title: Dexamethasone impairs hypoxia-inducible factor-1 function.
abstract: Hypoxia-inducible factor-1 (HIF-1) is a heterodimeric transcription-factor composed of alpha- and beta-subunits. HIF-1 is not only necessary for the cellular adaptation to hypoxia, but it is also involved in inflammatory processes and wound healing. Glucocorticoids (GC) are therapeutically used to suppress inflammatory responses. Herein, we investigated whether GC modulate HIF-1 function using GC receptor (GR) possessing (HepG2) and GR deficient (Hep3B) human hepatoma cell cultures as model systems. Dexamethasone (DEX) treatment increased HIF-1alpha levels in the cytosol of HepG2 cells, while nuclear HIF-1alpha levels and HIF-1 DNA-binding was reduced. In addition, DEX dose-dependently lowered the hypoxia-induced luciferase activity in a reporter gene system. DEX suppressed the hypoxic stimulation of the expression of the HIF-1 target gene VEGF (vascular endothelial growth factor) in HepG2 cultures. DEX did not reduce hypoxically induced luciferase activity in HRB5 cells, a Hep3B derivative lacking GR. Transient expression of the GR in HRB5 cells restored the susceptibility to DEX. Our study discloses the inhibitory action of GC on HIF-1 dependent gene expression, which may be important with respect to the impaired wound healing in DEX-treated patients.
authors.affiliation: Institute of Physiology, University of Luebeck, Ratzeburger Allee 160, D-23538 Luebeck, Germany.
authors.forename: A E
authors.initials: AE
authors.lastname: Wagner
authors.forename: G
authors.initials: G
authors.lastname: Huck
authors.forename: D P
authors.initials: DP
authors.lastname: Stiehl
authors.forename: W
authors.initials: W
authors.lastname: Jelkmann
authors.forename: T
authors.initials: T
authors.lastname: Hellwig-Bürgel
mesh_terms: D000693:Anaerobiosis; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D003907:Dexamethasone / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000819:agonists / Q000378:metabolism
chemical_list: D005938:Glucocorticoids; D051793:Hypoxia-Inducible Factor 1; D011965:Receptors, Glucocorticoid; D003907:Dexamethasone