苦参素对人肺腺癌A549细胞放射敏感性的影响及其机制

Effect of oxymatrine on radiosensitivity of A549 cells and its possible molecular mechanism

目的:观察苦参素联合放射线照射对人肺腺癌A549细胞增殖率以及DNA依赖性蛋白酶(DNA dependent protein kinase,DNA-PK)的两类结构亚基DNA-PKcs及Ku80 mRNA表达的影响。方法:根据不同的处理条件,将A549细胞分为对照组,单纯照射组,单纯药物组,药物联合照射组。通过CCK-8法检测细胞增殖率,并应用实时荧光定量PCR技术检测DNA-PKcs及Ku80 mRNA的相对表达水平。结果:苦参素明显抑制A549细胞的增殖,呈时间和剂量依赖性(P<0.05),其24 h和48 h的半数抑制浓度(IC50)值分别为3.2 g/L和2.4 g/L。单纯照射组随着照射时间的延长和放射线剂量的增加,细胞增殖率明显下降(P<0.05);药物联合照射组细胞随着照射时间的延长,细胞增殖率也随之明显下降(P<0.05);在同一时间点,药物联合照射组细胞增殖率下降比单纯照射组更为明显(P<0.05)。此外,在单纯照射组中,A549细胞DNA-PKcs及Ku80 mRNA的相对表达水平随着照射时间的延长和放射线剂量的增加而增高(P<0.01);较对照组而言,单纯药物组DNA-PKcs及Ku80 mRNA的相对表达水平明显下调(P<0.01);与对应的单纯照射组比较,药物联合照射组DNA-PKcs及Ku80 mRNA相对表达水平明显下调(P<0.01)。结论:苦参素对肿瘤细胞具有放射线增敏作用。辐射可明显增加肺癌细胞DNA-PKcs及Ku80 mRNA的相对表达水平,苦参素对A549细胞的放射线增敏效应至少部分是与抑制DNA-PKcs及Ku80 mRNA的表达,从而抑制DNA损伤修复有关。

Objective: To investigate the mechanism of oxymatrine in enhancing the sensitivity of lung cancer cells to radiation. Methods: The A549 cells were divided into control group,radiation group,drug group,drug plus radiation group according to treatment condition. The cell counting kit-8 assay was used to determine proliferation rate. The real-time quantitative PCR assays were conducted to measure DNA-PKcs and Ku80 mRNA expression levels at 24 h and 48 h following treatment with oxymatrine,or radiation,or oxymatrine plus radiation. Results: Oxymatrine significantly inhibited the proliferation of A549 cells in a dose and time dependent manner( both P < 0. 05). IC50 of A549 cells for oxymatrine at 24 h and 48 h were3. 2 g / L and 2. 4 g / L,respectively. The proliferation rates of A549 cells in the radiation group were decreased in a time and dose dependent manner( both P < 0. 05). At the same time points,the cell proliferation rates in the drug plus radiation group were dropped markedly when compared with the radiation group( P < 0. 05). Additionally,the relative expression levels of DNA-PKcs and Ku80 mRNA were increased in a dose and time dependent manner in the radiation group( both P < 0. 01). The relative expression levels of DNA-PKcs and Ku80 mRNA in the drug plus radiation group were reduced significantly as compared with inthe radiation group( P < 0. 01). Conclusion: Oxymatrine enhanced the sensitivity of A549 cell to radiation,at least partially,by inhibiting DNA-PKcs and Ku80 mRNA expression and damage of DNA damage repair mechanisms.