X射线对人肺腺癌A549细胞增殖及线粒体DNA基因表达的影响

目的 研究X射线辐射对人肺腺癌A549细胞增殖及线粒体DNA(mtDNA)基因表达的影响。方法 8 MV X射线以4 Gy的吸收剂量照射A549细胞,照射后不同时间检测细胞周期分布和凋亡率,电镜下观察细胞超微结构,人mtDNA基因表达谱芯片检测靶基因的表达变化。结果 照射后12 h即出现G₂/M期的阻滞,凋亡率在照射后48 h达到峰值,透射电镜下可见凋亡的形态改变。X射线照射后mtDNA编码基因表达呈普遍下调,包括12 h组的1种tRNA和4种mRNA基因、24 h组的2种tRNA和4种mRNA基因、48 h组的13种mRNA和2种rRNA及4种tRNA基因、72 h组的11种mRNA和2种rRNA基因。结论 X射线辐射可导致A549细胞G₂/M期阻滞,mtDNA编码基因的普遍低表达可能和辐射诱导凋亡相关。

Effect of X-ray irradiation on the proliferation and expression of mitochondrial DNA genes in A549 cells

Objective To investigate the proliferation and expression of mitochondrial DNA(mtDNA) genes in A549 human lung adenocarcinoma induced by X-ray irradiation. Methods A549 cells were irradiated with 8 MV X-ray at the absorbed dose of 4 Gy,followed by incubating the cells for different time. Cell cycle distribution and apoptotic rates were determined by flow cytometry(FCM). The apoptotic morphology was observed by transmission electron microscope(TEM),and the differential expression of mtDNA genes were detected with mtDNA oligonucleotide microarray. Results G₂/M phase arrest was manifested 12 h after exposure and the apoptotic rates reached the climax at 48 h incubation. The morphological characters of apoptosis were observed. 1 tRNA genes and 4 mRNA genes, 2 tRNA genes and 4 mRNA genes, 13 mRNA genes and 2 rRNA genes and 4 tRNA genes,11 mRNA genes and 2 rRNA genes, which were all encoded by mtDNA, were identified down-regulated at 12,24,48 and 72 h, respectively. Conclusions X-ray irradiation can cause cell cycle arrest at the G₂/M phase and the down-regulated expression of mitochondrial DNA genes may play a role in radiation-induced apoptosis.