Project description:The activation of the transcription factor Hypoxia-inducible factor-1 (HIF-1) plays an essential role in tumor development, tumor progression and resistance to chemo- and radiotherapy. In order to identify compounds targeting the HIF pathway, a small-molecule library was screened using a luciferase-driven HIF-1 reporter cell line under hypoxia. The high throughput screen led to the identification of a class of aminoalkyl-substituted compounds that inhibited hypoxia-induced HIF-1 target gene expression in human lung cancer cell lines at low nanomolar concentrations but did not affect expression levels of genes outside of the HIF-1 pathway. Lead structure BAY 87-2243 was found to inhibit HIF-1Î± protein accumulation under hypoxic conditions in NSCLC cell line H460 but had no effect on HIF-1Î± protein accumulation and HIF target gene expression in RCC4 cells lacking VHL activity or in H460 cells after inhibition of HIF prolyl hydroxylase activity. BAY 87-2243 had no effect on HIF-Î±-mRNA levels. Antitumor activity of BAY 87-2243 and suppression of HIF-1 target gene expression in vivo was demonstrated in a H460 xenograft model. BAY 87-2243 did not inhibit cell proliferation under standard conditions. However under glucose depletion, a condition favoring mitochondrial ATP generation as energy source, BAY 87-2243 inhibited cell proliferation in the nanomolar range. Further experiments revealed that BAY 87-2243 inhibits mitochondrial production of reactive oxygen species (ROS) by blocking complex I activity but has no effect on complex III activity. Lowering of mitochondrial ROS production to reduce hypoxia-induced HIF-1 activity in tumors might be an interesting therapeutic approach to overcome chemo- and radiotherapy-resistance of hypoxic tumors. We used microarrays to detail the global programme of gene expression that is induced in NSCLC cell line H460 upon hypoxia (16 h incubation at 1 % pO2) and evaluated a dose-dependent effect of our HIF-1-pathway inhibitor BAY 87-2243 on genes tthat are affected by hypoxia. Specificity of BAY 87-2243 for the suppression of HIF-1-mediated gene transcription on a genome-wide scale was evaluated by microarray hybridizations using Affymetrix GeneChip Human Gene 1.0 ST arrays. RNA from normoxic H460 cells and from hypoxic H460 cells incubated with 1, 10 and 100 nM BAY 87-2243 respectively was subjected to array hybridization. Of those 30 genes that were most strongly suppressed by 100 nM BAY 87-2243 in hypoxic H460 cells compared to DMSO-treated hypoxic H460 cells, virtually all of them are induced by prior hypoxia and most of these genes have been described in the literature as HIF-1 target genes

Project description:mRNA and microRNA expression was examined in global cellular fractions and in RNA-induced silencing complex (RISC)-immunoprecipitated cell fractions in cultured primary human astrocytes (ScienCell) and in cultured human U-87 MG astrocytoma cells (ATCC). ABSTRACT: Background: GW/P bodies are cytoplasmic ribonucleoprotein-rich foci that are involved in microRNA (miRNA)-mediated messenger RNA (mRNA) silencing and degradation. These mRNA regulatory functions within GW/P bodies are mediated by GW182 and its binding partner hAgo2 when bound to miRNA within the RNA-induced silencing complex (RISC). Although miRNAs and mRNAs are known to be localized to RISC in a variety of cells, to date no published study has examined the profile of specific miRNA and mRNA targeted to the RISC. Methodology/Principle Findings: In this study, RISC mRNA and miRNA components were profiled by microarray analysis of human U-87 astrocytoma cells and primary human astrocytes with total RNA extracted from the RISC as well as the global cellular fractions. The novel findings of this study were fourfold: (1) miRNAs are highly enriched in primary astrocyte RISC compared to U-87 astrocytoma RISC, (2) astrocytoma cells and primary astrocytes each contain unique RISC miRNA profiles as compared to their respective cellular miRNA profiles, (3) miR-195, 10b, 29b, 19b, 34a and 455-3p were upregulated and miR-181b was downregulated in U-87 astrocytoma RISC as compared to primary astrocyte RISC, and (4) RISC contain mostly downregulated mRNAs in primary astrocytes and U-87 astrocytoma cells. Conclusions/Significance: We show that in U-87 astrocytoma cells, miR-34a and miR-195 were upregulated in RISC suggesting an oncogenic role for these miRNAs. Three miR34a-targeted mRNAs and two miR-195-targeted mRNAs were downregulated. One miR-195-targeted mRNA was upregulated. Biological pathway analysis of RISC mRNA components suggests that the RISC plays a pivotal role in cancer, inflammatory disease, immunological disease, the cell cycle, cellular movement and numerous cell signaling pathways. This study points to the importance of the RISC and ultimately GW/P body composition and function and in miRNA and mRNA deregulation in astrocytoma cells and possibly for other brain tumors. Experiments outsourced to LC Sciences who are partnered with an AffymetrixM-BM-. Authorized Service Provider, SeqWright DNA Technology Services (Houston, TX). Using Affymetrix Human Genome U133A 2.0 Array, they analyzed 14,500 well-characterized human genes across 4 replicates in each of the 4 sample groups: (1) global cellular U-87 astrocytoma, (2) global cellular primary astrocyte, (3) RISC-IP U-87 astrocytoma, and (4) RISC-IP primary astrocyte. Experiments outsourced to LC Sciences (Houston, TX). Using M-BM-5Paraflo microfluidic chips, they analyzed 6211 target human miRNAs (Sanger miRBase version 11, http://microrna.sanger.ac.uk/sequences/) or control RNAs (array hybridization controls and single-base mismatch targets) and a polyethylene glycol spacer segment to extend the coding segment away from the substrate across 4 replicates in each of the 4 sample groups: (1) global cellular U-87 astrocytoma, (2) global cellular primary astrocyte, (3) RISC-IP U-87 astrocytoma, and (4) RISC-IP primary astrocyte.

Project description:The activation of the transcription factor Hypoxia-inducible factor-1 (HIF-1) plays an essential role in tumor development, tumor progression and resistance to chemo- and radiotherapy. In order to identify compounds targeting the HIF pathway, a small-molecule library was screened using a luciferase-driven HIF-1 reporter cell line under hypoxia. The high throughput screen led to the identification of a class of aminoalkyl-substituted compounds that inhibited hypoxia-induced HIF-1 target gene expression in human lung cancer cell lines at low nanomolar concentrations but did not affect expression levels of genes outside of the HIF-1 pathway. Lead structure BAY 87-2243 was found to inhibit HIF-1α protein accumulation under hypoxic conditions in NSCLC cell line H460 but had no effect on HIF-1α protein accumulation and HIF target gene expression in RCC4 cells lacking VHL activity or in H460 cells after inhibition of HIF prolyl hydroxylase activity. BAY 87-2243 had no effect on HIF-α-mRNA levels. Antitumor activity of BAY 87-2243 and suppression of HIF-1 target gene expression in vivo was demonstrated in a H460 xenograft model. BAY 87-2243 did not inhibit cell proliferation under standard conditions. However under glucose depletion, a condition favoring mitochondrial ATP generation as energy source, BAY 87-2243 inhibited cell proliferation in the nanomolar range. Further experiments revealed that BAY 87-2243 inhibits mitochondrial production of reactive oxygen species (ROS) by blocking complex I activity but has no effect on complex III activity. Lowering of mitochondrial ROS production to reduce hypoxia-induced HIF-1 activity in tumors might be an interesting therapeutic approach to overcome chemo- and radiotherapy-resistance of hypoxic tumors. We used microarrays to detail the global programme of gene expression that is induced in NSCLC cell line H460 upon hypoxia (16 h incubation at 1 % pO2) and evaluated a dose-dependent effect of our HIF-1-pathway inhibitor BAY 87-2243 on genes tthat are affected by hypoxia.

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Vindija 87

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