Curcumin inhibits cholesterol uptake in Caco-2 cells by down-regulation of NPC1L1 expression.
Curcumin inhibits cholesterol uptake in Caco-2 cells by down-regulation of NPC1L1 expression.
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DOI：
10.1186/1476-511x-9-40
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发表时间：
2010-04-19
影响因子：
4.5
通讯作者：
Duan RD
中科院分区：
文献类型：
--
作者：
Feng D;Ohlsson L;Duan RD
姜黄素是一种多酚，也是香料姜黄的主要姜黄素之一。其抗氧化、抗癌和抗炎作用已被深入研究。先前的体内研究表明，姜黄素的施用也降低了血液中的胆固醇水平，并且该作用被认为与LDL受体的上调有关。然而，由于血浆胆固醇水平也受到肠道中胆固醇摄取的影响，而肠道中胆固醇的摄取是由特异性转运蛋白Niemann-Pick Cl-样1（NPC 1 L1）蛋白介导的，因此本研究旨在研究姜黄素是否影响肠道Caco-2细胞中胆固醇的摄取。培养Caco-2细胞至汇合。制备了由胆盐、单油酸甘油酯和14 C-胆固醇组成的胶束。我们首先在存在和不存在依折麦布（NPC 1 L1的特异性抑制剂）的情况下将细胞与胶束一起孵育，以观察细胞中胆固醇的摄取是否由NPC 1 L1介导。然后，我们用不同浓度的姜黄素预处理细胞24小时，然后检查这些姜黄素处理的细胞中胆固醇摄取的变化。最后，我们通过Western印迹分析和qPCR定量来确定姜黄素是否影响NPC 1 L1的表达。我们发现依折麦布以剂量依赖性方式抑制Caco-2细胞中放射性胆固醇的摄取。结果表明，在这项研究中，胆固醇的摄取是由NPC 1 L1介导的。然后，我们用25-100 μM姜黄素预处理细胞24 h，发现这种处理剂量依赖性地抑制胆固醇摄取，100 μM姜黄素获得40%的抑制。此外，我们发现姜黄素诱导的胆固醇摄取抑制与NPC 1 L1蛋白和NPC 1 L1 mRNA水平的显著降低相关，分别通过Western blot和qPCR分析。姜黄素通过抑制肠细胞中的NPC 1 L1表达来抑制胆固醇摄取。
Curcumin is a polyphenol and the one of the principle curcuminoids of the spice turmeric. Its antioxidant, anti-cancer and anti-inflammatory effects have been intensively studied. Previous in vivo studies showed that administration of curcumin also decreased cholesterol levels in the blood, and the effects were considered to be related to upregulation of LDL receptor. However, since plasma cholesterol levels are also influenced by the uptake of cholesterol in the gut, which is mediated by a specific transporter Niemann-Pick Cl-like 1 (NPC1L1) protein, the present study is to investigate whether curcumin affects cholesterol uptake in the intestinal Caco-2 cells. Caco-2 cells were cultured to confluence. The micelles composed of bile salt, monoolein, and 14C-cholesterol were prepared. We first incubated the cells with the micelles in the presence and absence of ezetimibe, the specific inhibitor of NPC1L1, to see whether the uptake of the cholesterol in the cells was mediated by NPC1L1. We then pretreated the cells with curcumin at different concentrations for 24 h followed by examination of the changes of cholesterol uptake in these curcumin-treated cells. Finally we determined whether curcumin affects the expression of NPC1L1 by both Western blot analysis and qPCR quantification. We found that the uptake of radioactive cholesterol in Caco-2 cells was inhibited by ezetimibe in a dose-dependent manner. The results indicate that the uptake of cholesterol in this study was mediated by NPC1L1. We then pretreated the cells with 25-100 μM curcumin for 24 h and found that such a treatment dose-dependently inhibited cholesterol uptake with 40% inhibition obtained by 100 μM curcumin. In addition, we found that the curcumin-induced inhibition of cholesterol uptake was associated with significant decrease in the levels of NPC1L1 protein and NPC1L1 mRNA, as analyzed by Western blot and qPCR, respectively. Curcumin inhibits cholesterol uptake through suppression of NPC1L1 expression in the intestinal cells.