Assuntos
Neoplasias , Humanos , Neoplasias/tratamento farmacológico , Medicina de Precisão , OncologiaRESUMO
OBJECTIVES: Although high-throughput sequencing is revolutionising medicine, data on the actual cost of whole exome sequencing (WES) applications are needed. We aimed at assessing the cost of WES at a French cancer institute in 2015 and 2018. METHODS: Actual costs of WES application in oncology research were determined using both micro-costing and gross-costing for the years 2015 and 2018, before and after the acquisition of a new sequencer. The entire workflow process of a WES test was tracked, and the number and unit price of each resource were identified at the most detailed level, from library preparation to bioinformatics analyses. In addition, we conducted an ad hoc analysis of the bioinformatics storage costs of data issued from WES analyses. RESULTS: The cost of WES has decreased substantially, from 1921 per sample (i.e. cost of 3842 per patient) in 2015 to 804 per sample (i.e. cost of 1,608 per patient) in 2018, representing a decrease of 58%. In the meantime, the cost of bioinformatics storage has increased from 19,836 to 200,711. CONCLUSION: This study suggests that WES cost has decreased significantly in recent years. WES has become affordable, even though clinical utility and efficiency still need to be confirmed.
Assuntos
Neoplasias , Patologia Molecular , Custos e Análise de Custo , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Neoplasias/diagnóstico , Neoplasias/genética , Sequenciamento do ExomaAssuntos
Antimetabólitos Antineoplásicos/uso terapêutico , Azacitidina/análogos & derivados , Azacitidina/uso terapêutico , Leucemia Mielomonocítica Crônica/tratamento farmacológico , Adulto , Idoso , Metilação de DNA/efeitos dos fármacos , Decitabina , Feminino , Humanos , Leucemia Mielomonocítica Crônica/mortalidade , Masculino , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/tratamento farmacológico , Doenças Mieloproliferativas-Mielodisplásicas/tratamento farmacológico , Análise de Sobrevida , Resultado do TratamentoRESUMO
BACKGROUND: Patients diagnosed with therapy-related myeloid neoplasms (TRMN) with concomitant active neoplastic disorder (CAND) are usually proposed for best supportive care (BSC). We evaluated the feasibility of using 5-azacytidine (AZA) in this setting. METHODS: All patients referred to Gustave Roussy between 2010 and 2015 for TRMN diagnosis (less than 30% blast) and eligible for AZA treatment were included. Patients with CAND proposed for BSC were also described. Patient's outcomes were analyzed based on the presence or not of a CAND. RESULTS: Fifty-two patients with TRMN were analyzed, including 19 patients with CAND (14 eligible for AZA) and 33 without CAND eligible for AZA. The 5 patients with CAND ineligible for AZA had a worst performance status (p=0.016) at diagnosis and a shorter overall survival (OS) (0.62 months). Baseline characteristics of patients eligible for AZA were similar in the 2 groups except a trend for best performance status in patients with CAND (p=0.06). Overall response rate (71.4% vs 60.3%), transfusion independence (50.0% vs 45.5%) and OS (12.7 months vs 10.8 months) were similar between patients with and without CAND respectively (p=ns). CONCLUSION: Here we report the feasibility and efficacy of AZA for selected patients with TRMN and a CAND.
Assuntos
Azacitidina/uso terapêutico , Leucemia Mieloide Aguda/tratamento farmacológico , Segunda Neoplasia Primária/tratamento farmacológico , Neoplasias/complicações , Adulto , Idoso , Idoso de 80 Anos ou mais , Azacitidina/administração & dosagem , Feminino , Humanos , Leucemia Mieloide Aguda/complicações , Leucemia Mieloide Aguda/mortalidade , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Neoplasias/mortalidade , Neoplasias/patologia , Segunda Neoplasia Primária/complicações , Segunda Neoplasia Primária/mortalidade , Indução de Remissão , Estudos Retrospectivos , Taxa de Sobrevida , Resultado do TratamentoRESUMO
Graft versus host disease (GvHD), which is the primary complication of allogeneic bone marrow transplantation, can alter the intestinal barrier targeted by activated donor T-cells. Chemical inhibition of the stress protein HSP90 was demonstrated in vitro to inhibit T-cell activation and to modulate endoplasmic reticulum (ER) stress to which intestinal cells are highly susceptible. Since the HSP90 inhibitor 17-allylamino-demethoxygeldanamycin (17AAG) is developed in clinics, we explored here its ability to control intestinal acute GvHD in vivo in two mouse GvHD models (C57BL/6î²BALB/c and FVB/Nî²Lgr5-eGFP), ex vivo in intestine organoids and in vitro in intestinal epithelial cultures. We show that 17AAG decreases GvHD-associated mortality without impairing graft versus leukemia effect. While 17AAG effect in T-cell activation is just moderate at the dose used in vivo, we observe a striking intestinal integrity protection. At the intestine level, the drug promotes the splicing of the transcription factor X-box binding protein 1 (XBP1), which is a key component of the ER stress. This effect is associated with a decrease in intestinal damage and an increase in Lgr5(+) stem cells, Paneth cells and defensins production. The importance of XBP1 splicing control is further confirmed in cultured cells and organoids of primary intestinal epithelium where XBP1 is either shRNA depleted or inhibited with toyocamycin. In conclusion, 17AAG has a protective effect on the epithelial intestinal barrier in mouse models of acute GvHD. This compound deserves to be tested in the therapeutic control of acute GvHD.
Assuntos
Benzoquinonas/farmacologia , Citoproteção/efeitos dos fármacos , Doença Enxerto-Hospedeiro/tratamento farmacológico , Proteínas de Choque Térmico HSP90/antagonistas & inibidores , Intestinos/patologia , Lactamas Macrocíclicas/farmacologia , Nicho de Células-Tronco/efeitos dos fármacos , Animais , Benzoquinonas/uso terapêutico , Feminino , Doença Enxerto-Hospedeiro/genética , Doença Enxerto-Hospedeiro/patologia , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/patologia , Intestinos/efeitos dos fármacos , Lactamas Macrocíclicas/uso terapêutico , Camundongos , Camundongos Endogâmicos C57BL , Splicing de RNA/efeitos dos fármacos , Proteína 1 de Ligação a X-Box/genéticaRESUMO
Since its reclassification as a distinct disease entity, clinical research efforts have attempted to establish baseline characteristics and prognostic scoring systems for chronic myelomonocytic leukemia (CMML). Although existing data for baseline characteristics and CMML prognostication have been robustly developed and externally validated, these results have been limited by the small size of single-institution cohorts. We developed an international CMML data set that included 1832 cases across eight centers to establish the frequency of key clinical characteristics. Of note, we found that the majority of CMML patients were classified as World Health Organization CMML-1 and that a 7.5% bone marrow blast cut-point may discriminate prognosis with higher resolution in comparison with the existing 10%. We additionally interrogated existing CMML prognostic models and found that they are all valid and have comparable performance but are vulnerable to upstaging. Using random forest survival analysis for variable discovery, we demonstrated that the prognostic power of clinical variables alone is limited. Last, we confirmed the independent prognostic relevance of ASXL1 gene mutations and identified the novel adverse prognostic impact imparted by CBL mutations. Our data suggest that combinations of clinical and molecular information may be required to improve the accuracy of current CMML prognostication.
Assuntos
Leucemia Mielomonocítica Crônica/diagnóstico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Conjuntos de Dados como Assunto , Árvores de Decisões , Feminino , Predisposição Genética para Doença , Humanos , Cooperação Internacional , Estimativa de Kaplan-Meier , Leucemia Mielomonocítica Crônica/genética , Leucemia Mielomonocítica Crônica/mortalidade , Masculino , Pessoa de Meia-Idade , Mutação , Prognóstico , Curva ROC , Adulto JovemRESUMO
In patients with chronic myelomonocytic leukemia (CMML), age>65 years is an adverse prognostic factor. Our objective in the current study was to examine risk factors for survival and treatment outcome in 261 'young' adults with CMML, as defined by age ⩽65 years. In multivariable analysis, lower HB (P=0.01), higher circulating blast % (P=0.002), ASXL1 (P=0.0007) and SRSF2 mutations (P=0.008) and Mayo-French cytogenetic stratification (P=0.04) negatively impacted survival. Similarly, leukemia-free survival was independently affected by higher circulating blast % (P<0.0001), higher bone marrow blast % (P=0.0007) and the presence of circulating immature myeloid cells (P=0.0002). Seventy-five (29%) patients received hypomethylating agents (HMA), with the median number of cycles being 5, and the median duration of therapy being 5 months. The over-all response rate was 40% for azacitidine and 30% for decitabine. Fifty-three (24%) patients underwent an allogeneic hematopoietic stem cell transplant (AHSCT), with a response rate of 56% and a non-relapse mortality of 19%. Survival in young adults with CMML, although higher than in older patients, is poor and even worse in the presence of ASXL1 and SRSF2 mutations. Treatment outcome was more impressive with AHSCT than with HMA and neither was influenced by ASXL1/SRSF2 mutations or karyotype.
Assuntos
Leucemia Mielomonocítica Crônica/tratamento farmacológico , Leucemia Mielomonocítica Crônica/genética , Proteínas Nucleares/genética , Prognóstico , Ribonucleoproteínas/genética , Adulto , Intervalo Livre de Doença , Feminino , Humanos , Leucemia Mielomonocítica Crônica/epidemiologia , Leucemia Mielomonocítica Crônica/patologia , Masculino , Pessoa de Meia-Idade , Mutação , Fatores de Processamento de Serina-Arginina , Resultado do Tratamento , Adulto JovemRESUMO
In spite of the novel strategies to treat colon cancer, mortality rates associated with this disease remain consistently high. Tumour recurrence has been linked to the induction of resistance towards chemotherapy that involves cellular events that enable cancer cells to escape cell death. Treatment of colon cancer mainly implicates direct or indirect DNA-damaging agents and increased repair or tolerances towards subsequent lesions contribute to generate resistant populations. Resveratrol (RSV), a potent chemosensitising polyphenol, might share common properties with chemotherapeutic drugs through its indirect DNA-damaging effects reported in vitro. In this study, we investigated how RSV exerts its anticancer effects in models of colon cancer with a particular emphasis on the DNA-damage response (DDR; PIKKs-Chks-p53 signalling cascade) and its cellular consequences. We showed in vitro and in vivo that colon cancer models could progressively escape the repeated pharmacological treatments with RSV. We observed for the first time that this response was correlated with transient activation of the DDR, of apoptosis and senescence. In vitro, a single treatment with RSV induced a DDR correlated with S-phase delay and apoptosis, but prolonged treatments led to transient micronucleations and senescence phenotypes associated with polyploidisation. Ultimately, stable resistant populations towards RSV displaying higher degrees of ploidy and macronucleation as compared to parental cells emerged. We linked these transient effects and resistance emergence to the abilities of these cells to progressively escape RSV-induced DNA damage. Finally, we demonstrated that this DNA damage was triggered by an overproduction of reactive oxygen species (ROS) against which cancer cells could adapt under prolonged exposure to RSV. This study provides a pre-clinical analysis of the long-term effects of RSV and highlights ROS as main agents in RSV's indirect DNA-damaging properties and consequences in terms of anticancer response and potent resistance emergence.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Colo/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Regulação Neoplásica da Expressão Gênica , Espécies Reativas de Oxigênio/metabolismo , Estilbenos/farmacologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Linhagem Celular Tumoral , Quinase 1 do Ponto de Checagem , Quinase do Ponto de Checagem 2/genética , Quinase do Ponto de Checagem 2/metabolismo , Colo/metabolismo , Colo/patologia , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/genética , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Dano ao DNA , Histonas/genética , Histonas/metabolismo , Humanos , Poliploidia , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Ratos , Resveratrol , Fase S/efeitos dos fármacos , Fase S/genética , Transdução de Sinais , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
In a cohort of 466 patients, we sought to clarify the prognostic relevance of ASXL1 and SETBP1 mutations, among others, in World Health Organization-defined chronic myelomonocytic leukemia (CMML) and its added value to the Mayo prognostic model. In univariate analysis, survival was adversely affected by ASXL1 (nonsense and frameshift) but not SETBP1 mutations. In multivariable analysis, ASXL1 mutations, absolute monocyte count >10 × 10(9)/l, hemoglobin <10 g/dl, platelets <100 × 10(9)/l and circulating immature myeloid cells were independently predictive of shortened survival: hazard ratio (95% confidence interval (CI)) values were 1.5 (1.1-2.0), 2.2 (1.6-3.1), 2.0 (1.6-2.6), 1.5 (1.2-1.9) and 2.0 (1.4-2.7), respectively. A regression coefficient-based prognostic model based on these five risk factors delineated high (≥3 risk factors; HR 6.2, 95% CI 3.7-10.4) intermediate-2 (2 risk factors; HR 3.4, 95% CI 2.0-5.6) intermediate-1 (one risk factor; HR 1.9, 95% CI 1.1-3.3) and low (no risk factors) risk categories with median survivals of 16, 31, 59 and 97 months, respectively. Neither ASXL1 nor SETBP1 mutations predicted leukemic transformation. The current study confirms the independent prognostic value of nonsense/frameshift ASXL1 mutations in CMML and signifies its added value to the Mayo prognostic model, as had been shown previously in the French consortium model.
Assuntos
Proteínas de Transporte/genética , Leucemia Mielomonocítica Crônica/genética , Leucemia Mielomonocítica Crônica/mortalidade , Proteínas Nucleares/genética , Proteínas Repressoras/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Códon sem Sentido , Feminino , Mutação da Fase de Leitura , Testes Genéticos , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Estatísticos , Análise Multivariada , Prognóstico , Fatores de Risco , Análise de Sobrevida , Adulto JovemRESUMO
In addition to their cytoprotective role in stressful conditions, heat shock proteins (HSPs) are involved in specific differentiation pathways, for example, we have identified a role for HSP90 in macrophage differentiation of human peripheral blood monocytes that are exposed to macrophage colony-stimulating factor (M-CSF). Here, we show that deletion of the main transcription factor involved in heat shock gene regulation, heat shock factor 1 (HSF1), affects M-CSF-driven differentiation of mouse bone marrow cells. HSF1 transiently accumulates in the nucleus of human monocytes undergoing macrophage differentiation, including M-CSF-treated peripheral blood monocytes and phorbol ester-treated THP1 cells. We demonstrate that HSF1 has a dual effect on SPI1/PU.1, a transcription factor essential for macrophage differentiation and whose deregulation can lead to the development of leukemias and lymphomas. Firstly, HSF1 regulates SPI1/PU.1 gene expression through its binding to a heat shock element within the intron 2 of this gene. Furthermore, downregulation or inhibition of HSF1 impaired both SPI1/PU.1-targeted gene transcription and macrophage differentiation. Secondly, HSF1 induces the expression of HSP70 that interacts with SPI1/PU.1 to protect the transcription factor from proteasomal degradation. Taken together, HSF1 appears as a fine-tuning regulator of SPI1/PU.1 expression at the transcriptional and post-translational levels during macrophage differentiation of monocytes.
Assuntos
Diferenciação Celular , Proteínas de Ligação a DNA/fisiologia , Macrófagos/citologia , Monócitos/citologia , Proteínas Proto-Oncogênicas/genética , Transativadores/genética , Fatores de Transcrição/fisiologia , Animais , Antígenos CD/análise , Antígenos de Diferenciação Mielomonocítica/análise , Células Cultivadas , Regulação da Expressão Gênica , Fatores de Transcrição de Choque Térmico , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Complexo de Endopeptidases do Proteassoma/metabolismo , Receptores de Superfície Celular/análiseRESUMO
Tumour necrosis factor-α (TNF) is a cytokine endowed with multiple functions, depending on the cellular and environmental context. TNF receptor engagement induces the formation of a multimolecular complex including the TNFR-associated factor TRAF2, the receptor-interaction protein kinase RIP1 and the cellular inhibitor of apoptosis cIAP1, the latter being essential for NF-κB activation. Here, we show that cIAP1 also regulates TNF-induced actin cytoskeleton reorganization through a cdc42-dependent, NF-κB-independent pathway. Deletion of cIAP1 prevents TNF-induced filopodia and cdc42 activation. The expression of cIAP1 or its E3-ubiquitin ligase-defective mutant restores the ability of cIAP1(-/-) MEFs to produce filopodia, whereas a cIAP1 mutant unable to bind TRAF2 does not. Accordingly, the silencing of TRAF2 inhibits TNF-mediated filopodia formation, whereas silencing of RIP1 does not. cIAP1 directly binds cdc42 and promotes its RhoGDIα-mediated stabilization. TNF decreases cIAP1-cdc42 interaction, suggesting that TNF-induced recruitment of cIAP1/TRAF2 to the receptor releases cdc42, which in turn triggers actin remodeling. cIAP1 also regulates cdc42 activation in response to EGF and HRas-V12 expression. A downregulation of cIAP1 altered the cell polarization, the cell adhesion to endothelial cells and cell intercalation, which are cdc42-dependent processes. Finally, we demonstrated that the deletion of cIAP1 regulated the HRas-V12-mediated transformation process, including anchorage-dependent cell growth, tumour growth in a xenograft model and the development of experimental metastasis in the lung.
Assuntos
Citoesqueleto de Actina/metabolismo , Proteínas Inibidoras de Apoptose/metabolismo , Pseudópodes/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Proteína cdc42 de Ligação ao GTP/metabolismo , Animais , Western Blotting , Adesão Celular/fisiologia , Polaridade Celular/fisiologia , Modelos Animais de Doenças , Imunofluorescência , Células HEK293 , Xenoenxertos , Humanos , Imunoprecipitação , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Camundongos , Células NIH 3T3 , Invasividade Neoplásica/patologia , Transdução de Sinais/fisiologia , Ressonância de Plasmônio de Superfície , TransfecçãoRESUMO
Ten-Eleven Translocation-2 (TET2) inactivation through loss-of-function mutation, deletion and IDH1/2 (Isocitrate Dehydrogenase 1 and 2) gene mutation is a common event in myeloid and lymphoid malignancies. TET2 gene mutations similar to those observed in myeloid and lymphoid malignancies also accumulate with age in otherwise healthy subjects with clonal hematopoiesis. TET2 is one of the three proteins of the TET (Ten-Eleven Translocation) family, which are evolutionarily conserved dioxygenases that catalyze the conversion of 5-methyl-cytosine (5-mC) to 5-hydroxymethyl-cytosine (5-hmC) and promote DNA demethylation. TET dioxygenases require 2-oxoglutarate, oxygen and Fe(II) for their activity, which is enhanced in the presence of ascorbic acid. TET2 is the most expressed TET gene in the hematopoietic tissue, especially in hematopoietic stem cells. In addition to their hydroxylase activity, TET proteins recruit the O-linked ß-D-N-acetylglucosamine (O-GlcNAc) transferase (OGT) enzyme to chromatin, which promotes post-transcriptional modifications of histones and facilitates gene expression. The TET2 level is regulated by interaction with IDAX, originating from TET2 gene fission during evolution, and by the microRNA miR-22. TET2 has pleiotropic roles during hematopoiesis, including stem-cell self-renewal, lineage commitment and terminal differentiation of monocytes. Analysis of Tet2 knockout mice, which are viable and fertile, demonstrated that Tet2 functions as a tumor suppressor whose haploinsufficiency initiates myeloid and lymphoid transformations. This review summarizes the recently identified TET2 physiological and pathological functions and discusses how this knowledge influences our therapeutic approaches in hematological malignancies and possibly other tumor types.
Assuntos
Proteínas de Ligação a DNA/genética , Doenças Hematológicas/genética , Hematopoese/genética , Proteínas Proto-Oncogênicas/genética , Envelhecimento/genética , Ácido Ascórbico/metabolismo , Metilação de DNA , Proteínas de Ligação a DNA/metabolismo , Dioxigenases , Células-Tronco Embrionárias/metabolismo , Epigênese Genética , Genes Supressores de Tumor , Humanos , MicroRNAs/fisiologia , Mutação , Proteínas Proto-Oncogênicas/metabolismoAssuntos
Haplótipos , Janus Quinase 2/genética , Mutação , Policitemia Vera/genética , Policitemia Vera/metabolismo , Alelos , Evolução Clonal , Células-Tronco Hematopoéticas/efeitos dos fármacos , Células-Tronco Hematopoéticas/metabolismo , Humanos , Interferon-alfa/uso terapêutico , Modelos Biológicos , Policitemia Vera/tratamento farmacológicoRESUMO
Extranodal, nasal-type natural killer (NK)/T-cell lymphoma (NKCL) is an aggressive malignancy with poor prognosis in which, usually, signal transducer and activator of transcription 3 (STAT3) is constitutively activated and oncogenic. Here, we demonstrate that STAT3 activation mostly results from constitutive Janus kinase (JAK)3 phosphorylation on tyrosine 980, as observed in three of the four tested NKCL cell lines and in 20 of the 23 NKCL tumor samples under study. In one of the cell lines and in 4 of 19 (21%) NKCL primary tumor samples, constitutive JAK3 activation was related to an acquired mutation (A573V or V722I) in the JAK3 pseudokinase domain. We then show that constitutive activation of the JAK3/STAT3 pathway has a major role in NKCL cell growth and survival and in the invasive phenotype. Indeed, NKCL cell growth was slowed down in vitro by targeting JAK3 with chemical inhibitors or small-interfering RNAs. In a human NKCL xenograft mouse model, tumor growth was significantly delayed by the JAK3 inhibitor CP-690550. Altogether, the constitutive activation of JAK3, which can result from JAK3-activating mutations, is a frequent feature of NKCL that deserves to be tested as a therapeutic target.
Assuntos
Janus Quinase 3/genética , Linfoma Extranodal de Células T-NK/genética , Linfoma Extranodal de Células T-NK/patologia , Mutação , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Estudos de Casos e Controles , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular/genética , Modelos Animais de Doenças , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Janus Quinase 3/antagonistas & inibidores , Janus Quinase 3/metabolismo , Linfoma Extranodal de Células T-NK/tratamento farmacológico , Linfoma Extranodal de Células T-NK/metabolismo , Masculino , Camundongos , Pessoa de Meia-Idade , Invasividade Neoplásica , Metástase Neoplásica , Estadiamento de Neoplasias , Fosforilação , Piperidinas/administração & dosagem , Piperidinas/farmacologia , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/farmacologia , Pirimidinas/administração & dosagem , Pirimidinas/farmacologia , Pirróis/administração & dosagem , Pirróis/farmacologia , Carga Tumoral/efeitos dos fármacos , Carga Tumoral/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Abexinostat is a pan histone deacetylase inhibitor (HDACi) that demonstrates efficacy in malignancy treatment. Like other HDACi, this drug induces a profound thrombocytopenia whose mechanism is only partially understood. We have analyzed its effect at doses reached in patient plasma on in vitro megakaryopoiesis derived from human CD34(+) cells. When added at day 0 in culture, abexinostat inhibited CFU-MK growth, megakaryocyte (MK) proliferation and differentiation. These effects required only a short incubation period. Decreased proliferation was due to induction of apoptosis and was not related to a defect in TPO/MPL/JAK2/STAT signaling. When added later (day 8), the compound induced a dose-dependent decrease (up to 10-fold) in proplatelet (PPT) formation. Gene profiling from MK revealed a silencing in the expression of DNA repair genes with a marked RAD51 decrease at protein level. DNA double-strand breaks were increased as attested by elevated γH2AX phosphorylation level. Moreover, ATM was phosphorylated leading to p53 stabilization and increased BAX and p21 expression. The use of a p53 shRNA rescued apoptosis, and only partially the defect in PPT formation. These results suggest that HDACi induces a thrombocytopenia by a p53-dependent mechanism along MK differentiation and a p53-dependent and -independent mechanism for PPT formation.