PPARγ激动剂对肝癌细胞HepG2增殖的影响及其机制探讨

摘要

目的 观察过氧化物酶体增生物激活受体γ(PPARγ)激动剂罗格列酮体外抑制人肝癌细胞HepG2生长并探讨其作用机制.方法 MTT检测不同浓度罗格列酮(10、30、50、100 μmol/L)对HepG2细胞增殖的影响,流式细胞仪检测细胞周期和凋亡率,免疫细胞化学半定量检测PPARγ、PTEN、Bax、Bcl-2、Caspase-3蛋白表达,TUNEL和透射电镜观察HepG2细胞凋亡的形态学改变.结果 PPARγ经其配体罗格列酮激活后,可明显抑制HepG2细胞的生长并呈剂量和时间依赖关系;HepG2细胞周期出现G_0/G_1期停滞;PTEN、Bax蛋白表达上调,Bcl-2蛋白表达水平下降,Caspase-3被激活.TUNEL和透射电镜均可在罗格列酮组观察到凋亡细胞.结论 PPARγ激动剂罗格列酮可抑制肝癌细胞HepG2的生长,其主要作用机制之一是促进细胞凋亡,这可能与调节Bax、Bcl-2和Caspase-3蛋白表达有关.%Objective To observe the effect of peroxisome proliferator-activated receptor γ(PPARγ) agonist Rosiglitazone on proliferation of the human hepatoma cell line HepG2 in vitro and approach to the mechanism. Methods MTT assay was used to detect the effects of different concentrations of Rosiglitazone( 10,30,50 and 100 μmol/L,respectively)on proliferation of HepG2 cells. The apoptosis rate and the distribution in cell cycle were measured by FCM. The expression of PPARγ.PTEN, Bax,Bcl-2 and Caspase-3 in HepG2 cells was detected by using immunocytochemistry. TUNEL and transmission electron microscopy were applied to observe the apoptotic morphological changes. Results Activation of PPARγ by Rosiglitazone caused a marked growth inhibition in a dose- and time-dependent manner in HepG2 cells. HepG2 cell cycle was arrested in G_0/G_1 phase. The expression of PTEN,Bax and Caspase-3 protein was up-regulated, but that of Bcl-2 was down-regulated. Apoptotic cells were seen in Rosiglitazone-treated group by TUNEL and transmission electron microscopy. Conclusion PPARγ agonist Rosiglitazone could inhibit HepG2 cell growth,and one of the main mechanisms is to promote cell apoptosis,which may be related with the regulation of protein expression of Bax,Bcl-2 and Caspase-3.