Identification of two antagonists of the scavenger receptor CD36 using a high-throughput screening model

CD36, a class B scavenger receptor, is an integral membrane protein that mediates the endocytosis of modified lipoproteins. The functions of CD36 are complex and have been associated with atherosclerosis. In the current study, we developed a high-throughput screening (HTS) assay to identify small molecule antagonists by expressing human CD36 using a Bac-to-Bac baculovirus expression system in Spodoptera frugiperda (Sf9) cells. Uptake of 1,1'-dioctadecy1-3,3,3',3'-tetramethylindocarbocyanine perchloratelabeled acetylated low-density lipoprotein (Dil-AcLDL) revealed that the IC50 values for the CD36 ligands oxidatively modified LDL (Ox-LDL), Ac-LDL, and high-density lipoprotein (HDL) were 0.039, 0.019, and 0.010 mu g/ml, respectively. Using the HTS assay, two novel compounds, 2016481B and 2038751B, were found to inhibit Dil-AcLDL uptake in insect cells and exhibited IC50 values of 17.4 and 23.7 mu M, respectively. These two novel compounds also inhibited Dil-AcLDL uptake in cultured Chinese hamster ovary (CHO) cells permanently expressing human CD36. Furthermore, these two compounds inhibited lipid accumulation in RAW 264.7 murine macrophage cells in foam cell assays. This FITS assay represents a potential method for identifying more effective macrophage scavenger receptor antagonists, which may serve as starting points for the development of novel anti-atherosclerotic agents. (C) 2010 Elsevier Inc. All rights reserved.