal acute myeloid leukemia (CA-AML). Here we show that it is PBX3, but not PBX1 or PBX2, that is consistently coexpressed with HOXA9 in various subtypes of CA-AML, particularly MLL-rearranged AML, and thus appears as a potential pathologic cofactor of HOXA9 in CA-AML. We then show that depletion of endogenous Pbx3 expression by shRNA significantly inhibits MLL-fusion-mediated cell transformation, and coexpressed PBX3 exhibits a significantly synergistic effect with HOXA9 in promoting cell transformation in vitro and leukemogenesis in vivo. Furthermore, as a proof of concept, we show that a small peptide, namely HXR9, which was developed to specifically disrupt the interactions between HOX and PBX proteins, can selectively kill leukemic cells with overexpression of HOXA/PBX3 genes. Collectively, our data suggest that PBX3 is a critical cofactor of HOXA9 in leukemogenesis, and targeting their interaction is a feasible strategy to treat presently therapy resistant CA-AML (eg, MLL-rearranged leukemia) in which HOXA/PBX3 genes are overexpressed.
Asunto(s)
Regulación Leucémica de la Expresión Génica/fisiología , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Leucemia Mieloide Aguda/genética , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Animales , Células de la Médula Ósea/fisiología , Trasplante de Médula Ósea , Línea Celular Transformada , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Reordenamiento Génico/genética , Células HEK293 , N-Metiltransferasa de Histona-Lisina , Proteínas de Homeodominio/antagonistas & inhibidores , Humanos , Péptidos y Proteínas de Señalización Intercelular , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes , Proteína de la Leucemia Mieloide-Linfoide/genética , Péptidos/farmacología , Factor de Transcripción 1 de la Leucemia de Células Pre-B , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , ARN Interferente Pequeño/genética , Ratas , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Acute myeloid leukemia (AML) is a heterogeneous group of hematopoietic malignancies with variable response to treatment. AMLs bearing MLL (mixed lineage leukemia) rearrangements are associated with intermediate or poor survival. MicroRNAs (miRNAs), a class of small noncoding RNAs, have been postulated to be important gene expression regulators virtually in all biological processes, including leukemogenesis. Through a large-scale, genome-wide miRNA expression profiling assay of 85 human AML and 15 normal control samples, we show that among 48 miRNAs that are significantly differentially expressed between MLL- and non-MLL-rearranged AML samples, only one (miR-495) is expressed at a lower level in MLL-rearranged AML than in non-MLL-rearranged AML; meanwhile, miR-495 is also significantly down-regulated in MLL-rearranged AML samples compared with normal control samples. Through in vitro colony-forming/replating assays and in vivo bone marrow transplantation studies, we show that forced expression of miR-495 significantly inhibits MLL-fusion-mediated cell transformation in vitro and leukemogenesis in vivo. In human leukemic cells carrying MLL rearrangements, ectopic expression of miR-495 greatly inhibits cell viability and increases cell apoptosis. Furthermore, our studies demonstrate that PBX3 and MEIS1 are two direct target genes of miR-495, and forced expression of either of them can reverse the effects of miR-495 overexpression on inhibiting cell viability and promoting apoptosis of human MLL-rearranged leukemic cells. Thus, our data indicate that miR-495 likely functions as a tumor suppressor in AML with MLL rearrangements by targeting essential leukemia-related genes.
Asunto(s)
Regulación hacia Abajo/genética , Reordenamiento Génico/genética , Leucemia Mieloide Aguda/genética , MicroARNs/metabolismo , Proteína de la Leucemia Mieloide-Linfoide/genética , Animales , Secuencia de Bases , Estudios de Casos y Controles , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/patología , Perfilación de la Expresión Génica , Regulación Leucémica de la Expresión Génica , Genes Relacionados con las Neoplasias/genética , Estudios de Asociación Genética , Proteínas de Homeodominio/metabolismo , Humanos , Leucemia Mieloide Aguda/patología , Ratones , MicroARNs/genética , Datos de Secuencia Molecular , Proteína 1 del Sitio de Integración Viral Ecotrópica Mieloide , Proteínas de Neoplasias/metabolismo , Proteínas de Fusión Oncogénica/metabolismo , Proteínas Proto-Oncogénicas/metabolismoRESUMEN
Increased expression levels of miR-181 family members have been shown to be associated with favorable outcome in patients with cytogenetically normal acute myeloid leukemia. Here we show that increased expression of miR-181a and miR-181b is also significantly (P < .05; Cox regression) associated with favorable overall survival in cytogenetically abnormal AML (CA-AML) patients. We further show that up-regulation of a gene signature composed of 4 potential miR-181 targets (including HOXA7, HOXA9, HOXA11, and PBX3), associated with down-regulation of miR-181 family members, is an independent predictor of adverse overall survival on multivariable testing in analysis of 183 CA-AML patients. The independent prognostic impact of this 4-homeobox-gene signature was confirmed in a validation set of 271 CA-AML patients. Furthermore, our in vitro and in vivo studies indicated that ectopic expression of miR-181b significantly promoted apoptosis and inhibited viability/proliferation of leukemic cells and delayed leukemogenesis; such effects could be reversed by forced expression of PBX3. Thus, the up-regulation of the 4 homeobox genes resulting from the down-regulation of miR-181 family members probably contribute to the poor prognosis of patients with nonfavorable CA-AML. Restoring expression of miR-181b and/or targeting the HOXA/PBX3 pathways may provide new strategies to improve survival substantially.
Asunto(s)
Proteínas de Homeodominio/genética , Leucemia Mieloide/genética , MicroARNs/genética , Proteínas Proto-Oncogénicas/genética , Enfermedad Aguda , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Regulación hacia Abajo , Femenino , Perfilación de la Expresión Génica , Humanos , Lactante , Recién Nacido , Estimación de Kaplan-Meier , Leucemia Mieloide/patología , Masculino , Persona de Mediana Edad , Análisis de Secuencia por Matrices de Oligonucleótidos , Pronóstico , Regulación hacia Arriba , Adulto JovenRESUMEN
HOXA9 plays a critical role in both normal hematopoiesis and leukemogenesis, particularly in the development and maintenance of mixed lineage leukemia (MLL)-rearranged leukemia. Through reverse transcription-polymerase chain reaction (RT-PCR) analysis of HOXA9 transcripts in human leukemia and normal bone marrow samples, we identified a truncated isoform of HOXA9, namely HOXA9T, and found that both HOXA9T and canonical HOXA9 were highly expressed in leukemia cell lines bearing MLL rearrangements, relative to human normal bone marrow cells or other subtypes of leukemia cells. A frameshift in HOXA9T in exon I causes a premature stop codon upstream of the PBX-binding domain and the homeodomain, which leads to the generation of a non-homeodomain-containing protein. Unlike the canonical HOXA9, HOXA9T alone cannot transform normal bone marrow progenitor cells. Moreover, HOXA9T cannot cooperate with MEIS1 to transform cells, despite the presence of a MEIS1-binding domain. Remarkably, although the truncated isoforms of many proteins function as dominant-negative competitors or inhibitors of their full-length counterparts, this is not the case for HOXA9T; instead, HOXA9T synergized with HOXA9 in transforming mouse normal bone marrow progenitor cells through promoting self-renewal and proliferation of the cells. Collectively, our data indicate that both truncated and full-length forms of HOXA9 are highly expressed in human MLL-rearranged leukemia, and the truncated isoform of HOXA9 might also play an oncogenic role by cooperating with canonical HOXA9 in cell transformation and leukemogenesis.
Asunto(s)
Regulación Neoplásica de la Expresión Génica , Proteínas de Homeodominio/genética , Leucemia/genética , Proteínas de Neoplasias/genética , ARN Mensajero/biosíntesis , Animales , Secuencia de Bases , Médula Ósea/metabolismo , Médula Ósea/patología , Línea Celular Tumoral , Proliferación Celular , Transformación Celular Neoplásica/genética , Codón sin Sentido , Exones , Proteínas de Homeodominio/metabolismo , Humanos , Leucemia/metabolismo , Leucemia/patología , Ratones , Datos de Secuencia Molecular , Proteína 1 del Sitio de Integración Viral Ecotrópica Mieloide , Proteínas de Neoplasias/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismoRESUMEN
This corrects the article DOI: 10.1038/ncomms1681.
RESUMEN
The original version of this Article contained an error in the spelling of the author James C. Mulloy, which was incorrectly given as James Mulloy. This has now been corrected in both the PDF and HTML versions of the Article.
RESUMEN
Effective therapy of acute myeloid leukemia (AML) remains an unmet need. DNA methylcytosine dioxygenase Ten-eleven translocation 1 (TET1) is a critical oncoprotein in AML. Through a series of data analysis and drug screening, we identified two compounds (i.e., NSC-311068 and NSC-370284) that selectively suppress TET1 transcription and 5-hydroxymethylcytosine (5hmC) modification, and effectively inhibit cell viability in AML with high expression of TET1 (i.e., TET1-high AML), including AML carrying t(11q23)/MLL-rearrangements and t(8;21) AML. NSC-311068 and especially NSC-370284 significantly repressed TET1-high AML progression in vivo. UC-514321, a structural analog of NSC-370284, exhibited a more potent therapeutic effect and prolonged the median survival of TET1-high AML mice over three fold. NSC-370284 and UC-514321 both directly target STAT3/5, transcriptional activators of TET1, and thus repress TET1 expression. They also exhibit strong synergistic effects with standard chemotherapy. Our results highlight the therapeutic potential of targeting the STAT/TET1 axis by selective inhibitors in AML treatment.
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Inhibidores Enzimáticos/farmacología , Leucemia Mieloide Aguda/tratamiento farmacológico , Oxigenasas de Función Mixta/antagonistas & inhibidores , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Factor de Transcripción STAT3/antagonistas & inhibidores , Factor de Transcripción STAT5/antagonistas & inhibidores , Animales , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Línea Celular Tumoral , Daunorrubicina/administración & dosificación , Inhibidores Enzimáticos/administración & dosificación , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Humanos , Estimación de Kaplan-Meier , Leucemia Experimental/tratamiento farmacológico , Leucemia Experimental/genética , Leucemia Experimental/metabolismo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Ratones Endogámicos C57BL , Oxigenasas de Función Mixta/genética , Oxigenasas de Función Mixta/metabolismo , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Interferencia de ARN , Factor de Transcripción STAT3/genética , Factor de Transcripción STAT3/metabolismo , Factor de Transcripción STAT5/genética , Factor de Transcripción STAT5/metabolismo , Células THP-1RESUMEN
N6-Methyladenosine (m6A) represents the most prevalent internal modification in mammalian mRNAs. Despite its functional importance in various fundamental bioprocesses, the studies of m6A in cancer have been limited. Here we show that FTO, as an m6A demethylase, plays a critical oncogenic role in acute myeloid leukemia (AML). FTO is highly expressed in AMLs with t(11q23)/MLL rearrangements, t(15;17)/PML-RARA, FLT3-ITD, and/or NPM1 mutations. FTO enhances leukemic oncogene-mediated cell transformation and leukemogenesis, and inhibits all-trans-retinoic acid (ATRA)-induced AML cell differentiation, through regulating expression of targets such as ASB2 and RARA by reducing m6A levels in these mRNA transcripts. Collectively, our study demonstrates the functional importance of the m6A methylation and the corresponding proteins in cancer, and provides profound insights into leukemogenesis and drug response.
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Adenosina/análogos & derivados , Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/fisiología , Leucemia Mieloide Aguda/etiología , Adenosina/metabolismo , Apoptosis , Proliferación Celular , Humanos , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/enzimología , Leucemia Mieloide Aguda/patología , Metilación , Nucleofosmina , Receptor alfa de Ácido Retinoico/fisiología , Proteínas Supresoras de la Señalización de Citocinas/fisiología , Transcriptoma , Tretinoina/farmacologíaRESUMEN
Expression of functionally important genes is often tightly regulated at both transcriptional and post-transcriptional levels. We reported previously that TET1, the founding member of the TET methylcytosine dioxygenase family, plays an essential oncogenic role in MLL-rearranged acute myeloid leukemia (AML), where it is overexpressed owing to MLL-fusion-mediated direct up-regulation at the transcriptional level. Here we show that the overexpression of TET1 in MLL-rearranged AML also relies on the down-regulation of miR-26a, which directly negatively regulates TET1 expression at the post-transcriptional level. Through inhibiting expression of TET1 and its downstream targets, forced expression of miR-26a significantly suppresses the growth/viability of human MLL-rearranged AML cells, and substantially inhibits MLL-fusion-mediated mouse hematopoietic cell transformation and leukemogenesis. Moreover, c-Myc, an oncogenic transcription factor up-regulated in MLL-rearranged AML, mediates the suppression of miR-26a expression at the transcriptional level. Collectively, our data reveal a previously unappreciated signaling pathway involving the MLL-fusion/MYCâ£miR-26aâ£TET1 signaling circuit, in which miR-26a functions as an essential tumor-suppressor mediator and its transcriptional repression is required for the overexpression and oncogenic function of TET1 in MLL-rearranged AML. Thus, restoration of miR-26a expression/function holds therapeutic potential to treat MLL-rearranged AML.
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Proteínas de Unión al ADN/metabolismo , Fusión Génica , Reordenamiento Génico , N-Metiltransferasa de Histona-Lisina/metabolismo , Leucemia Mieloide Aguda/enzimología , MicroARNs/metabolismo , Proteína de la Leucemia Mieloide-Linfoide/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Transducción de Señal , Regiones no Traducidas 3' , Animales , Sitios de Unión , Trasplante de Médula Ósea , Línea Celular Tumoral , Proliferación Celular , Supervivencia Celular , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Transformación Celular Neoplásica/patología , Proteínas de Unión al ADN/genética , Regulación Enzimológica de la Expresión Génica , Regulación Leucémica de la Expresión Génica , N-Metiltransferasa de Histona-Lisina/genética , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patología , Ratones Endogámicos C57BL , MicroARNs/genética , Oxigenasas de Función Mixta , Proteína de la Leucemia Mieloide-Linfoide/genética , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas c-myc/genética , Factores de Tiempo , Transcripción Genética , TransfecciónRESUMEN
Overexpression of HOXA/MEIS1/PBX3 homeobox genes is the hallmark of mixed lineage leukemia (MLL)-rearranged acute myeloid leukemia (AML). HOXA9 and MEIS1 are considered to be the most critical targets of MLL fusions and their coexpression rapidly induces AML. MEIS1 and PBX3 are not individually able to transform cells and were therefore hypothesized to function as cofactors of HOXA9. However, in this study, we demonstrate that coexpression of PBX3 and MEIS1 (PBX3/MEIS1), without ectopic expression of a HOX gene, is sufficient for transformation of normal mouse hematopoietic stem/progenitor cells in vitro. Moreover, PBX3/MEIS1 overexpression also caused AML in vivo, with a leukemic latency similar to that caused by forced expression of MLL-AF9, the most common form of MLL fusions. Furthermore, gene expression profiling of hematopoietic cells demonstrated that PBX3/MEIS1 overexpression, but not HOXA9/MEIS1, HOXA9/PBX3, or HOXA9 overexpression, recapitulated the MLL-fusion-mediated core transcriptome, particularly upregulation of the endogenous Hoxa genes. Disruption of the binding between MEIS1 and PBX3 diminished PBX3/MEIS1-mediated cell transformation and HOX gene upregulation. Collectively, our studies strongly implicate the PBX3/MEIS1 interaction as a driver of cell transformation and leukemogenesis, and suggest that this axis may play a critical role in the regulation of the core transcriptional programs activated in MLL-rearranged and HOX-overexpressing AML. Therefore, targeting the MEIS1/PBX3 interaction may represent a promising therapeutic strategy to treat these AML subtypes.