The cyclooxygenase inhibitor sulindac sulfide inhibits EP4 expression and suppresses the growth of glioblastoma cells.
EP4 expression in human glioblastoma cells correlates with growth on soft agar. The cyclooxygenase inhibitor sulindac sulfide first altered specificity protein-1 (Sp-1) and early growth response gene-1 expression, then increased the expression of nonsteroidal anti-inflammatory drug-activated gene 1 and activating transcription factor 3, and then decreased EP4 expression. EP4 suppression was dependent on blocking the Sp-1 binding sites in the human EP4 promoter. Mutation in the Sp-1 sites in EP4 altered the promoter activity and abolished sulindac sulfide effects. The inhibitory effect of sulindac sulfide on EP4 expression was reversed by PD98059, a mitogen-activated protein/extracellular signal-regulated kinase kinase-1/extracellular signal-regulated kinase inhibitor. Sp-1 phosphorylation was dependent on sulindac sulfide-induced Erk activation. Chromatin immunoprecipitation assay confirmed that Sp-1 phosphorylation decreases Sp-1 binding to DNA and leads to the suppression of EP4. Inhibition of cell growth on soft agar assay was found to be a highly complex process and seems to require not only the inhibition of cyclooxygenase activity but also increased expression of nonsteroidal anti-inflammatory drug-activated gene 1 and activating transcription factor 3 and suppression of EP4 expression. Our data suggest that the suppression of EP4 expression by sulindac sulfide represents a new mechanism for understanding the tumor suppressor activity.
Kambe
Atsushi
A
Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA.
Yoshioka
Hiroki
H
Kamitani
Hideki
H
Watanabe
Takashi
T
Baek
Seung Joon
SJ
Eling
Thomas E
TE
D051700:Activating Transcription Factor 3 / Q000378:metabolism; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000473:pathology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D047369:Chromatin Immunoprecipitation; D003114:Colony-Forming Units Assay; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D051766:Early Growth Response Protein 1 / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D047468:Immunoprecipitation; D008156:Luciferases / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D018078:Receptors, Prostaglandin E / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D058309:Receptors, Prostaglandin E, EP4 Subtype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013467:Sulindac / Q000031:analogs & derivatives* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D051700:Activating Transcription Factor 3; D000894:Anti-Inflammatory Agents, Non-Steroidal; D016861:Cyclooxygenase Inhibitors; D051766:Early Growth Response Protein 1; D005419:Flavonoids; C117339:NBAS protein, human; D009363:Neoplasm Proteins; C545650:PTGER4 protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018078:Receptors, Prostaglandin E; D058309:Receptors, Prostaglandin E, EP4 Subtype; D016329:Sp1 Transcription Factor; D013467:Sulindac; C025462:sulindac sulfide; D008156:Luciferases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one