Department of Pharmacology and Toxicology, University of Navarra, C/Irunlarrea 1, 31009 Pamplona, Spain and IdiSNA, Navarra Institute for Health Research, Pamplona, Spain.
Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, 97078 Würzburg, Germany.
Mutat Res Genet Toxicol Environ Mutagen. 2022 Sep;881:503520. doi: 10.1016/j.mrgentox.2022.503520. Epub 2022 Jun 23.
The comet assay is used to measure DNA damage induced by chemical and physical agents. High concentrations of test agents may cause cytotoxicity or cell death, which may give rise to false positive results in the comet assay. Systematic studies on genotoxins and cytotoxins (i.e. non-genotoxic poisons) have attempted to establish a threshold of cytotoxicity or cell death by which DNA damage results measured by the comet assay could be regarded as a false positive result. Thresholds of cytotoxicity/cell death range from 20% to 50% in various publications. Curiously, a survey of the latest literature on comet assay results from cell culture studies suggests that one-third of publications did not assess cytotoxicity or cell death. We recommend that it should be mandatory to include results from at least one type of assay on cytotoxicity, cell death or cell proliferation in publications on comet assay results. A combination of cytotoxicity (or cell death) and proliferation (or colony forming efficiency assay) is preferable in actively proliferating cells because it covers more mechanisms of action. Applying a general threshold of cytotoxicity/cell death to all types of agents may not be applicable; however, 25% compared to the concurrent negative control seems to be a good starting value to avoid false positive comet assay results. Further research is needed to establish a threshold value to distinguish between true and potentially false positive genotoxic effects detected by the comet assay.
彗星试验用于测量化学和物理试剂引起的 DNA 损伤。高浓度的测试试剂可能会导致细胞毒性或细胞死亡，这可能会导致彗星试验产生假阳性结果。对遗传毒性和细胞毒性（即非遗传毒性毒物）的系统研究试图通过建立一个细胞毒性或细胞死亡的阈值，来确定彗星试验所测量的 DNA 损伤可以被视为假阳性结果。在各种出版物中，细胞毒性/细胞死亡的阈值范围从 20%到 50%不等。奇怪的是，对来自细胞培养研究的彗星试验结果的最新文献的调查表明，三分之一的出版物没有评估细胞毒性或细胞死亡。我们建议，在彗星试验结果的出版物中，应该强制包含至少一种细胞毒性、细胞死亡或细胞增殖测定的结果。在活跃增殖的细胞中，细胞毒性（或细胞死亡）和增殖（或集落形成效率测定）的组合更为可取，因为它涵盖了更多的作用机制。将细胞毒性/细胞死亡的一般阈值应用于所有类型的试剂可能并不适用；然而，与同期阴性对照相比，25%似乎是一个避免彗星试验假阳性结果的良好起始值。需要进一步的研究来建立一个阈值，以区分彗星试验检测到的真正和潜在的假阳性遗传毒性效应。
