RESUMEN
Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal human malignancies, owing in part to its propensity for metastasis. Here, we used an organoid culture system to investigate how transcription and the enhancer landscape become altered during discrete stages of disease progression in a PDA mouse model. This approach revealed that the metastatic transition is accompanied by massive and recurrent alterations in enhancer activity. We implicate the pioneer factor FOXA1 as a driver of enhancer activation in this system, a mechanism that renders PDA cells more invasive and less anchorage-dependent for growth in vitro, as well as more metastatic in vivo. In this context, FOXA1-dependent enhancer reprogramming activates a transcriptional program of embryonic foregut endoderm. Collectively, our study implicates enhancer reprogramming, FOXA1 upregulation, and a retrograde developmental transition in PDA metastasis.
Asunto(s)
Adenocarcinoma/genética , Carcinoma Ductal Pancreático/genética , Elementos de Facilitación Genéticos , Regulación Neoplásica de la Expresión Génica , Factor Nuclear 3-alfa del Hepatocito/genética , Neoplasias Pancreáticas/genética , Adenocarcinoma/metabolismo , Adenocarcinoma/patología , Animales , Carcinoma Ductal Pancreático/metabolismo , Carcinoma Ductal Pancreático/patología , Línea Celular Tumoral , Modelos Animales de Enfermedad , Epigenómica , Femenino , Perfilación de la Expresión Génica , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Metástasis de la Neoplasia , Organoides/metabolismo , Páncreas/metabolismo , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologíaRESUMEN
Inhibition of the tumour suppressive function of p53 (encoded by TP53) is paramount for cancer development in humans. However, p53 remains unmutated in the majority of cases of glioblastoma (GBM)-the most common and deadly adult brain malignancy1,2. Thus, how p53-mediated tumour suppression is countered in TP53 wild-type (TP53WT) GBM is unknown. Here we describe a GBM-specific epigenetic mechanism in which the chromatin regulator bromodomain-containing protein 8 (BRD8) maintains H2AZ occupancy at p53 target loci through the EP400 histone acetyltransferase complex. This mechanism causes a repressive chromatin state that prevents transactivation by p53 and sustains proliferation. Notably, targeting the bromodomain of BRD8 displaces H2AZ, enhances chromatin accessibility and engages p53 transactivation. This in turn enforces cell cycle arrest and tumour suppression in TP53WT GBM. In line with these findings, BRD8 is highly expressed with H2AZ in proliferating single cells of patient-derived GBM, and is inversely correlated with CDKN1A, a canonical p53 target that encodes p21 (refs. 3,4). This work identifies BRD8 as a selective epigenetic vulnerability for a malignancy for which treatment has not improved for decades. Moreover, targeting the bromodomain of BRD8 may be a promising therapeutic strategy for patients with TP53WT GBM.
Asunto(s)
Epigénesis Genética , Glioblastoma , Factores de Transcripción , Proteína p53 Supresora de Tumor , Adulto , Humanos , Puntos de Control del Ciclo Celular , Línea Celular Tumoral , Cromatina/genética , Cromatina/metabolismo , Glioblastoma/genética , Glioblastoma/metabolismo , Glioblastoma/patología , Histonas/metabolismo , Factores de Transcripción/metabolismo , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Proliferación CelularRESUMEN
The lineage-specific transcription factor (TF) MEF2C is often deregulated in leukemia. However, strategies to target this TF have yet to be identified. Here, we used a domain-focused CRISPR screen to reveal an essential role for LKB1 and its Salt-Inducible Kinase effectors (SIK3, in a partially redundant manner with SIK2) to maintain MEF2C function in acute myeloid leukemia (AML). A key phosphorylation substrate of SIK3 in this context is HDAC4, a repressive cofactor of MEF2C. Consequently, targeting of LKB1 or SIK3 diminishes histone acetylation at MEF2C-bound enhancers and deprives leukemia cells of the output of this essential TF. We also found that MEF2C-dependent leukemias are sensitive to on-target chemical inhibition of SIK activity. This study reveals a chemical strategy to block MEF2C function in AML, highlighting how an oncogenic TF can be disabled by targeting of upstream kinases.
Asunto(s)
Leucemia Mieloide Aguda/enzimología , Proteínas Quinasas/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Quinasas de la Proteína-Quinasa Activada por el AMP , Acetilación , Animales , Antineoplásicos/farmacología , Proliferación Celular , Elementos de Facilitación Genéticos , Regulación Enzimológica de la Expresión Génica , Regulación Leucémica de la Expresión Génica , Células HEK293 , Células Hep G2 , Histona Desacetilasas/genética , Histona Desacetilasas/metabolismo , Histonas/metabolismo , Humanos , Células K562 , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patología , Factores de Transcripción MEF2/genética , Factores de Transcripción MEF2/metabolismo , Ratones , Células 3T3 NIH , Fosforilación , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Quinasas/genética , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/genética , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Transducción de Señal , Células THP-1 , Células U937RESUMEN
Small cell lung cancer (SCLC) is widely considered to be a tumor of pulmonary neuroendocrine cells; however, a variant form of this disease has been described that lacks neuroendocrine features. Here, we applied domain-focused CRISPR screening to human cancer cell lines to identify the transcription factor (TF) POU2F3 (POU class 2 homeobox 3; also known as SKN-1a/OCT-11) as a powerful dependency in a subset of SCLC lines. An analysis of human SCLC specimens revealed that POU2F3 is expressed exclusively in variant SCLC tumors that lack expression of neuroendocrine markers and instead express markers of a chemosensory lineage known as tuft cells. Using chromatin- and RNA-profiling experiments, we provide evidence that POU2F3 is a master regulator of tuft cell identity in a variant form of SCLC. Moreover, we show that most SCLC tumors can be classified into one of three lineages based on the expression of POU2F3, ASCL1, or NEUROD1. Our CRISPR screens exposed other unique dependencies in POU2F3-expressing SCLC lines, including the lineage TFs SOX9 and ASCL2 and the receptor tyrosine kinase IGF1R (insulin-like growth factor 1 receptor). These data reveal POU2F3 as a cell identity determinant and a dependency in a tuft cell-like variant of SCLC, which may reflect a previously unrecognized cell of origin or a trans-differentiation event in this disease.
Asunto(s)
Regulación Neoplásica de la Expresión Génica , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/fisiopatología , Factores de Transcripción de Octámeros/genética , Factores de Transcripción de Octámeros/metabolismo , Carcinoma Pulmonar de Células Pequeñas/genética , Carcinoma Pulmonar de Células Pequeñas/fisiopatología , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Diferenciación Celular , Línea Celular Tumoral , Linaje de la Célula , Humanos , Pulmón/patología , Ratones , Receptor IGF Tipo 1/metabolismoRESUMEN
Lineage plasticity is a prominent feature of pancreatic ductal adenocarcinoma (PDA) cells, which can occur via deregulation of lineage-specifying transcription factors. Here, we show that the zinc finger protein ZBED2 is aberrantly expressed in PDA and alters tumor cell identity in this disease. Unexpectedly, our epigenomic experiments reveal that ZBED2 is a sequence-specific transcriptional repressor of IFN-stimulated genes, which occurs through antagonism of IFN regulatory factor 1 (IRF1)-mediated transcriptional activation at cooccupied promoter elements. Consequently, ZBED2 attenuates the transcriptional output and growth arrest phenotypes downstream of IFN signaling in multiple PDA cell line models. We also found that ZBED2 is preferentially expressed in the squamous molecular subtype of human PDA, in association with inferior patient survival outcomes. Consistent with this observation, we show that ZBED2 can repress the pancreatic progenitor transcriptional program, enhance motility, and promote invasion in PDA cells. Collectively, our findings suggest that high ZBED2 expression is acquired during PDA progression to suppress the IFN response pathway and to promote lineage plasticity in this disease.
Asunto(s)
Carcinoma Ductal Pancreático/patología , Proteínas de Unión al ADN/metabolismo , Factor 1 Regulador del Interferón/metabolismo , Neoplasias Pancreáticas/patología , Factores de Transcripción/metabolismo , Animales , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/metabolismo , Carcinoma Ductal Pancreático/mortalidad , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Inmunoprecipitación de Cromatina , Proteínas de Unión al ADN/genética , Regulación Neoplásica de la Expresión Génica , Humanos , Factor 1 Regulador del Interferón/genética , Interferón gamma/farmacología , Ratones , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/mortalidad , Regiones Promotoras Genéticas , Análisis de Supervivencia , Factores de Transcripción/genéticaRESUMEN
Small cell lung cancers (SCLC) are comprised of heterogeneous subtypes marked by lineage-specific transcription factors, including ASCL1, NEUROD1, and POU2F3. POU2F3-positive SCLC, â¼12% of all cases, are uniquely dependent on POU2F3 itself; as such, approaches to attenuate POU2F3 expression may represent new therapeutic opportunities. Here using genome-scale screens for regulators of POU2F3 expression and SCLC proliferation, we define mSWI/SNF complexes, including non-canonical BAF (ncBAF) complexes, as top dependencies specific to POU2F3-positive SCLC. Notably, clinical-grade pharmacologic mSWI/SNF inhibition attenuates proliferation of all POU2F3-positive SCLCs, while disruption of ncBAF via BRD9 degradation is uniquely effective in pure non-neuroendocrine POU2F3-SCLCs. mSWI/SNF maintains accessibility over gene loci central to POU2F3-mediated gene regulatory networks. Finally, chemical targeting of SMARCA4/2 mSWI/SNF ATPases and BRD9 decrease POU2F3-SCLC tumor growth and increase survival in vivo . Taken together, these results characterize mSWI/SNF-mediated global governance of the POU2F3 oncogenic program and suggest mSWI/SNF inhibition as a therapeutic strategy for SCLC.
RESUMEN
Small cell lung cancers (SCLCs) are composed of heterogeneous subtypes marked by lineage-specific transcription factors, including ASCL1, NEUROD1, and POU2F3. POU2F3-positive SCLCs, â¼12% of all cases, are uniquely dependent on POU2F3 itself; as such, approaches to attenuate POU2F3 expression may represent new therapeutic opportunities. Here using genome-scale screens for regulators of POU2F3 expression and SCLC proliferation, we define mSWI/SNF complexes as top dependencies specific to POU2F3-positive SCLC. Notably, chemical disruption of mSWI/SNF ATPase activity attenuates proliferation of all POU2F3-positive SCLCs, while disruption of non-canonical BAF (ncBAF) via BRD9 degradation is effective in pure non-neuroendocrine POU2F3-SCLCs. mSWI/SNF targets to and maintains accessibility over gene loci central to POU2F3-mediated gene regulatory networks. Finally, clinical-grade pharmacologic disruption of SMARCA4/2 ATPases and BRD9 decreases POU2F3-SCLC tumor growth and increases survival in vivo. These results demonstrate mSWI/SNF-mediated governance of the POU2F3 oncogenic program and suggest mSWI/SNF inhibition as a therapeutic strategy for POU2F3-positive SCLCs.
Asunto(s)
Regulación Neoplásica de la Expresión Génica , Neoplasias Pulmonares , Carcinoma Pulmonar de Células Pequeñas , Factores de Transcripción , Humanos , Carcinoma Pulmonar de Células Pequeñas/genética , Carcinoma Pulmonar de Células Pequeñas/metabolismo , Carcinoma Pulmonar de Células Pequeñas/patología , Carcinoma Pulmonar de Células Pequeñas/tratamiento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patología , Neoplasias Pulmonares/tratamiento farmacológico , Animales , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Ratones , Línea Celular Tumoral , Proliferación Celular , Proteínas Cromosómicas no Histona/metabolismo , Proteínas Cromosómicas no Histona/genética , Factor 3 de Transcripción de Unión a Octámeros/metabolismo , Factor 3 de Transcripción de Unión a Octámeros/genéticaRESUMEN
During the progression of pancreatic ductal adenocarcinoma (PDAC), tumor cells are known to acquire transcriptional and morphological properties of the basal (also known as squamous) epithelial lineage, which leads to more aggressive disease characteristics. Here, we show that a subset of basal-like PDAC tumors aberrantly express p73 (TA isoform), which is a known transcriptional activator of basal lineage identity, ciliogenesis, and tumor suppression in normal tissue development. Using gain- and loss- of function experiments, we show that p73 is necessary and sufficient to activate genes related to basal identity (e.g. KRT5), ciliogenesis (e.g. FOXJ1), and p53-like tumor suppression (e.g. CDKN1A) in human PDAC models. Owing to the paradoxical combination of oncogenic and tumor suppressive outputs of this transcription factor, we propose that PDAC cells express a low level of p73 that is optimal for promoting lineage plasticity without severe impairment of cell proliferation. Collectively, our study reinforces how PDAC cells exploit master regulators of the basal epithelial lineage during disease progression.
RESUMEN
Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis, and new therapies are needed. Altered metabolism is a cancer vulnerability, and several metabolic pathways have been shown to promote PDAC. However, the changes in cholesterol metabolism and their role during PDAC progression remain largely unknown. Here we used organoid and mouse models to determine the drivers of altered cholesterol metabolism in PDAC and the consequences of its disruption on tumor progression. We identified sterol O-acyltransferase 1 (SOAT1) as a key player in sustaining the mevalonate pathway by converting cholesterol to inert cholesterol esters, thereby preventing the negative feedback elicited by unesterified cholesterol. Genetic targeting of Soat1 impairs cell proliferation in vitro and tumor progression in vivo and reveals a mevalonate pathway dependency in p53 mutant PDAC cells that have undergone p53 loss of heterozygosity (LOH). In contrast, pancreatic organoids lacking p53 mutation and p53 LOH are insensitive to SOAT1 loss, indicating a potential therapeutic window for inhibiting SOAT1 in PDAC.
Asunto(s)
Ácido Mevalónico/metabolismo , Neoplasias Pancreáticas/enzimología , Esterol O-Aciltransferasa/metabolismo , Animales , Línea Celular Tumoral , Colesterol/metabolismo , Progresión de la Enfermedad , Humanos , Pérdida de Heterocigocidad/genética , Ratones Endogámicos C57BL , Modelos Biológicos , Neoplasias Pancreáticas/patología , Esterol O-Aciltransferasa/deficiencia , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Pancreatic ductal adenocarcinoma (PDAC) is the most lethal common malignancy, with little improvement in patient outcomes over the past decades. Recently, subtypes of pancreatic cancer with different prognoses have been elaborated; however, the inability to model these subtypes has precluded mechanistic investigation of their origins. Here, we present a xenotransplantation model of PDAC in which neoplasms originate from patient-derived organoids injected directly into murine pancreatic ducts. Our model enables distinction of the two main PDAC subtypes: intraepithelial neoplasms from this model progress in an indolent or invasive manner representing the classical or basal-like subtypes of PDAC, respectively. Parameters that influence PDAC subtype specification in this intraductal model include cell plasticity and hyperactivation of the RAS pathway. Finally, through intratumoral dissection and the direct manipulation of RAS gene dosage, we identify a suite of RAS-regulated secreted and membrane-bound proteins that may represent potential candidates for therapeutic intervention in patients with PDAC. SIGNIFICANCE: Accurate modeling of the molecular subtypes of pancreatic cancer is crucial to facilitate the generation of effective therapies. We report the development of an intraductal organoid transplantation model of pancreatic cancer that models the progressive switching of subtypes, and identify stochastic and RAS-driven mechanisms that determine subtype specification.See related commentary by Pickering and Morton, p. 1448.This article is highlighted in the In This Issue feature, p. 1426.
Asunto(s)
Adenocarcinoma/genética , Regulación Neoplásica de la Expresión Génica/genética , Conductos Pancreáticos/trasplante , Animales , Carcinoma Ductal Pancreático , Modelos Animales de Enfermedad , Humanos , Ratones , PronósticoRESUMEN
The aberrant expression of squamous lineage markers in pancreatic ductal adenocarcinoma (PDA) has been correlated with poor clinical outcomes. However, the functional role of this putative transdifferentiation event in PDA pathogenesis remains unclear. Here, we show that expression of the transcription factor TP63 (ΔNp63) is sufficient to install and sustain the enhancer landscape and transcriptional signature of the squamous lineage in human PDA cells. We also demonstrate that TP63-driven enhancer reprogramming promotes aggressive tumor phenotypes, including enhanced cell motility and invasion, and an accelerated growth of primary PDA tumors and metastases in vivo. This process ultimately leads to a powerful addiction of squamous PDA cells to continuous TP63 expression. Our study demonstrates the functional significance of squamous transdifferentiation in PDA and reveals TP63-based reprogramming as an experimental tool for investigating mechanisms and vulnerabilities linked to this aberrant cell fate transition.
Asunto(s)
Carcinoma Ductal Pancreático/genética , Carcinoma de Células Escamosas/genética , Elementos de Facilitación Genéticos , Factores de Transcripción/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Animales , Carcinogénesis/genética , Carcinoma Ductal Pancreático/patología , Carcinoma de Células Escamosas/patología , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Genoma Humano , Humanos , Ratones , Fenotipo , Transcripción GenéticaRESUMEN
Targeting of general coactivators is an emerging strategy to interfere with oncogenic transcription factors (TFs). However, coactivator perturbations often lead to pleiotropic effects by influencing numerous TFs. Here we identify TAF12, a subunit of TFIID and SAGA coactivator complexes, as a selective requirement for acute myeloid leukemia (AML) progression. We trace this dependency to a direct interaction between the TAF12/TAF4 histone-fold heterodimer and the transactivation domain of MYB, a TF with established roles in leukemogenesis. Ectopic expression of the TAF4 histone-fold fragment can efficiently squelch TAF12 in cells, suppress MYB, and regress AML in mice. Our study reveals a strategy for potent MYB inhibition in AML and highlights how an oncogenic TF can be selectively neutralized by targeting a general coactivator complex.
Asunto(s)
Leucemia Mieloide Aguda/metabolismo , Factores Asociados con la Proteína de Unión a TATA/metabolismo , Factor de Transcripción TFIID/metabolismo , Animales , Humanos , Ratones Transgénicos , OncogenesRESUMEN
The Iroquois homeodomain transcription factor gene IRX3 is expressed in the developing nervous system, limb buds, and heart, and transcript levels specify obesity risk in humans. We now report a functional role for IRX3 in human acute leukemia. Although transcript levels are very low in normal human bone marrow cells, high IRX3 expression is found in â¼30% of patients with acute myeloid leukemia (AML), â¼50% with T-acute lymphoblastic leukemia, and â¼20% with B-acute lymphoblastic leukemia, frequently in association with high-level HOXA gene expression. Expression of IRX3 alone was sufficient to immortalize hematopoietic stem and progenitor cells (HSPCs) in myeloid culture and induce lymphoid leukemias in vivo. IRX3 knockdown induced terminal differentiation of AML cells. Combined IRX3 and Hoxa9 expression in murine HSPCs impeded normal T-progenitor differentiation in lymphoid culture and substantially enhanced the morphologic and phenotypic differentiation block of AML in myeloid leukemia transplantation experiments through suppression of a terminal myelomonocytic program. Likewise, in cases of primary human AML, high IRX3 expression is strongly associated with reduced myelomonocytic differentiation. Thus, tissue-inappropriate derepression of IRX3 contributes significantly to the block in differentiation, which is the pathognomonic feature of human acute leukemias.
Asunto(s)
Proteínas de Homeodominio/genética , Leucemia Mieloide Aguda/genética , Factores de Transcripción/genética , Animales , Diferenciación Celular , Humanos , Leucemia Mieloide Aguda/patología , RatonesRESUMEN
The Mixed Lineage Leukemia gene (MLL) is altered in leukemia by chromosomal translocations to produce oncoproteins composed of the MLL N-terminus fused to the C-terminus of a partner protein. Here, we used domain-focused CRISPR screening to identify ZFP64 as an essential transcription factor in MLL-rearranged leukemia. We show that the critical function of ZFP64 in leukemia is to maintain MLL expression via binding to the MLL promoter, which is the most enriched location of ZFP64 occupancy in the human genome. The specificity of ZFP64 for MLL is accounted for by an exceptional density of ZFP64 motifs embedded within the MLL promoter. These findings demonstrate how a sequence anomaly of an oncogene promoter can impose a transcriptional addiction in cancer.
Asunto(s)
Proteínas de Unión al ADN/genética , Leucemia Bifenotípica Aguda/genética , Proteína de la Leucemia Mieloide-Linfoide/genética , Regiones Promotoras Genéticas/genética , Factores de Transcripción/genética , Translocación Genética , Células A549 , Animales , Línea Celular Tumoral , Proteínas de Unión al ADN/metabolismo , Regulación Leucémica de la Expresión Génica , Células HEK293 , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Células K562 , Leucemia Bifenotípica Aguda/metabolismo , Leucemia Bifenotípica Aguda/patología , Ratones Endogámicos NOD , Ratones Noqueados , Ratones SCID , Proteína de la Leucemia Mieloide-Linfoide/metabolismo , Proteínas de Fusión Oncogénica/genética , Proteínas de Fusión Oncogénica/metabolismo , Células THP-1 , Factores de Transcripción/metabolismo , Trasplante HeterólogoRESUMEN
Pancreatic cancer is the most lethal common solid malignancy. Systemic therapies are often ineffective, and predictive biomarkers to guide treatment are urgently needed. We generated a pancreatic cancer patient-derived organoid (PDO) library that recapitulates the mutational spectrum and transcriptional subtypes of primary pancreatic cancer. New driver oncogenes were nominated and transcriptomic analyses revealed unique clusters. PDOs exhibited heterogeneous responses to standard-of-care chemotherapeutics and investigational agents. In a case study manner, we found that PDO therapeutic profiles paralleled patient outcomes and that PDOs enabled longitudinal assessment of chemosensitivity and evaluation of synchronous metastases. We derived organoid-based gene expression signatures of chemosensitivity that predicted improved responses for many patients to chemotherapy in both the adjuvant and advanced disease settings. Finally, we nominated alternative treatment strategies for chemorefractory PDOs using targeted agent therapeutic profiling. We propose that combined molecular and therapeutic profiling of PDOs may predict clinical response and enable prospective therapeutic selection.Significance: New approaches to prioritize treatment strategies are urgently needed to improve survival and quality of life for patients with pancreatic cancer. Combined genomic, transcriptomic, and therapeutic profiling of PDOs can identify molecular and functional subtypes of pancreatic cancer, predict therapeutic responses, and facilitate precision medicine for patients with pancreatic cancer. Cancer Discov; 8(9); 1112-29. ©2018 AACR.See related commentary by Collisson, p. 1062This article is highlighted in the In This Issue feature, p. 1047.
Asunto(s)
Antineoplásicos/farmacología , Perfilación de la Expresión Génica/métodos , Redes Reguladoras de Genes/efectos de los fármacos , Organoides/efectos de los fármacos , Neoplasias Pancreáticas/patología , Antineoplásicos/uso terapéutico , Resistencia a Antineoplásicos/efectos de los fármacos , Ensayos de Selección de Medicamentos Antitumorales , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Terapia Molecular Dirigida , Organoides/química , Organoides/citología , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/genética , Medicina de Precisión , Estudios Prospectivos , Análisis de Secuencia de ARN , Nivel de Atención , Células Tumorales CultivadasRESUMEN
Tissue-inappropriate derepression of the mesenchymal transcription factor gene Forkhead Box C1 (FOXC1) occurs in approximately 20% of patients with acute myeloid leukemia. Through experimental and bioinformatics analyses, we have demonstrated this to be both functional (enhancing the myeloid lineage differentiation block characteristic of the disease) and adversely prognostic.
RESUMEN
In this issue of Cancer Cell, Lu et al. use a mouse model of DNMT3A(R882H)/NRAS(G12D) acute myeloid leukemia to define a cascade of chromatin changes that emanate from DNMT3A-bound enhancers to initiate disease. The authors also reveal a chemical strategy to interrupt this process.
Asunto(s)
ADN (Citosina-5-)-Metiltransferasas/genética , Leucemia Mieloide Aguda , Animales , Epigenómica , MutaciónRESUMEN
Given the importance of deregulated phosphoinositide (PI) signaling in leukemic hematopoiesis, genes coding for proteins that regulate PI metabolism may have significant and as yet unappreciated roles in leukemia. We performed a targeted knockdown (KD) screen of PI modulator genes in human acute myeloid leukemia (AML) cells and identified candidates required to sustain proliferation or prevent apoptosis. One of these, the lipid kinase phosphatidylinositol-5-phosphate 4-kinase, type II, alpha (PIP4K2A) regulates cellular levels of phosphatidylinositol-5-phosphate (PtsIns5P) and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). We found PIP4K2A to be essential for the clonogenic and leukemia-initiating potential of human AML cells, and for the clonogenic potential of murine MLL-AF9 AML cells. Importantly, PIP4K2A is also required for the clonogenic potential of primary human AML cells. Its KD results in accumulation of the cyclin-dependent kinase inhibitors CDKN1A and CDKN1B, G1 cell cycle arrest and apoptosis. Both CDKN1A accumulation and apoptosis were partially dependent on activation of the mTOR pathway. Critically, however, PIP4K2A KD in normal hematopoietic stem and progenitor cells, both murine and human, did not adversely impact either clonogenic or multilineage differentiation potential, indicating a selective dependency that we suggest may be the consequence of the regulation of different transcriptional programs in normal versus malignant cells. Thus, PIP4K2A is a novel candidate therapeutic target in myeloid malignancy.
Asunto(s)
Técnicas de Silenciamiento del Gen , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Fosfatidilinositoles/metabolismo , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Animales , Apoptosis , Línea Celular Tumoral , Proliferación Celular , Supervivencia Celular/genética , Análisis por Conglomerados , Activación Enzimática , Perfilación de la Expresión Génica , Humanos , Espacio Intracelular/metabolismo , Leucemia Mieloide Aguda/patología , Ratones , Ratones Transgénicos , Células Madre Neoplásicas/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Ensayo de Tumor de Célula MadreRESUMEN
Through in silico and other analyses, we identified FOXC1 as expressed in at least 20% of human AML cases, but not in normal hematopoietic populations. FOXC1 expression in AML was almost exclusively associated with expression of the HOXA/B locus. Functional experiments demonstrated that FOXC1 contributes to a block in monocyte/macrophage differentiation and enhances clonogenic potential. In in vivo analyses, FOXC1 collaborates with HOXA9 to accelerate significantly the onset of symptomatic leukemia. A FOXC1-repressed gene set identified in murine leukemia exhibited quantitative repression in human AML in accordance with FOXC1 expression, and FOXC1(high) human AML cases exhibited reduced morphologic monocytic differentiation and inferior survival. Thus, FOXC1 is frequently derepressed to functional effect in human AML.