Purpose: Seek for differential gene expression in vemurafenib-resistant A375 tumors vs. untreated controls to provide a rationale for resistance mechanism Methods: mRNA profiles of vemurafenib-resistant A375 tumors and untreated control tumors were generated by transcriptome sequencing of A375 melanoma bearing mice. Since our xenograft samples contain a mixture of human and mouse RNAs we mapped RNASeq reads against a hybrid human/mouse genome. We than removed reads of potential mouse origin by taking only reads that map uniquely to human chromosomes. On average 23% of reads were removed as potential mouse reads. We than took the remaining reads (on average 77% per sample) to determine the gene expression levels for each sample. Normalized expression levels of 5 resistant samples were compared to 4 untreated control samples to detect differnetially regulated genes which may contribute to vemurfenib resistance Results: Expression levels of several genes were consistently altered in all resistant samples. Expression of e.g. genes encoding SPRY2, SPRY4, DUSP6, CCND1, PIK3R3, FGFR1, EPHA4, MCL1, and IGF1R was down-regulated, whereas expression of PDGFC, VEGFC, ABCB9 and KITLG was increased. Conclusions: Our study reports several differentially expressed genes which may contribute to vemurafenib resistance in A375 tumor bearing mice Overall design: RNA sequencing of genes expressed in A375 tumors bearing mice treated with vemurafenib until in vivo resistance appeared vs. untreated A375 tumors
A Novel RAF Kinase Inhibitor with DFG-Out-Binding Mode: High Efficacy in BRAF-Mutant Tumor Xenograft Models in the Absence of Normal Tissue Hyperproliferation.
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Efficacy of the highly selective focal adhesion kinase inhibitor BI 853520 in adenocarcinoma xenograft models is linked to a mesenchymal tumor phenotype.
Cell line
View SamplesmRNA expression profiling of untreated CDX samples and correlation with sensitivity data derived from treatments with BI 853520.
Efficacy of the highly selective focal adhesion kinase inhibitor BI 853520 in adenocarcinoma xenograft models is linked to a mesenchymal tumor phenotype.
Cell line
View SamplesMessenger RNA levels in eukaryotes are balanced by two consecutive regulatory layers. Primary, transcriptional regulation at the level of chromatin and secondary, post-transcriptional regulation of the initial transcript in the cytoplasm. Each layer is individually studied in mechanistic detail, while integration of both processes is required to quantify the individual contribution to steady-state RNA levels. Here we show that chromatin features are sufficient to model transcription rate but with different sensitivities in dividing versus post mitotic cells. In both cases chromatin derived transcript levels explains over 80% of variance in measured RNA level enabling to separate transcription from different post-transcriptional processes. By further inclusion of measurements of mRNA half-life and micro RNA expression data we identify a low quantitative contribution of RNA decay by either micro RNA or general differential turnover to final mRNA levels. Together this establishes a chromatin based quantitative model for the contribution of transcriptional and posttranscriptional processes to steady-state levels of messenger RNA.
Chromatin measurements reveal contributions of synthesis and decay to steady-state mRNA levels.
Specimen part, Disease, Treatment, Time
View SamplesThe differentiated state of somatic cells provides barriers for the efficient derivation of induced pluripotent stem cells (iPSCs). To address why some cell types reprogram more readily than others, we studied the effect of combined modulation of cellular signaling pathways. This revealed that inhibition of TGF together with activation of Wnt signaling in presence of ascorbic acid allows >80% of murine fibroblasts to acquire pluripotency after one week of reprogramming factor expression. In contrast, hepatic progenitors and blood progenitors predominantly required only TGF inhibition or canonical Wnt activation, respectively, to reprogram at efficiencies approaching 100%. Strikingly, blood progenitors reactivated endogenous pluripotency loci in a highly synchronous manner. We further demonstrate that expression of specific chromatin-modifying enzymes and reduced TGF/MAP kinase activity are intrinsic properties associated with the unique reprogramming response of these cells. Together, our observations define novel cell type-specific requirements for the rapid and synchronous reprogramming of somatic cells.
Combinatorial modulation of signaling pathways reveals cell-type-specific requirements for highly efficient and synchronous iPSC reprogramming.
Specimen part, Time
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Aberrant silencing of imprinted genes on chromosome 12qF1 in mouse induced pluripotent stem cells.
Specimen part
View SamplesInduced pluripotent stem cells (iPSCs) can be generated by enforced expression of defined transcription factors in somatic cells. It remains controversial whether iPSCs are equivalent to blastocyst-derived embryonic stem cells (ESCs). Using genetically matched cells, we found that the overall mRNA expression patterns of these cell types are indistinguishable with the exception of a few transcripts encoded on chromosome 12qF1.
Aberrant silencing of imprinted genes on chromosome 12qF1 in mouse induced pluripotent stem cells.
Specimen part
View SamplesHerein, we demonstrated that the cell lineage commitment is unexpectedly regulated by the novel functions of H2A.X, a histone variant which was only well-known for its role in genome integrity maintenance previously. Surprisingly, only in ESCs but not differentiated cells, H2A.X is specifically targeted to genomic regions encoding early embryonic and extra-embryonic lineage genes to repress their expression. In addition, H2A.X is also enriched at genomic regions sensitive to replication stress and maintains genomic stability thereat. Most interestingly, faithful H2A.X deposition plays critical roles in maintaining both cell lineage commitment and genome integrity in iPSC. In iPSC lines which support the development of "all-iPS" animals, H2A.X deposition faithfully recapitulates the ESC pattern and therefore, the genome stability and cell lineage commitment are maintained. In iPSC lines that fail to support embryonic development, defective H2A.X depositions result in aberrant upregulation of early embryonic and extra-embryonic lineage genes and H2A.X-dependent genome instability. Overall design: mRNA-Seq of WT ESC and H2A.X KO ESC; and 4N+, 4N- iPSC.
Histone variant H2A.X deposition pattern serves as a functional epigenetic mark for distinguishing the developmental potentials of iPSCs.
Specimen part, Subject
View SamplesPluripotent cells can be derived from somatic cells by either overexpression of defined transcription factors (resulting in induced pluripotent stem cells (iPSCs)) or by nuclear transfer or cloning (resulting in NT-ESCs). To determine whether cloning further reprograms iPSCs, we used iPSCs as donor cells in nuclear transfer experiments.
Aberrant silencing of imprinted genes on chromosome 12qF1 in mouse induced pluripotent stem cells.
Specimen part
View SamplesIn this experiment, we sought to determine how PRDM14 and CBFA2T2 regulate the transcriptome of mouse embryonic stem cells Overall design: 3 KO mESC lines with 3 biological replicates for each (wild type (3), PRDM14-KO (3), CBFA2T2 (3))
Co-repressor CBFA2T2 regulates pluripotency and germline development.
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