The cyclooxygenase inhibitor sulindac sulfide inhibits EP4 expression and suppresses the growth of glioblastoma cells

Cancer Prev Res (Phila). 2009 Dec;2(12):1088-99. doi: 10.1158/1940-6207.CAPR-09-0140. Epub 2009 Nov 24.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Activating Transcription Factor 3 / metabolism
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacology*
  • Blotting, Western
  • Brain Neoplasms / pathology*
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
  • Chromatin Immunoprecipitation
  • Colony-Forming Units Assay
  • Cyclooxygenase Inhibitors / pharmacology*
  • Early Growth Response Protein 1 / metabolism
  • Flavonoids / pharmacology
  • Glioblastoma / pathology*
  • Humans
  • Immunoprecipitation
  • Luciferases / metabolism
  • Mitogen-Activated Protein Kinase 3 / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • Mitogen-Activated Protein Kinases / metabolism
  • Neoplasm Proteins / metabolism
  • Phosphorylation
  • Promoter Regions, Genetic / genetics
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / pharmacology
  • Receptors, Prostaglandin E / antagonists & inhibitors*
  • Receptors, Prostaglandin E / genetics
  • Receptors, Prostaglandin E / metabolism
  • Receptors, Prostaglandin E, EP4 Subtype
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sp1 Transcription Factor / metabolism
  • Sulindac / analogs & derivatives*
  • Sulindac / pharmacology
  • Tumor Cells, Cultured

Substances

  • Activating Transcription Factor 3
  • Anti-Inflammatory Agents, Non-Steroidal
  • Cyclooxygenase Inhibitors
  • Early Growth Response Protein 1
  • Flavonoids
  • NBAS protein, human
  • Neoplasm Proteins
  • PTGER4 protein, human
  • RNA, Messenger
  • RNA, Small Interfering
  • Receptors, Prostaglandin E
  • Receptors, Prostaglandin E, EP4 Subtype
  • Sp1 Transcription Factor
  • Sulindac
  • sulindac sulfide
  • Luciferases
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one