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Genotoxicity of several clinically used topoisomerase II inhibitors
Abstract:
DNA topoisomerase II is an essential nuclear enzyme that modulates DNA topology during multiple cellular processes such as DNA replication and chromosome segregation. Several important clinical antitumor drugs and antibiotics act through inhibition of topoisomerase II. There are a number of different steps in the action of topoisomerase II, all of which are potential targets for inhibition through drugs and also for cellular and genetic toxicity as well as for mutagenesis. We have investigated and compared the genotoxicity and mutagenicity of the mechanistically different topoisomerase II inhibitors m-amsacrine, mitoxantrone, etoposide, genistein, ICRF 193, and berenil using the in vitro micronucleus test, single cell gelelectrophoresis (comet assay) and the mutation assay (tk-locus) in L5178Y mouse lymphoma cells. All six compounds induced micronuclei and all except berenil were mutagenic. M-amsacrine, mitoxantrone, etopside and genistein induced DNA migration in the comet assay, whereas ICRF 193 was only weakly positive and berenil was negative in this test. Our results are in good agreement with the compounds' proposed mechanisms of interaction with topoisomerase II.
Insights
This study assessed the genotoxicity and mutagenicity of six DNA topoisomerase II inhibitors. Most inhibitors caused DNA damage and mutations, aligning with their known mechanisms of action.
Area of Science:
- Molecular Biology
- Genetics
- Pharmacology
Background:
- DNA topoisomerase II is crucial for DNA topology regulation during replication and segregation.
- Inhibition of DNA topoisomerase II is a key mechanism for antitumor drugs and antibiotics.
- Drug interactions with topoisomerase II present targets for therapeutic intervention and potential toxicity.
Purpose of the Study:
- To investigate and compare the genotoxicity and mutagenicity of six mechanistically distinct DNA topoisomerase II inhibitors.
- To evaluate the in vitro genotoxic and mutagenic profiles of m-amsacrine, mitoxantrone, etoposide, genistein, ICRF 193, and berenil.
- To correlate the observed toxicities with the proposed mechanisms of topoisomerase II inhibition.
Main Methods:
- Utilized the in vitro micronucleus test to assess chromosomal damage.
- Employed the single-cell gel electrophoresis (comet assay) to detect DNA strand breaks.
- Applied the mutation assay at the tk-locus in L5178Y mouse lymphoma cells to determine mutagenicity.
Main Results:
- All six compounds induced micronuclei, indicating chromosomal damage.
- Five of the six compounds (all except berenil) were found to be mutagenic.
- M-amsacrine, mitoxantrone, etoposide, and genistein induced significant DNA migration in the comet assay, suggesting DNA strand breaks. ICRF 193 showed weak positive results, and berenil was negative.
- The observed genotoxicity and mutagenicity results were consistent with the known mechanisms of action for each topoisomerase II inhibitor.
Conclusions:
- The study successfully characterized the genotoxic and mutagenic potential of diverse DNA topoisomerase II inhibitors.
- The findings support the hypothesis that interactions with DNA topoisomerase II can lead to various forms of genetic toxicity.
- This research provides valuable data for understanding the safety profiles of topoisomerase II-targeting agents and informs drug development strategies.