Winegar R A, Land M C, Morgan W F
Laboratory of Radiobiology and Environmental Health, University of California, San Francisco 94143-0750.
Biochem Biophys Res Commun. 1989 May 15;160(3):1079-84. doi: 10.1016/s0006-291x(89)80113-5.
We have transfected a Chinese hamster ovary cell line (CHO 6) with a plasmid that inducibly expresses the Eco RI restriction endonuclease gene in the presence of cadmium sulfate (CdSO4). Expression of Eco RI results in DNA double-strand breaks, which can lead to chromosome aberrations. The new line, designated CHO 10, also has a low level of constitutive expression of Eco RI in the absence of CdSO4 without any cytogenetic effect. This suggested that these cells may be efficient at repairing low levels of DNA double-strand breaks. To test this, both cell lines were exposed to ionizing radiation, and aberration yields were analyzed with or without induction of Eco RI. CHO 10 cells showed increased radiosensitivity after G1 irradiation, but after G2 exposure, only doses greater than or equal to 0.4 Gy caused more damage in CHO 10 cells. We conclude that CHO 10 cells can tolerate constitutive expression of Eco RI, but that when the cells are subjected to additional stress, in this case ionizing radiation, they become very sensitive to DNA double-strand breaks.
我们用一种质粒转染了中国仓鼠卵巢细胞系（CHO 6），该质粒在硫酸镉（CdSO4）存在的情况下可诱导表达Eco RI限制性内切酶基因。Eco RI的表达会导致DNA双链断裂，进而可能导致染色体畸变。新的细胞系命名为CHO 10，在不存在CdSO4的情况下，它也有低水平的Eco RI组成型表达，且没有任何细胞遗传学效应。这表明这些细胞可能在修复低水平的DNA双链断裂方面效率较高。为了验证这一点，将这两种细胞系都暴露于电离辐射下，并在诱导或不诱导Eco RI的情况下分析畸变率。CHO 10细胞在G1期照射后放射敏感性增加，但在G2期暴露后，只有剂量大于或等于0.4 Gy才会在CHO 10细胞中造成更多损伤。我们得出结论，CHO 10细胞能够耐受Eco RI的组成型表达，但当细胞受到额外的应激，在这种情况下是电离辐射时，它们对DNA双链断裂变得非常敏感。
