title: Laurenditerpenol, a new diterpene from the tropical marine alga Laurenciaintricata that potently inhibits HIF-1 mediated hypoxic signaling in breast tumor cells.
abstract: The degree of tumor hypoxia correlates with advanced disease stages and treatment resistance. The transcription factor hypoxia-inducible factor-1 (HIF-1) promotes tumor cell adaptation and survival under hypoxic conditions. Therefore, specific HIF-1 inhibitors represent an important new class of potential tumor-selective therapeutic agents. A T47D human breast tumor cell-based reporter assay was used to examine extracts of plants and marine organisms for inhibitors of HIF-1 activation. Bioassay-guided fractionation of the lipid extract of the red alga Laurencia intricata yielded a structurally novel diterpene, laurenditerpenol (1). The structure of 1 was determined spectroscopically. The relative configurations of the substituents of each ring system were assigned on the basis of NOESY correlations. The absolute configuration of position C-1 was determined by the modified Mosher ester procedure (directly in NMR tubes). Compound 1 potently inhibited hypoxia-activated HIF-1 (IC50: 0.4 microM) and hypoxia-induced VEGF (a potent angiogenic factor) in T47D cells. Compound 1 selectively inhibits HIF-1 activation by hypoxia but not iron chelator-induced activation. Further, 1 suppresses tumor cell survival under hypoxic conditions without affecting normoxic cell growth. Compound 1 inhibits HIF-1 by blocking the induction of the oxygen-regulated HIF-1alpha protein. Mitochondrial respiration studies revealed that 1 suppresses oxygen consumption.
authors.affiliation: Department of Pharmacognosy, National Center for Natural Products Research, and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, Mississippi 38677-1848, USA.
authors.forename: Kaleem A
authors.initials: KA
authors.lastname: Mohammed
authors.forename: Chowdhury Faiz
authors.initials: CF
authors.lastname: Hossain
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Richard K
authors.initials: RK
authors.lastname: Bruick
authors.forename: Yu-Dong
authors.initials: YD
authors.lastname: Zhou
authors.forename: Dale G
authors.initials: DG
authors.lastname: Nagle
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001943:Breast Neoplasms; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors*; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D000860:Hypoxia; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008928:Mitochondria / Q000378:metabolism; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors*; D000461:Rhodophyta / Q000737:chemistry*; D013237:Stereoisomerism; D014157:Transcription Factors / Q000037:antagonists & inhibitors*
chemical_list: D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D004224:Diterpenes; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D014157:Transcription Factors; C496938:laurenditerpenol