The Inhibitory Effect of (-)-Epigallocatechin-3-Gallate on Breast Cancer Progression via Reducing Methylation and DNMT Activity.

Epigenetic modifications are important mechanisms responsible for cancer progression. Accumulating data suggest that (-)-epigallocatechin-3-gallate (EGCG), the most abundant catechin of green tea, may hamper carcinogenesis by targeting epigenetic alterations. We found that signal peptide-CUB (complement protein C1r/C1s, Uegf, and Bmp1)-EGF (epidermal growth factor) domain-containing protein 2 (), a tumor suppressor gene, was hypermethylated in breast tumors. However, it is unknown whether EGCG regulates methylation, and the mechanisms remain undefined. This study was designed to investigate the effect of EGCG on methylation in breast cancer cells. We reveal that EGCG possesses a significantly inhibitory effect on cell viability in a dose- and time-dependent manner and presents more effects than other catechins. EGCG treatment resulted in enhancement of the gene, along with elevated E-cadherin and decreased vimentin expression, leading to significant suppression of cell migration and invasion. The inhibitory effect of EGCG on knock-down cells was remarkably alleviated. Further study demonstrated that EGCG significantly decreased the methylation status by reducing DNA methyltransferase (DNMT) expression and activity. In summary, this study reported for the first time that methylation can be reversed by EGCG treatment, finally resulting in the inhibition of breast cancer progression. These results suggest the epigenetic role of EGCG and its potential implication in breast cancer therapy.