Previous studies have revealed that UV-stimulation of a variety of cells leads to activation of the EGF receptor, induction of Egr1, growth inhibition and apoptosis. On the other hand both Egr1 and EGF receptor activation are implicated in promoting the progression of prostate cancer. We treated M12 tumorigenic prostate epithelial cells which express little Egr1 with UV irradiation which rapidly activated the EGF receptor and elevated Egr1. Treatment with specific EGFR and ERKI/II inhibitors (PD153035 and UO126, respectively) confirmed that the upregulation of Egr1 was downstream of EGFR and ERKI/II Map kinase pathway. ChIP on chip experiments using Egr1 antibody identified 288 significantly bound promoters upon UV stimulation. Of these target genes, 40% had consensus Egr1 site in their promoters, considerably greater than that expected by chance (p < 0.005). The array binding results were validated by PCR analysis of 25 genes using DNA from conventional IP experiment. Affymetrix gene expression analysis of UV treated and control cells confirmed that a significant number of these bound promoters showed gene expression changes. Addition of siRNA to Egr1 confirmed that the gene expression changes were dependent upon Egr1 expression. Addition of EGF led to similar expression changes for nine tested genes. Proliferation and apoptosis assays confirmed that M12 cells undergo growth arrest and apoptosis following UV irradiation. Moreover, addition of EGF also promoted significant growth inhibition. These results indicate the M12 cells undergo a EGF receptor dependent apoptosis response upon UV-stimulation and that Egr1 mediates the regulation of numerous genes downstream of the EGF receptor that are associated with this response.
Egr1 regulates the coordinated expression of numerous EGF receptor target genes as identified by ChIP-on-chip.
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View SamplesAs rats do not develop neuropathic pain like hypersensitivity as neonates post nerve injury but do as adults we have used these arrays to help define the processes involved in this process.
T-cell infiltration and signaling in the adult dorsal spinal cord is a major contributor to neuropathic pain-like hypersensitivity.
Specimen part, Treatment
View SamplesSialic acids on vertebrate cell surfaces mediate many biological roles. Altered expression of certain sialic acid types or their linkages can have prognostic significance in human cancer. A classic but unexplained example is enhanced 2-6-sialylation on N-glycans, resulting from over-expression of the Golgi enzyme -galactoside:2-6-sialyltransferase (ST6Gal-I). Previous data supporting a role for the resulting Sia2-3Gal1-4GlcNAc (Sia6LacNAc) structure in tumor biology were based on in vitro studies in transfected carcinoma cells, in which increased Sia6LacNAc on 1-integrins enhanced their binding to ligands, and stimulated cell motility. Here we examine for the first time the in vivo role of the ST6Gal-I enzyme in the growth and differentiation of spontaneous mammary cancers in mice transgenic for an MMTV-promoter-driven polyoma-middle-T antigen, a tumor in which beta1-integrin function is important for tumorigenesis, and in maintaining the proliferative state of tumor cells. Tumors induced in St6gal1 null animals were more differentiated in comparison to those in the wild-type background, both by histological analysis and by protein expression profiles. Furthermore, we show the St6gal1 null tumors have selectively altered expression of genes associated with focal adhesion signaling, and have decreased phosphorylation of FAK, a downstream target of 1-integrins. This first in vivo evidence for a role of ST6Gal-I in tumor progression was confirmed using a novel approach, which conditionally restored St6gal1 in cell lines derived from the null tumors. These findings indicate a role for ST6Gal-I as a mediator of tumor progression, with its expression causing a less differentiated phenotype, via enhanced 1-integrin function.
alpha 2-6-Linked sialic acids on N-glycans modulate carcinoma differentiation in vivo.
Sex, Age, Specimen part
View SamplesCancer is a disease of both genetic and epigenetic changes. While increasing evidence demonstrates that oncogenic progression entails chromatin-mediated changes such as DNA methylation, the role of histone variants in cancer initiation and progression currently remains unexplored. Here, we report that the histone variant macroH2A (mH2A) suppresses tumour progression of malignant melanoma.
The histone variant macroH2A suppresses melanoma progression through regulation of CDK8.
Specimen part, Disease
View SamplesAnopheles gambiae mosquitoes play an important role in malaria transmission. In sub-Saharan Africa, the dry season can last several months. The mechanisms for mosquito population to survive through the dry season are poorly understood. One possible mechanism is that adults increase their desiccation tolerance over the dry season. Genetic analyses have shown that inversions 2La, 2Rb, 2Rc, 2Rd and 2Ru are associated with aridity resistance, however little is known about the transcriptional response of genes in response to desiccation.
Genome-wide transcriptional analysis of genes associated with acute desiccation stress in Anopheles gambiae.
Specimen part
View SamplesBackground: Central nervous system (CNS) metastases represent a major problem in the treatment of HER2-positive breast cancer due to the disappointing efficacy of HER2-targeted therapies in the brain microenvironment. The antibody-drug conjugate ado-trastuzumab emtansine (T-DM1) has shown efficacy in trastuzumab-resistant systemic breast cancer. Here, we tested the hypothesis that T-DM1 could overcome trastuzumab resistance in preclinical models of brain metastases.
Preclinical Efficacy of Ado-trastuzumab Emtansine in the Brain Microenvironment.
Specimen part, Disease, Time
View SamplesDepletion of essential nutrients triggers regulatory programs that prolong cell growth and survival. Starvation-induced processes increase nutrient transport, mobilize nutrient storage, and recycle nutrients between cellular components. This leads to an effective increase in intracellular nutrients, which may act as a negative feedback that down-regulates the starvation program. To examine how cells overcome this potential instability, we followed the transcription response of budding yeast transferred to medium lacking phosphate. Genes were induced in two temporal waves. The first wave was stably maintained and persisted even upon phosphate replenishment, indicating a positive feedback loop. This commitment was abolished after two hours with the induction of the second expression wave, coinciding with the reduction in cell growth rate. We identify genes that mediate this loss of commitment, and show that the overall temporal stability of the expression response depends on the sequential pattern of gene induction. Our results emphasize the key role of gene expression dynamics in optimizing cellular adaptation. Wild type cells were grown at high Phosphate medium, washed and transferred to no phosphate medium. Sample were taken every 15 minuets for 6 hours Overall design: 25 samples were taken during the time course. Expression data was normalized to the first time point (cells grown at high phosphate medium)
Sequential feedback induction stabilizes the phosphate starvation response in budding yeast.
Subject
View SamplesDepletion of essential nutrients triggers regulatory programs that prolong cell growth and survival. Starvation-induced processes increase nutrient transport, mobilize nutrient storage, and recycle nutrients between cellular components. This leads to an effective increase in intracellular nutrients, which may act as a negative feedback that down-regulates the starvation program. To examine how cells overcome this potential instability, we followed the transcription response of budding yeast transferred to medium lacking phosphate. Genes were induced in two temporal waves. The first wave was stably maintained and persisted even upon phosphate replenishment, indicating a positive feedback loop. This commitment was abolished after two hours with the induction of the second expression wave, coinciding with the reduction in cell growth rate. We identify genes that mediate this loss of commitment, and show that the overall temporal stability of the expression response depends on the sequential pattern of gene induction. Our results emphasize the key role of gene expression dynamics in optimizing cellular adaptation. ?phm3 cells were grown at high Phosphate medium, washed and transferred to no phosphate medium. Sample were taken every 15 minuets for 6 hours Overall design: 25 samples were taken during the time course. Expression data was normalized to the first time point (cells grown at high phosphate medium)
Sequential feedback induction stabilizes the phosphate starvation response in budding yeast.
Subject
View SamplesDepletion of essential nutrients triggers regulatory programs that prolong cell growth and survival. Starvation-induced processes increase nutrient transport, mobilize nutrient storage, and recycle nutrients between cellular components. This leads to an effective increase in intracellular nutrients, which may act as a negative feedback that down-regulates the starvation program. To examine how cells overcome this potential instability, we followed the transcription response of budding yeast transferred to medium lacking phosphate. Genes were induced in two temporal waves. The first wave was stably maintained and persisted even upon phosphate replenishment, indicating a positive feedback loop. This commitment was abolished after two hours with the induction of the second expression wave, coinciding with the reduction in cell growth rate. We identify genes that mediate this loss of commitment, and show that the overall temporal stability of the expression response depends on the sequential pattern of gene induction. Our results emphasize the key role of gene expression dynamics in optimizing cellular adaptation. pho90_OX cells were grown at high Phosphate medium, washed and transferred to no phosphate medium. Sample were taken every 15 minuets for 6 hours Overall design: 25 samples were taken during the time course. Expression data was normalized to the first time point (cells grown at high phosphate medium)
Sequential feedback induction stabilizes the phosphate starvation response in budding yeast.
Subject
View SamplesDepletion of essential nutrients triggers regulatory programs that prolong cell growth and survival. Starvation-induced processes increase nutrient transport, mobilize nutrient storage, and recycle nutrients between cellular components. This leads to an effective increase in intracellular nutrients, which may act as a negative feedback that down-regulates the starvation program. To examine how cells overcome this potential instability, we followed the transcription response of budding yeast transferred to medium lacking phosphate. Genes were induced in two temporal waves. The first wave was stably maintained and persisted even upon phosphate replenishment, indicating a positive feedback loop. This commitment was abolished after two hours with the induction of the second expression wave, coinciding with the reduction in cell growth rate. We identify genes that mediate this loss of commitment, and show that the overall temporal stability of the expression response depends on the sequential pattern of gene induction. Our results emphasize the key role of gene expression dynamics in optimizing cellular adaptation. phm3 damp cells were grown at high Phosphate medium, washed and transferred to no phosphate medium. Sample were taken every 15 minuets for 6 hours Overall design: 25 samples were taken during the time course. Expression data was normalized to the first time point (cells grown at high phosphate medium)
Sequential feedback induction stabilizes the phosphate starvation response in budding yeast.
Subject
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