电离辐射致线粒体DNA 4977bp缺失与肿瘤细胞放射敏感性关系的初步研究

目的探讨肿瘤细胞经X线照射后线粒体DNA 4 977bp缺失率与存活分数的潜在关系。方法选用人宫颈癌细胞系(Hela细胞)、人肝癌细胞系(HepG2细胞)、人食管癌细胞系(EC-9706细胞)和人前列腺癌细胞系(PC-3细胞)4种肿瘤细胞系,经0Gy到8Gy X线照射后,采用克隆形成法测得存活分数,巢式PCR法检测线粒体DNA 4 977bp缺失率。结果肿瘤细胞放射敏感性由高到低依次是Hela细胞、HepG2细胞、EC-9706细胞和PC-3细胞。Hela细胞经1Gy X线照射后,HepG2细胞、EC-9706细胞和PC-3细胞经2Gy X线照射后均检测到线粒体DNA 4 977bp缺失。1Gy X线照射后,4种细胞线粒体DNA 4977bp缺失率比较,差异无统计学意义(P>0.05);2Gy X线照射后,Hela细胞线粒体DNA 4 977bp缺失率高于其余3种细胞(P<0.01);4Gy和8Gy X线照射后,Hela细胞线粒体DNA 4 977bp缺失率高于其余3种细胞(P<0.05),HepG2细胞和EC-9706细胞线粒体DNA 4 977bp缺失率高于PC-3细胞(P<0.01)。Hela细胞、HepG2细胞和EC-9706细胞的存活分数和缺失率之间呈负相关(r=―0.951,P<0.05;r=―0.976,P<0.01;r=―0.986,P<0.01)。结论线粒体DNA 4 977bp缺失可能是一个反映肿瘤细胞放射敏感性的生物标记。

Preliminary study of relationship between radiation-induced mitochondrial DNA 4 977 bp deletion and radiosensitivity of human tumor cell lines

Objective To explore the potential relationship of the radiation-induced mitochondrial DNA 4 977 base pairs(mtDNA 4 977 bp) deletion and the radiosensitivity of tumor cell lines.Methods The surviving fraction(SF) and the ratio of mtDNA 4 977 bp deletion were determined by clone forming assay and nested polymerase chain reaction(PCR) technique respectively after tumor cells of Hela,HepG2,EC-9706 and PC-3 were irradiated by various doses of X-ray radiation from 0 Gy to 8 Gy.Results The descending order of the four tumor cell lines′ radiosensitivities were the Hela,HepG2,EC9706 and PC-3 cells.The radiation-induced mtDNA 4 977 bp deletion were detected after 1 Gy irradiated in Hela cells and 2 Gy irradiated in HepG2,EC-9706 and PC-3 cells.The deletion rate of the four tumor cell lines had no significant difference at 1 Gy(P>0.05);but the deletion rate of Hela cells was significantly higher than that of the other tumor cell lines at 2 Gy(P<0.01);at 4 Gy and 8 Gy,the deletion rate of Hela cells was significantly higher than that of the other tumor cell lines(P<0.05),and the deletion rates of HepG2 and EC-9706 cells were higher significantly than that of PC-3 cells(P<0.01).There were negative corralations between the SF and the deletion rates in Hela,HepG2 and EC-9706 cells(r=-0.951,P<0.05;r=-0.976,P<0.01;r=-0.986,P<0.01).Conclusion The ratio of mtDNA 4 977 bp deletion may be an biological marker to predict the radiosensitivity of tumor cells.