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Hypoxia-sensitive epigenetic regulation of an antisense-oriented lncRNA controls WT1 expression in myeloid leukemia cells.

ABSTRACT: WT1 is a transcription factor expressed in hematopoietic stem cells and in most cases of myeloid leukemia. We investigated the roles of hypoxia and epigenetics in the regulation of WT1 expression in myeloid leukemia cells. WT1 expression correlates with hypomethylation of the CpG island in Intron 1, and pharmacologic demethylation of this CpG island induces WT1 mRNA expression. Hypoxia causes decreases in DNMT expression and activity and increased expression and activity of TET2 and TET3, resulting in demethylation of this CpG island and expression of WT1 mRNA. Demethylation of the CpG island, either from pharmacologic treatment or induction of hypoxia, results in transcription of an antisense-oriented lncRNA, and inhibiting lncRNA expression with shRNA blocks WT1 mRNA expression. These results reveal a novel model of hypoxia-mediated epigenetic gene regulation. In addition, this is the first report that TET2 and TET3, increasingly recognized as important epigenetic regulators of gene expression in stem cells and in cancer cells, can be regulated by hypoxia, providing a solid mechanistic link between hypoxia and epigenetic regulation of gene expression with important implications for the role of hypoxia in stem cell function.

SUBMITTER: McCarty G

PROVIDER: S-EPMC4368825 | biostudies-other | 2015

REPOSITORIES: biostudies-other

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Hypoxia-sensitive epigenetic regulation of an antisense-oriented lncRNA controls WT1 expression in myeloid leukemia cells.

McCarty Gregory G Loeb David M DM

PloS one 20150320 3

WT1 is a transcription factor expressed in hematopoietic stem cells and in most cases of myeloid leukemia. We investigated the roles of hypoxia and epigenetics in the regulation of WT1 expression in myeloid leukemia cells. WT1 expression correlates with hypomethylation of the CpG island in Intron 1, and pharmacologic demethylation of this CpG island induces WT1 mRNA expression. Hypoxia causes decreases in DNMT expression and activity and increased expression and activity of TET2 and TET3, result ...[more]

PMID: 25794157

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Project description:The gene encoding the tumor suppressor p53 is the most frequently mutated gene in cancers. However, p53 mutation is rare in acute myeloid leukemia (AML), and p53 is inactivated predominantly by aberrant expression of p53 regulators (such as MDM2). A previous study by the authors revealed that the ZCCHC10 protein suppressed MDM2‑mediated degradation of the p53 protein in lung cancer. However, the expression and role of the ZCCHC10 gene in AML have not been investigated. In the present study, it was found that ZCCHC10 expression was downregulated in bone marrow samples of AML patients and that ZCCHC10 expression was significantly and negatively correlated with the expression of the lncRNA SNHG1. Suppression of SNHG1 decreased ZCCHC10 promoter methylation and increased ZCCHC10 expression. Notably, there is a putative binding motif in SNHG1 with full complementarity to five sites surrounding the CpG island in the ZCCHC10 promoter. Overexpression of wild‑type SNHG1 promoted ZCCHC10 methylation, but overexpression of SNHG1 with deletion of the binding motif did not. Further study identified that SNHG1 simultaneously bound to the ZCCHC10 promoter and the DNA methyltransferases DNMT1 and DNMT3B. These results indicated that SNHG1 recruits DNMT1 and DNMT3B to the ZCCHC10 promoter, resulting in hypermethylation of the ZCCHC10 promoter. Kaplan‑Meier survival analysis showed that ZCCHC10 expression was positively associated with overall survival in AML patients. In vitro experiments demonstrated that ZCCHC10 increased p53 expression and suppressed AML cell proliferation and survival. In the xenograft mouse model, ZCCHC10 decreased the proliferation of leukemic cells, improved the survival of leukemic mice, and increased sensitivity to the BCL inhibitor venetoclax. In conclusion, ZCCHC10 expression is suppressed by SNHG1‑induced DNA methylation in AML. Downregulation of ZCCHC10 decreases p53 activation, promotes cell proliferation and survival, and thereby accelerates AML progression and the acquisition of venetoclax resistance. The present study identified a SNHG1/ZCCHC10/p53 signaling axis in AML that may be a therapeutic target in this malignancy.

Project description:Wilms' tumor 1 antigen (WT1) is overexpressed in acute myeloid leukemia (AML), a high-risk neoplasm warranting development of novel immunotherapeutic approaches. Unfortunately, clinical immunotherapeutic use of WT1 peptides against AML has been inconclusive. With the rationale of stimulating multiantigenic responses against WT1, we genetically programmed long-lasting dendritic cells capable of producing and processing endogenous WT1 epitopes. A tricistronic lentiviral vector co-expressing a truncated form of WT1 (lacking the DNA-binding domain), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-4 (IL-4) was used to transduce human monocytes ex vivo. Overnight transduction induced self-differentiation of monocytes into immunophenotypically stable "SmartDC/tWT1" (GM-CSF(+), IL-4(+), tWT1(+), IL-6(+), IL-8(+), TNF-α(+), MCP-1(+), HLA-DR(+), CD86(+), CCR2(+), CCR5(+)) that were viable for 3 weeks in vitro. SmartDC/tWT1 were produced with peripheral blood mononuclear cells (PBMC) obtained from an FLT3-ITD(+) AML patient and surplus material from a donor lymphocyte infusion (DLI) and used to expand CD8(+) T cells in vitro. Expanded cytotoxic T lymphocytes (CTLs) showed antigen-specific reactivity against WT1 and against WT1(+) leukemia cells. SmartDC/tWT1 injected s.c. into Nod.Rag1(-/-).IL2rγc(-/-) mice were viable in vivo for more than three weeks. Migration of human T cells (huCTLs) to the immunization site was demonstrated following adoptive transfer of huCTLs into mice immunized with SmartDC/tWT1. Furthermore, SmartDC/tWT1 immunization plus adoptive transfer of T cells reactive against WT1 into mice resulted in growth arrest of a WT1(+) tumor. Gene array analyses of SmartDC/tWT1 demonstrated upregulation of several genes related to innate immunity. Thus, SmartDC/tWT1 can be produced in a single day of ex vivo gene transfer, are highly viable in vivo, and have great potential for use as immunotherapy against malignant transformation overexpressing WT1.

Project description:BackgroundOverexpression of Wilms' tumor-1 (WT1) transcription factor facilitates proliferation in acute myeloid leukemia (AML). However, whether WT1 is enriched in the leukemia-initiating cells (LICs) and leukemia stem cells (LSCs) and facilitates the self-renewal of LSCs remains poorly understood.MethodsMLL-AF9-induced murine leukemia model was used to evaluate the effect of knockdown of wt1 on the self-renewal ability of LSC. RNA sequencing was performed on WT1-overexpressing cells to select WT1 targets. Apoptosis and colony formation assays were used to assess the anti-leukemic potential of a deubiquitinase inhibitor WP1130. Furthermore, NOD/SCID-IL2R? (NSG) AML xenotransplantation and MLL-AF9-induced murine leukemia models were used to evaluate the anti-leukemogenic potential of WP1130 in vivo.ResultsWe found that wt1 is highly expressed in LICs and LSCs and facilitates the maintenance of leukemia in a murine MLL-AF9-induced model of AML. WT1 enhanced the self-renewal of LSC by increasing the expression of BCL2L2, a member of B cell lymphoma 2 (BCL2) family, by direct binding to its promoter region. Loss of WT1 impaired self-renewal ability in LSC and delayed the progression of leukemia. WP1130 was found to modify the WT1-BCL2L2 axis, and WP1130-induced anti-leukemic activity was mediated by ubiquitin proteasome-mediated destruction of WT1 protein. WP1130 induced apoptosis and decreased colony formation abilities of leukemia cells and prolonged the overall survival in the THP1-based xenograft NSG mouse model. WP1130 also decreased the frequency of LSC and prolonged the overall survival in MLL-AF9-induced murine leukemia model. Mechanistically, WP1130 induced the degradation of WT1 by positively affecting the ubiquitination of WT1 protein.ConclusionsOur results indicate that WT1 is required for the development of AML. WP1130 exhibits anti-leukemic activity by inhibiting the WT1-BCL2L2 axis, which may represent a new acute myeloid leukemia therapy target.

Dataset Information

Hypoxia-sensitive epigenetic regulation of an antisense-oriented lncRNA controls WT1 expression in myeloid leukemia cells.

Publications

Hypoxia-sensitive epigenetic regulation of an antisense-oriented lncRNA controls WT1 expression in myeloid leukemia cells.

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