Liquiritigenin decreases tumorigenesis by inhibiting DNMT activity and increasing BRCA1 transcriptional activity in triple-negative breast cancer.

As a selective estrogen receptor β agonist, the natural flavonoid liquiritigenin reportedly inhibits invasiveness of breast cancer cells, but its specific role and mechanism remain largely unclear. In this study, cells from the triple negative breast cancer lines MDA-MB-231 and BT549 were incubated with different concentrations of liquiritigenin. The results indicated that low concentrations had no significant cytotoxic effect, whereas high concentrations decreased viability of both MDA-MB-231 and BT549 cells. Liquiritigenin treatment also resulted in increased apoptosis and enhanced Caspase3 activity. After liquiritigenin treatment, we observed decreased invasive and migratory capacities of cells, as well as upregulated E-cadherin and downregulated N-cadherin, vimentin, and MMP9. Interestingly, liquiritigenin increased the mRNA and protein expression of breast cancer 1 (BRCA1). It also increased p21 and growth arrest and DNA-damage-inducible 45 alpha (GADD45A) levels, accompanied by decreased cellular DNA methyltransferase (DNMT) activity and downregulation of DNMT1, DNMT3a, and DNMT3b. These findings suggest that liquiritigenin can inhibit malignant behavior of triple negative breast cancer cells by inhibiting DNMT activity and increasing BRCA1 expression and its transcriptional activity. Liquiritigenin thus may be a promising candidate for the treatment of breast cancer.