^(60)Co照射后SMMC-7721细胞线粒体DNA部分D-loop区辐照损伤的初步研究  

Preliminary study of the radiation damage of part of D-loop region of mitochondrial DNA in human liver cancer cell line SMMC-7721 radiated by ^(60)Co γ-ray

作　　者：王洁 汪茂荣 王学敏[2] 

机构地区：[1]解放军第八一医院解放军肝病中心,南京医学硕士研究生210002 [2]第二军医大学基础医学部生物化学与分子生物学教研室,上海200433

出　　处：《医学研究生学报》2011年第3期250-255,共6页Journal of Medical Postgraduates

摘　　要：目的线粒体DNA(mitochondrial DNA,mtDNA)的变化可能损害氧的利用,导致细胞的氧化和减少能量的产生,从而引起肿瘤细胞的凋亡。文中观察SMMC-7721细胞在接受不同剂量60Coγ射线照射后,线粒体DNA部分D-loop区碱基的损伤规律及特定的断裂敏感点。方法根据人线粒体DNA非编码区的基因序列设计相应的引物序列,再通过接头介导PCR(LM-PCR)及基因扫描来检测其断裂程度、位点及规律。结果在接受不同剂量γ射线照射后,通过ligation-media-ted PCR(LM-PCR)和基因扫描检测,发现各剂量都有相同大小的片段,即存在相同的断裂位点,且这些位点并非随机分布,位点的损伤频率也随着剂量的增加而呈现递增趋势。同时,随着剂量的增加还出现了新的断裂位点,且在一定范围内出现了双链断裂。结论线粒体DNAD-loop区在60Co照射后,产生的一系列断裂敏感位点和双链断裂及本身特有的突变位点,可能对SMMC-7721细胞辐射后的细胞凋亡起到重要作用,推测mtDNA很有可能是电离辐射易感的靶点,mtDNA的变化能够作为肿瘤细胞辐照前后损伤的一个重要指标。Objective Radiotherapy is one of the main methods to treat cancer.The key of killing tumor cells is able to cause the cell DNA breaks,and lead to tumor cell death ultimately.Compared with nDNA,mtDNA is more prone to be damaged for lack of protection from histones and effective repair system.So we suspect that mtDNA is more sensitive for ionizing radiation.The change of mitochondrial DNA（mtDNA） may impair oxygen utilization,resulting in cellular oxidation and reduction of energy production,then cause tumor cell apoptosis.We selected SMMC-7721,and observed the rule of bases damage and the sensitive sites within part of D-loop region of mitochondrial DNA in SMMC-7721 after irradiation of the different dose 60Co γ-ray.MethodsPrimers of PCR detection were designed according to the sequence of the human mitochondrial DNA,and the degree,location and rule of mitochondrial DNA breaks were measured by the LM-PCR and genescan method.ResultsWe found some fragments of same length after irradiation of the different dose of 60Co γ-ray by the methods of LM-PCR and genescan.The consequence exhibited sensitive breakpoints in the D-loop region,which were non-random distribution,and showed incrementing tendency and new breakpoints arise with the dose.Moreover,there were double strand breaks in the some region of D-loop.ConclusionA series of sensitive break-points and double strand breaks in mitochondrial DNA D-loop region caused by radiation of 60Co γ-ray,and point mutations,may play an important role in the aspect of apoptosis of SMMC-7721 after radiation.We speculated that mtDNA was likely to be impressionable targets of ionizing radiation,and changes of mtDNA can be used as an important indicator of the damage of cancer cells before and after irradiation.

关 键 词：线粒体DNAD-loop区 断裂敏感点 双链断裂 Γ射线 辐照 SMMC-7721细胞 

分 类 号：Q523[生物学—生物化学]