【摘要】 目的初步探讨乏氧胃癌MGC细胞线粒体DNA(mtDNA)转录表达变化与乏氧损伤和放射抵抗的关系。方法将培养的胃癌细胞系MGC803分为常氧组、乏氧组(2、8、16和24h)和乏氧照射组。RT-PCR法检测常氧组和乏氧组的线粒体编码基因细胞色素c氧化酶亚单位1(cytochromeoxidasesubunit1,COⅠ)、NADH脱氢酶亚单位4(NADHdehydrogenasesubunit4,ND4)、ND5、细胞色素b(cytochromeb,cyt-b)和ATP酶亚单位6(ATPase6,ATP-6)的转录表达,流式细胞仪检测各组细胞周期时相,集落形成法分析细胞存活分数。结果胃癌MGC803细胞系COⅠ和ND4表达受乏氧影响较显著随乏氧时间的延长,COⅠ表达呈明显递减趋势,24h组下降至常氧组(0h组)的1/4;而ND4则起始升高,至8h达到高峰,为常氧组的2倍,24h降至常氧组的1/2。乏氧细胞发生G1期阻滞,16h最明显;乏氧照射组细胞随着照射前乏氧时间的延长生存率呈现升高趋势。结论具有越低COⅠ和ND4表达水平的乏氧肿瘤细胞,对放射线的抵抗性就愈强,提示增强其表达可能有利于增强乏氧肿瘤细胞对放射治疗的敏感性。更多还原

【Abstract】 OBJECTIVE:To determine the transcriptional expression of mitochondrial genome （mtDNA） in MGC803 cell lines subjected by various time-phase hypoxic dispositions, and further to discuss the influence of mtDNA transcripts on hypoxic resistance to irradiation. METHODS: RT-PCR was applied to detect the transcripts of COⅠ, ND4, ND5, cyt-b and ATPase6 in various time-phases of hypoxic MGC803 cell lines,followed by X-ray irradiation. The flow cytometry and colony forming method was conducted to evaluate the cell cycle phase and survival fraction. RESULTS: COⅠand ND4 transcripts of MGC803 cell lines were influenced remarkably by hypoxia. COⅠ transcripts decreased remarkably along with the elongation of hypoxic time, and reduced to one fourth of that in pre-hypoxia after hypoxia for 24 h. ND4 transcripts increased initially, and elevated to two folds after hypoxia for 8 h, and then reduced to one second after hypoxia for 24 h. Hypoxia resulted in G₁ phase blockage, especially after hypoxia for 16 h. The survival rate of MGC803 cells in irradiation group after hypoxia showed elevated tendency with prolonged hypoxia before irradiation. CONCLUSION: Hypoxic tumor cells with lower COⅠ and the ND4 expression levels have stronger resistance to radioactivity,referring that increasing its expression might be advantageous to enhance sensitivity of hypoxic tumor cells to radiotherapy.更多还原