Indomethacin-induced apoptosis in esophageal adenocarcinoma cells involves upregulation of Bax and translocation of mitochondrial cytochrome C independent of COX-2 expression

Neoplasia. Jul-Aug 2000;2(4):346-56. doi: 10.1038/sj.neo.7900097.

Abstract

The prolonged use of nonsteroidal anti-inflammatory drugs (NSAIDs) has been shown to exert a chemopreventive effect in esophageal and other gastrointestinal tumors. The precise mechanism by which this occurs, however, is unknown. While the inhibition of COX-2 as a potential explanation for this chemopreventive effect has gained a great deal of support, there also exists evidence supporting the presence of cyclooxygenase-independent pathways through which NSAIDs may exert their effects. In this study, immunohistochemical analysis of 29 Barrett's epithelial samples and 60 esophageal adenocarcinomas demonstrated abundant expression of the COX-2 protein in Barrett's epithelium, but marked heterogeneity of expression in esophageal adenocarcinomas. The three esophageal adenocarcinoma cell lines, Flo-1, Bic-1, and Seg-1, also demonstrated varying expression patterns for COX-1 and COX-2. Indomethacin induced apoptosis in all three cell lines, however, in both a time- and dose-dependent manner. In Flo-1 cells, which expressed almost undetectable levels of COX-1 and COX-2, and in Seg-1, which expressed significant levels of COX-1 and COX-2, indomethacin caused upregulation of the pro-apoptotic protein Bax. The upregulation of Bax was accompanied by the translocation of mitochondrial cytochrome c to the cytoplasm, and activation of caspase 9. Pre-treatment of both cell lines with the specific caspase 9 inhibitor, z-LEHD-FMK, as well as the broad-spectrum caspase inhibitor, z-VAD-FMK, blocked the effect of indomethacin-induced apoptosis. These data demonstrate that induction of apoptosis by indomethacin in esophageal adenocarcinoma cells is associated with the upregulation of Bax expression and mitochondrial cytochrome c translocation, and does not correlate with the expression of COX-2. This may have important implications for identifying new therapeutic targets in this deadly disease.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenocarcinoma / genetics
  • Adenocarcinoma / metabolism
  • Adenocarcinoma / pathology*
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Barrett Esophagus / genetics
  • Barrett Esophagus / pathology
  • Cyclooxygenase 2
  • Cytochrome c Group / metabolism*
  • Esophageal Neoplasms / genetics
  • Esophageal Neoplasms / metabolism
  • Esophageal Neoplasms / pathology*
  • Esophagus
  • Gene Expression Regulation, Neoplastic / drug effects*
  • Humans
  • Indomethacin / pharmacology*
  • Isoenzymes / genetics
  • Kinetics
  • Membrane Proteins
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Mucous Membrane / metabolism
  • Mucous Membrane / pathology
  • Prostaglandin-Endoperoxide Synthases / genetics*
  • Protein Transport / drug effects
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins c-bcl-2*
  • Reverse Transcriptase Polymerase Chain Reaction
  • bcl-2-Associated X Protein

Substances

  • BAX protein, human
  • Cytochrome c Group
  • Isoenzymes
  • Membrane Proteins
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-2-Associated X Protein
  • Cyclooxygenase 2
  • PTGS2 protein, human
  • Prostaglandin-Endoperoxide Synthases
  • Indomethacin