Immunosuppression by Mutated Calreticulin Released from Malignant Cells

Liu, Peng; Zhao, Lu; Loos, Friedemann; Marty, Caroline; Xie, Wei; Martins, Isabelle; Lachkar, Sylvie; Qu, Bo; Waeckel-Énée, Emmanuelle; Plo, Isabelle; Vainchenker, William; Perez, Franck; Rodrı́guez, David; López-Otı́n, Carlos; Endert, Peter van; Zitvogel, Laurence; Kepp, Oliver

doi:10.1016/j.molcel.2019.11.004

Cited by 85 publications

(116 citation statements)

References 49 publications

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“…b To investigate the effect of CALR del52 and CALR ins5 on HSCs we engrafted different ratios of homozygous del52/del52 (yellow, pink, red, brown and black squares and solid lines) and ins5/ins5 (turquoise, blue, green, dark blue and black squares with solid lines) CD45. that CALR del52 has an immunosuppressive effect 23 and causes a down-regulation of MHC-I endogenous antigen loading and presentation 24 but CALR mutant epitopes were also shown to stimulate CD4 + and CD8 + T cells in patients 25,26 . Importantly, in contrast to JAK2 V617F , which is detected at a low level in lymphoid cells and rarely in T lymphocytes from MPN patients,…”

Section: Discussionmentioning

confidence: 99%

Calreticulin del52 and ins5 knock-in mice recapitulate different myeloproliferative phenotypes observed in patients with MPN

et al. 2020

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Somatic mutations in the calreticulin (CALR) gene are associated with approximately 30% of essential thrombocythemia (ET) and primary myelofibrosis (PMF). CALR mutations, including the two most frequent 52 bp deletion (del52) and 5 bp insertion (ins5), induce a frameshift to the same alternative reading frame generating new C-terminal tails. In patients, del52 and ins5 induce two phenotypically distinct myeloproliferative neoplasms (MPNs). They are equally found in ET, but del52 is more frequent in PMF. We generated heterozygous and homozygous conditional inducible knock-in (KI) mice expressing a chimeric murine CALR del52 or ins5 with the human mutated C-terminal tail to investigate their pathogenic effects on hematopoiesis. Del52 induces greater phenotypic changes than ins5 including thrombocytosis, leukocytosis, splenomegaly, bone marrow hypocellularity, megakaryocytic lineage amplification, expansion and competitive advantage of the hematopoietic stem cell compartment. Homozygosity amplifies these features, suggesting a distinct contribution of homozygous clones to human MPNs. Moreover, homozygous del52 KI mice display features of a penetrant myelofibrosis-like disorder with extramedullary hematopoiesis linked to splenomegaly, megakaryocyte hyperplasia and the presence of reticulin fibers. Overall, modeling del52 and ins5 mutations in mice successfully recapitulates the differences in phenotypes observed in patients.

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Section: Discussionmentioning

confidence: 99%

Calreticulin del52 and ins5 knock-in mice recapitulate different myeloproliferative phenotypes observed in patients with MPN

et al. 2020

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“…The authors proposed that full-length mutant CALR released from mutant cells into the supernatant is the factor responsible for the enhanced release of monocyte-derived immunosuppressive factors [81]. In concert with these findings are recently published data showing that CALR mutations may abrogate the effect of immunogenic cell death (ICD) [82]. ICD is a process where dying cells express prophagocytic surface molecules, one of the most important being CALR, thereby enhancing the DC-mediated phagocytosis of the cells, which allows for the more effective priming of T cells specific for antigens in the dying cell [83].…”

Section: Immunosuppressive Mechanisms Directly Mediated By Jak2v617f mentioning

confidence: 96%

Cancer Immune Therapy for Philadelphia Chromosome-Negative Chronic Myeloproliferative Neoplasms

Holmström

Hasselbalch

Andersen

2020

Cancers

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Philadelphia chromosome-negative chronic myeloproliferative neoplasms (MPN) are neoplastic diseases of the hematopoietic stem cells in the bone marrow. MPN are characterized by chronic inflammation and immune dysregulation. Of interest, the potent immunostimulatory cytokine interferon-α has been used to treat MPN for decades. A deeper understanding of the anti-cancer immune response and of the different immune regulatory mechanisms in patients with MPN has paved the way for an increased perception of the potential of cancer immunotherapy in MPN. Therapeutic vaccination targeting the driver mutations in MPN is one recently described potential new treatment modality. Furthermore, T cells can directly react against regulatory immune cells because they recognize proteins like arginase and programmed death ligand 1 (PD-L1). Therapeutic vaccination with arginase or PD-L1 therefore offers a novel way to directly affect immune inhibitory pathways, potentially altering tolerance to tumor antigens like mutant CALR and mutant JAK2. Other therapeutic options that could be used in concert with therapeutic cancer vaccines are immune checkpoint–blocking antibodies and interferon-α. For more advanced MPN, adoptive cellular therapy is a potential option that needs more preclinical investigation. In this review, we summarize current knowledge about the immune system in MPN and discuss the many opportunities for anti-cancer immunotherapy in patients with MPN.

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“…However, two distinct CRT bands were not readily detectable with anti-CRT(N) in lysates from MPN patient platelets ( Figure 1B and Figure S2A and S2B, middle panels, except possibly for the most highly expressed samples such as 2648-2), indicating that the detected protein corresponds to CRT WT . The C-terminal frameshift in all MPN mutant CRT results in a loss of the ER retention KDEL motif, causing their secretion from cells (29)(30)(31)(32) and indeed the mutants but not wild type CRT are detectable in patient serum by co-immunoprecipitation analyses ( Figure 1D). Enhanced secretion is expected to render all MPN CRT mutants more difficult to detect than the wild type CRT using generic anti-CRT antibodies in platelet lysates.…”

Section: Mutant Crts Form Disulfide-stabilized Multimers In Mpn Patiementioning

confidence: 99%

Mpl is activated by dimers of MPN-linked calreticulin mutants stabilized by disulfide bonds and ionic interactions

Venkatesan

Geng

Kandarpa

et al. 2020

Preprint

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Myeloproliferative neoplasms (MPNs) are frequently driven by insertions and deletions within the gene encoding calreticulin (CRT). CRTDel52 and CRTIns5 are recurrent mutations. Although oncogenic transformation requires both mutated CRT and the myeloproliferative leukemia protein (Mpl), the molecular mechanism of CRT-mediated constitutive activation of Mpl is unknown. Our studies reveal that the novel C-domain of CRTDel52 encodes specificity both for Mpl binding and for disulfide-mediated CRT dimerization. Disulfide-stabilized CRTDel52 dimers and multimers are observed in MPN patient-derived platelet lysates and in transfected mammalian cells. Cysteine mutations within both the novel C-domain (C400A and C404A) and the conserved N-domain (C163A) of CRTDel52 are required to reduce disulfide-mediated dimers and multimers of CRTDel52. Based on these data and published structures of crystalized CRT oligomers, we tested the relevance of ionic interactions between charged residues proximal to C163 at the N-domain dimerization interface. Charge alteration at these residues affected dimerization and multimerization of both wild type and CRTDel52. Elimination of intermolecular disulfides and disruption of ionic interactions at both proposed dimerization interfaces was required to abrogate the ability of CRTDel52 to induce cytokine-independent cell proliferation via Mpl. Based on these findings, we propose a structural model of the Mpl-activating CRTDel52 unit as a covalently-linked dimer that is stabilized by disulfides and ionic interactions at both the C-domain and N-domain. MPNs exploit a natural dimerization interface of CRT combined with C-domain gain-of-functions to achieve cell transformation.

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Immunosuppression by Mutated Calreticulin Released from Malignant Cells

Abstract: Highlights d Exon-9-mutated CALR is released from cells in vitro and in vivo d Extracellular CALR inhibits the phagocytosis of dying cancer cells by dendritic cells d Immunosuppressive effects of mutated CALR blunt responses to anticancer immunotherapy

Cited by 85 publications

References 49 publications

Calreticulin del52 and ins5 knock-in mice recapitulate different myeloproliferative phenotypes observed in patients with MPN

Calreticulin del52 and ins5 knock-in mice recapitulate different myeloproliferative phenotypes observed in patients with MPN

Cancer Immune Therapy for Philadelphia Chromosome-Negative Chronic Myeloproliferative Neoplasms

Mpl is activated by dimers of MPN-linked calreticulin mutants stabilized by disulfide bonds and ionic interactions

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