Morpho-Functional Effects of Nonylphenol–Steroid Hormone Co-Exposure on Human Prostate PNT1A Cells

Nonylphenol (NP) is a chemical compound belonging to the class of alkylphenols (APs), known for its widespread environmental distribution and endocrine-disrupting properties. It is commonly used in the production of detergents, pesticides, and plastic materials and, owing to these properties, it can accumulate in both aquatic and terrestrial ecosystems. As a xenoestrogenic compound, NP can bind steroid receptors, including estrogen receptors (ERs), thereby activating ER-dependent pathways. In this work, we investigated the effects of NP alone and in combination with the endogenous hormones 17β-oestradiol (E2) and/or testosterone (T) on a human non-tumoral prostate cell line (PNT1A). Cell viability and migration assays, together with analysis of ER expression and localization, were carried out to assess the xenoestrogenic activity of NP, particularly in the presence of E2 and T. Our results showed that NP retained its endocrine-disrupting features in the mixtures, positively affecting cell viability, except for the NP+E2 mixture, in which cell viability did not significantly differ from control, suggesting an antagonistic interaction between NP and E2. The mixtures also interfered with steroid receptor dynamics, affecting receptor expression and delaying receptor localization and activation kinetics. Moreover, all mixtures negatively affected cell migration compared with treatment with endogenous hormones alone. In conclusion, our results demonstrate that NP retains its xenoestrogenic behavior in mixture, inducing a significant alteration in prostate cell homeostasis.