幽门螺杆菌对胃癌细胞线粒体DNA编码的细胞色素氧化酶基因表达的影响

Effects of Helicobacter pylori on Expression of Cytochrome Oxidase mRNA Encoded by Mitochondrial DNA in Gastric Carcinoma Cells

背景:既往研究表明胃黏膜细胞核基因组有线粒体DNA(mtDNA)片段整合,且这种整合与幽门螺杆菌(H.pylori)感染有关,并参与胃癌的发生。mtDNA片段与核基因整合后,是否会引起所编码基因表达的改变,这种改变是否与H.pylori感染有关尚不明确。目的:观察H.pylori作用于胃癌细胞后线粒体编码基因细胞色素氧化酶(COX)Ⅰ、COXⅡ和COXⅢmRNA表达的变化,探讨H.pylori致胃癌的分子机制。方法:将6μl/mlH.pylori培养滤液与胃癌细胞分别作用4h、8h和12h,收集细胞,提取RNA,应用逆转录聚合酶链反应(RT-PCR)检测各时间点COXⅠ、COXⅡ和COXⅢmRNA的表达。结果:H.pylori作用4h后,线粒体COXⅠ、COXⅡ和COXⅢmRNA的表达有所降低,8h时下降更明显,12h时段下降速度减缓;除COXⅡ4h时与对照组无差异外,其余各时间点的表达量均显著低于对照组(P<0.05)。结论:H.pylori可引起胃癌细胞线粒体编码基因COXⅠ、COXⅡ和COXⅢmRNA表达下调,影响线粒体的功能。

Background：It had been revealed that the fragments of mitochondrial DNA （mtDNA） were integrated with the nuclear genes of gastric mucosal cells which were related to Helicobacter pylori （ H. pylori ） infection and involved in gastric carcinogenesis. When mtDNA fragments are integrated with nuclear genes, whether it will change the expression of the encoded genes and whether the alteration is related to H. pylori infection remain uncertain. Aims： To study the effects of H. pylori on expression of cytochrome oxidase （COX） I. II and m mRNA encoded by mtDNA in gastric carcinoma ceils, and to appraise the potential role of H. pylori in gastric carcinogenesis. Methods： After treated with 6 μl/ml concentrated H. pylori culture supernatant for 4, 8 and 12 hours, respectively, the gastric carcinoma cells were collected and the RNA was extracted. Reverse transcriptase polymerase chain reaction （RT-PCR） was used to detect the expression of COX Ⅰ, COX Ⅱ and COX Ⅲ mRNA at different time points. Results： The expression of COX Ⅰ, COX Ⅱ and COX Ⅲ mRNA decreased gradually after exposure to H. pylori for 4 hours, and the decrease was more significant at the 8 hour. After exposure for 12 hours, the decrease of velocity slowed down. The expressions of COX Ⅰ , COX Ⅱ and COX Ⅲ mRNA at different time points were significantly lower than those in the control group （P〈0.05）, except the expression of COXⅡ after exposure for 4 hours. Conclusions： H. pylori can affect the mitochondrial function by down-regulating the expression of mtDNA encoded COX Ⅰ, COX Ⅱ and coxm mRNA in gastric carcinoma cells.