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MicroRNA-146a modulates B-cell oncogenesis by regulating EGR1

ABSTRACT: miR-146a is a NF-κB induced microRNA that serves as a feedback regulator of this critical pathway. In mice, deficiency of miR-146a results in hematolymphoid cancer at advanced ages as a consequence of constitutive NF-κB activity. In this study, we queried whether the deficiency of miR-146a contributes to B-cell oncogenesis. Combining miR-146a deficiency with transgenic expression of c-Myc led to the development of highly aggressive B-cell malignancies. Mice transgenic for c-Myc and deficient for miR-146a were characterized by significantly shortened survival, increased lymph node involvement, differential involvement of the spleen and a mature B-cell phenotype. High-throughput sequencing of the tumors revealed significant dysregulation of approximately 250 genes. Amongst these, the transcription factor Egr1 was consistently upregulated in mice deficient for miR-146a. Interestingly, transcriptional targets of Egr1 were enriched in both the high-throughput dataset and in a larger set of miR-146a-deficient tumors. miR-146a overexpression led to downregulation of Egr1 and downstream targets with concomitant decrease in cell growth. Direct targeting of the human EGR1 by miR-146a was seen by luciferase assay. Together our findings illuminate a bona fide role for miR-146a in the modulation of B-cell oncogenesis and reveal the importance of understanding microRNA function in a cell- and disease-specific context.

ORGANISM(S): Mus musculus

PROVIDER: GSE67113 | GEO | 2016/03/20

SECONDARY ACCESSION(S): PRJNA278976

REPOSITORIES: GEO

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Project description:NF-κB is a key regulator of inflammation and cancer progression, with important role in leukemogenesis. Despite therapeutic potential, targeting NF-κB using pharmacologic inhibitors proved challenging. Here, we describe a myeloid cell-selective NF-κB inhibitor using miR146a mimic oligonucleotide conjugated to a scavenger receptor (SR)/Toll-like receptor 9 (TLR9) agonist (C-miR146a). Unlike an unconjugated miR-146a, C-miR146a was rapidly internalized and delivered to cytoplasm of target myeloid cells and leukemic cells. C-miR146a reduced expression of classic miR-146a targets, IRAK1 and TRAF6, thereby blocking NF-κB activation in target cells. Intravenous injections of C-miR146a mimic to miR-146-deficient mice prevented excessive NF-κB activation in myeloid cells, thereby alleviating myeloproliferation and mice hypersensitivity to bacterial challenge. Importantly, C-miR146a showed efficacy in dampening severe inflammation in clinically relevant models of chimeric antigen receptor (CAR) T-cell-induced cytokine release syndrome (CRS). Systemic administration of C-miR146a oligonucleotide alleviated human monocyte-dependent release of IL-1 and IL-6 in xenotransplanted B-cell lymphoma model without affecting CD19-specific CAR T-cell antitumor activity. Beyond anti-inflammatory functions, miR146a is a known tumor suppressor commonly deleted or expressed at reduced levels in human myeloid leukemia. Using TCGA AML dataset, we found inverse correlation of miR-146 levels with NF-κB-related genes and with patients’ survival. Correspondingly, C-miR146a induced cytotoxic effects in human MDSL, HL-60 and MV4-11 leukemia cells in vitro. The repeated intravenous administration of C-miR146a inhibited expression of NF-κB target genes and thereby thwarted progression of disseminated HL-60 leukemia. Our results demonstrate potential of using myeloid cell-targeted miR146a mimics for treatment of inflammatory and myeloproliferative disorders. NF-κB is a key regulator of inflammation and cancer progression, with important role in leukemogenesis. Despite therapeutic potential, targeting NF-κB using pharmacologic inhibitors proved challenging. Here, we describe a myeloid cell-selective NF-κB inhibitor using miR146a mimic oligonucleotide conjugated to a scavenger receptor (SR)/Toll-like receptor 9 (TLR9) agonist (C-miR146a). Unlike an unconjugated miR-146a, C-miR146a was rapidly internalized and delivered to cytoplasm of target myeloid cells and leukemic cells. C-miR146a reduced expression of classic miR-146a targets, IRAK1 and TRAF6, thereby blocking NF-κB activation in target cells. Intravenous injections of C-miR146a mimic to miR-146-deficient mice prevented excessive NF-κB activation in myeloid cells, thereby alleviating myeloproliferation and mice hypersensitivity to bacterial challenge. Importantly, C-miR146a showed efficacy in dampening severe inflammation in clinically relevant models of chimeric antigen receptor (CAR) T-cell-induced cytokine release syndrome (CRS). Systemic administration of C-miR146a oligonucleotide alleviated human monocyte-dependent release of IL-1 and IL-6 in xenotransplanted B-cell lymphoma model without affecting CD19-specific CAR T-cell antitumor activity. Beyond anti-inflammatory functions, miR146a is a known tumor suppressor commonly deleted or expressed at reduced levels in human myeloid leukemia. Using TCGA AML dataset, we found inverse correlation of miR-146 levels with NF-κB-related genes and with patients’ survival. Correspondingly, C-miR146a induced cytotoxic effects in human MDSL, HL-60 and MV4-11 leukemia cells in vitro. The repeated intravenous administration of C-miR146a inhibited expression of NF-κB target genes and thereby thwarted progression of disseminated HL-60 leukemia. Our results demonstrate potential of using myeloid cell-targeted miR146a mimics for treatment of inflammatory and myeloproliferative disorders.

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MicroRNA-146a modulates B-cell oncogenesis by regulating EGR1

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