Nordihydroguaiaretic acid restores expression of silenced E-cadherin gene in human breast cancer cell lines and xenografts

In our study we use nordihydroguaiaretic acid (NDGA), the naturally occurring lignan, to investigate whether it plays a role in the prevention and treatment of cancer by epigenetic modifications. The growth inhibitory effect of NDGA on human breast cancer cell lines was determined using the MTT assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay). It substantially inhibited the growth of human breast cancer cell lines SKBR3 and MDA-MB-435 with an estimated IC50 of 31.09 +/- 1.6 and 38.8 +/- 2.1 mu mol/l respectively, after 4 days incubation with different NDGA concentrations. The in-vivo anticancer activity of NDGA was evaluated by calculating the tumor growth inhibition value. NDGA substantially inhibited the growth of human breast carcinoma cells in both animal and cell-based models. We also found that a single treatment with NDGA reactivates methylation-silenced E-cadherin gene in vitro and in vivo, suggesting an intriguing concept that lignans may act as natural effective epigenetic modifiers in the prevention and treatment of cancer.