MLL partner genes confer distinct biological and clinical signatures of pediatric AML, an AIEOP study
ABSTRACT: We retrospectively analyzed AML patients enrolled in the AIEOP since 2000, 42 patients with 11q23 rearrangement were analyzed by gene expression profile Gene expression analyses were performed to compare AML MLL partner genes (AF9, AF10, AF6, ENL, ELL, Septin 6, and AF1q) Keywords: Expression data Overall design: Class comparison between different AML MLL partner genes
INSTRUMENT(S): [HG-U133_Plus_2] Affymetrix Human Genome U133 Plus 2.0 Array
Project description:We retrospectively analyzed AML patients enrolled in the AIEOP since 2000, 42 patients with 11q23 rearrangement were analyzed by gene expression profile Gene expression analyses were performed to compare AML MLL partner genes (AF9, AF10, AF6, ENL, ELL, Septin 6, and AF1q) Keywords: Expression data Class comparison between different AML MLL partner genes
Project description:ZNF521 is a multiple zinc finger transcription factor previously identified because abundantly and selectively expressed in normal CD34+ hematopoietic stem and progenitor cells. From microarray datasets, aberrant expression of ZNF521 has been reported in both pediatric and adult acute myeloid leukemia (AML) patients with MLL gene rearrangements. However, a proper validation of microarray data is lacking, likewise ZNF521 contribution in MLL-rearranged AML is still uncertain. In this study, we show that ZNF521 is significantly upregulated in MLL translocated AML patients from a large pediatric cohort, regardless of the type of MLL translocations such as MLL-AF9, MLL-ENL, MLL-AF10 and MLL-AF6 fusion genes. Our in vitro functional studies demonstrate that ZNF521 play a critical role in the maintenance of the undifferentiated state of MLL-rearranged cells. Furthermore, analysis of the ZNF521 gene promoter region shows that ZNF521 is a direct downstream target of both MLL-AF9 and MLL-ENL fusion proteins. Gene expression profiling of MLL-AF9-rearranged THP-1 cells after depletion of ZNF521 reveals correlation with several expression signatures including stem cell-like and MLL fusion dependent programs. These data suggest that MLL fusion proteins activate ZNF521 expression to maintain the undifferentiated state and contribute to leukemogenesis. ZNF521 is required to block differentiation in MLL-rearranged AML cells Overall design: Gene expression was measured on Affymetrix in 3 independent experiments of THP-1 cells transfected with Lentiviral shRNA vector against ZNF521 (shZNF521) or control scrambled shRNA (shScram)
Project description:RNA-Seq of 1) human AML samples; 2) sorted, uncultured distinct population from human cord blood (CB); 3) short-term (ST) cultured sorted CB cells transduced with MLL-ENL, MLL-AF6 or untransduced; and 4) cultured (LT) sorted CB cells transformed with MLL-ENL or MLL-AF6. Cells from MLL-fusion AML patients are bulk. Several cords were used for the sorting (CB1, CB2, CB3, 135, 141...) and these represent biological replicates. Several samples were sequenced several times in different lanes and results were merged together for the analysis (rep1,rep2...). Samples were used to determine the different effect of MLL-fusions in different celltypes just after the transduction, and after a longer time period when cells were transformed. Sorted CB samples, uncultured as well as transformed by MLL-fusions, were used in machine learning approach to predict which of the patients originated from which cell-type of origin.
Project description:Chromosomal rearrangements of the Mixed Lineage Leukemia (MLL) gene result in fusion proteins which retain the N-terminal portion of MLL fused with one of more than 70 different fusion partners. The high diversity of MLL fusion partners raises a question whether it is possible to develop a general therapeutic strategy to block the oncogenic activity of MLL fusion proteins in a fusion partner independent manner. We have demonstrated that blocking the menin-MLL interaction using small molecule inhibitor inhibits oncogenic activity of different MLL fusion proteins according to a mechanism that is independent on the fusion partner. Overall design: MLL-AF9, MLL-AF6 and MLL-AF1P transformed cells were treated with the menin-MLL inhibitor MI-2-2
Project description:Acute Myeloid Leukemia (AML) with MLL gene rearrangements demonstrate unique gene expression profiles driven by MLL-fusion proteins. Here, we identify the circadian clock transcription factor SHARP1 as a novel oncogenic target in MLL-AF6 AML, which has the worst prognosis among all subtypes of MLL rearranged AMLs. SHARP1 is expressed solely in MLL-AF6 AML, and its expression is regulated directly by MLL-AF6 / DOT1L. Suppression of SHARP1 induces robust apoptosis of human MLL-AF6 AML cells. Genetic deletion in mice delays the development of leukemia and attenuated leukemia-initiating potential, while sparing normal hematopoiesis. Mechanistically, SHARP1 binds to transcriptionally active chromatin across the genome and activates genes critical for cell survival as well as key oncogenic targets of MLL-AF6. Our findings demonstrate the unique oncogenic role for SHARP1 in MLL-AF6 AML. Overall design: ChIP-seq and RNA-seq using ML-2 cells. ChIP-seq using SHI1 cells.
Project description:The purpose of this study is to investigate the transcriptional programs as it relates to disease latency initiated by different MLL fusion proteins, including: MLL-AF1p, MLL-AF6, MLL-Gas7, MLL-AF9 and MLL-ENL. Leukemia cell lines were established by transforming kit+ mouse bone marrow cells with retroviruses coding MLL-AF1p, MLL-AF6, MLL-Gas7, MLL-AF9 or MLL-ENL. At early phase after the cell lines were established, cells growing at exponential phase (cell density at 0.5~1x106/ml) were harvested for RNA extraction and sequencing purpose. Sequencing is performed on total RNA isolated from mouse leukemia cell lines generated from kit+ mouse bone marrow cells transduced with various MLL fusion proteins and is compared to control total RNA isolated from kit+ mouse bone marrow cells.
Project description:Leukemia cells from mice with MLL-AF10 AML were fractionated into separate sub-populations on the basis of c-kit expression, which correlates with MLL LSC frequency (Somervaille and Cleary, 2006). The sorted AML sub-populations exhibited substantial differences in their frequencies of AML CFCs/LSCs (mean 14-fold) and morphologic features, consistent with a leukemia cell hierarchy with maturation through to terminally differentiated neutrophils. Overall design: Leukemic splenocytes from four mice with MLL-AF10 AML were sub-fractionated in to c-kit high and c-kit negative sub-populations by FACS.
Project description:Acute Myeloid Leukemia (AML) is associated with a number of genetic and epigenetic events that result in malignant transformation of hematopoietic cells. In particular, transcription factors essential for normal hematopoiesis and stem cell function are often found mutated leading to the formation of leukemic stem cells and the accumulation of immature blasts. Among them, translocations involving the mixed lineage leukemia (MLL) gene at chromosome band 11q23 are one of the most commonly events (~10 %) and is associated with poor prognosis in human leukemias. Whereas the downstream effects of MLL-fusion proteins are well established, the modes on which these effects are mediated are still unclear and whether MLL-fusion proteins are dependent on other transcriptional regulators or act alone remains elusive. To investigate this we searched gene expression profiles from patients with MLL-rearranged AML compared with normal hematopoietic progenitor cells for transcriptional regulators and found targets of C/EBPα to be up-regulated in the AML samples, suggesting that C/EBPα might collaborate with MLL-fusion proteins in the initial transformation process. We could show that transformation by MLL-fusion proteins is dependent on C/EBPα activity both in early progenitors as well as in GMPs. In contrast, C/EBPα was found to be indispensable in an already established leukemia. These finding led us to study the early transcriptional changes induced by MLL-ENL expression and we identified a combined C/EBPα / MLL-ENL transcriptional signature. Collectivly, our data shows that C/EBPα configure a proper chromatin state required for MLL-fusions to induce malignant transformation. Histone modification profiles (H3K4me3 and H3K27me3) in haematopoietic progenitor cells (preGM, wild type and Cebpa knock out), and C/EBPα binding in GMP cells
Project description:The genetic programs that promote retention of self-renewing leukemia stem cells (LSCs) at the apex of cellular hierarchies in acute myeloid leukemia (AML) are not known. In a mouse model of human AML, LSCs exhibit variable frequencies that correlate with the initiating MLL oncogene and are maintained in a self-renewing state by a transcriptional sub-program more akin to that of embryonic stem cells (ESCs) than adult stem cells. The transcription/chromatin regulatory factors Myb, Hmgb3 and Cbx5 are critical components of the program and suffice for Hoxa/Meis-independent immortalization of myeloid progenitors when co-expressed, establishing the cooperative and essential role of an ESC-like LSC maintenance program ancillary to the leukemia initiating MLL/Hox/Meis program. Enriched expression of LSC maintenance and ESC-like program genes in normal myeloid progenitors and poor prognosis human malignancies links the frequency of aberrantly self-renewing progenitor-like cancer stem cells to prognosis in human cancer. Overall design: Samples are from five separate cohorts of mice where leukemia was initiated using distinct MLL fusion oncogenes: MLL-AF1p (n=9), MLL-AF10 (n=8), MLL-GAS7 (n=5), MLL-AF9 (n=5) and MLL-ENL (n=7). Four normal BM samples were also used as controls.
Project description:Leukemia cells from mice with MLL-AF10 AML were fractionated into separate sub-populations on the basis of c-kit expression, which correlates with MLL LSC frequency (Somervaille and Cleary, 2006). The sorted AML sub-populations exhibited substantial differences in their frequencies of AML CFCs/LSCs (mean 14-fold) and morphologic features, consistent with a leukemia cell hierarchy with maturation through to terminally differentiated neutrophils. Experiment Overall Design: Leukemic splenocytes from four mice with MLL-AF10 AML were sub-fractionated in to c-kit high and c-kit negative sub-populations by FACS.