Project description:The DNA Double-Strand Break Response Is Abnormal in Myeloblasts From Patients With Therapy-Related Acute Myeloid Leukemia [Affymetrix]
Project description:The DNA Double-Strand Break Response Is Abnormal in Myeloblasts From Patients With Therapy-Related Acute Myeloid Leukemia [NimbleGen]
Project description:Loss of chromosome 7 and del(7q) [-7/del(7q)] are recurring cytogenetic abnormalities in hematologic malignancies, including acute myeloid leukemia and therapy-related myeloid neoplasms, and associated with an adverse prognosis. We performed SNP array analysis on de novo and therapy-related myeloid neoplasms and identified a 2.17 Mb commonly deleted segment on chromosome band 7q22.1 containing CUX1, a gene encoding a homeodomain-containing transcription factor. Haploinsufficiency of the highly conserved ortholog, cut, led to hemocyte overgrowth and tumor formation in Drosophila melanogaster. Similarly, haploinsufficiency of CUX1 gave human hematopoietic cells a significant engraftment advantage upon transplantation into immunodeficient mice. These data identify CUX1 as a conserved, haploinsufficient tumor suppressor frequently deleted in myeloid neoplasms. We performed SNP-array analysis of 34 primary patient samples with de novo or therapy-related myeloid leukemia and one acute myeloid leukemia cell line, UoCM1. For patient samples, DNA was obtained from the white blood cells of bone marrow or peripheral blood leukemia specimens. Cytogenetic analysis revealed clonal -7/del(7q) in 17 of the cases.
Project description:Azacitidine (AZA) is a hypomethylating drug used to treat disorders associated with myelodysplasia and related neoplasms. Approximately 50% of patients do not respond to AZA and have very poor outcomes. It is of great interest to identify predictive biomarkers for AZA responsiveness. Therefore, we searched for specific genes whose expression level was associated with response status.Using microarrays, we analyzed gene expression patterns in bone marrow CD34+ cells from 32 patients with myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia with myelodysplasia-related changes before AZA therapy. Total RNA was isolated from bone marrow CD34+ cells obtained from myelodysplasia and related neoplasms patients who underwent treatment with 5-azacytidine (AZA, Vidaza). Using Illumina Human HT-12 v. 4 microarrays, we assayed gene expression profiles in patient CD34+ cells before AZA treatment in order to collect basic data for search for markers of the prediction of therapy response.
Project description:Antibody-based therapy for cancer is now one of the most successful and important strategies for treating patients with hematological malignancies. However, the lack of efficient tumor-associated antigens restricts the targeting therapy of myeloid leukemia. Analysis of the gene expression proï¬les of primary bone marrow samples from human acute myeloid leukemia (AML) patients or healthy donors was to identify and expand novel targets for the treatment of myeloid leukemias. we found that epithelial cell adhesion molecule (EpCAM) is overexpressed in patients with AML. we analyzed the gene expression proï¬les of bone marrow mononuclear cells from 2 human acute myeloid leukemia (AML) patients and 2 healthy donors using an oligonucleotide microarray, to identify up-regulated genes in AML samples comparing with healthy tissues.
Project description:Azacitidine (AZA) is a hypomethylating drug used to treat disorders associated with myelodysplasia and related neoplasms. Approximately 50% of patients do not respond to AZA and have very poor outcomes. It is of great interest to identify predictive biomarkers for AZA responsiveness. Therefore, we searched for specific genes whose expression level was associated with response status.Using microarrays, we analyzed gene expression patterns in bone marrow CD34+ cells from 32 patients with myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia with myelodysplasia-related changes before AZA therapy.
Project description:To identify cooperating lesions in de novo and therapy-related acute myeloid leukemia (t-AML) with translocation t(9;11)(p22;q23) we performed high-resolution SNP-array profiling on 40 leukemia samples [de novo: n=22; t-AML: n=16; unknown: n=2]. A mean of 1.73 copy number alterations (CNAs)/case were identified with no differences between de novo and t-AML cases. We identified a novel minimally deleted region (MDR) at 7q36.1-q36.2 partly overlapping with a MDR previously identified in core-binding factor AML; MLL3 was the only gene affected in both regions. In addition, a recurrent gain was found at 13q21.33-q22.1 harboring the potential oncogene KLF5. Sequence/expression analysis of selected candidate genes revealed deregulated EVI1 at high frequency (50%). Copy-neutral loss-of-heterozygosity (CN-LOH) was absent in the paired cohort Further analysis of the candidate genes might provide novel insights into the pathogenesis of t(9;11) AML SNP genotyping was performed on 40 de novo and therapy-related MLL-MLLT3-rearranged acute myeloid leukemia samples; Germline control DNA from remission bone marrow or peripheral blood was available for paired analysis in 15 patients. Data were processed using reference alignment, dChipSNP and circular binary segmentation.
Project description:Transcription can pose a threat to genomic stability through the formation of R-loops that obstruct the progression of replication forks. R-loops are three-stranded nucleic acid structures formed by an RNA-DNA hybrid with a displaced non-template DNA strand. We developed RDProx to identify proteins that regulate R-loops in human cells. RDProx relies on the expression of the hybrid-binding domain (HBD) of Ribonuclease H1 (RNaseH1) fused to the ascorbate peroxidase (APEX2), which permits mapping of the R-loop proximal proteome using quantitative mass spectrometry. We associated R-loop regulation with different cellular proteins and identified a role of the tumor suppressor DEAD box protein 41 (DDX41) in opposing R-loop-dependent genomic instability. Depletion of DDX41 resulted in replication stress, double strand breaks and increased inflammatory signaling. Furthermore, DDX41 opposes accumulation of R-loops at gene promoters and its loss leads to upregulated expression of TGFβ and NOTCH signaling genes. Germline loss-of-function mutations in DDX41 lead to predisposition to acute myeloid leukemia (AML) in adulthood. We propose that accumulation of co-transcriptional R-loops, associated gene expression changes and inflammatory response contribute to the development of familial AML with mutated DDX41.
Project description:Azacytidine (AzaC) and decitabine (AzadC) are cytosine analogs that covalently trap DNA methyltransferases, which place the important epigenetic mark 5-methyl-2’-deoxycytidine by methylating 2’-deoxycytidine (dC) at the C5 position. AzaC and AzadC are used in the clinic as antimetabolites to treat myelodysplastic syndrome and acute myeloid leukemia and are explored against other types of cancer. Although their principal mechanism of action is known, the downstream effects of AzaC and AzadC treatment are not well understood and the cellular prerequisites that determine sensitivity towards AzaC and AzadC remain elusive. Here, we investigated the effects and phenotype of AzaC and AzadC exposure on the acute myeloid leukemia cell line MOLM-13. We found that while AzaC and AzadC share many effects on the cellular level, including decreased global DNA methylation, increased formation of DNA double strand breaks, transcriptional downregulation of important oncogenes and similar changes on the proteome level, AzaC failed in contrast to AzadC to induce apoptosis in MOLM-13. The only cellular marker that correlated with this clear phenotypical outcome was the level of hydroxy-methyl-dC, an additional epigenetic mark that is placed by TET enzymes and repressed in cancer cells. Whereas AzadC increased hmdC substantially in MOLM-13, AzaC treatment did not result in any increase at all. This suggests that hmdC levels in cancer cells should be monitored as a response towards AzaC and AzadC and considered as a biomarker to judge whether AzaC or AzadC lead to cell death in leukemic cells.