Suchergebnisse

Chronic myeloid leukemia (CML) progresses from a chronic to a blastic phase, where the leukemic cells are proliferative and undifferentiated. The CML is nowadays successfully treated with BCR-ABL kinase inhibitors as imatinib and its derivatives. NUMB is an evolutionary well-conserved protein initially described as a functional antagonist of NOTCH function. NUMB is an endocytic protein associated with receptor internalization, involved in multiple cellular functions. It has been reported that MSI2 protein, a NUMB inhibitor, is upregulated in CML blast crisis, whereas NUMB itself is downregulated. This suggest that NUMB plays a role in the malignant progression of CML. Here we have generated K562 cells (derived from CML in blast crisis) constitutively expressing a dominant negative form of NUMB (dnNUMB). We show that dnNUMB expression confers a high proliferative phenotype to the cells. Importantly, dnNUMB triggers a partial resistance to imatinib in these cells, antagonizing the apoptosis mediated by the drug. Interestingly, imatinib resistance is not linked to p53 status or NOTCH signaling, as K562 lack p53 and imatinib resistance is reproduced in the presence of NOTCH inhibitors. Taken together, our data support the hypothesis that NUMB activation could be a new therapeutic target in CML. ; The work was supported by grants SAF2014-53526 (to JL), BFU2007-67476 and BFU2010-21634 (to MC) from Spanish Ministry of Economy and Competitiveness (MINECO), and RD12/0036/ 0033 (to JL), RD12/0036/0054 (to AB) and RD12/0019/0006 and PI12/01097 (to FM) from Instituto Carlos III, and grant PI-57069 from CICE, FEDER/Fondo de Cohesion Europeo (FSE) de Andalucía 2007–2013 (to FM). The funding from MINECO and Instituto Carlos III was co-sponsored by the European Union FEDER program. EGA was supported with a JAE-doc contract form CSIC, MCL-N was supported by the FPU program from MINECO and LG-G

Rho guanine exchange factors (GEFs), the enzymes that stimulate Rho GTPases, are deemed as potential therapeutic targets owing to their protumorigenic functions. However, the understanding of the spectrum of their pathobiological roles in tumors is still very limited. We report here that the GEF Vav1 unexpectedly possesses tumor-suppressor functions in immature T cells. This function entails the noncatalytic nucleation of complexes between the ubiquitin ligase Cbl-b and the intracellular domain of Notch1 (ICN1) that favors ICN1 ubiquitinylation and degradation. Ablation of Vav1 promotes ICN1 signaling and the development of T cell acute lymphoblastic leukemia (T-ALL). The downregulation of Vav1 is essential for the pathogenesis of human T-ALL of the TLX+ clinical subtype, further underscoring the suppressor role of this pathway ; X.R.B. is supported by grants from the Castilla-León Government (BIO/SA01/15, CSI049U16), Spanish Ministry of Economy and Competitiveness (MINECO) (SAF2015-64556-R, RD12/0036/0002), Worldwide Cancer Research (14-1248), Ramón Areces Foundation, and Spanish Society Against Cancer. L.E. (PI13/00448), A.B. (SAF2013-40922-R, RD12/0036/0054), and M.L.T. (SAF2013-44857-R, RD12/0036/0075) are supported by MINECO grants. Spanish funding is partially supported by the European Regional Development Fund. We thank M. Blázquez for laboratory work, R. Valiente for ChIP-seq analyses, M. Dosil for comments on the manuscript, and CIC facilities' personnel for technical assistance

Altres ajuts: X.R.B. is supported by grants from the Castilla-León Government (BIO/SA01/15, CSI049U16), [.], Worldwide Cancer Research (14-1248), Ramón Areces Foundation, and Spanish Society Against Cancer. [.] Spanish funding is partially supported by the European Regional Development Fund. We thank M. Blázquez for laboratory work, R. Valiente for ChIP-seq analyses, M. Dosil for comments on the manuscript, and CIC facilities' personnel for technical assistance. ; Rho guanine exchange factors (GEFs), the enzymes that stimulate Rho GTPases, are deemed as potential therapeutic targets owing to their protumorigenic functions. However, the understanding of the spectrum of their pathobiological roles in tumors is still very limited. We report here that the GEF Vav1 unexpectedly possesses tumor-suppressor functions in immature T cells. This function entails the noncatalytic nucleation of complexes between the ubiquitin ligase Cbl-b and the intracellular domain of Notch1 (ICN1) that favors ICN1 ubiquitinylation and degradation. Ablation of Vav1 promotes ICN1 signaling and the development of T cell acute lymphoblastic leukemia (T-ALL). The downregulation of Vav1 is essential for the pathogenesis of human T-ALL of the TLX + clinical subtype, further underscoring the suppressor role of this pathway. Robles-Valero et al. find that Vav1 facilitates binding of Cbl-b to the intracellular domain of Notch1 (ICN1) and promotes ICN1 degradation. Loss of Vav1 induces T cell acute lymphoblastic leukemia (T-ALL) by increasing ICN1 signaling, and TLX inhibits Vav1 expression to stimulate ICN1 signaling in TLX + T-ALL.

Adult hematopoietic stem cells (HSCs) are rare multipotent cells in bone marrow that are responsible for generating all blood cell types. HSCs are a heterogeneous group of cells with high plasticity, in part, conferred by epigenetic mechanisms. PHF19, a subunit of the Polycomb repressive complex 2 (PRC2), is preferentially expressed in mouse hematopoietic precursors. Here, we now show that, in stark contrast to results published for other PRC2 subunits, genetic depletion of Phf19 increases HSC identity and quiescence. While proliferation of HSCs is normally triggered by forced mobilization, defects in differentiation impede long-term correct blood production, eventually leading to aberrant hematopoiesis. At molecular level, PHF19 deletion triggers a redistribution of the histone repressive mark H3K27me3, which notably accumulates at blood lineage-specific genes. Our results provide novel insights into how epigenetic mechanisms determine HSC identity, control differentiation, and are key for proper hematopoiesis. ; The work in the Di Croce laboratory is supported by grants from the Spanish of Economy, Industry, and Competitiveness (MEIC) (BFU2016-75008-P), "Fundación Vencer El Cancer" (VEC), the European Regional Development Fund (FEDER), Fundació "La Marató de TV3," and from AGAUR. The laboratory of A.B. is supported by SAF2016-75613-R from the Ministerio de Ciencia, Innovación y Universidades. H.H. is a Miguel Servet (CP14/00229) researcher funded by the Spanish Institute of Health Carlos III (ISCIII) and received funding from the European Union's Horizon 2020 research and innovation programme (MSCA-ITN-2015-675752) and the Ministerio de Ciencia, Innovación y Universidades (SAF2017-89109-P; AEI/FEDER, UE). P.V. was supported by "Fundación Científica de la Asociación Española Contra el Cáncer."

Genetic data indicate that abrogation of Notch-Rbpj or Wnt-β-catenin pathways results in the loss of the intestinal stem cells (ISCs). However, whether the effect of Notch is direct or due to the aberrant differentiation of the transit-amplifying cells into post-mitotic goblet cells is unknown. To address this issue, we have generated composite tamoxifen-inducible intestine-specific genetic mouse models and analyzed the expression of intestinal differentiation markers. Importantly, we found that activation of β-catenin partially rescues the differentiation phenotype of Rbpj deletion mutants, but not the loss of the ISC compartment. Moreover, we identified Bmi1, which is expressed in the ISC and progenitor compartments, as a gene that is co-regulated by Notch and β-catenin. Loss of Bmi1 resulted in reduced proliferation in the ISC compartment accompanied by p16(INK4a) and p19(ARF) (splice variants of Cdkn2a) accumulation, and increased differentiation to the post-mitotic goblet cell lineage that partially mimics Notch loss-of-function defects. Finally, we provide evidence that Bmi1 contributes to ISC self-renewal. ; This work has been supported by the Instituto de Salud Carlos III [PI10/01128], Ministerio de Ciencia e Innovación [ACI2009-0918], Agència de Gestió d'Ajuts Universitaris i de Recerca-Convocatòria Estratègica-2010-0006 and Red Temática de Investigación Cooperativa en Cáncer [RD06/0020/0098, RD12/0036/0054]. The Mar Institute of Medical Research (IMIM) Foundation financed V.R., and she is a recipient of a European Molecular Biology Organization (EMBO) short-term fellowship [ASTF 20-2010]. E.L.-A. is funded by 'Fundación la Caixa' (2010) and the Department of Education, Universities and Research of the Basque Government [BFI-2011]. L.L.E. is an investigator of the Spanish National Health System (SNS) [CES08/006]

Background: Adult T cell acute lymphoblastic leukemia (T-ALL) is a rare disease that affects less than 10 individuals in one million. It has been less studied than its cognate pediatric malignancy, which is more prevalent. A higher percentage of the adult patients relapse, compared to children. It is thus essential to study the mechanisms of relapse of adult T-ALL cases. Results: We profile whole-genome somatic mutations of 19 primary T-ALLs from adult patients and the corresponding relapse malignancies and analyze their evolution upon treatment in comparison with 238 pediatric and young adult ALL cases. We compare the mutational processes and driver mutations active in primary and relapse adult T-ALLs with those of pediatric patients. A precise estimation of clock-like mutations in leukemic cells shows that the emergence of the relapse clone occurs several months before the diagnosis of the primary T-ALL. Specifically, through the doubling time of the leukemic population, we find that in at least 14 out of the 19 patients, the population of relapse leukemia present at the moment of diagnosis comprises more than one but fewer than 108 blasts. Using simulations, we show that in all patients the relapse appears to be driven by genetic mutations. Conclusions: The early appearance of a population of leukemic cells with genetic mechanisms of resistance across adult T-ALL cases constitutes a challenge for treatment. Improving early detection of the malignancy is thus key to prevent its relapse. ; The authors would like to thank the Asociación Española Contra el Cáncer (AECC) for financially supporting this project (GC16173697BIGA). N.L.-B. acknowledges funding from the European Research Council (consolidator grant 682398) and the ERDF/Spanish Ministry of Science, Innovation and Universities–Spanish State Research Agency/DamReMap Project (RTI2018-094095-B-I00). S. G work is supported by the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 754510. I. S is supported by FPI fellowship from Spanish Ministry of Economy and Competitiveness (project reference SAF2015-66084-R). V.G-H. is supported by the AECC (project reference GC16173697BIGA-9). IRB Barcelona is a recipient of a Severo Ochoa Centre of Excellence Award from the Spanish Ministry of Economy and Competitiveness (MINECO; Government of Spain) and is supported by CERCA (Generalitat de Catalunya).

Phosphorylated IKKalpha(p45) is a nuclear active form of the IKKalpha kinase that is induced by the MAP kinases BRAF and TAK1 and promotes tumor growth independent of canonical NF-¿B signaling. Insights into the sources of IKKalpha(p45) activation and its downstream substrates in the nucleus remain to be defined. Here, we discover that IKKalpha(p45) is rapidly activated by DNA damage independent of ATM-ATR, but dependent on BRAF-TAK1-p38-MAPK, and is required for robust ATM activation and efficient DNA repair. Abolishing BRAF or IKKalpha activity attenuates ATM, Chk1, MDC1, Kap1, and 53BP1 phosphorylation, compromises 53BP1 and RIF1 co-recruitment to sites of DNA lesions, and inhibits 53BP1-dependent fusion of dysfunctional telomeres. Furthermore, IKKalpha or BRAF inhibition synergistically enhances the therapeutic potential of 5-FU and irinotecan to eradicate chemotherapy-resistant metastatic human tumors in vivo. Our results implicate BRAF and IKKalpha kinases in the DDR and reveal a combination strategy for cancer treatment. ; This work was funded by grants from Instituto de Salud Carlos III FEDER (PIE15/00008 and PI16/00437), Generalitat de Catalunya 2017SGR135, and the "Xarxa de Bancs de Tumors" sponsored by Pla Director d'Oncologia de Catalunya (XBTC). C.C. is supported by FPI BES-2014-068451 and the EMBO Short-Term Fellowship (na7084). P.M. is supported by funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement #702430. The Boulton lab is supported by The Francis Crick Institute, which receives its core funding from Cancer Research UK (FC0010048), the UK Medical Research Council (FC0010048), and the Wellcome Trust (FC0010048). S.J.B. is funded by European Research Council (ERC) Advanced Investigator Grants (TelMetab) and a Wellcome Trust Senior Investigator Grant. The Centre de Regulació Genòmica/Universitat Pompeu Fabra Proteomics Unit is part of the "Plataforma de Recursos Biomoleculares y Bioinformáticos (ProteoRed)" supported by grant PT13/0001 of Instituto de Salud Carlos III from the Spanish government and "Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya" (2014SGR678). We acknowledge support from the Spanish Ministry of Economy and Competitiveness and "Centro de Excelencia Severo Ochoa 2013-2017" (SEV-2012-0208).