Effects of Bisphenols on RACK1 Expression and Their Immunological Implications in THP-1 Cells

Erica Buoso; Maša Kenda; Mirco Masi; Pasquale Linciano; Valentina Galbiati; Marco Racchi; Marija Sollner Dolenc; Emanuela Corsini

doi:10.3389/fphar.2021.743991

Effects of Bisphenols on RACK1 Expression and Their Immunological Implications in THP-1 Cells

Front Pharmacol. 2021 Sep 21:12:743991. doi: 10.3389/fphar.2021.743991. eCollection 2021.

Authors

Erica Buoso¹, Maša Kenda², Mirco Masi^{1

3}, Pasquale Linciano¹, Valentina Galbiati⁴, Marco Racchi¹, Marija Sollner Dolenc², Emanuela Corsini⁴

Affiliations

¹ Università Degli Studi di Pavia, Dipartimento di Scienze del Farmaco, Pavia, Italy.
² University of Ljubljana, Faculty of Pharmacy, Ljubljana, Slovenia.
³ Scuola Universitaria Superiore IUSS, Pavia, Italy.
⁴ Università Degli Studi di Milano, Laboratory of Toxicology, Dipartimento di Scienze Politiche ed Ambientali, Milan, Italy.

Abstract

Receptor for activated C kinase 1 (RACK1) has an important role in immune activation, and is regulated through a balance between glucocorticoid and androgen levels. We have previously demonstrated that RACK1 expression can serve as a marker for evaluation of immunotoxic profiles of hormone-active substances, such as endocrine-disrupting chemicals (EDCs). In this study, we investigated the effects of three bisphenols (BPA, BPAF, BPS) on RACK1 expression and on the innate immune responses in the THP-1 human promyelocytic cell line, a validated model for this investigation. BPA and BPAF reduced RACK1 promoter transcriptional activity, mRNA expression, and protein levels. However, BPS had the opposite effect. As expected, these results on RACK1 were paralleled by lipopolysaccharide (LPS)-induced interleukin-8 (IL-8) and tumor necrosis factor-α (TNFα) production. Since BPA and BPAF induced RACK1 expression in the presence of glucocorticoid receptor (GR) antagonist mifepristone, a role of G-protein-coupled estrogen receptor (GPER) has been considered due to their known estrogenic profile. Therefore, additional molecular effects of BPA and BPAF were unmasked after treatment with different inhibitors of well-known pivotal players of GPER-mediated signaling. BPA exerted its effects on RACK1 via NF-κB, as shown using the NF-κB inhibitor BAY11-7085 and NF-κB-specific luciferase reporter assay. Conversely, BPAF induced RACK1 up-regulation via androgen receptor (AR) activation, as confirmed by treatment with AR antagonist flutamide. Indeed, a biased agonism profile for BPA and BPAF for GPER was suggested based on their different binding modes revealed by our molecular docking. Altogether, our data suggest that RACK1 could represent an important target of EDCs and serves as a screening tool for their immunotoxic potential. Furthermore, RACK1 can be exploited to unmask multiple molecular interactions of hormone-active substances to better dissect out their mechanisms of action.

Keywords: AR; GPER; RACK1; bisphenols; endocrine-disrupting chemicals (EDCs); hormone effects; immune function; immunotoxicity.