MON-038 The Effects of Isoliquiritigenin (ISL) on the Expression of Estrogen Receptor and Tumor Suppressor Genes BRCA-1 and P53 in Breast Cancer Cells

Abstract

Naturally sourced treatments are increasingly sought for health issues including breast cancer. Isoliquiritigenin (ISL), a phenolic flavonoid in licorice root, has recently received attention in public and scientific communities for its antioxidant, anti-inflammatory and tumor suppressive effects. Standard medical practice now includes determining receptor status of breast cancers and estimates show that 55-65% of women with a BRCA1 gene mutation will develop hereditary breast cancer, therefore finding treatment options for receptor-positive patients is critically important. This study examined the effects of ISL, alone and in combination with hormones and anti-hormones, on ERα, p53, and BRCA1 expression in MCF-7 and T-47D breast cancer cells by utilizing western blot analyses, cellular viability assays, confocal microscopy, apoptosis assay and RT-qPCR analyses. To ensure treatment conditions without the presence of endogenous steroids or growth factors, cells were cultured in a medium containing 5% charcoal-stripped fetal bovine serum (FBS) for a duration of 6 days. For western blot analyses, cells were treated with various concentrations of ISL ranging from 5-100 µM for 24 hours. Compared to the control, a concentration dependent decrease of ERα (85%) and BRCA1 (60%) was noted in both cell lines, while the expression of p53 seemed to be altered based on the specific breast cancer cell lines. In our hormone studies, we used the optimal concentration of 50μM ISL alone and in combination with hormones and anti-hormones. After 24-hour treatment of ISL, E2, and E2 with ISL on the breast cancer, cells showed a decrease in ERα and BRCA-1 expression compared to the control. Combination treatment of ISL with anti-hormone ICI revealed a significant down regulation (approximately 65-85%) of ERα, BRCA-1, and p53 in T-47D cells. The same treatment conditions in MCF-7 cells revealed a significant down regulation of ERα and BRCA-1, while p53 expression was up regulated. Image cytometric analysis with propidium iodide staining was performed to examine the effects that ISL has on cellular viability in T-47D and MCF-7 cells. Cells treated for 6 days with 50 μM ISL concentration with hormone and anti-hormones displayed a decrease in cell proliferation compared to the control in both cell lines. RT-qPCR studies revealed a transcriptional expression of ESR1 and BRCA-1 mRNA levels that correlate with the translational data obtained via western blot analyses. Cytolocalization studies are in progress and apoptosis assays are currently being performed to determine the mechanism(s) of cell death. Our studies offer an intriguing direction to explore the molecular mechanisms of ISL on the steroid receptors and tumor suppressor gene in breast cancer cells.