Temperature dependence of adriamycin-induced DNA damage in L1210 cells.
Temperature dependence of adriamycin-induced DNA damage in L1210 cells.
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发表时间：
1989-10
期刊：
影响因子：
11.2
通讯作者：
P. Vichi;S. Robison;T. Tritton
中科院分区：
文献类型：
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作者：
P. Vichi;S. Robison;T. Tritton
我们报告碱性洗脱实验，揭示了温度依赖性的DNA损伤，单链断裂和DNA-蛋白质交联，在L1210细胞暴露于阿霉素。DNA损伤，在37摄氏度相当于几百拉德的电离辐射暴露，随着药物暴露温度的降低而减少。在低于约15 ℃的所有温度下，在暴露于阿霉素的L1210细胞中没有检测到DNA损伤，即使在相对高的剂量下。低温失活不是由于细胞内药物的再分布，因为在37和0 ℃下，在细胞核和细胞质位置都有高浓度的阿霉素。DNA损伤的温度曲线与细胞毒性曲线平行，即，在低温下，该药物作为细胞毒性剂是完全无活性的（P. Lane，P. Vichi，D. L. Bain和T. R. Tritton，Cancer Res.，47：4038-4042，1987）。因此，DNA断裂和细胞杀伤似乎彼此相关。然而，当我们检查从L1210细胞分离的细胞核中的DNA损伤时，我们发现低温不能维持阿霉素诱导的单链断裂或DNA-蛋白质交联是不存在的。因此，在细胞核中，药物可以在低温下引起DNA损伤，而在整个细胞中则不能。拓扑异构酶II是一种在接触嵌入剂的细胞中催化DNA损伤的酶，它保留了其在0 ℃下解开P4 DNA的催化活性，并被药物诱导以改变pBR 322超螺旋的释放，因此该酶的低温失活不能解释结果。我们建议，完整的L1210细胞具有控制DNA损伤的调节因子，可能通过拓扑异构酶II，但当细胞核被分离时丢失。
We report alkaline elution experiments that reveal the temperature dependence of DNA lesions, both single-strand breaks and DNA-protein cross-links, in L1210 cells exposed to Adriamycin. DNA damage, which at 37 degrees C is equivalent to several hundred rads of ionizing radiation exposure, diminishes as the temperature of drug exposure is lowered. At all temperatures below about 15 degrees C no DNA damage is detectable in L1210 cells exposed to Adriamycin, even at relatively high doses. The low temperature inactivity is not due to a redistribution of intracellular drug since at both 37 and 0 degrees C there is a high concentration of Adriamycin in both nuclear and cytoplasmic locations. The temperature profile for DNA damage parallels the profile for cytotoxicity, i.e., at low temperature, the drug is completely inactive as a cytotoxic agent (P. Lane, P. Vichi, D. L. Bain, and T. R. Tritton, Cancer Res., 47:4038-4042, 1987). Thus, DNA breaks and cell kill appear to be correlated with one another. However, when we examined DNA lesions in nuclei isolated from L1210 cells we found that the low temperature inability to sustain Adriamycin-induced single-strand breaks or DNA-protein cross-links was absent. In nuclei, then, the drug can provoke DNA damage at low temperature, while in whole cells it cannot. Topoisomerase II, an enzyme implicated in catalyzing DNA lesions in cells exposed to intercalating agents, retains its catalytic activity both to unknot P4 DNA at 0 degrees C, and to be induced by drug to alter the release of pBR322 supercoils, so a low temperature inactivation of this enzyme cannot explain the results. We propose that intact L1210 cells have a regulatory factor which controls DNA damage, possibly through topoisomerase II, but which is lost when nuclei are isolated.