Transcriptional response in acute lymphoblastic leukaemia cells to bone marrow microenvironment
ABSTRACT: Glucocorticoids (GCs) and topoisomerase II inhibitors are used in the treatment of acute lymphoblastic leukaemia (ALL) due to their ability to induce cell death in lymphoid cells. GC-induced apoptosis is mediated by the glucocorticoid receptor (GR), whereas topoisomerase II inhibitors cause DNA damage and activate sensors of DNA damage including the tumour suppressor p53. In order to shed light on the role of the microenvironment in cell death and identify determinants of drug sensitivity we performed transcriptomic analysis in ALL cells treated with the synthetic glucocorticoid dexamethasone, and the topoisomerase II inhibitor etoposide combined with bone marrow-derived conditioned media (CM).
Project description:Stem cells reside in specific niches providing stemness-maintaining environments. Thus, the regulated migration from these niches is associated with differentiation onset. However, mechanisms retaining stem cells in their niche remain poorly understood. Here, we show that the epigenetic regulator lysine-specific demethylase 1 (Lsd1) organises the trophoblast niche of the early mouse embryo by coordinating migration and invasion of trophoblast stem cells (TSCs). Lsd1 deficiency leads to the depletion of the stem cell pool resulting from precocious migration of TSCs. Migration is induced by premature expression of the transcription factor Ovol2 that is repressed by Lsd1 in undifferentiated wild-type TSCs. Increasing Ovol2 levels suffices to recapitulate the migration phenotype. Furthermore, Lsd1-deficient TSCs exhibit a developmental bias towards cells of the syncytiotrophoblast and impaired spongiotrophoblast and trophoblast giant cell differentiation. In summary, we describe that the epigenetic modifier Lsd1 coordinates placental development by retaining TSCs in their niche and directing trophoblast differentiation. Mouse trophoblast stem cells (TSCs) were isoloated from a single conditional Lsd1-deficient mouse (Lsd1tm1Schüle). Deletion of Lsd1 was induced eight days before the collection of RNA by addition of 0.2 µM 4OH-tamoxife. Cells were isolated at successive stages of differentiation for total RNA extraction and hybridization on Affymetrix microarrays. To that end, we harvested cells at three time-points: before induction of differentiation (d0), two days after induction of differentiation (d2), and four days after induction of differentiation (d4). Three replicates (1, 2, 3) for control (-) and Lsd1-deficeint (+) cells were included for each differentiation stage.
Project description:Gene expression profiling has demonstrated clinical utility as a predictive tool in clinical oncology. We have identified genes associated with invasion of pancreatic cancer, and with potential for identifying early recurrence. We used Affymetrix Human U133 Plus 2.0 microarrays to identifiy specific predictive profiles in pancreatic cancer, and the evolution of gene expression. We identified distinct classes of up-regulated genes during this process. Primary and metastatic pancreatic cancer cell lines (BxPC-3 and AsPC-1), were stimulated with with phorbol-12-myristate 13-acetate (PMA), a known inducer of invasion. Affymetrix gene expression microarray analysis was performed, comparing PMA stimulated BxPC-3 and AsPC-1 gene expression to unstimulated controls, and also PMA stimulated BxPC-3 verses stimulated AsPC-1 cell lines. Differential gene expression was identified using ArrayAssist bioinformatics software. Gene expression changes were confirmed using quantitative reverse transcription polymerase chain reaction (qRT-PCR) (Assays-on-demand, Taqman, ABI systems). Pathway Assist and GOstat were used to identify pathway and gene ontology changes.
Project description:The tumor suppressor and deubiquitinase (DUB) BAP1 regulates chromatin-associated processes and is frequently mutated in various malignancies. BAP1 and its drosophila orthologue Calypso assemble DUB complexes with ASXL-1, -2, -3 paralogues and ASX respectively, and these cofactors are required for stimulating their DUB activity. However how the DUB activity of BAP1 is regulated remains largely unknown. Here we show that BAP1 promotes monoubiquitination of ASXLs on the ASXM/DEUBAD domain. ASXL2 monoubiquitination promotes its stability or proteasomal degradation, stimulates BAP1 DUB activity and is required for mammalian cell proliferation. Monoubiquitination of ASXL2 is directly catalyzed by UBE2E family of ubiquitin conjugating enzymes and is regulated by deubiquitination. Monoubiquitination of ASX is regulated by Calypso and is required for drosophila development. We further revealed a switch mechanism that tightly regulate BAP1 function, as a monoubiquitination of BAP1 UCH domain is mutually exclusive with ASXL2 monoubiquitination, thus ensuring highly coordinated DUB-mediated signaling.
Project description:Germ cell tumours (GCTs) are a complex group of malignancies. They are unique in developing from a pluripotent progenitor cell. The initial lesion is believed to be the relatively benign precursor lesion (ICGNU), from which either highly chemosensitive seminomas or the more aggressive non-seminomas develop. Previous analyses of selected genes have suggested that non-seminomas exhibit much higher levels of DNA methylation than seminomas. However, the genomic targets that are methylated, the extent to which this results in gene silencing and the identity of the silenced genes most likely to play a role in the tumours’ biology have not yet been established. Here genome-wide methylation and expression analysis of GCT cell lines was combined with gene expression data. This demonstrated that the seminoma cells exhibited very little aberrant DNA methylation while non-seminoma cells exhibited very high levels of DNA methylation. Large differences in the level of methylation of the CpG islands of individual genes between tumour cell lines correlated well with differential gene expression. Treatment of non-seminoma cells with 5-aza-2-deoxycytidine verified that methylation of all genes tested did indeed play a role in their silencing and many of these genes were also differentially expressed in primary tumours. Through this approach the genes silenced in the various GCT cell lines were identified. Conclusions: Several pluripotency-associated genes, never before implicated in this type of cancer, were identified as a major functional group of silenced genes. Silencing of these factors that normally suppress somatic differentiation might play an important role in the progression to non-seminoma formation. Genomic DNA and RNA was extracted from cell lines representing four subtypes of GCT. RNA was subjected to Affymetric expression array analysis while DNA was bisulfite treated and analysed using Illumina Infinium 450K arrays. Statistical approaches were used to correlate methylation and expression for each gene.
Project description:DNA topoisomerase II (topo II) catalyzes a strand passage reaction in that one duplex is passed through a transient brake in another. Completion of late stages of neuronal development depends on the presence of active isoform (topo IIbeta). We identified topo IIbeta action sites on 7 selected genomic regions (about 79 Mb in total), each containing at least one gene that is controlled by topo IIbeta in neuronal differentiation. We used a novel method, etoposide-mediated topoisomerase immunoprecipitation (eTIP), followed by identification of precipitated DNA fragments on genomic tiling arrays. These DNA fragments were first fractionated by concentrated salt prior to the array analysis. The 0.5 M NaCl-released fraction was analyzed as P2 and the salt-resistant fraction wad analyzed as P1. The genomic DNA fractions from the immunoprecipitate (P1 or P2) were co-hybridized with a reference DNA isolated from the input of immunoprecipitation.
Project description:One major class of anti-cancer drugs targets topoisomerase II to induce DNA double-strand breaks and cell death of fast growing cells. In vitro experiments showed that doxorubicin can induce histone eviction as well as DNA damage, while etoposide can only induce DNA damage. Here, we compare the transcription responses of different tissues to doxorubicin or etoposide treatment in vivo. Total RNA from respective tissues in FVB mice 1 day or 6 days post indicated drug treatment were extracted and compared to un-treated mice. Two mice were used for each treatment.
Project description:Background: Clear guidelines for therapy of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) are missing due to the lack of randomized double-blind controlled clinical trials. Moderate yet similar clinical benefit has been demonstrated for IFN-a monotherapy and high-dose ascorbic acid (AA) monotherapy in open clinical trials. However, there is no clear evidence to support the value of one of these specific treatment approaches, due to the lack of in vivo and in vitro studies exploring and comparing the effects of high-dose AA and IFN-a treatment in the context of HAM/TSP. Principal Findings: Based on flow cytometry and thymidine incorporation, we demonstrated for the first time that high-dose AA displays superior antiproliferative and immunomodulatory effects over IFN-a in HAM/TSP PBMCs ex vivo. In addition, high-dose AA induces cell death in HTLV-1-infected T-cell lines in vitro. Microarray combined with Ingenuity Pathway Analysis revealed AA-induced modulation of genes associated with cell death and cell cycle. Conclusions: In comparison with IFN-a, high-dose AA is preferred as anti-HTLV-1 treatment in vitro, due to its superior cell death-inducing, antiproliferative and immunomodulatory effects. Considering the lack of treatment options, the mild in vivo side effects and the low cost price, high-dose AA should be further explored for its therapeutic potential in HAM/TSP treatment. In total, 15 samples were analyzed. One microarray experiment was performed, including triplicate samples for each treatment condition (untreated, IFN-a, 10 µg/ml ascorbic acid, 50 µg/ml ascorbic acid, 100 µg/ml ascorbic acid). Triplicate samples were obtained from three separate RNA experiments.
Project description:The purpose of experiment is to compare the mRNA expression differences between HeLa cells conditioned with normoxia 21% oxygen and hypoxia 1% oxygen at 6h and 20h. Total RNA was obtained from HeLa cells for 4 different conditions, 3 biological replicate experiments were performed, resulting in a total of 12 samples.