Unknown,Transcriptomics,Genomics,Proteomics

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Expression data from Hif 2alpha Knockdown study

ABSTRACT: Non-small cell lung cancer (NSCLC) is the leading cause of cancer deaths worldwide. The oxygen-sensitive Hypoxia Inducible Factor (HIF) transcriptional regulators HIF-1Î± and HIF-2Î± are overexpressed in many human NSCLCs, and constitutive HIF-2Î± activity can promote murine lung tumor progression, suggesting that HIF proteins may be effective NSCLC therapeutic targets. To investigate the consequences of inhibiting HIF activity in lung cancers, we deleted Hif-1Î± or Hif-2Î± in an established KrasG12D-driven murine NSCLC model. Deletion of Hif-1Î± had no obvious effect on tumor growth, whereas Hif-2Î± deletion resulted in an unexpected increase in tumor burden that correlated with reduced expression of the candidate tumor suppressor gene Scgb3a1 (HIN-1). Here, we identify Scgb3a1 as a direct HIF-2Î± target gene, and demonstrate that HIF-2Î± regulates Scgb3a1 expression and tumor formation in human KrasG12D-driven NSCLC cells. AKT pathway activity, reported to be repressed by Scgb3a1, was enhanced in HIF-2Î± deficient human NSCLC cells and xenografts. Finally, a direct correlation between HIF-2Î± and SCGB3a1 expression was observed in approximately 70% of human NSCLC samples analyzed. These data suggest that whereas HIF-2Î± overexpression can contribute to NSCLC progression, therapeutic inhibition of HIF-2Î± below a critical threshold may paradoxically promote tumor growth by reducing expression of tumor suppressor genes, including Scgb3a1. RNA was isolated from tumors of experimental (Hif2alpha deficient) mice and control mice (seven for each group).

ORGANISM(S): Mus musculus

SUBMITTER: Tyler Jacks

PROVIDER: E-GEOD-22575 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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

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Expression data from Hif 2alpha Knockdown study

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