RESUMO
B lymphocyte development and selection are central to adaptive immunity and self-tolerance. These processes require B cell receptor (BCR) signaling and occur in bone marrow, an environment with variable hypoxia, but whether hypoxia-inducible factor (HIF) is involved is unknown. We show that HIF activity is high in human and murine bone marrow pro-B and pre-B cells and decreases at the immature B cell stage. This stage-specific HIF suppression is required for normal B cell development because genetic activation of HIF-1α in murine B cells led to reduced repertoire diversity, decreased BCR editing and developmental arrest of immature B cells, resulting in reduced peripheral B cell numbers. HIF-1α activation lowered surface BCR, CD19 and B cell-activating factor receptor and increased expression of proapoptotic BIM. BIM deletion rescued the developmental block. Administration of a HIF activator in clinical use markedly reduced bone marrow and transitional B cells, which has therapeutic implications. Together, our work demonstrates that dynamic regulation of HIF-1α is essential for normal B cell development.
Assuntos
Linfócitos B/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Linfopoese/genética , Animais , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/metabolismo , Linfócitos B/citologia , Linfócitos B/imunologia , Biomarcadores , Regulação da Expressão Gênica , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Cadeias Leves de Imunoglobulina/genética , Imunofenotipagem , Camundongos , Camundongos Knockout , Edição de RNA , Receptores de Antígenos de Linfócitos B/metabolismo , Transdução de Sinais , Ativação TranscricionalRESUMO
DDX3X is a ubiquitously expressed RNA helicase involved in multiple stages of RNA biogenesis. DDX3X is frequently mutated in Burkitt lymphoma, but the functional basis for this is unknown. Here, we show that loss-of-function DDX3X mutations are also enriched in MYC-translocated diffuse large B cell lymphoma and reveal functional cooperation between mutant DDX3X and MYC. DDX3X promotes the translation of mRNA encoding components of the core translational machinery, thereby driving global protein synthesis. Loss-of-function DDX3X mutations moderate MYC-driven global protein synthesis, thereby buffering MYC-induced proteotoxic stress during early lymphomagenesis. Established lymphoma cells restore full protein synthetic capacity by aberrant expression of DDX3Y, a Y chromosome homolog, the expression of which is normally restricted to the testis. These findings show that DDX3X loss of function can buffer MYC-driven proteotoxic stress and highlight the capacity of male B cell lymphomas to then compensate for this loss by ectopic DDX3Y expression.
Assuntos
Linfócitos B/enzimologia , RNA Helicases DEAD-box/metabolismo , Linfoma de Células B/enzimologia , Antígenos de Histocompatibilidade Menor/metabolismo , Proteínas de Neoplasias/biossíntese , Proteínas Proto-Oncogênicas c-myc/metabolismo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Linfócitos B/patologia , Linhagem Celular Tumoral , Criança , Pré-Escolar , RNA Helicases DEAD-box/genética , Estresse do Retículo Endoplasmático , Feminino , Regulação Enzimológica da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Mutação com Perda de Função , Linfoma de Células B/genética , Linfoma de Células B/patologia , Masculino , Camundongos Transgênicos , Pessoa de Meia-Idade , Antígenos de Histocompatibilidade Menor/genética , Proteínas de Neoplasias/genética , Biossíntese de Proteínas , Proteoma , Proteostase , Proteínas Proto-Oncogênicas c-myc/genética , Adulto JovemRESUMO
ABSTRACT: Although NPM1-mutated acute myeloid leukemia (AML) carries a generally favorable prognosis, many patients still relapse and die. Previous studies identified several molecular and clinical features associated with poor outcomes; however, only FLT3-internal tandem duplication (ITD) mutation and adverse karyotype are currently used for risk stratification because of inconsistent results and uncertainty about how other factors should influence treatment, particularly given the strong prognostic effect of postinduction measurable residual disease (MRD). Here, we analyzed a large group of patients with NPM1 mutations (NPM1mut) AML enrolled in prospective trials (National Cancer Research Institute [NCRI] AML17 and AML19, n = 1357) to delineate the impact of baseline molecular and clinical features, postinduction MRD status, and treatment intensity on the outcome. FLT3-ITD (hazard ratio [HR], 1.28; 95% confidence interval [CI], 1.01-1.63), DNMT3A (HR, 1.65; 95% CI, 1.32-2.05), WT1 (HR, 1.74; 95% CI, 1.27-2.38), and non-ABD NPM1mut (HR, 1.64; 95% CI, 1.22-2.21) were independently associated with poorer overall survival (OS). These factors were also strongly associated with MRD positivity. For patients who achieved MRD negativity, these mutations (except FLT3-ITD) were associated with an increased cumulative incidence of relapse (CIR) and poorer OS. However, apart from the few patients with adverse cytogenetics, we could not identify any group of MRD-negative patients with a CIR >40% or with benefit from allograft in first remission. Intensified chemotherapy with the FLAG-Ida (fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin) regimen was associated with improved outcomes in all subgroups, with greater benefits observed in the high-risk molecular subgroups.
Assuntos
Leucemia Mieloide Aguda , Mutação , Proteínas Nucleares , Nucleofosmina , Tirosina Quinase 3 Semelhante a fms , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/terapia , Leucemia Mieloide Aguda/mortalidade , Leucemia Mieloide Aguda/tratamento farmacológico , Proteínas Nucleares/genética , Pessoa de Meia-Idade , Feminino , Masculino , Adulto , Idoso , Tirosina Quinase 3 Semelhante a fms/genética , Prognóstico , Adulto Jovem , Neoplasia Residual/genética , DNA Metiltransferase 3A , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Proteínas WT1/genética , DNA (Citosina-5-)-Metiltransferases/genética , Adolescente , Resultado do Tratamento , Idoso de 80 Anos ou maisRESUMO
HOXA9 is commonly upregulated in acute myeloid leukemia (AML), in which it confers a poor prognosis. Characterizing the protein interactome of endogenous HOXA9 in human AML, we identified a chromatin complex of HOXA9 with the nuclear matrix attachment protein SAFB. SAFB perturbation phenocopied HOXA9 knockout to decrease AML proliferation, increase differentiation and apoptosis in vitro, and prolong survival in vivo. Integrated genomic, transcriptomic, and proteomic analyses further demonstrated that the HOXA9-SAFB (H9SB)-chromatin complex associates with nucleosome remodeling and histone deacetylase (NuRD) and HP1γ to repress the expression of factors associated with differentiation and apoptosis, including NOTCH1, CEBPδ, S100A8, and CDKN1A. Chemical or genetic perturbation of NuRD and HP1γ-associated catalytic activity also triggered differentiation, apoptosis, and the induction of these tumor-suppressive genes. Importantly, this mechanism is operative in other HOXA9-dependent AML genotypes. This mechanistic insight demonstrates the active HOXA9-dependent differentiation block as a potent mechanism of disease maintenance in AML that may be amenable to therapeutic intervention by targeting the H9SB interface and/or NuRD and HP1γ activity.
Assuntos
Leucemia Mieloide Aguda , Proteínas de Ligação à Região de Interação com a Matriz , Humanos , Proteômica , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Leucemia Mieloide Aguda/tratamento farmacológico , Fatores de Transcrição/genética , Proteínas Associadas à Matriz Nuclear , Cromatina , Receptores de Estrogênio/genética , Receptores de Estrogênio/uso terapêutico , Proteínas de Ligação à Região de Interação com a Matriz/genéticaRESUMO
The accessibility of cell surface proteins makes them tractable for targeting by cancer immunotherapy, but identifying suitable targets remains challenging. Here we describe plasma membrane profiling of primary human myeloma cells to identify an unprecedented number of cell surface proteins of a primary cancer. We used a novel approach to prioritize immunotherapy targets and identified a cell surface protein not previously implicated in myeloma, semaphorin-4A (SEMA4A). Using knock-down by short-hairpin RNA and CRISPR/nuclease-dead Cas9 (dCas9), we show that expression of SEMA4A is essential for normal myeloma cell growth in vitro, indicating that myeloma cells cannot downregulate the protein to avoid detection. We further show that SEMA4A would not be identified as a myeloma therapeutic target by standard CRISPR/Cas9 knockout screens because of exon skipping. Finally, we potently and selectively targeted SEMA4A with a novel antibody-drug conjugate in vitro and in vivo.
Assuntos
Mieloma Múltiplo , Semaforinas , Membrana Celular/metabolismo , Humanos , Fatores Imunológicos , Imunoterapia , Proteínas de Membrana , Mieloma Múltiplo/genética , Mieloma Múltiplo/terapia , Proteômica , Semaforinas/genética , Semaforinas/metabolismoRESUMO
Haematopoietic stem cells drive blood production, but their population size and lifetime dynamics have not been quantified directly in humans. Here we identified 129,582 spontaneous, genome-wide somatic mutations in 140 single-cell-derived haematopoietic stem and progenitor colonies from a healthy 59-year-old man and applied population-genetics approaches to reconstruct clonal dynamics. Cell divisions from early embryogenesis were evident in the phylogenetic tree; all blood cells were derived from a common ancestor that preceded gastrulation. The size of the stem cell population grew steadily in early life, reaching a stable plateau by adolescence. We estimate the numbers of haematopoietic stem cells that are actively making white blood cells at any one time to be in the range of 50,000-200,000. We observed adult haematopoietic stem cell clones that generate multilineage outputs, including granulocytes and B lymphocytes. Harnessing naturally occurring mutations to report the clonal architecture of an organ enables the high-resolution reconstruction of somatic cell dynamics in humans.
Assuntos
Células Sanguíneas/citologia , Células Sanguíneas/metabolismo , Linhagem da Célula/genética , Análise Mutacional de DNA , Mutação , Células-Tronco Adultas/citologia , Teorema de Bayes , Contagem de Células , Divisão Celular , Células Clonais/citologia , Células Clonais/metabolismo , Desenvolvimento Embrionário/genética , Genoma Humano/genética , Granulócitos/citologia , Granulócitos/metabolismo , Hematopoese/genética , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/metabolismo , Humanos , Linfócitos/citologia , Linfócitos/metabolismo , Masculino , Pessoa de Meia-Idade , Fatores de TempoRESUMO
Mutations of the tricarboxylic acid cycle enzyme fumarate hydratase cause hereditary leiomyomatosis and renal cell cancer. Fumarate hydratase-deficient renal cancers are highly aggressive and metastasize even when small, leading to a very poor clinical outcome. Fumarate, a small molecule metabolite that accumulates in fumarate hydratase-deficient cells, plays a key role in cell transformation, making it a bona fide oncometabolite. Fumarate has been shown to inhibit α-ketoglutarate-dependent dioxygenases that are involved in DNA and histone demethylation. However, the link between fumarate accumulation, epigenetic changes, and tumorigenesis is unclear. Here we show that loss of fumarate hydratase and the subsequent accumulation of fumarate in mouse and human cells elicits an epithelial-to-mesenchymal-transition (EMT), a phenotypic switch associated with cancer initiation, invasion, and metastasis. We demonstrate that fumarate inhibits Tet-mediated demethylation of a regulatory region of the antimetastatic miRNA cluster mir-200ba429, leading to the expression of EMT-related transcription factors and enhanced migratory properties. These epigenetic and phenotypic changes are recapitulated by the incubation of fumarate hydratase-proficient cells with cell-permeable fumarate. Loss of fumarate hydratase is associated with suppression of miR-200 and the EMT signature in renal cancer and is associated with poor clinical outcome. These results imply that loss of fumarate hydratase and fumarate accumulation contribute to the aggressive features of fumarate hydratase-deficient tumours.
Assuntos
Epigênese Genética , Transição Epitelial-Mesenquimal , Fumaratos/metabolismo , Animais , Movimento Celular , Células Cultivadas , Fumarato Hidratase/deficiência , Fumarato Hidratase/genética , Fumarato Hidratase/metabolismo , Células HEK293 , Humanos , Neoplasias Renais/genética , Neoplasias Renais/patologia , Mesoderma/metabolismo , Camundongos , MicroRNAs/genética , Fatores de Transcrição/metabolismo , TranscriptomaRESUMO
Interferons (IFNs) represent an important host defense against viruses. Type I IFNs induce JAK-STAT signaling and expression of IFN-stimulated genes (ISGs), which mediate antiviral activity. Histone deacetylases (HDACs) perform multiple functions in regulating gene expression and some class I HDACs and the class IV HDAC, HDAC11, influence type I IFN signaling. Here, HDAC4, a class II HDAC, is shown to promote type I IFN signaling and coprecipitate with STAT2. Pharmacological inhibition of class II HDAC activity, or knockout of HDAC4 from HEK-293T and HeLa cells, caused a defective response to IFN-α. This defect in HDAC4-/- cells was rescued by reintroduction of HDAC4 or catalytically inactive HDAC4, but not HDAC1 or HDAC5. ChIP analysis showed HDAC4 was recruited to ISG promoters following IFN stimulation and was needed for binding of STAT2 to these promoters. The biological importance of HDAC4 as a virus restriction factor was illustrated by the observations that (i) the replication and spread of vaccinia virus (VACV) and herpes simplex virus type 1 (HSV-1) were enhanced in HDAC4-/- cells and inhibited by overexpression of HDAC4; and (ii) HDAC4 is targeted for proteasomal degradation during VACV infection by VACV protein C6, a multifunctional IFN antagonist that coprecipitates with HDAC4 and is necessary and sufficient for HDAC4 degradation.
Assuntos
Vírus de DNA/metabolismo , Histona Desacetilases/metabolismo , Interferon Tipo I/metabolismo , Proteínas Repressoras/metabolismo , Transdução de Sinais/fisiologia , Vaccinia virus/metabolismo , Vacínia/metabolismo , Proteínas Virais/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Células HEK293 , Células HeLa , Herpesvirus Humano 1/metabolismo , Humanos , Vacínia/virologia , Replicação Viral/fisiologiaRESUMO
Sialic acid-binding immunoglobulin-like lectin (Siglec)-15 has recently been identified as a critical tumour checkpoint, augmenting the expression and function of programmed death-ligand 1. We raised a monoclonal antibody, A9E8, specific for Siglec-15 using phage display. A9E8 stained myeloid leukaemia cell lines and peripheral cluster of differentiation (CD)33+ blasts and CD34+ leukaemia stem cells from patients with acute myeloid leukaemia (AML). By contrast, there was minimal expression on healthy donor leucocytes or CD34+ stem cells from non-AML donors, suggesting targeting Siglec-15 may have significant therapeutic advantages over its fellow Siglec CD33. After binding, A9E8 was rapidly internalised (half-life of 180 s) into K562 cells. Antibodies to Siglec-15 therefore hold therapeutic potential for AML treatment.
Assuntos
Antígenos de Neoplasias/metabolismo , Imunoglobulinas/metabolismo , Leucemia Mieloide Aguda/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Neoplasias/metabolismo , Células-Tronco Neoplásicas/metabolismo , Antígenos CD34/metabolismo , Feminino , Humanos , Células K562 , MasculinoRESUMO
Management of chronic myeloid leukaemia (CML) has recently undergone dramatic changes, prompting the European LeukemiaNet (ELN) to issue recommendations in 2013; however, it remains unclear whether real-world CML management is consistent with these goals. We report results of UK TARGET CML, a retrospective observational study of 257 patients with chronic-phase CML who had been prescribed a first-line TKI between 2013 and 2017, most of whom received first-line imatinib (n = 203). Although 44% of patients required ≥1 change of TKI, these real-world data revealed that molecular assessments were frequently missed, 23% of patients with ELN-defined treatment failure did not switch TKI, and kinase domain mutation analysis was performed in only 49% of patients who switched TKI for resistance. Major molecular response (MMR; BCR-ABL1IS ≤0·1%) and deep molecular response (DMR; BCR-ABL1IS ≤0·01%) were observed in 50% and 29%, respectively, of patients treated with first-line imatinib, and 63% and 54%, respectively, receiving a second-generation TKI first line. MMR and DMR were also observed in 77% and 44% of evaluable patients with ≥13 months follow-up, receiving a second-generation TKI second line. We found little evidence that cardiovascular risk factors were considered during TKI management. These findings highlight key areas for improvement in providing optimal care to patients with CML.
Assuntos
Mesilato de Imatinib/uso terapêutico , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Adulto , Gerenciamento Clínico , Feminino , Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/epidemiologia , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Resultado do Tratamento , Reino Unido/epidemiologiaRESUMO
Cohesin complex disruption alters gene expression, and cohesin mutations are common in myeloid neoplasia, suggesting a critical role in hematopoiesis. Here, we explore cohesin dynamics and regulation of hematopoietic stem cell homeostasis and differentiation. Cohesin binding increases at active regulatory elements only during erythroid differentiation. Prior binding of the repressive Ets transcription factor Etv6 predicts cohesin binding at these elements and Etv6 interacts with cohesin at chromatin. Depletion of cohesin severely impairs erythroid differentiation, particularly at Etv6-prebound loci, but augments self-renewal programs. Together with corroborative findings in acute myeloid leukemia and myelodysplastic syndrome patient samples, these data suggest cohesin-mediated alleviation of Etv6 repression is required for dynamic expression at critical erythroid genes during differentiation and how this may be perturbed in myeloid malignancies.
Assuntos
Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Regulação Leucêmica da Expressão Gênica , Mutação , Transtornos Mieloproliferativos/genética , Transtornos Mieloproliferativos/metabolismo , Biomarcadores Tumorais , Linhagem Celular Tumoral , Feminino , Dosagem de Genes , Células-Tronco Hematopoéticas/metabolismo , Células-Tronco Hematopoéticas/patologia , Histonas/metabolismo , Humanos , Masculino , Transtornos Mieloproliferativos/diagnóstico , Gradação de Tumores , Ligação Proteica , Proteínas Proto-Oncogênicas c-ets/metabolismo , Sequências Reguladoras de Ácido Nucleico , Proteínas Repressoras/metabolismo , Coesinas , Variante 6 da Proteína do Fator de Translocação ETSRESUMO
Bromodomain and extra terminal protein (BET) inhibitors are first-in-class targeted therapies that deliver a new therapeutic opportunity by directly targeting bromodomain proteins that bind acetylated chromatin marks. Early clinical trials have shown promise, especially in acute myeloid leukaemia, and therefore the evaluation of resistance mechanisms is crucial to optimize the clinical efficacy of these drugs. Here we use primary mouse haematopoietic stem and progenitor cells immortalized with the fusion protein MLL-AF9 to generate several single-cell clones that demonstrate resistance, in vitro and in vivo, to the prototypical BET inhibitor, I-BET. Resistance to I-BET confers cross-resistance to chemically distinct BET inhibitors such as JQ1, as well as resistance to genetic knockdown of BET proteins. Resistance is not mediated through increased drug efflux or metabolism, but is shown to emerge from leukaemia stem cells both ex vivo and in vivo. Chromatin-bound BRD4 is globally reduced in resistant cells, whereas the expression of key target genes such as Myc remains unaltered, highlighting the existence of alternative mechanisms to regulate transcription. We demonstrate that resistance to BET inhibitors, in human and mouse leukaemia cells, is in part a consequence of increased Wnt/ß-catenin signalling, and negative regulation of this pathway results in restoration of sensitivity to I-BET in vitro and in vivo. Together, these findings provide new insights into the biology of acute myeloid leukaemia, highlight potential therapeutic limitations of BET inhibitors, and identify strategies that may enhance the clinical utility of these unique targeted therapies.
Assuntos
Benzodiazepinas/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/metabolismo , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/patologia , Proteínas Nucleares/antagonistas & inibidores , Fatores de Transcrição/antagonistas & inibidores , Animais , Azepinas/farmacologia , Proteínas de Ciclo Celular , Linhagem Celular Tumoral , Células Cultivadas , Cromatina/metabolismo , Células Clonais/efeitos dos fármacos , Células Clonais/metabolismo , Células Clonais/patologia , Resistencia a Medicamentos Antineoplásicos/genética , Epigênese Genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Genes myc/genética , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/efeitos dos fármacos , Células-Tronco Hematopoéticas/metabolismo , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Camundongos , Terapia de Alvo Molecular , Células-Tronco Neoplásicas/metabolismo , Proteínas Nucleares/metabolismo , Fatores de Transcrição/metabolismo , Transcrição Gênica/efeitos dos fármacos , Triazóis/farmacologia , Via de Sinalização Wnt/efeitos dos fármacos , beta Catenina/metabolismoRESUMO
FLT3 internal tandem duplication (FLT3ITD) mutations are common in acute myeloid leukemia (AML) associated with poor patient prognosis. Although new-generation FLT3 tyrosine kinase inhibitors (TKI) have shown promising results, the outcome of FLT3ITD AML patients remains poor and demands the identification of novel, specific, and validated therapeutic targets for this highly aggressive AML subtype. Utilizing an unbiased genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 screen, we identify GLS, the first enzyme in glutamine metabolism, as synthetically lethal with FLT3-TKI treatment. Using complementary metabolomic and gene-expression analysis, we demonstrate that glutamine metabolism, through its ability to support both mitochondrial function and cellular redox metabolism, becomes a metabolic dependency of FLT3ITD AML, specifically unmasked by FLT3-TKI treatment. We extend these findings to AML subtypes driven by other tyrosine kinase (TK) activating mutations and validate the role of GLS as a clinically actionable therapeutic target in both primary AML and in vivo models. Our work highlights the role of metabolic adaptations as a resistance mechanism to several TKI and suggests glutaminolysis as a therapeutically targetable vulnerability when combined with specific TKI in FLT3ITD and other TK activating mutation-driven leukemias.
Assuntos
Glutamina/metabolismo , Leucemia Mieloide Aguda , Mutação , Inibidores de Proteínas Quinases/farmacologia , Tirosina Quinase 3 Semelhante a fms , Sistemas CRISPR-Cas , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/genética , Estudo de Associação Genômica Ampla , Glutamina/genética , Humanos , Células K562 , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/enzimologia , Leucemia Mieloide Aguda/genética , Células THP-1 , Tirosina Quinase 3 Semelhante a fms/antagonistas & inibidores , Tirosina Quinase 3 Semelhante a fms/genética , Tirosina Quinase 3 Semelhante a fms/metabolismoRESUMO
PURPOSE OF REVIEW: The field of acute myeloid leukemia (AML) has been revolutionized in recent years by the advent of high-throughput techniques, such as next-generation sequencing. In this review, we will discuss some of the recently identified mutations that have defined a new molecular landscape in this disease, as well as their prognostic, predictive, and therapeutic implications. RECENT FINDINGS: Recent studies have shown how many cases of AML evolve from a premalignant period of latency characterized by the accumulation of several mutations and the emergence of one or multiple dominant clones. The pattern of co-occurring mutations and cytogenetic abnormalities at diagnosis defines risk and can determine therapeutic approaches to induce remission. Besides the genetic landscape at diagnosis, the continued presence of particular gene mutations during or after treatment carries prognostic information that should further influence strategies to maintain remission in the long term. The recent progress made in AML research is a seminal example of how basic science can translate into improving clinical practice. Our ability to characterize the genomic landscape of individual patients has not only improved our ability to diagnose and prognosticate but is also bringing the promise of precision medicine to fruition in the field.
Assuntos
Leucemia Mieloide Aguda/genética , Aberrações Cromossômicas , Humanos , Leucemia Mieloide Aguda/mortalidade , Leucemia Mieloide Aguda/terapia , Mutação , Proteínas Nucleares/genética , Nucleofosmina , Prognóstico , Tirosina Quinase 3 Semelhante a fms/genéticaRESUMO
Over the last decade transcriptional dysregulation and altered epigenetic programs have emerged as a hallmark in the majority of hematological cancers. Several epigenetic regulators are recurrently mutated in many hematological malignancies. In addition, in those cases that lack epigenetic mutations, altered function of epigenetic regulators has been shown to play a central role in the pathobiology of many hematological neoplasms, through mechanisms that are becoming increasingly understood. This, in turn, has led to the development of small molecule inhibitors of dysregulated epigenetic pathways as novel targeted therapies for hematological malignancies. In this review, we will present the most recent advances in our understanding of the role played by dysregulated epigenetic programs in the development and maintenance of hematological neoplasms. We will describe novel therapeutics targeting altered epigenetic programs and outline their mode of action. We will then discuss their use in specific conditions, identify potential limitations and putative toxicities while also providing an update on their current clinical development. Finally, we will highlight the opportunities presented by epigenetically targeted therapies in hematological malignancies and introduce the challenges that need to be tackled by both the research and clinical communities to best translate these novel therapies into clinical practice and to improve patient outcomes.
Assuntos
Metilação de DNA , Epigênese Genética , Regulação Neoplásica da Expressão Gênica , Neoplasias Hematológicas/genética , Animais , Neoplasias Hematológicas/patologia , HumanosRESUMO
Recent major advances in understanding the molecular basis of acute myeloid leukemia (AML) provide a double-edged sword. Although defining the topology and key features of the molecular landscape are fundamental to development of novel treatment approaches and provide opportunities for greater individualization of therapy, confirmation of the genetic complexity presents a huge challenge to successful translation into routine clinical practice. It is now clear that many genes are recurrently mutated in AML; moreover, individual leukemias harbor multiple mutations and are potentially composed of subclones with differing mutational composition, rendering each patient's AML genetically unique. In order to make sense of the overwhelming mutational data and capitalize on this clinically, it is important to identify (1) critical AML-defining molecular abnormalities that distinguish biological disease entities; (2) mutations, typically arising in subclones, that may influence prognosis but are unlikely to be ideal therapeutic targets; (3) mutations associated with preleukemic clones; and (4) mutations that have been robustly shown to confer independent prognostic information or are therapeutically relevant. The reward of identifying AML-defining molecular lesions present in all leukemic populations (including subclones) has been exemplified by acute promyelocytic leukemia, where successful targeting of the underlying PML-RARα oncoprotein has eliminated the need for chemotherapy for disease cure. Despite the molecular heterogeneity and recognizing that treatment options for other forms of AML are limited, this review will consider the scope for using novel molecular information to improve diagnosis, identify subsets of patients eligible for targeted therapies, refine outcome prediction, and track treatment response.
Assuntos
Antineoplásicos/uso terapêutico , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/tratamento farmacológico , Terapia de Alvo Molecular , Adulto , Humanos , Prognóstico , Adulto JovemRESUMO
The diagnosis of hematologic malignancies relies on multidisciplinary workflows involving morphology, flow cytometry, cytogenetic, and molecular genetic analyses. Advances in cancer genomics have identified numerous recurrent mutations with clear prognostic and/or therapeutic significance to different cancers. In myeloid malignancies, there is a clinical imperative to test for such mutations in mainstream diagnosis; however, progress toward this has been slow and piecemeal. Here we describe Karyogene, an integrated targeted resequencing/analytical platform that detects nucleotide substitutions, insertions/deletions, chromosomal translocations, copy number abnormalities, and zygosity changes in a single assay. We validate the approach against 62 acute myeloid leukemia, 50 myelodysplastic syndrome, and 40 blood DNA samples from individuals without evidence of clonal blood disorders. We demonstrate robust detection of sequence changes in 49 genes, including difficult-to-detect mutations such as FLT3 internal-tandem and mixed-lineage leukemia (MLL) partial-tandem duplications, and clinically significant chromosomal rearrangements including MLL translocations to known and unknown partners, identifying the novel fusion gene MLL-DIAPH2 in the process. Additionally, we identify most significant chromosomal gains and losses, and several copy neutral loss-of-heterozygosity mutations at a genome-wide level, including previously unreported changes such as homozygosity for DNMT3A R882 mutations. Karyogene represents a dependable genomic diagnosis platform for translational research and for the clinical management of myeloid malignancies, which can be readily adapted for use in other cancers.
Assuntos
Genômica/métodos , Neoplasias Hematológicas , Leucemia Mieloide , Síndromes Mielodisplásicas , Proteínas de Transporte/genética , DNA (Citosina-5-)-Metiltransferases/genética , DNA Metiltransferase 3A , Feminino , Forminas , Neoplasias Hematológicas/diagnóstico , Neoplasias Hematológicas/genética , Histona-Lisina N-Metiltransferase/genética , Humanos , Leucemia Mieloide/diagnóstico , Leucemia Mieloide/genética , Masculino , Mutação , Síndromes Mielodisplásicas/diagnóstico , Síndromes Mielodisplásicas/genética , Proteína de Leucina Linfoide-Mieloide/genética , Proteínas de Fusão Oncogênica/genética , Tirosina Quinase 3 Semelhante a fms/genéticaRESUMO
Recurrent chromosomal translocations involving the mixed lineage leukaemia (MLL) gene initiate aggressive forms of leukaemia, which are often refractory to conventional therapies. Many MLL-fusion partners are members of the super elongation complex (SEC), a critical regulator of transcriptional elongation, suggesting that aberrant control of this process has an important role in leukaemia induction. Here we use a global proteomic strategy to demonstrate that MLL fusions, as part of SEC and the polymerase-associated factor complex (PAFc), are associated with the BET family of acetyl-lysine recognizing, chromatin 'adaptor' proteins. These data provided the basis for therapeutic intervention in MLL-fusion leukaemia, via the displacement of the BET family of proteins from chromatin. We show that a novel small molecule inhibitor of the BET family, GSK1210151A (I-BET151), has profound efficacy against human and murine MLL-fusion leukaemic cell lines, through the induction of early cell cycle arrest and apoptosis. I-BET151 treatment in two human leukaemia cell lines with different MLL fusions alters the expression of a common set of genes whose function may account for these phenotypic changes. The mode of action of I-BET151 is, at least in part, due to the inhibition of transcription at key genes (BCL2, C-MYC and CDK6) through the displacement of BRD3/4, PAFc and SEC components from chromatin. In vivo studies indicate that I-BET151 has significant therapeutic value, providing survival benefit in two distinct mouse models of murine MLL-AF9 and human MLL-AF4 leukaemia. Finally, the efficacy of I-BET151 against human leukaemia stem cells is demonstrated, providing further evidence of its potent therapeutic potential. These findings establish the displacement of BET proteins from chromatin as a promising epigenetic therapy for these aggressive leukaemias.