Effect of probucol on expression of Niemann-Pick C1 protein and cholesterol efflux in RAW264.7 macrophages

Abstract

Objective To observe the effects of the serum from the mice pretreated with probucol on cellular cholesterol efflux and the impact of different concentrations of probucol on the expression of Niemann-Pick C1 protein (NPC1) in macrophages. Methods Sixteen male C57BL/6 mice were randomly divided into two groups and fed on either vehicle or 0.5% w/w probucol for 4 weeks respectively. The serum was collected and the lipids profile was detected by enzymatic method. Raw264.7 macrophages were loaded with acetylated low-density lipoprotein and labeled with 3H-cholesterol, then the efflux of cholesterol was quantitated with the serum mentioned above as the acceptors. Reverse transcription polymerase chain reaction and Western blotting were used to evaluate the mRNA and protein expression of NPC1. Results More cholesterol efflux from the cultured macrophages was mediated by the serum from the mice treated with probucol for 4 weeks than those from the control mice [(36.30±0.02)% vs. (21.20±0.04)%, P=0.003]. Different concentrations of probucol (0, 10, 20, 50, and 100 μmol/L) dose-dependently upregulated the mRNA [(0.75±0.03), (0.94±0.04), (1.18±0.06), (1.22±0.03) vs. (0.52±0.04), P=0.036, P=0.021, P=0.045, P=0.037] and protein [(0.68±0.05), (0.85±0.02), (1.16±0.04), (1.19±0.05) vs. (0.49±0.02), P=0.011, P=0.040, P=0.034, P=0.015] expression of NPC1 in macrophages, and promoted cholesterol efflux [(46.10±0.03)%, (51.40±0.05)%, (55.30±0.06)%, (57.80±0.08)% vs. (36.30±0.02)%]. Conclusion The serum from the mice treated with probucol markedly promoted cholesterol efflux from the cultured macrophages. Probucol promoted efflux from the macrophages dose-dependently probably through increasing the expression of NPC1. Key words: Probucol; Niemann-Pick C1 protein; Macrophages; Cholesterol