Project description:Gene expression analysis identified a MLL translocation-specific signature of differentially expressed genes discriminating ALL and AML with and without MLL rearrangements. Gene expression signatures of acute lymphoblastic and myeloblastic leukemia samples with and without MLL rearrangements were analyzed using paired supervised analyses. Experiment Overall Design: ALL and AML patients with and without MLL rearrangements have been studied using paired class comparison (SAM) and class prediction (PAM) analyses.
Project description:Gene expression analysis identified a MLL translocation-specific signature of differentially expressed genes discriminating ALL and AML with and without MLL rearrangements. Gene expression signatures of acute lymphoblastic and myeloblastic leukemia samples with and without MLL rearrangements were analyzed using paired supervised analyses.
Project description:Pediatric Acute Myeloid Leukemia (AML) is an aggressive and poor prognosis malignancy for which there are few effective targeted approaches, despite the numerous genetic alterations, including MLL gene rearrangements (MLL-r). The histone methyltransferase DOT1L is involved in supporting proliferation of MLL-r cells, for which a target inhibitor, Pinometostat, has been evaluated in a clinical trial recruiting pediatric MLL-r leukemic patients. However, modest clinical effects have been reported. Recent studies reported that additional leukemia subtypes lacking MLL-r are sensitive to DOT1L inhibition. Here we report that targeting DOT1L with Pinometostat sensitizes pediatric AML cells to further treatment with the multi-kinase inhibitor Sorafenib, irrespectively of MLL-r. DOT1L pharmacologic inhibition induces AML cell differentiation and modulated expression of genes with relevant roles in cancer development. Such modifications in transcriptional program impact on further treatments, inducing a strong sensitization to Sorafenib, with increased apoptosis and growth suppression of both AML cell lines and primary pediatric AML cells with diverse genotypes. We used microarrays to define differential regulation of gene expression in AML cell lines with or without MLL gene rearrangements following pharmacologic inhibition of DOT1L.
Project description:Contemporary treatment of pediatric acute myeloid leukemia (AML) requires the assignment of patients to specific risk groups. To explore whether expression profiling of leukemic blasts could accurately distinguish between the known risk groups of AML, we analyzed 130 pediatric and 20 adult AML diagnostic bone marrow or peripheral blood samples using the Affymetrix U133A microarray. Class discriminating genes were identified for each of the major prognostic subtypes of pediatric AML, including t(15;17)[PML-RARalpha], t(8;21)[AML1-ETO], inv(16) [CBFbeta-MYH11], MLL chimeric fusion genes, and cases classified as FAB-M7. When subsets of these genes were used in supervised learning algorithms, an overall classification accuracy of more than 93% was achieved. Moreover, we were able to use the expression signatures generated from the pediatric samples to accurately classify adult de novo AMLs with the same genetic lesions. The class discriminating genes also provided novel insights into the molecular pathobiology of these leukemias. Finally, using a combined pediatric data set of 130 AMLs and 137 acute lymphoblastic leukemias, we identified an expression signature for cases with MLL chimeric fusion genes irrespective of lineage. Surprisingly, AMLs containing partial tandem duplications of MLL failed to cluster with MLL chimeric fusion gene cases, suggesting a significant difference in their underlying mechanism of transformation. All the gene expression arrays are available through http://www.stjuderesearch.org/site/data/AML1/ in the original study (PMID:15226186). To study the RAS gene expression in the human AML patients, a total of 104 AML cases with known KRAS and NRAS status (including 72 gene expression arrays in the original study and 32 additional arrays acquired later on), as well as 4 CD34+ normal bone marrow cases deposited in GEO GSE33315, were including in this depository. Gene expression profiling was performed on 104 single diagnosis tumor samples and 4 CD34+ normal bone marrow samples
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
Project description:Acute myeloid leukemia (AML) with chromosomal rearrangements involving the H3K4 methyltransferase mixed-lineage leukemia (MLL) is an aggressive subtype with low overall survival. MLL rearrangements rapidly transform hematological stem and progenitor cell (HSPC) to leukemia stem cell (LSC). Bortezomib (Velcade) is used widely in hematological malignancies. However, it is still unknown whether bortezomib possesses anti-self-renewal and anti-leukemogenesis of LSC in AML with MLL rearrangements. Here, we found that bortezomib inhibited cell proliferation, induced apoptosis, and decreased colony formation in leukemic cell lines, primary AML blasts, and MLL-AF9-transformed murine leukemic blasts. Besides, bortezomib reduced the frequency and function of LSC, inhibited the progression, and prolonged
Project description:Rearrangements of the mixed lineage leukemia (MLLr) gene are frequently associated with both pediatric and adult leukemia. However, the treatment options for these aggressive MLLr leukemias are limited due to the genomic complexity and dynamics of 3D structure in oncogene transcription and leukemia development. Here, we use Micro-C and transcriptome profiling to examine the MLLr-driven aberrant 3D genome architecture in gene-edited MLL-AF9 AML samples with biologically matched healthy donors. Recurrent and MLLr-specific alterations in A/B compartments, topologically associating domains and chromatin loops were identified. RNA sequencing in the same AML samples also revealed extensive and recurrent MLLr-specific promoter–enhancer and promoter–silencer loops. Overall, this study highlights the critical regulatory elements and provides rational and effective targeting strategy in MLLr AML.
Project description:Rearrangements of the mixed lineage leukemia (MLLr) gene are frequently associated with both pediatric and adult leukemia. However, the treatment options for these aggressive MLLr leukemias are limited due to the genomic complexity and dynamics of 3D structure in oncogene transcription and leukemia development. Here, we use Micro-C and transcriptome profiling to examine the MLLr-driven aberrant 3D genome architecture in gene-edited MLL-AF9 AML samples with biologically matched healthy donors. Recurrent and MLLr-specific alterations in A/B compartments, topologically associating domains and chromatin loops were identified. RNA sequencing in the same AML samples also revealed extensive and recurrent MLLr-specific promoter–enhancer and promoter–silencer loops. Overall, this study highlights the critical regulatory elements and provides rational and effective targeting strategy in MLLr AML.
Project description:Contemporary treatment of pediatric acute myeloid leukemia (AML) requires the assignment of patients to specific risk groups. To explore whether expression profiling of leukemic blasts could accurately distinguish between the known risk groups of AML, we analyzed 130 pediatric and 20 adult AML diagnostic bone marrow or peripheral blood samples using the Affymetrix U133A microarray. Class discriminating genes were identified for each of the major prognostic subtypes of pediatric AML, including t(15;17)[PML-RARalpha], t(8;21)[AML1-ETO], inv(16) [CBFbeta-MYH11], MLL chimeric fusion genes, and cases classified as FAB-M7. When subsets of these genes were used in supervised learning algorithms, an overall classification accuracy of more than 93% was achieved. Moreover, we were able to use the expression signatures generated from the pediatric samples to accurately classify adult de novo AMLs with the same genetic lesions. The class discriminating genes also provided novel insights into the molecular pathobiology of these leukemias. Finally, using a combined pediatric data set of 130 AMLs and 137 acute lymphoblastic leukemias, we identified an expression signature for cases with MLL chimeric fusion genes irrespective of lineage. Surprisingly, AMLs containing partial tandem duplications of MLL failed to cluster with MLL chimeric fusion gene cases, suggesting a significant difference in their underlying mechanism of transformation. All the gene expression arrays are available through http://www.stjuderesearch.org/site/data/AML1/ in the original study (PMID:15226186). To study the RAS gene expression in the human AML patients, a total of 104 AML cases with known KRAS and NRAS status (including 72 gene expression arrays in the original study and 32 additional arrays acquired later on), as well as 4 CD34+ normal bone marrow cases deposited in GEO GSE33315, were including in this depository.