Promoter demethylation of WIF-1 by epigallocatechin-3-gallate in lung cancer cells.

Abstract

Aberrant promoter methylation of Wnt inhibitory factor-1 (WIF-1) is a fundamental mechanism of epigenetic silencing in human cancers. Epigallocatechin-3-gallate (EGCG) has been reported to directly reactivate several methylation-silenced genes. The promoter demethylation and reactivation of WIF-1 has not previously been reported. Methylation-specific PCR, sequencing analysis and RT-PCR analysis were performed to evaluate promoter demethylation of WIF-1 and WIF-1 expression, Western blot analysis and luciferase reporter assay were performed to evaluate expression of cytosolic beta-catenin protein and Tcf/Lef reporter activity. Promoter demethylation of WIF-1 and restoration of WIF-1 expression after EGCG treatment are demonstrated in H460 and A549 cell lines. EGCG also decreased cytosolic beta-catenin protein level and inhibited Tcf/Lef reporter activity. These results suggest the potential therapeutic use of EGCG for the reversal of WIF-1 promoter methylation.