Project description:We recently identified recurrent mutations of cohesin complex in myeloid neoplasms through whole-exome sequencing analysis. RAD21 is one of the main components of the cohesin complex. In this study, to investigate the biological impact of wild-type RAD21 on Kasumi1 cells harboring RAD21 mutation, Kasumi1 cells were retrovirally transduced with either mock or wild-type RAD21, and expression array was performed. Expression analysis was performed for mock- or wild-type RAD21-transduced Kasumi-1 cells in triplicate. The experiment was performed twice independently.
Project description:We recently identified recurrent mutations of cohesin complex in myeloid neoplasms through whole-exome sequencing analysis. RAD21 is one of the main components of the cohesin complex. In this study, to investigate the biological impact of wild-type RAD21 on Kasumi1 cells harboring RAD21 mutation, Kasumi1 cells were retrovirally transduced with either mock or wild-type RAD21, and expression array was performed.
Project description:We recently identified recurrent mutations of cohesin complex in myeloid neoplasms through whole-exome sequencing analysis. In this study, we performed SNP array analysis to detect abnormal copy number of the cohesin genes. Copy number analysis by Affymetrix 50K or 250K SNP arrays was performed for 93 AML and 70 MDS tumor samples.
Project description:We recently identified recurrent mutations of cohesin complex in myeloid neoplasms through whole-exome sequencing analysis. In this study, we performed SNP array analysis to detect abnormal copy number of the cohesin genes.
Project description:Genome compartmentalization mediated by the cohesin complex plays an essential role in the maintenance of genome integrity and transcriptional regulation. Recurrent somatic mutations in multiple members of the cohesin complex are frequent genetic drivers in several types of cancer, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), but the cellular consequences of cohesin mutations have not been determined and no therapies have been identified with selective efficacy in cohesin-mutant cancers. Using quantitative proteomics and genome-wide genetic screens in genetically engineered models of STAG2-mutant AML, we identify changes in cohesin complex composition and dependency on STAG1, DNA damage repair, master transcription factors, and RNA splicing machinery. Consistent with these findings, loss of STAG2 leads to DNA replication fork stalling and is associated with increased levels of dsDNA breaks and activation of DNA damage checkpoints, as well as aberrant splicing. Genetic or pharmacologic perturbation of DNA damage repair or splicing creates a synthetic vulnerability for cohesin-mutant cells in vitro and in vivo. Finally, STAG2 loss leads to a global reduction in cohesin binding to chromatin and expansion of super-enhancers, and mutant cohesin complexes spatially co-localize with super-enhancer enriched factors, DNA damage and splicing machinery. Our findings inform the biology of cohesins in cancer cells, and highlight novel therapeutic possibilities for cohesin-mutant malignancies.
Project description:Recurrent somatic ASXL1 mutations occur in patients with myelodysplasia (MDS), myeloproliferative neoplasms (MPN), and acute myeloid leukemia (AML), and are associated with adverse outcome. Despite the genetic and clinical data implicating ASXL1 mutations in myeloid malignancies, the mechanisms of transformation by ASXL1 mutations are not understood. Here we identify that ASXL1 mutations result in loss of PRC2-mediated histone H3 lysine 27 (H3K27) tri-methylation. Through integration of microarray data with genome-wide histone modification ChIP-Seq data we identify targets of ASXL1 repression including the posterior HOXA cluster that is known to contribute to myeloid transformation. We demonstrate that ASXL1 associates with the Polycomb repressive complex 2 (PRC2), and that loss of ASXL1 in vivo collaborates with NRASG12D to promote myeloid leukemogenesis. To assess the genome-wide effects of ASXL1 loss on chromatin state we performed chromatin immunoprecipitation followed by next generation sequencing (CHIP-seq) for histone modifications known to be associated with PcG (histone H3 lysine 27 trimethylation (H3K27me3)) or TxG activity (histone H3 lysine 4 trimethylation (H3K4me3)) in UKE1 cells expressing empty vector (EV) or 2 independent validated shRNAs for ASXL1. This Series represents the ChIP-Seq data (not the microarray data referenced in the summary above). The related micorarray data are available in GEO as GSE38692.
Project description:The cohesin complex plays an essential role in chromosome maintenance and transcriptional regulation. Recurrent somatic mutations in the cohesin complex are frequent genetic drivers in cancer including myelodysplatic syndromes (MDS) and acute myeloid leukemia (AML). Here, using genetic dependency screens of STAG2-mutant AML, we identified DNA damage repair and replication as genetic dependencies in cohesin-mutant cells. We demonstrated increased levels of DNA damage and sensitivity of cohesin-mutant cells to PARP inhibition. We developed a mouse model of MDS in which Stag2 mutations arise as clonal secondary lesions in the background of clonal hematopoiesis driven by Tet2 mutations, and demonstrated selective depletion of cohesin-mutant cells with PARP inhibition in vivo. Finally, we demonstrated a shift from STAG2- to STAG1-containing cohesin complexes in cohesin-mutant cells, which is associated with longer DNA loop extrusion, more intermixing of chromatin compartments, and increased interaction with PARP and RPA proteins. Our findings inform the biology and therapeutic opportunities for cohesin-mutant malignancies.
Project description:Recurrent somatic ASXL1 mutations occur in patients with myelodysplasia (MDS), myeloproliferative neoplasms (MPN), and acute myeloid leukemia (AML), and are associated with adverse outcome. Despite the genetic and clinical data implicating ASXL1 mutations in myeloid malignancies, the mechanisms of transformation by ASXL1 mutations are not understood. Here we identify that ASXL1 mutations result in loss of PRC2-mediated histone H3 lysine 27 (H3K27) tri-methylation. Through integration of microarray data with genome-wide histone modification ChIP-Seq data we identify targets of ASXL1 repression including the posterior HOXA cluster that is known to contribute to myeloid transformation. We demonstrate that ASXL1 associates with the Polycomb repressive complex 2 (PRC2), and that loss of ASXL1 in vivo collaborates with NRASG12D to promote myeloid leukemogenesis.
Project description:<p>Patients with myeloid malignancies bearing high-risk cytogenetic abnormalities lack effective therapies and have a poor overall survival. -7/del(7q) is identified in half of high-risk myeloid neoplasms. We recently identified <i>CUX1</i> to be a haploinsufficient myeloid tumor suppressor gene located within the commonly deleted segment of 7q22. Here we identify the spectrum of somatic mutations that co-occur with loss of <i>CUX1</i> and chromosome 7 in patients with <i>de novo</i> acute myeloid leukemia (AML) or a therapy-related myeloid neoplasm. -7/del(7q) leukemias have a distinct mutational profile characterized by low frequencies of alterations in major leukemogenic pathways, including genes encoding transcription factors, cohesin, and DNA-methylation-related proteins. In contrast, RAS pathway activating mutations occurred in 40% of -7/del(7q) samples, a significantly higher frequency than other AMLs and higher than previously reported. As targeted therapeutics advance, our data provide guidance for which pathways are most relevant in the treatment of adverse-risk myeloid leukemia. </p>