Tofilon P J, Meyn R E
Radiat Res. 1987 Mar;109(3):449-55.
In these studies we have used wild-type Chinese hamster ovary cells (AA8) and a mutant cell line (UV-41) deficient in excision repair to compare sister chromatid exchange (SCE) induction after X irradiation under oxic and hypoxic conditions. X irradiation of AA8 cells under oxic conditions induced only a slight increase in SCEs, whereas at each dose tested a significantly greater number of SCEs were induced in hypoxic cells. When AA8 cells were X-irradiated and the addition of bromodeoxyuridine (BrdU) was delayed for 20 h to allow DNA lesions to be repaired, the levels of SCEs detected in both oxic and hypoxic cells returned to background levels. X irradiation of UV-41 cells also induced only a slight increase of SCEs in oxic cells, whereas a significant number of SCEs were induced in hypoxic cells. However, in contrast to results with AA8 cells, when hypoxic UV-41 cells were X-irradiated and the addition of BrdU was delayed for 20 h, the number of SCEs remained significantly above background levels. In combination with previous alkaline elution data, these results are consistent with the possibility that DNA-protein crosslinks are responsible for the SCEs induced by X irradiation of hypoxic cells. Irrespective of the mechanism(s) involved, the data presented suggest that the SCE assay may potentially aid in the detection of hypoxic tumor cells.
在这些研究中，我们使用了野生型中国仓鼠卵巢细胞（AA8）和一种切除修复缺陷的突变细胞系（UV-41），以比较在有氧和缺氧条件下X射线照射后姐妹染色单体交换（SCE）的诱导情况。在有氧条件下对AA8细胞进行X射线照射仅诱导SCEs略有增加，而在每个测试剂量下，缺氧细胞中诱导的SCEs数量显著更多。当对AA8细胞进行X射线照射并将溴脱氧尿苷（BrdU）的添加延迟20小时以允许DNA损伤得到修复时，在有氧和缺氧细胞中检测到的SCEs水平均恢复到背景水平。对UV-41细胞进行X射线照射在有氧细胞中也仅诱导SCEs略有增加，而在缺氧细胞中诱导了大量SCEs。然而，与AA8细胞的结果相反，当对缺氧的UV-41细胞进行X射线照射并将BrdU的添加延迟20小时时，SCEs的数量仍显著高于背景水平。结合先前的碱性洗脱数据，这些结果与DNA-蛋白质交联负责缺氧细胞X射线照射诱导的SCEs这一可能性一致。无论涉及何种机制，所呈现的数据表明SCE检测可能有助于检测缺氧肿瘤细胞。
