title: Suppression of the hypoxia-inducible factor-1 response in cervical carcinoma xenografts by proteasome inhibitors.
abstract: Experimental data suggest therapeutic advantage from selective disruption of the hypoxia response. We recently found that the proteasome inhibitor bortezomib decreases tumor carbonic anhydrase IX (CAIX) expression in colon cancer patients and herein report a companion laboratory study to test if this effect was the result of hypoxia-inducible factor (HIF) inhibition. Human cervical (SiHa and Me180) and colon (RKO) carcinoma cell lines were treated with bortezomib or the structurally unrelated proteasome inhibitor MG132 in normoxic and hypoxic conditions in vitro. Two different in vivo experiments investigated bortezomib effects after single dose (2 mg/kg, 24 h) or longer exposure in severe combined immunodeficient mice bearing SiHa xenografts. Treatment with either drug produced accumulation of HIF-1alpha in vitro but strongly inhibited the production of CAIX and vascular endothelial growth factor (VEGF) under hypoxia. This correlated with more than 10-fold reduction in HIF-1 transcriptional activity under hypoxic conditions. A similar effect of bortezomib was seen in vivo, using the nitroimidazole probe EF5 to define regions of tumor hypoxia and a triple immunofluorescence technique to measure the spatial distributions of HIF-1alpha and CAIX. Plasma VEGF levels decreased by approximately 90% during treatment with bortezomib, indicating that this agent can potently inhibit the hypoxia response in tumors.
authors.affiliation: Division of Applied Molecular Oncology, Ontario Cancer Institute, Princess Margaret Hospital and University of Toronto, 610 University Avenue, Toronto, Ontario, Canada.
authors.forename: Diana C
authors.initials: DC
authors.lastname: Birle
authors.forename: David W
authors.initials: DW
authors.lastname: Hedley
mesh_terms: D000951:Antigens, Neoplasm / Q000096:biosynthesis; D000970:Antineoplastic Agents / Q000494:pharmacology; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000096:biosynthesis; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D015687:Cell Hypoxia / Q000502:physiology; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism; D050881:E1A-Associated p300 Protein / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007976:Leupeptins / Q000494:pharmacology*; D008297:Male; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology*; D011485:Protein Binding; D011719:Pyrazines / Q000494:pharmacology*; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis; D023041:Xenograft Model Antitumor Assays
chemical_list: D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D001897:Boronic Acids; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007976:Leupeptins; D011480:Protease Inhibitors; D011719:Pyrazines; D042461:Vascular Endothelial Growth Factor A; D000069286:Bortezomib; D050881:E1A-Associated p300 Protein; C494360:EP300 protein, human; D053148:Caspase 3; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde