Cell survival after DNA damage in the comet assay

Abstract

The comet assay is widely used in basic research, genotoxicity testing, and human biomonitoring. However, interpretation of the comet assay data might benefit from a better understanding of the future fate of a cell with DNA damage. DNA damage is in principle repairable, or if extensive, can lead to cell death. Here, we have correlated the maximally induced DNA damage with three test substances in TK6 cells with the survival of the cells. For this, we selected hydrogen peroxide (H2O2) as an oxidizing agent, methyl methanesulfonate (MMS) as an alkylating agent and etoposide as a topoisomerase II inhibitor. We measured cell viability, cell proliferation, apoptosis, and micronucleus frequency on the following day, in the same cell culture, which had been analyzed in the comet assay. After treatment, a concentration dependent increase in DNA damage and in the percentage of non-vital and apoptotic cells was found for each substance. Values greater than 20–30% DNA in tail caused the death of more than 50% of the cells, with etoposide causing slightly more cell death than H2O2 or MMS. Despite that, cells seemed to repair of at least some DNA damage within few hours after substance removal. Overall, the reduction of DNA damage over time is due to both DNA repair and death of heavily damaged cells. We recommend that in experiments with induction of DNA damage of more than 20% DNA in tail, survival data for the cells are provided.

Enhancement of glycolysis-dependent DNA repair regulated by FOXO1 knockdown via PFKFB3 attenuates hyperglycemia-induced endothelial oxidative stress injury

“…DNA damage caused by high glucose alone was not detectable using comet assay ( Fig. S1B ), as more than 20% DNA in the tail is recommended in the comet assay considering the recovery capacity of cells [ 27 ]. After H 2 O 2 treatment, the average tail moment under high glucose, which was higher than that of the control group, declined after FOXO1 knockdown ( Fig.…”

Cytotoxicity and genotoxicity of bioceramic root canal sealers compared to conventional resin-based sealer

“…The genotoxicity tests were carried out to verify the effects of tested material on the genetic material of cells, which may affect their integrity 26 . Bankoglu et al reported that DNA damage above 20% negatively affected cell viability, therefore, for in vitro experiments where this level of damage was found, it is recommended to provide cell survival data in parallel 55 . Accordingly, to this recommendation, in the present study, despite many statistically significant differences between the sealants and the negative control, only BioRoot Flow and BioRoot RCS can be considered potentially genotoxic for the hGF cells after 48-h incubation.…”

XRCC1: a potential prognostic and immunological biomarker in LGG based on systematic pan-cancer analysis

“…Consequently, there is an urgent imperative to actively pursue alternative therapeutic targets and novel, highly sensitive tumor biomarkers, with the aim of unveiling innovative treatment strategies. Sustained DNA damage in cells triggers repair pathways for cell survival, and the sort of DNA damage determines which repair pathways are activated [22]. Xray repair cross-complementing 1 (XRCC1), a vital DNA repair scaffold, interacts closely with DNA ligase IIIα (Lig-III) to orchestrate the mending of DNA singlestrand breaks triggered by ionizing radiation and alkylating agents, encompassing the base excision repair (BER) and single-strand break repair (SSBR) pathways [23,24].…”