Effect of NDRG3 expression on cell response to hypoxia
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ABSTRACT: Analysis of Huh-7 hepatocarcinoma cell line depleted of NDRG3 or HIF-1α under hypoxic condition. HIF-1α and NDRG3 have distinct functions in hypoxia responses. Results provide insight into molecular basis of HIF-independent signaling in the development and progression of hypoxic tumors Gene expression profiles of Huh-7 cells stably expressing NDRG3-shRNA or HIF-1α-shRNA under normoxia were compared to gene expression profiles of Huh-7 stable cells under hypoxia for 3, 6, 12 and 24 hours.
Project description:Analysis of Huh-7 hepatocarcinoma cell line depleted of NDRG3 or HIF-1α under hypoxic condition. HIF-1α and NDRG3 have distinct functions in hypoxia responses. Results provide insight into molecular basis of HIF-independent signaling in the development and progression of hypoxic tumors Gene expression profiles of Huh-7 cells stably expressing NDRG3-shRNA or HIF-1α-shRNA under normoxia were compared to gene expression profiles of Huh-7 stable cells under hypoxia for 6, 12 and 24 hours.
Project description:Analysis of Huh-7 hepatocarcinoma cell line depleted of NDRG3 or HIF-1α under hypoxic condition. HIF-1α and NDRG3 have distinct functions in hypoxia responses. Results provide insight into molecular basis of HIF-independent signaling in the development and progression of hypoxic tumors
Project description:Analysis of Huh-7 hepatocarcinoma cell line depleted of NDRG3 or HIF-1α under hypoxic condition. HIF-1α and NDRG3 have distinct functions in hypoxia responses. Results provide insight into molecular basis of HIF-independent signaling in the development and progression of hypoxic tumors
Project description:Activation of glycolytic genes by HIF-1 is considered critical for metabolic adaptation to hypoxia. We found that HIF-1 also actively suppresses glucose metabolism through the tricarboxylic acid cycle (TCA) by directly trans-activating the gene encoding pyruvate dehydrogenase kinase 1 (PDK1). PDK1 inactivates the TCA cycle enzyme, pyruvate dehydrogenase (PDH), which converts pyruvate to acetyl-CoA. Forced PDK1 expression in hypoxic HIF-1α-null cells increases ATP levels, attenuates hypoxic ROS generation and rescues these cells from hypoxia-induced apoptosis. These studies reveal a novel hypoxia-induced metabolic switch that shunts glucose metabolites from the mitochondria to glycolysis to maintain ATP production and to prevent toxic ROS production. Experiment Overall Design: We sought to determine by microarray analysis of gene expression the genes responsive to hypoxia using the human B lymphocyte cell line, P493-6. Hypoxia-responsive genes were globally assessed in cells incubated in 0.1% O2 for 29 hours at which the highest HIF-1 levels were obtained
Project description:Analysis of HeLa cells overexpressing NDRG3 or exposed to hypoxic condition. Gene expression profiles of HeLa cells stably expressing NDRG3 were compared to gene expression profiles of HeLa stable cells expressing mock or hypoxia-mediated gene expression profiles.
Project description:To investigate the role for LSD1 under hypoxia condition. we depleted LSD1 gene with siRNA in Huh-1 cell lines under 1% O2 hypoxia condtion, and than perforemed gene expression microarray analysis. Using Gene Set Enrichment Analysis (GSEA), determined to identify the biological pathway. Determined the gene expression profile of the LSD konckdown effect under hypoxia condition. Using Gene Set Enrichment Analysis (GSEA) decided to identify the biological pathways.
Project description:Hypoxia is an important condition in the tumor cell microenvironment and approximately 1-1.5% of the genome is transcriptionally responsive to hypoxia with hypoxia-inducible factor-1 (HIF-1) as a major mediator of transcriptional activation. Tumor hypoxia is associated with a more aggressive phenotype of many cancers in adults, but data on pediatric tumors are scarce. By immunohistochemical analysis, HIF-1α expression was readily detectable in 18/28 primary Ewing´s sarcoma family tumors (ESFT), a group of highly malignant bone-associated tumors in children and young adults, which encouraged us to study the effect of hypoxia on ESFT cell lines in vitro. Many tumors are profoundly hypoxic and multiple studies have demonstrated that hypoxic tumors have a poorer prognosis than non-hypoxic tumors. The cellular adaptations of cancer cells to hypoxia have been shown to profoundly influence transcriptional regulation. Intriguingly, we found that EWS-FLI1 protein expression, which characterizes ESFT, is up-regulated by hypoxia in a HIF-1α-dependent manner. Hypoxia modulated the EWS-FLI1 transcriptional signature relative to normoxic conditions. Both synergistic as well as antagonistic transcriptional effects of EWS-FLI1 and of hypoxia were observed. Consistent with alterations in the expression of metastasis related genes, hypoxia stimulated the invasiveness and soft-agar colony formation of ESFT cells in vitro. Our data represents the first transcriptome analysis of hypoxic ESFT cells and identifies hypoxia as an important microenvironmental factor modulating EWS-FLI1 expression and target gene activity with far-reaching consequences for the malignant properties of ESFT. Experiment Overall Design: We analysed the consequences of hypoxia on gene expression in two ESFT cell lines (SK-N-MC, TC252) grown as multicellular spheroids and as adherent monolayers.
Project description:Chronic hypoxia induces pulmonary vascular remodeling and pulmonary hypertension (PH). While it is established that transcription factors, hypoxia-inducible factors (HIF-1α/HIF-2α) activate gene programs that drive hypoxia-induced PH, the mechanism of HIF-1/2 activation is less clear. Here, we report that carboxylterminus of Hsp70-interacting protein (CHIP or Stub1) modulates HIF-1α and HIF-2α transcription rather than reducing their stability. Knocking-down Stub1 reduced hypoxic activation of HIF-1α mRNA, protein, and activity while enhancing hypoxic induction of HIF-2α mRNA, protein, and target genes in pulmonary vascular cells. Mechanistically, CBP/p300-mediated acetylation of lysine (K287) inactivates the ubiquitin ligase activity of Stub1 and triggers its translocation from the cytoplasm into the nucleus. There, it recognizes the HIF promoter and hypoxia response elements (HREs) in target genes. Expression of Stub1-K287Q mutant (mimicking acetylation) enhanced hypoxia-induced HIF-1α expression, while acetyl-deficient Stub1-K287R mutant had the opposite effect on HIF-α but enhanced hypoxia-induced HIF-2α transcriptional activity. Endothelial-Stub1 transgenic mice tolerated chronic hypoxia better, had less pulmonary vascular remodeling, reduced pulmonary vascular resistance, and greater cardioprotection. Thus, Stub1 nuclear translocation enhances hypoxic induction of HIF-1α activity while suppressing deleterious effects of HIF-2α. These observations indicate that nuclear-Stub1 synergizes with HIF-1α to promote transcriptional responses and antagonizes HIF2α-driven PH in chronic hypoxia.
Project description:The adaptive responses to oxygen depletion orchestrated by hypoxia-inducible factors (HIFs) produce profound effects on multiple pathways. A canonical metabolic response is enhanced fermentation, but this can generate an unfavorably acidic environment under poor capillary perfusion. It is unclear how cells balance the metabolic benefits of hypoxic responses against knock-on consequences on acid-base homeostasis. We studied the interplay between hypoxia and acidosis on HIF signaling in colorectal cancer cell lines that can survive acidic conditions. Hypoxia stabilized HIF-1α, but this effect was transient in combination with acidosis. By 48 h, HIF-1α induction decreased in proportion to acidification. Proteomic analyses identified responses that followed HIF-1α, including canonical HIF targets (CA9, PDK1), but these did not reflect a proteome-wide downregulation. Responses to acidosis and hypoxia were enriched in lysosomal proteins, but not proteasomal components, implicating the former degradation pathway in transient HIF-1α activation under acidosis. Moreover, HIF-1α decay was not due to decreased HIF1A transcription but was blocked by lysosomal inactivation (bafilomycin-A1). Acidotic hypoxia increased the abundance of lysosomes and activated autophagy by disabling the inhibitory influence of mammalian target of rapamycin complex 1, resulting in HIF-1α degradation. By blocking HIF-driven fermentative upregulation, this mechanism protects the cellular environment from deleterious acid-overloading, an outcome that outweighs the biosynthetic benefits of raised glycolytic flux under suppressed respiration. Thus, alkaline conditions are permissive for at least some aspects of HIF-1α signaling, but may not reflect tumor microenvironment chemistry. Consequently, acidic hypoxic tumor regions may not necessarily overlay with sites of HIF induction
Project description:Hypoxia-inducible factor 1 (HIF-1) is a transcriptional regulator that mediates cellular adaptive responses to hypoxia. Hypoxia-inducible factor 1α (HIF-1α) is involved in the development of ascites syndrome (AS) in broiler chickens. Therefore, studying the effect of HIF-1α on the cellular transcriptome under hypoxic conditions will help to better understand the mechanism of HIF-1α in the development of AS in broilers. In this study, we analyzed the gene expression profile of the DF-1 cell line under hypoxic conditions by RNA-seq. Additionally, we constructed the HIF-1α knockdown DF-1 cell line by using the RNAi method and analyzed the gene expression profile under hypoxic conditions. The results showed that exposure to hypoxia for 48 hours had a significant impact on the expression of genes in the DF-1 cell line, which related to cell proliferation, stress response, and apoptosis. In addition, after HIF-1α knockdown more differential expression genes appeared than in wild-type cells, and the expression of most hypoxia-related genes was either down-regulated or remained unchanged. Pathway analysis results showed that differentially expressed genes were mainly enriched in pathways related to cell proliferation, apoptosis, and oxidative phosphorylation. Our study obtained transcriptomic data from chicken fibroblasts at different hypoxic times and identified the potential regulatory network associated with HIF-1α. This data provides valuable support for understanding the transcriptional regulatory mechanism of HIF-1α in the development of AS in broilers.