27-羟基胆固醇激活LXR信号通路调节肺癌细胞的增殖

摘要

目的:探讨胆固醇代谢产物27-羟基胆固醇 (27-OHC) 对肺癌细胞增殖的影响.方法:采用不同浓度 (0、0.3125、0.625、1.25、2.5、5和10μmol/L) 的27-OHC处理人肺癌A549细胞24～48 h, 随后使用细胞计数试剂盒 (CCK-8法) 评估细胞活力, 采用流式细胞术检测细胞周期, Ed U实验检测细胞增殖状况, 采用总胆固醇检测试剂盒检测细胞内胆固醇水平, real-time PCR及Western blot法分别检测胆固醇代谢相关分子的表达.结果:27-OHC以剂量和时间依赖性显著降低A549肺癌细胞的活力 (P <0.01) , 抑制细胞增殖 (P <0.05) .27-OHC通过上调肝X受体 (LXR) 信号通路下游靶蛋白ATP结合盒转运蛋白A1 (ABCA1) 的表达, 促进细胞内胆固醇的外排, 同时下调低密度脂蛋白受体 (LDLR) 和3-羟基-3-甲基戊二酰辅酶A还原酶 (HMG-CR) 的表达, 减少胆固醇的摄入和从头合成, 导致细胞内胆固醇水平降低, 细胞活力下降 (P <0.01) .此外, LXR通路被5μmol/L GSK2033部分阻断后, 27-OHC对A549细胞活力的抑制作用显著减弱 (P <0.05) .结论:27-OHC通过激活LXR通路抑制A549细胞增殖.%AIM:To investigate the effect of cholesterol metabolite 27-hydroxycholesterol (27-OHC) on the proliferation of lung cancer cells.METHODS:Human lung cancer A549 cells were treated with 27-OHC at different concentrations (0, 0.3125, 0.625, 1.25, 2.5, 5 and 10μmol/L) for 24～48 h.The cell viability, cell cycle, cell proliferation, the intracellular cholesterol levels and cholesterol metabolism-related molecule expression were subsequently assessed by CCK-8 assay, flow cytometry, Ed U staining, tissue total cholesterol detection kit, real-time PCR and Western blot.RESULTS:27-OHC decreased the viability of the A549 cells in a dose-and time-dependent manner (P<0.01) and inhibited the cell proliferation (P<0.05).The expression of typical liver X receptor (LXR) downstream target proteins including ATP-binding cassette transporter A1 (ABCA1) , low-density lipoprotein receptor (LDLR) , and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CR) were modulated, which promoted the efflux of intracellular cholesterol, and reduced cholesterol influx and de novo synthesis, resulting in decreased intracellular cholesterol levels and cell viability.Furthermore, the inhibitory effect of 27-OHC on A549 cell viability was significantly attenuated after the LXR pathway was partially blocked by 5μmol/L GSK2033 treatment (P<0.05).CONCLUSION:27-OHC inhibits A549 cell proliferation via activation of LXR signaling pathway.