We are examining the genes that control initiation and progression of murine medulloblastomas that result from loss of patched. Approximately 25% of human medulloblastomas have mutations in patched or in other elements of the sonic hedgehog pathway. However, the cells from which these tumors originate (neural progenitors or stem cells), the cells that are responsible for tumor propagation (cancer stem cells), and the genes that are required for tumor progression are poorly understood. To address these questions, we have developed conditional patched knockout mice in which the gene is deleted in neural stem cells or progenitors. In addition, we have isolated a population of tumor-propagating cells from these tumors. By studying these models we will gain insight into the mechanisms of tumorigenesis and identify new targets for therapy.
Identification of CD15 as a marker for tumor-propagating cells in a mouse model of medulloblastoma.
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View SamplesGene expression profiles were collected from HEK-HT cells expressing H-Ras with Ras-activating (G12V), Raf-activating (G12V,T35S), RalGEF-activating (G12V,E37G), or PI3K-activating (G12V,Y40C) mutations.
A genomic strategy to elucidate modules of oncogenic pathway signaling networks.
Specimen part
View SamplesDespite advances in contemporary chemotherapeutic strategies, long term survival still remains elusive for patients with metastatic colorectal cancer. A better understanding of the molecular markers of drug sensitivity to match therapy with patient is needed to improve clinical outcomes. In this study, we used in vitro drug sensitivity data from the NCI-60 cell lines together with their Affymetrix microarray data to develop a gene expression signature to predict sensitivity to oxaliplatin. In order to validate our oxaliplatin sensitivity signature, Patient-Derived Colorectal Cancer Explants (PDCCEs) were developed in NOD-SCID mice from resected human colorectal tumors. Analysis of gene expression profiles found similarities between the PDCCEs and their parental human tumors, suggesting their utility to study drug sensitivity in vivo. The oxaliplatin sensitivity signature was then validated in vivo with response data from 14 PDCCEs treated with oxaliplatin and was found to have an accuracy of 92.9% (Sensitivity=87.5%; Specificity=100%). Our findings suggest that PDCCEs can be a novel source to study drug sensitivity in colorectal cancer. Furthermore, genomic-based analysis has the potential to be incorporated into future strategies to optimize individual therapy for patients with metastatic colorectal cancer.
Characterization of an oxaliplatin sensitivity predictor in a preclinical murine model of colorectal cancer.
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View SamplesTransgenic (Probasin driven Myr-AKT)or wild-type littermates were treated with RAD001 or placebo and sacrificed at 12 and 48 hours following the beginning of treatment
mTOR inhibition reverses Akt-dependent prostate intraepithelial neoplasia through regulation of apoptotic and HIF-1-dependent pathways.
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View SamplesProstate tumors are among the most heterogeneous of cancers, both histologically and clinically. Microarray expression analysis was used to determine whether global biological differences underlie common pathological features of prostate cancer and to identify genes that might anticipate the clinical behavior of this disease. While no expression correlates of age, serum prostate specific antigen (PSA), and measures of local invasion were found, a set of genes was identified that strongly correlated with the state of tumor differentiation as measured by Gleason score. Moreover, a model using gene expression data alone accurately predicted patient outcome following prostatectomy. These results support the notion that the clinical behavior of prostate cancer is linked to underlying gene expression differences that are detectable at the time of diagnosis.
Gene expression correlates of clinical prostate cancer behavior.
Specimen part
View SamplesWe sequenced liver biopsy tissue from healthy, patients with NAFLD and patients with NASH Overall design: 3 patients either healthy, presenting with NAFLD or NASH
Preclinical Models for Studying NASH-Driven HCC: How Useful Are They?
Sex, Age, Subject
View SamplesWe have generated transgenic mice expressing constitutively activated aryl hydrocarbon receptor (CA-AhR) to examine the biological consequences of AhR activation..
A novel role for the dioxin receptor in fatty acid metabolism and hepatic steatosis.
Specimen part
View SamplesMedulloblastoma (MB) is the most common malignant brain tumor in children. Patients whose tumors exhibit overexpression or amplification of the MYC oncogene (c-MYC) usually have an extremely poor prognosis, but there are no animal models of this subtype of the disease. Here we show that cerebellar stem cells expressing Myc and mutant Trp53 (p53) generate aggressive tumors following orthotopic transplantation. These tumors consist of large, pleiomorphic cells and resemble human MYC-driven MB at a molecular level. Notably, antagonists of PI3K/mTOR signaling, but not Hedgehog signaling, inhibit growth of tumor cells. These findings suggest that cerebellar stem cells can give rise to MYC-driven MB, and identify a novel model that can be used to test therapies for this devastating disease.
An animal model of MYC-driven medulloblastoma.
Specimen part
View SamplesGrowth hormone signaling in hepatocytes is fundamentally important. Disruptions in this pathway have led to fatty liver and other metabolic abnormalities. Growth hormone signals through the JAK2/STAT5 pathway. Mice with hepatocyte specific deletion of STAT5 were previously shown to develop fatty liver. Our aim in this study was to determine the effect of deleting JAK2 in hepatocytes on liver gene expression. To do so, we generated animals with hepatocyte specific deletion of JAK2.
Abrogation of growth hormone secretion rescues fatty liver in mice with hepatocyte-specific deletion of JAK2.
Sex, Age, Specimen part
View SamplesDuring chronic stimulation T cells acquire an exhausted phenotype characterized by expression of multiple inhibitory receptors and down-modulation of effector function. While this is required for the protection of the organism from excessive immunopathology, it also prevents successful immunity against persistent viruses or tumor cells. Here we demonstrate that CD8+ T cell exhaustion is characterized by a progressive decline in cellular metabolism. Exhausted T cells exhibit reduced metabolic reserve, impaired fatty acid oxidation and production of mitochondrial reactive oxygen species (ROS). Blockade of inhibitory PD-1/PD-L1 signaling rescued mitochondrial biogenesis, oxidative phosphorylation and ROS production, which was required for efficient restoration of cellular expansion and effector function. Expression of inhibitory receptors and impaired metabolic function was fuled by high amounts of IRF4, BATF and NFAT, which formed a TCR-responsive transcriptional circuit that sustained the transcriptional network responsible for T cell exhaustion. Overall design: Transcriptional profiling of T cells in mice with chronic and acute infections using RNA sequencing
Transcription Factor IRF4 Promotes CD8<sup>+</sup> T Cell Exhaustion and Limits the Development of Memory-like T Cells during Chronic Infection.
Specimen part, Cell line, Subject, Time
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