Context Dependent Role of Polycomb Repressive Complex 2 in Acute Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 610-610
Author(s):  
Etienne Danis ◽  
Taylor Yamauchi ◽  
Kristen Echanique ◽  
Jessica Haladyna ◽  
Huafeng Xie ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
Acute Leukemia ◽  
Murine Models ◽  
Polycomb Repressive Complex ◽  
Cell Precursor ◽  
Polycomb Repressive Complex 2

Abstract Polycomb Repressive Complex 2 (PRC2) is a multi-protein complex with important roles in development and cancer. Both hyper- and hypoactivity of PRC2 are associated with blood-related malignancies. Activating mutations of the PRC2 methyltransferase EZH2 have been found in human B-lineage lymphomas. Inactivating mutations of PRC2 components EZH2, EED and SUZ12 have been described in early T-cell Precursor ALL (ETP-ALL) and inactivating PRC2-alterations are found in Myelodysplastic and Myeloproliferative Syndromes. The mechanisms underlying this paradox are incompletely understood. We here investigate the context dependent role of PRC2 in murine models. We initially studied PRC2 in normal hematopoiesis: Chip-seq analysis of the PRC2-mediated H3K27me3 chromatin mark demonstrates that many genes highly expressed in immature hematopoiesis gain H3K27me3 in the developmental transition from more immature Lin-Sca1+Kit+ (LSK) cells to lineage committed Granulocyte Macrophage Progenitors (GMPs). Transcription of these genes is enriched in EZH2ko GMP compared to EZH2ffGMP by Gene Set Enrichment Analysis (GSEA). These data suggest that PRC2 is important for the silencing of immature gene expression programs in the developmental transition from LSK to GMP. We next analyzed the role of PRC2 in two murine models of acute leukemia: MLL-AF9 driven leukemia, and a model of early T-cell precursor T-ALL (ETP-ALL). In MLL-AF9 leukemia, we previously found that inactivation of Eed completely abrogate leukemogenesis in vitro and in vivo. We now report that genetic inactivation of the tumor suppressor Cdkn2a (a canonical PRC2 target) partially rescued MLL-AF9 mediated leukemia in vitro and in vivo. However, Cdkn2akoEEDko MLL-AF9 leukemia remained compromised. In vitro growth was reduced to approximately 10% of Eedff controls. While control MLL-AF9 leukemia developed in vivo in 100% of the recipients, Cdkn2akoEEDkoMLL-AF9 leukemia developed with significantly prolonged latency and incomplete penetrance (25%). RNAseq analysis revealed that high level expression of genes with established roles in MLL-AF9 leukemia such as HoxA9, Cdk6 and Jmjd1c unexpectedly depends on Eed. These data are in keeping with the absence of alterations in PRC2-components in human MLL-rearranged leukemia. In contrast, PRC2 core components (EZH2/EED/SUZ12) are deleted or mutated in > 40% of ETP-ALL. ETP-ALL also often has direct or indirect activation of the RAS-pathway, and carries frequent deletions of the CDKN2A locus. To model the effects of EED and EZH2-inactivation in ETP-ALL, we established Cdkn2akoEedff vs Cdkn2akoEedko, and Cdkn2akoEzh2ff vs Cdkn2akoEZH2koleukemias by transduction with NRASQ61K followed by expansion on OP9DL1 stroma cells to activate T-lineage differentiation via Notch-signaling. Cdkn2ako NRASQ61K leukemia showed an immunophenotype similar to human ETP-ALL (positive for c-Kit, CD5 and myeloid markers and mostly negative for CD4/8). Inactivation of Eed or Ezh2 in this model led to a shortening of latency (p=0.03 for Eed, p=0.0001 for Ezh2). RNAseq revealed enrichment of genes associated with murine DN1 thymocytes and with human ETP-ALL in Eedko vs Eedff Cdkn2ako NRASQ61K leukemia. These genesets showed even more pronounced enrichment in Ezh2kocompared to Ezh2ff Cdkn2ako NRASQ61K leukemia. Genes highly expressed in early hematopoiesis were enriched in Eedko and Ezh2ko cells in both, the MLL-AF9 and NRASQ61K leukemia models. However, there was an opposing effect on HoxA9 gene expression, with PRC2 inactivation leading to decreased HoxA9 expression in MLL-AF9, and increased HoxA9 expression in Cdkn2ako NRASQ61K leukemia. Decreased HoxA9 has been shown to impair MLL-AF9 leukemia growth. To test the functional significance of elevated HoxA9-levels in the Eedko and EZH2koNRASQ61K leukemias, we co-expressed HoxA9 and NRASQ61K in the presence of intact Eed and Ezh2 loci. Preliminary data suggest that HoxA9 accelerates leukemia development in this setting. Alterations in chromatin modifiers, including PRC2, are frequent in leukemia and lymphoma. Our data demonstrate that manipulation of PRC2 can have opposite effects on leukemia phenotype and expression of key PRC2-repressed genes such as HoxA9 in the context of different tumors. We are currently characterizing the mechanisms leading to divergent outcomes of PRC2 manipulation in MLL-AF9 leukemia compared to NRASQ61K ETP-like leukemia. Disclosures Armstrong: Epizyme : Consultancy.

scholarly journals Signaling function of PRC2 is essential for TCR-driven T cell responses

2018 ◽  
Vol 215 (4) ◽  
pp. 1101-1113 ◽  
Author(s):  
Marc-Werner Dobenecker ◽  
Joon Seok Park ◽  
Jonas Marcello ◽  
Michael T. McCabe ◽  
Richard Gregory ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Therapeutic Potential ◽  
Cell Types ◽  
Polycomb Repressive Complex 2 ◽  
Histone Lysine Methyltransferases

Differentiation and activation of T cells require the activity of numerous histone lysine methyltransferases (HMT) that control the transcriptional T cell output. One of the most potent regulators of T cell differentiation is the HMT Ezh2. Ezh2 is a key enzymatic component of polycomb repressive complex 2 (PRC2), which silences gene expression by histone H3 di/tri-methylation at lysine 27. Surprisingly, in many cell types, including T cells, Ezh2 is localized in both the nucleus and the cytosol. Here we show the presence of a nuclear-like PRC2 complex in T cell cytosol and demonstrate a role of cytosolic PRC2 in T cell antigen receptor (TCR)–mediated signaling. We show that short-term suppression of PRC2 precludes TCR-driven T cell activation in vitro. We also demonstrate that pharmacological inhibition of PRC2 in vivo greatly attenuates the severe T cell–driven autoimmunity caused by regulatory T cell depletion. Our data reveal cytoplasmic PRC2 is one of the most potent regulators of T cell activation and point toward the therapeutic potential of PRC2 inhibitors for the treatment of T cell–driven autoimmune diseases.

scholarly journals PRMT5 Is Required for Bovine Leukemia Virus Infection In Vivo and Regulates BLV Gene Expression, Syncytium Formation, and Glycosylation In Vitro

Viruses ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 650 ◽  
Author(s):  
Wlaa Assi ◽  
Tomoya Hirose ◽  
Satoshi Wada ◽  
Ryosuke Matsuura ◽  
Shin-nosuke Takeshima ◽  
...  
Keyword(s):  
Gene Expression ◽  
Small Molecule ◽  
Bovine Leukemia Virus ◽  
Proviral Load ◽  
Leukemia Virus ◽  
Syncytium Formation ◽  
High Proviral Load

Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis, which is the most common neoplastic disease of cattle and is closely related to human T-cell leukemia viruses. We investigated the role of a new host protein, PRMT5, in BLV infection. We found that PRMT5 is overexpressed only in BLV-infected cattle with a high proviral load, but not in those with a low proviral load. Furthermore, this upregulation continued to the lymphoma stage. PRMT5 expression was upregulated in response to experimental BLV infection; moreover, PRMT5 upregulation began in an early stage of BLV infection rather than after a long period of proviral latency. Second, siRNA-mediated PRMT5 knockdown enhanced BLV gene expression at the transcript and protein levels. Additionally, a selective small-molecule inhibitor of PRMT5 (CMP5) enhanced BLV gene expression. Interestingly, CMP5 treatment, but not siRNA knockdown, altered the gp51 glycosylation pattern and increased the molecular weight of gp51, thereby decreasing BLV-induced syncytium formation. This was supported by the observation that CMP5 treatment enhanced the formation of the complex type of N-glycan more than the high mannose type. In conclusion, PRMT5 overexpression is related to the development of BLV infection with a high proviral load and lymphoma stage and PRMT5 inhibition enhances BLV gene expression. This is the first study to investigate the role of PRMT5 in BLV infection in vivo and in vitro and to reveal a novel function for a small-molecule compound in BLV-gp51 glycosylation processing.

On the role of APC-activation for in vitro versus in vivo T cell priming

2003 ◽  
Vol 225 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Tazio Storni ◽  
Martin F. Bachmann
Keyword(s):  
T Cell ◽  
T Cell Priming

PAK1 Regulates Eotaxin-Mediated Murine Eosinophil Migration in Vitro and In Vivo

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 18-18
Author(s):  
Muithi Mwanthi ◽  
Gracie Michels ◽  
Karl Staser ◽  
Sarita Sehra ◽  
Michal Jander ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
Eosinophil Infiltration ◽  
Chimeric Mouse ◽  
Murine Models ◽  
Eosinophilic Inflammation ◽  
Eosinophil Recruitment ◽  
Eosinophil Migration

Abstract Abstract 18 Eosinophils are increasingly recognized as important myeloid effector cells in the inflammatory environment of many human diseases. Although eosinophils critically contribute to chronic asthmatic inflammation, few therapies directly target these cells. Eosinophils rapidly migrate to eotaxin elicited by allergic sensitization and challenge, a chemokine that ligates the CCR3 receptor. Eotaxin:CCR3 signaling critically regulates allergen-induced eosinophil infiltration in murine models by activating the Rho-family proteins. In several cell systems, the Rho proteins Rac and CDC42 activate p21-activated kinase 1 (PAK1), which we have previously shown to regulate F-actin dynamics and histamine release in the degranulating mast cell. In these studies, we examined eotaxin-induced eosinophil migration using genetic and hematopoietic ablation of Pak1 (Pak1−/−) in a murine asthma model. Using an in vitro transwell migration assay system, we evaluated the migration of bone marrow derived eosinophils of both genotypes to eotaxin (N=10). Pak1−/− eosinophils exhibited profoundly diminished eotaxin-induced chemotaxis in vitro relative to wild-type (Pak1+/+) eosinophils (p < 0.0001) with a 30% overall decrease in migrating Pak1−/− compared to Pak1+/+ eosinophils. Furthermore, we compared the eotaxin-induced localization and arrangement of F-actin in eosinophils of both genotypes by fluorescence cytometry and deconvolution confocal microscopy of fluorescently-tagged phalloidin in seeking to explain this migration defect. Preliminary findings suggest decreased F-actin polymerization in eotaxin-treated Pak1−/− eosinophils. In an independent line of experiments designed to compare eotaxin-mediated eosinophil recruitment in vivo we injected mice of both genotypes with an intraperitoneal dose of eotaxin or saline. Pak1+/+ mice showed an 8 fold eotaxin-mediated increase in eosinophil recruitment over control whereas Pak1−/− mice demonstrated only a modest 3–4 fold increase (p< 0.05). Finally we pursued PAK1's function in an experimental disease model in which the eosinophil's key role in pathogenesis is well documented. In 3 cohorts of 7 age, gender and strain matched Pak1+/+ and Pak1−/− ova albumin (OVA)-sensitized and challenged mice, we scored lung eosinophilic inflammation by histology and compared eosinophil counts and eotaxin concentrations in broncho-alveolar lavage fluid (BALF) by fluorescence cytometry and ELISA respectively. We also assessed OVA-specific T-cell subset cytokine secretion in our asthma mice by ELISA. Lung-parenchymal eosinophilic inflammation was diminished in Pak1−/− ova-sensitized mice versus Pak1+/+'s (p<0.01) with neither differences in BALF eotaxin content nor OVA-specific in vitro T-helper cell secretion of asthma-induced cytokines between the 2 genotypes. Based on our findings in this model, we assessed PAK1's hematopoietic role using two complementary chimeric mouse models. In a cohort of matched recipient Pak1+/+ mice we transplanted Pak1+/+ and Pak1−/− bone marrow and after hematopoietic reconstitution we incited asthmatic inflammation in these mice. Significantly, hosts transplanted with Pak1−/− bone marrow developed decreased eosinophilic inflammation scores compared to Pak1+/+ bone marrow recipients (p<0.05). To complement the bone marrow experiments, we transplanted left-lung grafts from Pak1+/+ and Pak1−/− mice into matched Pak1+/+ and Pak1−/− recipient mice and after surgical recuperation we elicited asthmatic inflammation as above. Similar to our bone marrow transplant experiments, irrespective of the genotype of the lung graft, hosts with Pak1−/− bone marrow developed decreased lung eosinophil infiltrate. Our data suggest that genetic PAK1 disruption hinders the in vitro and in vivo eotaxin-mediated migration of eosinophils by altering polymerization of F-actin. In an OVA murine model of asthma, we show that the genetic ablation of PAK1 attenuates the eosinophilic inflammation without affecting T-cell function. We similarly demonstrate that hematopoietic expression of PAK1 is critical to the development of eosinophil inflammation in two complementary transplant murine models. Pharmacologically targeting PAK1 may thus provide a specific way to impede eosinophil tissue infiltration, alleviate chronic eosinophil inflammation, and hamper long-term tissue remodeling in diseases like asthma. Disclosures: No relevant conflicts of interest to declare.

Effect of a combination of epigenetic agents on the malignant phenotype in models of T-cell lymphoma.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e13569-e13569
Author(s):  
Enrica Marchi ◽  
Matko Kalac ◽  
Danielle Bongero ◽  
Christine McIntosh ◽  
Laura K Fogli ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
Cell Lines ◽  
Molecular Level ◽  
Cell Lymphoma ◽  
Single Agent ◽  
T Cell Lymphoma ◽  
Cytotoxicity Assays

e13569 Background: CHOP and CHOP-like chemotherapy are the most used regimens for the treatment of peripheral T-cell lymphomas (PTCLs) despite sub-optimal results. Histone deacetylase inhibitors (HDACIs) have shown class activity in PTCLs. The interaction between the HDACIs (depsipeptide (R), belinostat (B), vorinostat (V) and panobinostat (P)) and a DNMT inhibitor (decitabine (D) was investigated in vitro, in vivo and at the molecular level in T-cell lymphoma and leukemia cell lines (H9, HH, P12, PF-382). Methods: For cytotoxicity assays, luminescence cell viability assay was used (CellTiter-Glo). Drug:drug interactions were analyzed with relative risk ratios (RRR) based on the GraphPad software (RRR<1 defining synergism). Apoptosis was assessed by Yo-Pro-1 and propidium iodine followed by FACSCalibur acquisition. Gene expression profiling was analyzed using Illumina Human HT-12 v4 Expression BeadChip microarrays and Gene Spring Software for the analysis. Results: The IC50s for B, R, V, P, D and 5-Azacytidine alone were assessed at 24, 48 and 72 hours. In cytotoxicity assays the combination of D plus B, R, V or P at 72 hours showed synergism in all the cell lines (RRRs 0.0007-0.9). All the cell lines were treated with D, B or R for 72 hours and all the combinations showed significantly more apoptosis than the single drug exposures and controls (RRR < 1). In vivo, HH SCID beige mice were treated i.p. for 3 cycles with the vehicle solution, D or B or their combination at increasing dose. The combination cohort showed statistically significant tumor growth inhibition compared to all the other cohorts. Gene expression analysis revealed differentially expressed genes and modulated pathways for each of the single agent treatment and the combination. The effects of the two drugs were largely different (only 39 genes modified in common). Most of the effects induced by the single agent were maintained in the combination group. Interestingly, 944 genes were modulated uniquely by the combination treatment. Conclusions: The combination of a DNMTI and HDACIs is strongly synergistic in vitro, in vivo and at the molecular level in model of T-cell lymphoma and these data will constitute the basis for a phase I-II clinical trials.

Biologic consequences of androgen receptor (AR) activity in MDV3100-resistant LNCaP cells and dependence on AR full length.

2014 ◽  
Vol 32 (4_suppl) ◽  
pp. 74-74
Author(s):  
Yoshiaki Yamamoto ◽  
Yohann Loriot ◽  
Eliana Beraldi ◽  
Tianyuan Zhou ◽  
Youngsoo Kim ◽  
...  
Keyword(s):  
Gene Expression ◽  
Androgen Receptor ◽  
Cell Growth ◽  
Functional Role ◽  
Full Length ◽  
Lncap Cells ◽  
Exon 1

74 Background: While recent reports link androgen receptor (AR) variants (AR-Vs) to castration resistant prostate cancer (CRPC), the biological significance of AR-Vs in AR-regulated cell survival and proliferation, independent of AR full length (AR-FL), remains controversial. To define the functional role of AR-FL and AR-Vs in MDV3100-resistant (MDV-R), we designed antisense oligonucleotide (ASO) targeting exon 1 and exon 8 in AR to knockdown AR-FL alone or in combination with AR-Vs and examined these effects in MDV-R LNCaP-derived cells in vitro and in vivo. Methods: We generated by selection MDV-R LNCaP-derived sub-lines that uniformly expressed high levels of both AR-FL and AR-V7 compared to CRPC LNCaP xenografts. Cell growth rates, protein and gene expression were analyzed using crystal violet assay, western blotting and real-time PCR, respectively. Exon 1 and 8 AR-ASO were evaluated in MDV-R49F CRPC LNCaP xenografts. Results: AR-V7 was transiently transfected in MDV-R49F cells and differential knockdown of AR-V7 and/or AR-FL by exon 1 versus exon 8 AR-ASO was used to evaluate relative biologic contributions of AR-FL versus AR-V7 in MDV-R LNCaP AR-V7 overexpressing cells. Exon 1 and 8 AR-ASO treatment in these cells similarly decreased prostate-specific antigen (PSA) expression and induced apoptosis as measured by caspase-3 and PARP cleavage and cell growth inhibition. To further define the functional role of AR-Vs in MDV-R LNCaP cells, we used a CE3 siRNA that specifically silenced AR-V7, but not AR-FL in MDV-R LNCaP cells. AR-V7 knockdown did not decrease PSA levels, did not induce apoptosis, and did not inhibit cell growth. In MDV-R LNCaP cells, exon 1 and 8 ASO similarly suppressed cell growth and AR-regulated gene expression in vitro and in vivo. Conclusions: These results indicate that the AR remains an important driver of MDV3100 resistance and, the biologic consequences mainly driven by AR-FL in MDV-R LNCaP models.

scholarly journals Studying the immunosuppressive role of indoleamine 2,3-dioxygenase: tryptophan metabolites suppress rat allogeneic T-cell responses in vitro and in vivo

2005 ◽  
Vol 18 (1) ◽  
pp. 95-100 ◽  
Author(s):  
Thomas M. Bauer ◽  
Lucian P. Jiga ◽  
Jing-Jing Chuang ◽  
Marco Randazzo ◽  
Gerhard Opelz ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Responses ◽  
Cell Responses ◽  
Indoleamine 2,3 Dioxygenase ◽  
Tryptophan Metabolites

scholarly journals IL-27 promotes T cell–dependent colitis through multiple mechanisms

2010 ◽  
Vol 208 (1) ◽  
pp. 115-123 ◽  
Author(s):  
Jennifer H. Cox ◽  
Noelyn M. Kljavin ◽  
Nandhini Ramamoorthi ◽  
Lauri Diehl ◽  
Marcel Batten ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Intestinal Inflammation ◽  
Interferon Γ ◽  
Transfer Model ◽  
Proinflammatory Role ◽  
Immune Pathology

Interleukin-27 (IL-27) is a cytokine known to have both proinflammatory and immunoregulatory functions. The latter appear to dominate in vivo, where IL-27 suppresses TH17 responses and promotes the differentiation of Tr1 cells expressing interferon-γ and IL-10 and lacking forkhead box P3 (Foxp3). Accordingly, IL-27 receptor α (Il27ra)–deficient mice suffer from exacerbated immune pathology when infected with various parasites or challenged with autoantigens. Because the role of IL-27 in human and experimental mouse colitis is controversial, we studied the consequences of Il27ra deletion in the mouse T cell transfer model of colitis and unexpectedly discovered a proinflammatory role of IL-27. Absence of Il27ra on transferred T cells resulted in diminished weight loss and reduced colonic inflammation. A greater fraction of transferred T cells assumed a Foxp3+ phenotype in the absence of Il27ra, suggesting that IL-27 functions to restrain regulatory T cell (Treg) development. Indeed, IL-27 suppressed Foxp3 induction in vitro and in an ovalbumin-dependent tolerization model in vivo. Furthermore, effector cell proliferation and IFN-γ production were reduced in the absence of Il27ra. Collectively, we describe a proinflammatory role of IL-27 in T cell–dependent intestinal inflammation and provide a rationale for targeting this cytokine in pathological situations that result from a breakdown in peripheral immune tolerance.

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