姜黄素抑制Caco-2细胞胆固醇吸收的作用及机制研究

THE INHIBITORY EFFECT OF CURCUMIN ON Caco-2 CELLS CHOLESTEROL ABSORPTION AND THE MECHANISM

目的探讨姜黄素对Caco-2细胞胆固醇吸收的影响以及可能机制。方法建立Caco-2细胞单层模型,分别用25、50、100μmol/L姜黄素或胆固醇吸收转运蛋白尼曼-匹克C1型类似蛋白1(NPC1L1)的抑制剂依折麦布孵育细胞24h或2h后,再用[14C]-胆固醇微胶溶液孵育细胞2h。用液闪计数仪检测细胞胆固醇吸收量,荧光定量PCR和Western blot检测NPC1L1的基因和蛋白表达量。结果 Caco-2细胞[14C]-胆固醇吸收可被依折麦布呈浓度依赖性地抑制,表明本研究建立的单层Caco-2细胞模型的胆固醇吸收是由NPC1L1所介导的。姜黄素能有效的下调NPC1L1的基因及蛋白表达水平,降低Caco-2细胞胆固醇吸收,100μmol/L姜黄素可引起40%胆固醇吸收下降。结论姜黄素能够降低Caco-2细胞胆固醇吸收,这可能与其抑制NPC1L1表达有关。

Objective To investigate the effects of curcumin on intestinal cholesterol absorption and the possible mechanisms.Method The delipidized fetal bovine serum and the micelles composed of bile salt,monoolein,and 14C-cholesterol were prepared.Caco-2 cells were pretreated with 25,50,100 μmol/L curcumin or Niemann-Pick C1-Like 1（NPC1L1） inhibitor ezetimibe for 24h or 2h respectively,and then incubated with cholesterol micelle solution for anther 2h.The absorption of cholesterol in Caco-2 cells was determined by liquid scintillation counting.The mRNA and protein expression of NPC1L1 was analyzed by qPCR and Western blot respectively.Results The absorption of radioactive cholesterol in Caco-2 cells was inhibited by ezetimibe in dose-dependent manner.The absorption of cholesterol was mediated by NPC1L1.The cells were pretreated with 25-100 μmol/L curcumin for 24 h and cholesterol absorption was 40% inhibited dose-dependently by 100 μmol/L curcumin.In addition,the curcumin induced inhibition of cholesterol absorption was associated with significant decrease in the levels of NPC1L1 mRNA and NPC1L1 protein.Conclusion Curcumin inhibits cholesterol absorption by suppression of NPC1L1 expression.