Bone marrow MSC from pediatric patients with B-ALL highly immunosuppress T-cell responses but do not compromise CD19-CAR T-cell activity

Altres ajuts Funding Financial support for this work was obtained from the Obra Social La Caixa (LCF/PR/HR19/52160011), the Leo Messi Foundation, and the 'Heroes hasta la médula' initiative to PM. SRZ was supported by a Marie Sklodowska Curie Fellowship (GA 795833). MV is supported by a Juan de la Cierva fellowship from the MINECO. PM is an investigator of the Spanish Cell Therapy cooperative network (TERCEL).Background Although adoptive transfer of CD19-directed chimeric antigen receptor (CAR) T-cells (CD19-CAR T-cells) achieves high rates of complete response in patients with B-cell acute lymphoblastic leukemia (B-ALL), relapse is common. Bone marrow (BM) mesenchymal stem/stromal cells (BM-MSC) are key components of the hematopoietic niche and are implicated in B-ALL pathogenesis and therapy resistance. MSC exert an immunosuppressive effect on T-cells; however, their impact on CD19-CAR T-cell activity is understudied. Methods We performed a detailed characterization of BM-MSC from pediatric patients with B-ALL (B-ALL BM-MSC), evaluated their immunomodulatory properties and their impact on CD19-CAR T-cell activity in vitro using microscopy, qRT-PCR, ELISA, flow cytometry analysis and in vivo using a preclinical model of severe colitis and a B-ALL xenograft model. Results While B-ALL BM-MSC were less proliferative than those from age-matched healthy donors (HD), the morphology, immunophenotype, differentiation potential and chemoprotection was very similar. Likewise, both BM-MSC populations were equally immunosuppressive in vitro and anti-inflammatory in an in vivo model of severe colitis. Interestingly, BM-MSC failed to impair CD19-CAR T-cell cytotoxicity or cytokine production in vitro using B-ALL cell lines and primary B-ALL cells. Finally, the growth of NALM6 cells was controlled in vivo by CD19-CAR T-cells irrespective of the absence/presence of BM-MSC. Conclusions Collectively, our data demonstrate that pediatric B-ALL and HD BM-MSC equally immunosuppress T-cell responses but do not compromise CD19-CAR T-cell activity

Robust In Vitro and In Vivo Immunosuppressive and Anti-inflammatory Properties of Inducible Caspase-9-mediated Apoptotic Mesenchymal Stromal/Stem Cell.

Mesenchymal stromal stem/cells (MSC) therapies are clinically used in a wide range of disorders based on their robust HLA-independent immunosuppressive and anti-inflammatory properties. However, the mechanisms underlying MSC therapeutic activity remain elusive as demonstrated by the unpredictable therapeutic efficacy of MSC infusions reported in multiple clinical trials. A seminal recent study showed that infused MSCs are actively induced to undergo apoptosis by recipient cytotoxic T cells, a mechanism that triggers in vivo recipient-induced immunomodulation by such apoptotic MSCs, and the need for such recipient cytotoxic cell activity could be replaced by the administration of ex vivo-generated apoptotic MSCs. Moreover, the use of MSC-derived extracellular vesicles (MSC-EVs) is being actively explored as a cell-free therapeutic alternative over the parental MSCs. We hypothesized that the introduction of a "suicide gene" switch into MSCs may offer on-demand in vivo apoptosis of transplanted MSCs. Here, we prompted to investigate the utility of the iCasp9/AP1903 suicide gene system in inducing apoptosis of MSCs. iCasp9/AP1903-induced apoptotic MSCs (MSCiCasp9+) were tested in vitro and in in vivo models of acute colitis. Our data show a very similar and robust immunosuppressive and anti-inflammatory properties of both "parental" alive MSCGFP+ cells and apoptotic MSCiCasp9+ cells in vitro and in vivo regardless of whether apoptosis was induced in vivo or in vitro before administering MSCiCasp9+ lysates. This development of an efficient iCasp9 switch may potentiate the safety of MSC-based therapies in the case of an adverse event and, will also circumvent current logistic technical limitations and biological uncertainties associated to MSC-EVs.The financial support for this work was obtained from Health Canada (H4080-144541) to P.M. M.V. and B.L.-M. were supported by a Juan de la Cierva fellowship by the Spanish Ministry of Science and Innovation (IJCI-2017-3317) and a fellowship from the Spanish Association of Cancer Research (AECC), respectively

The insecticides permethrin and chlorpyrifos show limited genotoxicity and no leukemogenic potential in human and murine hematopoietic stem progenitor cells

Altres ajuts: European Food and Safety Authority, EFSA.PRAS.2018.04-CT1; Consejo Nacional de Ciencia y Tecnología, CB-2012-01-183467; Centro de Investigación Biomédica en Red en Cáncer, PID2019-104695RBI00; Asociación Española Contra el Cáncer, AECC INVES211226MOLI

A human genome editing-based MLL::AF4 B-cell ALL model recapitulates key cellular and molecular leukemogenic features

The cellular ontogeny and location of the MLL-breakpoint influence the capacity of MLL-edited CD34+ HSPCs to initiate pro-B-ALL, and recapitulate the molecular features of MLL-AF4+ infant B-ALL patients. We provide key insights into the cellular-molecular leukemogenic determinants of MLL-AF4+ infant B-ALL

Chromosomal instability in aneuploid acute lymphoblastic leukemia associates with disease progression

Chromosomal instability (CIN) lies at the core of cancer development leading to aneuploidy, chromosomal copy-number heterogeneity (chr-CNH) and ultimately, unfavorable clinical outcomes. Despite its ubiquity in cancer, the presence of CIN in childhood B-cell acute lymphoblastic leukemia (cB-ALL), the most frequent pediatric cancer showing high frequencies of aneuploidy, remains unknown. Here, we elucidate the presence of CIN in aneuploid cB-ALL subtypes using single-cell whole-genome sequencing of primary cB-ALL samples and by generating and functionally characterizing patient-derived xenograft models (cB-ALL-PDX). We report higher rates of CIN across aneuploid than in euploid cB-ALL that strongly correlate with intraclonal chr-CNH and overall survival in mice. This association was further supported by in silico mathematical modeling. Moreover, mass-spectrometry analyses of cB-ALL-PDX revealed a "CIN signature" enriched in mitotic-spindle regulatory pathways, which was confirmed by RNA-sequencing of a large cohort of cB-ALL samples. The link between the presence of CIN in aneuploid cB-ALL and disease progression opens new possibilities for patient stratification and offers a promising new avenue as a therapeutic target in cB-ALL treatment.</p

Integrative methylome-transcriptome analysis unravels cancer cell vulnerabilities in infant MLL-rearranged B cell acute lymphoblastic leukemia

B cell acute lymphoblastic leukemia (B-ALL) is the most common childhood cancer. As predicted by its prenatal origin, infant B-ALL (iB-ALL) shows an exceptionally silent DNA mutational landscape, suggesting that alternative epigenetic mechanisms may substantially contribute to its leukemogenesis. Here, we have integrated genome-wide DNA methylome and transcriptome data from 69 patients with de novo MLL-rearranged leukemia (MLLr) and non-MLLr iB-ALL leukemia uniformly treated according to the Interfant-99/06 protocol. iB-ALL methylome signatures display a plethora of common and specific alterations associated with chromatin states related to enhancer and transcriptional control in normal hematopoietic cells. DNA methylation, gene expression, and gene coexpression network analyses segregated MLLr away from non-MLLr iB-ALL and identified a coordinated and enriched expression of the AP-1 complex members FOS and JUN and RUNX factors in MLLr iB-ALL, consistent with the significant enrichment of hypomethylated CpGs in these genes. Integrative methylome-transcriptome analysis identified consistent cancer cell vulnerabilities, revealed a robust iB-ALL–specific gene expression–correlating dmCpG signature, and confirmed an epigenetic control of AP-1 and RUNX members in reshaping the molecular network of MLLr iB-ALL. Finally, pharmacological inhibition or functional ablation of AP-1 dramatically impaired MLLr-leukemic growth in vitro and in vivo using MLLr-iB-ALL patient–derived xenografts, providing rationale for new therapeutic avenues in MLLr-iB-ALL.We thank CERCA/Generalitat de Catalunya (SGR180) and Fundació Josep Carreras-Obra Social la Caixa for their institutional support. Financial support for this work was obtained from the European Research Council (CoG-2014-646903 and PoC-2018-811220 to PM), the Spanish Ministry of Economy and Competitiveness (SAF-2019-108160-R and SAF2016-76758-R to PM and IV, respectively), the Spanish Association against cancer (AECC-CI-2015 and PROYE18061FERN to CB and MFF), the Fundación Uno entre Cienmil (to PM), the Health Institute Carlos III (ISCIII/FEDER, PI17/01028, PI15/00892, PI18/01527 to CB and AFF/MFF, respectively). We also acknowledge the Plan de Ciencia, Tecnología e Innovación from the Asturias Government cofunding 2018–2022/FEDER (IDI/2018/146to MFF). MFF also acknowledges funding from Fundación General CSIC (0348_CIE_6_E). PM also acknowledges financial support from Fundación Leo Messi. JRT and MV are supported by Juan de la Cierva fellowships by the Spanish Ministry of Science and Innovation (FJCI-2015-26965, IJC2018-36825-I, IJCI-2017-3317) and IUOPA-ISPA-FINBA (The IUOPA is supported by the Obra Social Cajastur-Liberbank, Spain). RTR is supported by a fellowship from the AECC scientific foundation. RFP and PSO are supported by the Severo Ochoa program (BP17-114 and BP17-165, respectively).Peer reviewe

Impaired Condensin Complex and Aurora B kinase underlie mitotic and chromosomal defects in hyperdiploid B-cell ALL

B-cell acute lymphoblastic leukemia (B-ALL) is the most common pediatric cancer, and high-hyperdiploidy (HyperD) identifies the most common subtype of pediatric B-ALL. Despite HyperD is an initiating oncogenic event affiliated to childhood B-ALL, the mitotic and chromosomal defects associated to HyperD B-ALL (HyperD-ALL) remain poorly characterized. Here, we have used 54 primary pediatric B-ALL samples to characterize the cellular-molecular mechanisms underlying the mitotic/chromosome defects predicated to be early pathogenic contributors in HyperD-ALL. We report that HyperD-ALL blasts are low proliferative and show a delay in early mitosis at prometaphase, associated to chromosome alignment defects at the metaphase plate leading to robust chromosome segregation defects and non-modal karyotypes. Mechanistically, biochemical, functional and mass-spectrometry assays revealed that condensin complex is impaired in HyperD-ALL cells, leading to chromosome hypocondensation, loss of centromere stiffness and mis-localization of the chromosome passenger complex proteins Aurora B Kinase (AURKB) and Survivin in early mitosis. HyperD-ALL cells show chromatid cohesion defects and impaired spindle assembly checkpoint (SAC) thus undergoing mitotic slippage due to defective AURKB and impaired SAC activity, downstream of condensin complex defects. Chromosome structure/condensation defects and hyperdiploidy were reproduced in healthy CD34+ stem/progenitor cells upon inhibition of AURKB and/or SAC. Collectively, hyperdiploid B-ALL is associated to defective condensin complex, AURKB and SAC

Nous reguladors en la via de Wnt

La via canònica de Wnt és essencial pel desenvolupament embrionari i per la proliferació cel·lular. A més, la desregulació d’aquesta via causa diferents malalties, com per exemple el càncer. La unió del lligand Wnt als receptors específics promou la fosforilació de Dvl-2 per una quinasa directament associada a p120-catenina, la CK1ε, i indueix una cascada d’activació que inhibeix l’activitat de la quinasa GSK-3 sobre la β-catenina. Com a resultat, la β-catenina s’estabilitza i es transloca al nucli on activa l’expressió de gens diana. Els nostres resultats expliquen com la CK1ε és activada ràpidament en Wnt i permet els diferents esdeveniments que acumulen la β-catenina. Prèviament s’havia descrit que la CK1ε presenta un domini autoregulador que inhibeix l’activitat quinasa de la CK1ε quan aquest està fosforilat, suggerint que es necessita una fosfatasa encara no descrita perquè s’activi la senyalització de Wnt. En aquest treball es mostra que la PP2A permet la defosforilació de la CK1ε en Wnt, i també s’ha identificat la PR61ε com la subunitat reguladora de la PP2A que controla l’activació de CK1ε. A més, la PR61ε interacciona directament amb el receptor Fz i s’associa al complex LRP5/6-p120-catenina-CK1ε després de l’activació de Wnt. En global, aquests resultats suggereixen que la PR61ε regula específicament la defosforilació de la CK1ε mediada per la PP2A, i té un paper essencial en la senyalització de Wnt. Un altre pas determinant de l’activació de la via de Wnt és la inhibició de l’activitat de la GSK-3, tot i que el mecanisme pel qual s’inactiva la quinasa encara és matèria de debat. S’han proposat dos models per explicar-ho, un dependent del reclutament de la GSK-3 al correceptor LRP5/6 fosforilat, que crea un lloc d’inhibició, i l’altre basat en el segrest de la quinasa dins de cossos multivesiculars (MVBs). Degut a que el nostre grup ha descobert una connexió directa entre les cadherines i la p120-catenina (dues proteïnes involucrades en les unions adherents) amb el correceptor LRP5/6, es va hipotetitzar que les cadherines podrien estar involucrades en l’endocitosi de la GSK-3 dependent dels factors Wnt. Els nostres resultats demostren que el complex receptor de Wnt que conté la GSK-3, s’internalitza dins de MVBs, i que aquesta endocitosi depèn de la dissociació prèvia de la p120-catenina-cadherina del correceptor LRP5/6. La disrupció de la interacció cadherina-LRP5/6 és regulada per la fosforilació de la cadherina i requereix de la separació prèvia de la p120-catenina. D’aquesta manera, mutants de la p120-catenina i de la cadherina que no es dissocien del complex bloquegen el segrest de la GSK-3 dins de MVBs. Aquests mutants inhibeixen l’acumulació de β-catenina, tot i que no de forma total. Aquests resultats expliquen com es segresta la GSK-3 dins dels MVBs i suggereixen que aquest mecanisme d’internalització, juntament amb la inhibició de la GSK-3 per la interacció directa amb l’LRP5/6 fosforilat, són necessaris per la completa estabilització de la β-catenina en Wnt.Canonical Wnt signalling is essential for embryonic development and cell proliferation. Deregulation of this pathway leads to some diseases, such as cancer. Binding of extracellular Wnt ligands to specific receptors induces the phosphorylation of Dvl-2 protein by CK1ε- associated-p120-catenin kinase, and a cascade of events that inhibit the activity of GSK3 kinase on β-catenin. As a result, β-catenin is stabilized and translocated to the nucleus where it activates the expression of target genes. Our results explain how CK1ε is quickly activated in Wnt signalling, allowing the cascade of events that accumulate β-catenin. It was previously described that CK1ε presents an autoregulation domain which strongly inhibits CK1ε kinase activity when it is phosphorylated, suggesting that a phosphatase is required to activate Wnt signalling. However, which phosphatase dephosphorylates CK1ε in Wnt and how this phosphatase regulates the pathway were not clear. In this study, we have described that PP2A permits the dephosphorylation of CK1ε upon Wnt, and we have also identified PR61ε as the regulatory subunit of PP2A that controls this CK1ε activation. PR61ε directly interacts with Fz receptor, and associates with LRP5/6-p120-catenin-CK1ε complex upon Wnt activation. Taken together, these results suggest that PR61ε specifically regulates PP2A-mediated CK1ε dephosphorylation and plays an essential role in Wnt signaling. Another key step in the pathway is the local inhibition of GSK3 activity on β-catenin, although the mechanism of this inactivation remains unclear. Two models have been proposed, one dependent on the recruitment and subsequent block of GSK3 by phosphorylated LRP5/6 coreceptor that creates an inhibitory site, and another one based on its sequestration into multivesicular bodies (MVBs). Since our group has uncovered a physical link between cadherins and p120-catenin (two proteins involved in adherens junctions) with the Wnt coreceptor LRP5/6, we wonder whether cadherins may be involved in the endocytosis of GSK3 triggered by Wnt factors. Our results demonstrate that Wnt receptor complexes containing GSK3 are internalized into multivesicular bodies and this endocytosis depends on the previous dissociation of p120-catenin and cadherin from LRP5/6 coreceptor. Thus, disruption of cadherin-LRP5/6 interaction is regulated by cadherin phosphorylation and requires the previous release of p120-catenin. Accordingly, p120-catenin and cadherin mutants unable to dissociate from the complex block GSK3 sequestration into MVBs. These mutants substantially inhibit, but do not completely prevent, the β-catenin accumulation caused by Wnt. These results elucidate how GSK3 is sequestered into MVBs and suggest that this mechanism of internalization together with the inhibition of GSK3 by direct interaction with phosphorylated LRP5/6, are both required for complete β-catenin stabilization upon Wnt stimulation

Nous reguladors en la via de Wnt

La via canònica de Wnt és essencial pel desenvolupament embrionari i per la proliferació cel·lular. A més, la desregulació d'aquesta via causa diferents malalties, com per exemple el càncer. La unió del lligand Wnt als receptors específics promou la fosforilació de Dvl-2 per una quinasa directament associada a p120-catenina, la CK1ε, i indueix una cascada d'activació que inhibeix l'activitat de la quinasa GSK-3 sobre la β-catenina. Com a resultat, la β-catenina s'estabilitza i es transloca al nucli on activa l'expressió de gens diana. Els nostres resultats expliquen com la CK1ε és activada ràpidament en Wnt i permet els diferents esdeveniments que acumulen la β-catenina. Prèviament s'havia descrit que la CK1ε presenta un domini autoregulador que inhibeix l'activitat quinasa de la CK1ε quan aquest està fosforilat, suggerint que es necessita una fosfatasa encara no descrita perquè s'activi la senyalització de Wnt. En aquest treball es mostra que la PP2A permet la defosforilació de la CK1ε en Wnt, i també s'ha identificat la PR61ε com la subunitat reguladora de la PP2A que controla l'activació de CK1ε. A més, la PR61ε interacciona directament amb el receptor Fz i s'associa al complex LRP5/6-p120-catenina-CK1ε després de l'activació de Wnt. En global, aquests resultats suggereixen que la PR61ε regula específicament la defosforilació de la CK1ε mediada per la PP2A, i té un paper essencial en la senyalització de Wnt. Un altre pas determinant de l'activació de la via de Wnt és la inhibició de l'activitat de la GSK-3, tot i que el mecanisme pel qual s'inactiva la quinasa encara és matèria de debat. S'han proposat dos models per explicar-ho, un dependent del reclutament de la GSK-3 al correceptor LRP5/6 fosforilat, que crea un lloc d'inhibició, i l'altre basat en el segrest de la quinasa dins de cossos multivesiculars (MVBs). Degut a que el nostre grup ha descobert una connexió directa entre les cadherines i la p120-catenina (dues proteïnes involucrades en les unions adherents) amb el correceptor LRP5/6, es va hipotetitzar que les cadherines podrien estar involucrades en l'endocitosi de la GSK-3 dependent dels factors Wnt. Els nostres resultats demostren que el complex receptor de Wnt que conté la GSK-3, s'internalitza dins de MVBs, i que aquesta endocitosi depèn de la dissociació prèvia de la p120-catenina-cadherina del correceptor LRP5/6. La disrupció de la interacció cadherina-LRP5/6 és regulada per la fosforilació de la cadherina i requereix de la separació prèvia de la p120-catenina. D'aquesta manera, mutants de la p120-catenina i de la cadherina que no es dissocien del complex bloquegen el segrest de la GSK-3 dins de MVBs. Aquests mutants inhibeixen l'acumulació de β-catenina, tot i que no de forma total. Aquests resultats expliquen com es segresta la GSK-3 dins dels MVBs i suggereixen que aquest mecanisme d'internalització, juntament amb la inhibició de la GSK-3 per la interacció directa amb l'LRP5/6 fosforilat, són necessaris per la completa estabilització de la β-catenina en Wnt.Canonical Wnt signalling is essential for embryonic development and cell proliferation. Deregulation of this pathway leads to some diseases, such as cancer. Binding of extracellular Wnt ligands to specific receptors induces the phosphorylation of Dvl-2 protein by CK1ε- associated-p120-catenin kinase, and a cascade of events that inhibit the activity of GSK3 kinase on β-catenin. As a result, β-catenin is stabilized and translocated to the nucleus where it activates the expression of target genes. Our results explain how CK1ε is quickly activated in Wnt signalling, allowing the cascade of events that accumulate β-catenin. It was previously described that CK1ε presents an autoregulation domain which strongly inhibits CK1ε kinase activity when it is phosphorylated, suggesting that a phosphatase is required to activate Wnt signalling. However, which phosphatase dephosphorylates CK1ε in Wnt and how this phosphatase regulates the pathway were not clear. In this study, we have described that PP2A permits the dephosphorylation of CK1ε upon Wnt, and we have also identified PR61ε as the regulatory subunit of PP2A that controls this CK1ε activation. PR61ε directly interacts with Fz receptor, and associates with LRP5/6-p120-catenin-CK1ε complex upon Wnt activation. Taken together, these results suggest that PR61ε specifically regulates PP2A-mediated CK1ε dephosphorylation and plays an essential role in Wnt signaling. Another key step in the pathway is the local inhibition of GSK3 activity on β-catenin, although the mechanism of this inactivation remains unclear. Two models have been proposed, one dependent on the recruitment and subsequent block of GSK3 by phosphorylated LRP5/6 coreceptor that creates an inhibitory site, and another one based on its sequestration into multivesicular bodies (MVBs). Since our group has uncovered a physical link between cadherins and p120-catenin (two proteins involved in adherens junctions) with the Wnt coreceptor LRP5/6, we wonder whether cadherins may be involved in the endocytosis of GSK3 triggered by Wnt factors. Our results demonstrate that Wnt receptor complexes containing GSK3 are internalized into multivesicular bodies and this endocytosis depends on the previous dissociation of p120-catenin and cadherin from LRP5/6 coreceptor. Thus, disruption of cadherin-LRP5/6 interaction is regulated by cadherin phosphorylation and requires the previous release of p120-catenin. Accordingly, p120-catenin and cadherin mutants unable to dissociate from the complex block GSK3 sequestration into MVBs. These mutants substantially inhibit, but do not completely prevent, the β-catenin accumulation caused by Wnt. These results elucidate how GSK3 is sequestered into MVBs and suggest that this mechanism of internalization together with the inhibition of GSK3 by direct interaction with phosphorylated LRP5/6, are both required for complete β-catenin stabilization upon Wnt stimulation