title: Effects of HIF-1 inhibition by chetomin on hypoxia-related transcription and radiosensitivity in HT 1080 human fibrosarcoma cells.
abstract: BACKGROUND
  Hypoxia-inducible factor-1 (HIF-1) overexpression has been linked to tumor progression and poor prognosis. We investigated whether targeting of HIF-1 using chetomin, a disrupter of the interaction of HIF-1 with the transcriptional coactivator p300, influences the radiosensitivity of hypoxic HT 1080 human fibrosarcoma cells.
  
  
  METHODS
  Optimal dose of chetomin was determined by EGFP-HRE gene reporter assay in stably transfected HT 1080 cells. Cells were assayed for expression of the hypoxia-inducible genes carbonic anhydrase 9 (CA9) and vascular endothelial growth factor (VEGF) by RT-PCR and for clonogenic survival after irradiation with 2, 5 or 10 Gy, under normoxic or hypoxic (0.1% O2, 12 h) conditions in the presence or absence of chetomin (150 nM, 12 h, pre-treatment of 4 h).
  
  
  RESULTS
  Chetomin treatment significantly reduced CA9 and VEGF mRNA expression in hypoxic cells to 44.4 +/- 7.2% and 39.6 +/- 16.0%, respectively, of untreated hypoxic controls. Chetomin clearly reduced the modified oxygen enhancement ratio (OER') compared to untreated cells, from 2.02 to 1.27, from 1.86 to 1.22 and from 1.49 to 1.06 at the 50%, 37% and 10% clonogenic survival levels, respectively.
  
  
  CONCLUSIONS
  HIF-1 inhibition by chetomin effectively reduces hypoxia-dependent transcription and radiosensitizes hypoxic HT 1080 human fibrosarcoma cells in vitro.
authors.affiliation: Department of Radiation Oncology, University of Würzburg, 97080 Würzburg, Germany. staab_a@klinik.uni-wuerzburg.de
authors.forename: Adrian
authors.initials: A
authors.lastname: Staab
authors.forename: Jürgen
authors.initials: J
authors.lastname: Loeffler
authors.forename: Harun M
authors.initials: HM
authors.lastname: Said
authors.forename: Désirée
authors.initials: D
authors.lastname: Diehlmann
authors.forename: Astrid
authors.initials: A
authors.lastname: Katzer
authors.forename: Melanie
authors.initials: M
authors.lastname: Beyer
authors.forename: Markus
authors.initials: M
authors.lastname: Fleischer
authors.forename: Franz
authors.initials: F
authors.lastname: Schwab
authors.forename: Kurt
authors.initials: K
authors.lastname: Baier
authors.forename: Hermann
authors.initials: H
authors.lastname: Einsele
authors.forename: Michael
authors.initials: M
authors.lastname: Flentje
authors.forename: Dirk
authors.initials: D
authors.lastname: Vordermark
mesh_terms: D002256:Carbonic Anhydrases / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D015687:Cell Hypoxia / Q000502:physiology*; D045744:Cell Line, Tumor; D004220:Disulfides / Q000494:pharmacology*; D005354:Fibrosarcoma / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000187:drug effects*; D026121:Indole Alkaloids / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D011836:Radiation Tolerance / Q000187:drug effects*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics
chemical_list: D004220:Disulfides; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D026121:Indole Alkaloids; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C001598:chetomin; D002256:Carbonic Anhydrases