Dysregulated Wnt signalling is seen in approximately 30% of hepatocellular cancers, thus finding pathways downstream of activation of Wnt signalling is key. Using cre lox technology we have deleted the the adenomatous polyposis coli tumour suppressor protein (Apc) within the adult mouse liver and observed a rapid increase in nuclear beta-catenin and C-Myc. This is associated with an induction of proliferation leading to hepatomegally within 4 days of gene deletion. To investigate the downstream pathways responsible for these phenotypes we analysed the impact of inactivating Apc in the context of deficiency of the potentially key effectors beta-catenin and c-Myc. beta-catenin loss rescues both the proliferation and hepatomegally phenotypes following Apc loss. However c-Myc deletion, which rescues the phenotypes of Apc loss in the intestine, had no effect on the phenotypes of Apc loss. The consequences of deregulation the Wnt pathway within the liver are therefore strikingly different to those observed within the intestine, with the vast majority of Wnt targets beta-catenin dependent but c-Myc independent in the liver.
B-catenin deficiency, but not Myc deletion, suppresses the immediate phenotypes of APC loss in the liver.
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View SamplesEphB receptors regulate the proliferation and positioning of intestinal stem and progenitor cells. In addition, they can act as tumor promoters for adenoma development, but suppress progression to invasive carcinoma. Here we used imatinib to abrogate Abl kinase activity in ApcMin/+ mice and in mice with LGR5+ stem cells genetically targeted for APC. This treatment inhibited the tumor-promoting effects of EphB signaling without attenuating EphB-mediated tumor suppression, demonstrating the role of EphB signaling in intestinal tumor initiation. The investigated treatment regimen extended the lifespan of ApcMin/+ mice, and reduced cell proliferation in cultured slices of adenomas from FAP patients. These findings connect the EphB signaling pathway to the regulation of intestinal adenoma initiation via Abl kinase. Our findings may have clinical implications for pharmacological therapy against adenoma formation and cancer progression in patients predisposed to develop colon cancer.
An EphB-Abl signaling pathway is associated with intestinal tumor initiation and growth.
Specimen part
View SamplesPurpose: To determine global gene expression changes following siRNA knockdown of Myc, Kcnk1, and Snta1 compared to non-targeting siRNAs or mock-transfected cells Methods: Total RNA was processed using the Illumina TruSeq Stranded mRNA Sample Preparation Kit according to manufacturer's protocol. Generated cDNA libraries were sequenced using an Illumina HiSeq 2000 sequencer with four biological replicates sequenced per condition using single read, 50 cycle runs. Quality of sequencing reads were assessed using FastQC (Babraham Bioinformatics) and then aligned to a reference genome (hg19, UCSC Genome Browser) using TopHat. Sequencing yielded, on average, 23.7 million unique reads per sample with a 60.7 - 65.7% mapping rate. Cufflinks was used to generate transcript abundance for each annotated protein-coding gene as Fragments Per Kilobase of transcript per Million mapped reads (FPKM), and statistical analysis and comparison of FPKM values was calculated using R (Bioconductor). Results: Fold changes comparing mock and a non-targeting siRNA were highly congruent. Myc RNAi induced numerous changes, with 955 downregulated genes and 1214 upregulated genes. The effect on Myc itself was relatively modest, possibly reflecting its ability to negatively auto-regulate its own expression. Gene ontology analysis highlighted ribosome biogenesis, metabolism, gene expression, cell cycle, and apoptosis pathways, consistent with known Myc functions. The Kcnk1 siRNA affected 424 genes, with KCNK1 itself one of the most repressed. While gene ontology analysis also highlighted metabolism and biosynthesis pathways, the p-values and fold enrichment scores were substantially lower, indicating that DiM can be suppressed without major effects on metabolism and biosynthesis pathways. The Snta1 siRNA deregulated 575 genes, with SNTA1 itself the most repressed gene. Cell cycle and mitosis-related gene ontology terms feature heavily, consistent with this siRNA accelerating mitotic exit. Interestingly, FoxM1, which drives G2/M gene expression was reduced 1.75-fold, indicating that this siRNA may disrupt mitotic controls by deregulating FoxM1. Conclusions: Global gene expression profiling identifies Egr1 as regulator of mitotic cell fate. Overall design: Total RNA was extracted from at least four replicates of siRNA-transfected cells and libraries for sequencing was prepared for each replicate.
MYC Is a Major Determinant of Mitotic Cell Fate.
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View SamplesRecent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells and tumour initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-kB pathway can drive dedifferentiation of intestinal cells lacking Apc.
TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis.
Specimen part
View SamplesRecent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells and tumour initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-kB pathway can drive dedifferentiation of intestinal cells lacking Apc.
TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis.
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View SamplesIn order to establish a list of candidate direct COUP-TFI gene targets in the inner ear, we analyzed the differential gene expression profiles of the wild-type and the COUP-TFI/ P0 inner ears.
Genome-wide analysis of binding sites and direct target genes of the orphan nuclear receptor NR2F1/COUP-TFI.
Specimen part
View SamplesLiver injury results in rapid regeneration through hepatocyte proliferation and hypertrophy. However, after acute severe injury, such as acetaminophen poisoning, effective regeneration may fail. We investigated how senescence underlies this regenerative failure. In human acute liver disease, and murine models, p21-dependent hepatocellular senescence was proportionate to disease severity and was associated with impaired regeneration. In an acetaminophen injury model a transcriptional signature associated with the induction of paracrine senescence is observed within twenty four hours, and is followed by one of impaired proliferation. In genetic models of hepatocyte injury and senescence we observed transmission of senescence to local uninjured hepatocytes. Spread of senescence depended upon macrophage derived TGFß1 ligand. In acetaminophen poisoning inhibition of TGFß receptor 1 (TGFßR1) improved survival. TGFßR1 inhibition reduced senescence and enhanced liver regeneration even when delivered after the current therapeutic window. This mechanism, in which injury induced senescence impairs regeneration, is an attractive therapeutic target for acute liver failure. Overall design: RNA-seq analysis was performed on a total of 24 samples extracted from murine liver, post hepatic injury induced by acetaminophen administration. Transcriptional profiles were from replicate samples generated at defined timepoints - 12, 24, 36, 48 and 72 hours post injury. Replicate samples were generated from 4 individual animals sacrificed at each timepoint, and compared to a control cohort of 4 animals not subjected to acetaminophen treatment.
TGFβ inhibition restores a regenerative response in acute liver injury by suppressing paracrine senescence.
Specimen part, Cell line, Subject, Time
View SamplesWe profile gene expression changes in two mutant strains lacking the D. melanogaster HP1 homolog HP1B at the third instar larval stage. Compared to the yw control strain, several hundred genes are deregulated, with metabolic genes being over-represented among the deregulated gene set. Overall design: Examination of gene expression in two genotypes
HP1B is a euchromatic Drosophila HP1 homolog with links to metabolism.
Specimen part, Cell line, Subject
View SamplesRefined cancer models are required to assess the burgeoning number of potential targets for cancer therapeutics within a rapid and clinically relevant context. Here we utilize tumor-associated genetic pathways to transform primary human epithelial cells from epidermis, oropharynx, esophagus, and cervix into genetically defined tumors within an entirely human 3-dimensional (3-D) tissue environment incorporating cell-populated stroma and intact basement membrane (BM). These engineered organotypic tissues recapitulated natural features of tumor progression, including epithelial invasion through the BM, a complex process critically required for biologic malignancy in 90% of human cancers. Invasion was rapid, and potentiated by stromal cells. Oncogenic signals in 3-D tissue, but not 2-D culture, resembled gene expression profiles from spontaneous human cancers. Screening well-characterized signaling pathway inhibitors in 3-D organotypic neoplasia helped distil a clinically faithful cancer gene signature. Multi-tissue 3-D human tissue cancer models may provide an efficient and relevant complement to current approaches to characterize cancer progression.
Invasive three-dimensional organotypic neoplasia from multiple normal human epithelia.
No sample metadata fields
View SamplesRefined cancer models are required to assess the burgeoning number of potential targets for cancer therapeutics within a rapid and clinically relevant context. Here we utilize tumor-associated genetic pathways to transform primary human epithelial cells from epidermis, oropharynx, esophagus, and cervix into genetically defined tumors within an entirely human 3-dimensional (3-D) tissue environment incorporating cell-populated stroma and intact basement membrane (BM). These engineered organotypic tissues recapitulated natural features of tumor progression, including epithelial invasion through the BM, a complex process critically required for biologic malignancy in 90% of human cancers. Invasion was rapid, and potentiated by stromal cells. Oncogenic signals in 3-D tissue, but not 2-D culture, resembled gene expression profiles from spontaneous human cancers. Screening well-characterized signaling pathway inhibitors in 3-D organotypic neoplasia helped distil a clinically faithful cancer gene signature. Multi-tissue 3-D human tissue cancer models may provide an efficient and relevant complement to current approaches to characterize cancer progression.
Invasive three-dimensional organotypic neoplasia from multiple normal human epithelia.
Specimen part
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