PMON13 The Effects of Perfluorooctanesulfonic Acid (PFOS) on the Expression of Estrogen Receptor Alpha (ERα) and Tumor Suppressor Gene BRCA1 in Breast Cancer Cells

Perfluoroctanesulfonic Acid (PFOS) is a perfluorinated chemical (PFC) and endocrine-disrupting compound (EDC) found in fire-extinguishing foams, food packing, and commonly used household products such as nonstick cookware and cleaning products. PFOS is also an environmental toxicant that has polluted air, soil, and water in past years. Few studies have suggested PFOS may cause endocrine-disrupting effects, therefore it is critical to explore the effects of PFOS on breast cancer cells. This study examined the estrogenic-like effects of PFOS, alone and in combination with hormones and antihormones, on the expression of ERα and BRCA1 in T-47D and MCF-7 breast cancer cell lines by utilizing western blot analyses, cellular viability assays, confocal microscopy, apoptosis assay and RT-qPCR analyses. The cells were cultured with 5% charcoal-stripped fetal bovine serum (FBS) for six days to deplete endogenous steroids or growth factors. In the concentration-dependency study, cells were treated with various concentrations of PFOS (300µM-800µM) for 24 hours. Western blot analysis revealed alterations in the expression of ERα and BRCA1 related with these varying concentrations of PFOS (300 µM-800µM). In comparison to the control, a concentration-dependent decrease of ERα expression levels were seen in both cell lines. A concentration-dependent increase of BRCA1 was seen in both cells. Western blot analysis revealed the optimal concentration of PFOS to be 700 µM in cells, which exhibited the maximal estrogenic-like effect. To further examine the effects of PFOS on breast cancer cells, the optimal concentration (700 µM PFOS) was then used alone and in combination with hormones and anti-hormones in T-47D cells. Treatment with PFOS, E(2)and the combination of PFOS and E(2) for 24 hours showed a significant down-regulation of ERα in T-47D cells when compared to the control. Treatment of PFOS with antiestrogen ICI revealed a significant down-regulation of ERα (approximately 50%) in T-47D cells. Image cytometric analysis with propidium iodide staining was utilized to examine the effects of PFOS on cellular viability in T-47D cells. PFOS alone and in combination with E2 revealed an increase in cellular proliferation compared to the control in T-47D cells and these effects were sensitive to the presence of antiestrogens. 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 experiments and effects of PFOS with hormones and antihormones on MCF-7 cells studies are in progress. Our studies provide exciting leads to clearly delineate the molecular mechanisms of PFOS as an EDC on the steroid receptors and tumor suppressor gene in breast cancer cells. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.