ABSTRACT
Aim To explore the effects of niacin on LDL-C uptake and metabolism in HepG2 cells,and to clarify the functions of niacin in lipid-lowering and slo-wing the atherosclerosis process,thus to provide a sci-entific basis for niacin as a lipid-lowering drug in clini-cal development.Methods Oil red O staining was used to observe HepG2 cells after lipid uptake.Enzy-matic method was used to determine the content of in-tracellular free cholesterol (FC)and total cholesterol (TC).The LDLR levels on the surface of cell mem-brane were detected by immunofluorescence flow cy-tometer.The mRNA and protein expressions of LDLR, SREBP2 and PCSK9 were analyzed by qPCR and Western blot.Results The results of oil red O staining showed that the rate of oil red O-positive cells and the number of red lipid droplets were significantly in-creased in niacin group than control group.Niacin sig-nificantly increased the levels of TC and FC in HepG2 cells(P <0.05 ).What’s more,niacin significantly upregulated the expression of LDLR and significantly downregulated the protein expression of PCSK9,while it had no effect on the expression of SREBP2.Conclu-sion Niacin accelerates LDL-C uptake probably via downregulating the expression of PCSK9 and reducing the degradation of LDLR protein in HepG2 cells.