Biochemical and biophysical research communications
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Biochem. Biophys. Res. Commun. · Mar 2005
Quercetin, a potent inhibitor against beta-catenin/Tcf signaling in SW480 colon cancer cells.
Dysregulation of Wnt/beta-catenin pathway plays a central role in early events in colorectal carcinogenesis. We examined the effect of quercetin, a famous anti-tumor agent, against beta-catenin/Tcf signaling in SW480 cells. Quercetin inhibited the transcriptional activity of beta-catenin/Tcf in SW480 and also in HEK293 cells transiently transfected with constitutively active mutant beta-catenin gene, whose product is not induced to be degraded by APC-Axin-GSK3beta complex, so we concluded that its inhibitory mechanism was related to beta-catenin itself or downstream components. ⋯ Immunoprecipitation analysis also showed that the binding of beta-catenin to Tcf-4 was also disrupted by quercetin. Western blot analysis proved these decreased bindings resulted from decreased level of beta-catenin and Tcf-4 product in nucleus caused by quercetin. Together, we suggest that quercetin is an excellent inhibitor of beta-catenin/Tcf signaling in SW480 cell lines, and the reduced beta-catenin/Tcf transcriptional activity is due to the decreased nuclear beta-catenin and Tcf-4 proteins.