Medulloblastoma encompasses a collection of clinically and molecularly diverse tumor subtypes that together comprise the most common malignant childhood brain tumor. These tumors are thought to arise within the cerebellum, with approximately 25% originating from granule neuron precursor cells (GNPCs) following aberrant activation of the Sonic Hedgehog pathway (hereafter, SHH-subtype). The pathological processes that drive heterogeneity among the other medulloblastoma subtypes are not known, hindering the development of much needed new therapies. Here, we provide evidence that a discrete subtype of medulloblastoma that contains activating mutations in the WNT pathway effector CTNNB1 (hereafter, WNT-subtype), arises outside the cerebellum from cells of the dorsal brainstem. We found that genes marking human WNT-subtype medulloblastomas are more frequently expressed in the lower rhombic lip (LRL) and embryonic dorsal brainstem than in the upper rhombic lip (URL) and developing cerebellum. Magnetic resonance imaging (MRI) and intra-operative reports showed that human WNT-subtype tumors infiltrate the dorsal brainstem, while SHH-subtype tumors are located within the cerebellar hemispheres. Activating mutations in Ctnnb1 had little impact on progenitor cell populations in the cerebellum, but caused the abnormal accumulation of cells on the embryonic dorsal brainstem that included aberrantly proliferating Zic1+ precursor cells. These lesions persisted in all mutant adult mice and in 15% of cases in which Tp53 was concurrently deleted, progressed to form medulloblastomas that recapitulated the anatomy and gene expression profiles of human WNT-subtype medulloblastoma. We provide the first evidence that subtypes of medulloblastoma have distinct cellular origins. Our data provide an explanation for the marked molecular and clinical differences between SHH and WNT-subtype medulloblastomas and have profound implications for future research and treatment of this important childhood cancer.
Subtypes of medulloblastoma have distinct developmental origins.
Specimen part
View SamplesTobacco use and alcohol consumption are two major contributing factors for head and neck squamous cell carcinoma (HNSCC) carcinogenesis. We combined the 4-nitroquinoline-1-oxide (4-NQO) oral carcinogenesis mouse model and the Meadows-Cook alcohol mouse models and performed next generation genome-wide RNA-sequencing of tongues. We determined changes in transcript levels in four groups: 4-NQO followed by ethanol treatment (4-NQO/EtOH), 4-NQO followed by normal drinking water (4-NQO/Untr.), vehicle control followed by ethanol treatment (V.C./EtOH), and vehicle control followed by normal drinking water (V.C./Untr.). We found that the 494 gene transcripts were significantly changed (at least a 2-fold change where p<0.05) in the V.C./EtOH group compared to the V.C./Untr. group. The 4-NQO/Untr. group had 1,808 transcripts significantly changed compared to the V.C./Untr group, while the 4-NQO/EtOH group had 3,606 significantly changed transcripts as compared to the V.C/Untr. group. This study is the first to show that 4-NQO followed by ethanol cause the largest number of changes in transcript levels in the tongue. Overall design: High-throughput Illumina HiSeq2000 Deep Sequencing results were compared to the mm9 mouse reference genome. Enrichment levels were determined using the Cufflinks software using the unit of fragments per kilobase per million reads (FPKM) model. n=3 for each treatment group.
Identification of Ethanol and 4-Nitroquinoline-1-Oxide Induced Epigenetic and Oxidative Stress Markers During Oral Cavity Carcinogenesis.
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View SamplesIt is possible to identify the key genes and pathways involved in specific physiological processes using transcriptome analyses. However, these powerful new deep sequencing-based methods have rarely been applied to studies of memory function. We used the bow-tie maze to train rats by exposing them to highly familiar objects or to novel objects. Total RNA sequencing was then used to compare the transcriptome of the perirhinal cortices of naïve control rats and rats exposed to novel and familiar stimuli. Differentially expressed genes were identified between group Novel and group Familiar rats and these included genes coding for transcription factors and extracellular matrix-related proteins. Moreover, differences in alternative splicing were also detected between the two groups. To conclude, this study shows that RNA sequencing can be used as a tool to identify differences in gene expression in behaving animals undergoing the same task but encountering different exposures. Overall design: RNA profiles of perirhinal cortex from rats exposed to novel objects (n=5) or familiar objects (n=5) in a recognition memory task were investigated using the Ion Proton System. Controls were naïve rats that had not undergone any behavioural testing (n=4).
Recognition memory-induced gene expression in the perirhinal cortex: A transcriptomic analysis.
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View SamplesThyroid cancer is common, yet the sequence of alterations that promote tumor formation are incompletely understood. Here we describe a novel model of thyroid carcinoma in zebrafish that reveals temporal changes due to BRAFV600E. Through the use of real-time in vivo imaging we observe disruption in thyroid follicle structure that occurs early in thyroid development. Combinatorial treatment using BRAF and MEK inhibitors reversed the developmental effects induced by BRAFV600E. Adult zebrafish expressing BRAFV600E in thyrocytes developed invasive carcinoma. We identified a gene expression signature from zebrafish thyroid cancer that is predictive of disease free survival in patients with papillary thyroid cancer. Gene expression studies nominated TWIST2 as a key effector downstream of BRAF. Using CRISPR/Cas9 to genetically inactivate a TWIST2 orthologue, we suppressed the effects of BRAFV600E and restored thyroid morphology and hormone synthesis. These data suggest that expression of TWIST2 plays a role in an early step of BRAFV600E-mediated transformation. Overall design: 3 embryo tg-TOM (tg:TdTomato), 3 embryo tg-BRAFV600E-TOM, 3 adult tg-TOM and 5 adult tg-BRAFV600E-TOM biological replicates were sequenced. Strains with tg:TdTomato express the TdTomato fluorophore under control of the zebrafish thyroglobulin promoter (tg).
Oncogenic BRAF disrupts thyroid morphogenesis and function via twist expression.
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View SamplesSamples used for hybridization consisted of non-pooled (NP) RNA extracts from 8 groups in each of two time periods after drug administration: oil vehicle treated control embryonic limb bud mesoderm and ectoderm, phosphate buffered saline vehicle control embryonic limb bud mesoderm and ectoderm, acetazolamide treated embryonic limb bud mesoderm and ectoderm, and cadmium sulfate treated embryonic limb bud mesoderm and ectoderm. Forty-eight hybridization experiments were on non-pooled (NP) individual RNA extracts.
Microarray analysis of murine limb bud ectoderm and mesoderm after exposure to cadmium or acetazolamide.
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View SamplesThe goal of this experiment was to examine the innate immune response to helminth infection in the lung. Hookworms (like many other helminths) use an obligate migration pathway through the lung. Their infection has been characterized in the gut in detail, but early immune responses in the lung have not been fully characterized.
Innate immune responses to lung-stage helminth infection induce alternatively activated alveolar macrophages.
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View SamplesProtein deficiency and intestinal parasite infection during pregnancy impair fetal growth through passage of signals from the maternal environment which signal impairment of fetal growth. The placenta is an important regulator of the transfer of these signals through differential expression of key placental genes. We used microarrays to examine placental gene expression responses to maternal protein deficiency (6% vs. 24% protein) and Heligmosomoides bakeri infection.
Expression of growth-related genes in the mouse placenta is influenced by interactions between intestinal nematode (Heligmosomoides bakeri) infection and dietary protein deficiency.
Specimen part
View SamplesThis study was undertaken in order to characterize the functions of Rex-1 and identify potential Rex-1 target genes.Both alleles of the Rex-1 gene were disrupted in J1 mouse embryonic stem cells. Gene expression levels in one of the resulting Rex-1 knockout cell lines was compared to that of J1 wild type cells.
Analysis of Rex1 (zfp42) function in embryonic stem cell differentiation.
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View SamplesTo uncover novel molecules involved in taste detection, we performed a microarray-based screen for genes enriched in taste neurons. Proboscis RNA from flies homozygous for a recessive poxn null mutation was compared to RNA from heterozygous controls. Poxn mutants have a transformation of labellar gustatory chemosensory bristles into mechanosensory bristles and therefore lack most or all taste neurons.
The molecular basis for water taste in Drosophila.
Sex
View SamplesMicroarray expression analysis of mouse ESCs treated with the MYCi 10058-F4.
Myc Depletion Induces a Pluripotent Dormant State Mimicking Diapause.
Specimen part
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