Many traditional cytotoxic agents used in the treatment of cancer function by eliciting an apoptotic response in tumor cells. However, evasion of apoptosis by BCL-2 family members is often deregulated prior to therapeutic intervention leading to treatment failure. To address this, ABT-737 was rationally designed to target BCL-2-like family members and has shown promising results against tumor cells dependent on BCL-2 for their survival. One shortcoming is that MCL-1, a member of the BCL-2 family is poorly inhibited by ABT-737 and is a major cause of resistance. To gain insight into biological pathways that could circumvent this resistance, we designed an shRNA screen to identify novel sensitizers to ABT-737 by engineering MYC driven lymphomas that were resistant to ABT-737 due to endogenous MCL-1 expression. Utilizing this model, we performed a shRNA drop-out screen and identified Dhx9 as a target whose suppression sensitizes cells to ABT-737. DHX9 loss lead to replicative stress signaling, which in turn potently induced the BH3-only proteins, NOXA and PUMA, in a p53-dependent manner to curtail MCL-1 activity. Induction of NOXA is essential for ABT-737 sensitization. Our results ascribe a novel role for DHX9 in the replicative stress pathway and link DHX9 activity to p53 function in vivo.
RNAi screening uncovers Dhx9 as a modifier of ABT-737 resistance in an Eμ-myc/Bcl-2 mouse model.
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View SamplescJun is a transcription factor activated by phosphorylation by SAPK/JNK MAP kinase pathway that has been linked to atherosclerosis. Adenovirus mediated gene transfer of a dominant negative form of cJun in C57BL/6 mice increased greatly the apolipoprotein E (ApoE) mRNA and plasma apoE levels and induced dyslipidmia, characterized by increased plasma cholesterol, triglyceride and VLDL levels and accumulation of discoidal HDL particles. Unexpectedly, infection of ApoE-/- mice with adenovirus expressing dn-cJun reduced by 50% plasma cholesterol, suggesting that the dn-cJun affected other genes that control plamsa cholesterol. To determine the molecular pathways implicated in this process we performed whole genome expression profiling using total RNA from the liver of infected ApoE-/- mice.
A dominant negative form of the transcription factor c-Jun affects genes that have opposing effects on lipid homeostasis in mice.
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View SamplesIn order to define the transcriptional network functionally regulated by Pax8 as well as infer its direct targets, we performed RNAi to knock-down Pax8 gene in FRTL-5 thyroid cells. Expression data from three independent silencing experiments were analyzed by microarray technology unraveling 2815 genes differentially expressed between silenced cells and controls. Of these, 1421 genes were down-regulated and 1394 genes were up-regulated 72hrs after Pax8 silencing.
Identification of novel Pax8 targets in FRTL-5 thyroid cells by gene silencing and expression microarray analysis.
Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
A novel crosstalk between CCAR2 and AKT pathway in the regulation of cancer cell proliferation.
Cell line
View SamplesCCAR2 is a nuclear protein recently emerged as a pivotal player of the DNA damage response since it has been found involved in both apoptosis induction and DNA repair. Differently, its role in tumorigenesis and cancer progression is still elusive. In our studies we found that CCAR2 depletion impairs the proliferation of human cancer cell lines, but leaves unaffected the growth of normal immortalized cells. To better investigate this point we performed a genome wide gene expression analyses in U2OS and BJ-hTERT depleted of CCAR2 and we found that loss of this protein causes the deregulation of genes implicated in the AKT pathway specifically in U2OS cells, but not in BJ-hTERT. In accordance with these results we found a reduction in AKT activation in all the tested cancer cell lines depleted of CCAR2, but not in the normal ones. The defective activation of AKT is caused by the upregulation of TRB3 gene in cancer cells depleted of CCAR2 and finally results in the reduction of GSK3 phosphorylation, prevention of G1/S transition and inhibition of cancer cell growth.
A novel crosstalk between CCAR2 and AKT pathway in the regulation of cancer cell proliferation.
Cell line
View SamplesCCAR2 is a nuclear protein recently emerged as a pivotal player of the DNA damage response since it has been found involved in both apoptosis induction and DNA repair. Differently, its role in tumorigenesis and cancer progression is still elusive. In our studies we found that CCAR2 depletion impairs the proliferation of human cancer cell lines, but leaves unaffected the growth of normal immortalized cells. To better investigate this point we performed a genome wide gene expression analyses in U2OS and BJ-hTERT depleted of CCAR2 and we found that loss of this protein causes the deregulation of genes implicated in the AKT pathway specifically in U2OS cells, but not in BJ-hTERT. In accordance with these results we found a reduction in AKT activation in all the tested cancer cell lines depleted of CCAR2, but not in the normal ones. The defective activation of AKT is caused by the upregulation of TRB3 gene in cancer cells depleted of CCAR2 and finally results in the reduction of GSK3 phosphorylation, prevention of G1/S transition and inhibition of cancer cell growth.
A novel crosstalk between CCAR2 and AKT pathway in the regulation of cancer cell proliferation.
Cell line
View SamplesTo investigate the genes differentially expressed upon plating on top of matrixes with different stiffness, we compared the expression profiles of MDA-MB-231 breast cancer cells plated on a stiff substrate (plastic) with the same cells plated on a soft substrate (hydrogels 0.7 kPa).
Mechanical cues control mutant p53 stability through a mevalonate-RhoA axis.
Cell line
View SamplesProliferation of neoplastic plasma cells within the bone marrow leads to reduced oxygen availability. In response to hypoxia, the transcription factor hypoxia-inducible factor-2alpha (HIF-2) is activated and stabilised. We hypothesise that activation of HIF-2 is a central driver of multiple myeloma disease progression, leading to the induction of transcription of genes associated with angiogenesis, osteoclast activation and cell migration. In this study we assessed the affects of HIF-2 overexpression on gene expression in the human myeloma cell line LP-1.
HIF-2α Promotes Dissemination of Plasma Cells in Multiple Myeloma by Regulating CXCL12/CXCR4 and CCR1.
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View SamplesPericytes derived from skin dermis can substantially enhance the short-term tissue-regenerative capacity of human epidermal cells already committed to differentiation; they also display both phenotypic and functional properties of mesenchymal stem cells. In this microarray analysis, we compared the gene expression profile of dermal pericytes to that of the remaining dermal cells of neonatal human foreskin.
A role for pericytes as microenvironmental regulators of human skin tissue regeneration.
Specimen part
View SamplesWe profiled basal and bicuculline+4-AP inducible mRNA expression in cultured mouse hippocampal neurons with or without viral shRNA mediated knockdown of Kdm6b Overall design: We harvested mRNA from neurons under four conditions (pLKO vector/treatment control, pLKO vector/3hr bicuculline+4AP, Kdm6b knockdown/treatment control,Kdm6b knockdown/3hr bicuculline+4AP). Libraries were generated and used for RNA sequencing.
The histone lysine demethylase Kdm6b is required for activity-dependent preconditioning of hippocampal neuronal survival.
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