Abstract
Bisphenol A (BPA) has been shown to exhibit various toxic effects, including the induction of reproductive disorders. Generally, BPA is converted to conjugated metabolites, leading to bio-inactivation. On the other hand, the toxicity of conjugated metabolites is not fully understood. Notably, the placenta develops the sulfate-sulfatase pathway, which transports and reactivates sulfated steroids. Therefore, we investigated the potential adverse effects of the BPA-sulfate conjugate (BPA-S) on human placenta-derived BeWo cytotrophoblasts. In the present study, high-concentration BPA-S (100 μM) induced significant inhibition of BeWo growth, with effects similar to those seen with unconjugated BPA (100 μM and 100 nM). This growth inhibition was restored by treatment of the cells with an inhibitor of the organic anion-transporting peptides (OATPs) (bromosulphophthalein) or with a sulfatase (STS) inhibitor (STX64). BeWo exhibits expression of the genes encoding OATP1A2 and OATP4A1 as known sulfated steroid transporters and STS, suggesting that BPA-S suppresses cell growth activity via the sulfate-sulfatase pathway. In addition, cell cycle analysis revealed that BPA-S (100 μM) increased the fraction of cytotrophoblasts in the G2/M phases and significantly decreased the accumulation of the transcript encoding Aurora kinase A (AURKA), which is a critical regulator of cellular division. These results suggested that BPA-S triggers cell cycle arrest and inhibits proliferation of BeWo cytotrophoblasts by decreased AURKA, an effect that is mediated by the sulfate-sulfatase pathway. Overall, these findings provide insights into the reactivation of sulfated endocrine-disrupting chemicals and subsequent adverse effects.