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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。
Objective To investigate the relationship between mitochondrial DNA (mtDNA) transcription and hypoxia injury and radiation resistance in gastric cancer cell line MGC. Methods The cultured gastric cancer cell line MGC803 was divided into normoxic group, hypoxic group (2, 8, 16 and 24 hours) and hypoxic exposure group. The expression of mitochondrial cytochrome c oxidase subunit 1 (COⅠ), NADH dehydrogenases subunit 4 (ND4), ND5, and cytochrome b (cytochrome b) were detected by RT-PCR in normoxia and hypoxia groups , cyt-b) and ATPase 6 (ATP-6) were detected by flow cytometry. Cell viability was determined by colony formation assay. Results The expressions of COⅠ and ND4 in gastric cancer cell line MGC803 were significantly affected by hypoxia. With the prolongation of hypoxia, the expression of COⅠ was significantly decreased, and decreased to 1/4 in the normoxia group (0h group) Increased to peak at 8h, which was 2 times of normoxia group and decreased to 1/2 of normoxia group at 24h. G1 phase arrest in hypoxic cells, the most obvious at 16h; hypoxic exposure group cells with hypoxia before prolonged survival rate showed an upward trend. Conclusion Hypoxia tumor cells with lower expression levels of COⅠ and ND4 are more resistant to radiation, suggesting that increasing their expression may be beneficial to enhancing the sensitivity of hypoxic tumor cells to radiation therapy.