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Objectives: To investigate the cytotoxic effects of lysophosphatidylcholine (lysoPC), an active component of oxidized low-density lipoproteins (LDL), on vascular smooth muscle cells (VSMCs). Methods: VSMCs were derived from rat aorta. Cell death was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, lactic dehydrogenase (LDH) assay, and DNA fragmentation assay. Apoptosis was quantified by propidium iodide staining and fluorescent activated cell sorting (FACS) analysis, and intracellular free radical production was determined using 2’,7’-dichlorofluorescin diacetate (DCF-DA). In addition, the changes in caspases, bcl-2 and bax proteins were evaluated by western blot analysis. Results: LysoPC over 25 ?M induced more than 50% of the cell death at 10 hours on MTT assay with no change in the level of LDH. The DNA ladder pattern showed that cell death induced by lysoPC was caused by apoptosis, which was associated with increased free radical production. Vitamin E, a potent antioxidant and caffeic acid phenylethyl ester (CAPE), an inhibitor of nuclear factor-kappaB (NF-kB), blocked apoptosis. The casepase-3 precursor decreased and the active form of caspase-8 increased. Total bcl-2 and bax proteins did not change with lysoPC treatment, but translocation of bax from cytosole to the mitochondria membrane was observed. Conclusion: LysoPC induces apoptosis in VSMCs via an oxidant mechanism, dependent on NF-kB.
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