Green tea polyphenol (-)-epigallocatechin-3-gallate inhibits cyclooxygenase-2 expression in colon carcinogenesis

Mol Carcinog. 2006 May;45(5):309-19. doi: 10.1002/mc.20166.


Tea, one of the most widely consumed beverages worldwide, has been shown to have anti-cancer activity in various cancers including colon cancer. It has been demonstrated that overexpression of the inducible isoform of cyclooxygenase (COX-2) occurs during colon tumorigenesis and inhibition of COX-2 by non-steroidal anti-inflammatory drugs (NSAIDs) is chemopreventive. To determine whether the anti-cancer effect associated with green tea impacted COX-2 expression levels, human colorectal cancer cell lines HT-29 and HCA-7, were treated with (-)-epigallocatechin-3-gallate (EGCG), the most abundant and effective polyphenol of green tea. EGCG significantly inhibited constitutive COX-2 mRNA and protein overexpression. The inhibitory effects of EGCG on signaling pathways controlling COX-2 expression were examined. We observed that EGCG down regulated the ERK1/2 and Akt pathways in colon cancer cells. The effect of EGCG on COX-2 expression resulted in decreased COX-2 promoter activity via inhibition of nuclear factor kappaB (NF-kappaB) activation. EGCG also promoted rapid mRNA decay mediated through the COX-2 3'untranslated region (3'UTR). In conclusion, these data suggest that inhibition of COX-2 is a mechanism for the anti-proliferative effect of green tea and emphasizes the role that dietary factors have as anti-cancer agents.

Publication types

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

MeSH terms

  • Blotting, Western
  • Catechin / analogs & derivatives*
  • Catechin / pharmacology
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cell Transformation, Neoplastic / drug effects
  • Colonic Neoplasms / enzymology
  • Colonic Neoplasms / genetics*
  • Cyclooxygenase 2 / genetics*
  • Cyclooxygenase 2 / metabolism
  • Cyclooxygenase 2 Inhibitors / pharmacology*
  • Enzyme Induction / drug effects
  • Gene Expression Regulation, Enzymologic / drug effects*
  • Genes, Reporter / drug effects
  • Humans
  • MAP Kinase Signaling System
  • NF-kappa B / metabolism
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism
  • RNA, Messenger / metabolism
  • RNA, Neoplasm / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tea


  • Cyclooxygenase 2 Inhibitors
  • NF-kappa B
  • RNA, Messenger
  • RNA, Neoplasm
  • Tea
  • Catechin
  • epigallocatechin gallate
  • Cyclooxygenase 2
  • Phosphatidylinositol 3-Kinases