[Hepatitis B virus X protein regulates lipid metabolism and promotes the proliferation of liver cancer cells via the C/EBPa/SREBP-1 pathway].

Objective: To investigate the role and mechanism of hepatitis B virus (HBV)-encoded X protein (HBx) on the regulation of lipid metabolism and proliferation of human hepatoma cell line HepG2. Methods: HepG2 cells were transiently transfected with HBx expressing plasmid, and the cell proliferation was detected by MTT assay. Lipid droplet accumulation condition was stained by Oil Red O. Western blot was used to detect the protein levels of lipid metabolism-related genes, such as CCAAT/enhancer binding protein α (C/EBPα), sterol regulatory element binding protein-1 (SREBP-1), fatty acid synthetase (FASN) and acetyl-CoA carboxylase (ACC1). Methyl thiazolyl tetrazolium (MTT), Oil Red O staining and western blot were used to detect the effect of HBx on the regulation of lipid metabolism and proliferation of HepG2 cells under the conditions of overexpression and low expression of C/EBPα. Results: HBx had significantly promoted the proliferation of hepatoma cell line HepG2 in dose-and time-dependent manner (F = 32.82, P < 0.001; F = 58.21, P < 0.001). HBx had significantly promoted the lipid accumulation in HepG2 cells (F = 22.65, P < 0.001). Additionally, the protein levels of C/EBPα and SREBP-1 (key regulatory factors of lipid metabolism), and the rate-limiting enzymes FASN and ACC1 were significantly increased. C/EBPα overexpression had further strengthened the effect of HBx on HepG2 cell proliferation, lipid droplet accumulation, and lipid production-related gene expression. On the contrary, C/EBPα low expression had weakened HBx's promotional effect on cell proliferation, lipid droplet accumulation and lipid production-related gene expression. Conclusion: HBx may affect the lipid production and promote the proliferation of human hepatoma cell line HepG2 via the C/EBPa/SREBP-1 signaling pathway.目的： 探讨乙型肝炎病毒(HBV)编码的x蛋白(HBx)调节人肝癌细胞HepG2脂代谢和增殖的作用及其机制。 方法： 用HBx表达质粒瞬时转染HepG2细胞，四甲基偶氮唑盐（MTT）法检测细胞增殖，油红O染色检测脂滴堆积情况，Western blot检测脂代谢相关基因CCAAT/增强子结合蛋白α (C/EBPα)、固醇调节元件结合蛋白-1 (SREBP-1)、脂肪酸合成酶(FASN)和乙酰辅酶A羧化酶1 (ACC1)的蛋白水平；MTT、油红O染色和Western blot检测C/EBPα在过表达和低表达的情况下对HBx调节HepG2细胞脂代谢和增殖的影响。组间数据比较采用方差分析。 结果： HBx明显促进人肝癌细胞HepG2增殖，并呈剂量和时间依赖关系（F = 32.82，P < 0.001；F = 58.21，P < 0.001)；HBx明显促进HepG2细胞的脂质堆积(F = 22.65，P < 0.001)，且使脂质代谢的重要调节因子C/EBPα和SREBP-1、脂肪酸合成的限速酶FASN和ACC1的蛋白水平显著升高。C/EBPα过表达进一步加强了HBx对HepG2细胞增殖、脂滴堆积和脂生成相关基因表达的促进作用；相反，C/EBPα低表达削弱了HBx对细胞增殖、脂滴堆积和脂生成相关基因表达的促进作用。 结论： HBx可能通过C/EBPα/SREBP-1信号通路，影响人肝癌细胞HepG2的脂质生成，促进其增殖。.