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1.
Am J Hum Genet ; 104(4): 758-766, 2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30929739

RESUMO

By using exome sequencing and a gene matching approach, we identified de novo and inherited pathogenic variants in KDM3B in 14 unrelated individuals and three affected parents with varying degrees of intellectual disability (ID) or developmental delay (DD) and short stature. The individuals share additional phenotypic features that include feeding difficulties in infancy, joint hypermobility, and characteristic facial features such as a wide mouth, a pointed chin, long ears, and a low columella. Notably, two individuals developed cancer, acute myeloid leukemia and Hodgkin lymphoma, in childhood. KDM3B encodes for a histone demethylase and is involved in H3K9 demethylation, a crucial part of chromatin modification required for transcriptional regulation. We identified missense and truncating variants, suggesting that KDM3B haploinsufficiency is the underlying mechanism for this syndrome. By using a hybrid facial-recognition model, we show that individuals with a pathogenic variant in KDM3B have a facial gestalt, and that they show significant facial similarity compared to control individuals with ID. In conclusion, pathogenic variants in KDM3B cause a syndrome characterized by ID, short stature, and facial dysmorphism.

2.
Int J Cancer ; 145(4): 941-951, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30694527

RESUMO

Two percent of patients with Wilms tumors have a positive family history. In many of these cases the genetic cause remains unresolved. By applying germline exome sequencing in two families with two affected individuals with Wilms tumors, we identified truncating mutations in TRIM28. Subsequent mutational screening of germline and tumor DNA of 269 children affected by Wilms tumor was performed, and revealed seven additional individuals with germline truncating mutations, and one individual with a somatic truncating mutation in TRIM28. TRIM28 encodes a complex scaffold protein involved in many different processes, including gene silencing, DNA repair and maintenance of genomic integrity. Expression studies on mRNA and protein level showed reduction of TRIM28, confirming a loss-of-function effect of the mutations identified. The tumors showed an epithelial-type histology that stained negative for TRIM28 by immunohistochemistry. The tumors were bilateral in six patients, and 10/11 tumors are accompanied by perilobar nephrogenic rests. Exome sequencing on eight tumor DNA samples from six individuals showed loss-of-heterozygosity (LOH) of the TRIM28-locus by mitotic recombination in seven tumors, suggesting that TRIM28 functions as a tumor suppressor gene in Wilms tumor development. Additionally, the tumors showed very few mutations in known Wilms tumor driver genes, suggesting that loss of TRIM28 is the main driver of tumorigenesis. In conclusion, we identified heterozygous germline truncating mutations in TRIM28 in 11 children with mainly epithelial-type Wilms tumors, which become homozygous in tumor tissue. These data establish TRIM28 as a novel Wilms tumor predisposition gene, acting as a tumor suppressor gene by LOH.

3.
Clin Cancer Res ; 24(7): 1594-1603, 2018 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-29351919

RESUMO

Purpose: In many children with cancer and characteristics suggestive of a genetic predisposition syndrome, the genetic cause is still unknown. We studied the yield of pathogenic mutations by applying whole-exome sequencing on a selected cohort of children with cancer.Experimental Design: To identify mutations in known and novel cancer-predisposing genes, we performed trio-based whole-exome sequencing on germline DNA of 40 selected children and their parents. These children were diagnosed with cancer and had at least one of the following features: (1) intellectual disability and/or congenital anomalies, (2) multiple malignancies, (3) family history of cancer, or (4) an adult type of cancer. We first analyzed the sequence data for germline mutations in 146 known cancer-predisposing genes. If no causative mutation was found, the analysis was extended to the whole exome.Results: Four patients carried causative mutations in a known cancer-predisposing gene: TP53 and DICER1 (n = 3). In another 4 patients, exome sequencing revealed mutations causing syndromes that might have contributed to the malignancy (EP300-based Rubinstein-Taybi syndrome, ARID1A-based Coffin-Siris syndrome, ACTB-based Baraitser-Winter syndrome, and EZH2-based Weaver syndrome). In addition, we identified two genes, KDM3B and TYK2, which are possibly involved in genetic cancer predisposition.Conclusions: In our selected cohort of patients, pathogenic germline mutations causative or likely causative of the cancer phenotype were found in 8 patients, and two possible novel cancer-predisposing genes were identified. Therewith, our study shows the added value of sequencing beyond a cancer gene panel in selected patients, to recognize childhood cancer predisposition. Clin Cancer Res; 24(7); 1594-603. ©2018 AACR.

4.
Nature ; 553(7689): 511-514, 2018 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-29342136

RESUMO

Relapsed acute lymphoblastic leukaemia (ALL) is associated with resistance to chemotherapy and poor prognosis. Gain-of-function mutations in the 5'-nucleotidase, cytosolic II (NT5C2) gene induce resistance to 6-mercaptopurine and are selectively present in relapsed ALL. Yet, the mechanisms involved in NT5C2 mutation-driven clonal evolution during the initiation of leukaemia, disease progression and relapse remain unknown. Here we use a conditional-and-inducible leukaemia model to demonstrate that expression of NT5C2(R367Q), a highly prevalent relapsed-ALL NT5C2 mutation, induces resistance to chemotherapy with 6-mercaptopurine at the cost of impaired leukaemia cell growth and leukaemia-initiating cell activity. The loss-of-fitness phenotype of NT5C2+/R367Q mutant cells is associated with excess export of purines to the extracellular space and depletion of the intracellular purine-nucleotide pool. Consequently, blocking guanosine synthesis by inhibition of inosine-5'-monophosphate dehydrogenase (IMPDH) induced increased cytotoxicity against NT5C2-mutant leukaemia lymphoblasts. These results identify the fitness cost of NT5C2 mutation and resistance to chemotherapy as key evolutionary drivers that shape clonal evolution in relapsed ALL and support a role for IMPDH inhibition in the treatment of ALL.


Assuntos
5'-Nucleotidase/genética , 5'-Nucleotidase/metabolismo , Evolução Clonal , Resistencia a Medicamentos Antineoplásicos/genética , Mutação/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Animais , Proliferação de Células , Modelos Animais de Doenças , Feminino , Mutação com Ganho de Função/genética , Guanosina/biossíntese , Células HEK293 , Humanos , IMP Desidrogenase/antagonistas & inibidores , IMP Desidrogenase/metabolismo , Masculino , Mercaptopurina/farmacologia , Mercaptopurina/uso terapêutico , Camundongos , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Purinas/metabolismo , Receptor Notch1/metabolismo , Recidiva , Ensaios Antitumorais Modelo de Xenoenxerto
5.
Leuk Lymphoma ; 59(7): 1690-1699, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29058513

RESUMO

Pathogenic mutations in relapse-associated genes in pediatric acute lymphoblastic leukemia may improve risk stratification when detected at subclonal levels at primary diagnosis. However, to detect subclonal mutations upfront, a deep-sequencing approach with high specificity and sensitivity is required. Here, we performed a proof-of-principle study to detect low-level mosaic RAS pathway mutations by deep sequencing using random tagging-based single molecule Molecular Inversion Probes (smMIPs). The smMIP-based approach could sensitively detect variants with allele frequency as low as 0.4%, which could all be confirmed by other techniques. In comparison, with standard deep-sequencing techniques we reached a detection threshold of only 2.5%, which hampered detection of seven low-level mosaic mutations representing 24% of all detected mutations. We conclude that smMIP-based deep-sequencing outperforms standard deep-sequencing techniques by showing lower background noise and high specificity, and is the preferred technology for detecting mutations upfront, particularly in genes in which mutations show limited clustering in hotspots.

6.
Haematologica ; 102(3): 541-551, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27979924

RESUMO

Deletions and mutations affecting lymphoid transcription factor IKZF1 (IKAROS) are associated with an increased relapse risk and poor outcome in B-cell precursor acute lymphoblastic leukemia. However, additional genetic events may either enhance or negate the effects of IKZF1 deletions on prognosis. In a large discovery cohort of 533 childhood B-cell precursor acute lymphoblastic leukemia patients, we observed that single-copy losses of BTG1 were significantly enriched in IKZF1-deleted B-cell precursor acute lymphoblastic leukemia (P=0.007). While BTG1 deletions alone had no impact on prognosis, the combined presence of BTG1 and IKZF1 deletions was associated with a significantly lower 5-year event-free survival (P=0.0003) and a higher 5-year cumulative incidence of relapse (P=0.005), when compared with IKZF1-deleted cases without BTG1 aberrations. In contrast, other copy number losses commonly observed in B-cell precursor acute lymphoblastic leukemia, such as CDKN2A/B, PAX5, EBF1 or RB1, did not affect the outcome of IKZF1-deleted acute lymphoblastic leukemia patients. To establish whether the combined loss of IKZF1 and BTG1 function cooperate in leukemogenesis, Btg1-deficient mice were crossed onto an Ikzf1 heterozygous background. We observed that loss of Btg1 increased the tumor incidence of Ikzf1+/- mice in a dose-dependent manner. Moreover, murine B cells deficient for Btg1 and Ikzf1+/- displayed increased resistance to glucocorticoids, but not to other chemotherapeutic drugs. Together, our results identify BTG1 as a tumor suppressor in leukemia that, when deleted, strongly enhances the risk of relapse in IKZF1-deleted B-cell precursor acute lymphoblastic leukemia, and augments the glucocorticoid resistance phenotype mediated by the loss of IKZF1 function.


Assuntos
Transformação Celular Neoplásica/genética , Epistasia Genética , Fator de Transcrição Ikaros/genética , Proteínas de Neoplasias/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Proteínas Supressoras de Tumor/genética , Adolescente , Animais , Biomarcadores Tumorais , Transformação Celular Neoplásica/metabolismo , Criança , Pré-Escolar , Modelos Animais de Doenças , Resistencia a Medicamentos Antineoplásicos/genética , Feminino , Deleção de Genes , Predisposição Genética para Doença , Humanos , Fator de Transcrição Ikaros/metabolismo , Masculino , Camundongos , Camundongos Knockout , Proteínas de Neoplasias/metabolismo , Avaliação de Resultados da Assistência ao Paciente , Leucemia-Linfoma Linfoblástico de Células Precursoras B/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras B/mortalidade , Prognóstico , Recidiva , Proteínas Supressoras de Tumor/metabolismo
8.
Nat Genet ; 48(12): 1481-1489, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27776115

RESUMO

Chromosomal rearrangements deregulating hematopoietic transcription factors are common in acute lymphoblastic leukemia (ALL). Here we show that deregulation of the homeobox transcription factor gene DUX4 and the ETS transcription factor gene ERG is a hallmark of a subtype of B-progenitor ALL that comprises up to 7% of B-ALL. DUX4 rearrangement and overexpression was present in all cases and was accompanied by transcriptional deregulation of ERG, expression of a novel ERG isoform, ERGalt, and frequent ERG deletion. ERGalt uses a non-canonical first exon whose transcription was initiated by DUX4 binding. ERGalt retains the DNA-binding and transactivation domains of ERG, but it inhibits wild-type ERG transcriptional activity and is transforming. These results illustrate a unique paradigm of transcription factor deregulation in leukemia in which DUX4 deregulation results in loss of function of ERG, either by deletion or induced expression of an isoform that is a dominant-negative inhibitor of wild-type ERG function.


Assuntos
Transformação Celular Neoplásica/genética , Deleção de Genes , Regulação Neoplásica da Expressão Gênica , Rearranjo Gênico , Proteínas de Homeodomínio/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Adolescente , Adulto , Transformação Celular Neoplásica/patologia , Perfilação da Expressão Gênica , Humanos , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Isoformas de Proteínas , Regulador Transcricional ERG/genética , Adulto Jovem
9.
Eur J Med Genet ; 59(3): 116-25, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26825391

RESUMO

Genetic predisposition for childhood cancer is under diagnosed. Identifying these patients may lead to therapy adjustments in case of syndrome-related increased toxicity or resistant disease and syndrome-specific screening programs may lead to early detection of a further independent malignancy. Cancer surveillance might also be warranted for affected relatives and detection of a genetic mutation can allow for reproductive counseling. Here we present an easy-to-use selection tool, based on a systematic review of pediatric cancer predisposing syndromes, to identify patients who may benefit from genetic counseling. The selection tool involves five questions concerning family history, the type of malignancy, multiple primary malignancies, specific features and excessive toxicity, which results in the selection of those patients that may benefit from referral to a clinical geneticist.


Assuntos
Predisposição Genética para Doença , Neoplasias/epidemiologia , Neoplasias/genética , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/epidemiologia , Anormalidades Múltiplas/genética , Fatores Etários , Criança , Pré-Escolar , Estudos de Associação Genética , Humanos , Neoplasias/diagnóstico , Fenótipo , Vigilância da População/métodos , Risco , Síndrome
10.
J Clin Lab Anal ; 30(5): 431-6, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26365003

RESUMO

BACKGROUND: Isolated polycystic liver disease (ADPLD) is an autosomal dominant Mendelian disorder. Heterozygous PRKCSH (where PRKCSH is protein kinase C substrate 80K-H (80 kDa protein, heavy chain; MIM*177060) mutations are the most frequent cause. Routine molecular testing using Sanger sequencing identifies pathogenic variants in the PRKCSH (15%) and SEC63 (where SEC63 is Saccharomyces cerevisiae homolog 63 (MIM*608648); 6%) genes, but about approximately 80% of patients meeting the clinical ADPLD criteria carry no PRKCSH or SEC63 mutation. Cyst tissue often shows somatic deletions with loss of heterozygosity that was recently recognized as a general mechanism in ADPLD. We hypothesized that germline deletions in the PRKCSH gene may be responsible for hepatic cystogenesis in a significant number of mutation-negative ADPLD patients. METHODS: In this study, we designed a multiplex ligation-dependent probe amplification (MLPA) assay to screen for deletions of PRKCSH exons. Genomic DNA from 60 patients with an ADPLD phenotype was included. RESULTS: MLPA analysis detected no exon deletions in mutation-negative ADPLD patients. CONCLUSION: Large copy number variations on germline level are not present in patients with a clinical diagnosis of ADPLD. MLPA analysis of the PRKCSH gene should not be considered as a diagnostic method to explain hepatic cystogenesis.


Assuntos
Cistos/genética , Glucosidases/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Hepatopatias/genética , Deleção de Sequência/genética , Adulto , Idoso , Feminino , Humanos , Masculino , Proteínas de Membrana/genética , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase Multiplex/métodos , Estudos Retrospectivos
13.
Nat Genet ; 46(2): 96-8, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24473322

RESUMO

Genomic aberrations affecting genes in B cell differentiation are hallmarks of B-precursor acute lymphoblastic leukemia (ALL). A new whole-genome sequencing study of ETV6-RUNX1-positive ALL has now identified RAG-mediated recombination, which specifically targets genes and regulatory elements active during B cell differentiation, as the underlying mechanism.


Assuntos
Subunidade alfa 2 de Fator de Ligação ao Core/genética , Regulação Neoplásica da Expressão Gênica/genética , Rearranjo Gênico/genética , Variação Genética , Proteínas de Homeodomínio/genética , Proteínas de Fusão Oncogênica/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Recombinação Genética/genética , Humanos
14.
Nat Genet ; 45(10): 1226-1231, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24013638

RESUMO

Somatic alterations of the lymphoid transcription factor gene PAX5 (also known as BSAP) are a hallmark of B cell precursor acute lymphoblastic leukemia (B-ALL), but inherited mutations of PAX5 have not previously been described. Here we report a new heterozygous germline variant, c.547G>A (p.Gly183Ser), affecting the octapeptide domain of PAX5 that was found to segregate with disease in two unrelated kindreds with autosomal dominant B-ALL. Leukemic cells from all affected individuals in both families exhibited 9p deletion, with loss of heterozygosity and retention of the mutant PAX5 allele at 9p13. Two additional sporadic ALL cases with 9p loss harbored somatic PAX5 substitutions affecting Gly183. Functional and gene expression analysis of the PAX5 mutation demonstrated that it had significantly reduced transcriptional activity. These data extend the role of PAX5 alterations in the pathogenesis of pre-B cell ALL and implicate PAX5 in a new syndrome of susceptibility to pre-B cell neoplasia.


Assuntos
Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Fator de Transcrição PAX5/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Humanos , Polimorfismo de Nucleotídeo Único
15.
Blood ; 122(15): 2622-9, 2013 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-23974192

RESUMO

Most relapses in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are not predicted using current prognostic features. Here, we determined the co-occurrence and independent prognostic relevance of 3 recently identified prognostic features: BCR-ABL1-like gene signature, deletions in IKZF1, and high CRLF2 messenger RNA expression (CRLF2-high). These features were determined in 4 trials representing 1128 children with ALL: DCOG ALL-8, ALL9, ALL10, and Cooperative ALL (COALL)-97/03. BCR-ABL1-like, IKZF1-deleted, and CRLF2-high cases constitute 33.7% of BCR-ABL1-negative, MLL wild-type BCP-ALL cases, of which BCR-ABL1-like and IKZF1 deletion (co)occurred most frequently. Higher cumulative incidence of relapse was found for BCR-ABL1-like and IKZF1-deleted, but not CRLF2-high, cases relative to remaining BCP-ALL cases, reflecting the observations in each of the cohorts analyzed separately. No relapses occurred among cases with CRLF2-high as single feature, whereas 62.9% of all relapses in BCR-ABL1-negative, MLL wild-type BCP-ALL occurred in cases with BCR-ABL1-like signature and/or IKZF1 deletion. Both the BCR-ABL1-like signature and IKZF1 deletions were prognostic features independent of conventional prognostic markers in a multivariate model, and both remained prognostic among cases with intermediate minimal residual disease. The BCR-ABL1-like signature and an IKZF1 deletion, but not CRLF2-high, are prognostic factors and are clinically of importance to identify high-risk patients who require more intensive and/or alternative therapies.


Assuntos
Proteínas de Fusão bcr-abl/genética , Fator de Transcrição Ikaros/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/epidemiologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Receptores de Citocinas/genética , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Incidência , Lactente , Masculino , Leucemia-Linfoma Linfoblástico de Células Precursoras B/epidemiologia , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Valor Preditivo dos Testes , Prognóstico , Recidiva , Fatores de Risco
16.
PLoS Genet ; 8(2): e1002533, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22359517

RESUMO

Recurrent submicroscopic deletions in genes affecting key cellular pathways are a hallmark of pediatric acute lymphoblastic leukemia (ALL). To gain more insight into the mechanism underlying these deletions, we have studied the occurrence and nature of abnormalities in one of these genes, the B-cell translocation gene 1 (BTG1), in a large cohort of pediatric ALL cases. BTG1 was found to be exclusively affected by genomic deletions, which were detected in 65 out of 722 B-cell precursor ALL (BCP-ALL) patient samples (9%), but not in 109 T-ALL cases. Eight different deletion sizes were identified, which all clustered at the telomeric site in a hotspot region within the second (and last) exon of the BTG1 gene, resulting in the expression of truncated BTG1 read-through transcripts. The presence of V(D)J recombination signal sequences at both sites of virtually all deletions strongly suggests illegitimate RAG1/RAG2-mediated recombination as the responsible mechanism. Moreover, high levels of histone H3 lysine 4 trimethylation (H3K4me3), which is known to tether the RAG enzyme complex to DNA, were found within the BTG1 gene body in BCP-ALL cells, but not T-ALL cells. BTG1 deletions were rarely found in hyperdiploid BCP-ALLs, but were predominant in other cytogenetic subgroups, including the ETV6-RUNX1 and BCR-ABL1 positive BCP-ALL subgroups. Through sensitive PCR-based screening, we identified multiple additional BTG1 deletions at the subclonal level in BCP-ALL, with equal cytogenetic distribution which, in some cases, grew out into the major clone at relapse. Taken together, our results indicate that BTG1 deletions may act as "drivers" of leukemogenesis in specific BCP-ALL subgroups, in which they can arise independently in multiple subclones at sites that are prone to aberrant RAG1/RAG2-mediated recombination events. These findings provide further evidence for a complex and multiclonal evolution of ALL.


Assuntos
Evolução Clonal , Deleção de Genes , Proteínas de Neoplasias/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Doença Aguda , Criança , Humanos , Leucemia-Linfoma Linfoblástico de Células Precursoras B/patologia , Células Precursoras de Linfócitos B/metabolismo , Células Precursoras de Linfócitos B/patologia
17.
Genes Chromosomes Cancer ; 50(12): 969-81, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21882283

RESUMO

In acute lymphoblastic leukemia (ALL) specific genomic abnormalities provide important clinical information. In most routine clinical diagnostic laboratories conventional karyotyping, in conjunction with targeted screens using e.g., fluorescence in situ hybridization (FISH), is currently considered as the gold standard to detect such aberrations. Conventional karyotyping, however, is limited in its resolution and yield, thus hampering the genetic diagnosis of ALL. We explored whether microarray-based genomic profiling would be feasible as an alternative strategy in a routine clinical diagnostic setting. To this end, we compared conventional karyotypes with microarray-deduced copy number aberration (CNA) karyotypes in 60 ALL cases. Microarray-based genomic profiling resulted in a CNA detection rate of 90%, whereas for conventional karyotyping this was 61%. In addition, many small (< 5 Mb) genetic lesions were encountered, frequently harboring clinically relevant ALL-related genes such as CDKN2A/B, ETV6, PAX5, and IKZF1. From our data we conclude that microarray-based genomic profiling serves as a robust tool in the genetic diagnosis of ALL, outreaching conventional karyotyping in CNA detection both in terms of sensitivity and specificity. We also propose a practical workflow for a comprehensive and objective interpretation of CNAs obtained through microarray-based genomic profiling, thereby facilitating its application in a routine clinical diagnostic setting.


Assuntos
Análise de Sequência com Séries de Oligonucleotídeos/métodos , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Criança , Aberrações Cromossômicas , Impressões Digitais de DNA/métodos , Feminino , Dosagem de Genes , Humanos , Hibridização in Situ Fluorescente/métodos , Cariotipagem/métodos , Masculino , Polimorfismo de Nucleotídeo Único , Sensibilidade e Especificidade
18.
Gastroenterology ; 141(6): 2056-2063.e2, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21856269

RESUMO

BACKGROUND & AIMS: Heterozygous germline mutations in PRKCSH cause autosomal dominant polycystic liver disease (PCLD), but it is not clear how they lead to cyst formation. We investigated whether mutations in cyst epithelial cells and corresponding loss of the PRKCSH gene product (hepatocystin) contributed to cyst development. METHODS: Liver cyst material was collected through laparoscopic cyst fenestration from 8 patients with PCLD who had a heterozygous germline mutation in PRKCSH. Tissue sections from 71 cysts (2-14 per patient) were obtained for hepatocystin staining and mutation analysis. Cyst epithelium was acquired using laser microdissection; DNA was isolated and analyzed for loss of heterozygosity (LOH) and somatic mutations using restriction analysis and sequencing. Common single nucleotide polymorphisms (SNPs) in a 70-kilobase region surrounding the germline mutation were used to determine variations in the genomic region with LOH. RESULTS: The wild-type allele of PRKCSH was lost (LOH) in 76% of cysts (54/71). Hepatocystin was not detected in cyst epithelia with LOH, whereas heterozygous cysts still expressed hepatocystin. The variation observed in the LOH region analysis indicates that cysts develop independently. We also detected somatic mutations in PRKCSH in 17% (2/12) of the cysts without LOH. Trans-heterozygous mutations in SEC63 were not observed. CONCLUSIONS: Among patients with PCLD who have a heterozygous germline mutation in PRKCSH, we found secondary, somatic mutations (second hits) in more than 76% of the liver cyst epithelia. PCLD is recessive at the cellular level, and loss of functional PRKCSH is an important step in cystogenesis.


Assuntos
Cistos/genética , Glucosidases/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Hepatopatias/genética , Perda de Heterozigosidade , Mutação/genética , Adulto , Cistos/fisiopatologia , Análise Mutacional de DNA , Feminino , Mutação em Linhagem Germinativa , Humanos , Hepatopatias/fisiopatologia , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único
19.
J Clin Oncol ; 29(12): 1643-9, 2011 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-21357790

RESUMO

PURPOSE: Relapse of childhood T-cell acute lymphoblastic leukemia (T-ALL) often occurs during treatment, but in some cases, leukemia re-emerges off therapy. On the basis of previous analyses of T-cell receptor (TCR) gene rearrangement patterns, we hypothesized that some late recurrences of T-ALL might in fact represent second leukemias. PATIENTS AND METHODS: In 22 patients with T-ALL who had late relapses (at least 2.5 years from diagnosis), we studied TCR gene rearrangement status at first and second presentation, NOTCH1 gene mutations, and the presence of the SIL-TAL1 gene fusion. We performed genome-wide copy number and homozygosity analysis by using oligonucleotide- and single nucleotide polymorphism (SNP) -based arrays. RESULTS: We found evidence of a common clonal origin between diagnosis and relapse in 14 patients (64%). This was based on concordant TCR gene rearrangements (12 patients) or concordant genetic aberrations, as revealed by genome-wide copy number analysis (two patients). In the remaining eight patients (36%), TCR gene rearrangement sequences had completely changed between diagnosis and relapse, and gene copy number analysis showed markedly different patterns of genomic aberrations, suggesting a second T-ALL rather than a resurgence of the original clone. Moreover, NOTCH1 mutation patterns were different at diagnosis and relapse in five of these eight patients. In one patient with a second T-ALL, SNP analysis revealed a germline del(11)(p12;p13), a known recurrent aberration in T-ALL. CONCLUSION: More than one third of late T-ALL recurrences are, in fact, second leukemias. Germline genetic abnormalities might contribute to the susceptibility of some patients to develop T-ALL.


Assuntos
Regulação Leucêmica da Expressão Gênica , Segunda Neoplasia Primária/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Adolescente , Criança , Pré-Escolar , Europa (Continente) , Feminino , Dosagem de Genes , Perfilação da Expressão Gênica/métodos , Rearranjo Gênico do Linfócito T , Genes Codificadores dos Receptores de Linfócitos T/genética , Predisposição Genética para Doença , Homozigoto , Humanos , Masculino , Mutação , Segunda Neoplasia Primária/imunologia , Segunda Neoplasia Primária/patologia , New South Wales , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas de Fusão Oncogênica/genética , Fenótipo , Polimorfismo de Nucleotídeo Único , Leucemia-Linfoma Linfoblástico de Células T Precursoras/imunologia , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patologia , Leucemia-Linfoma Linfoblástico de Células T Precursoras/terapia , Receptor Notch1/genética , Recidiva , Tennessee , Fatores de Tempo , Resultado do Tratamento
20.
Blood ; 115(23): 4810-9, 2010 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-20354172

RESUMO

Resistance to glucocorticoids (GCs) is a major clinical problem in the treatment of acute lymphoblastic leukemia (ALL), but the underlying mechanisms are not well understood. Although mutations in the glucocorticoid receptor (GR) gene can give rise to therapy resistance in vitro, acquired somatic mutations in the GR are rarely encountered in patients. Here we report that the protein encoded by the BTG1 gene, which is frequently deleted in (pediatric) ALL, is a key determinant of GC responsiveness. Using RNA interference, we show that loss of BTG1 expression causes GC resistance both by decimating GR expression and by controlling GR-mediated transcription. Conversely, reexpression of BTG1 restores GC sensitivity by potentiating GC-induced GR expression, a phenomenon known as GR autoinduction. In addition, the arginine methyltransferase PRMT1, a BTG1-binding partner and transcriptional coactivator, is recruited to the GR gene promoter in a BTG1-dependent manner. These results implicate the BTG1/PRMT1 complex in GR-mediated gene expression and reveal that deregulation of a nuclear receptor coactivator complex can give rise to GC resistance. Further characterization of this complex as part of the GR regulatory circuitry could offer novel opportunities for improving the efficacy of GC-based therapies in ALL and other hematologic malignancies.


Assuntos
Resistencia a Medicamentos Antineoplásicos , Regulação Leucêmica da Expressão Gênica , Proteínas de Neoplasias/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Receptores de Glucocorticoides/biossíntese , Linhagem Celular Tumoral , Feminino , Deleção de Genes , Glucocorticoides/efeitos adversos , Glucocorticoides/farmacologia , Glucocorticoides/uso terapêutico , Humanos , Masculino , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Proteínas de Neoplasias/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Regiões Promotoras Genéticas/genética , Proteína-Arginina N-Metiltransferases/genética , Proteína-Arginina N-Metiltransferases/metabolismo , Interferência de RNA , Receptores de Glucocorticoides/agonistas , Receptores de Glucocorticoides/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transcrição Genética/efeitos dos fármacos , Transcrição Genética/genética
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