Identification Of A Germline F692L Drug Resistance Variant In Cis With Flt3-ITD In Knock-In Mice

Letter to the Editor.-- Dovey, Oliver M. et al.Internal tandem duplication (ITD) mutations in the juxtamembrane domain of the fms-like tyrosine kinase 3 (FLT3) gene occur in approximately one quarter of cases of acute myeloid leukemia (AML), are associated with constitutive activation of the kinase and confer a poor prognosis.BC is funded by the >China Scholarship Council> for his visiting studies in UK. AM is funded by the Kay Kendall Leukaemia Fund project grant. CG was funded by a Bloodwise Clinical Research Training Fellowship. IV is funded by Spanish Ministerio de Economía y Competitividad subprograma Ramón y Cajal. We thank Servicio Santander Supercomputación for their support. OMD, JLC and GSV are funded by a Wellcome Trust Senior Fellowship in Clinical Science (WT095663MA) and this work was also funded by the Wellcome Trust Sanger InstitutePeer Reviewe

Identification Of A Germline F692L Drug Resistance Variant In Cis With Flt3-ITD In Knock-In Mice

Letter to the Editor.-- Dovey, Oliver M. et al.Internal tandem duplication (ITD) mutations in the juxtamembrane domain of the fms-like tyrosine kinase 3 (FLT3) gene occur in approximately one quarter of cases of acute myeloid leukemia (AML), are associated with constitutive activation of the kinase and confer a poor prognosis.BC is funded by the >China Scholarship Council> for his visiting studies in UK. AM is funded by the Kay Kendall Leukaemia Fund project grant. CG was funded by a Bloodwise Clinical Research Training Fellowship. IV is funded by Spanish Ministerio de Economía y Competitividad subprograma Ramón y Cajal. We thank Servicio Santander Supercomputación for their support. OMD, JLC and GSV are funded by a Wellcome Trust Senior Fellowship in Clinical Science (WT095663MA) and this work was also funded by the Wellcome Trust Sanger InstitutePeer Reviewe

Analysis of T cell receptor clonotypes in tumor microenvironment identifies shared cancer-type-specific signatures.

Despite the conventional view that a truly random V(D)J recombination process should generate a highly diverse immune repertoire, emerging reports suggest that there is a certain bias toward the generation of shared/public immune receptor chains. These studies were performed in viral diseases where public T cell receptors (TCR) appear to confer better protective responses. Selective pressures generating common TCR clonotypes are currently not well understood, but it is believed that they confer a growth advantage. As very little is known about public TCR clonotypes in cancer, here we set out to determine the extent of shared TCR clonotypes in the intra-tumor microenvironments of virus- and non-virus-driven head and neck cancers using TCR sequencing. We report that tumor-infiltrating T cell clonotypes were indeed shared across individuals with the same cancer type, where the majority of shared sequences were specific to the cancer type (i.e., viral versus non-viral). These shared clonotypes were not particularly enriched in EBV-associated nasopharynx cancer but, in both cancers, exhibited distinct characteristics, namely shorter CDR3 lengths, restricted V- and J-gene usages, and also demonstrated convergent V(D)J recombination. Many of these shared TCRs were expressed in patients with a shared HLA background. Pattern recognition of CDR3 amino acid sequences revealed strong convergence to specific pattern motifs, and these motifs were uniquely found to each cancer type. This suggests that they may be enriched for specificity to common antigens found in the tumor microenvironment of different cancers. The identification of shared TCRs in infiltrating tumor T cells not only adds to our understanding of the tumor-adaptive immune recognition but could also serve as disease-specific biomarkers and guide the development of future immunotherapies

Imprinting fidelity in mouse iPSCs depends on sex of donor cell and medium formulation

Funding Information: We would like to thank Sérgio de Almeida, Miguel Casanova and Inês Milagre for critical reading of the manuscript, and the members of the S.T.d.R.’s team for helpful discussions. We also thank Tânia Carvalho and Pedro Ruivo for their help in histological analysis; Judith Webster at Babraham Institute for LC-MS measurements; Bethan Hussey at Sanger Sequencing and Kristina Tabbada at Babraham Institute for assistance with high-throughput sequencing; and the Bioimaging unit as well as Andreia Santos, Rute Gonçalves and Mariana Fernandes of the Flow Cytometry Facility of Instituto de Medicina Molecular João Lobo Antunes for their services and assistance. Work in S.T.d.R.’s team was supported by Fundação para a Ciência e Tecnologia (FCT) Ministério da Ciência, Tecnologia e Ensino Superior (MCTES), Portugal [IC&DT projects PTDC/BEX-BCM/2612/2014 and PTDC/BIA-MOL/29320/2017 as well as projects UIDB/04565/2020 and UIDP/04565/2020 of the Research Unit Institute from Bioengineering and Biosciences – iBB and LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy – i4HB]; S.T.d.R. and A.-V.G. are supported by assistant research contracts from FCT/MCTES (CEECIND/01234/2017 and CEECIND/02085/2018, respectively); M.A and A.C.R. are supported, respectively, by SFRH/BD/151251/2021 and SFRH/BD/137099/2018 PhD fellowships from FCT/MCTES. J.V.G.L is supported by COVID/BD/152624/2022 from FCT/MCTES. MAE-M was supported by a BBSRC Discovery Fellowship (BB/T009713/1) and is now supported by a Snow Medical Fellowship. F.K. is supported by the Babraham Institute Strategic Core Funding and A.M. by BBSRC BBS/E/B/000C0421. B.B.J. work was funded by Fundação para a Ciência e Tecnologia (FCT), and FEDER, LISBOA-01-0145-FEDER-028534, project co-funded by FEDER, through POR Lisboa 2020—Programa Operacional Regional de Lisboa. T.K. is supported by Janko Jamnik Doctoral Scholarship from National Institute of Chemistry. Funding Information: We would like to thank Sérgio de Almeida, Miguel Casanova and Inês Milagre for critical reading of the manuscript, and the members of the S.T.d.R.’s team for helpful discussions. We also thank Tânia Carvalho and Pedro Ruivo for their help in histological analysis; Judith Webster at Babraham Institute for LC-MS measurements; Bethan Hussey at Sanger Sequencing and Kristina Tabbada at Babraham Institute for assistance with high-throughput sequencing; and the Bioimaging unit as well as Andreia Santos, Rute Gonçalves and Mariana Fernandes of the Flow Cytometry Facility of Instituto de Medicina Molecular João Lobo Antunes for their services and assistance. Work in S.T.d.R.’s team was supported by Fundação para a Ciência e Tecnologia (FCT) Ministério da Ciência, Tecnologia e Ensino Superior (MCTES), Portugal [IC&DT projects PTDC/BEX-BCM/2612/2014 and PTDC/BIA-MOL/29320/2017 as well as projects UIDB/04565/2020 and UIDP/04565/2020 of the Research Unit Institute from Bioengineering and Biosciences – iBB and LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy – i4HB]; S.T.d.R. and A.-V.G. are supported by assistant research contracts from FCT/MCTES (CEECIND/01234/2017 and CEECIND/02085/2018, respectively); M.A and A.C.R. are supported, respectively, by SFRH/BD/151251/2021 and SFRH/BD/137099/2018 PhD fellowships from FCT/MCTES. J.V.G.L is supported by COVID/BD/152624/2022 from FCT/MCTES. MAE-M was supported by a BBSRC Discovery Fellowship (BB/T009713/1) and is now supported by a Snow Medical Fellowship. F.K. is supported by the Babraham Institute Strategic Core Funding and A.M. by BBSRC BBS/E/B/000C0421. B.B.J. work was funded by Fundação para a Ciência e Tecnologia (FCT), and FEDER, LISBOA-01-0145-FEDER-028534, project co-funded by FEDER, through POR Lisboa 2020—Programa Operacional Regional de Lisboa. T.K. is supported by Janko Jamnik Doctoral Scholarship from National Institute of Chemistry. Publisher Copyright: © 2022, The Author(s).Reprogramming of somatic cells into induced Pluripotent Stem Cells (iPSCs) is a major leap towards personalised approaches to disease modelling and cell-replacement therapies. However, we still lack the ability to fully control the epigenetic status of iPSCs, which is a major hurdle for their downstream applications. Epigenetic fidelity can be tracked by genomic imprinting, a phenomenon dependent on DNA methylation, which is frequently perturbed in iPSCs by yet unknown reasons. To try to understand the causes underlying these defects, we conducted a thorough imprinting analysis using IMPLICON, a high-throughput method measuring DNA methylation levels, in multiple female and male murine iPSC lines generated under different experimental conditions. Our results show that imprinting defects are remarkably common in iPSCs, but their nature depends on the sex of donor cells and their response to culture conditions. Imprints in female iPSCs resist the initial genome-wide DNA demethylation wave during reprogramming, but ultimately cells accumulate hypomethylation defects irrespective of culture medium formulations. In contrast, imprinting defects on male iPSCs depends on the experimental conditions and arise during reprogramming, being mitigated by the addition of vitamin C (VitC). Our findings are fundamental to further optimise reprogramming strategies and generate iPSCs with a stable epigenome.publishersversionpublishe

Molecular synergy underlies the co-occurrence patterns and phenotype of NPM1-mutant acute myeloid leukemia

NPM1 mutations define the commonest subgroup of acute myeloid leukemia (AML) and frequently co-occur with FLT3 internal tandem duplications (ITD) or, less commonly, NRAS or KRAS mutations. Co-occurrence of mutant NPM1 with FLT3-ITD carries a significantly worse prognosis than NPM1-RAS combinations. To understand the molecular basis of these observations, we compare the effects of the 2 combinations on hematopoiesis and leukemogenesis in knock-in mice. Early effects of these mutations on hematopoiesis show that compound Npm1cA/+;NrasG12D/+ or Npm1cA;Flt3ITD share a number of features: Hox gene overexpression, enhanced self-renewal, expansion of hematopoietic progenitors, and myeloid differentiation bias. However, Npm1cA;Flt3ITD mutants displayed significantly higher peripheral leukocyte counts, early depletion of common lymphoid progenitors, and a monocytic bias in comparison with the granulocytic bias in Npm1cA/+;NrasG12D/+ mutants. Underlying this was a striking molecular synergy manifested as a dramatically altered gene expression profile in Npm1cA;Flt3ITD, but not Npm1cA/+;NrasG12D/+, progenitors compared with wild-type. Both double-mutant models developed high-penetrance AML, although latency was significantly longer with Npm1cA/+;NrasG12D/+. During AML evolution, both models acquired additional copies of the mutant Flt3 or Nras alleles, but only Npm1cA/+;NrasG12D/+ mice showed acquisition of other human AML mutations, including IDH1 R132Q. We also find, using primary Cas9-expressing AMLs, that Hoxa genes and selected interactors or downstream targets are required for survival of both types of double-mutant AML. Our results show that molecular complementarity underlies the higher frequency and significantly worse prognosis associated with NPM1c/FLT3-ITD vs NPM1/NRAS-G12D-mutant AML and functionally confirm the role of HOXA genes in NPM1c-driven AML

Tbx1 regulates Vegfr3 and is required for lymphatic vessel development

Defects in lymphangiogenesis are added to the broad clinical manifestations of DiGeorge syndrome, caused by deletion of the T box transcription factor Tbx1

Vitamin D Receptor Controls Cell Stemness in Acute Myeloid Leukemia and in Normal Bone Marrow.

Vitamin D (VD) is a known differentiating agent, but the role of VD receptor (VDR) is still incompletely described in acute myeloid leukemia (AML), whose treatment is based mostly on antimitotic chemotherapy. Here, we present an unexpected role of VDR in normal hematopoiesis and in leukemogenesis. Limited VDR expression is associated with impaired myeloid progenitor differentiation and is a new prognostic factor in AML. In mice, the lack of Vdr results in increased numbers of hematopoietic and leukemia stem cells and quiescent hematopoietic stem cells. In addition, malignant transformation of Vdr-/- cells results in myeloid differentiation block and increases self-renewal. Vdr promoter is methylated in AML as in CD34+ cells, and demethylating agents induce VDR expression. Association of VDR agonists with hypomethylating agents promotes leukemia stem cell exhaustion and decreases tumor burden in AML mouse models. Thus, Vdr functions as a regulator of stem cell homeostasis and leukemic propagation

Genetic modification of primary human B cells to model high-grade lymphoma

Sequencing studies of diffuse large B cell lymphoma (DLBCL) have identified hundreds of recurrently altered genes. However, it remains largely unknown whether and how these mutations may contribute to lymphomagenesis, either individually or in combination. Existing strategies to address this problem predominantly utilize cell lines, which are limited by their initial characteristics and subsequent adaptions to prolonged in vitro culture. Here, we describe a co-culture system that enables the ex vivo expansion and viral transduction of primary human germinal center B cells. Incorporation of CRISPR/Cas9 technology enables high-throughput functional interrogation of genes recurrently mutated in DLBCL. Using a backbone of BCL2 with either BCL6 or MYC, we identify co-operating genetic alterations that promote growth or even full transformation into synthetically engineered DLBCL models. The resulting tumors can be expanded and sequentially transplanted in vivo, providing a scalable platform to test putative cancer genes and to create mutation-directed, bespoke lymphoma models

Genetic modification of primary human B cells to model high-grade lymphoma

Abstract: Sequencing studies of diffuse large B cell lymphoma (DLBCL) have identified hundreds of recurrently altered genes. However, it remains largely unknown whether and how these mutations may contribute to lymphomagenesis, either individually or in combination. Existing strategies to address this problem predominantly utilize cell lines, which are limited by their initial characteristics and subsequent adaptions to prolonged in vitro culture. Here, we describe a co-culture system that enables the ex vivo expansion and viral transduction of primary human germinal center B cells. Incorporation of CRISPR/Cas9 technology enables high-throughput functional interrogation of genes recurrently mutated in DLBCL. Using a backbone of BCL2 with either BCL6 or MYC, we identify co-operating genetic alterations that promote growth or even full transformation into synthetically engineered DLBCL models. The resulting tumors can be expanded and sequentially transplanted in vivo, providing a scalable platform to test putative cancer genes and to create mutation-directed, bespoke lymphoma models