Olive P L, Banáth J P, Durand R E
Medical Biophysics Unit, British Columbia Cancer Research Centre, Vancouver, Canada.
J Natl Cancer Inst. 1990 May 2;82(9):779-83. doi: 10.1093/jnci/82.9.779.
The comet assay, which measures DNA strand breakage in individual cells, was used to examine the relation between DNA damage, cell survival, and resistance to the topoisomerase II inhibitor etoposide (VP-16). Chinese hamster V79-171b cells and a VP-16-resistant subline (VPr) were exposed to VP-16 as monolayers or spheroids. The comet assay was comparable in sensitivity to the DNA precipitation and alkali unwinding assays for detecting DNA strand breaks induced by VP-16. However, unlike conventional DNA damage assays, the comet assay also indicated heterogeneity in cell response. For V79 multicell spheroids exposed to VP-16, the external cycling cells were 50 times more sensitive to killing and DNA damage than the internal noncycling cells; the comet assay indicated the fraction of cells resistant to the drug. VPr cells, which were 10 times more resistant to killing and DNA damage by VP-16 than the parent cell line, could also be identified in mixed populations with the use of this method. These results suggest that the comet assay could be useful in predicting tumor cell response to DNA-damaging agents.
彗星试验用于检测单个细胞中的DNA链断裂情况，借此研究DNA损伤、细胞存活以及对拓扑异构酶II抑制剂依托泊苷（VP - 16）的抗性之间的关系。中国仓鼠V79 - 171b细胞和一个对VP - 16具有抗性的亚系（VPr）以单层或球体形式暴露于VP - 16。在检测VP - 16诱导的DNA链断裂方面，彗星试验在灵敏度上与DNA沉淀法和碱解旋法相当。然而，与传统的DNA损伤检测方法不同，彗星试验还显示出细胞反应的异质性。对于暴露于VP - 16的V79多细胞球体，外部循环细胞在杀伤和DNA损伤方面比内部非循环细胞敏感50倍；彗星试验可表明对该药物具有抗性的细胞比例。通过这种方法，还能在混合群体中识别出对VP - 16的杀伤和DNA损伤具有10倍抗性的VPr细胞。这些结果表明，彗星试验在预测肿瘤细胞对DNA损伤剂的反应方面可能具有实用价值。
