title: 3,3'-diindolylmethane reduces levels of HIF-1alpha and HIF-1 activity in hypoxic cultured human cancer cells.
abstract: 3,3'-diindolylmethane (DIM) is a chemopreventive and chemotherapeutic phytochemical derived from the metabolism of indoles found at high concentrations in cruciferous vegetables. We have previously shown that DIM exhibits anti-angiogenic properties in cultured vascular endothelial cells and in Matrigel plug assays in rodents. In the present study, we demonstrate that DIM reduces the level of hypoxia-inducible factor (HIF)-1alpha in hypoxic tumor cell lines, as well as HIF-1 transcriptional activity as measured by a reporter assay. Moreover, DIM inhibited the expression of HIF-1-responsive endogenous genes, resulting in the reduced expression of key hypoxia responsive factors, VEGF, furin, enolase-1, glucose transporter-1 and phosphofructokinase. DIM reduced the level of HIF-1alpha in hypoxic cells by increasing the rate of the prolylhydroxylase- and proteasome-mediated degradation of HIF-1alpha, and by decreasing the rate of HIF-1alpha transcription. Using enzyme kinetics studies, we established that DIM interacts with the oligomycin-binding site on the F0 transmembrane component of mitochondrial F1F0-ATPase. The contributions of the resulting increases in levels of ROS and O2 in hypoxic cells to the inhibitory effects of DIM on HIF-1alpha expression are discussed. These studies are the first to show that DIM can decrease the accumulation and activity of the key angiogenesis regulatory factor, HIF-1alpha, in hypoxic tumor cells.
authors.affiliation: Department of Nutritional Sciences and Toxicology, 217 Morgan Hall, University of California, Berkeley, CA 94720, USA.
authors.forename: Jacques E
authors.initials: JE
authors.lastname: Riby
authors.forename: Gary L
authors.initials: GL
authors.lastname: Firestone
authors.forename: Leonard F
authors.initials: LF
authors.lastname: Bjeldanes
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007211:Indoles / Q000494:pharmacology*; D008156:Luciferases / Q000235:genetics; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
chemical_list: D016588:Anticarcinogenic Agents; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007211:Indoles; D017382:Reactive Oxygen Species; D008156:Luciferases; D006180:Proton-Translocating ATPases; C016392:3,3'-diindolylmethane