软脂酸对肝癌HepG2细胞脂质沉积的影响和Srebp1c甲基化调控机制

The effects of palmic acid on induced lipidosis in HepG2 cells and the mechanism of Srebp1c methylation

目的观察饱和游离脂肪酸(软脂酸,PA)对HepG2细胞脂质沉积的影响和固醇调节元件结合蛋白1c(Srebp1c)甲基化调控机制。方法体外培养人肝癌细胞系HepG2细胞,对照组不作处理,软酯酸(PA)组用0.2mmol/L的PA刺激细胞。采用油红O染色检测HepG2细胞内脂质沉积情况;qPCR和Western blot分别测定细胞内基因和蛋白表达;甲基化特异性PCR(MS-PCR)检测HepG2细胞Srebp1c甲基化状态。结果 0.2 mmol/L的PA刺激能使HepG2细胞发生脂质沉积。与对照组比较,PA组HepG2细胞Srebp1c(P=0.004 6)、乙酰辅酶A羧化酶(ACC)(P=0.023 0)和脂肪酸合酶(FAS)(P=0.012 5)的mRNA表达均异常升高,Srebp1c蛋白表达升高(P<0.05),Srebp1c启动子甲基化水平降低(P=0.0253)。结论游离脂肪酸可以导致HepG2细胞脂质沉积性损伤,Srebp1c甲基化程度降低可能是重要原因。

Objective To observe the effects and mechanism of palmic acid（PA）on induced lipidosis in HepG2 cells. Methods HepG2 cells were cultured in vitro. The control group and PA group（0.2 mmol/L）were established according to the experimental requirements. The lipidosis was measured by Oil Red O staining. The mRNA and protein expression were determined by qPCR and Western-blot,respectively. The Srebp1 c gene methylation status was determined by Methylation Specific PCR（MS-PCR）.Results Compared with control group,0.2 mmol/L PA treatment could induce lipidosis. Meanwhile,PA group had higher levels of Srebp1 c,ACC and FAS mRNA expression than those of control group,and the PA treatment increased the protein expression of Srebp1 c,and also the 0.2 mmol/L PA treatment decreased the degree of Srebp1 c gene methylation（P=0.025 3）. Conclusion The free fatty acids may be a high risk factor of lipidosis injure in HepG2 cells;klorho promoter methylation may play an important role.