Hexabromocyclododecane facilitates FSH activation of ERK1/2 and AKT through epidermal growth factor receptor in rat granulosa cells

• Published in: Archives of toxicology 2014-02, Vol.88 (2), p.345-354
• Main Authors: Fa, Svetlana, Samardzija, Dragana, Odzic, Ljubica, Pogrmic-Majkic, Kristina, Kaisarevic, Sonja, Kovacevic, Radmila, Andric, Nebojsa
• Format: Article
• Language: English
• Subjects: Animals; Biomedical and Life Sciences; Biomedicine; Butadienes - pharmacology; Cells; Cells, Cultured; Environmental Health; Female; Females; Follicle Stimulating Hormone - pharmacology; Gene Expression Regulation - drug effects; Granulosa Cells - drug effects; Granulosa Cells - metabolism; Hydrocarbons, Brominated - toxicity; MAP Kinase Signaling System - drug effects; Molecular Toxicology; Neurons; Nitriles - pharmacology; Occupational Medicine/Industrial Medicine; Pharmacology/Toxicology; Phosphorylation - drug effects; Proto-Oncogene Proteins c-akt - metabolism; Quinazolines; Rats; Rats, Wistar; Receptor, Epidermal Growth Factor - antagonists & inhibitors; Receptor, Epidermal Growth Factor - metabolism; Receptors, LH - genetics; Reproductive system; Rodents; Toxicity; Toxicity Tests - methods; Tyrphostins
• ISSN: 0340-5761; 1432-0738
• DOI: 10.1007/s00204-013-1133-2

The toxicity of hexabromocyclododecane (HBCDD) has been extensively studied; however, the mechanism and the effects of HBCDD on female reproductive system have been less frequently reported. In this study, we exposed rat granulosa cells to HBCDD during in vitro follicle-stimulating hormone (FSH)-driven cell proliferation and differentiation. Here, we show that HBCDD affects the FSH-driven signal transduction and ovulatory competence of granulosa cells. We found that HBCDD over-activates the FSH-stimulated extracellular-regulated kinase 1/2 (ERK1/2) and protein kinase B (PKB, also known as AKT). Inactivation of the epidermal growth factor receptor (EGFR) kinase activity with AG1478 and the mitogen-regulated kinase activity with U0126 completely prevented ERK1/2 activation in the FSH-stimulated and HBCDD-exposed granulosa cells. Moreover, AG1478 restored the HBCDD-induced AKT activation to the level observed in the FSH-stimulated cells. Western blot shows that HBCDD potentiates FSH-stimulated EGFR phosphorylation in granulosa cells. Real-time PCR demonstrates that HBCDD decreases the FSH-induced luteinizing hormone receptor ( Lhr ) expression. Inadequate level of LHR in the HBCDD-exposed granulosa cells prevented human chorionic gonadotropin in stimulating expression of the ovulatory genes such as amphiregulin ( Areg ), epiregulin ( Ereg ), and progesterone receptor ( Pgr ). Addition of U0126 and AG1478 restored Lhr level in the FSH-stimulated and HBCDD-exposed granulosa cells. These results indicate a direct effect of HBCDD on EGFR activation, resulting in over-activation of ERK1/2 and AKT signal transduction pathways in the FSH-treated cells. Increased activity of the EGFR-ERK1/2 pathway above physiological level prevents sufficient acquisition of LHR in proliferating granulosa cells, thus compromising ovulation.