OH Radicals from the Indirect Actions of X-Rays Induce Cell Lethality and Mediate the Majority of the Oxygen Enhancement Effect
OH Radicals from the Indirect Actions of X-Rays Induce Cell Lethality and Mediate the Majority of the Oxygen Enhancement Effect
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DOI：
10.1667/rr13368.1
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发表时间：
2013-11-01
影响因子：
3.4
通讯作者：
Furusawa, Yoshiya
中科院分区：
文献类型：
--
作者：
Hirayama, Ryoichi;Ito, Atsushi;Furusawa, Yoshiya
我们研究了OH自由基介导的间接行动，从X射线照射对细胞杀伤野生型中国仓鼠卵巢细胞系（CHO和AA8）在有氧和缺氧条件下，并比较了直接和间接行动在这两种条件下的贡献。间接作用对细胞杀伤的贡献可以从二甲基亚砜的最大保护程度来估计，二甲基亚砜通过淬灭OH自由基来抑制间接作用，而不影响X射线对细胞杀伤的直接作用。在有氧和低氧条件下，间接作用对CHO细胞的杀伤贡献分别为76%和50%，而对AA 8细胞的间接作用则分别为85%和47%。因此，在两种细胞系中，X射线照射期间氧对细胞杀伤的间接作用得到增强。CHO和AA8细胞在10%存活水平（D-10或LD 90）下的氧增强比（OER）分别为2.68 +/-0.15和2.76 +/-0.08。分别评价了间接和直接作用的OER，CHO的OER值分别为3.75和2.01，AA8细胞的OER值分别为4.11和1.32。因此，通常接受的OER值类似于3，最好理解为间接和直接作用的OER值的平均值。这些结果表明，无论是间接和直接的细胞杀伤作用需要氧的大多数致命的DNA损伤，但是，氧在间接比直接的影响发挥更大的作用。相反，X射线直接作用引起的致死性损伤受氧浓度的影响较小。(C)2013年，辐射研究学会
We examined OH radical-mediated indirect actions from X irradiation on cell killing in wild-type Chinese hamster ovary cell lines (CHO and AA8) under oxic and hypoxic conditions, and compared the contribution of direct and indirect actions under both conditions. The contribution of indirect action on cell killing can be estimated from the maximum degree of protection by dimethylsulfoxide, which suppresses indirect action by quenching OH radicals without affecting the direct action of X rays on cell killing. The contributions of indirect action on cell killing of CHO cells were 76% and 50% under oxic and hypoxic conditions, respectively, and those for AA8 cells were 85% and 47%, respectively. Therefore, the indirect action on cell killing was enhanced by oxygen during X irradiation in both cell lines tested. Oxygen enhancement ratios (OERs) at the 10% survival level (D-10 or LD90) for CHO and AA8 cells were 2.68 +/- 0.15 and 2.76 +/- 0.08, respectively. OERs were evaluated separately for indirect and direct actions, which gave the values of 3.75 and 2.01 for CHO, and 4.11 and 1.32 for AA8 cells, respectively. Thus the generally accepted OER value of similar to 3 is best understood as the average of the OER values for both indirect and direct actions. These results imply that both indirect and direct actions on cell killing require oxygen for the majority of lethal DNA damage, however, oxygen plays a larger role in indirect than for direct effects. Conversely, the lethal damage induced by the direct action of X rays are less affected by oxygen concentration. (C) 2013 by Radiation Research Society