The Detrimental Impact of Bisphenol S (BPS) on Trophoblastic Cells and the Ishikawa Cell Lines: An In Vitro Model of Cytotoxic Effect and Molecular Interactions

<b>Background/Objectives</b>: Bisphenols (BPs) and especially bisphenol S (BPS), an analog of bisphenol A (BPA), are widely used and induce oxidative stress, resulting in the inhibition of cell proliferation and induction of apoptosis which all are crucial for reproduction, the progression of pregnancy, and fertility. The present study integrates trophoblastic cells as an in vitro model to provide evidence and investigate the molecular interactions regarding placenta-related pregnancy complications after cytotoxic exposure to BPS. <b>Methods</b>: Human endometrial epithelial adenocarcinoma Ishikawa cell lines and trophoblastic cells were cultured. Cells obtained from the cultures were divided into plates and incubated for 24 h with different concentrations of bisphenol S (BPS). Cell viability was measured using the Countess Automated Cell Counter and the viability of Ishikawa cells was assessed after 48 h and for trophoblasts after 24 h. The effect of siRNA on <i>NANOG</i> expression was evaluated using qRT-PCR. Quantification of DNMT and NANOG was performed by qPCR and the G6PD gene was used as an internal control. <b>Results</b>: Real-time PCR results showed that the expression of the <i>DNMT1</i> gene varies depending on the concentration of BPS in trophoblastic cells. In Ishikawa cell lines, real-time PCR results showed that <i>DNMT1</i> gene expression was higher due to cell increase, but the measured fold change did not differ significantly. Data analysis indicated a statistically significant difference between CpDNMT1 in trophoblasts with and without BPS, where higher values were observed in the case of BPS presence (<i>p</i> = 0.019). The largest difference was observed between CpDNMT1 trophoblasts without BPS and CpDNMT1 Ishikawa with BPS (<i>p</i> < 0.001). Silencing the <i>NANOG</i> gene resulted in a reduced expression of <i>DNMT1</i>, while the <i>G6PD</i> gene was still detected. <b>Conclusions</b>: The results of this study highlight the cytotoxic effects of BPS and consequently its effect on trophoblast viability. The results of NANOG-DNMT1 gene expression related to BPS exposure reinforces our understanding of EDC-induced placental dysfunction.