Molecular insights underlying the adverse effects of bisphenol A on gonadal somatic cells' steroidogenic activity

Abstract

Bisphenol A (BPA) exposure may impair gonadal steroidogenesis, although the underlying mechanism is not well known. Hereby, we assessed BPA action on human primary granulosa (hGC) and mouse Leydig cells (BLTK-1) proliferation, cytotoxicity, hormone secretion, and steroidogenic enzyme/receptor gene profile. hGC and BLTK-1 cells were stimulated with increasing concentrations of BPA (10^-12 M to 10^-4 M for cell proliferation assay, 10^-8 M to 10^-4 M for LDH-cytotoxicity assay, and 10^-9 M to 10^-5 M for hormone secretion and genes expression analysis). BPA at low concentrations (pM - nM) did not affect cell proliferation in either cell type, although was toxic at higher (µM) concentrations. BPA stimulation at low nM concentrations decreased the production of estradiol (E₂) and testosterone (T) in BLTK-1, E_2, and progesterone in hGCs. BPA down-regulated Star, Cyp11a1, and Hsd17b3, but up-regulated Cyp19a1, Esr1, Esr2, and Gpr30 expression in BLTK-1 cells. In hGC, BPA down-regulated STAR, CYP19A1, PGRMC1, and PAQR7 but up-regulated ESR2 expression. Estrogen receptor degrader fulvestrant (FULV) attenuated BPA inhibition of hormone production in both cell lines. FULV also blocked the BPA-induced Gpr30 up-regulation in BLTK-1 cells, whereas in hGC, failed to reverse the down-regulation of PGRMC1, STAR, and CYP19A1. Our findings provide novel mechanistic insights into environmentally-relevant doses of BPA action through both nuclear estrogen receptor-dependent and independent mechanisms affecting cultured granulosa and Leydig cell steroidogenesis.

Keywords: Bisphenol A; Gonadal somatic cells; Steroidogenesis.