Cholesterol Esterification as a Mediator of Proliferation of Vascular Smooth Muscle Cells and Peripheral Blood Mononuclear Cells during Atherogenesis

Abstract Background/Aims: We determined growth rates, cholesterol esterification and mRNA levels for caveolin-1 (Cav-1), neutral cholesterol esters hydrolase (n-CEH) and ATP-binding cassette transporter (ABCA-1), in quiescent and growth-stimulated peripheral blood mononuclear cells (PBMCs) and intimal vascular smooth muscle cells (VSMCs) from blood and primary atherosclerotic plaques, respectively. These cells were cultured in the presence or absence of the mTOR inhibitor 40-O-(2-hydroxyethyl) rapamycin (RAD). Methods: The rate of cell proliferation was determined by 3H-thymidine incorporation into DNA and that of lipid metabolism by utilizing 14C-acetate and 14C-oleate as precursors. Lipid deposit in the vascular cells was evaluated by Oil Red O staining and lipid mass by thin layer chromatography-linked enzymatic assay. Results: Growth stimulation of PBMCs and VSMCs caused a rapid increase in intracellular cholesterol esterification and an accumulation of cholesterol esters (CEs) accompanied by a reduction of free cholesterol (FC) and Cav-1, ABCA-1 and n-CEH mRNAs. RAD reduced intracellular lipid accumulation in growth-stimulated cells and also increased expression of Cav-1, n-CEH and ABCA-1 genes. Conclusion: Collectively, these data provide evidence that the determination of CEs in PBMCs may be an easy prescreening test to identify subjects at risk for vascular proliferative disease and that FC, CE, Cav-1, n-CEH and ABCA-1 may be suitable targets for antiproliferative therapies.