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
Myelofibrosis (MF) are a non-BCR-ABL myeloproliferative neoplasms (NMPs) associated with poor outcomes. Current treatment has little effect on the natural history of the disease. MF results from complex interactions between 1) the malignant clone, 2) an inflammatory context, and 3) remodeling of the bone marrow (BM) microenvironment. Each of these points is a potential target of PPAR-y activation. Here, we demonstrated the therapeutic potential of PPAR-y agonists in resolving MF in three mouse models. We showed that PPAR-y agonists reduce myeloproliferation, modulate inflammation, and protect the BM stroma in vitro and ex vivo. Activation of PPAR-y constitutes a relevant therapeutic target in MF and our data support the possibility of using PPAR-y agonists in clinical practice.
Juliette Lambert, Joseph Saliba, Carolina Calderon, Karine Sii-Felice, Mohammad Salma, Valérie Edmond, Jean-Claude Alvarez, Marc Delord, Caroline Marty, Isabelle Plo, Jean-Jacques Kiladjian, Eric Soler, William Vainchenker, Jean-Luc Villeval, Philippe Rousselot, Stephane Prost
Anemia in β-thalassemia is related to ineffective erythropoiesis and reduced red cell survival. Excess free heme and accumulation of unpaired α-globin chains impose substantial oxidative stress on β-thalassemic erythroblasts and erythrocytes, impacting cell metabolism. We hypothesized that increased pyruvate kinase activity induced by mitapivat (AG-348) in the Hbbth3/+ mouse model for β-thalassemia would reduce chronic hemolysis and ineffective erythropoiesis through stimulation of red cell glycolytic metabolism. Oral mitapivat administration ameliorated ineffective erythropoiesis and anemia in Hbbth3/+ mice. Increased ATP, reduced reactive oxygen species production, and reduced markers of mitochondrial dysfunction associated with improved mitochondrial clearance suggested enhanced metabolism following mitapivat administration in β-thalassemia. The amelioration of responsiveness to erythropoietin resulted in reduced soluble erythroferrone, increased liver Hamp expression, and diminished liver iron overload. Mitapivat reduced duodenal Dmt1 expression potentially by activating the pyruvate kinase M2HIF2α axis, representing a mechanism additional to Hamp in controlling iron absorption and preventing β-thalassemia–related liver iron overload. In ex vivo studies on erythroid precursors from patients with β-thalassemia, mitapivat enhanced erythropoiesis, promoted erythroid maturation, and decreased apoptosis. Overall, pyruvate kinase activation as a treatment modality for β-thalassemia in preclinical model systems had multiple beneficial effects in the erythropoietic compartment and beyond, providing a strong scientific basis for further clinical trials.
Alessandro Matte, Enrica Federti, Charles Kung, Penelope A. Kosinski, Rohini Narayanaswamy, Roberta Russo, Giorgia Federico, Francesca Carlomagno, Maria Andrea Desbats, Leonardo Salviati, Christophe Leboeuf, Maria Teresa Valenti, Francesco Turrini, Anne Janin, Shaoxia Yu, Elisabetta Beneduce, Sebastien Ronseaux, Iana Iatcenko, Lenny Dang, Tomas Ganz, Chun-Ling Jung, Achille Iolascon, Carlo Brugnara, Lucia De Franceschi
Inhibitors to factor VIII (FVIII) remain the most challenging complication of FVIII protein replacement therapy in hemophilia A (HA). Understanding the mechanisms that guide FVIII-specific B cell development could help identify therapeutic targets. The B cell activating factor (BAFF) cytokine family is a key regulator of B cell differentiation in normal homeostasis and immune disorders. Thus, we used patient samples and mouse models to investigate the potential role of BAFF in modulating FVIII inhibitors. BAFF levels were elevated in pediatric and adult HA inhibitor patients and decreased to levels similar to non-inhibitor controls after successful immune tolerance induction (ITI). Moreover, elevations in BAFF levels were seen in patients who failed to achieve FVIII tolerance with anti-CD20 mediated B-cell depletion. In naïve HA mice, prophylactic anti-BAFF therapy prior to FVIII immunization prevented inhibitors and this tolerance was maintained despite FVIII exposure after immune reconstitution. In preimmunized HA mice, combination therapy with anti-CD20 and anti-BAFF antibodies dramatically reduced FVIII inhibitors via inhibition of FVIII-specific plasma cells. Our data suggest that BAFF may regulate the generation and maintenance of FVIII inhibitors and/or anti-FVIII B cells. Finally, anti-CD20/anti-BAFF combination therapy may be clinically useful for ITI.
Bhavya S. Doshi, Jyoti Rana, Giancarlo Castaman, Mostafa A. Shaheen, Radoslaw Kaczmarek, John S. S. Butterfield, Shannon L. Meeks, Cindy Leissinger, Moanaro Biswas, Valder R. Arruda
In order to sustain proficient life-long hematopoiesis, hematopoietic stem cells (HSCs) must possess robust mechanisms to preserve their quiescence and genome integrity. DNA-damaging stress can perturb HSC homeostasis by affecting their survival, self-renewal and differentiation. Ablation of the kinase ATM, a master regulator of the DNA damage response, impairs HSC fitness. Paradoxically, we show here that loss of a single allele of Atm enhances HSC functionality in mice. To explain this observation, we explored a possible link between ATM and the tumor suppressor PTEN, which also regulates HSC function. We generated and analyzed a knock-in mouse line (PtenS398A/S398A), in which PTEN cannot be phosphorylated by ATM. Similar to Atm+/-, PtenS398A/S398A HSCs have enhanced hematopoietic reconstitution ability, accompanied by resistance to apoptosis induced by genotoxic stress. Single-cell transcriptomic analyses and functional assays revealed that dormant PtenS398A/S398A HSCs aberrantly tolerate elevated mitochondrial activity and the accumulation of reactive oxygen species, which are normally associated with HSC priming for self-renewal or differentiation. Our results unveil a molecular connection between ATM and PTEN, which couples the response to genotoxic stress and dormancy in HSC.
Jerome Fortin, Christian Bassi, Parameswaran Ramachandran, Wanda Y. Li, Ruxiao Tian, Ida Zarrabi, Graham Hill, Bryan E. Snow, Jillian Haight, Chantal Tobin, Kelsey Hodgson, Andrew Wakeham, Vuk Stambolic, Tak W. Mak
Bone marrow (BM) hematopoietic stem cells (HSCs) become dysfunctional during aging (i.e., they are increased in number but have an overall reduction in long-term repopulation potential and increased myeloid differentiation) compared with young HSCs, suggesting limited use of old donor BM cells for hematopoietic cell transplantation (HCT). BM cells reside in an in vivo hypoxic environment yet are evaluated after collection and processing in ambient air. We detected an increase in the number of both young and aged mouse BM HSCs collected and processed in 3% O2 compared with the number of young BM HSCs collected and processed in ambient air (~21% O2). Aged BM collected and processed under hypoxic conditions demonstrated enhanced engraftment capability during competitive transplantation analysis and contained more functional HSCs as determined by limiting dilution analysis. Importantly, the myeloid-to-lymphoid differentiation ratio of aged BM collected in 3% O2 was similar to that detected in young BM collected in ambient air or hypoxic conditions, consistent with the increased number of common lymphoid progenitors following collection under hypoxia. Enhanced functional activity and differentiation of old BM collected and processed in hypoxia correlated with reduced “stress” associated with ambient air BM collection and suggests that aged BM may be better and more efficiently used for HCT if collected and processed under hypoxia so that it is never exposed to ambient air O2.
Maegan L. Capitano, Safa F. Mohamad, Scott Cooper, Bin Guo, Xinxin Huang, Andrea M. Gunawan, Carol Sampson, James Ropa, Edward F. Srour, Christie M. Orschell, Hal E. Broxmeyer
Autosomal dominant "sterile alpha motif domain containing 9 (Samd9) and Samd9L (Samd9/9L) syndromes" are a large subgroup of currently established inherited bone marrow failure syndromes that include MIRAGE, ataxia pancytopenia, and familial monosomy 7 syndromes. Samd9/9L genes are located in tandem on chromosome 7 and have been known to be the genes responsible for myeloid malignancies associated with monosomy 7. Additionally, as interferon-inducible genes, Samd9/9L are crucial for protection against viruses. Samd9/9L syndromes are caused by gain-of-function mutations and develop into infantile myelodysplastic syndromes associated with monosomy 7 (MDS/-7) at extraordinarily high frequencies. We generated mice expressing Samd9LD764N, which mimic the MIRAGE syndrome presenting with growth retardation, a short life, bone marrow failure, and multi-organ degeneration. In hematopoietic cells, Samd9LD764N downregulates the endocytosis of transferrin and c-Kit resulting in a rare cause of anemia and a low bone marrow reconstitutive potential that ultimately causes MDS/-7. By contrast, in non-hematopoietic cells we tested, Samd9LD764N upregulated the endocytosis of EGFR by Ship2 phosphatase translocation to the cytomembrane and activated lysosomes, resulting in the reduced expression of surface receptors and signaling. Thus Samd9/9L is a downstream regulator of interferon that controls receptor metabolism, with constitutive activation leading to multi-organ dysfunction.
Akiko Nagamachi, Akinori Kanai, Megumi Nakamura, Hiroshi Okuda, Akihiko Yokoyama, Satoru Shinriki, Hirotaka Matsui, Toshiya Inaba
How particular bone marrow niche factors contribute to the leukemogenic activities of leukemia-initiating cells (LICs) remain largely unknown. Here, we showed that ATP levels were markedly increased in the bone marrow niches of mice with acute myeloid leukemia (AML), and LICs preferred to localizing to the endosteal niche with relatively high ATP levels, as indicated by a sensitive ATP indicator. ATP could efficiently induce the influx of ions into LICs in an MLL-AF9-induced murine AML model via the ligand-gated ion channel P2X7. P2x7 deletion led to notably impaired homing and self-renewal capacities of LICs and contributed to an ~5-fold decrease in the number of functional LICs but had no effect on normal hematopoiesis. ATP-P2X7 signaling enhanced the calcium flux-mediated phosphorylation of CREB, which further transactivated the Phgdh expression to maintain serine metabolism and LIC fates. P2X7-knockdown resulted in a markedly extended survival of recipients transplanted with either human AML cell lines or primary leukemia cells. Blockade of ATP-P2X7 signaling could efficiently inhibit leukemogenesis. Here, we provide a unique perspective for understanding how ATP-P2X7 signaling sustains the LIC activities, which may benefit the development of specific strategies for targeting LICs or other types of cancer stem cells
Xiaoxiao He, Jiangbo Wang, Xiaona Yang, Xiuze Zhang, Dan Huang, Xie Li, Yejun Zou, Chiqi Chen, Zhuo Yu, Li Xie, Yaping Zhang, Ligen Liu, Shangang Li, Yuzheng Zhao, Hongfang Shao, Ye Yu, Junke Zheng
Cutaneous T cell lymphoma (CTCL) has a poorly understood etiology and no cure. Using conditional knockout mice, we found that ablation of the genomic organizer Special AT-rich sequence-binding protein-1 (Satb1) caused malignant transformation of mature, skin-homing, Notch-activated CD4+ and CD8+ T-cells into progressively fatal lymphoma. Mechanistically, Satb1 restrained Stat5 phosphorylation and the expression of skin-homing chemokine receptors in mature T-cells. Notably, methyltransferase-dependent epigenetic repression of SATB1 was universally found in human Sézary syndrome, but not in other peripheral T-cell malignancies. H3K27 and H3K9 trimethylation occluded the SATB1 promoter in Sézary cells, while inhibition of SUV39H1/2 methyltransferases (unlike EZH2 inhibition), restored protective SATB1 expression and selectively abrogated the growth of primary Sézary cells more effectively than romidepsin. Therefore, inhibition of methyltransferases that silence SATB1 could address an unmet need for patients with Mycosis fungoides/Sézary syndrome, a set of incurable diseases.
Carly M. Harro, Jairo Perez-Sanz, Tara Lee Costich, Kyle K. Payne, Carmen M. Anadon Galindo, Ricardo A. Chaurio, Subir Biswas, Gunjan Mandal, Kristen E. Rigolizzo, Kimberly B. Sprenger, Jessica A. Mine, Louise Showe, Xiaoqing Yu, Kebin Liu, Paulo C. Rodriguez, Javier Pinilla-Ibarz, Lubomir Sokol, Jose R. Conejo-Garcia