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1.
Br J Haematol ; 201(4): 718-724, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36786170

RESUMO

Despite the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway being frequently altered in T-ALL/LBL, no specific therapy has been approved for T-ALL/LBL patients with constitutive signalling by JAK/STAT, so there is an urgent need to identify pathway members that may be potential therapeutic targets. In the present study, we searched for JAK/STAT pathway members potentially modulated through aberrant methylation and identified SOCS3 hypermethylation as a recurrent event in T-ALL/LBL. Additionally, we explored the implications of SOCS3 deregulation in T-ALL/LBL and demonstrated that SOCS3 counteracts the constitutive activation of the JAK/STAT pathway through different molecular mechanisms. Therefore, SOCS3 emerges as a potential therapeutic target in T-ALL/LBL.


Assuntos
Leucemia-Linfoma de Células T do Adulto , Leucemia-Linfoma Linfoblástico de Células T Precursoras , Humanos , Janus Quinases/metabolismo , Transdução de Sinais , Proteína 3 Supressora da Sinalização de Citocinas/genética , Proteína 3 Supressora da Sinalização de Citocinas/metabolismo , Fatores de Transcrição STAT/metabolismo , Fator de Transcrição STAT3/metabolismo , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Linfócitos T/metabolismo
2.
Int J Mol Sci ; 24(12)2023 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-37373496

RESUMO

The standard-of-care treatment of T-cell acute lymphoblastic leukaemia (T-ALL) with chemotherapy usually achieves reasonable rates of initial complete response. However, patients who relapse or do not respond to conventional therapy show dismal outcomes, with cure rates below 10% and limited therapeutic options. To ameliorate the clinical management of these patients, it is urgent to identify biomarkers able to predict their outcomes. In this work, we investigate whether NRF2 activation constitutes a biomarker with prognostic value in T-ALL. Using transcriptomic, genomic, and clinical data, we found that T-ALL patients with high NFE2L2 levels had shorter overall survival. Our results demonstrate that the PI3K-AKT-mTOR pathway is involved in the oncogenic signalling induced by NRF2 in T-ALL. Furthermore, T-ALL patients with high NFE2L2 levels displayed genetic programs of drug resistance that may be provided by NRF2-induced biosynthesis of glutathione. Altogether, our results indicate that high levels of NFE2L2 may be a predictive biomarker of poor treatment response in T-ALL patients, which would explain the poor prognosis associated with these patients. This enhanced understanding of NRF2 biology in T-ALL may allow a more refined stratification of patients and the proposal of targeted therapies, with the ultimate goal of improving the outcome of relapsed/refractory T-ALL patients.


Assuntos
Leucemia-Linfoma Linfoblástico de Células T Precursoras , Humanos , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Fator 2 Relacionado a NF-E2/genética , Prognóstico , Fosfatidilinositol 3-Quinases , Recidiva Local de Neoplasia , Linfócitos T
3.
Oncologist ; 26(2): e298-e305, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33191568

RESUMO

The NOTCH1 gene encodes a transmembrane receptor protein with activating mutations observed in many T-cell acute lymphoblastic leukemias (T-ALLs) and lymphomas, as well as in other tumor types, which has led to interest in inhibiting NOTCH1 signaling as a therapeutic target in cancer. Several classes of Notch inhibitors have been developed, including monoclonal antibodies against NOTCH receptors or ligands, decoys, blocking peptides, and γ-secretase inhibitors (GSIs). GSIs block a critical proteolytic step in NOTCH activation and are the most widely studied. Current treatments with GSIs have not successfully passed clinical trials because of side effects that limit the maximum tolerable dose. Multiple γ-secretase-cleavage substrates may be involved in carcinogenesis, indicating that there may be other targets for GSIs. Resistance mechanisms may include PTEN inactivation, mutations involving FBXW7, or constitutive MYC expression conferring independence from NOTCH1 inactivation. Recent studies have suggested that selective targeting γ-secretase may offer an improved efficacy and toxicity profile over the effects caused by broad-spectrum GSIs. Understanding the mechanism of GSI-induced cell death and the ability to accurately identify patients based on the activity of the pathway will improve the response to GSI and support further investigation of such compounds for the rational design of anti-NOTCH1 therapies for the treatment of T-ALL. IMPLICATIONS FOR PRACTICE: γ-secretase has been proposed as a therapeutic target in numerous human conditions, including cancer. A better understanding of the structure and function of the γ-secretase inhibitor (GSI) would help to develop safe and effective γ-secretase-based therapies. The ability to accurately identify patients based on the activity of the pathway could improve the response to GSI therapy for the treatment of cancer. Toward these ends, this study focused on γ-secretase inhibitors as a potential therapeutic target for the design of anti-NOTCH1 therapies for the treatment of T-cell acute lymphoblastic leukemias and lymphomas.


Assuntos
Secretases da Proteína Precursora do Amiloide , Leucemia-Linfoma Linfoblástico de Células T Precursoras , Secretases da Proteína Precursora do Amiloide/metabolismo , Linhagem Celular Tumoral , Humanos , Mutação , Receptor Notch1/genética , Receptores Notch/genética , Transdução de Sinais
4.
Carcinogenesis ; 41(8): 1113-1122, 2020 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-31734690

RESUMO

Precursor T-cell lymphoblastic neoplasms are aggressive malignancies in need for more effective and specific therapeutic treatments. A significant fraction of these neoplasms harbor deletions on the locus 9p21, targeting the tumor suppressor CDKN2A but also deleting the aconitase 1 (ACO1) gene, a neighboring housekeeping gene involved in cytoplasm and mitochondrial metabolism. Here we show that reducing the aconitase activity with fluorocitrate decreases the viability of T-cell lymphoblastic neoplasia cells in correlation to the differential aconitase expression. The consequences of the treatment were evidenced in vitro using T-cell lymphoblastic neoplasia cell lines exhibiting 9p21 deletions and variable levels of ACO1 expression or activity. Similar results were observed in melanoma cell lines, suggesting a true potential for fluorocitrate in different cancer types. Notably, ectopic expression of ACO1 alleviated the susceptibility of cell lines to fluorocitrate and, conversely, knockdown experiments increased susceptibility of resistant cell lines. These findings were confirmed in vivo on athymic nude mice by using tumor xenografts derived from two T-cell lines with different levels of ACO1. Taken together, our results indicate that the non-targeted ACO1 deficiency induced by common deletions exerts a collateral cellular lethality that can be used as a novel therapeutic strategy in the treatment of several types of cancer.


Assuntos
Cromossomos Humanos Par 9/genética , Citratos/farmacologia , Resistencia a Medicamentos Antineoplásicos/genética , Inibidores Enzimáticos/farmacologia , Deleção de Genes , Proteína 1 Reguladora do Ferro/deficiência , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Citratos/uso terapêutico , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidores Enzimáticos/uso terapêutico , Feminino , Xenoenxertos , Humanos , Proteína 1 Reguladora do Ferro/antagonistas & inibidores , Proteína 1 Reguladora do Ferro/genética , Melanoma/genética , Camundongos , Camundongos Nus , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamento farmacológico , Neoplasias Cutâneas/genética
5.
BMC Cancer ; 19(1): 1005, 2019 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-31655559

RESUMO

BACKGROUND: Acute T-cell lymphoblastic leukaemia (T-ALL) is an aggressive disorder derived from immature thymocytes. The variability observed in clinical responses on this type of tumours to treatments, the high toxicity of current protocols and the poor prognosis of patients with relapse or refractory make it urgent to find less toxic and more effective therapies in the context of a personalized medicine of precision. METHODS: Whole exome sequencing and RNAseq were performed on DNA and RNA respectively, extracted of a bone marrow sample from a patient diagnosed with tumour primary T-ALL and double negative thymocytes from thymus control samples. We used PanDrugs, a computational resource to propose pharmacological therapies based on our experimental results, including lists of variants and genes. We extend the possible therapeutic options for the patient by taking into account multiple genomic events potentially sensitive to a treatment, the context of the pathway and the pharmacological evidence already known by large-scale experiments. RESULTS: As a proof-of-principle we used next-generation-sequencing technologies (Whole Exome Sequencing and RNA-Sequencing) in a case of diagnosed Pro-T acute lymphoblastic leukaemia. We identified 689 disease-causing mutations involving 308 genes, as well as multiple fusion transcript variants, alternative splicing, and 6652 genes with at least one principal isoform significantly deregulated. Only 12 genes, with 27 pathogenic gene variants, were among the most frequently mutated ones in this type of lymphoproliferative disorder. Among them, 5 variants detected in CTCF, FBXW7, JAK1, NOTCH1 and WT1 genes have not yet been reported in T-ALL pathogenesis. CONCLUSIONS: Personalized genomic medicine is a therapeutic approach involving the use of an individual's information data to tailor drug therapy. Implementing bioinformatics platform PanDrugs enables us to propose a prioritized list of anticancer drugs as the best theoretical therapeutic candidates to treat this patient has been the goal of this article. Of note, most of the proposed drugs are not being yet considered in the clinical practice of this type of cancer opening up the approach of new treatment possibilities.


Assuntos
Antineoplásicos/uso terapêutico , Genoma Humano/genética , Genômica/métodos , Medicina de Precisão/métodos , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamento farmacológico , Adolescente , Processamento Alternativo/genética , Exoma/genética , Fusão Gênica/genética , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Masculino , Mutação/genética , RNA-Seq , Espanha , Transcriptoma/genética
7.
BMC Cancer ; 18(1): 430, 2018 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-29661169

RESUMO

BACKGROUND: Precursor T-cell lymphoblastic lymphomas (T-LBL) are rare aggressive hematological malignancies that mainly develop in children. As in other cancers, the loss of cell cycle control plays a prominent role in the pathogenesis in these malignancies that is primarily attributed to loss of CDKN2A (encoding protein p16INK4A). However, the impact of the deregulation of other genes such as CDKN1C, E2F1, and TP53 remains to be clarified. Interestingly, experiments in mouse models have proven that conditional T-cell specific deletion of Cdkn1c gene may induce a differentiation block at the DN3 to DN4 transition, and that the loss of this gene in the absence of Tp53 led to aggressive thymic lymphomas. RESULTS: In this manuscript, we demonstrated that the simultaneous deregulation of CDKN1C, E2F1, and TP53 genes by epigenetic mechanisms and/or the deregulation of specific microRNAs, together with additional impairing of TP53 function by the expression of dominant-negative isoforms are common features in primary human T-LBLs. CONCLUSIONS: Previous experimental work in mice revealed that T-cell specific deletion of Cdkn1c accelerates lymphomagenesis in the absence of Tp53. If, as expected, the consequences of the deregulation of the CDKN1C-E2F1-TP53 axis were the same as those experimentally demonstrated in mouse models, the disruption of this axis might be useful to predict tumor aggressiveness, and to provide the basis towards the development of potential therapeutic strategiesin human T-LBL.


Assuntos
Inibidor de Quinase Dependente de Ciclina p57/genética , Fator de Transcrição E2F1/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Proteína Supressora de Tumor p53/genética , Adolescente , Adulto , Animais , Criança , Epigênese Genética/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Camundongos , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patologia , Análise de Sequência de RNA , Transdução de Sinais/genética , Adulto Jovem
8.
BMC Genomics ; 17: 698, 2016 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-27581076

RESUMO

BACKGROUND: Radio-Adaptive Response (RAR) is a biological defense mechanism whereby exposure to low dose ionizing radiation (IR) mitigates the detrimental effects of high dose irradiation. RAR has been widely observed in vivo using as endpoint less induction of apoptosis. However, sex differences associated with RAR and variations between males and females on global gene expression influenced by RAR have not been still investigated. In addition, the response to radiation-induced apoptosis is associated with phosphorylation of TRP53 at both the serine 15 (ser-18 in the mouse) and serine 392 (ser-389 in mice) residues, but the role of these two phosphorylated forms in male and female RAR remains to be elucidated. RESULTS: We analyzed the effect of administering priming low dose radiation (0.075 Gy of X-rays) prior to high dose radiation (1.75 Gy of γ-rays) on the level of caspase-3-mediated apoptosis and on global transcriptional expression in thymocytes of male and female mice. Here, we provide the first evidence of a differential sex effect of RAR on the reduction of thymocyte apoptosis with males showing lesser levels of caspase-3-mediated apoptosis than females. Analysis of transcriptomic profiles of 1944 genes involved in apoptosis signaling in radio-adapted thymocytes identified 17 transcripts exhibiting differential expression between both sexes. Among them, Dlc1 and Fis1 are closely related to the apoptosis mediated by the TRP53 protein. Our data demonstrate that overexpression of Dlc1 and Fis1 occur concomitantly with a highest accumulation of phosphoserine-18-TRP53 and caspase-3 in radio-adapted thymocytes of female mice. In an opposite way, both down-modulation of Fis1 and phosphoserine-389-TRP53 accumulation appear to be associated with protection from thymocyte apoptosis mediated by caspase-3 in males. CONCLUSIONS: Transcriptomic analysis performed in this work reveals for the first time sex-specific differences in gene expression influenced by RAR. Our results also suggest a sex-dependent dual role for phosphoserine-18-TRP53 and phosphoserine-389-TRP53 in the regulation of the radio-adaptive response in mouse thymocytes.


Assuntos
Caspase 3/metabolismo , Perfilação da Expressão Gênica/métodos , Lectinas Tipo C/genética , Proteínas de Membrana/genética , Proteínas Mitocondriais/genética , Timócitos/citologia , Proteína Supressora de Tumor p53/metabolismo , Adaptação Fisiológica/efeitos da radiação , Animais , Apoptose , Feminino , Regulação da Expressão Gênica/efeitos da radiação , Masculino , Camundongos , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Fosforilação , Caracteres Sexuais , Timócitos/metabolismo , Timócitos/efeitos da radiação
9.
Proc Natl Acad Sci U S A ; 107(31): 13736-41, 2010 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-20631301

RESUMO

The longevity-promoting NAD+-dependent class III histone deacetylase Sirtuin 1 (SIRT1) is involved in stem cell function by controlling cell fate decision and/or by regulating the p53-dependent expression of NANOG. We show that SIRT1 is down-regulated precisely during human embryonic stem cell differentiation at both mRNA and protein levels and that the decrease in Sirt1 mRNA is mediated by a molecular pathway that involves the RNA-binding protein HuR and the arginine methyltransferase coactivator-associated arginine methyltransferase 1 (CARM1). SIRT1 down-regulation leads to reactivation of key developmental genes such as the neuroretinal morphogenesis effectors DLL4, TBX3, and PAX6, which are epigenetically repressed by this histone deacetylase in pluripotent human embryonic stem cells. Our results indicate that SIRT1 is regulated during stem cell differentiation in the context of a yet-unknown epigenetic pathway that controls specific developmental genes in embryonic stem cells.


Assuntos
Diferenciação Celular , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Sirtuína 1/metabolismo , Animais , Proteínas Adaptadoras de Sinalização CARD/metabolismo , Linhagem Celular , Guanilato Ciclase/metabolismo , Humanos , Camundongos , Camundongos Knockout , Células-Tronco Pluripotentes/citologia , Células-Tronco Pluripotentes/metabolismo , Estabilidade de RNA , Sirtuína 1/deficiência , Sirtuína 1/genética
10.
Carcinogenesis ; 33(2): 452-8, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22114070

RESUMO

Cryptic deletions at chromosome 6q are common cytogenetic abnormalities in T-cell lymphoblastic leukemia/lymphoma (T-LBL), but the target genes have not been formally identified. Our results build on detection of specific chromosomal losses in a mouse model of γ-radiation-induced T-LBLs and provide interesting clues for new putative susceptibility genes in a region orthologous to human 6q15-6q16.3. Among these, Epha7 emerges as a bona fide candidate tumor suppressor gene because it is inactivated in practically all the T-LBLs analyzed (100% in mouse and 95.23% in human). We provide evidence showing that Epha7 downregulation may occur, at least in part, by loss of heterozygosity (19.35% in mouse and 12.5% in human) or promoter hypermethylation (51.61% in mouse and 43.75% in human) or a combination of both mechanisms (12.90% in mouse and 6.25% in human). These results indicate that EPHA7 might be considered a new tumor suppressor gene for 6q deletions in T-LBLs. Notably, this gene is located in 6q16.1 proximal to GRIK2 and CASP8AP2, other candidate genes identified in this region. Thus, del6q seems to be a complex region where inactivation of multiple genes may cooperatively contribute to the onset of T-cell lymphomas.


Assuntos
Leucemia de Células T/genética , Leucemia-Linfoma de Células T do Adulto/genética , Linfoma de Células T/genética , Receptor EphA7/genética , Deleção de Sequência , Animais , Proteínas de Ligação ao Cálcio/genética , Linhagem Celular Tumoral , Deleção Cromossômica , Cromossomos Humanos Par 4 , Cromossomos Humanos Par 6/genética , Metilação de DNA , Regulação para Baixo , Feminino , Genes Supressores de Tumor , Humanos , Células Jurkat , Perda de Heterozigosidade , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Regiões Promotoras Genéticas , Receptores de Ácido Caínico/genética , Receptor de GluK2 Cainato
11.
Noncoding RNA ; 8(2)2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-35447889

RESUMO

Circular RNAs (circRNAs) are suggested to play a discriminative role between some stages of thymocyte differentiation. However, differential aspects of the stage of mature single-positive thymocytes remain to be explored. The purpose of this study is to investigate the differential expression pattern of circRNAs in three different development stages of human thymocytes, including mature single-positive cells, and perform predictions in silico regarding the ability of specific circRNAs when controlling the expression of genes involved in thymocyte differentiation. We isolate human thymocytes at three different stages of intrathymic differentiation and determine the expression of circRNAs and mRNA by RNASeq. We show that the differential expression pattern of 50 specific circRNAs serves to discriminate between the three human thymocyte populations. Interestingly, the downregulation of RAG2, a gene involved in T-cell differentiation in the thymus, could be simultaneously controlled by the downregulation of two circRNASs (hsa_circ_0031584 and hsa_circ_0019079) through the hypothetical liberation of hsa-miR-609. Our study provides, for the first time, significant insights into the usefulness of circRNAs in discriminating between different stages of thymocyte differentiation and provides new potential circRNA-miRNA-mRNA networks capable of controlling the expression of genes involved in T-cell differentiation in the thymus.

12.
Sci Rep ; 12(1): 3144, 2022 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-35210498

RESUMO

In the quest for more effective radiation treatment options that can improve both cell killing and healthy tissue recovery, combined radiation therapies are lately in the spotlight. The molecular response to a combined radiation regime where exposure to an initial low dose (priming dose) of ionizing radiation is administered prior to a subsequent higher radiation dose (challenging dose) after a given latency period have not been thoroughly explored. In this study we report on the differential response to either a combined radiation regime or a single challenging dose both in mouse in vivo and in human ex vivo thymocytes. A differential cell cycle response including an increase in the subG1 fraction on cells exposed to the combined regime was found. Together with this, a differential protein expression profiling in several pathways including cell cycle control (ATM, TP53, p21CDKN1A), damage response (γH2AX) and cell death pathways such as apoptosis (Cleaved Caspase-3, PARP1, PKCδ and H3T45ph) and ferroptosis (xCT/GPX4) was demonstrated. This study also shows the epigenetic regulation following a combined regime that alters the expression of chromatin modifiers such as DNMTs (DNMT1, DNMT2, DNMT3A, DNMT3B, DNMT3L) and glycosylases (MBD4 and TDG). Furthermore, a study of the underlying cellular status six hours after the priming dose alone showed evidence of retained modifications on the molecular and epigenetic pathways suggesting that the priming dose infers a "radiation awareness phenotype" to the thymocytes, a sensitization key to the differential response seen after the second hit with the challenging dose. These data suggest that combined-dose radiation regimes could be more efficient at making cells respond to radiation and it would be interesting to further investigate how can these schemes be of use to potential new radiation therapies.


Assuntos
Ciclo Celular/efeitos da radiação , Dano ao DNA , Regulação da Expressão Gênica/efeitos da radiação , Timócitos/metabolismo , Raios X/efeitos adversos , Animais , Relação Dose-Resposta à Radiação , Feminino , Humanos , Camundongos
13.
Sci Rep ; 9(1): 5179, 2019 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-30914738

RESUMO

Fusions transcripts have been proven to be strong drivers for neoplasia-associated mutations, although their incidence in T-cell lymphoblastic lymphoma needs to be determined yet. Using RNA-Seq we have selected 55 fusion transcripts identified by at least two of three detection methods in the same tumour. We confirmed the existence of 24 predicted novel fusions that had not been described in cancer or normal tissues yet, indicating the accuracy of the prediction. Of note, one of them involves the proto oncogene TAL1. Other confirmed fusions could explain the overexpression of driver genes such as COMMD3-BMI1, LMO1 or JAK3. Five fusions found exclusively in tumour samples could be considered pathogenic (NFYG-TAL1, RIC3-TCRBC2, SLC35A3-HIAT1, PICALM MLLT10 and MLLT10-PICALM). However, other fusions detected simultaneously in normal and tumour samples (JAK3-INSL3, KANSL1-ARL17A/B and TFG-ADGRG7) could be germ-line fusions genes involved in tumour-maintaining tasks. Notably, some fusions were confirmed in more tumour samples than predicted, indicating that the detection methods underestimated the real number of existing fusions. Our results highlight the potential of RNA-Seq to identify new cryptic fusions, which could be drivers or tumour-maintaining passenger genes. Such novel findings shed light on the searching for new T-LBL biomarkers in these haematological disorders.


Assuntos
Proteínas de Fusão Oncogênica/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , RNA-Seq , Algoritmos , Sequência de Bases , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Humanos , Proteínas de Fusão Oncogênica/metabolismo , Proto-Oncogene Mas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
14.
Oncogene ; 38(23): 4620-4636, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30742097

RESUMO

FBXW7 is a driver gene in T-cell lymphoblastic neoplasia acting through proteasome degradation of key proto-oncogenes. FBXW7 encodes three isoforms, α, ß and γ, which differ only in the N-terminus. In this work, massive sequencing revealed significant downregulation of FBXW7 in a panel of primary T-cell lymphoblastic lymphomas characterised by the absence of mutations in its sequence. We observed that decreased expression mainly affected the FBXW7ß isoform and to a lesser extent FBXW7α and may be attributed to the combined effect of epigenetic changes, alteration of upstream factors and upregulation of miRNAs. Transient transfections with miRNA mimics in selected cell lines resulted in a significant decrease of total FBXW7 expression and its different isoforms separately, with the consequent increment of critical substrates and the stimulation of cell proliferation. Transient inhibition of endogenous miRNAs in a T-cell lymphoblastic-derived cell line (SUP-T1) was capable of reversing these proliferative effects. Finally, we show how FBXW7 isoforms display different roles within the cell. Simultaneous downregulation of the α and γ isoforms modulates the amount of CCNE1, whilst the ß-isoform alone was found to have a prominent role in modulating the amount of c-MYC. Our data also revealed that downregulation of all isoforms is a sine qua non condition to induce a proliferative pattern in our cell model system. Taking these data into account, potential new treatments to reverse downregulation of all or a specific FBXW7 isoform may be an effective strategy to counteract the proliferative capacity of these tumour cells.


Assuntos
Proteína 7 com Repetições F-Box-WD/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Linhagem Celular Tumoral , Regulação para Baixo/genética , Epigênese Genética , Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Regulação Leucêmica da Expressão Gênica , Humanos , Isoenzimas/genética , Células Jurkat , MicroRNAs/genética , Análise em Microsséries , Leucemia-Linfoma Linfoblástico de Células T Precursoras/enzimologia
15.
Epigenetics ; 5(7): 656-63, 2010 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-20716963

RESUMO

MicroRNAs (miRNAs) are short non-coding RNA molecules that regulate post-transcriptional gene expression. They influence a wide range of physiological functions, including neuronal processes, and are regulated by various mechanisms, such as DNA methylation. This epigenetic mark is recognized by transcriptional regulators such as the methyl CpG binding protein Mecp2. Rett syndrome is a complex neurological disorder that has been associated with mutations in the gene coding for Mecp2. Thus, we examined the possible miRNA misregulation caused by Mecp2 absence in a mouse model of Rett syndrome. Using miRNA expression microarrays, we observed that the brain of Rett syndrome mice undergoes a disruption of the expression profiles of miRNAs. Among the significantly altered miRNAs (26%, 65 of 245), overall downregulation of these transcripts was the most common feature (71%), whilst the remaining 30% were upregulated. Further validation by quantitative RT-PCR demonstrated that the most commonly disrupted miRNAs were miR-146a, miR-146b, miR-130, miR-122a, miR-342 and miR-409 (downregulated), and miR-29b, miR329, miR-199b, miR-382, miR-296, miR-221 and miR-92 (upregulated). Most importantly, transfection of miR-146a in a neuroblastoma cell line caused the downregulation of IL-1 receptor-associated kinase 1 (Irak1) levels, suggesting that the identified defect of miR-146a in Rett syndrome mice brains might be responsible for the observed upregulation of Irak1 in this model of the human disease. Overall, we provide another level of molecular deregulation occurring in Rett syndrome that might be useful for understanding the disease and for designing targeted therapies.


Assuntos
Proteína 2 de Ligação a Metil-CpG/deficiência , Proteína 2 de Ligação a Metil-CpG/genética , MicroRNAs/genética , MicroRNAs/metabolismo , Síndrome de Rett/genética , Síndrome de Rett/metabolismo , Animais , Sequência de Bases , Encéfalo/metabolismo , Linhagem Celular , Imunoprecipitação da Cromatina , Metilação de DNA , Primers do DNA/genética , Modelos Animais de Doenças , Feminino , Perfilação da Expressão Gênica , Humanos , Quinases Associadas a Receptores de Interleucina-1/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Análise de Sequência com Séries de Oligonucleotídeos , Processamento Pós-Transcricional do RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa
16.
Cancer Res ; 69(6): 2577-87, 2009 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-19244132

RESUMO

Cancer susceptibility is essentially attributable to multiple low-penetrance genes. Using interspecific consomic and congenic mice between the tumor-resistant SEG/Pas and the tumor-sensitive C57BL/6J strains, a region on chromosome 19 involved in the genetic resistance to gamma-irradiation-induced T-cell lymphomas (Tlyr1) has been identified. Through the development of nonoverlapping subcongenic strains, it has been further shown that Anxa1 may be a candidate resistance gene on the basis of its differential expression in thymus stroma cells after gamma-radiation exposure. In addition, thymus stroma cells of thymic lymphomas exhibited a significant reduction in the expression levels of Anxa1. Interestingly, the activity of Anxa1 relies on prostaglandin E(2) (PGE(2)) induction that brings about apoptosis in thymocytes. In fact, in vitro transfection experiments revealed that PGE(2) production was enhanced when HEK 293 cells were transfected with full-length cDNAs of Anxa1, with PGE(2) production in the cells transfected with the allele of the resistant strain (Anxa1(Tyr)) being higher than that in cells transfected with the allele of the susceptible strain (Anxa1(Phe)). Furthermore, the presence of this compound in the medium induced apoptosis of immature CD4(+)CD8(+)CD3(low) cells in a dose-dependent manner. These results improve our knowledge of the molecular mechanisms triggering T-cell lymphoblastic lymphoma development while highlighting the relevance of the stroma in controlling genetic susceptibility and the use of PGE(2) as a new therapeutic approach in T-cell hematologic malignancies.


Assuntos
Anexina A1/genética , Dinoprostona/metabolismo , Linfoma de Células T/genética , Neoplasias do Timo/genética , Animais , Mapeamento Cromossômico , Dinoprostona/biossíntese , Dinoprostona/farmacologia , Raios gama , Predisposição Genética para Doença , Perda de Heterozigosidade , Linfoma de Células T/patologia , Camundongos , Camundongos Endogâmicos C57BL , Neoplasias Induzidas por Radiação/genética , Neoplasias Induzidas por Radiação/patologia , Células Estromais/metabolismo , Células Estromais/patologia , Timo/efeitos dos fármacos , Timo/patologia , Timo/efeitos da radiação , Neoplasias do Timo/patologia , Transfecção
17.
Genome Res ; 19(3): 438-51, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19208682

RESUMO

The natural history of cancers associated with virus exposure is intriguing, since only a minority of human tissues infected with these viruses inevitably progress to cancer. However, the molecular reasons why the infection is controlled or instead progresses to subsequent stages of tumorigenesis are largely unknown. In this article, we provide the first complete DNA methylomes of double-stranded DNA viruses associated with human cancer that might provide important clues to help us understand the described process. Using bisulfite genomic sequencing of multiple clones, we have obtained the DNA methylation status of every CpG dinucleotide in the genome of the Human Papilloma Viruses 16 and 18 and Human Hepatitis B Virus, and in all the transcription start sites of the Epstein-Barr Virus. These viruses are associated with infectious diseases (such as hepatitis B and infectious mononucleosis) and the development of human tumors (cervical, hepatic, and nasopharyngeal cancers, and lymphoma), and are responsible for 1 million deaths worldwide every year. The DNA methylomes presented provide evidence of the dynamic nature of the epigenome in contrast to the genome. We observed that the DNA methylome of these viruses evolves from an unmethylated to a highly methylated genome in association with the progression of the disease, from asymptomatic healthy carriers, through chronically infected tissues and pre-malignant lesions, to the full-blown invasive tumor. The observed DNA methylation changes have a major functional impact on the biological behavior of the viruses.


Assuntos
Metilação de DNA , Vírus de DNA/genética , Genoma Viral , Neoplasias/virologia , Transformação Celular Viral/genética , Células Cultivadas , Mapeamento Cromossômico , Metilação de DNA/fisiologia , Vírus de DNA/metabolismo , DNA Viral/genética , DNA Viral/metabolismo , Feminino , Células HeLa , Vírus da Hepatite B/genética , Herpesvirus Humano 4/genética , Papillomavirus Humano 16/genética , Papillomavirus Humano 18/genética , Humanos , Neoplasias/genética
18.
PLoS One ; 3(11): e3669, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18989361

RESUMO

BACKGROUND: Rett syndrome (RTT) is a complex neurological disorder that is one of the most frequent causes of mental retardation in women. A great landmark in research in this field was the discovery of a relationship between the disease and the presence of mutations in the gene that codes for the methyl-CpG binding protein 2 (MeCP2). Currently, MeCP2 is thought to act as a transcriptional repressor that couples DNA methylation and transcriptional silencing. The present study aimed to identify new target genes regulated by Mecp2 in a mouse model of RTT. METHODOLOGY/PRINCIPAL FINDINGS: We have compared the gene expression profiles of wild type (WT) and Mecp2-null (KO) mice in three regions of the brain (cortex, midbrain, and cerebellum) by using cDNA microarrays. The results obtained were confirmed by quantitative real-time PCR. Subsequent chromatin immunoprecipitation assays revealed seven direct target genes of Mecp2 bound in vivo (Fkbp5, Mobp, Plagl1, Ddc, Mllt2h, Eya2, and S100a9), and three overexpressed genes due to an indirect effect of a lack of Mecp2 (Irak1, Prodh and Dlk1). The regions bound by Mecp2 were always methylated, suggesting the involvement of the methyl-CpG binding domain of the protein in the mechanism of interaction. CONCLUSIONS: We identified new genes that are overexpressed in Mecp2-KO mice and are excellent candidate genes for involvement in various features of the neurological disease. Our results demonstrate new targets of MeCP2 and provide us with a better understanding of the underlying mechanisms of RTT.


Assuntos
Proteína 2 de Ligação a Metil-CpG/genética , Síndrome de Rett/genética , Animais , Sítios de Ligação , Encéfalo/metabolismo , Imunoprecipitação da Cromatina , Metilação de DNA , Feminino , Expressão Gênica , Proteína 2 de Ligação a Metil-CpG/metabolismo , Camundongos , Camundongos Knockout , Regiões Promotoras Genéticas , Síndrome de Rett/metabolismo
19.
Cancer Res ; 68(11): 4116-22, 2008 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-18519670

RESUMO

An undifferentiated status and the epigenetic inactivation of tumor-suppressor genes are hallmarks of transformed cells. Promoter CpG island hypermethylation of differentiating genes, however, has rarely been reported. The Groucho homologue Transducin-like Enhancer of Split 1 (TLE1) is a multitasked transcriptional corepressor that acts through the acute myelogenous leukemia 1, Wnt, and Notch signaling pathways. We have found that TLE1 undergoes promoter CpG island hypermethylation-associated inactivation in hematologic malignancies, such as diffuse large B-cell lymphoma and AML. We also observed a mutual exclusivity of the epigenetic alteration of TLE1 and the cytogenetic alteration of AML1. TLE1 reintroduction in hypermethylated leukemia/lymphoma cells causes growth inhibition in colony assays and nude mice, whereas TLE1-short hairpin RNA depletion in unmethylated cells enhances tumor growth. We also show that these effects are mediated by TLE1 transcriptional repressor activity on its target genes, such as Cyclin D1, Colony-Stimulating Factor 1 receptor, and Hairy/Enhancer of Split 1. These data suggest that TLE1 epigenetic inactivation contributes to the development of hematologic malignancies by disrupting critical differentiation and growth-suppressing pathways.


Assuntos
Epigênese Genética , Neoplasias Hematológicas/genética , Proteínas Repressoras/genética , Animais , Sequência de Bases , Linhagem Celular Tumoral , Proteínas Correpressoras , Ilhas de CpG , Metilação de DNA , Primers do DNA , Humanos , Camundongos , Camundongos Nus , Reação em Cadeia da Polimerase Via Transcriptase Reversa
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