Densely ionizing radiation is a major component of the space radiation environment and has potentially greater carcinogenic effect compared to sparsely ionizing radiation that is prevalent in the terrestrial environment. It is unknown to what extent the irradiated microenvironment contributes to the differential carcinogenic potential of densely ionizing radiation. To address this gap, 10-week old BALB/c mice were irradiated with 100 cGy sparsely ionizing g-radiation or 10, 30, or 80 cGy of densely ionizing, 350 MeV/amu Si particles and transplanted 3 days later with syngeneic Trp53 null mammary fragments. Tumor appearance was monitored for 600 days. Tumors arising in Si-particle irradiated mice had a shorter median time to appearance, grew faster and were more likely to metastasize. Most tumors arising in sham-irradiated mice were ER-positive, pseudo-glandular and contained both basal keratin 14 and luminal keratin 8/18 cells (designated K14/18), while most tumors arising in irradiated hosts were K8/18 positive (designated K18) and ER negative. Comparison of K18 vs K14/18 tumor expression profiles showed that genes increased in K18 tumors were associated with ERBB2 and KRAS while decreased genes overlapped with those down regulated in metastasis and by loss of E-cadherin. Consistent with this, K18 tumors grew faster than K14/18 tumors and more mice with K18 tumors developed lung metastases compared to mice with K14/18 tumors. However, K18 tumors arising in Si-particle irradiated mice grew even faster and were more metastatic compared to control mice. A K18 Si-irradiated host profile was enriched in genes involved in mammary stem cells, stroma, and Notch signaling. Thus systemic responses to densely ionizing radiation enriches for a ER-negative, K18-positive tumor, whose biology is more aggressive compared to similar tumors arising in non-irradiated hosts.
Densely ionizing radiation acts via the microenvironment to promote aggressive Trp53-null mammary carcinomas.
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View SamplesTransforming growth factor beta-1 (TGFbeta) is a tumor suppressor during the initial stage of tumorigenesis, but it can switch to a tumor promoter during neoplastic progression. Ionizing radiation (IR), both a carcinogen and a therapeutic agent, induces TGFbeta activation in vivo. We now show that IR sensitizes human mammary epithelial cells (HMEC) to undergo TGFbeta-mediated epithelial to mesenchymal transition (EMT). Non-malignant HMEC (MCF10A, HMT3522 S1 and 184v) were irradiated with 2 Gy shortly after attachment in monolayer culture, or treated with a low concentration of TGFbeta (0.4 ng/ml), or double-treated. All double-treated (IR+TGFbeta) HMEC underwent a morphological shift from cuboidal to spindle-shaped. This phenotype was accompanied by decreased expression of epithelial markers E-cadherin, beta-catenin and ZO-1, remodeling of the actin cytoskeleton, and increased expression of mesenchymal markers N-cadherin, fibronectin and vimentin. Furthermore, double-treatment increased cell motility, promoted invasion and disrupted acinar morphogenesis of cells subsequently plated in Matrigel. Neither radiation nor TGFbeta alone elicited EMT, even though IR increased chronic TGFbeta signaling and activity. Gene expression profiling revealed that double treated cells exhibit a specific 10-gene signature associated with Erk/MAPK signaling. We hypothesized that IR-induced MAPK activation primes non-malignant HMEC to undergo TGFbeta-mediated EMT. Consistent with this, Erk phosphorylation were transiently induced by irradiation, persisted in irradiated cells treated with TGFbeta, and treatment with U0126, a Mek inhibitor, blocked the EMT phenotype. Together, these data demonstrate that the interactions between radiation-induced signaling pathways elicit heritable phenotypes that could contribute to neoplastic progression.
Ionizing radiation predisposes nonmalignant human mammary epithelial cells to undergo transforming growth factor beta induced epithelial to mesenchymal transition.
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View SamplesTranscriptional profiling of mammary tissue irradiated at 10 weeks of age with either 100 cGy sparsely ionizing gamma-rays, or 10 cGy or 30 cGy densely ionizing radiation (350 MeV/amu Si). Mammary tissue was collected 1 weeks, 4 weeks, and 12 weeks post-irradiation.
Irradiation of juvenile, but not adult, mammary gland increases stem cell self-renewal and estrogen receptor negative tumors.
Sex, Specimen part, Time
View SamplesDifferent inbred strains of rats differ in their susceptibility to OIR, an animal model of human retinopathy of prematurity. We examined gene expression profiles in Fischer 344 (F344, resistant to OIR) and Sprague Dawley (SD, susceptible to OIR) rats at the early time point of day 3 to identifying gene pathways related to the underlying genetic cause of phenotypic differences between strains.
Gene expression microarray analysis of early oxygen-induced retinopathy in the rat.
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Combinatorial Smad2/3 Activities Downstream of Nodal Signaling Maintain Embryonic/Extra-Embryonic Cell Identities during Lineage Priming.
Specimen part
View SamplesEpiblast cells in the early post-implantation stage mammalian embryo undergo a transition described as lineage priming before cell fate allocation, but signaling pathways acting upstream remain ill defined. Genetic studies demonstrate that Smad2/3 double-mutant mouse embryos die shortly after implantation. To learn more about the molecular disturbances underlying this abrupt failure, here we characterised Smad2/3-deificient embryonic stem cells (ESCs). We found that Smad2/3 double-knockout ESCs induced to form epiblast-like cells (EpiLCs) display changes in nave and primed pluripotency marker gene expression, associated with the disruption of Oct4-bound distal regulatory element. In the absence of Smad2/3, we observed enhanced Bmp target gene expression and de-repression of extra-embryonic gene expression. Cell fate allocation into all three embryonic germ lakers is disrupted. Collectively, these experiments demonstrate that combinatorial Smad2/3 functional activities are required to maintain distinct embryonic and/or extra-embryonic cell identity during lineage priming in the epiblast before gastrulation.
Combinatorial Smad2/3 Activities Downstream of Nodal Signaling Maintain Embryonic/Extra-Embryonic Cell Identities during Lineage Priming.
Specimen part
View SamplesRemoval of the transcription factor SAP1a member of the Ternary Complex Factor (TCF) group of transcription factors which in conjunction with Serum Response Factor (SRF) has been shown to have a profound effect on positive selection in the thymus. When another TCF Elk1 is knocked out in mice there is no effect on positive selection unless it is on a Sap1a KO background where the phenotype is very severe. We have stimulated isolated double positive T cells (DPs) with anti-CD3 to mimic positive selection and compared basal and stimulated transcription across the four genotypes to discover the downstream targets of Sap1a involved in positive selection.
Ternary complex factors SAP-1 and Elk-1, but not net, are functionally equivalent in thymocyte development.
Sex, Age, Specimen part, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Lhx1 functions together with Otx2, Foxa2, and Ldb1 to govern anterior mesendoderm, node, and midline development.
Specimen part
View SamplesExpression profiling of wild-type and Lhx1 null mouse definitive endoderm cultures using Illumina whole genome mouse V2 arrays.
Lhx1 functions together with Otx2, Foxa2, and Ldb1 to govern anterior mesendoderm, node, and midline development.
Specimen part
View SamplesChemokine signaling is important for the seeding of different sites by hematopoietic stem cells during development. Serum Response Factor (SRF) controls multiple genes governing adhesion and migration, mainly by recruiting members of the Myocardin-Related Transcription Factor (MRTF) family of G-actin regulated cofactors. We used vav-iCre to inactivate MRTF-SRF signaling early during hematopoietic development. In both Srf- and Mrtf-deleted animals, hematopoiesis in fetal liver and spleen is intact, but does not become established in fetal bone marrow. Srf-null HSC/Ps (hematopoietic stem/progenitor cells) fail to effectively engraft in transplantation experiments, exhibiting normal proximal signaling responses to SDF-1, but reduced adhesiveness, F-actin assembly, and reduced motility. Srf-null HSC/Ps fail to polarise in response to SDF-1, and cannot migrate through restrictive membrane pores to SDF-1 or Scf in vitro. Mrtf-null HSC/Ps were also defective in chemotactic responses to SDF-1. MRTF-SRF signaling is thus critical for the response to chemokine signaling during hematopoietic development. Overall design: Strand specific RNA sequencing (RNA-seq) in sorted WT and SRF deleted LSK cells with or without a 30 minute SDF stimulation and validation by qRT-PCR
MRTF-SRF signaling is required for seeding of HSC/Ps in bone marrow during development.
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