Hematology
Abstract
MYB fusions are recurrently found in select cancers, including blastic plasmacytoid dendritic cell neoplasm (BPDCN), an acute leukemia with poor prognosis. They are markedly enriched in BPDCN compared to other blood cancers, and in some patients are the only obvious somatic mutation detected. This suggests they may alone be sufficient to drive dendritic cell transformation. MYB fusions are hypothesized to alter the normal transcription factor activity of MYB, but mechanistically how they promote leukemogenesis is poorly understood. Using CUT&RUN chromatin profiling, we found that in BPDCN leukemogenesis, MYB switches from being a regulator of dendritic cell lineage genes to aberrantly regulating G2/M cell cycle control genes. MYB fusions found in BPDCN patients increased the magnitude of DNA binding at these locations, and this was linked to BPDCN-associated gene expression changes. Furthermore, expression of MYB fusions in vivo impaired dendritic cell differentiation and induced transformation to generate a mouse model of myeloid-dendritic acute leukemia. Therapeutically, we present evidence that all-trans retinoic acid (ATRA) may cause loss of MYB protein and cell death in BPDCN.
Authors
Christopher A.G. Booth, Juliette M. Bouyssou, Katsuhiro Togami, Olivier Armand, Hembly G. Rivas, Kezhi Yan, Siobhan Rice, Shuyuan Cheng, Emily M. Lachtara, Jean-Pierre Bourquin, Alex Kentsis, Esther Rheinbay, James A. DeCaprio, Andrew A. Lane
Abstract
Thrombopoietin (TPO) is a plasma glycoprotein that binds its receptor on megakaryocytes (MK) and MK progenitors, resulting in enhanced platelet production. The mechanism by which TPO is secreted from hepatocytes remains poorly understood. LMAN1 and MCFD2 form a complex at the endoplasmic reticulum membrane, recruiting cargo proteins into COPII vesicles for secretion. In this study, we showed that LMAN1 deficient mice (with complete germline LMAN1 deficiency) exhibited mild thrombocytopenia, whereas the platelet count was entirely normal in mice with approximately 7% Lman1 expression. Surprisingly, mice deleted for Mcfd2 did not exhibit thrombocytopenia. Analysis of peripheral blood from LMAN1 deficient mice demonstrated normal platelet size and normal morphology of dense and alpha granules. LMAN1 deficient mice exhibited a trend toward reduced MK and MK progenitors in the bone marrow. We next showed that hepatocyte-specific but not hematopoietic Lman1 deletion results in thrombocytopenia, with plasma TPO level reduced in LMAN1 deficient mice, despite normal Tpo mRNA levels in LMAN1 deficient livers. TPO and LMAN1 interacted by co-immunoprecipitation in a heterologous cell line and TPO accumulated intracellularly in LMAN1 deleted cells. Altogether, these studies confirmed the hepatocyte as the cell of origin for TPO production in vivo and were consistent with LMAN1 as the endoplasmic reticulum cargo receptor that mediates the efficient secretion of TPO. To our knowledge, TPO is the first example of an LMAN1-dependent cargo that is independent of MCFD2.
Authors
Lesley A. Everett, Zesen Lin, Ann Friedman, Vi T. Tang, Greggory Myers, Ginette Balbin-Cuesta, Richard King, Guojing Zhu, Beth McGee, Rami Khoriaty
Abstract
Despite the advances in the understanding and treatment of myeloproliferative neoplasm (MPN), the disease remains incurable with the risk of evolution to AML or myelofibrosis (MF). Unfortunately, the evolution of the disease to MF remains still poorly understood impeding preventive and therapeutic options. Recent studies in solid tumor microenvironment and organ fibrosis have shed instrumental insights on their respective pathogenesis and drug resistance, yet such precise data are lacking in MPN. In this study, through a patient-sample driven transcriptomic and epigenetic description of the MF microenvironment landscape and cell-based analyses, we identify HOXB7 overexpression and more precisely a novel TGFβ-Wnt-HOXB7 pathway as associated to a pro-fibrotic and pro-osteoblastic biased differentiation of mesenchymal stromal cells (MSCs). Using gene-based and chemical inhibition of this pathway we reverse the abnormal phenotype of MSCs from myelofibrosis patients, providing the MPN field with a potential novel target to prevent and manage evolution to MF.
Authors
Saravanan Ganesan, Sarah Awan-Toor, Fabien Guidez, Nabih Maslah, Rifkath Rahimy, Céline Aoun, Panhong Gou, Chloé Guiguen, Juliette Soret, Odonchimeg Ravdan, Valeria Bisio, Nicolas Dulphy, Camille Lobry, Marie-Hélène Schlageter, Michèle Souyri, Stéphane Giraudier, Jean-Jacques Kiladjian, Christine Chomienne, Bruno Cassinat
Abstract
Diamond-Blackfan anemia syndrome (DBA) is a ribosomopathy associated with loss-of-function variants in more than 20 ribosomal protein (RP) genes. Here, we report the genetic, functional and biochemical dissection of two multigenerational pedigrees with variants in RPL17, a large ribosomal subunit protein-encoding gene. Affected individuals had clinical features and erythroid proliferation defects consistent with DBA. Furthermore, RPL17/uL22 depletion resulted in anemia and micrognathia in zebrafish larvae, and in vivo complementation studies indicated that RPL17 variants were pathogenic. Lymphoblastoid cell lines (LCLs) derived from patients displayed a ribosomal RNA maturation defect reflecting haploinsufficiency of RPL17. The proteins encoded by RPL17 variants were not incorporated into ribosomes, but 10-20% of 60S ribosomal subunits contained a short form of 5.8S rRNA (5.8SC), a species that is marginal in normal cells. These atypical 60S subunits were actively engaged in translation. Ribosome profiling showed changes of the translational profile, but those are similar to LCLs bearing RPS19 variants. These results link an additional RP gene to DBA. They show that ribosomes can be modified substantially by RPL17 haploinsufficiency, but support the paradigm that translation alterations in DBA are primarily related to insufficient ribosome production rather than to changes in ribosome structure or composition.
Authors
Florence Fellmann, Carol Saunders, Marie-Françoise O'Donohue, David W. Reid, Kelsey A. McFadden, Nathalie Montel-Lehry, Cong Yu, Mingyan Fang, Jianguo Zhang, Beryl Royer-Bertrand, Pietro Farinelli, Narjesse Karboul, Jason R. Willer, Lorraine Fievet, Zahurul Alam Bhuiyan, Alissa L.W. Kleinhenz, Julie Jadeau, Joy Fulbright, Carlo Rivolta, Raffaele Renella, Nicholas Katsanis, Jacques S. Beckmann, Christopher V. Nicchitta, Lydie Da Costa, Erica E. Davis, Pierre-Emmanuel Gleizes
Abstract
The most common subtype of lymphoma globally, diffuse large B-cell lymphoma (DLBCL) is a leading cause of cancer death in people with HIV (HIV+). The restructuring of the T-cell compartment due to HIV infection and antiretroviral therapy (ART) may have implications for modern treatment selection, but current understanding of these dynamic interactions is limited. Here, we investigated the T-cell response to DLBCL by sequencing the T-cell receptor (TCR) repertoire in a cohort of HIV-negative (HIV-), HIV+/ART-experienced and HIV+/ART-naïve DLBCL patients. HIV+/ART-naïve tumor TCR repertoires were more clonal and more distinct from each other than HIV- and HIV+/ART-experienced. Further, increased overlap between tumor and blood TCR repertoires was associated with improved survival and HIV/ART status. Our study describes TCR repertoire characteristics for the first time in an African DLBCL cohort and demonstrates contributions of HIV infection and ART exposure to the DLBCL TCR repertoire.
Authors
Sophia M. Roush, Jenny Coelho, Alexander M. Xu, Kaushik Puranam, Marriam Mponda, Edwards Kasonkanji, Maurice Mulenga, Tamiwe Tomoka, Jonathan Galeotti, Amy Brownlee, Hormas Ghadially, Maganizo Chagomerana, Blossom Damania, Matthew Painschab, Akil Merchant, Satish Gopal, Yuri Fedoriw
Abstract
This study lays the groundwork for future lentivirus-mediated gene therapy in patients with Diamond Blackfan anemia (DBA) caused by mutations in ribosomal protein S19 (RPS19), showing evidence of a new safe and effective therapy. The data show that, unlike patients with Fanconi anemia (FA), the hematopoietic stem cell (HSC) reservoir of patients with DBA was not significantly reduced, suggesting that collection of these cells should not constitute a remarkable restriction for DBA gene therapy. Subsequently, 2 clinically applicable lentiviral vectors were developed. In the former lentiviral vector, PGK.CoRPS19 LV, a codon-optimized version of RPS19 was driven by the phosphoglycerate kinase promoter (PGK) already used in different gene therapy trials, including FA gene therapy. In the latter one, EF1α.CoRPS19 LV, RPS19 expression was driven by the elongation factor alpha short promoter, EF1α(s). Preclinical experiments showed that transduction of DBA patient CD34+ cells with the PGK.CoRPS19 LV restored erythroid differentiation, and demonstrated the long-term repopulating properties of corrected DBA CD34+ cells, providing evidence of improved erythroid maturation. Concomitantly, long-term restoration of ribosomal biogenesis was verified using a potentially novel method applicable to patients’ blood cells, based on ribosomal RNA methylation analyses. Finally, in vivo safety studies and proviral insertion site analyses showed that lentivirus-mediated gene therapy was nontoxic.
Authors
Yari Giménez, Manuel Palacios, Rebeca Sánchez-Domínguez, Christiane Zorbas, Jorge Peral, Alexander Puzik, Laura Ugalde, Omaira Alberquilla, Mariela Villanueva, Paula Río, Eva Gálvez, Lydie Da Costa, Marion Strullu, Albert Catala, Anna Ruiz-Llobet, Jose Carlos Segovia, Julián Sevilla, Brigitte Strahm, Charlotte M. Niemeyer, Cristina Beléndez, Thierry Leblanc, Denis L.J. Lafontaine, Juan Bueren, Susana Navarro
Abstract
Multiple myeloma is a largely incurable and life-threatening malignancy of antibody-secreting plasma cells. An effective and widely available animal model that recapitulates human myeloma and related plasma cell disorders is lacking. We show that busulfan-conditioned hIL-6 transgenic NSG mice (NSG+hIL6) reliably support the engraftment of malignant and pre-malignant human plasma cells including from patients diagnosed with monoclonal gammopathy of undetermined significance, pre- and post-relapse myeloma, plasma cell leukemia, and AL amyloidosis. Consistent with human disease, NSG+hIL6 mice engrafted with patient-derived myeloma cells, developed serum M spikes, and a majority developed anemia, hypercalcemia, and/or bone lesions. Single cell RNA sequencing showed non-malignant and malignant cell engraftment, the latter expressing a wide array of mRNAs associated with myeloma cell survival and proliferation. Myeloma engrafted mice given CAR T-cells targeting plasma cells or bortezomib experienced reduced tumor burden. Our results established NSG+hIL6 mice as an effective patient derived xenograft model for study and preclinical drug development of multiple myeloma and related plasma cell disorders.
Authors
Zainul S. Hasanali, Alfred L. Garfall, Lisa Burzenski, Leonard D. Shultz, Yan Tang, Siddhant Kadu, Neil C. Sheppard, Wei Liu, Derek Dopkin, Dan T. Vogl, Adam D. Cohen, Adam J. Waxman, Sandra P. Susanibar-Adaniya, Martin Carroll, Edward A. Stadtmauer, David Allman
Abstract
Thrombosis and inflammation are intimately linked and synergistically contribute to the pathogenesis of numerous thromboinflammatory diseases, including sickle cell disease (SCD). While platelets are central to thrombogenesis and inflammation, the molecular mechanisms of crosstalk between the 2 remain elusive. High-mobility group box 1 (HMGB1) regulates inflammation and stimulates platelet activation through Toll-like receptor 4. However, it remains unclear whether HMGB1 modulates other thrombotic agonists to regulate platelet activation. Herein, using human platelets, we demonstrate that HMGB1 significantly enhanced ADP-mediated platelet activation. Furthermore, inhibition of the purinergic receptor P2Y12 attenuated HMGB1-dependent platelet activation. Mechanistically, we show that HMGB1 stimulated ADP secretion, while concomitantly increasing P2Y12 levels at the platelet membrane. We show that in SCD patients, increased plasma HMGB1 levels were associated with heightened platelet activation and surface P2Y12 expression. Treatment of healthy platelets with plasma from SCD patients enhanced platelet activation and surface P2Y12, and increased sensitivity to ADP-mediated activation, and these effects were linked to plasma HMGB1. We conclude that HMGB1-mediated platelet activation involves ADP-dependent P2Y12 signaling, and HMGB1 primes platelets for ADP signaling. This complementary agonism between ADP and HMGB1 furthers the understanding of thromboinflammatory signaling in conditions such as SCD, and provides insight for therapeutic P2Y12 inhibition.
Authors
Deirdre Nolfi-Donegan, Gowtham K. Annarapu, Claudette St. Croix, Michael Calderon, Cheryl A. Hillery, Sruti Shiva
Abstract
Plasma cell-free DNA (cfDNA), a marker of disease severity in sepsis, is a recognized driver of thromboinflammation and a potential therapeutic target. In sepsis, plasma cfDNA is mostly derived from neutrophil extracellular trap (NET) degradation. Proposed NET-directed therapeutic strategies include preventing NET formation or accelerating NET degradation. However, NET digestion liberates pathogens and releases cfDNA that promote thrombosis and endothelial cell injury. We propose an alternative strategy of cfDNA and NET stabilization with chemokine platelet factor 4 (PF4, CXCL4). We previously showed that human PF4 (hPF4) enhances NET-mediated microbial entrapment. We now show that hPF4 interferes with thrombogenicity of cfDNA and NETs by preventing their cleavage to short-fragment and single-stranded cfDNA that more effectively activates the contact pathway of coagulation. In vitro, hPF4 also inhibits cfDNA-induced endothelial tissue factor surface expression and von Willebrand factor release. In vivo, hPF4 expression reduced plasma thrombin-antithrombin (TAT) levels in animals infused with exogenous cfDNA. Following lipopolysaccharide challenge, Cxcl4–/– mice had significant elevation in plasma TAT, cfDNA, and cystatin C levels, effects prevented by hPF4 infusion. These results show that hPF4 interacts with cfDNA and NETs to limit thrombosis and endothelial injury, an observation of potential clinical benefit in the treatment of sepsis.
Authors
Anh T.P. Ngo, Abigail Skidmore, Jenna Oberg, Irene Yarovoi, Amrita Sarkar, Nate Levine, Veronica Bochenek, Guohua Zhao, Lubica Rauova, M. Anna Kowalska, Kaitlyn Eckart, Nilam S. Mangalmurti, Ann Rux, Douglas B. Cines, Mortimer Poncz, Kandace Gollomp
Abstract
Patients with Down syndrome (DS, trisomy 21, T21) are at increased risk of transient abnormal myelopoiesis (TAM) and acute megakaryoblastic leukemia (ML-DS). Both TAM and ML-DS require prenatal somatic mutations in GATA1, resulting in the truncated isoform GATA1s. The mechanism by which individual chromosome 21 (HSA21) genes synergize with GATA1s for leukemic transformation is challenging to study, in part due to limited human cell models with wild type GATA1 or GATA1s. HSA21-encoded DYRK1A is overexpressed in ML-DS and may be a therapeutic target. To determine how DYRK1A influences hematopoiesis in concert with GATA1s, we used gene editing to disrupt all 3 alleles of DYRK1A in isogenic T21 induced pluripotent stem cells (iPSCs) with and without the GATA1s mutation. Unexpectedly, hematopoietic differentiation revealed that DYRK1A loss combined with GATA1s leads to increased megakaryocyte proliferation and decreased maturation. This proliferative phenotype was associated with upregulation of D-type cyclins and hyperphosphorylation of Rb to allow E2F release and de-repression of its downstream targets. Notably, DYRK1A loss had no effect in T21/wtGATA1 megakaryocytes. These surprising results suggest that DYRK1A and GATA1 may synergistically restrain megakaryocyte proliferation in Trisomy 21 and that DYRK1A inhibition may not be a therapeutic option for GATA1s-associated leukemias.
Authors
Ying Ting Sit, Kaoru Takasaki, Hyun Hyung An, Yan Xiao, Christian Hurtz, Peter Gearhart, Zhe Zhang, Paul Gadue, Deborah French, Stella T. Chou
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