稳定表达HBx的HepG2细胞对罗格列酮敏感性的影响及其机制研究

Sensitivity of HepG2 cells with stably expressing HBx via rosiglitazone and its mechanism

目的:构建稳定表达x基因编码的乙型肝炎病毒x蛋白(xprotein of hepatitis B virus,HBx)的HepG2细胞,检测其对罗格列酮敏感性的变化,并探讨HBx与过氧化物酶体增殖物激活受体γ(peroxisome proliferators activated receptor γ,PPARγ)之间的相互作用在原发性肝癌形成过程中的可能机制。方法:构建pIRES2-HBx真核表达质粒,筛选稳定表达HBx的HepG2细胞;MTT法检测细胞对罗格列酮的敏感性;免疫细胞化学法检测PPARγ定位的变化;RT-PCR和Western印迹法检测PPARγ的表达。结果:成功构建pIRES2-HBx真核表达质粒,获得稳定表达HBx的HepG2细胞;罗格列酮对该细胞的抑制作用明显降低(P<0.05),经丝裂原活化蛋白激酶/细胞外信号调节激酶的激酶1(mitogen-activated protein kinase/extra-cellular signal-regulated kinase kinase 1,MEK1)抑制剂PD98059预处理后,抑制率有所回升;PPARγ表达量变化的差异无统计学意义,但在细胞中的表达位置发生改变,即从细胞核转至细胞质。结论:HBx可降低HepG2细胞对罗格列酮的敏感性,可能的机制是HBx可改变PPARγ在细胞内的定位以及与DNA的结合能力,并通过磷酸化途径影响PPARγ与配体的结合能力及其活性。

Objective：To establish a HepG2 cell line with stable expression of x protein of hepatitis B virus （ HBx）, detect its sensitivity to rosiglitazone, and explore the mechanism for the role of the interaction of HBx with peroxisome proliferato-activated receptor γ（PPARγ） in hepatocarcinogenesis. Methods： This work constructed pIRES2-HBx eukaryotic expression plasmid, screened HepG2 cell clone with stable expression of HBx. The sensitivity of HBx-expressing HepG2 cells to rosiglitazone was assessed by MTT assay. The change in PPARγ location was detected by immunocytochemistry. The mRNA and protein expressions of PPARγ were determined by RT-PCR and Western blotting respectively. Results： This work successfully constructed pIRES2-HBx eukaryotic expression plasmid and obtained the HepG2 cell line with stable expression of HBx. The inhibitory effect of rosiglitazone on HBx-expressing HepG2 cells decreased obviously, but the inhibitory effect was partly reversed when the ceils were pretreated with PD98059, an inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1 （ MEK1 ）. The difference in PPARγ/expression was not significant. But the location of PPARγ was changed. It moved from nucleus to cytoplasm. Conclusion： HBx reduces the sensitivity of HepG2 cells to rosiglitazone. The possible mechanism is that HBx changes the site-specific location of PPARγ and decreases its binding ability to DNA, thus influence the binding of PPARγ to its ligand and the activity of PPARγ through phosphorylation pathway.