Green tea polyphenol (−)‐epigallocatechin‐3‐gallate inhibits cyclooxygenase‐2 expression in colon carcinogenesis
- 28 February 2006
- journal article
- research article
- Published by Wiley in Molecular Carcinogenesis
- Vol. 45 (5), 309-319
- https://doi.org/10.1002/mc.20166
Abstract
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 downregulated 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 κB (NF-κB) 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.Keywords
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