title: Intermittent hypoxia confers pro-metastatic gene expression selectively through NF-κB in inflammatory breast cancer cells.
abstract: Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer. Treatment options are limited and the mechanisms underlying its aggressiveness are poorly understood. Intermittent hypoxia (IH) causes oxidative stress and is emerging as important regulator of tumor metastasis. Vessels in IBC tumors have been shown to be immature, which is a primary cause of IH. We therefore investigated the relevance of IH for the modulation of gene expression in IBC cells in order to assess IH as potential regulator of IBC aggressiveness. Gene array analysis of IBC cells following chronic IH (45-60 days) demonstrated increased expression of pro-metastatic genes of the extracellular matrix, such as tenascin-C (TNC; an essential factor of the metastatic niche) and matrix metalloproteinase 9 (MMP9), and of pro-inflammatory processes, such as cyclooxygenase-2 (COX-2). Investigating the oxidative stress-dependent regulation of TNC, we found a gradual sensitivity on mRNA and protein levels. Oxidative stress activated NF-E2-related factor 2 (Nrf2), c-Jun N-terminal kinase (JNK), c-Jun and nuclear factor κB (NF-κB), but TNC upregulation was only dependent on NF-κB activation. Pharmacological inhibition of inhibitor of NF-κB α (IκBα) phosphorylation as well as overexpression of IκBα prevented TNC, MMP9 and COX-2 induction, whereas the pro-inflammatory cytokine interleukin-1β (IL-1β) increased their expression levels. Analysis of the gene array data showed NF-κB binding sites for 64% of all upregulated genes, linking NF-κB with IH-dependent regulation of pro-metastatic gene expression in IBC cells. Our results provide a first link between intermittent hypoxia and pro-metastatic gene expression in IBC cells, revealing a putative novel mechanism for the high metastatic potential of IBC.
authors.affiliation: Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland; Department of Gynecology, University Hospital of Zurich, 8091 Zurich, Switzerland.
authors.forename: Katrin
authors.initials: K
authors.lastname: Gutsche
authors.affiliation: Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland.
authors.forename: Elisa B
authors.initials: EB
authors.lastname: Randi
authors.affiliation: Lady Davis Institute for Medical Research, Department of Medicine & Department of Physiology, McGill University, Montreal, Quebec, Canada H3T 1E2.
authors.forename: Volker
authors.initials: V
authors.lastname: Blank
authors.affiliation: Department of Gynecology, University Hospital of Zurich, 8091 Zurich, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fink
authors.affiliation: Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland.
authors.forename: Roland H
authors.initials: RH
authors.lastname: Wenger
authors.affiliation: Department Women and Children, Cantonal Hospital Baden, 5404 Baden, Switzerland. Electronic address: cornelia.leo@ksb.ch.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Leo
authors.affiliation: Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland. Electronic address: carsten.scholz@uzh.ch.
authors.forename: Carsten C
authors.initials: CC
authors.lastname: Scholz
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000873:Anthracenes / Q000494:pharmacology; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D042361:Mammary Glands, Human / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D020780:Matrix Metalloproteinase 9 / Q000235:genetics* / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics* / Q000378:metabolism; D009362:Neoplasm Metastasis; D009570:Nitriles / Q000494:pharmacology; D018384:Oxidative Stress; D010100:Oxygen / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D016755:Proto-Oncogene Proteins c-jun / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013450:Sulfones / Q000494:pharmacology; D019063:Tenascin / Q000235:genetics* / Q000378:metabolism
chemical_list: C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; D000873:Anthracenes; C508585:IL1B protein, human; D053583:Interleukin-1beta; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; C495635:NFE2L2 protein, human; D009570:Nitriles; D016755:Proto-Oncogene Proteins c-jun; D013450:Sulfones; D019063:Tenascin; D000072000:NF-KappaB Inhibitor alpha; C432165:pyrazolanthrone; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D048031:JNK Mitogen-Activated Protein Kinases; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9; D010100:Oxygen; D000111:Acetylcysteine
keywords: Inflammatory breast cancer; Intermittent hypoxia; NF-κB; Oxidative stress; ROS; Reactive oxygen species; Tenascin-C