Abstract 423: Imatinib Promotes Reverse Cholesterol Transport And Elevates Sr-bi

Abstract

Dyslipidemia is a cardiovascular risk factor for coronary artery disease and atherosclerosis that is characterized by elevated serum cholesterol and lipid levels. Although high-density lipoprotein-associated cholesterol (HDL-C) is associated with reduced risk of cardiovascular events, targeted therapy to increase HDL-C levels have been unsuccessful in altering outcomes of associated atherosclerotic disease. Single nucleotide polymorphisms in SCARB1 , the gene that encodes HDL receptor Scavenger Receptor B1 (SR-BI), are associated with dyslipidemia and atherosclerotic cardiovascular disease. We were the first to identify inherited mutations in SCARB1 that segregate with disease in a family with severe coronary artery disease and dyslipidemia, including elevated HDL. Our findings suggest that HDL function (vs. HDL-C concentration) may be a promising target for cholesterol-based therapy. Here, we performed an unbiased high throughput drug screen with 788 FDA-approved compounds, using HepG2 cells to measure endogenous HDL binding. We identified five compounds that significantly increased endogenous HDL binding: imatinib, trimethoprim, eszopiclone, clemastine, and mepenzolate, of which, imatinib was the only compound to increase SR-BI expression. Imatinib is a tyrosine kinase inhibitor that is a chemotherapeutic agent designed to treat individuals with chronic myeloid leukemia. Limited clinical evidence suggests a reduction in total cholesterol with 400mg/day imatinib. Additionally, imatinib treatment (150mg/kg) in mouse models of atherosclerosis reduces total cholesterol. Yet, no data is available on the effects of imatinib on HDL and reverse cholesterol transport. We have found that imatinib promotes HDL binding and SR-BI expression in vitro . Furthermore, in wildtype C57Bl/6 mice on a high fat, high cholesterol diet, imatinib treatment (50mg/kg) was sufficient to decrease plasma total cholesterol, HDL-C and triglyceride levels and elevate hepatic SR-BI expression. In summary, our data supports the exploration of imatinib-mediated SR-BI regulation, HDL metabolism, and RCT pathway to identify new therapeutic targets for dyslipidemia.