Sweiger S E, Petzold S J, Surowy C S, Berger S J, Dethlefsen L A, Berger N A
Radiat Res. 1986 Feb;105(2):219-26.
Previous studies have shown that the well-oxygenated but nutrient-deprived quiescent (QI) cells of the 67 murine mammary carcinoma line are significantly more sensitive to radiation-induced cell killing than the well-oxygenated proliferating (P) cells. These QI cells also sustain more initial strand breaks per radiation dose and repair them more slowly than do P cells. We now report that NAD+ levels and rates of poly(ADP-ribosylation) show a trend similar in that both these metabolic parameters are lower in QI cells by a factor of two or more. NAD+ levels were measured in acid extracts of intact monolayers using an enzymatic cycling assay, while poly(ADP-ribosylation) was followed through the incorporation of radioactive NAD+ into polymer by permeabilized cells. The major proteins labeled by [32P]NAD+ were the same in P and QI cells. However, qualitative differences exist among minor poly(ADP-ribosylated) proteins, with some bands labeled in P cells but not detectably labeled in QI cells. These studies suggest similarities between the physiological state of QI cells and that of mature resting lymphocytes.
先前的研究表明，67号小鼠乳腺癌细胞系中氧含量充足但营养物质匮乏的静止（QI）细胞比氧含量充足的增殖（P）细胞对辐射诱导的细胞杀伤更为敏感。这些QI细胞每单位辐射剂量产生的初始链断裂也更多，且修复速度比P细胞更慢。我们现在报告，NAD+水平和多聚（ADP-核糖基化）速率呈现出相似的趋势，即这两个代谢参数在QI细胞中均降低了两倍或更多。完整单层细胞的酸性提取物中的NAD+水平通过酶循环测定法进行测量，而多聚（ADP-核糖基化）则通过将放射性NAD+掺入透化细胞中的聚合物来追踪。[32P]NAD+标记的主要蛋白质在P细胞和QI细胞中相同。然而，在次要的多聚（ADP-核糖基化）蛋白质之间存在定性差异，有些条带在P细胞中被标记，但在QI细胞中未被检测到标记。这些研究表明QI细胞的生理状态与成熟静止淋巴细胞的生理状态之间存在相似性。
