Background. The cAMP Response Element Binding Protein, CREB, is a transcription factor that regulates cell proliferation, differentiation, and survival in several model systems, including neuronal and hematopoietic cells. We demonstrated that CREB is overexpressed in acute myeloid and leukemia cells compared to normal hematopoietic stem cells. CREB knockdown inhibits leukemic cell proliferation in vitro and in vivo, but does not affect long-term hematopoietic reconstitution. Therefore, we propose CREB to be a potential target for therapy. To understand downstream pathways regulating CREB, we performed expression profiling with RNA from the K562 myeloid leukemia cell line.
Expression profile of CREB knockdown in myeloid leukemia cells.
No sample metadata fields
View Sampleslet-7c and miR-294 were transfected into Dgcr8 -/- miRNA deficient ES cells and RNA was harvested after 12 hours
Opposing microRNA families regulate self-renewal in mouse embryonic stem cells.
Specimen part
View SamplesDicer, which is required for the processing of both microRNAs (miRNAs) and small interfering RNAs (siRNAs), is essential for oocyte maturation. Oocytes express both miRNAs and endogenous siRNAs (endo-siRNAs). To determine whether the abnormalities in Dicer knockout oocytes during meiotic maturation are secondary to the loss of endo-siRNAs and/or miRNAs, we deleted Dgcr8, which encodes a RNA binding protein specifically required for miRNA processing. In striking contrast to Dicer, Dgcr8 deficient oocytes matured normally and, when fertilized with wild-type sperm, produced healthy appearing offspring, even though miRNA levels were reduced to similar levels as Dicer deficient oocytes. Furthermore, the deletion of both maternal and zygotic Dgcr8 alleles did not impair preimplantation development including the determination of the inner cell mass (ICM) and trophectoderm. Most surprisingly, the mRNA profiles of wild-type and Dgcr8 null oocytes were essentially identical while Dicer null oocytes showed hundreds of misregulated transcripts. These findings show that miRNA function is globally suppressed during oocyte maturation and preimplantation development and that endo-siRNAs, rather than miRNAs, underlie the Dicer knockout phenotype in oocytes.
Opposing microRNA families regulate self-renewal in mouse embryonic stem cells.
Specimen part
View SamplesIn filamentous strains of S. cerevisiae, nitrogen stress elicits a complex morphogenetic program resulting in the transition to a filamentous form of growth. The transcription factors Flo8p and Mss11p are both required for this filamentous growth transition, in that homozygous diploid flo8(delta/delta) and mss11(delta/delta) strains do not undergo filamentation under conditions of nitrogen stress. To identify genes that are regulated either directly or indirectly by the Flo8p and Mss11p transcription factors, we have implemented DNA microarray analysis to profile changes in mRNA levels in homozygous diploid strains of the filamentous (Sigma)1278b genetic background deleted for FLO8 and MSS11, respectively, under conditions of nitrogen stress. The transcriptional profiles will identify genes with altered transcriptional levels in the deletion mutants, serving as a means to identify cellular processes and signaling pathways regulated by Flo8p and Mss11p function.
TEAK: topology enrichment analysis framework for detecting activated biological subpathways.
No sample metadata fields
View SamplesForkhead BoxO (FoxO) transcription factors expressed in adult skeletal muscle promote muscle atrophy during various catabolic conditions. We have identified the genome wide target genes and biological networks regulated by FoxO in skeletal muscle during Colon-26 (C-26) cancer cachexia.
Genome-wide identification of FoxO-dependent gene networks in skeletal muscle during C26 cancer cachexia.
Specimen part, Disease, Disease stage, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Distinct cachexia profiles in response to human pancreatic tumours in mouse limb and respiratory muscle.
Specimen part, Treatment
View SamplesBackground: Cancer cachexia is a life-threatening metabolic syndrome that causes significant loss of skeletal muscle mass and significantly increases mortality in cancer patients. Currently, there is an urgent need for better understanding of the molecular pathophysiology of this disease, so that effective therapies can be developed. Almost all pre-clinical studies evaluating skeletal muscle’s response to cancer have focused on one or two pre-clinical models, and almost all have focused specifically on limb muscles. In the current study, we reveal key differences in the histology and transcriptomic signatures of a limb muscle and a respiratory muscle in orthotopic pancreatic cancer patient-derived xenograft (PDX) mice. Methods: To create the four cohorts of PDX mice evaluated in this study, tumors resected from four pancreatic ductal adenocarcinoma (PDAC) patients were portioned and attached to the pancreas of immunodeficient NSG mice. Results: Body weight, muscle mass, and fat mass were significantly decreased in each PDX line. Histological assessment of cryosections taken from the tibialis anterior (TA) and diaphragm (DIA) revealed differential effects of tumor-burden on their morphology. Subsequent genome-wide microarray analysis on TA and DIA revealed key differences between their transcriptomes in response to cancer as well. Indeed, upregulated genes in the diaphragm were enriched for extracellular matrix (ECM) protein-encoding genes and genes related to the inflammatory response, and downregulated genes were enriched for mitochondria related protein-encoding genes. Conversely, the TA showed upregulation of canonical atrophy-associated pathways such as ubiquitin-mediated protein degradation and apoptosis and enrichment of downregulated genes encoding ECM proteins. Conclusions: These data suggest that distinct biological processes account for wasting in different skeletal muscles in response to the same tumor burden. Further investigation into these differences will be critical for the future development of effective clinical strategies to counter cancer cachexia.
Distinct cachexia profiles in response to human pancreatic tumours in mouse limb and respiratory muscle.
Specimen part, Treatment
View SamplesGiven the importance of deregulated phosphoinositide (PI) signaling in leukemic hematopoiesis, genes coding for proteins that regulate PI metabolism may have significant and as yet unappreciated roles in leukemia. We performed a targeted knockdown screen of PI modulator genes in human AML cells and identified candidates required to sustain proliferation or prevent apoptosis. One of these, the lipid kinase phosphatidylinositol-5-phosphate 4-kinase, type II, alpha (PIP4K2A) regulates cellular levels of phosphatidylinositol-5-phosphate (PtsIns5P) and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). We found PIP4K2A to be essential for the clonogenic and leukemia-initiating potential of human AML cells, and for the clonogenic potential of murine MLL-AF9 AML cells. Importantly, PIP4K2A is also required for the clonogenic potential of primary human AML cells. Its knockdown results in accumulation of the cyclin-dependent kinase inhibitors CDKN1A and CDKN1B, G1 cell cycle arrest and apoptosis. Both CDKN1A accumulation and apoptosis were partially dependent upon activation of the mTOR pathway. Critically, however, PIP4K2A knockdown in normal hematopoietic stem and progenitor cells, both murine and human, did not adversely impact either clonogenic or multilineage differentiation potential, indicating a selective dependency which we suggest may be the consequence of the regulation of different transcriptional programmes in normal versus malignant cells. Thus, PIP4K2A is a novel candidate therapeutic target in myeloid malignancy.
A targeted knockdown screen of genes coding for phosphoinositide modulators identifies PIP4K2A as required for acute myeloid leukemia cell proliferation and survival.
Specimen part, Time
View SamplesSerum levels of interleukin-8 (IL-8) are increased in the serum of people with pancreatic cancer and associated with the loss of body weight and low muscle mass. We have identified that systemic (intraperitoneal) injection of IL-8 into mice induces significant skeletal muscle atrophy. Transcriptional profiling of muscle harvested from these same mice identified the genes and biological processes associated with this IL-8 induced atrophy including gene clusters related to chromatin modification, muscle cell differentiation, and ubiquitin ligase complex.
IL-8 Released from Human Pancreatic Cancer and Tumor-Associated Stromal Cells Signals through a CXCR2-ERK1/2 Axis to Induce Muscle Atrophy.
Treatment
View Samples40 current smokers and 40 age- and gender- matched never smokers underwent buccal biopsies.The study had four objectives: (a) to define the effects of smoking on the transcriptome of oral epithelial cells; (b) to determine if any of the effects of tobacco smoke on the transcriptome are gender-dependent; (c) to compare the effects of tobacco smoke exposure on the transcriptome in oral v. bronchial epithelium and (d) to identify agents with the potential to suppress the effects of tobacco smoke on the transcriptome.
Effects of cigarette smoke on the human oral mucosal transcriptome.
Sex, Specimen part
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