Project description:Leukemic blasts are immune cells gone awry. We hypothesized that dysregulation of inflammatory pathways contributes to the maintenance of their leukemic state and can be exploited as a cell-intrinsic, self-directed immunotherapy. To this end, we applied genome-wide screens to discover genetic vulnerabilities in acute myeloid leukemia (AML) cells that are also implicated in inflammatory pathways. We identified the immune modulator interferon regulatory factor 2 binding protein 2 (IRF2BP2) as a selective dependency in AML. We validated AML cell dependency on IRF2BP2 with genetic and protein degradation approaches in vitro and genetically in vivo. Chromatin and global gene expression studies demonstrated that IRF2BP2 represses IL1B/TNFA signaling via NF-KB, and IRF2BP2 perturbation results in an acute inflammatory state leading to AML cell death. These findings elucidate a hitherto unexplored AML dependency, reveal cell-intrinsic inflammatory signaling as a mechanism priming leukemic blasts for regulated cell death, and establish IRF2BP2-mediated transcriptional repression as a mechanism for blast survival.
Project description:Leukemic blasts are immune cells gone awry. We hypothesized that dysregulation of inflammatory pathways contributes to the maintenance of their leukemic state and can be exploited as a cell-intrinsic, self-directed immunotherapy. To this end, we applied genome-wide screens to discover genetic vulnerabilities in acute myeloid leukemia (AML) cells that are also implicated in inflammatory pathways. We identified the immune modulator interferon regulatory factor 2 binding protein 2 (IRF2BP2) as a selective dependency in AML. We validated AML cell dependency on IRF2BP2 with genetic and protein degradation approaches in vitro and genetically in vivo. Chromatin and global gene expression studies demonstrated that IRF2BP2 represses IL1B/TNFA signaling via NF-KB, and IRF2BP2 perturbation results in an acute inflammatory state leading to AML cell death. These findings elucidate a hitherto unexplored AML dependency, reveal cell-intrinsic inflammatory signaling as a mechanism priming leukemic blasts for regulated cell death, and establish IRF2BP2-mediated transcriptional repression as a mechanism for blast survival.
Project description:In the present study, we investigated whether, and to what extent, P2Rs and their ligands are involved in the regulation of AML cells. Our findings show that AML blasts express several receptors belonging to the P2X and P2Y family. Although different samples respond differently to ATP and UTP stimulation (reflecting the variability intrinsic to the group of acute myeloid leukemias), all the tested samples appear to be responsive to purinergic signalling, as demonstrated by intracellular calcium mobilization. GEP analysis demonstrated that ATP induced the expression of cell cycle inhibitors and negative modulators of cell motility, such as inhibitors of GTPase activity. On the contrary, ATP inhibits the expression cell-cycle related genes (cyclins and CDKs), activators of cell motility (Rho GTPases regulators, matrix degradation enzyme and cytoskeleton proteins) and adhesion molecules involved in homing and engraftment. Blast cells obtained from 12 AML patients (3 M0/M1; 3 M2; 3 M4; and 3 M5) were cultured for 24 h with or without 1 mM ATP. Total RNA from 106 ATP-treated and untreated cells was extracted to study variation of gene expression profile induced by ATP treatment in leukemic cells.
Project description:In the present study, we investigated whether, and to what extent, P2Rs and their ligands are involved in the regulation of AML cells. Our findings show that AML blasts express several receptors belonging to the P2X and P2Y family. Although different samples respond differently to ATP and UTP stimulation (reflecting the variability intrinsic to the group of acute myeloid leukemias), all the tested samples appear to be responsive to purinergic signalling, as demonstrated by intracellular calcium mobilization. GEP analysis demonstrated that ATP induced the expression of cell cycle inhibitors and negative modulators of cell motility, such as inhibitors of GTPase activity. On the contrary, ATP inhibits the expression cell-cycle related genes (cyclins and CDKs), activators of cell motility (Rho GTPases regulators, matrix degradation enzyme and cytoskeleton proteins) and adhesion molecules involved in homing and engraftment.
Project description:Treatment for acute myeloid leukemia (AML) remains suboptimal and many patients remain refractory or relapse upon standard chemotherapy based on nucleoside analogs plus anthracyclines. The crosstalk between AML cells and the bone marrow (BM) stroma is a major mechanism underlying therapy resistance in AML. Lenalidomide and pomalidomide, a new generation immunomodulatory drugs (IMiDs), possess pleiotropic anti-leukemic properties including potent immune-modulating effects and are commonly used in hematological malignances associated with intrinsic dysfunctional BM such as myelodysplastic syndromes and multiple myeloma. Whether IMiDs may improve the efficacy of current standard treatment in AML remains understudied. Here, we have exploited in vitro and in vivo preclinical AML models to analyze whether IMiDs potentiate the efficacy of AraC/Iradubicin (standard AML chemotherapy) by interfering with the BM stroma-mediated chemoresistance. We report that lenalidomide and pomalidomide have cytotoxic effects on neither AML cells nor BM-MSCs, but they increase the immunosuppressive/immunomodulatory properties of BM-MSCs. When combined with AraC and Idarubicin, IMiDs fail to circumvent BM stroma-mediated resistance of AML cells in vitro and in vivo but induce robust extramedullary mobilization of AML cells. When administered as a single agent, lenalidomide highly mobilizes AML cells, but not healthy CD34+ cells, to peripheral blood (PB) likely through specific downregulation of CXCR4 in AML blasts. Global gene expression profiling supports a migratory/mobilization gene signature in lenalidomide-treated AML blasts but not in CD34+ cells. Collectively, IMiDs mobilize AML blasts to PB through downregulation of CXCR4 but do not improve AraC/Idarubicin activity in a preclinical model of AML.
Project description:While type I interferon (IFN) is best known for its key role against viral infection, accumulating preclinical and clinical data indicate that robust type I IFN production in the tumor microenvironment promotes cancer immunosurveillance and contributes to the efficacy of various antineoplastic agents, notably immunogenic cell death inducers. Here, we report that malignant blasts from patients with acute myeloid leukemia (AML) release type I IFN via a Toll-like receptor (TLR3)-dependent mechanism that is not influenced by treatment. While in these patients the ability of type I IFN to stimulate anticancer immune responses was abolished by immunosuppressive mechanisms driven by malignant blasts, type I IFN turned out to exert direct cytostatic, cytotoxic and chemosensitizing activity in primary AML blasts, leukemic stem cells from AML patients and AML xenograft models. Finally, a genetic signature of type I IFN signaling has independent prognostic value on relapse-free survival and overall survival in cohort of 132 AML patients. These findings delineate a clinically relevant, therapeutically actionable and prognostically informative mechanism through which type I IFN mediates beneficial effects in patients with AML.
Project description:CD133-positive immature blasts were purified from bone marrow of the patients. Total RNA was extracted by RNeasy mini spin column (Qiagen, Inc). SUBMITTER_CITATION: Yamashita Y, Ohashi J, Hirai Y, Choi YL, Kaneda R, Fujiwara S-i, Arai Y, Akutsu M, Tsutsumi C, Miyazaki Y, Usuki K, Teramura M, Mitani K, Kano Y, O'Neill MC, Urabe A, Tomonaga M, Ozawa K & Mano H. Gene expression profiles of CD133-positive fractions predict the survival of individuals with acute myeloid leukemia 2006, Cancer Genomics & Proteomics, 3:169-182.