Unknown,Transcriptomics,Genomics,Proteomics

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C/EBPÎ± induces highly efficient macrophage transdifferentiation of selected B-lymphoma /leukemia cell lines and impairs their tumorigenicity

ABSTRACT: Earlier work demonstrated that the transcription factor C/EBPÎ± can convert immature and mature murine B lineage cells into functional macrophages. Testing >20 human lymphoma and leukemia B-cell lines, we found that most can be transdifferentiated at least partially into macrophage-like cells, provided that C/EBPÎ± is expressed at sufficiently high levels. A tamoxifen-inducible subclone of the Seraphina Burkitt lymphoma line, expressing C/EBPÎ±ER, could be efficiently converted into phagocytic and quiescent cells with a transcriptome resembling normal macrophages. The converted cells retained their phenotype even when C/EBPÎ± was inactivated, a hallmark of cell reprogramming. Interestingly, C/EBPÎ± induction also impaired the cells' tumorigenicity. Likewise, C/EBPÎ± efficiently converted a B- lymphoblastic leukemia cell line into macrophage-like cells, again dramatically impairing their tumorigenicity. Our experiments show that human cancer cells can be induced to transdifferentiate by C/EBPÎ± into seemingly normal cells at high frequencies and provide a proof of principle for a potential new therapeutic strategy to treat B-cell malignancies. Changes in gene expression during transdifferentiation of BLaER1 cells, comparing uninduced (0h) cells with cells treated with E2 for 3h, 6h, 9h, 12h, 18h, 24h, 36h, 48h, 72h, 120h or 168h. Primary human B-cells and macrophages were used as controls. 2 replicates each.

ORGANISM(S): Homo sapiens

SUBMITTER: Francesca Rapino

PROVIDER: E-GEOD-44700 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: MYC is a transcription factor encoded by the c-MYC gene (thereafter termed MYC). MYC is key transcription factor involved in many central cellular processes including ribosomal biogenesis. MYC is overexpressed in the majority of human tumours including aggressive B-cell lymphoma especially Burkitt's lymphoma. Although Burkitt's lymphoma is a highlight example for MYC overexpression due to a chromosomal translocation, no global analysis of MYC binding sites by chromatin immunoprecipitation (ChIP) followed by global next generation sequencing (ChIP-Seq) has been conducted so far in Burkitt's lymphoma. Methodology/Principal Findings: ChIP-Seq was performed with a MYC-specific antibody giving rise to 7,054 predicted MYC binding sites after bioinformatics analysis of a total of 19 million sequence reads. In line with previous findings, binding sites accumulate in gene sets known to be involved in the ribosomal biogenesis, histone acetyltransferase and methyltransferase complexes and the cell cycle demonstrating a regulatory role of MYC in these processes. Unexpectedly, MYC binding sites also accumulate in genes typically expressed in mature B-cells. To assess the functional consequences of altered MYC binding, the ChIP-Seq data were supplemented with siRNA mediated knock-downs of MYC in BL cell lines followed by gene expression profiling. Interestingly, amongst others, genes involved in B-cell function were up-regulated in response to MYC silencing. Conclusion/Significance: The 7,054 MYC-binding sites identified by our ChIP-Seq approach greatly extend the knowledge regarding MYC binding in Burkitt's lymphoma and sheds further light on the enormous complexity of the MYC regulatory network. Especially our observation that (i) many B-cell relevant genes are targeted by MYC and (ii) that MYC down-regulation leads to an up-regulation of B-cell genes highlights an interesting aspect of BurkittM-BM-4s lymphoma biology. [ChIP-Seq] Analysis of MYC DNA binding sites by ChiP-Seq in 5 BurkittM-BM-4s lymphoma cell lines (Raji, Ramos, Blue1, BL41, CA46) [mRNA expression profiling] siRNA-mediated knock-down of MYC was done employing the BL cell lines Raji, BL41 and Blue1 in order to detect MYC-driven gene expression changes. For this purpose, the cells were Amaxa-transfected using MYC smart pool siRNA and control siRNA (Thermo Scientific/Dharmacon, Erembodegem, Belgium), respectively.

Project description:Although therapy responsiveness to therapy in Burkitt lymphoma (BL) is high, relapsed disease and and chemoresistance remain a clinical challenge, and complete mechanisms underlying BL chemoresistance and how it can be circumvented is yet to be fully elucidated. In this study we present data showing that chymotrypsin-like serine proteases inhibitor Nα-tosyl-L-phenylalanine chloromethylketone (TPCK) and specific NF-κB inhibitor Bay-11 7082 can induce caspase-independent apoptosis in chemoresistant BL cells. We also demonstrate that both TPCK and Bay-11 7082-treatment leads to decreased NF-κB nuclear activity and that this is associated with sensitization of chemoresistant Burkitt lymphoma cells. Furthermore we investigated global transcriptional changes induced by Bay-11 7082 and TPCK in the DG-75 and Raji cell lines, respectively, by microarray analysis using Illumina BeadChips. TPCK-treatment of Raji and DG-75 cells resulted in 59 and 21 differently expressed genes, respectively, while Bay-11-treated Raji and DG-75 cells displayed 1403 and 8 differently expressed genes, respectively. Gene Ontology (GO) categorization confirmed enrichment of multiple GOs in Bay 11-treated Raji and DG-75 cells. Fifty percent of the 61 categories in Raji cells were categories sorting under Biological Processes and represented mostly increased gene expression. In DG-75 cells Bay-11 7082 induced significant gene ontology enrichment in only two categories, where the increased/decreased ratio was 1:1. Further unsupervised and supervised bioinformatics processing by Ingenuity Pathway Analysis indicated significant networks in response to TPCK and Bay 11 respectively, including association to NF-κB. Bay-11 7082 demonstrated deregulated NF-κB related members of receptor mediated cell death signaling, i.e TRAF2 and TRADD, as well as deregulated members of the NF-κB signaling pathway from the cytoplasmic compartment, i.e RELB, in Raji cells. Comparably NF-κB network analysis of Raji- and DG-75 cells treated with Bay-11 7082 and Raji cells treated with TPCK demonstrated deregulation of NF-κB target genes CD69 and IL8. These data indicates that NF-kB may play a role in overcoming chemoresistance in BL cells with defective classical apoptosis signaling. NF-κB network analysis of Raji- and DG-75 cells treated with Bay-11 7082 and Raji cells treated with TPCK

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C/EBPÎ± induces highly efficient macrophage transdifferentiation of selected B-lymphoma /leukemia cell lines and impairs their tumorigenicity

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