title: Green tea polyphenol (-)-epigallocatechin-3-gallate inhibits cyclooxygenase-2 expression in colon carcinogenesis.
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 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.
authors.affiliation: Department of Pathology and Microbiology, School of Medicine, The University of South Carolina, and South Carolina Cancer Center, Columbia, South Carolina 29203, USA.
authors.forename: Guang
authors.initials: G
authors.lastname: Peng
authors.forename: Dan A
authors.initials: DA
authors.lastname: Dixon
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Muga
authors.forename: Theresa J
authors.initials: TJ
authors.lastname: Smith
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wargovich
mesh_terms: D015153:Blotting, Western; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D003110:Colonic Neoplasms / Q000201:enzymology / Q000235:genetics*; D051546:Cyclooxygenase 2 / Q000235:genetics* / Q000378:metabolism; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D017930:Genes, Reporter / Q000187:drug effects; D006801:Humans; D020935:MAP Kinase Signaling System; D016328:NF-kappa B / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013662:Tea
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D016328:NF-kappa B; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate; D051546:Cyclooxygenase 2; D019869:Phosphatidylinositol 3-Kinases