Project description:It has been gradually established that the vast majority of human tumors are extraordinarily heterogeneous at a genetic level. To accurately recapitulate this complexity, it is now evident that in vivo animal models of cancers will require to recreate not just a handful of simple genetic alterations, but possibly dozens and increasingly intricate. Here, we have combined the RCAS/TVA system with the CRISPR/Cas9 genome editing tools for precise modelling of human tumors. We show that somatic deletion in neural stem cells (NSCs) of a variety of known tumor suppressor genes (Trp53, Cdkn2a and Pten), in combination with the expression of an oncogene driver, leads to high-grade glioma formation. Moreover, by simultaneous delivery of pairs of guide RNAs (gRNAs) we generated different gene fusions, either by chromosomal deletion (Bcan-Ntrk1) or by chromosomal translocation (Myb-Qk), and we show that they have transforming potential in vivo and in vitro. Overall design: Bcan-Ntrk1 tumorspheres, Myb-Qk gRNA transduced NSCs, Ctrl gRNA transduced NSCs, Cdkn2a gRNA PDGFB tumorspheres, Pten gRNA PDGFB tumorspheres, and Trp53 gRNA PDGFB tumorspheres. 2 replicates each.
Project description:The clustered regularly interspaced short palindromic repeat (CRISPR)-associated enzyme Cas9 is an RNA-guided nuclease that has been widely adapted for genome editing in eukaryotic cells. However, the in vivo target specificity of Cas9 is poorly understood and most studies rely on in silico predictions to define the potential off-target editing spectrum. Using chromatin immunoprecipitation followed by sequencing (ChIP-seq), we delineate the genome-wide binding panorama of catalytically inactive Cas9 directed by two different single guide (sg) RNAs targeting the Trp53 locus. Cas9:sgRNA complexes are able to load onto multiple sites with short seed regions adjacent to 5’NGG3’ protospacer adjacent motifs (PAM). Examination of dmCas9 binding sites using two Trp53 targeting sgRNAs in Arf -/- MEF cell line (mouse).
Project description:Loss of Pten in the KrasG12D;Amhr2-Cre mutant mice leads to the transformation of ovarian surface epithelial (OSE) cells and rapid development of low-grade, invasive serous adenocarcinomas. Tumors occur with 100% penetrance and express elevated expression of wild type tumor repressor protein 53 (TRP53). To test the functions of TRP53 in the Pten;Kras (Trp53+) mice, we disrupted the Trp53 gene yielding Pten;Kras(Trp53-) mice. By comparing morphology and gene expression profiles in the Trp53+ and Trp53- OSE cells, we document that wild-type TRP53 acts as a major promoter of OSE cell survival and differentiation: cells lacking Trp53 are transformed yet are less adherent, migratory and invasive and exhibit a gene expression profile more like normal OSE cells. These results provide a new paradigm: wild type TRP53 does not preferentially induce apoptotic or senescent related genes in the Pten;Kras(Trp53+) cancer cells but rather increases genes regulating DNA repair, cell cycle progression and proliferation and decreases putative tumor suppressor genes. However, if TRP53 activity is forced higher by exposure to nutlin-3a (an MDM2 antagonist), TRP53 suppresses DNA repair genes and induces the expression of genes that control cell cycle arrest and apoptosis. Thus, in the Pten;Kras(Trp53+) mutant mouse OSE cells and likely in human TP53+ low grade ovarian cancer cells, wild type TRP53 controls global molecular changes that are dependent on its activation status. These results suggest that activation of TP53 may provide a promising new therapy for managing type I ovarian cancer and other cancers in humans where wild-type TP53 is expressed. A direct comparison of ovarian surface epithelia cells from three different genotype mice
Project description:Background: PTEN loss contributes to the development of many cancers and is associated with both hepatocellular carcinoma and cholangiocarcinoma. The pathogenesis of these malignancies is unclear, but they are speculated to arise from common cellular origins. We explored the influence of secondary effects, like hypoxia signaling, through co-deletion of Pten and Vhl in a murine model.Methods: We used a CreER-linked keratin 18 mouse model to conditionally delete Pten, Vhl or both, evaluating the resultant tumors by histology and gene expression microarray. A cohort of human cholangiocarcinoma samples was evaluated for relationships between HIF-1a expression and clinical outcomes.Results: Both Pten deletion genotypes developed liver tumors, but with differing phenotypes. Pten deletion alone led to large, invasive tumors with widespread hepatosteatosis. Co-deletion of Pten and Vhl resulted in low tumor burden and reduced steatosis. Microarray analysis divided mouse tumors’ respective genotypes by gene expression. This gene expression profile grouped a human tumor cohort according to histologic type with the Pten deletion signature aligning with hepatocellular carcinoma, whereas the Pten; Vhl deletion signature associated with cholangiocarcinomas. In a human cholangiocarcinoma cohort, we observed correlation between HIF-1a expression and overall survival.Conclusions: Pten deletion leads to tumor formation and steatosis in mouse livers. Co-deletion of Vhl and Pten resulted in lower tumor burden with gene expression profiling suggesting a switch from hepatocellular expression features to an expression profile more consistent with cholangiocarinoma. A possible relation between HIF-1a expression and increased overall survival in human cholangiocarcinoma suggests that hypoxia signaling influences tumor phenotype. reference x sample
Project description:A loss of function mutation of the Nematostella vectensis POU4 gene was generated by CRISPR/Cas9. Homozygous mutants lack a cell type that can be identified by light microscopy in live animals. Homozygous mutants were separated from siblings based on this phenotype, this approach had been validated by individual genotyping.
Project description:Effect of LUBEL catalytic dead mutation upon Heastshock Overall design: Mutation was introduced in CG11321 catalytic region by CRISPR/Cas9 techonology in Drosophila melanogaster and transcriptome was compared in untreated and heatshocked samples