Recent data demonstrate that extracellular signals are transmitted through a network of proteins rather than hierarchical signaling pathways. This network model suggests why inhibition of a single component of a canonical pathway, even when targeting a mutationally activated driver of cancer, has insufficiently dramatic effects on the treatment of cancer. The biological outcome of signals propagated through a network is inherently more robust and resistant to inhibition of a single network component due to compensatory and redundant signaling events. In this study, we performed a functional chemical genetic screen analogous to synthetic lethal screening in yeast genetics to identify novel interactions between signaling inhibitors that would not be predicted based on our current understanding of signaling networks. We screened over 300 drug combinations in nine melanoma cell lines and have identified pairs of compounds that show synergistic cytotoxicity. Among the most robust and surprising results was synergy between sorafenib, a multi-kinase inhibitor with activity against Raf, and diclofenac, a non-steroidal anti-inflammatory drug (NSAID). This synergy did not correlate with the known RAS and BRAF mutational status of the melanoma cell lines. The NSAIDs celecoxib and ibuprofen could qualitatively substitute for diclofenac. Similarly, the MEK inhibitor PD325901 and the Raf inhibitor RAF265 could qualitatively substitute for sorafenib. These drug substitution experiments suggest that inhibition of cyclo-oxygenase and MAP kinase signaling are components of the observed synergistic cytotoxicity. Genome-wide expression profiling demonstrates synergy-specific down-regulation of survival-related genes. This study provides proof of principle that synthetic lethal screening can uncover novel functional drug combinations and suggests that the underlying signaling networks that control responses to targeted agents can vary substantially depending on unexplored components of the cell genotype.
Synthetic lethal screening with small-molecule inhibitors provides a pathway to rational combination therapies for melanoma.
Cell line, Treatment
View SamplesWe used Affymetrix microarrays to investigate gene expression changes in the liver of lean female Zucker rats exposed to a normal diet supplemented with a rosemary extract rich in the diterpenic compound, carnosic acid (CA).
A rosemary extract enriched in carnosic acid improves circulating adipocytokines and modulates key metabolic sensors in lean Zucker rats: Critical and contrasting differences in the obese genotype.
Sex, Specimen part, Treatment, Time
View SamplesNon-symbiotic hemoglobins are ubiquitously expressed proteins known to interact with nitric oxide, an inhibitor of mitochondrial respiration and an important signalling component. We evaluated the underlying molecular mechanisms of AtHb1 (also referred as AtGLB1 or AHb1) function, its effects on stress response and the interplay with nitric oxide. For this purpose, AtHb1 was overexpressed in Arabidopsis thaliana under control of the seed-specific promoter LeB4.
Seed-specific elevation of non-symbiotic hemoglobin AtHb1: beneficial effects and underlying molecular networks in Arabidopsis thaliana.
Specimen part, Treatment
View SamplesThe clinical impact of aberrant CEBPA promoter methylation (PM) in AML is controversial discussed. The aim of this study was to clarify the significance of aberrant CEBPA PM with regard to clinical features in a cohort of 572 de novo AML with wildtype CEBPA and normal karyotype. The distal promoter was methylated in 54/572 cases (9.41%) whereas proximal PM was never detected. Methylation of the core promoter was detected in only 8 of 326 cases (2.45%) and thus seems to be a rare event in AML. There was no correlation between CEBPA distal PM, age, sex, white blood cell (WBC) count or Hb levels at diagnosis. We also were not able to detect a significant correlation between the presence of CEBPA distal PM and molecular mutations such as FLT3-ITD, NPM1, AML1, MLL-PTD and IDH1. Solely the frequency of IDH2R140 mutations was significantly reduced in CEBPA distal PM positive compared to CEBPA distal PM negative cases (p=0.01). Furthermore, analysis of CEBPA mRNA expression level revealed no difference between CEBPA distal PM positive and CEBPA distal PM negative cases, suggesting that CEBPA distal PM has no influence on CEBPA expression. CEBPA distal PM did not show impact on overall survival (OS), event free survival (EFS) or incidence of relapse. Also when other mutations were taken into regard no prognostic impact of CEBPA distal PM could be shown. In contrast, a distinct expression profile of CEBPA distal PM positive cases compared to CEBPA mutated and CEBPA distal PM negative cases was observed. In addition, a significantly higher frequency of CEBPA distal PM was detected in RUNX1-RUNX1T1 positive AML compared to the CEBPA witdtype cases. We conclude that the presence of aberrant CEBPA PM has no clinical relevance and is therefore a negligible prognostic marker in de novo AML with normal karyotype.
Frequency and prognostic impact of CEBPA proximal, distal and core promoter methylation in normal karyotype AML: a study on 623 cases.
Disease
View SamplesEmbryonic stem (ES) cells and ES cell-derived progeny characterized by nestin expression (including neural progenitors) were studied (three independent experiments). The mouse ES cell line R1 was cultured on a feeder layer of mouse embryonic fibroblasts (FL). ES cells were differentiated into nestin-positive cells for 4+8 days and 4+11 days according to the differentiation protocol by Rolletschek et al. (Mechanisms of Development 105, 93-104, 2001).
Pluripotency associated genes are reactivated by chromatin-modifying agents in neurosphere cells.
No sample metadata fields
View SamplesThe understanding of metastatic spread is limited and molecular mechanisms causing particular characteristics of metastasis, like varying dormancy periods of Mets originating from the same primary tumor entity or the differing number of Mets in patients with the same primary tumor, are largely unknown. Knowing the molecular fundamentals of these phenomena would support the prognosis of patients outcome and facilitate the decision for an appropriate therapy regime.
Gene signatures of pulmonary metastases of renal cell carcinoma reflect the disease-free interval and the number of metastases per patient.
Sex
View SamplesAcute myeloid leukemia (AML) with CEBPA mutations is determined as provisional entity in the current WHO. A difference in clinical outcome between single- (sm) and double-mutated (dm) cases has been reported, whereupon dm cases were shown to be associated with longer overall survival (OS). The occurrence and prognostic impact of concomitant molecular mutations in addition to CEBPAdm has not been assessed until now. Here, we investigated a cohort of 95 AML CEBPAdm cases for concomitant mutations. TET2 was found to be the most frequent mutation (32/94, 34.0%), followed by GATA2 (20/95, 21.0%), WT1 (13/95, 13.7%), DNMT3A (9/94, 9.6%), ASXL1 (9/95, 9.5%), NRAS (8/95, 8.4%), KRAS (3/94, 3.2%), IDH1/2 (6/95, 6.3%), FLT3-ITD (6/95, 6.3%), FLT3-TKD (2/95, 2.1%), NPM1 (2/95, 2.1%), and RUNX1 (1/94). No mutation was detected in MLL-PTD and TP53. With respect to prognostic impact, we observed that those cases harboring additional mutations in TET2 showed significant worse survival than wild-type cases (P=0.035), whereas GATA2 mutated cases showed improved survival (P=0.032). Further, using gene expression microarray analysis we identified no clear different clustering within the CEBPAdm cases with the distinct concomitant mutated genes. In conclusion, we demonstrated that 76.8% of CEBPAdm cases harbored additional alterations in other molecular markers and that CEBPA is a suitable MRD marker to control therapy.
CEBPA double-mutated acute myeloid leukaemia harbours concomitant molecular mutations in 76·8% of cases with TET2 and GATA2 alterations impacting prognosis.
Disease, Disease stage
View SamplesThe understanding of metastatic spread is limited and molecular mechanisms causing particular characteristics of metastasis are largely unknown. This comprises the extremely varying dormancy periods of tumor cells in the secondary organ after metastatic spread, represented by the disease-free survival (DFS) of the patients, or differing numbers of metastases in different patients. Knowing the molecular fundamentals of these phenomena would support the individual prediction of patients outcome and facilitate the decision for an appropriate monitoring and therapy regime.
CD31, EDNRB and TSPAN7 are promising prognostic markers in clear-cell renal cell carcinoma revealed by genome-wide expression analyses of primary tumors and metastases.
Sex, Specimen part, Disease stage
View SamplesGenes relevant to manifestion of and variation in aggression behavior might be differentially expressed in lines selected for divergent levels of aggression.
Quantitative genomics of aggressive behavior in Drosophila melanogaster.
No sample metadata fields
View SamplesThe goal of this experiment was to explore the extent of KIN10 (At3g01090) transcriptional regulation and identify its early target genes in Arabidopsis mesophyll protoplasts. Results suggest that KIN10 targets a remarkably broad array of genes that orchestrate transcription networks, promote catabolism and autophagy, and suppress anabolism and ribosome biogenesis. The transient expression condition ruled out secondary or long-term effects of metabolism and growth, and circumvented experimental limitations caused by redundancy and embryonic lethality observed in mammals and plants.
A central integrator of transcription networks in plant stress and energy signalling.
No sample metadata fields
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