Figure 4.

Effects of NAC on cholesterol levels and lipogenesis‐related genes in hypoxanthine‐ or H₂O₂‐treated HepG2 cells. Cells were treated with hypoxanthine (1 mM) or H₂O₂ (500 μM) for 2 hrs (for Amplex red assay) or 24 hrs (for cholesterol quantification) following a 2 hrs pre‐incubation with 5 mM NAC. (A) The levels of H₂O₂ were determined by the Amplex red assay and total cholesterol and cholesteryl ester levels were assayed in cell lysates. (B) Cells were treated with 1 mM hypoxanthine for 24 hrs, following a 2 hrs pre‐incubation with 5 mM NAC. APOE,ABCA1,HMGCR and LDLR mRNA levels were determined by real‐time RT‐PCR. (C) APOE, ABCA1, HMGCR, LDLR and β‐actin protein levels were measured by western blot analysis. (D) Cells were treated with 500 μM H₂O₂ for 24 hrs, following a 2 hrs pre‐incubation with 5 mM NAC. APOE,ABCA1,HMGCR and LDLR mRNA levels were determined by real‐time RT‐PCR. (E) APOE, ABCA1, HMGCR, LDLR and β‐actin protein levels were measured by western blot analysis. Relative protein expression was determined using densitometry. Data are presented as the mean ± S.E.M. *P < 0.05, **P < 0.01, ***P < 0.001 versus control (Ctrl). #P < 0.05, ##P < 0.01, ###P < 0.001 versus hypoxanthine (Hx). AU: arbitrary units.