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Genomic lesions in CLL: B-CLL vs. PMNs from respective patients

ABSTRACT: We examined copy number changes in the genomes of B cells from 58 patients with chronic lymphocytic leukemia (CLL) using representational oligonucleotide microarray analysis (ROMA), a form of comparative genomic hybridization (CGH), at a resolution exceeding previously published studies. We observed at least one genomic lesion in each CLL sample and considerable variation in the number of abnormalities from case to case. Virtually all abnormalities previously reported were also observed here, most of whichwere indeed highly recurrent. We observed the boundaries of known events with greaterclarity and identified previously undescribed lesions, some of which were recurrent. Weprofiled the genomes of CLL cells separated by the surface marker CD38, and foundevidence of distinct subclones of CLL within the same patient. We discuss the potential applications of high resolution CGH analysis in a clinical setting. Keywords: Genetic modification, polymorphonuclear cell (PMN)

ORGANISM(S): Homo sapiens

PROVIDER: GSE12794 | GEO | 2008/10/01

SECONDARY ACCESSION(S): PRJNA112791

REPOSITORIES: GEO

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Novel SF3B1 Deletion Mutations Result in Aberrant RNA Splicing in CLL Patients

Project description:Recurrent mutations in RNA splicing factors SF3B1, U2AF1, and SRSF2 have been reported in hematologic cancers including myelodysplastic syndromes (MDS) and chronic lymphocytic leukemia (CLL). However, SF3B1 is the only splicing associated gene to be found mutated in CLL and has been shown to induce aberrant splicing. To investigate if any other genomic aberration caused similar transcriptome changes, we clustered RNASeq samples based on an alternative 3’ splice site (ss) pattern previously identified in SF3B1-mutant CLL patients. Out of 215 samples, we identified 37 (17%) with alternative 3’ ss usage, the majority of which harbored known SF3B1 hotspot mutations. Interestingly, 3 patient samples carried previously unreported in-frame deletions in SF3B1 around K700, the most frequent mutation hotspot. To study the functional effects of these deletions, we used various minigenes demonstrating that recognition of canonical 3’ ss and alternative branchsite are required for aberrant splicing, as observed for SF3B1 p.K700E. The common mechanism of action of these deletions and substitutions result in similar sensitivity of primary cells towards splicing inhibitor E7107. Altogether, these data demonstrate that novel SF3B1 in-frame deletion events identified in CLL result in aberrant splicing, a common biomarker in spliceosome-mutant cancers.

2017-06-27 | GSE95352 | GEO

Chromatin profiling of CLL cells with hyperactivated Notch1 compared to control CLL cells [ATAC-seq]

Project description:NOTCH1 gain-of-function mutations are recurrent in B cell chronic lymphocytic leukemia (B-CLL), where they are associated with accelerated disease progression and refractoriness to chemotherapy. The specific role of NOTCH1 in the development and progression of this malignancy is unclear. Herein we assess the impact of loss of Notch signaling and pathway hyperactivation in an in vivo mouse model of CLL (IgH.TEm) that faithfully recapitulates many features of the human pathology. Ablation of canonical Notch signaling using conditional gene inactivation of RBP-J in immature hematopoietic or B cell progenitors delayed CLL induction and reduced incidence of mice developing disease. In contrast, forced expression of a dominant active form of Notch resulted in more animals developing CLL with early disease onset. Comparative analysis of gene expression and epigenetic features of Notch gain-of-function and control CLL cells revealed direct and indirect regulation of cell cycle-associated genes, which led to increased proliferation of Notch gain-of-function CLL cells in vivo. These results demonstrate that Notch signaling facilitates disease initiation and promotes CLL cell proliferation and disease progression.

2020-12-19 | GSE160508 | GEO

Gene expression profiling of CLL cells with hyperactivated Notch1 compared to control CLL cells [RNA-seq]

2020-12-19 | GSE147836 | GEO

Transcription profiling of mouse model of CLL in Em-TCL1 mice provides a biologically relevant model to unravel and reverse immune deficiency in human cancer.

Project description:Immune deficiency is common in cancer, but the biological basis for this and ways to reverse it remains elusive. Here we present a mouse model of B cell chronic lymphocytic leukemia (CLL) that recapitulates changes in the non-malignant circulating T cells seen in patients with this illness.1 To validate this model, we examined changes in T cell gene expression, protein expression and function in Em-TCL1 transgenic mice as they developed CLL 2,3 and demonstrate that development of CLL in these transgenic mice is associated with changes in impaired T cell function and in gene expression in CD4 and CD8 T cells similar to those observed in patients with this disease. Infusion of CLL cells into non-leukemia bearing Em-TCL1 mice rapidly induces these changes, demonstrating a causal relationship between leukemia and the induction of T cell changes. This model allows dissection of the molecular changes induced in CD4 and CD8 T cells by interaction with leukemia cells and further supports the concept that cancer results in complex abnormalities in the immune microenvironment. Gene expression profiling was performed to determine whether Em-TCL1 murine model of chronic lymphocytic leukemia (CLL) mimics T cell defects induced by CLL cells in patients with CLL. Experiment Overall Design: CD4 T cells and CD8 T cells were obtained from spleens of B6C3 and Em-TCL1 transgenic murine model of CLL or from peripheral blood mononuclear cells of previously untreated patients with CLL and healthy individuals (Pubmed ID: 15965501). Gene expression profiling was performed using total RNA and the data were analysed to compare gene expression profile of CLL to healthy within or between the species.

2008-06-17 | E-GEOD-8836 | biostudies-arrayexpress

RBPJ and H3K27ac chromatin IP with sequencing of CLL cells with hyperactivated Notch1 compared to control CLL cells [ChIP-seq]

2020-12-19 | GSE160510 | GEO

CLL Patients

Project description:Genomic profiles of CLL (Chronic Lymphocytic Leukemia) patients. 11 CLL patients were selected for detection of genomic aberrations, 8 patients with atypical CLL and 3 patients with typical CLL.

2009-12-16 | GSE19458 | GEO

Expression data from healthy and malignant (chronic lymphocytic leukemia, CLL) human B-lymphocytes after B-cell receptor stimulation

Project description:Three different cell populations (6 healthy B-lymphocytes, 6 leukemic CLL B-lymphocyte of indolent form and 5 leukemic CLL B-lymphocyte of aggressive form) were stimulated in vitro with an anti-IgM antibody, activating the B-cell receptor (BCR). We analyzed the gene expression at 4 time points (60, 90, 210 and 390 minutes). Each gene expression measurement is performed both in stimulated cells and in control unstimulated cells. For one aggressive CLL case, we silenced expression of DUSP1 by transfecting DUSP1-specific RNAi and, as a control, transfected cells with a non-targeting RNAi. We then stimulated the BCR of these cells and analyzed the gene expression at the same time points in stimulated cells and in control unstimulated cells. B-cells were negatively selected from healthy donors and previously untreated CLL patients. BCR stimulated and unstimulated control B-cells were treated at four time points after stimulation for total RNA extraction and hybridization on Affymetrix microarrays.

2013-01-04 | E-GEOD-39411 | biostudies-arrayexpress

CLL in Em-TCL1 mice provides a biologically relevant model to unravel and reverse immune deficiency in human cancer.

Project description:Immune deficiency is common in cancer, but the biological basis for this and ways to reverse it remains elusive. Here we present a mouse model of B cell chronic lymphocytic leukemia (CLL) that recapitulates changes in the non-malignant circulating T cells seen in patients with this illness.1 To validate this model, we examined changes in T cell gene expression, protein expression and function in Em-TCL1 transgenic mice as they developed CLL 2,3 and demonstrate that development of CLL in these transgenic mice is associated with changes in impaired T cell function and in gene expression in CD4 and CD8 T cells similar to those observed in patients with this disease. Infusion of CLL cells into non-leukemia bearing Em-TCL1 mice rapidly induces these changes, demonstrating a causal relationship between leukemia and the induction of T cell changes. This model allows dissection of the molecular changes induced in CD4 and CD8 T cells by interaction with leukemia cells and further supports the concept that cancer results in complex abnormalities in the immune microenvironment. Gene expression profiling was performed to determine whether Em-TCL1 murine model of chronic lymphocytic leukemia (CLL) mimics T cell defects induced by CLL cells in patients with CLL. Keywords: comparative gene expression profiling analysis.

2007-12-01 | GSE8836 | GEO

Normal karyotype CLL show high rate of SF3B1 mutations and genomic arrays aberrations with impact on time to treatment

Project description:Chronic Lymphocytic Leukemia (CLL) is a heterogeneous disease with a variable clinical course strictly dependent on cytogenetic and molecular features. However, in 15-20% of cases both conventional cytogenetic and FISH analyses do not show any kind of abnormality. With the aim to identify dependable molecular prognostic factors in this subgroup, we evaluated 171 CLL patients, without aberrations detected by chromosome banding and FISH analysis. A comprehensive analysis was performed including genomic arrays (CGH+SNP), IGHV status, flow cytometry and a targeted sequencing. By genomic arrays, we detected 73 aberrations in 39 patients (23%). Most frequently, patients had 1 aberration (25/171; 15%), while 14 patients (8%) had at least 2 aberrations. IGHV unmutated status was present in 53/171 (31%) patients. SF3B1 was the most frequently mutated gene (26/171 patients; 15%), followed by NOTCH1 (n=15, 9%), ATM (n=5; 3%); TP53 (n=5; 3%); KLHL6 (n=5; 3%); MYD88 (n=5; 3%) and XPO1 (n=5; 3%). At univariate analysis, an adverse impact on time to treatment (TTT) was evident for SF3B1 mutations, higher white blood cell count, higher CLL cells percentage by flow cytometry, CD38 positivity, IGHV unmutated status and at least 2 genomic array abnormalities. Of them, SF3B1 mutations, CLL cells percentage, IGHV unmutated status and number of genomic array aberrations maintained their impact in multivariate analysis. In conclusion, integrating genomic and molecular data, we identified patients at higher risk for treatment need. Therefore, we suggest to evaluate these factors for a better prognostic stratification of normal karyotype CLL subset.

2017-08-31 | GSE103306 | GEO

Genomic Alterations in High-risk CLL Frequently Affect Cell Cycle Key Regulators and NOTCH1‑regulated Transcription.

Project description:To identify genomic alterations contributing to the pathogenesis of high‑risk chronic lymphocytic leukemia (CLL) beyond the well‑established role of TP53 aberrations, we comprehensively analyzed 146 high‑risk CLL cases by single‑nucleotide polymorphism (SNP)‑arrays and targeted next‑generation sequencing including 75 relapsed/refractory and 71 treatment‑naïve high‑risk cases from prospective clinical trials. Increased genomic complexity was a hallmark of relapsed/refractory and treatment‑naïve high‑risk CLL, and was associated with TP53 and ATM dysfunction. In relapsed/refractory cases previously exposed to the selective pressure of chemo(immuno)therapy, gain(8)(q24.21) and del(9)(p21.3) were found particularly enriched. Both of these copy number alterations (CNAs) affected key regulators of cell cycle progression, namely c‑MYC and CDKN2A/B. Gains in 8q24.21 were either focal gains in a c‑MYC enhancer region or larger gains directly affecting the c‑MYC locus, but only the latter type was highly enriched in relapsed/refractory CLL (17%). Loss of CDKN2A/B was found frequently to co‑occur with gain of c‑MYC and in this combination it was likely associated with Richter transformation. In addition to a high frequency of NOTCH1 mutations (23%), we found recurrent genetic alterations in SPEN (4% mutated), RBPJ (8% deleted) and SNW1 (8% deleted), all affecting a protein complex that represses transcription of NOTCH1 target genes. We investigated the functional impact of these alterations on HES1, DTX1 and c‑MYC gene transcription and found de‑repression of these NOTCH1 target genes particularly with SPEN mutations. In summary, we provide new insights into the pathogenesis of high‑risk CLL by defining novel recurrent CNAs and identifying alterations that likely contribute to disease refractoriness.

2020-05-06 | GSE131114 | GEO

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