Investigation of the Effects of Estradiol and Testosterone on the Expression Levels of Genes Involved in Reverse Cholesterol Transport in Palmitate- and Oleate-Treated HepG2 Cells

Introduction The prevalence of non-alcoholic fatty liver disease (NAFLD) is lower in premenopausal women than men but increases after menopause due to estrogen decline. This study investigates the role of sex hormones, β-estradiol and testosterone, in the expression of reverse cholesterol transport (RCT)-related genes in HepG2 cells loaded with palmitate and a palmitate/oleate mixture. Methods The effective concentrations of palmitate and oleate in HepG2 cells were determined by the MTT assay, resulting in the development of two models: The P model (palmitate only) and the P/O model (palmitate/oleate mixture). Cells were treated with β-estradiol and testosterone, lipid droplet content, cholesterol, triglycerides, and gene expression (ABCA1, ABCG1, SR-B1, APOA1, LXR-α) were measured. Results The results demonstrated that both testosterone and β-estradiol significantly reduced LD content in HepG2 cells, with a synergistic effect observed when the hormones were combined, particularly in the P/O model. In the P/O model, sex hormones reduced triglyceride content in a dose-dependent manner, with β-estradiol exerting a stronger effect at higher doses while simultaneously increasing cholesterol levels, particularly at lower doses of β-estradiol and higher doses of testosterone. Both testosterone and β-estradiol modulated the expression of RCT-related genes in a dose-dependent manner, with β-estradiol generally showing stronger effects, particularly in the P/O model. However, combined hormone treatment did not significantly differ from individual hormone treatments in most cases. Conclusion Testosterone and β-estradiol modulate lipid metabolism and RCT-related gene expression in HepG2 cells, with β-estradiol showing stronger effects, especially in the P/O model.