Ibuprofen-mediated reduction of hypoxia-inducible factors HIF-1alpha and HIF-2alpha in prostate cancer cells.
OBJECTIVE
Hypoxia-inducible factors HIF-1alpha and HIF-2alpha are considered to be potential targets for antineoplastic therapy because they regulate the expression of genes that contribute to tumor cell survival, aggressiveness, and angiogenesis. Nonsteroidal anti-inflammatory drugs (NSAIDs) have gained considerable interest as anticancer agents because of their cytotoxic and antiangiogenic properties. The aim of this study was to investigate whether NSAIDs inhibit HIFs and HIF-regulated gene expression in prostate cancer cells.


METHODS
PC3 and DU-145 cells were treated with ibuprofen (Ibu) and other NSAIDs under normoxic and hypoxic (95% N(2), 5% CO(2); <10 ppm O(2)) conditions. The effect of NSAIDs on HIF proteins was analyzed by Western blot analysis. HIF-regulated proteins, vascular endothelial growth factor (VEGF) and glucose transporter-1 (Glut-1), were analyzed by ELISA and Western blot analysis, respectively.


RESULTS
Exposure of PC3 and DU-145 cells to hypoxic condition up-regulated HIF-1alpha and HIF-2alpha proteins. Treatment with Ibu under normoxic and hypoxic conditions reduced the level of HIF-1alpha and HIF-2alpha. Ibu-mediated down-regulation of HIFs was associated with down-regulation of HIF-regulated proteins VEGF and Glut-1 in cells exposed to hypoxia. Other nonspecific NSAIDs, diclofenac and ketorolac, also inhibited HIF-1alpha and HIF-2alpha. The reduction in HIFs was observed in PC3 cells that expressed cyclooxygenase-2 (COX-2) protein as well as in DU-145 cells, which did not express COX-2 protein. COX-2-specific inhibitor NS-398 did not inhibit HIF-1alpha or VEGF and GLUT-1.


CONCLUSIONS
These data indicate that one of the effects of NSAIDs is to reduce HIF protein levels. The inhibition of HIFs by NSAIDs was COX-2 independent.
Palayoor
Sanjeewani T
ST
Radiation Oncology Branch, Center for Cancer Research and the Molecular Radiation Therapeutics Branch, Division of Cancer Treatment and Diagnosis, National Cancer Institute, NIH, Bethesda, Maryland, 20892-1002, USA.
Tofilon
Philip J
PJ
Coleman
C Norman
CN
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D051792:Basic Helix-Loop-Helix Proteins; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000627:therapeutic use; D004008:Diclofenac / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D051272:Glucose Transporter Type 1; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007052:Ibuprofen / Q000627:therapeutic use*; D007527:Isoenzymes / Q000096:biosynthesis; D020910:Ketorolac / Q000627:therapeutic use; D008297:Male; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis; D009578:Nitrobenzenes / Q000627:therapeutic use; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis; D011471:Prostatic Neoplasms / Q000378:metabolism*; D013449:Sulfonamides / Q000627:therapeutic use; D013997:Time Factors; D015534:Trans-Activators / Q000096:biosynthesis*; D014157:Transcription Factors / Q000096:biosynthesis*; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000378:metabolism; D000099162:Endothelial PAS Domain-Containing Protein 1
D000894:Anti-Inflammatory Agents, Non-Steroidal; D051792:Basic Helix-Loop-Helix Proteins; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D004008:Diclofenac; D051272:Glucose Transporter Type 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007052:Ibuprofen; D007527:Isoenzymes; D020910:Ketorolac; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D009578:Nitrobenzenes; D011451:Prostaglandin-Endoperoxide Synthases; D013449:Sulfonamides; D015534:Trans-Activators; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human; C495677:SLC2A1 protein, human; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; C496540:PTGS2 protein, human