RESUMO
BACKGROUND: Hickman-type tunnelled catheters (Hickman), peripherally inserted central catheters (PICCs), and totally implanted ports (PORTs) are used to deliver systemic anticancer treatment (SACT) via a central vein. We aimed to compare complication rates and costs of the three devices to establish acceptability, clinical effectiveness, and cost-effectiveness of the devices for patients receiving SACT. METHODS: We did an open-label, multicentre, randomised controlled trial (Cancer and Venous Access [CAVA]) of three central venous access devices: PICCs versus Hickman (non-inferiority; 10% margin); PORTs versus Hickman (superiority; 15% margin); and PORTs versus PICCs (superiority; 15% margin). Adults (aged ≥18 years) receiving SACT (≥12 weeks) for solid or haematological malignancy from 18 oncology units in the UK were included. Four randomisation options were available: Hickman versus PICCs versus PORTs (2:2:1), PICCs versus Hickman (1:1), PORTs versus Hickman (1:1), and PORTs versus PICCs (1:1). Randomisation was done using a minimisation algorithm stratifying by centre, body-mass index, type of cancer, device history, and treatment mode. The primary outcome was complication rate (composite of infection, venous thrombosis, pulmonary embolus, inability to aspirate blood, mechanical failure, and other) assessed until device removal, withdrawal from study, or 1-year follow-up. This study is registered with ISRCTN, ISRCTN44504648. FINDINGS: Between Nov 8, 2013, and Feb 28, 2018, of 2714 individuals screened for eligibility, 1061 were enrolled and randomly assigned, contributing to the relevant comparison or comparisons (PICC vs Hickman n=424, 212 [50%] on PICC and 212 [50%] on Hickman; PORT vs Hickman n=556, 253 [46%] on PORT and 303 [54%] on Hickman; and PORT vs PICC n=346, 147 [42%] on PORT and 199 [58%] on PICC). Similar complication rates were observed for PICCs (110 [52%] of 212) and Hickman (103 [49%] of 212). Although the observed difference was less than 10%, non-inferiority of PICCs was not confirmed (odds ratio [OR] 1·15 [95% CI 0·78-1·71]) potentially due to inadequate power. PORTs were superior to Hickman with a complication rate of 29% (73 of 253) versus 43% (131 of 303; OR 0·54 [95% CI 0·37-0·77]). PORTs were superior to PICCs with a complication rate of 32% (47 of 147) versus 47% (93 of 199; OR 0·52 [0·33-0·83]). INTERPRETATION: For most patients receiving SACT, PORTs are more effective and safer than both Hickman and PICCs. Our findings suggest that most patients receiving SACT for solid tumours should receive a PORT within the UK National Health Service. FUNDING: UK National Institute for Health Research Health Technology Assessment Programme.
Assuntos
Antineoplásicos/administração & dosagem , Cateterismo Periférico , Cateteres de Demora , Cateteres Venosos Centrais , Neoplasias/tratamento farmacológico , Dispositivos de Acesso Vascular , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/uso terapêutico , Infecções Relacionadas a Cateter/etiologia , Cateterismo Periférico/efeitos adversos , Cateteres de Demora/efeitos adversos , Cateteres de Demora/economia , Cateteres Venosos Centrais/efeitos adversos , Cateteres Venosos Centrais/economia , Análise Custo-Benefício , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dispositivos de Acesso Vascular/economia , Adulto JovemRESUMO
Removal of the assembly factor eukaryotic initiation factor 6 (eIF6) is critical for late cytoplasmic maturation of 60S ribosomal subunits. In mammalian cells, the current model posits that eIF6 release is triggered following phosphorylation of Ser 235 by activated protein kinase C. In contrast, genetic studies in yeast indicate a requirement for the ortholog of the SBDS (Shwachman-Bodian-Diamond syndrome) gene that is mutated in the inherited leukemia predisposition disorder Shwachman-Diamond syndrome (SDS). Here, by isolating late cytoplasmic 60S ribosomal subunits from Sbds-deleted mice, we show that SBDS and the GTPase elongation factor-like 1 (EFL1) directly catalyze eIF6 removal in mammalian cells by a mechanism that requires GTP binding and hydrolysis by EFL1 but not phosphorylation of eIF6 Ser 235. Functional analysis of disease-associated missense variants reveals that the essential role of SBDS is to tightly couple GTP hydrolysis by EFL1 on the ribosome to eIF6 release. Furthermore, complementary NMR spectroscopic studies suggest unanticipated mechanistic parallels between this late step in 60S maturation and aspects of bacterial ribosome disassembly. Our findings establish a direct role for SBDS and EFL1 in catalyzing the translational activation of ribosomes in all eukaryotes, and define SDS as a ribosomopathy caused by uncoupling GTP hydrolysis from eIF6 release.
Assuntos
Fatores de Iniciação em Eucariotos/metabolismo , Guanosina Trifosfato/metabolismo , Ribossomos/patologia , Animais , Doenças da Medula Óssea/genética , Doenças da Medula Óssea/fisiopatologia , Catálise , Células Cultivadas , Modelos Animais de Doenças , Fatores de Iniciação em Eucariotos/genética , Insuficiência Pancreática Exócrina/genética , Insuficiência Pancreática Exócrina/fisiopatologia , Humanos , Hidrólise , Lipomatose , Fígado/patologia , Camundongos , Camundongos Endogâmicos C57BL , Modelos Moleculares , Mutação , Fatores de Iniciação de Peptídeos/genética , Fatores de Iniciação de Peptídeos/metabolismo , Fosforilação , Ligação Proteica , Estrutura Terciária de Proteína , Proteínas/química , Proteínas/genética , Proteínas/metabolismo , Subunidades Ribossômicas Maiores de Eucariotos , Síndrome de Shwachman-DiamondRESUMO
The developmental switch from human fetal (gamma) to adult (beta) hemoglobin represents a clinically important example of developmental gene regulation. The transcription factor BCL11A is a central mediator of gamma-globin silencing and hemoglobin switching. Here we determine chromatin occupancy of BCL11A at the human beta-globin locus and other genomic regions in vivo by high-resolution chromatin immunoprecipitation (ChIP)-chip analysis. BCL11A binds the upstream locus control region (LCR), epsilon-globin, and the intergenic regions between gamma-globin and delta-globin genes. A chromosome conformation capture (3C) assay shows that BCL11A reconfigures the beta-globin cluster by modulating chromosomal loop formation. We also show that BCL11A and the HMG-box-containing transcription factor SOX6 interact physically and functionally during erythroid maturation. BCL11A and SOX6 co-occupy the human beta-globin cluster along with GATA1, and cooperate in silencing gamma-globin transcription in adult human erythroid progenitors. These findings collectively demonstrate that transcriptional silencing of gamma-globin genes by BCL11A involves long-range interactions and cooperation with SOX6. Our findings provide insight into the mechanism of BCL11A action and new clues for the developmental gene regulatory programs that function at the beta-globin locus.
Assuntos
Proteínas de Transporte/metabolismo , Células Eritroides/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Inativação Gênica , Proteínas Nucleares/metabolismo , Fatores de Transcrição SOXD/metabolismo , gama-Globinas/metabolismo , Adulto , Animais , Linhagem Celular , Células Eritroides/citologia , Eritropoese/fisiologia , Fator de Transcrição GATA1/metabolismo , Histonas/metabolismo , Humanos , Camundongos , Ligação Proteica , Transporte Proteico , Proteínas RepressorasRESUMO
The autosomal recessive disorder Shwachman-Diamond syndrome, characterized by bone marrow failure and leukemia predisposition, is caused by deficiency of the highly conserved Shwachman-Bodian-Diamond syndrome (SBDS) protein. Here, we identify the function of the yeast SBDS ortholog Sdo1, showing that it is critical for the release and recycling of the nucleolar shuttling factor Tif6 from pre-60S ribosomes, a key step in 60S maturation and translational activation of ribosomes. Using genome-wide synthetic genetic array mapping, we identified multiple TIF6 gain-of-function alleles that suppressed the pre-60S nuclear export defects and cytoplasmic mislocalization of Tif6 observed in sdo1Delta cells. Sdo1 appears to function within a pathway containing elongation factor-like 1, and together they control translational activation of ribosomes. Thus, our data link defective late 60S ribosomal subunit maturation to an inherited bone marrow failure syndrome associated with leukemia predisposition.
Assuntos
Biossíntese de Proteínas/genética , Ribossomos/metabolismo , Proteínas de Saccharomyces cerevisiae/fisiologia , Saccharomyces cerevisiae/genética , Proteínas de Transporte/genética , GTP Fosfo-Hidrolases/genética , GTP Fosfo-Hidrolases/fisiologia , Deleção de Genes , Proteínas de Filamentos Intermediários/genética , Modelos Biológicos , Modelos Moleculares , Mutação , Organismos Geneticamente Modificados , Fatores de Alongamento de Peptídeos/genética , Fatores de Alongamento de Peptídeos/fisiologia , Fosfoproteínas/genética , Biossíntese de Proteínas/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Proteínas Ribossômicas , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/genéticaRESUMO
Trisomy 21 is associated with hematopoietic abnormalities in the fetal liver, a preleukemic condition termed transient myeloproliferative disorder, and increased incidence of acute megakaryoblastic leukemia. Human trisomy 21 pluripotent cells of various origins, human embryonic stem (hES), and induced pluripotent stem (iPS) cells, were differentiated in vitro as a model to recapitulate the effects of trisomy on hematopoiesis. To mitigate clonal variation, we isolated disomic and trisomic subclones from the same parental iPS line, thereby generating subclones isogenic except for chromosome 21. Under differentiation conditions favoring development of fetal liver-like, γ-globin expressing, definitive hematopoiesis, we found that trisomic cells of hES, iPS, or isogenic origins exhibited a two- to fivefold increase in a population of CD43(+)(Leukosialin)/CD235(+)(Glycophorin A) hematopoietic cells, accompanied by increased multilineage colony-forming potential in colony-forming assays. These findings establish an intrinsic disturbance of multilineage myeloid hematopoiesis in trisomy 21 at the fetal liver stage.
Assuntos
Diferenciação Celular , Síndrome de Down , Hematopoese , Células-Tronco Pluripotentes/citologia , Perfilação da Expressão Gênica , Humanos , Cariotipagem , Reação em Cadeia da PolimeraseRESUMO
Many human aneuploidy syndromes have unique phenotypic consequences, but in most instances it is unclear whether these phenotypes are attributable to alterations in the dosage of specific genes. In human trisomy 13, there is delayed switching and persistence of fetal hemoglobin (HbF) and elevation of embryonic hemoglobin in newborns. Using partial trisomy cases, we mapped this trait to chromosomal band 13q14; by examining the genes in this region, two microRNAs, miR-15a and -16-1, appear as top candidates for the elevated HbF levels. Indeed, increased expression of these microRNAs in primary human erythroid progenitor cells results in elevated fetal and embryonic hemoglobin gene expression. Moreover, we show that a direct target of these microRNAs, MYB, plays an important role in silencing the fetal and embryonic hemoglobin genes. Thus we demonstrate how the developmental regulation of a clinically important human trait can be better understood through the genetic and functional study of aneuploidy syndromes and suggest that miR-15a, -16-1, and MYB may be important therapeutic targets to increase HbF levels in patients with sickle cell disease and ß-thalassemia.
Assuntos
Cromossomos Humanos Par 13/genética , Hemoglobina Fetal/genética , MicroRNAs/genética , Proteínas Proto-Oncogênicas c-myb/genética , Trissomia , Algoritmos , Antígenos CD/metabolismo , Sequência de Bases , Western Blotting , Células Precursoras Eritroides/metabolismo , Feminino , Hemoglobina Fetal/metabolismo , Perfilação da Expressão Gênica , Células HEK293 , Humanos , Lactente , Recém-Nascido , Células K562 , Masculino , Modelos Genéticos , Dados de Sequência Molecular , Análise de Sequência com Séries de Oligonucleotídeos , Receptores da Transferrina/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
BACKGROUND: The outcome of chemotherapy in patients older than 40 years with acute lymphoblastic leukaemia is poor and myeloablative allogeneic haematopoietic stem-cell transplantation (HSCT) has a high transplant-related mortality (TRM) in this age cohort. The aim of this study was to assess the activity and safety of reduced-intensity conditioned allogeneic HSCT in this patient population. METHODS: This was a single-arm, prospective study within the UKALL14 trial done in 46 centres in the UK, which recruited patients to the transplantation substudy. Participants in UKALL14 had B-cell or T-cell acute lymphoblastic leukaemia, were aged 25-65 years (BCR-ABL1-negative) or 18-65 years (BCR-ABL1-positive), and for this subcohort had a fit, matched sibling donor or an 8 out of 8 allelic matched unrelated donor (HLA-A, HLA-B, HLA-C, and HLA-DR). On June 20, 2014, the protocol was amended to allow 7 out of 8 matched unrelated donors if the patient had high risk cytogenetics or was minimal residual disease (MRD)-positive after the second induction course. Patients were given fludarabine, melphalan, and alemtuzumab (FMA; intravenous fludarabine 30 mg/m2 on days -6 to -2, melphalan 140 mg/m2 on day -2, and alemtuzumab 30 mg on day -1 [sibling donor] and days -2 and -1 [unrelated donor]) before allogeneic HSCT (aged ≥41 years patient pathway). Donor lymphocyte infusions were given from 6 months for mixed chimerism or MRD. The primary endpoint was event-free survival and secondary and transplantation-specific endpoints included overall survival, relapse incidence, TRM, and acute and chronic graft-versus-host disease (GVHD). This study is registered with ClinicalTrials.gov, NCT01085617. FINDINGS: From Feb 22, 2011, to July 26, 2018, 249 patients (236 aged ≥41 years and 13 younger than 41 years) considered unfit for a myeloablative allograft received an FMA reduced-intensity conditioned HSCT. 138 (55%) patients were male and 111 (45%) were female. 88 (35%) participants received transplantations from a sibling donor and 160 (64%) received transplantations from unrelated donors. 211 (85%) participants had B-precursor acute lymphoblastic leukaemia. High-risk cytogenetics were present in 43 (22%) and another 63 (25%) participants were BCR-ABL1-positive. At median follow-up of 49 months (IQR 36-70), 4-year event-free survival was 46·8% (95% CI 40·1-53·2) and 4-year overall survival was 54·8% (48·0-61·2). 4-year cumulative incidence of relapse was 33·6% (27·9-40·2) and 4-year TRM was 19·6% (15·1-25·3). 27 (56%) of 48 patients with TRM had infection as the named cause of death. Seven (15%) of 48 patients had fungal infections, 13 (27%) patients had bacterial infections (six gram-negative), and 11 (23%) had viral infections (three cytomegalovirus and two Epstein-Barr virus). Acute GVHD grade 2-4 occurred in 29 (12%) of 247 patients and grade 3-4 occurred in 12 (5%) patients. Chronic GVHD incidence was 84 (37%) of 228 patients (50 [22%] had extensive chronic GVHD). 49 (30%) of 162 patients had detectable end-of-induction MRD, which portended worse outcomes with event-free survival (HR 2·40 [95% CI 1·46-3·93]) and time-to-relapse (HR 2·41 [1·29-4·48]). INTERPRETATION: FMA reduced-intensity conditioned allogeneic HSCT in older patients with acute lymphoblastic leukaemia in first complete remission provided good disease control with moderate GVHD, resulting in better-than-expected event-free survival and overall survival in this high-risk population. Strategies to reduce infection-related TRM will further improve outcomes. FUNDING: Cancer Research UK.
Assuntos
Infecções por Vírus Epstein-Barr , Transplante de Células-Tronco Hematopoéticas , Leucemia-Linfoma Linfoblástico de Células Precursoras , Adulto , Idoso , Feminino , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Transplante de Células-Tronco Hematopoéticas/métodos , Herpesvirus Humano 4 , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Estudos Prospectivos , Linfócitos T , Doadores não RelacionadosRESUMO
BACKGROUND: Treatment for adults with acute lymphoblastic leukaemia requires improvement. UKALL14 was a UK National Cancer Research Institute Adult ALL group study that aimed to determine the benefit of adding the anti-CD20 monoclonal antibody, rituximab, to the therapy of adults with de novo B-precursor acute lymphoblastic leukaemia. METHODS: This was an investigator-initiated, phase 3, randomised controlled trial done in all UK National Health Service Centres treating patients with acute lymphoblastic leukaemia (65 centres). Patients were aged 25-65 years with de-novo BCR-ABL1-negative acute lymphoblastic leukaemia. Patients with de-novo BCR-ABL1-positive acute lymphoblastic leukaemia were eligible if they were aged 19-65 years. Participants were randomly assigned (1:1) to standard-of-care induction therapy or standard-of-care induction therapy plus four doses of intravenous rituximab (375 mg/m2 on days 3, 10, 17, and 24). Randomisation used minimisation and was stratified by sex, age, and white blood cell count. No masking was used for patients, clinicians, or staff (including the trial statistician), although the central laboratory analysing minimal residual disease and CD20 was masked to treatment allocation. The primary endpoint was event-free survival in the intention-to-treat population. Safety was assessed in all participants who started trial treatment. This study is registered with ClincialTrials.gov, NCT01085617. FINDINGS: Between April 19, 2012, and July 10, 2017, 586 patients were randomly assigned to standard of care (n=292) or standard of care plus rituximab (n=294). Nine patients were excluded from the final analysis due to misdiagnosis (standard of care n=4, standard of care plus rituximab n=5). In the standard-of-care group, median age was 45 years (IQR 22-65), 159 (55%) of 292 participants were male, 128 (44%) were female, one (<1%) was intersex, and 143 (59%) of 244 participants had high-risk cytogenetics. In the standard-of-care plus rituximab group, median age was 46 years (IQR 23-65), 159 (55%) of 294 participants were male, 130 (45%) were female, and 140 (60%) of 235 participants had high-risk cytogenetics. After a median follow-up of 53·7 months (IQR 40·3-70·4), 3-year event-free survival was 43·7% (95% CI 37·8-49·5) for standard of care versus 51·4% (45·4-57·1) for standard of care plus rituximab (hazard ratio [HR] 0·85 [95% CI 0·69-1·06]; p=0·14). The most common adverse events were infections and cytopenias, with no difference between the groups in the rates of adverse events. There were 11 (4%) fatal (grade 5) events in induction phases 1 and 2 in the standard-of-care group and 13 (5%) events in the standard-of-care plus rituximab group). 3-year non-relapse mortality was 23·7% (95% CI 19·0-29·4) in the standard-of-care group versus 20·6% (16·2-25·9) in the standard-of-care plus rituximab group (HR 0·88 [95% CI 0·62-1·26]; p=0·49). INTERPRETATION: Standard of care plus four doses of rituximab did not significantly improve event-free survival over standard of care. Rituximab is beneficial in acute lymphoblastic leukaemia but four doses during induction is likely to be insufficient. FUNDING: Cancer Research UK and Blood Cancer UK.
Assuntos
Quimioterapia de Indução , Leucemia-Linfoma Linfoblástico de Células Precursoras , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Células Precursoras de Linfócitos B , Rituximab/efeitos adversos , Medicina Estatal , Adulto JovemRESUMO
IKZF1 deletions (ΔIKZF1) are commonly detected in B-precursor acute lymphoblastic leukemia (ALL; B-ALL) and are widely assumed to have a significant impact on outcome. We compared the ability of multiplex ligand-dependent probe amplification (MLPA) and polymerase chain reaction (PCR) to detect ΔIKZF1 and to determine the impact on event-free survival of patients with precursor B-ALL aged 23 to 65 years recruited to the completed trial UKALL14 (ISRCTN 66541317). From 655 recruits with BCR-ABL1+ and BCR-ABL1- B-ALL, all available diagnostic DNA samples (76% of the recruited population) were screened by multiplex end point PCR covering 4 deletions: dominant-negative (DN) Δ4-7 or the loss of function Δ2-7, Δ4-8, and Δ2-8 (n = 498), MLPA (n = 436), or by both (n = 420). Although patients with BCR-ABL1- ΔIKZF1 were more likely to have minimal residual disease at the end of induction, we did not find any impact of ΔIKZF1 (including subgroup analysis for DN or loss-of-function lesions) or the IKZF1plus genotype on event-free, overall survival, or relapse risk by univariable or multivariable analyses. Consistent with the technical approach, MLPA not only detected a wider range of deletions than PCR but also failed to detect some PCR-detected lesions. The main difference between our study and others reporting an association between ΔIKZF1 and outcome is the older age of participants in our population. The impact of ΔIKZF1 in ALL may be less marked in an older population of patients. Our study underscores the need for analyses in large, harmonized data sets. This trial was registered at www.clinicaltrials.gov as #NCT01085617.
Assuntos
Linfoma de Burkitt , Leucemia-Linfoma Linfoblástico de Células Precursoras , Adulto , Idoso , Proteínas de Fusão bcr-abl/genética , Humanos , Fator de Transcrição Ikaros/genética , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/genéticaRESUMO
OBJECTIVE: To evaluate the effect of different treatment strategies on enterohaemorrhagic Escherichia coli O104:H4 induced haemolytic uraemic syndrome. DESIGN: Multicentre retrospective case-control study. SETTING: 23 hospitals in northern Germany. PARTICIPANTS: 298 adults with enterohaemorrhagic E coli induced haemolytic uraemic syndrome. MAIN OUTCOME MEASURES: Dialysis, seizures, mechanical ventilation, abdominal surgery owing to perforation of the bowel or bowel necrosis, and death. RESULTS: 160 of the 298 patients (54%) temporarily required dialysis, with only three needing treatment long term. 37 patients (12%) had seizures, 54 (18%) required mechanical ventilation, and 12 (4%) died. No clear benefit was found from use of plasmapheresis or plasmapheresis with glucocorticoids. 67 of the patients were treated with eculizumab, a monoclonal antibody directed against the complement cascade. No short term benefit was detected that could be attributed to this treatment. 52 patients in one centre that used a strategy of aggressive treatment with combined antibiotics had fewer seizures (2% v 15%, P = 0.03), fewer deaths (0% v 5%, p = 0.029), required no abdominal surgery, and excreted E coli for a shorter duration. CONCLUSIONS: Enterohaemorrhagic E coli induced haemolytic uraemic syndrome is a severe self limiting acute condition. Our findings question the benefit of eculizumab and of plasmapheresis with or without glucocorticoids. Patients with established haemolytic uraemic syndrome seemed to benefit from antibiotic treatment and this should be investigated in a controlled trial.
Assuntos
Antibacterianos/uso terapêutico , Anticorpos Monoclonais Humanizados/uso terapêutico , Surtos de Doenças , Escherichia coli Êntero-Hemorrágica , Infecções por Escherichia coli/terapia , Síndrome Hemolítico-Urêmica/terapia , Fatores Imunológicos/uso terapêutico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Antibacterianos/administração & dosagem , Anticorpos Monoclonais Humanizados/administração & dosagem , Estudos de Casos e Controles , Criança , Terapia Combinada , Diarreia/microbiologia , Progressão da Doença , Quimioterapia Combinada , Infecções por Escherichia coli/sangue , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/microbiologia , Feminino , Alemanha/epidemiologia , Glucocorticoides/administração & dosagem , Glucocorticoides/uso terapêutico , Síndrome Hemolítico-Urêmica/sangue , Síndrome Hemolítico-Urêmica/epidemiologia , Síndrome Hemolítico-Urêmica/microbiologia , Humanos , Fatores Imunológicos/administração & dosagem , Lactente , L-Lactato Desidrogenase/sangue , Masculino , Camundongos , Pessoa de Meia-Idade , Análise Multivariada , Plasmaferese/métodos , Contagem de Plaquetas , Diálise Renal/estatística & dados numéricos , Respiração Artificial/estatística & dados numéricos , Estudos Retrospectivos , Resultado do Tratamento , Adulto JovemRESUMO
Differences in the amount of fetal hemoglobin (HbF) that persists into adulthood affect the severity of sickle cell disease and the beta-thalassemia syndromes. Genetic association studies have identified sequence variants in the gene BCL11A that influence HbF levels. Here, we examine BCL11A as a potential regulator of HbF expression. The high-HbF BCL11A genotype is associated with reduced BCL11A expression. Moreover, abundant expression of full-length forms of BCL11A is developmentally restricted to adult erythroid cells. Down-regulation of BCL11A expression in primary adult erythroid cells leads to robust HbF expression. Consistent with a direct role of BCL11A in globin gene regulation, we find that BCL11A occupies several discrete sites in the beta-globin gene cluster. BCL11A emerges as a therapeutic target for reactivation of HbF in beta-hemoglobin disorders.
Assuntos
Proteínas de Transporte/genética , Células Eritroides/metabolismo , Hemoglobina Fetal/genética , Regulação da Expressão Gênica , Proteínas Nucleares/genética , Animais , Proteínas de Transporte/metabolismo , Linhagem Celular Tumoral , Células Cultivadas , Regulação para Baixo , Eritroblastos/metabolismo , Células Precursoras Eritroides/metabolismo , Eritropoese , Hemoglobina Fetal/biossíntese , Fator de Transcrição GATA1/metabolismo , Hemoglobinopatias/terapia , Histona Desacetilases/metabolismo , Humanos , Células K562 , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase , Camundongos , Família Multigênica , Proteínas Nucleares/metabolismo , Polimorfismo de Nucleotídeo Único , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Interferência de RNA , Proteínas Repressoras , Fatores de Transcrição/metabolismo , Transcrição Gênica , Globinas beta/genética , Globinas beta/metabolismo , gama-Globinas/genética , gama-Globinas/metabolismoRESUMO
Shwachman-Diamond Syndrome (SDS) is an autosomal recessive disorder characterized by bone marrow failure with significant predisposition to the development of poor prognosis myelodysplasia and leukemia, exocrine pancreatic failure and metaphyseal chondrodysplasia. Although the SBDS gene mutated in this disorder is highly conserved in Archaea and all eukaryotes, the function is unknown. To interpret the molecular consequences of SDS-associated mutations, we have solved the crystal structure of the Archaeoglobus fulgidus SBDS protein orthologue at a resolution of 1.9 angstroms, revealing a three domain architecture. The N-terminal (FYSH) domain is the most frequent target for disease mutations and contains a novel mixed alpha/beta-fold identical to the single domain yeast protein Yhr087wp that is implicated in RNA metabolism. The central domain consists of a three-helical bundle, whereas the C-terminal domain has a ferredoxin-like fold. By genetic complementation analysis of the essential Saccharomyces cerevisiae SBDS orthologue YLR022C, we demonstrate an essential role in vivo for the FYSH domain and the central three-helical bundle. We further show that the common SDS-related K62X truncation is non-functional. Most SDS-related missense mutations that alter surface epitopes do not impair YLR022C function, but mutations affecting residues buried in the hydrophobic core of the FYSH domain severely impair or abrogate complementation. These data are consistent with absence of homozygosity for the common K62X truncation mutation in individuals with SDS, indicating that the SDS disease phenotype is a consequence of expression of hypomorphic SBDS alleles and that complete loss of SBDS function is likely to be lethal.