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2.
Artigo em Inglês | MEDLINE | ID: mdl-31677197

RESUMO

T-cell prolymphocytic leukemia (T-PLL) is an aggressive tumor with leukemic presentation of mature T-lymphocytes. Here, we aimed at characterizing the initial events in the molecular pathogenesis of T-PLL and particularly, at determining the point in T-cell differentiation when the hallmark oncogenic events, that is, inv(14)(q11q32)/t(14;14)(q11;q32) and t(X;14)(q28;q11) occur. To this end, we mined whole genome and transcriptome sequencing data of 17 and 11 T-PLL cases, respectively. Mapping of the 14q32.1 locus breakpoints identified only TCL1A, which was moreover significantly overexpressed in T-PLL as compared to benign CD4+ and CD8+ T-cells, as the only common oncogenic target of aberrations. In cases with t(14;14), the breakpoints mapped telomeric and in cases with inv(14) centromeric or in the 3'-untranslated region of TCL1A. Regarding the T-cell receptor alpha (TRA) locus-TCL1A breakpoint junctions, all 17 breakpoints involved recombination signal sequences and 15 junctions contained nontemplated (N-) nucleotides. All T-PLL cases studied carried in-frame TRA rearrangements on the intact allele, which skewed significantly toward usage of distal/central TRAV/TRAJ gene segments as compared to the illegitimate TRA rearrangements. Our findings suggest that the oncogenic TRA-TCL1A/MTCP1 rearrangements in T-PLL occur during opening of the TRA locus, that is, during the progression from CD4+ immature single positive to early double positive thymocyte stage, just before physiologic TCL1A expression is silenced. The cell carrying such an oncogenic event continues maturation and rearranges the second TRA allele to achieve a functional T-cell receptor. Thereafter, it switches off RAG and DNTT expression in line with the mature T-cell phenotype at presentation of T-PLL.

3.
Haematologica ; 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31601689

RESUMO

The BCL-2 specific inhibitor, venetoclax/ABT-199 has exhibited remarkable clinical activity in nearly all cases of chronic lymphocytic leukemia. In contrast, responses are usually much less in diffuse large B-cell lymphoma, despite high level expression of BCL-2 in over 40% of cases, indicating that co-expression of related anti-apoptotic BCL-2 family proteins may limit activity. We have investigated the roles of the BCL-2 proteins in diffuse large B-cell lymphoma cells using a panel of specific BCL-2 Homology 3 mimetics and identified subgroups of diffuse large B-cell lymphoma cells that exhibited marked and specific dependency on either BCL-2, BCL-XL or MCL-1 for survival. Dependency was associated with a sequestration of the pro-apoptotic proteins BIM, BAX and BAK selectively by the specific anti-apoptotic BCL-2 protein that was important for cellular survival. Sensitivity to BCL-2 Homology 3 mimetics was independent of genetic alterations involving the BCL-2 family and only partially correlated with protein expression levels. Treatment with ABT-199 displaced BAX and BIM from BCL-2, leading subsequently to BAK activation and apoptosis. In contrast, apoptosis induced by inhibiting BCL-XL with A1331852 was associated with a displacement of both BAX and BAK from BCL-XL and occurred independently of BIM. Finally, the MCL-1 inhibitor S63845 induced mainly BAX-dependent apoptosis mediated by a displacement of BAK, BIM and NOXA from MCL-1. In conclusion, our study indicates that in diffuse large B-cell lymphoma, the heterogeneous response to BCL-2 Homology 3 mimetics is mediated by selective interactions between BAX, BAK and anti-apoptotic BCL-2 proteins.

6.
J Cell Mol Med ; 23(1): 340-348, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30353642

RESUMO

CUDC-907, a dual PI3K/HDAC inhibitor, has been proposed to have therapeutic potential in hematopoietic malignancies. However, the molecular mechanisms of its effects in chronic lymphocytic leukaemia (CLL) remain elusive. We show that CLL cells are sensitive to CUDC-907, even under conditions similar to the protective microenvironment of proliferation centres. CUDC-907 inhibited PI3K/AKT and HDAC activity, as expected, but also suppressed RAF/MEK/ERK and STAT3 signalling and reduced the expression of anti-apoptotic BCL-2 family proteins BCL-2, BCL-xL, and MCL-1. Moreover, CUDC-907 downregulated cytokines BAFF and APRIL and their receptors BAFFR, TACI, and BCMA, thus blocking BAFF-induced NF-κB signalling. T cell chemokines CCL3/4/17/22 and phosphorylation of CXCR4 were also reduced by CUDC-907. These data indicated that CUDC-907 abrogates different protective signals and suggested that it might sensitize CLL cells to other drugs. Indeed, combinations of low concentrations of CUDC-907 with inhibitors of BCL2, BTK, or the NF-κB pathway showed a potent synergistic effect. Our data indicate that, apart from its known functions, CUDC-907 blocks multiple pro-survival pathways to overcome microenvironment protection in CLL cells. This provides a rationale to evaluate the clinical relevance of CUDC-907 in combination therapies with other targeted inhibitors.

7.
Cancers (Basel) ; 10(4)2018 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-29690649

RESUMO

Bruton's tyrosine kinase (BTK) is a key regulator of the B-cell receptor signaling pathway, and aberrant B-cell receptor (BCR) signaling has been implicated in the survival of malignant B-cells. However, responses of the diffuse large B-cell lymphoma (DLBCL) to inhibitors of BTK (BTKi) are infrequent, highlighting the need to identify mechanisms of resistance to BTKi as well as predictive biomarkers. We investigated the response to the selective BTKi, tirabrutinib, in a panel of 64 hematopoietic cell lines. Notably, only six cell lines were found to be sensitive. Although activated B-cell type DLBCL cells were most sensitive amongst all cell types studied, sensitivity to BTKi did not correlate with the presence of activating mutations in the BCR pathway. To improve efficacy of tirabrutinib, we investigated combination strategies with 43 drugs inhibiting 34 targets in six DLBCL cell lines. Based on the results, an activated B-cell-like (ABC)-DLBCL cell line, TMD8, was the most sensitive cell line to those combinations, as well as tirabrutinib monotherapy. Furthermore, tirabrutinib in combination with idelalisib, palbociclib, or trametinib was more effective in TMD8 with acquired resistance to tirabrutinib than in the parental cells. These targeted agents might be usefully combined with tirabrutinib in the treatment of ABC-DLBCL.

9.
Blood Cancer J ; 9(1): 1, 2018 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-30602759

RESUMO

The clustering of different types of B-cell malignancies in families raises the possibility of shared aetiology. To examine this, we performed cross-trait linkage disequilibrium (LD)-score regression of multiple myeloma (MM) and chronic lymphocytic leukaemia (CLL) genome-wide association study (GWAS) data sets, totalling 11,734 cases and 29,468 controls. A significant genetic correlation between these two B-cell malignancies was shown (Rg = 0.4, P = 0.0046). Furthermore, four of the 45 known CLL risk loci were shown to associate with MM risk and five of the 23 known MM risk loci associate with CLL risk. By integrating eQTL, Hi-C and ChIP-seq data, we show that these pleiotropic risk loci are enriched for B-cell regulatory elements and implicate B-cell developmental genes. These data identify shared biological pathways influencing the development of CLL and, MM and further our understanding of the aetiological basis of these B-cell malignancies.


Assuntos
Estudos de Associação Genética , Predisposição Genética para Doença , Leucemia Linfocítica Crônica de Células B/genética , Mieloma Múltiplo/genética , Alelos , Estudos de Casos e Controles , Bases de Dados Genéticas , Ligação Genética , Estudo de Associação Genômica Ampla , Humanos , Desequilíbrio de Ligação , Especificidade de Órgãos/genética , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas
12.
Nat Commun ; 8: 14175, 2017 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-28165464

RESUMO

Several chronic lymphocytic leukaemia (CLL) susceptibility loci have been reported; however, much of the heritable risk remains unidentified. Here we perform a meta-analysis of six genome-wide association studies, imputed using a merged reference panel of 1,000 Genomes and UK10K data, totalling 6,200 cases and 17,598 controls after replication. We identify nine risk loci at 1p36.11 (rs34676223, P=5.04 × 10-13), 1q42.13 (rs41271473, P=1.06 × 10-10), 4q24 (rs71597109, P=1.37 × 10-10), 4q35.1 (rs57214277, P=3.69 × 10-8), 6p21.31 (rs3800461, P=1.97 × 10-8), 11q23.2 (rs61904987, P=2.64 × 10-11), 18q21.1 (rs1036935, P=3.27 × 10-8), 19p13.3 (rs7254272, P=4.67 × 10-8) and 22q13.33 (rs140522, P=2.70 × 10-9). These new and established risk loci map to areas of active chromatin and show an over-representation of transcription factor binding for the key determinants of B-cell development and immune response.


Assuntos
Formação de Anticorpos/genética , Cromossomos Humanos/genética , Predisposição Genética para Doença , Leucemia Linfocítica Crônica de Células B/genética , Adulto , Linfócitos B/imunologia , Linfócitos B/fisiologia , Estudos de Casos e Controles , Mapeamento Cromossômico , Feminino , Estudo de Associação Genômica Ampla , Humanos , Leucemia Linfocítica Crônica de Células B/imunologia , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Adulto Jovem
13.
Cancer Res ; 76(21): 6311-6319, 2016 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-27634759

RESUMO

Chronic lymphocytic leukemia (CLL) cells multiply and become more resistant to immunochemotherapy in "proliferation centers" within tissues, whereas apoptosis occurs in the periphery. Various models recapitulate these microenvironments in vitro, such as stimulation with CD154 and IL4. Using this system, we observed a 30- to 40-fold induction of wild-type p53 protein in 50 distinct human CLL specimens tested, without the induction of either cell-cycle arrest or apoptosis. In contrast, the mRNA levels for p53 did not increase, indicating that its elevation occurred posttranscriptionally. Mechanistic investigations revealed that under the conditions studied, p53 was phosphorylated on residues associated with p53 activation and increased half-life. However, p53 protein induced in this manner could transcriptionally activate only a subset of target genes. The addition of a DNA-damaging agent further upregulated p53 protein levels, which led to apoptosis. p53 induction relied on the increase in intracellular reactive oxygen species observed after CD154 and IL4 stimulation. We propose that chronic oxidative stress is a characteristic of the microenvironment in B-cell "proliferation centers" in CLL that are capable of elevating the basal expression of p53, but to levels below the threshold needed to induce arrest or apoptosis. Our findings suggest that reactivation of the full transcriptional activities of p53 in proliferating CLL cells may offer a possible therapeutic strategy. Cancer Res; 76(21); 6311-9. ©2016 AACR.


Assuntos
Leucemia Linfocítica Crônica de Células B/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteína Supressora de Tumor p53/fisiologia , Ligante de CD40/farmacologia , Humanos , Interleucina-4/farmacologia , Leucemia Linfocítica Crônica de Células B/patologia , Ativação Transcricional , Células Tumorais Cultivadas , Regulação para Cima
14.
Blood ; 128(19): 2319-2326, 2016 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-27528712

RESUMO

Chronic lymphocytic leukemia (CLL) can be familial; however, thus far no rare germ line disruptive alleles for CLL have been identified. We performed whole-exome sequencing of 66 CLL families, identifying 4 families where loss-of-function mutations in protection of telomeres 1 (POT1) co-segregated with CLL. The p.Tyr36Cys mutation is predicted to disrupt the interaction between POT1 and the telomeric overhang. The c.1164-1G>A splice-site, p.Gln358SerfsTer13 frameshift, and p.Gln376Arg missense mutations are likely to impact the interaction between POT1 and adrenocortical dysplasia homolog (ACD), which is a part of the telomere-capping shelterin complex. We also identified mutations in ACD (c.752-2A>C) and another shelterin component, telomeric repeat binding factor 2, interacting protein (p.Ala104Pro and p.Arg133Gln), in 3 CLL families. In a complementary analysis of 1083 cases and 5854 controls, the POT1 p.Gln376Arg variant, which has a global minor allele frequency of 0.0005, conferred a 3.61-fold increased risk of CLL (P = .009). This study further highlights telomere dysregulation as a key process in CLL development.


Assuntos
Mutação em Linhagem Germinativa/genética , Leucemia Linfocítica Crônica de Células B/genética , Proteínas de Ligação a Telômeros/genética , Sequência de Aminoácidos , Feminino , Humanos , Masculino , Linhagem , Sítios de Splice de RNA/genética , Homeostase do Telômero , Proteínas de Ligação a Telômeros/química
15.
Br J Haematol ; 175(4): 641-651, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27469405

RESUMO

Dinaciclib is a cyclin-dependent kinase inhibitor with clinical potential in different cancers, including chronic lymphocytic leukaemia (CLL). In order to better understand its cytotoxic action, we characterized its effects on signalling pathways important for the survival of CLL cells. We found that dinaciclib induced apoptosis through the activation of caspases 8 and 9, which was independent of the presence of cytokines to mimic the environment of proliferation centres or IGVH mutation status. Moreover, treatment with dinaciclib led to the inhibition of oncogenic pathways normally activated in stimulated CLL cells, such as STAT3, NF-κB, p38, PI3K/AKT and RAF/MEK/ERK. Dinaciclib was also able to block the expression of anti-apoptotic proteins of the BCL2 family such as MCL1 and BCL-xL (also termed BCL2L1). Finally, we showed that low concentrations of dinaciclib enhanced cell sensitivity to ibrutinib and the BCL2 inhibitor ABT-199, two drugs with known effects on CLL. Taken together, our data show that dinaciclib targets multiple pro-survival signalling pathways in CLL, which provides a mechanistic explanation for its potent induction of apoptosis. They also support a therapeutic application of cyclin-dependent kinase inhibitors in CLL in combination with other relevant targeted therapies.


Assuntos
Antineoplásicos/uso terapêutico , Compostos Bicíclicos Heterocíclicos com Pontes/uso terapêutico , Quinases Ciclina-Dependentes/antagonistas & inibidores , Leucemia Linfocítica Crônica de Células B/tratamento farmacológico , Leucemia Linfocítica Crônica de Células B/metabolismo , Inibidores de Proteínas Quinases/uso terapêutico , Compostos de Piridínio/uso terapêutico , Transdução de Sinais/efeitos dos fármacos , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Caspases/metabolismo , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Humanos , Inibidores de Proteínas Quinases/farmacologia , Compostos de Piridínio/farmacologia
16.
Sci Rep ; 6: 22730, 2016 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-26947392

RESUMO

Primary effusion lymphomas (PEL) are associated with human herpesvirus-8 (HHV-8) and usually occur in immunocompromised individuals. However, there are numerous reports of HHV-8-unrelated PEL-like lymphomas with unknown aetiology. Here we characterize an HHV-8-unrelated PEL-like lymphoma in an elderly woman who was negative for human immunodeficiency viruses 1 and 2, and hepatitis B and C. The woman was, however, a carrier of an inherited-chromosomally-integrated human herpesvirus-6A (iciHHV-6A) genome in one 19q telomere. The iciHHV-6A genome was complete in blood DNA, encoding a full set of protein-coding genes. Interestingly, the entire iciHHV-6A genome was absent from the HHV-8-unrelated-PEL-like lymphoma cells despite retention of both copies of chromosome 19. The somatic loss of the 19q-iciHHV-6A genome occurred very early during lymphoma development and we propose it occurred via telomere-loop formation and excision to release a circular viral genome that was subsequently lost. Whether release of the HHV-6A genome from the telomere contributed to lymphomagenesis, or was coincidental, remains unclear but this event may have deregulated the expression of HHV-6A or 19q genes or else disrupted telomere function. To establish the frequency and importance of iciHHV-6 loss from telomeres, the HHV-6 copy number should be assessed in tumours that arise in iciHHV-6 carriers.


Assuntos
Cromossomos Humanos Par 19 , Herpesvirus Humano 6/genética , Linfoma de Efusão Primária/diagnóstico , Provírus/genética , Infecções por Roseolovirus/complicações , Deleção de Sequência , Telômero , Idoso , Feminino , Humanos , Linfoma de Efusão Primária/patologia , Linfoma de Efusão Primária/virologia , Masculino , Análise de Sequência de DNA , Integração Viral
17.
Br J Haematol ; 173(2): 265-73, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26917488

RESUMO

T-cell prolymphocytic leukaemia (T-PLL) is an aggressive leukaemia. The primary genetic alteration in T-PLL are the inv(14)(q11q32)/t(14;14)(q11;q32) leading to TRD/TRA-TCL1A fusion, or the t(X;14)(q28;q11) associated with TRD/TRA-MTCP1 fusion. However, additional cooperating abnormalities are necessary for emergence of the full neoplastic phenotype. Though the pattern of secondary chromosomal aberrations is remarkably conserved, targets of the changes are largely unknown. We analysed a cohort of 43 well-characterized T-PLL for hotspot mutations in the genes JAK3, STAT5B and RHOA. Additionally, we selected a subset of 23 T-PLL cases for mutational screening of 54 genes known to be recurrently mutated in T-cell and other haematological neoplasms. Activating mutations in the investigated regions of the JAK3 and STAT5B genes were detected in 30% (13/43) and 21% (8/39) of the cases, respectively, and were mutually exclusive. Further, we identified mutations in the genes encoding the epigenetic regulators EZH2 in 13% (3/23), TET2 in 17% (4/23) and BCOR in 9% (2/23) of the cases. We confirmed that the JAK-STAT pathway is a major mutational target, and identified epigenetic regulators recurrently mutated in T-PLL. These findings complement the mutational spectrum of secondary aberrations in T-PLL and underscore the potential therapeutical relevance of epigenetic regulators in T-PLL.


Assuntos
Epigênese Genética/genética , Janus Quinase 3/genética , Leucemia Prolinfocítica de Células T/genética , Fator de Transcrição STAT5/genética , Idoso , Biomarcadores Tumorais/genética , Estudos de Coortes , Análise Mutacional de DNA/métodos , Feminino , Marcadores Genéticos/genética , Humanos , Masculino , Pessoa de Meia-Idade , Mutação/genética , Proteínas Proto-Oncogênicas/genética , Recidiva , Proteínas Repressoras/genética , Transdução de Sinais , Proteína rhoA de Ligação ao GTP/genética
18.
Blood ; 128(19): 2319-2326, 2016 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31654069

RESUMO

Chronic lymphocytic leukemia (CLL) can be familial; however, thus far no rare germ line disruptive alleles for CLL have been identified. We performed whole-exome sequencing of 66 CLL families, identifying 4 families where loss-of-function mutations in protection of telomeres 1 (POT1) co-segregated with CLL. The p.Tyr36Cys mutation is predicted to disrupt the interaction between POT1 and the telomeric overhang. The c.1164-1G>A splice-site, p.Gln358SerfsTer13 frameshift, and p.Gln376Arg missense mutations are likely to impact the interaction between POT1 and adrenocortical dysplasia homolog (ACD), which is a part of the telomere-capping shelterin complex. We also identified mutations in ACD (c.752-2A>C) and another shelterin component, telomeric repeat binding factor 2, interacting protein (p.Ala104Pro and p.Arg133Gln), in 3 CLL families. In a complementary analysis of 1083 cases and 5854 controls, the POT1 p.Gln376Arg variant, which has a global minor allele frequency of 0.0005, conferred a 3.61-fold increased risk of CLL (P = .009). This study further highlights telomere dysregulation as a key process in CLL development.

19.
RNA ; 21(11): 1931-42, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26370582

RESUMO

The human hnRNP C is a ubiquitous cellular protein involved in mRNA maturation. Recently, we have shown that this protein specifically recognizes uridine (U) pentamers through its single RNA recognition motif (RRM). However, a large fraction of natural RNA targets of hnRNP C consists of much longer contiguous uridine stretches. To understand how these extended sites are recognized, we studied the binding of the RRM to U-tracts of 8-11 bases. In vivo investigation of internal translation activation of unr (upstream of N-ras) mRNA indicates that the conservation of the entire hnRNP C binding site, UC(U)8, is required for hnRNP C-dependent IRES activation. The assays further suggest a synergistic interplay between hnRNP C monomers, dependent on the protein's ability to oligomerize. In vitro spectroscopic and thermodynamic analyses show that isolated RRMs bind to (U)11 oligomers as dimers. Structural modeling of a ternary double-RRM/RNA complex indicates additionally that two RRM copies can be accommodated on the canonical sequence UC(U)8. The proposed tandem RRM binding is in very good agreement with the transcriptome-wide recognition of extended U-tracts by full-length hnRNP C, which displays a cross-linking pattern consistent with a positively cooperative RRM dimer binding model.


Assuntos
Sítios de Ligação/genética , Ribonucleoproteínas Nucleares Heterogêneas Grupo C/metabolismo , Ligação Proteica/genética , Proteínas com Motivo de Reconhecimento de RNA/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas/genética , Humanos , Transcriptoma/genética , Uridina/genética , Uridina/metabolismo
20.
Genes Chromosomes Cancer ; 54(11): 668-80, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26305789

RESUMO

Chronic lymphocytic leukemia (CLL) is a common disease with highly variable clinical course. Several recurrent chromosomal alterations are associated with prognosis and may guide risk-adapted therapy. We have developed a targeted genome-wide array to provide a robust tool for ascertaining abnormalities in CLL and to overcome limitations of the 4-marker fluorescence in situ hybridization (FISH). DNA from 180 CLL patients were hybridized to the qChip®Hemo array with a high density of probes covering commonly altered loci in CLL (11q22-q23, 13q14, and 17p13), nine focal regions (2p15-p16.1, 2p24.3, 2q13, 2q36.3-q37.1, 3p21.31, 8q24.21, 9p21.3, 10q24.32, and 18q21.32-q21.33) and two larger regions (6q14.1-q22.31 and 7q31.33-q33). Overall, 86% of the cases presented copy number alterations (CNA) by array. There was a high concordance of array findings with FISH (84% sensitivity, 100% specificity); all discrepancies corresponded to subclonal alterations detected only by FISH. A chromothripsis-like pattern was detected in eight cases. Three showed concomitant shattered 5p with gain of TERT along with isochromosome 17q. Presence of 11q loss was associated with shorter time to first treatment (P = 0.003), whereas 17p loss, increased genomic complexity, and chromothripsis were associated with shorter overall survival (P < 0.001, P = 0.001, and P = 0.02, respectively). In conclusion, we have validated a targeted array for the diagnosis of CLL that accurately detects, in a single experiment, all relevant CNAs, genomic complexity, chromothripsis, copy number neutral loss of heterozygosity, and CNAs not covered by the FISH panel. This test may be used as a practical tool to stratify CLL patients for routine diagnostics or clinical trials.


Assuntos
Aberrações Cromossômicas , Leucemia Linfocítica Crônica de Células B/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Dosagem de Genes , Genoma Humano , Humanos , Leucemia Linfocítica Crônica de Células B/diagnóstico , Masculino , Pessoa de Meia-Idade , Mutação , Análise de Sequência com Séries de Oligonucleotídeos/métodos
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