Prostaglandin E2 induces hypoxia-inducible factor-1alpha stabilization and nuclear localization in a human prostate cancer cell line.
Hypoxia-induced up-regulation of vascular endothelial growth factor (VEGF) expression is a critical event leading to tumor neovascularization. Hypoxia stimulates hypoxia-inducible factor-1alpha (HIF-1alpha), a transcriptional activator of VEGF. Cyclooxygenase (COX)-2, an inducible enzyme that catalyzes the formation of prostaglandins (PGs) from arachidonic acid, is also induced by hypoxia. We reported previously that COX-2 inhibition prevents hypoxic up-regulation of VEGF in human prostate cancer cells and that prostaglandin E(2) (PGE(2)) restores hypoxic effects on VEGF. We hypothesized that PGE(2) mediates hypoxic effects on VEGF by modulating HIF-1alpha expression. Addition of PGE(2) to PC-3ML human prostate cancer cells had no effect on HIF-1alpha mRNA levels. However, PGE(2) significantly increased HIF-1alpha protein levels, particularly in the nucleus. This effect of PGE(2) largely results from the promotion of HIF-1alpha translocation from the cytosol to the nucleus. PGE(2) addition to PC-3 ML cells transfected with a GFP-HIF-1alpha vector induced a time-dependent nuclear accumulation of the HIF-1alpha protein. Two selective COX-2 inhibitors, meloxicam and NS398, decreased HIF-1alpha levels and nuclear localization, under both normoxic and hypoxic conditions. Of several prostaglandins tested, only PGE(2) reversed the effects of a COX-2 inhibitor in hypoxic cells. Finally, PGE(2) effects on HIF-1alpha were specifically inhibited by PD98059 (a MAPK inhibitor). These data demonstrate that PGE(2) production via COX-2-catalyzed pathway plays a critical role in HIF-1alpha regulation by hypoxia and imply that COX-2 inhibitors can prevent hypoxic induction of HIF-mediated gene transcription in cancer cells.
Liu
Xin Hua
XH
Department of Medicine, Annenberg Building Room 23-78, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA. liux01@doc.mssm.edu
Kirschenbaum
Alexander
A
Lu
Min
M
Yao
Shen
S
Dosoretz
Amy
A
Holland
James F
JF
Levine
Alice C
AC
D021581:Active Transport, Cell Nucleus; D016718:Arachidonic Acid / Q000378:metabolism; D002384:Catalysis; D002467:Cell Nucleus / Q000378:metabolism; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism*; D016228:Endothelial Growth Factors / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D015151:Immunoblotting; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism*; D008164:Luminescent Proteins / Q000378:metabolism; D008222:Lymphokines / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D000077239:Meloxicam; D008565:Membrane Proteins; D009578:Nitrobenzenes / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011453:Prostaglandins / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000473:pathology*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013449:Sulfonamides / Q000494:pharmacology; D013843:Thiazines / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016895:Culture Media, Serum-Free; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D016228:Endothelial Growth Factors; D004791:Enzyme Inhibitors; D005419:Flavonoids; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins; D007527:Isoenzymes; D008164:Luminescent Proteins; D008222:Lymphokines; D008565:Membrane Proteins; D009578:Nitrobenzenes; D011453:Prostaglandins; D012333:RNA, Messenger; D013449:Sulfonamides; D013843:Thiazines; D013844:Thiazoles; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D049452:Green Fluorescent Proteins; D016718:Arachidonic Acid; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019869:Phosphatidylinositol 3-Kinases; D015232:Dinoprostone; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077239:Meloxicam