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2.
Cancer Cell ; 31(1): 127-141, 2017 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-28017614

RESUMO

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.


Assuntos
Adenosina/análogos & derivados , Dioxigenase FTO Dependente de alfa-Cetoglutarato/fisiologia , Leucemia Mieloide Aguda/etiologia , Adenosina/metabolismo , Apoptose , Proliferação de Células , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/enzimologia , Leucemia Mieloide Aguda/patologia , Metilação , Nucleofosmina , Receptor alfa de Ácido Retinoico/fisiologia , Proteínas Supressoras da Sinalização de Citocina/fisiologia , Transcriptoma , Tretinoína/farmacologia
3.
Cancer Res ; 76(15): 4470-80, 2016 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-27280396

RESUMO

Acute myeloid leukemia (AML) is a common and fatal form of hematopoietic malignancy. Overexpression and/or mutations of FLT3 have been shown to occur in the majority of cases of AML. Our analysis of a large-scale AML patient cohort (N = 562) indicates that FLT3 is particularly highly expressed in some subtypes of AML, such as AML with t(11q23)/MLL-rearrangements or FLT3-ITD. Such AML subtypes are known to be associated with unfavorable prognosis. To treat FLT3-overexpressing AML, we developed a novel targeted nanoparticle system: FLT3 ligand (FLT3L)-conjugated G7 poly(amidoamine) (PAMAM) nanosized dendriplex encapsulating miR-150, a pivotal tumor suppressor and negative regulator of FLT3 We show that the FLT3L-guided miR-150 nanoparticles selectively and efficiently target FLT3-overexpressing AML cells and significantly inhibit viability/growth and promote apoptosis of the AML cells. Our proof-of-concept animal model studies demonstrate that the FLT3L-guided miR-150 nanoparticles tend to concentrate in bone marrow, and significantly inhibit progression of FLT3-overexpressing AML in vivo, while exhibiting no obvious side effects on normal hematopoiesis. Collectively, we have developed a novel targeted therapeutic strategy, using FLT3L-guided miR-150-based nanoparticles, to treat FLT3-overexpressing AML with high efficacy and minimal side effects. Cancer Res; 76(15); 4470-80. ©2016 AACR.


Assuntos
Leucemia Mieloide Aguda/genética , Proteínas de Membrana/genética , MicroRNAs/genética , Animais , Humanos , Camundongos , Mutação , Nanopartículas
4.
Nat Commun ; 7: 11452, 2016 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-27116251

RESUMO

MicroRNAs are subject to precise regulation and have key roles in tumorigenesis. In contrast to the oncogenic role of miR-22 reported in myelodysplastic syndrome (MDS) and breast cancer, here we show that miR-22 is an essential anti-tumour gatekeeper in de novo acute myeloid leukaemia (AML) where it is significantly downregulated. Forced expression of miR-22 significantly suppresses leukaemic cell viability and growth in vitro, and substantially inhibits leukaemia development and maintenance in vivo. Mechanistically, miR-22 targets multiple oncogenes, including CRTC1, FLT3 and MYCBP, and thus represses the CREB and MYC pathways. The downregulation of miR-22 in AML is caused by TET1/GFI1/EZH2/SIN3A-mediated epigenetic repression and/or DNA copy-number loss. Furthermore, nanoparticles carrying miR-22 oligos significantly inhibit leukaemia progression in vivo. Together, our study uncovers a TET1/GFI1/EZH2/SIN3A/miR-22/CREB-MYC signalling circuit and thereby provides insights into epigenetic/genetic mechanisms underlying the pathogenesis of AML, and also highlights the clinical potential of miR-22-based AML therapy.


Assuntos
Regulação Leucêmica da Expressão Gênica , Genes Supressores de Tumor , Leucemia Mieloide/genética , MicroRNAs/genética , Doença Aguda , Animais , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/genética , Regulação para Baixo , Epigênese Genética , Perfilação da Expressão Gênica , Células HEK293 , Humanos , Leucemia Mieloide/tratamento farmacológico , Leucemia Mieloide/patologia , Camundongos Endogâmicos C57BL , MicroRNAs/química , MicroRNAs/uso terapêutico , Síndromes Mielodisplásicas/genética , Síndromes Mielodisplásicas/patologia , Transdução de Sinais/genética
5.
Cancer Res ; 76(3): 619-29, 2016 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-26747896

RESUMO

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.


Assuntos
Células-Tronco Hematopoéticas/metabolismo , Histona-Lisina N-Metiltransferase/genética , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Leucemia Mieloide Aguda/genética , Proteína de Leucina Linfoide-Mieloide/genética , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Animais , Perfilação da Expressão Gênica , Rearranjo Gênico , Células-Tronco Hematopoéticas/patologia , Humanos , Leucemia Mieloide Aguda/patologia , Camundongos , Proteína Meis1 , Transcriptoma , Regulação para Cima
6.
Cancer Lett ; 372(2): 157-65, 2016 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-26791235

RESUMO

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/MYC⊣miR-26a⊣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.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Fusão Gênica , Rearranjo Gênico , Histona-Lisina N-Metiltransferase/metabolismo , Leucemia Mieloide Aguda/enzimologia , MicroRNAs/metabolismo , Proteína de Leucina Linfoide-Mieloide/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transdução de Sinais , Regiões 3' não Traduzidas , Animais , Sítios de Ligação , Transplante de Medula Óssea , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Proteínas de Ligação a DNA/genética , Regulação Enzimológica da Expressão Gênica , Regulação Leucêmica da Expressão Gênica , Histona-Lisina N-Metiltransferase/genética , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Camundongos Endogâmicos C57BL , MicroRNAs/genética , Oxigenases de Função Mista , Proteína de Leucina Linfoide-Mieloide/genética , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-myc/genética , Fatores de Tempo , Transcrição Gênica , Transfecção
7.
Blood ; 126(17): 2005-15, 2015 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-26361793

RESUMO

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.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Transformação Celular Neoplásica/patologia , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , MicroRNAs/genética , Animais , Diferenciação Celular/genética , Cromossomos Humanos Par 21/genética , Cromossomos Humanos Par 8/genética , Feminino , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/mortalidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Estadiamento de Neoplasias , Proteínas de Fusão Oncogênica/genética , Prognóstico , Taxa de Sobrevida , Translocação Genética/genética
8.
Proc Natl Acad Sci U S A ; 110(29): 11994-9, 2013 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-23818607

RESUMO

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.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Regulação Neoplásica da Expressão Gênica/fisiologia , Leucemia Mieloide Aguda/metabolismo , Proteína de Leucina Linfoide-Mieloide/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transdução de Sinais/fisiologia , 5-Metilcitosina/análogos & derivados , Imunoprecipitação da Cromatina , Cromatografia Líquida , Citosina/análogos & derivados , Citosina/metabolismo , Perfilação da Expressão Gênica , Histona-Lisina N-Metiltransferase , Proteínas de Homeodomínio/metabolismo , Humanos , Immunoblotting , Análise em Microsséries , Oxigenases de Função Mista , Proteína Meis1 , Proteínas de Neoplasias/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Transdução de Sinais/genética , Espectrometria de Massas em Tandem
9.
Proc Natl Acad Sci U S A ; 110(28): 11511-6, 2013 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-23798388

RESUMO

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.


Assuntos
Leucemia Mieloide Aguda/genética , MicroRNAs/fisiologia , Proteína de Leucina Linfoide-Mieloide/genética , Apoptose/genética , Sobrevivência Celular/genética , Proteínas de Ligação a DNA/fisiologia , Humanos , Leucemia Mieloide Aguda/patologia , Proteína do Locus do Complexo MDS1 e EVI1 , MicroRNAs/genética , Proto-Oncogenes/fisiologia , Fatores de Transcrição/fisiologia
10.
J Clin Oncol ; 31(9): 1172-81, 2013 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-23382473

RESUMO

PURPOSE: To identify a robust prognostic gene expression signature as an independent predictor of survival of patients with acute myeloid leukemia (AML) and use it to improve established risk classification. PATIENTS AND METHODS: Four independent sets totaling 499 patients with AML carrying various cytogenetic and molecular abnormalities were used as training sets. Two independent patient sets composed of 825 patients were used as validation sets. Notably, patients from different sets were treated with different protocols, and their gene expression profiles were derived using different microarray platforms. Cox regression and Kaplan-Meier methods were used for survival analyses. RESULTS: A prognostic signature composed of 24 genes was derived from a meta-analysis of Cox regression values of each gene across the four training sets. In multivariable models, a higher sum value of the 24-gene signature was an independent predictor of shorter overall (OS) and event-free survival (EFS) in both training and validation sets (P < .01). Moreover, this signature could substantially improve the European LeukemiaNet (ELN) risk classification of AML, and patients in three new risk groups classified by the integrated risk classification showed significantly (P < .001) distinct OS and EFS. CONCLUSION: Despite different treatment protocols applied to patients and use of different microarray platforms for expression profiling, a common prognostic gene signature was identified as an independent predictor of survival of patients with AML. The integrated risk classification incorporating this gene signature provides a better framework for risk stratification and outcome prediction than the ELN classification.


Assuntos
Perfilação da Expressão Gênica/métodos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/mortalidade , Humanos , Cooperação Internacional , Estimativa de Kaplan-Meier , Análise em Microsséries , Pessoa de Meia-Idade , Prognóstico , Modelos de Riscos Proporcionais
11.
Blood ; 121(8): 1422-31, 2013 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-23264595

RESUMO

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.


Assuntos
Regulação Leucêmica da Expressão Gênica/fisiologia , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Leucemia Mieloide Aguda/genética , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Animais , Células da Medula Óssea/fisiologia , Transplante de Medula Óssea , Linhagem Celular Transformada , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Regulação Leucêmica da Expressão Gênica/efeitos dos fármacos , Rearranjo Gênico/genética , Células HEK293 , Histona-Lisina N-Metiltransferase , Proteínas de Homeodomínio/antagonistas & inibidores , Humanos , Peptídeos e Proteínas de Sinalização Intercelular , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Proteína de Leucina Linfoide-Mieloide/genética , Peptídeos/farmacologia , Fator de Transcrição 1 de Leucemia de Células Pré-B , Proteínas Proto-Oncogênicas/antagonistas & inibidores , RNA Interferente Pequeno/genética , Ratos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
12.
Proc Natl Acad Sci U S A ; 109(47): 19397-402, 2012 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-23132946

RESUMO

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.


Assuntos
Regulação para Baixo/genética , Rearranjo Gênico/genética , Leucemia Mieloide Aguda/genética , MicroRNAs/metabolismo , Proteína de Leucina Linfoide-Mieloide/genética , Animais , Sequência de Bases , Estudos de Casos e Controles , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Perfilação da Expressão Gênica , Regulação Leucêmica da Expressão Gênica , Genes Neoplásicos/genética , Estudos de Associação Genética , Proteínas de Homeodomínio/metabolismo , Humanos , Leucemia Mieloide Aguda/patologia , Camundongos , MicroRNAs/genética , Dados de Sequência Molecular , Proteína Meis1 , Proteínas de Neoplasias/metabolismo , Proteínas de Fusão Oncogênica/metabolismo , Proteínas Proto-Oncogênicas/metabolismo
13.
Cancer Cell ; 22(4): 524-35, 2012 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-23079661

RESUMO

Expression of microRNAs (miRNAs) is under stringent regulation at both transcriptional and posttranscriptional levels. Disturbance at either level could cause dysregulation of miRNAs. Here, we show that MLL fusion proteins negatively regulate production of miR-150, an miRNA widely repressed in acute leukemia, by blocking miR-150 precursors from being processed to mature miRNAs through MYC/LIN28 functional axis. Forced expression of miR-150 dramatically inhibited leukemic cell growth and delayed MLL-fusion-mediated leukemogenesis, likely through targeting FLT3 and MYB and thereby interfering with the HOXA9/MEIS1/FLT3/MYB signaling network, which in turn caused downregulation of MYC/LIN28. Collectively, we revealed a MLL-fusion/MYC/LIN28⊣miR-150⊣FLT3/MYB/HOXA9/MEIS1 signaling circuit underlying the pathogenesis of leukemia, where miR-150 functions as a pivotal gatekeeper and its repression is required for leukemogenesis.


Assuntos
Leucemia/etiologia , MicroRNAs/fisiologia , Proteína de Leucina Linfoide-Mieloide/fisiologia , Proteínas Proto-Oncogênicas c-myc/fisiologia , Proteínas de Ligação a RNA/fisiologia , Animais , Linhagem Celular Tumoral , Transformação Celular Neoplásica , Metilação de DNA , Regulação para Baixo , Dosagem de Genes , Regulação Leucêmica da Expressão Gênica , Histona-Lisina N-Metiltransferase , Proteínas de Homeodomínio/fisiologia , Humanos , Camundongos , MicroRNAs/análise , MicroRNAs/antagonistas & inibidores , Mutação , Proteína Meis1 , Proteínas de Neoplasias/fisiologia , Proteínas Nucleares/genética , Transdução de Sinais , Tirosina Quinase 3 Semelhante a fms/genética
14.
Blood Cells Mol Dis ; 49(2): 102-6, 2012 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-22633751

RESUMO

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.


Assuntos
Regulação Neoplásica da Expressão Gênica , Proteínas de Homeodomínio/genética , Leucemia/genética , Proteínas de Neoplasias/genética , RNA Mensageiro/biossíntese , Animais , Sequência de Bases , Medula Óssea/metabolismo , Medula Óssea/patologia , Linhagem Celular Tumoral , Proliferação de Células , Transformação Celular Neoplásica/genética , Códon sem Sentido , Éxons , Proteínas de Homeodomínio/metabolismo , Humanos , Leucemia/metabolismo , Leucemia/patologia , Camundongos , Dados de Sequência Molecular , Proteína Meis1 , Proteínas de Neoplasias/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo
15.
Nat Commun ; 3: 688, 2012 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-22353710

RESUMO

HOXA9 and MEIS1 have essential oncogenic roles in mixed lineage leukaemia (MLL)-rearranged leukaemia. Here we show that they are direct targets of miRNA-196b, a microRNA (miRNA) located adjacent to and co-expressed with HOXA9, in MLL-rearranged leukaemic cells. Forced expression of miR-196b significantly delays MLL-fusion-mediated leukemogenesis in primary bone marrow transplantation through suppressing Hoxa9/Meis1 expression. However, ectopic expression of miR-196b results in more aggressive leukaemic phenotypes and causes much faster leukemogenesis in secondary transplantation than MLL fusion alone, likely through the further repression of Fas expression, a proapoptotic gene downregulated in MLL-rearranged leukaemia. Overexpression of FAS significantly inhibits leukemogenesis and reverses miR-196b-mediated phenotypes. Targeting Hoxa9/Meis1 and Fas by miR-196b is probably also important for normal haematopoiesis. Thus, our results uncover a previously unappreciated miRNA-regulation mechanism by which a single miRNA may target both oncogenes and tumour suppressors, simultaneously, or, sequentially, in tumourigenesis and normal development per cell differentiation, indicating that miRNA regulation is much more complex than previously thought.


Assuntos
Proteínas de Homeodomínio/metabolismo , Leucemia Mieloide Aguda/genética , MicroRNAs/metabolismo , Proteínas de Neoplasias/metabolismo , Receptor fas/metabolismo , Animais , Apoptose , Sequência de Bases , Transformação Celular Neoplásica , Células Cultivadas , Feminino , Regulação Neoplásica da Expressão Gênica , Genes Supressores de Tumor , Hematopoese/genética , Proteínas de Homeodomínio/genética , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/biossíntese , Proteína Meis1 , Proteína de Leucina Linfoide-Mieloide/biossíntese , Proteína de Leucina Linfoide-Mieloide/genética , Proteínas de Neoplasias/genética , Análise de Sequência de DNA
16.
Blood ; 119(10): 2314-24, 2012 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-22251480

RESUMO

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.


Assuntos
Proteínas de Homeodomínio/genética , Leucemia Mieloide/genética , MicroRNAs/genética , Proteínas Proto-Oncogênicas/genética , Doença Aguda , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Regulação para Baixo , Feminino , Perfilação da Expressão Gênica , Humanos , Lactente , Recém-Nascido , Estimativa de Kaplan-Meier , Leucemia Mieloide/patologia , Masculino , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos , Prognóstico , Regulação para Cima , Adulto Jovem
17.
Proc Natl Acad Sci U S A ; 107(8): 3710-5, 2010 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-20133587

RESUMO

MicroRNA (miRNA)-17-92 cluster (miR-17-92), containing seven individual miRNAs, is frequently amplified and overexpressed in lymphomas and various solid tumors. We have found that it is also frequently amplified and the miRNAs are aberrantly overexpressed in mixed lineage leukemia (MLL)-rearranged acute leukemias. Furthermore, we show that MLL fusions exhibit a much stronger direct binding to the locus of this miRNA cluster than does wild-type MLL; these changes are associated with elevated levels of histone H3 acetylation and H3K4 trimethylation and an up-regulation of these miRNAs. We further observe that forced expression of this miRNA cluster increases proliferation and inhibits apoptosis of human cells. More importantly, we show that this miRNA cluster can significantly increase colony-forming capacity of normal mouse bone marrow progenitor cells alone and, particularly, in cooperation with MLL fusions. Finally, through combinatorial analysis of miRNA and mRNA arrays of mouse bone marrow progenitor cells transfected with this miRNA cluster and/or MLL fusion gene, we identified 363 potential miR-17-92 target genes that exhibited a significant inverse correlation of expression with the miRNAs. Remarkably, these potential target genes are significantly enriched (P < 0.01; >2-fold) in cell differentiation, hematopoiesis, cell cycle, and apoptosis. Taken together, our studies suggest that overexpression of miR-17-92 cluster in MLL-rearranged leukemias is likely attributed to both DNA copy number amplification and direct up-regulation by MLL fusions, and that the miRNAs in this cluster may play an essential role in the development of MLL-associated leukemias through inhibiting cell differentiation and apoptosis, while promoting cell proliferation, by regulating relevant target genes.


Assuntos
Regulação Leucêmica da Expressão Gênica , Leucemia Mieloide Aguda/genética , MicroRNAs/biossíntese , Animais , Linhagem Celular Tumoral , Epigênese Genética , Células HeLa , Humanos , Camundongos , MicroRNAs/genética , Família Multigênica
18.
Cancer Res ; 69(3): 1109-16, 2009 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-19155294

RESUMO

Important biological and pathologic properties are often conserved across species. Although several mouse leukemia models have been well established, the genes deregulated in both human and murine leukemia cells have not been studied systematically. We performed a serial analysis of gene expression in both human and murine MLL-ELL or MLL-ENL leukemia cells and identified 88 genes that seemed to be significantly deregulated in both types of leukemia cells, including 57 genes not reported previously as being deregulated in MLL-associated leukemias. These changes were validated by quantitative PCR. The most up-regulated genes include several HOX genes (e.g., HOX A5, HOXA9, and HOXA10) and MEIS1, which are the typical hallmark of MLL rearrangement leukemia. The most down-regulated genes include LTF, LCN2, MMP9, S100A8, S100A9, PADI4, TGFBI, and CYBB. Notably, the up-regulated genes are enriched in gene ontology terms, such as gene expression and transcription, whereas the down-regulated genes are enriched in signal transduction and apoptosis. We showed that the CpG islands of the down-regulated genes are hypermethylated. We also showed that seven individual microRNAs (miRNA) from the mir-17-92 cluster, which are overexpressed in human MLL rearrangement leukemias, are also consistently overexpressed in mouse MLL rearrangement leukemia cells. Nineteen possible targets of these miRNAs were identified, and two of them (i.e., APP and RASSF2) were confirmed further by luciferase reporter and mutagenesis assays. The identification and validation of consistent changes of gene expression in human and murine MLL rearrangement leukemias provide important insights into the genetic base for MLL-associated leukemogenesis.


Assuntos
Regulação Leucêmica da Expressão Gênica , Leucemia Mieloide/genética , Proteína de Leucina Linfoide-Mieloide/genética , Proteínas de Fusão Oncogênica/genética , Animais , Metilação de DNA , Perfilação da Expressão Gênica , Rearranjo Gênico , Histona-Lisina N-Metiltransferase , Humanos , Leucemia Mieloide/patologia , Camundongos , MicroRNAs/genética , Células Progenitoras Mieloides/patologia , Proteína de Leucina Linfoide-Mieloide/biossíntese , Proteínas de Fusão Oncogênica/biossíntese , Reação em Cadeia da Polimerase/métodos
19.
Proc Natl Acad Sci U S A ; 105(40): 15535-40, 2008 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-18832181

RESUMO

MicroRNAs (miRNAs) are postulated to be important regulators in cancers. Here, we report a genome-wide miRNA expression analysis in 52 acute myeloid leukemia (AML) samples with common translocations, including t(8;21)/AML1(RUNX1)-ETO(RUNX1T1), inv(16)/CBFB-MYH11, t(15;17)/PML-RARA, and MLL rearrangements. Distinct miRNA expression patterns were observed for t(15;17), MLL rearrangements, and core-binding factor (CBF) AMLs including both t(8;21) and inv(16) samples. Expression signatures of a minimum of two (i.e., miR-126/126*), three (i.e., miR-224, miR-368, and miR-382), and seven (miR-17-5p and miR-20a, plus the aforementioned five) miRNAs could accurately discriminate CBF, t(15;17), and MLL-rearrangement AMLs, respectively, from each other. We further showed that the elevated expression of miR-126/126* in CBF AMLs was associated with promoter demethylation but not with amplification or mutation of the genomic locus. Our gain- and loss-of-function experiments showed that miR-126/126* inhibited apoptosis and increased the viability of AML cells and enhanced the colony-forming ability of mouse normal bone marrow progenitor cells alone and particularly, in cooperation with AML1-ETO, likely through targeting Polo-like kinase 2 (PLK2), a tumor suppressor. Our results demonstrate that specific alterations in miRNA expression distinguish AMLs with common translocations and imply that the deregulation of specific miRNAs may play a role in the development of leukemia with these associated genetic rearrangements.


Assuntos
Leucemia Mieloide Aguda/genética , MicroRNAs/metabolismo , Translocação Genética , Animais , Apoptose , Sobrevivência Celular , Fatores de Ligação ao Core/genética , Perfilação da Expressão Gênica , Humanos , Camundongos , Mutação , Proteínas Serina-Treonina Quinases/metabolismo
20.
Proc Natl Acad Sci U S A ; 104(50): 19971-6, 2007 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-18056805

RESUMO

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer, whereas acute myeloid leukemia (AML) is the most common acute leukemia in adults. In general, ALL has a better prognosis than AML. To understand the distinct mechanisms in leukemogenesis between ALL and AML and to identify markers for diagnosis and treatment, we performed a large-scale genome-wide microRNA (miRNA, miR) expression profiling assay and identified 27 miRNAs that are differentially expressed between ALL and AML. Among them, miR-128a and -128b are significantly overexpressed, whereas let-7b and miR-223 are significantly down-regulated in ALL compared with AML. They are the most discriminatory miRNAs between ALL and AML. Using the expression signatures of a minimum of two of these miRNAs resulted in an accuracy rate of >95% in the diagnosis of ALL and AML. The differential expression patterns of these four miRNAs were validated further through large-scale real-time PCR on 98 acute leukemia samples covering most of the common cytogenetic subtypes, along with 10 normal control samples. Furthermore, we found that overexpression of miR-128 in ALL was at least partly associated with promoter hypomethylation and not with an amplification of its genomic locus. Taken together, we showed that expression signatures of as few as two miRNAs could accurately discriminate ALL from AML, and that epigenetic regulation might play an important role in the regulation of expression of miRNAs in acute leukemias.


Assuntos
Regulação Neoplásica da Expressão Gênica/genética , Leucemia Mieloide Aguda/genética , MicroRNAs/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Linhagem Celular Tumoral , DNA/genética , Epigênese Genética/genética , Amplificação de Genes/genética , Perfilação da Expressão Gênica , Humanos , Leucemia Mieloide Aguda/diagnóstico , Reação em Cadeia da Polimerase , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico
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