Endocrine disrupting chemicals (EDCs) are a pervasive and growing threat to human health. Current in vitro screening tests hormone receptors in isolation using transcriptional activation as the sole readout, as in the CALUX assay (1,2). However, tissues most vulnerable to EDC-mediated disease, such as endometrium, breast, and prostate (3–5), co-express hormone receptors such as the estrogen receptor (ER), androgen receptor (AR), and progesterone receptor (PR), which signal through extensive crosstalk (6). Whether this crosstalk changes the impacts of EDCs when receptors are compared in a controlled single- versus multi-receptor system, has not been established. If it does, current EDC screening may systematically misclassify risk. We aim to determine whether multi-receptor context changes EDC detection.

We engineered reporter cell lines with individual or combined receptors to characterise functions. We are screening a panel of established EDCs spanning the three receptors, followed by defined EDC mixtures, across matched single- and multi-receptor lines.

We will determine whether nuclear translocation and reporter transactivation dissociate under EDC treatment, and whether this divergence differs between single- and multi-receptor cells, quantified as the nuclear-to-cytoplasmic ratio compared to transactivation for each compound. Second, we will examine whether EDCs and defined EDC mixtures produce responses in multi-receptor cells that are not predicted from single-receptor, single-compound data.

If translocation and transactivation diverge, transactivation-only assays would report an incomplete picture of receptor disruption. If responses differ between single- and multi-receptor cells, single-receptor screening would misclassify EDCs in the multi-receptor tissues they target and misjudge the non-additive mixtures that real exposures consist of. Either result would indicate that biologically representative, multi-receptor screening is needed to protect human reproductive health.