Document Detail

Lipid rafts mediate epigallocatechin-3-gallate- and green tea extract-dependent viability of human colon adenocarcinoma COLO 205 cells; clusterin affects lipid rafts-associated signaling pathways.
MedLine Citation:
PMID:  22100846     Owner:  NLM     Status:  In-Data-Review    
Epigallocatechin-3-gallate (EGCG) is an important bioactive constituent of green tea extract (GTE) that was widely believed to reduce proliferation of many cancer cell lines. The purpose of this study was to verify the possible pro-apoptotic action of GTE/EGCG in human colon adenocarcinoma COLO 205 cells. The effect of EGCG/GTE treatments on cell viability was studied using methyl thiazolyl tetrazolium (MTT) assay. Cell proliferation was assessed with crystal violet staining, whereas protein expression levels were evaluated by western blotting followed by densitometric analysis. Obtained results were analyzed statistically. Surprisingly, EGCG/GTE dose-dependently up-regulated COLO 205 cells viability and proliferation. Observed effects were mediated by lipid rafts, as cholesterol depletion significantly prevented EGCG/GTE-dependent cell survival. Furthermore, treatment of COLO 205 cells with EGCG/GTE resulted in activation of MEK/ERK1/2, but not Akt1/2/GSK-3β signaling pathway. The presence of MEK inhibitor - PD98059 but not PI3-K inhibitor - LY294002, both reduced EGCG/GTE-induced ERK1/2 activation and the proliferative effect of catechins. Furthermore, EGCG/GTE stimulated secretory clusterin (sClu) expression level, which underwent complex control through lipid rafts/PKC/Wnt/β-catenin system. Our studies demonstrated that EGCG and GTE stimulate cell survival and proliferation of COLO 205 cells in a lipid rafts-dependent manner via at least MEK/ERK1/2 signaling pathway. Furthermore, EGCG/GTE mediated positive effects on viability and mitogenicity of COLO 205, while suppression of β-catenin activity was positively correlated with sClu clusterin expression.
B Pajak; E Kania; B Gajkowska; A Orzechowski
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of physiology and pharmacology : an official journal of the Polish Physiological Society     Volume:  62     ISSN:  1899-1505     ISO Abbreviation:  J. Physiol. Pharmacol.     Publication Date:  2011 Aug 
Date Detail:
Created Date:  2011-11-21     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9114501     Medline TA:  J Physiol Pharmacol     Country:  Poland    
Other Details:
Languages:  eng     Pagination:  449-59     Citation Subset:  IM    
Department of Cell Ultrastructure, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.
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