Unknown,Transcriptomics,Genomics,Proteomics

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Pathway simulations in common oncogenic drivers of leukemic and rhabdomyosarcomatic cells: a systems biology approach

ABSTRACT: A part of current research has intensively been focused on the proliferation and metabolic processes governing biological systems. Since the advent of high throughput methodologies like microarrays, the load of genomic data has increased geometrically and along with that the need for computational methods which will interpret these data. In the present work we study in vitro the common proliferation and metabolic processes, which are combined to the common oncogenic pathways, as far as gene expression is concerned, between the T-cell acute lymphoblastic leukemia (CCRF-CEM) and the rhabdomyosarcoma (TE-671) cell lines. We present a computational approach, using cDNA microarrays, in order to identify commonalities between diverse biological systems. Our analysis predicted that JAK1, STAT1, PIAS2 and CDK4 are the driving forces in the two cell lines. This type of analysis can lead to the understanding of the common mechanisms that transform physiological cells to malignant, as well as it reveals a new holistic way to understandthe the dynamics of tumor onset as well as the mechanistics of oncogenic drivers. The present work is concerned with the common expressional profile of two cell lines: the T-cell acute lymphoblastic leukemia (CCRF-CEM) and the rhabdomyosarcoma (TE-671) cell lines. Our investigation was focused on the identification of genes that share a common expression profile between the two cell lines. Both cell lines are characterized by the fact that their differentiation has stopped at an early stage, before they mature to their final cell type. Normally, these cells would have matured and progressed into differentiated cells, constituting blood and muscle cells, respectively. At some unknown point, normal differentiation ceased for these cells and they became malignant. From that point on, to the first manifestation of symptoms of malignancy, there is a lack of knowledge regarding the mechanisms underlying oncogenesis. From these observations, the question whether two distinct cell types destined to fulfill different functions, manifest similar mechanisms of growth and progression due to their malignant character, arises. The present study was focused on the identification of the differential expression profiles underlying the two cell lines. A previous report studied the expression profile of seven ARMS cell lines possessing the PAX3-FKHR fusion gene, along with other cell lines of different tumor types (22). To our knowledge, this is the first time that a comparison between two totally different types of neoplasia, such as the CCRF-CEM and TE-671 cell lines, is attempted. These mechanisms are examined with purpose to identify common drivers that lead to the progression of tumor cells. We hereby propose a new computational approach for the investigation of common oncogenic drivers.

ORGANISM(S): Homo sapiens

SUBMITTER: George Lambrou

PROVIDER: E-GEOD-34522 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: Glucocorticoids are important pharmaceutical agents in the treatment of acute lymphoblastic leukemia in children. Resistance or sensitivity to glucocorticoids is considered to be of crucial importance for disease prognosis. Prednisolone is a first-line chemotherapeutic agent in the treatment of acute lymphoblastic leukemia. Here, the effects of prednisolone on the resistant CCRF-CEM leukemic cell line were studied. Methods: Prednisolone’s cytotoxic and cell cycle effects were studied with flow cytometry. NF-κB translocation was studied with Western Blotting and differential gene expression was studied with cDNA microarrays. Results: Prednisolone exerted a delayed biphasic effect, necrotic at low doses and apoptotic at higher doses. At low doses, prednisolone exerted a pre-dominant mitogenic effect despite its induction on total cell death, while at higher doses, prednisolone’s mitogenic and cell death effects were counterbalanced. NF-κB was constitutively present in the nucleus. Early gene microarray analysis revealed 40 differentially expressed genes upon 4 hours of prednisolone’s exposure. Notable differences in gene regulation were observed between the lowest and the highest glucocorticoid doses. Prednisolone activated genes related to apoptosis/tumor suppression, cell cycle progression, metabolism and intra-/ extra-cellular signaling pathways. Conclusions: The mitogenic/biphasic effects of prednisolone are of clinical importance in the case of resistant leukemic cells. This approach might lead to the identification of gene candidates for future molecular drug targets in combination therapy with glucocorticoids, along with early markers for glucocorticoid resistance. Elucidation of the mechanisms of GC action may lead to identification of gene targets responsible for GC resistance. Key tools in this process are high-throughput technologies such as microarray-based gene expression analysis. For this purpose, the parental CCRF-CEM cell line was chosen as the system of study for the effects of prednisolone treatment. This is a T-cell leukemia cell line characterized by a mutation (L753F) on one GR gene allele that impairs ligand binding (Thompson and Johnson 2003). It is known that both the DNA and ligand binding domains of the GR are required in order to repress NF-κB transactivation (Wissink, van Heerde et al. 1997). Interestingly, concerning the question whether this mutation would affect GC resistance, it has been reported previously that both the GC-resistant as well as the GC-sensitive CCRF-CEM subclones express heterogeneous populations of the GR (GRwt/GRL753F) (Palmer and Harmon 1991; Powers, Hillmann et al. 1993). The CCRF-CEM cell line has been reported to be resistant to GCs, presumably due to the accumulation of more resistant variants after long periods of prolonged culture (Norman and Thompson 1977). It is possible that these cells are clonally inhomogeneous, as possibly the cells obtained in vivo by patients. Moreover, the large number of the CCRF-CEM subclone studies in the literature makes it difficult to choose an appropriate resistant cell model. In addition, the utilization of an in vitro system for this study offered reproducibility, an opportunity to closely examine intracellular signals and avoid interference from other in vivo-participating systems. Thus, the cell line used for this study was considered to be useful in studying GC action and resistance in leukemic cells. The aim of this work was to determine the cytotoxic, cell cycle phase distribution and early cancer-specific gene expression effects of prednisolone in CCRF-CEM cells, as an in vitro model of ALL resistance to glucocorticoids. The early gene expression profile allowed identification of genes initiating pivotal, early onset regulatory mechanisms activated by GC and excluded ensuing feedback responses and further downstream signals. Samples tested were in the form of a loop-design i.e. control vs. 10nM prednisolone (designated 0vs1) , 10nM prednisolone vs.700uM prednisolone (designated 1vs3) and control vs. 700uM prednisolone (designated 0vs3), the sum of the logarithms of the first two should equal the third. In other words if Rj,i is the ratio of the ith gene in the jth experiment then R0vs1,i+R1vs3,i=R0vs3,i. We tested this using a statistical test. We have applied an intensity-dependent z-score where the sum of the ratios was compared to the ratio of the third experiment. If the difference was significant genes, in a standard deviation threshold of ±1.5 in relative units, were rejected from further analysis (Kerr and Churchill 2001; Kerr and Churchill 2001; Altman and Hua 2006; Kerr and Churchill 2007).

Project description:(This section will be revisited in good time prior to publication, for final approval) Research within the field of functional genomics provides a more profound understanding of living organisms, by elucidating the interaction between genes and gene products. This is of increasing importance in many fields, and especially within cancer research. With the use of microarray technology, the gene expression of a vast number of genes can be measured simultaneously. This allows us insight into tumor biology, and an opportunity to obtain knowledge of diagnostic and prognostic value, as well as hints towards the causes of cancer. In this study the gene expression in a selection of human neuroendocrine (NE) and non-neuroendocrine tumor cell lines were compared. Both qualitative and quantitative methods were applied to get an insight into the NE tumor biology. NE cells are found in practically every organ and tissue in the body and are assigned to synthesize peptide hormones and take up amino acids and transform these into biogenic amines by carboxylation. NE tumors arise after malignant transformation of neuroendocrine cells and are usually highly differentiated and have a low growth rate, which makes this a high prevalence tumor type. These rather rare tumors characteristically express NE markers, such as chromogranin A, and contains characteristic dense-secretory core granules. By using cDNA microarray analysis, the gene expression profiles of various NE tumor cell lines (e. g. carcinoid, neuroblastoma, medullary thyroid carcinoma and endocrine pancreatic tumor) were compared with those of non-NE tumor cells. As a reference the commercially available Universal human RNA reference (Stratagene) was used. Verification of the results were done by real time RT-PCR analysis after the NE nature of the cell lines was stated by immunohistochemical, electron microscopic and light microscopic examinations. A large number of genes were differentially expressed in NE cell lines vs. the non-NE cell lines, and were found to be of interest in NE tumor biology. Some of these genes were previously known in NE tumor biology, whereas the vast majority of the specified genes are novel in the context of NE tumor biology. Genes with little previous information were also identified and thought to be an asset in the search of new NE markers. A feasible prospective of the study would be expansion with additional samples cell lines and a more thorough verification with real time RT-PCR analysis. This would enhance the credibility and thus the utility of the findings. Future studies on the biological functions of the candidate genes and the mechanisms of their regulation, will hopefully enable suggestions of new NE markers of prognostic or diagnostic value, and eventually new drug targets. Keywords: neuroendocrine, neuroendocrine markers, gene expression profiling, cDNA microarray The hybridisation was performed by an experienced laboratory technician Eli Helge, (Dept. of Laboratory Medicine, Children`s and Women`s health, NTNU) at the microarray core facility. Three separate runs with 10, 11 and 3 slides was needed to obtain the 20 hybridisations (dyeswap x 10 cell lines) planned for this study. Of the 10 cell lines 6 were neuroendocrine and 4 were non-neuroendocrine. For comparison between these two groups the universal human reference RNA (Stratagene) was used as the "control" on each slide. An adapted version of the 3DNA Array 350 protocol (Genisphere) was used. The slides were scanned with a ScanArrayTMExpressHT (Packard BioScience) twice immediately after the hybridisation was completed to avoid photo bleaching of the fluorescent dyes.

Project description:It is now well established that mature mammalian spermatozoa carry a population of mRNA molecules, at least some of which are transferred to the oocyte at fertilisation. However, the function of the sperm transcriptome remains largely unclear. To shed light on the evolutionary conservation of this feature of sperm biology, we analysed highly purified populations of mature sperm from the fruitfly, Drosophila melanogaster. As with mammalian sperm, we found a consistently enriched population of mRNA molecules that are not likely to be derived from contaminating somatic cells or immature sperm. Using tagged transcripts for three of the spermatozoal mRNAs, we demonstrate that they are transferred to the oocyte at fertilisation and can be detected at least until the onset of zygotic gene expression. We find a remarkable conservation in the functional annotations associated with fly and human spermatozoal mRNAs, in particular a highly significant enrichment for transcripts encoding Ribosomal Proteins. The identification of a conserved set of spermatozoal transcripts opens the possibility of using the power of Drosophila genetics to address the function of this enigmatic class of molecules. RNA extracted from three biological replicates of purified sperm (Sperm rep1, Sperm rep2 and Sperm rep3) was used as a template for oligo-dT-primed reverse transcription, amplification, labelling of dye swapped technical replicates and hybridisation to long oligonucleotides microarrays. As a control, RNA from two biological replicates of dissected adult testis plus accessory glands (Testis_rep1, Testis_rep2) was amplified, labelled (dye-swap technical replicate) and hybridised to similar arrays. To help with the spot-finding of the arrays genomic DNA was co-hybridised in some cases (this genomic DNA data was excluded from further analysis). Genes with an intensity level below 200 in at least one channel across the Sperm or Testis set were removed (5579 transcripts present in all three sperm replicates, 5358 transcripts from the testis/accessory gland samples and 4295 transcripts common to both data sets). Then the quantile normalisation was independently applied to the Sperm replicate samples and Testis replicates.

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Pathway simulations in common oncogenic drivers of leukemic and rhabdomyosarcomatic cells: a systems biology approach

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