线粒体DNA影响细胞的放射敏感性

摘要

目的　了解细胞接受辐射后，线粒体DNA(mtDNA)对细胞放射敏感性的影响。 方法　利 用缺乏mtDNA的细胞株(ρ0 细胞)、携带变异mtDNA 的细胞株(syn细胞)和携带正常mt DNA 的细胞株(ρ+ 细胞)进行体外实验研究。3种细胞株经不同剂量伽玛射线照射后，采用集 落 形成实验和流式细胞术等方法，获得3种细胞株的存活曲线(应用LQ模型)，并分析其细胞周 期的变化和比较各种细胞之间凋亡的差异。 结果　3种细胞株的存活曲线表明，ρ0 细胞 株比其它2种细胞株显示对射线有较强的抵抗(F=10.45, P=0.022)。2、5和8?Gy照射之后，ρ0 细胞株的细胞凋亡明显少于其它2种细胞株(F=14.29, P=0.0007; F=4.80, P=0.0293;F = 4.98,P=0.0154)。3种细胞株被照射后细胞周期的变化不明显。 结论　mt DNA可能是影响细胞放射敏感性的一个重要因素。%Objective　 To assess the effect of mitochondrial DNA (mtDNA) on rad iosensitivity in vitro. 　Methods　 Three human fibroblast cell lines with deficient mtDNA (ρ0 cell), mutanted mtDNA (syn- cell) and normal mtDNA (ρ+ cell) were ex posed to 137　Cs gamma ray. Cologenic formation assay was used for cell su rvival curves. Cell cycle distribution and apoptosis were analyzed by flow cytometry. 　Results　Th e ρ0 cell line showed a stronger resistance to radiation as compared to the other two cell lines by colony formation assay (P=0.022). A ma rked shoulder in the c ell survival curve was observed in the ρ0 cell at low dose irradiation. The l ow er percentage of radiation-induced apoptosis was observed in ρ0 cells after 2 , 5, and 8 Gy, as compared to those in syn- cell and ρ+ cells (P[ WTBZ = 0.017). No differ ence in cell cycle distribution was observed in three cell lines. 　Conclusion　Our results suggest that mtDNA play an important role in the radiation sensitivity in human fibroblast cells.