PRAME is a prominent member of the cancer germline antigen family of proteins, which triggers autologous T-cell mediated immune responses. Integrative genomic analysis in diffuse large B-cell lymphoma (DLBCL) uncovered recurrent, and highly focal deletions of 22q11.22 including the PRAME gene, which were associated with poor outcome. PRAME-deleted tumors showed cytotoxic T-cell immune escape and were associated with cold tumor microenvironments. In addition, PRAME down-modulation was strongly associated with somatic EZH2 Y641 mutations in DLBCL. In turn, PRC2-regulated genes were repressed in isogenic PRAME KO lymphoma cell lines and PRAME was found to directly interact with EZH2 as a negative regulator. EZH2 inhibition with EPZ-6438 abrogated these extrinsic and intrinsic effects leading to PRAME expression and microenvironment restoration in vivo. Our data highlight multiple functions of PRAME during lymphomagenesis, and provide a preclinical rationale for synergistic therapies combining epigenetic re-programming with PRAME-targeted therapies.
Katsuyoshi Takata, Lauren C. Chong, Daisuke Ennishi, Tomohiro Aoki, Michael Yu Li, Avinash Thakur, Shannon Healy, Elena Viganò, Tao Dao, Daniel Kwon, Gerben Duns, Julie S. Nielsen, Susana Ben-Neriah, Ethan Tse, Stacy S. Hung, Merrill Boyle, Sung Soo Mun, Christopher M. Bourne, Bruce Woolcock, Adèle H. Telenius, Makoto Kishida, Shinya Rai, Allen W. Zhang, Ali Bashashati, Saeed Saberi, Gianluca D' Antonio, Brad H. Nelson, Sohrab P. Shah, Pamela A. Hoodless, Ari M. Melnick, Randy D. Gascoyne, Joseph M. Connors, David A. Scheinberg, Wendy Béguelin, David W. Scott, Christian Steidl
Ischemic stroke prompts a strong inflammatory response which is associated with exacerbated outcomes. In this study, we investigated mechanistic regulators of neutrophil extracellular trap (NET) formation in stroke and if they contribute to stroke outcomes. NET forming neutrophils were found throughout brain tissue of ischemic stroke patients and elevated plasma NET biomarkers correlated with worse stroke outcomes. Additionally, we observed increased plasma and platelet surface expressed high mobility group box 1 (HMGB1) in stroke patients. Mechanistically, platelets were identified as the critical source for HMGB1 causing NETs in the acute phase of stroke. Depleting platelets or platelet-specific knockout of HMGB1 significantly reduced plasma HMGB1 and NET levels after stroke, and greatly improved stroke outcomes. We subsequently investigated the therapeutic potential of neonatal NET inhibitory factor (nNIF) in stroke. Mice treated with nNIF had smaller brain infarcts, improved long-term neurological and motor function, and enhanced survival after stroke. nNIF specifically blocked NET formation without affecting neutrophil recruitment after stroke. Importantly, nNIF also improved stroke outcomes in diabetic and aged mice and was still effective when given 1 hour after stroke onset. These results support a pathological role for NETs in ischemic stroke and warrant further investigation of nNIF for stroke therapy.
Frederik Denorme, Irina Portier, John L. Rustad, Mark J. Cody, Claudia V. de Araujo, Chieko Hoki, Matthew D. Alexander, Ramesh Grandhi, Mitchell R. Dyer, Matthew D. Neal, Jennifer J. Majersik, Christian C. Yost, Robert A. Campbell
Platelets have a wide range of functions including critical roles in hemostasis, thrombosis, and immunity. We hypothesized that during acute inflammation, such as in life-threatening sepsis, there are fundamental changes in the sites of platelet production and phenotypes of resultant platelets. Here, we showed during sepsis that the spleen is a major site of megakaryopoiesis and platelet production. Sepsis provoked an adrenergic-dependent mobilization of megakaryocyte-erythrocyte progenitors (MEPs) from the bone marrow to the spleen where interleukin-3 (IL-3) induced their differentiation into megakaryocytes. In the spleen, immune-skewed megakaryocytes produced a CD40 ligand-high platelet population with potent immunomodulatory functions. Transfusions of post-sepsis platelets enriched from splenic production enhanced immune responses and reduced overall mortality in sepsis-challenged animals. These findings identify a spleen-derived protective platelet population that may be broadly immunomodulatory in acute inflammatory states such as sepsis.
Colin Valet, Mélia Magnen, Longhui Qiu, Simon J. Cleary, Kristin M. Wang, Serena Ranucci, Elodie Grockowiak, Rafik Boudra, Catharina Conrad, Yurim Seo, Daniel R. Calabrese, John R. Greenland, Andrew D. Leavitt, Emmanuelle Passegué, Simon Mendez-Ferrer, Filip K. Swirski, Mark R. Looney
The chromosomal t(4;14) (p16;q32) translocation drives high expression of histone methyltransferase nuclear SET domain–containing 2 (NSD2) and plays vital roles in multiple myeloma (MM) evolution and progression. However, the mechanisms of NSD2-driven epigenomic alterations in chemoresistance to proteasome inhibitors (PIs) are not fully understood. Using a CRISPR/Cas9 sgRNA library in a bone marrow–bearing MM model, we found that hepatoma-derived growth factor 2 (HRP2) was a suppressor of chemoresistance to PIs and that its downregulation correlated with a poor response and worse outcomes in the clinic. We observed suppression of HRP2 in bortezomib-resistant MM cells, and knockdown of HRP2 induced a marked tolerance to PIs. Moreover, knockdown of HRP2 augmented H3K27me3 levels, consequentially intensifying transcriptome alterations promoting cell survival and restriction of ER stress. Mechanistically, HRP2 recognized H3K36me2 and recruited the histone demethylase MYC-induced nuclear antigen (MINA) to remove H3K27me3. Tazemetostat, a highly selective epigenetic inhibitor that reduces H3K27me3 levels, synergistically sensitized the anti-MM effects of bortezomib both in vitro and in vivo. Collectively, these results provide a better understanding of the origin of chemoresistance in patients with MM with the t(4;14) translocation and a rationale for managing patients with MM who have different genomic backgrounds.
Jingjing Wang, Xu Zhu, Lin Dang, Hongmei Jiang, Ying Xie, Xin Li, Jing Guo, Yixuan Wang, Ziyi Peng, Mengqi Wang, Jingya Wang, Sheng Wang, Qian Li, Yafei Wang, Qiang Wang, Lingqun Ye, Lirong Zhang, Zhiqiang Liu
Eltrombopag, an FDA-approved non-peptidyl thrombopoietin receptor agonist is clinically used for the treatment of aplastic anemia, a disease characterized by hematopoietic stem cell failure and pancytopenia, to improve platelet counts and stem cell function. Eltrombopag treatment results in durable tri-lineage hematopoietic expansion in patients. Some of the eltrombopag hematopoietic activity has been attributed to its off-target effects including its iron chelation properties. However, eltrombopag mechanism of action is still poorly understood with respect to its full spectrum of clinical effects. Here, we report that eltrombopag bound to the TET2 catalytic domain and inhibited its dioxygenase activity, which was independent of its iron chelating activity. The DNA demethylating enzyme TET2, essential for hematopoietic stem cell differentiation and lineage commitment, is frequently mutated in myeloid malignancies. Eltrombopag treatment expanded TET proficient normal hematopoietic stem and progenitor cells, in part, due to its ability to mimic loss of TET2 with simultaneous thrombopoietin receptor activation. On the contrary, TET inhibition in TET2 mutant malignant myeloid cells prevented neoplastic clonal evolution, in vitro and in vivo. This new mechanism of action may offer a restorative therapeutic index and provide a scientific rationale to treat selected patients with TET2-mutant or TET deficiency associated myeloid malignancies.
Yihong Guan, Metis Hasipek, Dongxu Jiang, Anand D. Tiwari, Dale R. Grabowski, Simona Pagliuca, Sunisa Kongkiatkamon, Bhumika Patel, Salendra Singh, Yvonne Parker, Thomas LaFramboise, Daniel Lindner, Mikkael A. Sekeres, Omar Y. Mian, Yogen Saunthararajah, Jaroslaw P. Maciejewski, Babal K. Jha
The bone marrow (BM) microenvironment regulates acute myeloid leukemia (AML) initiation, proliferation and chemotherapy resistance. Following cancer cell death, a growing body of evidence suggests an important role for remaining apoptotic debris in regulating the immunologic response to, and growth of, solid tumors. Here we investigated the role of macrophage LC3-associated phagocytosis (LAP) within the BM microenvironment of AML. Depletion of BM macrophages increased AML growth in-vivo. We showed that LAP is the predominate method of BM macrophage phagocytosis of dead and dying cells in the AML microenvironment. Targeted inhibition of LAP led to accumulation of apoptotic cells (AC) and apoptotic bodies (AB) resulting in accelerated leukemia growth. Mechanistically, LAP of AMLderived-AB by BM macrophages, resulted in STING pathway activation. We identified that AML derived mitochondrial damage associated molecular patterns were processed by BM macrophages via LAP. Moreover, depletion of mitochondrial DNA (mtDNA) in AML derived-AB showed that it is this mtDNA which was responsible for the induction of STING signalling in BM macrophages. Phenotypically we found that STING activation suppressed AML growth through a mechanism related to increased phagocytosis. In summary, we report that macrophage LAP of apoptotic debris in the AML BM microenvironment suppressed tumor growth.
Jamie A. Moore, Jayna J. Mistry, Charlotte Hellmich, Rebecca H. Horton, Edyta E. Wojtowicz, Aisha Jibril, Matthew Jefferson, Thomas Wileman, Naiara Beraza, Kristian M. Bowles, Stuart A. Rushworth
BACKGROUND. Curative gene therapies for sickle cell disease (SCD) are currently undergoing clinical evaluation. The occurrence of myeloid malignancies in these trials has prompted safety concerns. Individuals with SCD are predisposed to myeloid malignancies, but the underlying causes remain undefined. Clonal hematopoiesis (CH) is a pre-malignant condition that also confers significant predisposition to myeloid cancers. While it has been speculated that CH may play a role in SCD-associated cancer predisposition, limited data addressing this issue have been reported. METHODS. Here, we leveraged 74,190 whole genome sequences to robustly study CH in SCD. Somatic mutation calling methods were used to assess CH in all samples and comparisons between individuals with and without SCD were performed. RESULTS. While we had sufficient power to detect a greater than 2-fold increased rate of CH, we found no detectable variation in rate or clone properties between individuals affected by SCD and controls. The rate of CH in individuals with SCD was unaltered by hydroxyurea use. CONCLUSIONS. We did not observe an increased risk for acquiring detectable CH in SCD, at least as measured by whole genome sequencing. These results should help guide ongoing efforts and further studies that seek to better define the risk factors underlying myeloid malignancy predisposition in SCD and help ensure that curative therapies can be more safely applied.FUNDING. Funding was provided by the New York Stem Cell Foundation and National Institutes of Health. The funders had no role in study design or reporting.
L. Alexander Liggett, Liam D. Cato, Joshua S. Weinstock, Yingze Zhang, S. Mehdi Nouraie, Mark T. Gladwin, Melanie E. Garrett, Allison Ashley-Koch, Marilyn Telen, Brian Custer, Shannon Kelly, Carla Dinardo, Ester C. Sabino, Paula Loureiro, Anna Carneiro-Proietti, Cláudia Maximo, Alexander P. Reiner, Gonçalo R. Abecasis, David A. Williams, Pradeep Natarajan, Alexander G. Bick, Vijay G. Sankaran
Somatic mutations in the spliceosome gene U2AF1 are common in patients with myelodysplastic syndromes. U2AF1 mutations that code for the most common amino acid substitutions are always heterozygous, and the retained wild-type allele is expressed, suggesting that mutant hematopoietic cells may require the residual wild-type allele to be viable. We show that hematopoiesis and RNA splicing in U2af1 heterozygous knock-out mice was similar to control mice, but that deletion of the wild-type allele in U2AF1(S34F) heterozygous mutant expressing hematopoietic cells (i.e., hemizygous mutant) was lethal. These results confirm that U2AF1 mutant hematopoietic cells are dependent on the expression of wild-type U2AF1 for survival in vivo and that U2AF1 is a haplo-essential cancer gene. Mutant U2AF1 (S34F) expressing cells were also more sensitive to reduced expression of wild-type U2AF1 than non-mutant cells. Furthermore, mice transplanted with leukemia cells expressing mutant U2AF1 had significantly reduced tumor burden and improved survival after the wild-type U2af1 allele was deleted compared to when it was not deleted. These results suggest that selectively targeting the wild-type U2AF1 allele in heterozygous mutant cells could induce cancer cell death and be a therapeutic strategy for patients harboring U2AF1 mutations.
Brian A. Wadugu, Sridhar Nonavinkere Srivatsan, Amanda Heard, Michael O. Alberti, Matthew Ndonwi, Jie Liu, Sarah Grieb, Joseph Bradley, Jin Shao, Tanzir Ahmed, Cara L. Shirai, Ajay Khanna, Dennis L. Fei, Christopher A. Miller, Timothy A. Graubert, Matthew J. Walter
Multiple myeloma (MM), a terminally differentiated B-cell malignancy, remains difficult to cure. Understanding the molecular mechanisms underlying the progression of MM may identify therapeutic targets and lead to a fundamental shift in treatment of the disease. Deubiquitination like ubiquitination is a highly regulated process, implicated in almost every cellular process. Multiple deubiquitinating enzymes (DUBs) have been identified but their regulation is poorly defined. Here, we determined that TRIP13 increases cellular deubiquitination. Overexpression of TRIP13 in mice and cultured cells resulted in excess cellular deubiquitination by enhancing the association of the DUB USP7 with its substrates. We show that TRIP13 is an oncogenic protein because it accelerates B-cell tumor development in transgenic mice. TRIP13-induced resistance to proteasome inhibition can be overcome by a USP7 inhibitor in vitro and in vivo. These findings point to a critical role for TRIP13 expression in B-cell lymphoma and MM by governing deubiquitination of critical oncogenic (NEK2) and tumor suppressor (PTEN, P53) proteins. High TRIP13 identifies a high-risk patient group amendable to adjuvant anti-USP7 therapy.
Can Li, Jiliang Xia, Reinaldo Franqui Machin, Fangping Chen, Yanjuan He, Timothy Cody Ashby, Feixiang Teng, Hongwei Xu, Dingxiao Liu, Dongzheng Gai, Sarah K. Johnson, Frits van Rhee, Siegfried Janz, John D. Shaughnessy Jr, Guido Tricot, Ivana Frech, Fenghuang Zhan
Peripheral T-cell lymphomas (PTCLs) represent a significant unmet medical need with dismal clinical outcome. T-cell receptor (TCR) is emerging as a key driver of T lymphocytes transformation. However, the role of chronic TCR activation in lymphomagenesis and in survival of lymphoma cells is still poorly understood. Using an original mouse model, we report here that chronic TCR stimulation drives T-cell lymphomagenesis whereas TCR signaling does not contribute to PTCL survival. The combination of kinome, transcriptome and epigenome analyses of mouse PTCLs revealed a NK-like reprogramming of PTCL cells with expression of NK receptors (NKRs) and downstream signaling molecules such as Tyrobp and Syk. Activating NKR were functional in PTCLs and dependent of Syk activity. In vivo blockade of NKR signaling prolonged mouse survival, demonstrating the addiction of PTCLs to NKR and downstream Syk/mTOR activity for their survival. Studying a large collection of human primary samples, we identified several PTCLs recapitulating the phenotype described in this model by expressing NKR and Syk, suggesting similar mechanism of lymphomagenesis and establishing rationales for clinical trials targeting such molecules.
Sylvain Carras, Dimitri Chartoire, Sylvain Mareschal, Maël Heiblig, Antoine Marçais, Rémy Robinot, Mirjam Urb, Roxane M. Pommier, Edith Julia, Amel Chebel, Aurélie Verney, Charlotte Bertheau, Emilie Bardel, Caroline Fezelot, Lucien Courtois, Camille Lours, Alyssa Bouska, Sunandini Sharma, Christine Lefebvre, Jean-Pierre Rouault, David Sibon, Anthony Ferrari, Javeed Iqbal, Laurence de Leval, Philippe Gaulard, Alexandra Traverse-Glehen, Pierre Sujobert, Mathieu Bléry, Gilles Salles, Thierry Walzer, Emmanuel Bachy, Laurent Genestier