脂多糖促进H_2O_2降低羧酸酯酶1/2活性抑制肝癌HepG2细胞存活

Combined lipopolysaccharide with H_2O_2 inhibit HepG2 cells survival by decreasing carboxylesterase 1/2 activation

目的阐明LPS对肝癌HepG2细胞增殖和凋亡的作用及其潜在机理。研究脂多糖(lipopolysaccharide,LPS)对人肝癌HepG2细胞中羧酸酯酶1(Human carboxylesterase 1,CES1)、羧酸酯酶2(Human carboxylesterase 2,CES2)活性和表达的影响。方法 MTT检测不同剂量LPS(0mg/L,1.0mg/L,3.0mg/L,5.0mg/L,10.0mg/L)与H_2O_2(0.5mm)分别处理或共孵育12h,24h,48h对细胞增殖的影响。采用Tunel技术检测LPS对细胞凋亡的影响。酶学测定LPS对HepG2细胞中HCEs酶活性的影响。采用Real-time PCR和Western blot检测HepG2细胞中CES1、CES2在mRNA水平和蛋白水平变化。结果 LPS和H_2O_2(0.5mm)单独处理对HepG2细胞增殖和凋亡无显著影响。LPS与H_2O_2(0.5mm)共孵育剂量依赖性的降低HepG2细胞增殖,促进HepG2细胞凋亡,降低HCEs酶活性。此外,LPS和H_2O_2(0.5mm)共孵育可明显降低肝癌HepG2细胞中CES1和CES2的mRNA和蛋白水平的表达,降低趋势呈现剂量-效应关系。结论我们发现LPS和H_2O_2(0.5mm)共孵育能够显著降低细胞增殖,促进细胞凋亡。此机制可能与LPS明显降低肝癌HepG2细胞中CES1和CES2的表达和活性有关。提示肝肿瘤细胞在炎症状态下,羧酸酯酶对药物代谢的能力下降。本研究为临床肝癌治疗提供新的理论依据和治疗靶点。

Objective To explore the function and mechanism of LPS on HepG2 cells proliferation and apoptosis, and to investigate the effect of lipopolysaeeharide （LPS） on the activity and expression of earboxylesterase 1 （ CES1 ） and carboxylesterase 2 （CES2） in human hepatic carcinoma HepG2 cells. Methods MTT assay was performed to measure cell proliferation by treatment combined the different dosages of LPS（0 mg/L, 1.0mg/L, 3.0 mg/L, 5.0 mg/L, 10.0mg/L）with H2O2 （0.5 mm） . Tunel assay was used to assess cell apoptosis. Enzymology was used to detect the effects of LPS on the activity of HCEs. We next measured the mRNA and protein expressions of CES1 and CES2 in HepG2 ceils by using real - time PCR and western blot. Results LPS or H2O2 （0.5 ram） treatment alone had no effect on cell proliferation and apoptosis. Combined LPS with H2O2 （0.5ram） could reduce HepG2 cells proliferation, promote its apoptosis, and decrease the activity of HCEs. In addition, combined LPS with H2O2 could significantly decrease the expression of mRNA and protein levels of CES1 and CES2 in a dose - dependent manner in HepG2 ceils. Conclusion We found that combined LPS with H2O2 （0.5 mm） could inhibit cell proliferation and promote its apoptosis. The mechanism may be related to LPS down - regulates the expressions and activity of CESI and CES2 in human hepatic carcinoma HepG2 cells. The above result indicated that the ability of metabolism was decreased by treatment with LPS. Our study provided a novel potential therapeutic target for the clinical management of human hepatic carcinoma.