表没食子儿茶素没食子酸酯通过AKT/SREBP-1/FASN信号通路调节HepG2细胞脂代谢的作用

Epigallocatechin gallate regulates the lipid metabolism of HepG2 cells through the AKT/SREBP-1/FASN signaling pathway

关键词:  表没食子儿茶素没食子酸酯  HepG2  脂代谢  脂肪酸从头合成

Key words:  epigallocatechin gallate(EGCG)  HepG2  lipid metabolism  de novo lipogenesis

摘要:

目的 研究表没食子儿茶素没食子酸酯（epigallocatechin gallate，EGCG）通过AKT/SREBP-1/FASN信号通路抑制脂肪酸从头合成，调节肝癌HepG2细胞脂代谢的作用。方法 运用CCK-8法检测不同浓度EGCG对HepG2细胞的细胞毒性；采用油酸诱导建立HepG2细胞脂肪变性模型，运用油红O染色法观察EGCG对油酸诱导HepG2细胞脂肪变性的改善作用，测定细胞内甘油三酯（triglycerides，TG）的含量；运用实时荧光定量PCR检测胆固醇调节元件结合蛋白1（sterol regulatory element binding protein-1，SREBP-1）、脂肪酸合成酶（fatty acid synthase，FASN） mRNA的表达水平；Western blotting检测p-AKT^Thr308、SREBP-1、FASN蛋白的表达水平；运用AKT质粒瞬时转染进一步确证EGCG对p-AKT^Thr308、SREBP-1、FASN蛋白表达水平的影响。结果 油酸诱导后，运用油红O染色可见HepG2细胞内具有大量脂质累积，TG含量显著升高（P<0.05），FASN、SREBP-1 mRNA表达水平升高，p-AKT^Thr308、SREBP-1、FASN蛋白表达水平升高，AKT质粒转染后p-AKT^Thr308、SREBP-1、FASN蛋白表达水平升高（P<0.05）；给予EGCG （20，40 μmol·L^–1）作用后，细胞内脂质累积明显减少，TG含量显著降低（P<0.05），FASN、SREBP-1的mRNA表达降低，p-AKT^Thr308、SREBP-1、FASN蛋白表达水平降低（P<0.05）。结论 EGCG可能通过调控AKT/SREBP-1/FASN信号通路抑制脂肪酸从头合成，发挥调节HepG2细胞脂代谢的作用。

Abstract:

OBJECTIVE To investigate the role of epigallocatechin gallate(EGCG) in inhibiting de novo lipogenesis and regulating lipid metabolism in HepG2 cells through the AKT/SREBP-1/FASN signaling pathway. METHODS CCK-8 method was used to detect the cytotoxicity of EGCG at different concentrations on HepG2 cells. Oil red O staining was used to observe the effect of EGCG on steatosis of HepG2 cells induced by oleic acid and determine the content of triglyceride(TG). The mRNA levels of sterol regulatory element binding protein-1(SREBP-1) and fatty acid synthase(FASN) were detected by RT-PCR. Then protein expression levels of p-AKT^Thr308, SREBP-1 and FASN were detected by Western blotting. Moreover, the effect of EGCG on the expression levels of p-AKT^Thr308, SREBP-1 and FASN were further confirmed by transient transfection with AKT plasmid. RESULTS A large amount of lipid was accumulated in HepG2 cells induced by oleic acid, the TG content and the mRNA or protein expression levels of p-AKT^Thr308, SREBP-1 and FASN were significantly increased(P<0.05). Furthermore, the protein expression levels of p-AKT^Thr308, SREBP-1 and FASN were increased after transfection with AKT plasmid(P<0.05). After treatment with EGCG(20, 40 μmol·L^-1), intracellular lipid accumulation and TG content were significantly reduced(P<0.05), mRNA or protein expression levels of p-AKT^Thr308, SREBP-1 and FASN were decreased(P<0.05). CONCLUSION EGCG may regulate the lipid metabolism of HepG2 cells by inhibiting the de novo lipogenesis through the regulation of AKT/SREBP-1/FASN signaling pathway.