Comparative ChIP-Seq Analysis of ERα Binding Induced by Estradiol, Zearalenone, and Bisphenol A in Human Ovarian Cells

Xenoestrogens are synthetic or natural compounds that mimic the effect of endogenous estrogens by binding to estrogen receptors (ERs). Human exposure to xenoestrogens is increasing globally, raising substantial concerns regarding their endocrine-disrupting effects. Here, we investigated the ERα-mediated genomic and transcriptional response of human ovarian cells following exposure to estradiol (E2), zearalenone (ZEA), and bisphenol A (BPA) using ChIP-seq integrated with transcriptomic analysis. Our results demonstrate that the ERα-dependent response induced by ZEA closely resembles that of E2, whereas BPA elicits a markedly attenuated response. ERα signal intensity was higher in cells treated with E2 or ZEA than in cells treated with BPA, indicating reduced ERα occupancy in response to BPA exposure. We identified 641 genomic regions that were occupied by ERα after any treatment, defining a core set of shared binding sites. Integration with mRNA-seq datasets revealed 162 ERα-binding sites located within ±50 kb of the transcription start sites of 109 upregulated genes. Among these, 28 genes were induced across all treatments, constituting a core estrogen-responsive gene set in human ovarian cells. RT-qPCR validation of six representative genes (GREB1, RASGRP1, CISH, RBBP8, KCNF1, and LONRF2) confirmed stronger and sustained transcriptional induction following E2 and ZEA exposure than following BPA exposure; this induction was inhibited by the ERα antagonist MPP. Our findings suggest that BPA has a lower capacity to activate ERα chromatin binding and downstream transcriptional programs, affecting primarily high-affinity estrogen-responsive loci in human ovarian cells.