Project description:The ability of oncogenes to provoke cancer is harnessed by regulators that control cell proliferation or induce apoptosis, and bypass of these checkpoints is a hallmark of malignancies. Myc oncoproteins are overexpressed in ~70% of all cancers and induce numerous transcription targets that regulate cell growth, metabolism, and the ribosome machinery. We used the Eμ-Myc mouse model from which one can directly compare expression profiles of wild type versus Myc-expressing B220+ pre-malignant lymphocytes and also queried differences in gene expression that ensue following the neoplastic switch to lymphoma (Nilsson et al., 2005 - PMID:15894264 and Keller et al. 2010 - PMID:20598117). Wild type and precancerous Eμ-Myc transgenic B cells (from 4-6 week old littermates), and lymphomas from 13 independent Eμ-Myc mice were investigated. These samples were used for subsequent RNA purification, labeling and hybridization to MOE430A Affymetrix arrays.
Project description:We have made use of the Eμ-myc transgenic mouse, a model for the study of B-cell lymphoma development that is initiated through a defined genetic alteration, to explore the contributions of additional somatic alterations that contribute to the heterogeneity of the resulting tumors. As one example of such heterogeneity, we have focused on the observation that lymphomas develop in Eμ-myc mice with a variable time of onset. Twenty-five early-onset, 25 late-onset lymphomas and 10 normal samples were each assayed on an Affymetrix Mouse Genome 430 2.0 array. Keywords: Myc induced lymphomas with various time-of-onset
Project description:Long-range interactions of ribososomal DNA (rDNA) identified by 4C-seq in mouse wildtype, premalignant and malignant Eμ-Myc cells and tissue culture adapated Eμ-Myc-shUbtf and Eμ-Myc-LMP (empty vector) cells.
Project description:The ability of oncogenes to provoke cancer is harnessed by regulators that control cell proliferation or induce apoptosis, and bypass of these checkpoints is a hallmark of malignancies. Myc oncoproteins are overexpressed in ~70% of all cancers and induce numerous transcription targets that regulate cell growth, metabolism, and the ribosome machinery. We used the Eμ-Myc mouse model from which one can directly compare expression profiles of wild type versus Myc-expressing B220+ pre-malignant lymphocytes and also queried differences in gene expression that ensue following the neoplastic switch to lymphoma (Nilsson et al., 2005 - PMID:15894264 and Keller et al. 2010 - PMID:20598117).
Project description:Myc oncoproteins directly regulate transcription by binding to target genes, yet this only explains a fraction of the genes affected by Myc. mRNA turnover is controlled via AU-binding proteins (AUBPs) that recognize AU-rich elements (AREs) found within many transcripts. Analyses of precancerous and malignant Myc-expressing B cells revealed that Myc regulates hundreds of ARE-containing (ARED) genes and select AUBPs. Notably, Myc directly suppresses transcription of Tristetraprolin (TTP/ZFP36), an mRNA-destabilizing AUBP, and this circuit is also operational during B lymphopoiesis and IL7 signaling. Importantly, TTP suppression is a hallmark of cancers with MYC involvement, and restoring TTP impairs Myc-induced lymphomagenesis and abolishes maintenance of the malignant state. Further, there is a selection for TTP loss in malignancy; thus, TTP functions as a tumor suppressor. Finally, Myc/TTP-directed control of select cancer-associated ARED genes is disabled during lymphomagenesis. Thus, Myc targets AUBPs to regulate ARED genes that control tumorigenesis. Ex vivo Eμ-Myc lymphoma cells were infected with MSCV-I-dsRed2 (RFP) and FACS sorted for dsRed2+ cells. These cells were then infected with MSCV-TTP-I-GFP and FACS sorted for GFP expression (TTP-GFP- or TTP-GFP+). These cells were used for subsequent RNA purification, labeling and hybridization to MOE430 2.0 Affymetrix arrays.
Project description:We used array CGH data from Eµ-myc lymphomas to assess significant differences in DNA copy number variation between Cluster 1 and Cluster 2 lymphomas. When Eµ-myc mice had evidence of lymphoma and/or ill appearance, they were humanely sacrificed and dissected. Lymphoma tissue was obtained and flash frozen in liquid nitrogen. Later, lymphoma tissue was homogenized, and genomic DNA was extracted. Array CGH was performed on genomic DNA, with genomic DNA from normal background strain mice used as the reference.
Project description:'The REL gene, encoding the NF-κB subunit c-Rel, is frequently amplified in B-cell lymphoma and functions as a tumour promoting transcription factor. Here we report the surprising result that c-rel -/- mice display significantly earlier lymphomagenesis in the c-Myc driven, Eμ-Myc model of B-cell lymphoma. c-Rel loss also led to earlier onset of disease in a separate TCL1-Tg driven lymphoma model. Tumour reimplantation experiments indicated that this is an effect intrinsic to the Eμ-Myc lymphoma cells but, counter-intuitively, c-rel -/- Eμ-Myc lymphoma cells were more sensitive to apoptotic stimuli. To learn more about why loss of c-Rel led to earlier onset of disease, microarray gene expression analysis was performed on B-cells from 4-week old, wild type and c-rel -/- Eμ-Myc mice. Extensive changes in gene expression were not seen at this age but among those transcripts significantly downregulated by the loss of c-Rel was the B-cell tumour suppressor BTB and CNC homology 2 (Bach2). Q-PCR and western blot analysis confirmed loss of Bach2 in c-Rel mutant Eμ-Myc tumours at both 4 weeks and the terminal stages of disease. Moreover Bach2 expression was also downregulated in c-rel -/- TCL1-Tg mice and RelA Thr505Ala mutant Eμ-Myc mice. Analysis of wild type Eμ-Myc mice demonstrated that the population expressing low levels of Bach2 exhibited the earlier onset of lymphoma seen in c-rel-/- mice. Confirming the relevance of these findings to human disease, analysis of ChIP-Seq data revealed that Bach2 is a c-Rel and NF-κB target gene in transformed human B-cells, while treatment of Burkitt''s lymphoma cells with inhibitors of the NF-κB/IKK pathway or deletion of c-Rel or RelA resulted in loss of Bach2 expression. This data reveals a surprising tumour suppressor role for c-Rel in lymphoma development explained by regulation of Bach2 expression, underlining the context dependent complexity of NF-κB signalling in cancer.'
Project description:Analysis of Upstream Binding Transcription Factor (UBTF) binding patterns by ChIP-seq in mouse wildtype, premalignant and malignant Eμ-Myc cells.