SAT-462 Estrogen-like Effects of Perfluorooctanoic Acid (PFOA) on Estrogen Receptor (ERα) and Tumor Suppressor Gene (BRCA1) in Breast Cancer Cells

Abstract A. Zanib: None. S. Pfiffner: None. E. Hallman: None. N. Prudhomme: None. R. Yaldo: None. J. Koujane: None. K. Farrar: None. S. Dinda: None. Perfluorooctanoic Acid (PFOA), a perfluoroalkyl substance (PFAS), is commonly found in everyday items such as non-stick cookware, cosmetics, and upholstery. This synthetic compound is resistant to environmental degradation and is frequently detected in drinking water and living organisms. Due to its widespread usage and bioaccumulation, numerous concerns are associated with PFOA regarding its biological effects. Prior studies have indicated that the PFAS functions as an endocrine-disrupting compound. Therefore, it is imperative to investigate the potential associations of PFOA with breast cancer, the most frequently diagnosed malignancy worldwide. Our study examined the effects of PFOA, both alone and in combination with hormones and antihormones, on the expression of ERα and BRCA1 in T-47D and MCF-7 cell lines, utilizing western blot analyses, cellular viability assays, confocal microscopy, and RT-qPCR. Cells were cultured with 5% dextran-coated, charcoal-treated fetal bovine serum (DCC-FBS) for a duration of six days to eliminate endogenous steroids and effectors. In studies focusing on the concentration effects of the compound, cells were subjected to varying concentrations of PFOA (ranging from 100nM to 500μM) for a duration of 24 hours. Western blot analyses detected alterations of ERα and BRCA1 expression at various concentrations. Compared to the control, both cell lines exhibited a concentration-dependent downregulation of ERα expression, along with a concentration-dependent upregulation of BRCA1 expression. Moreover, an optimal concentration, mimicking effects similar to 17-β-estradiol (E2), was identified to be 250 µM for both cell lines. This optimal concentration was utilized in the subsequent hormone studies, where cells were subjected to treatment with PFOA, both independently and in conjunction with hormones and antihormones. Treatment with E2 and the combination of PFOA + E2 resulted in a significant decrease in the expression of ERα in both cell lines. With the exception of TAM, combination treatments involving antiestrogens (PFOA + ICI and PFOA + BZA) demonstrated downregulation of ERα expression. This effect was more sensitive in the combination treatment with ICI as compared to BZA. Cellular viability with the propidium iodine stain was utilized, revealing that PFOA and PFOA + E2 significantly increased cellular proliferation in MCF-7 cells as compared to the control. Cellular viability in T-47D, cytolocalization, and RT-qPCR experiments are currently in progress to further elucidate these findings. The results of this research offer interesting insights into the existing literature on PFOAs, enhancing understanding of the interplay between this compound and its impact on steroid receptors and tumor suppressor genes in breast cancer. Saturday, June 1, 2024