Project description:microRNA are aberrantly expressed in acute myeloid leukemia (AML), and clinically may have diagnostic, prognostic, and therapeutic value. We identify one such microRNA, miR-196b, is essential for MLL-AF9 leukemia initiation and maintenance. To discover how miR-196b contributes to leukemogenesis, we utilized multiple unbiased approaches that identified and functionally screened miR-196b target activity in AML. Our studies resolved how conflicting networks of miRNA-regulated targets are integrated during leukemogenesis. This work uncovered two miR-196b direct targets, the cell cycle regulator Cdkn1b (p27Kip1) and Polycomb group member Phc2, that independently cooperate with MLL-AF9 to promote leukemogenesis by regulating stem cell transcriptional programs. Finally, we found that therapeutic disruption of miR-196b direct targeting of Cdkn1b suppresses leukemogenesis.
Project description:microRNA are aberrantly expressed in acute myeloid leukemia (AML), and clinically may have diagnostic, prognostic, and therapeutic value. We identify one such microRNA, miR-196b, is essential for MLL-AF9 leukemia initiation and maintenance. To discover how miR-196b contributes to leukemogenesis, we utilized multiple unbiased approaches that identified and functionally screened miR-196b target activity in AML. Our studies resolved how conflicting networks of miRNA-regulated targets are integrated during leukemogenesis. This work uncovered two miR-196b direct targets, the cell cycle regulator Cdkn1b (p27Kip1) and Polycomb group member Phc2, that independently cooperate with MLL-AF9 to promote leukemogenesis by regulating stem cell transcriptional programs. Finally, we found that therapeutic disruption of miR-196b direct targeting of Cdkn1b suppresses leukemogenesis.
Project description:This study report that miR-150, a key hematopoietic regulatory microRNA (miRNA) and one of the most downregulated miRNAs in MLL-associated leukemias, acts as a tumor suppressor to block the leukemogenic potency of leukemic stem cells. When expression of miR-150 was restored, a significantly suppressed leukemic stem cell potency of MLL-AF9 cells was observed both in vivo and in vitro. To investigate the tumor suppressive function of miR-150 in MLL-AF9 cells, we isolated three batches of MLL-AF9 cells infected with MDH empty vector or MDH-miR-150 expression retrovirus. Total RNA were extracted and applied for Agilent array analysis. Gene profiling analysis demonstrated that elevated miR-150 altered various aspects of gene expression patterns in MLL-AF9 cells, including stem cell signatures, cancer pathways, and cell survival. miR-150-MLL-AF9 and MDH-MLL-AF9 isolated cells were compared for gene expression patterns. Triplicates using three batches of FACS sorted cells were compared in pairs on the array. MDH-MLL-AF9 samples were labeld with Cy3 and miR-150-MLL-AF9 samples were labled with Cy5.
Project description:This study report that miR-150, a key hematopoietic regulatory microRNA (miRNA) and one of the most downregulated miRNAs in MLL-associated leukemias, acts as a tumor suppressor to block the leukemogenic potency of leukemic stem cells. When expression of miR-150 was restored, a significantly suppressed leukemic stem cell potency of MLL-AF9 cells was observed both in vivo and in vitro. To investigate the tumor suppressive function of miR-150 in MLL-AF9 cells, we isolated three batches of MLL-AF9 cells infected with MDH empty vector or MDH-miR-150 expression retrovirus. Total RNA were extracted and applied for Agilent array analysis. Gene profiling analysis demonstrated that elevated miR-150 altered various aspects of gene expression patterns in MLL-AF9 cells, including stem cell signatures, cancer pathways, and cell survival.
Project description:HOXA9 and MEIS1 are essential downstream effectors of the MLL-AF9 oncoprotein during leukemia induction. Leukemia derived from MLL-AF9-transduced LSK cells has a more aggressive phenotype than that derived from HOXA9/MEIS1-transduced LSK cells. To determine differential miRNA expression that contributes to increased aggressiveness in MLL-AF9-induced leukemia, miRCURY LNA microRNA Array was performed on LSK cells transduced with MLL-AF9 versus HOXA/MEIS1 oncogenes.
Project description:To identify such targets of leukemia-related miRNAs such as miR-196b, we conducted Affymetrix gene arrays of leukemic BM samples from 24 mice including 9 primary (including 3 each of negative control, MLL-AF9, and miR-196b+MLL-AF9) and 15 secondary (including 3 negative control, 6 MLL-AF9, and 6 miR-196b+MLL-AF9) recipient mice
Project description:To identify such targets of leukemia-related miRNAs such as miR-196b, we conducted Affymetrix gene arrays of leukemic BM samples from 24 mice including 9 primary (including 3 each of negative control, MLL-AF9, and miR-196b+MLL-AF9) and 15 secondary (including 3 negative control, 6 MLL-AF9, and 6 miR-196b+MLL-AF9) recipient mice A total of 24 mouse bone marrow samples including 9 primary (including 3 each of negative control, MLL-AF9, and miR-196b+MLL-AF9) and 15 secondary (including 3 negative control, 6 MLL-AF9, and 6 miR-196b+MLL-AF9) obtained from the in vivo mouse bone marrow reconstitution assays were analyzed by use of Affymetrix GeneChip Mouse Gene 1.0 ST Array (Affymetirx, Santa Clara, CA)
Project description:The pathways by which oncogenes, such as MLL-AF9, initiate transformation and leukemia in humans and mice are incompletely defined. In a study of target cells and oncogene dosage, we found that Mll-AF9, when under endogenous regulatory control, efficiently transformed LSK (Lin- Sca1+ c-kit+) stem cells while committed granulocyte-monocyte progenitors (GMPs) were transformation-resistant and did not cause leukemia. Mll-AF9 was expressed at higher levels in hematopoietic stem (HSC) than GMP cells. Mll- AF9 gene dosage effects were directly shown in experiments where GMPs were efficiently transformed by the high dosage of Mll-AF9 resulting from retroviral transduction. Mll-AF9 up-regulated expression of 196 genes in both LSK and progenitor cells, but to higher levels in LSKs than in committed myeloid progenitors. Keywords: mutant hematopoietic cells
Project description:The pathways by which oncogenes, such as MLL-AF9, initiate transformation and leukemia in humans and mice are incompletely defined. In a study of target cells and oncogene dosage, we found that Mll-AF9, when under endogenous regulatory control, efficiently transformed LSK (Lin- Sca1+ c-kit+) stem cells while committed granulocyte-monocyte progenitors (GMPs) were transformation-resistant and did not cause leukemia. Mll-AF9 was expressed at higher levels in hematopoietic stem (HSC) than GMP cells. Mll- AF9 gene dosage effects were directly shown in experiments where GMPs were efficiently transformed by the high dosage of Mll-AF9 resulting from retroviral transduction. Mll-AF9 up-regulated expression of 196 genes in both LSK and progenitor cells, but to higher levels in LSKs than in committed myeloid progenitors. Experiment Overall Design: Comparison of gene expression profiles among four types of hematopoietic cells (GMP, CMP, CLP and HSC), FACS sorted from wild type and Mll-AF9 knock-in mice. The goal was to identify genes differentially expressed in each Mll-AF9 cell type compared to the corresponding wild type cells.
Project description:The translocation t(9;11)(p22;q23) leading to the leukemogenic fusion gene MLL-AF9 is a frequent translocation in infant acute myeloid leukemia (AML). This study aimed to identify genes and molecular processes downstream of MLL-AF9 (alias MLL-MLLT3) which could assist to develop new targeted therapies for such leukemia with unfavorable prognosis. In the AML cell line THP1 which harbors this t(9;11) translocation, endogenous MLL-AF9 was silenced via siRNA while ensuring specificity of the knockdown and its efficiency on functional protein level. The differential gene expression profile was validated for leukemia-association by gene set enrichment analysis of published gene sets from patient studies and MLL-AF9 overexpression studies and revealed 425 differentially expressed genes. Gene ontology analysis was consistent with a more differentiated state of MLL-AF9 depleted cells, with involvement of a wide range of downstream transcriptional regulators and with defined functional processes such as ribosomal biogenesis, chaperone binding, calcium homeostasis and estrogen response. Besides potential new therapeutic targets, the described transcription profile shaped by MLL-AF9 provides an information source into the molecular processes altered in MLL aberrant leukemia. 4 samples were analyzed, each corresponding to a pool of five independent replicate experiments. MLL-AF9 knockdown treatments are represented by 2 pooled samples employing two distinct siRNAs, each targeting MLL-AF9 breakpoint of THP1 cells. Control treatments are represented by 2 pooled samples employing two distinct non-targeting control siRNAs. siRNA-3 = siRNA-A in publication siRNA-4 = siRNA-B in publication