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Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development
Published on: April 15, 2013
Rapid analysis of base-pair substitutions induced by mutagenic drugs through their oxygen radical or epoxide
A Abu-Shakra1, E T McQueen, M L Cunningham
1Department of Biology, North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707, USA. abushak@wpo.nccu.edu
Abstract:
Among the drugs that induce base-pair substitution mutations in the Salmonella reversion assay are the nitric oxide (NO)-delivery drug, diethylamine NONOate (DeaNO), and the ovarian cancer chemotherapeutic drug, treosulphan (TE). The present study compared the mutation spectra generated by DeaNO and TE in the hisG46 strains, TA1535 and TA100, the hisG428 strain, TA102, and the six Ames II 7000 series strains. Using these strains, it was feasible to conduct rapid analysis of the type and magnitude of induced mutation without resorting to DNA amplification and sequencing. A putative hydrolysis product of TE, 1,2:3,4-diepoxybutane (DEB), and hydrogen peroxide (H(2)O(2)) were included in the study to allow for further comparisons between epoxide-induced damage and that induced by the hydroxyl radical. TE (0.93 micromole/pl) induced 16. 8-fold-over-background reversion or a mutagenicity ratio (MR) of 16. 8 in TA1535. The response was weaker in TA100 (MR of 3), and negative in strain TA102. Only two Ames II strains demonstrated sensitivity to TE, and they were TA7004 (CG:AT) and TA7005 (GC:AT). Like TE, DeaNO (33 micromole/pl) was mutagenic in TA1535 (MR of 24.6), TA100 (MR of 5.3), TA7004 (MR of 13.7), and TA7005 (MR of 7.7), and non-mutagenic in TA102. These results showed a preferential sensitivity to reversion of the -CCC-target in TA100 and TA1535, and a lack of sensitivity to reversion of the -TAA-target in TA102. In addition, they elucidated the selectivity of the Ames II strains, with AT targets showing little or no sensitivity to reversion. The TE-epoxide derivative DEB was mutagenic in TA1535 and TA7004, but in contrast to TE, DEB was mutagenic in TA102. Interestingly, TA102 was reverted by DEB and H(2)O(2) but not by TE or DeaNO. This study showed that analysis of mutations is achievable using the battery of strains listed above. The fact that DNA damage can be detected by reversion at specific bases offers a tool for understanding the mechanisms through which drugs may exert their DNA and cellular damage.
Insights
This study compared mutation spectra of diethylamine NONOate (DeaNO) and treosulphan (TE) using Salmonella reversion assays. Results reveal differential mutagenicity and target selectivity, aiding in understanding drug-induced DNA damage mechanisms.
Area of Science:
- Toxicology
- Genetics
- Molecular Biology
Background:
- Nitric oxide (NO)-delivery drugs like diethylamine NONOate (DeaNO) and chemotherapeutics such as treosulphan (TE) are known mutagens.
- Understanding the specific mutations induced by these agents is crucial for assessing their genotoxic risk.
Purpose of the Study:
- To compare the mutation spectra induced by DeaNO and TE in various Salmonella strains.
- To investigate the mutagenicity of treosulphan's hydrolysis product, 1,2:3,4-diepoxybutane (DEB), and hydrogen peroxide (H(2)O(2)).
- To elucidate the DNA damage detection capabilities of a battery of Ames II strains.
Main Methods:
- Utilized Salmonella reversion assays with hisG46 strains (TA1535, TA100), hisG428 strain (TA102), and Ames II 7000 series strains.
- Administered DeaNO, TE, DEB, and H(2)O(2) to bacterial strains to assess induced mutations.
- Analyzed mutation spectra without DNA amplification or sequencing.
Main Results:
- TE and DeaNO showed preferential mutagenicity in TA1535 and TA100, targeting the -CCC- sequence, while TA102 (-TAA- target) was insensitive.
- Ames II strains exhibited selectivity, with AT targets showing limited reversion.
- DEB, unlike TE, was mutagenic in TA102, similar to H(2)O(2), suggesting distinct damage mechanisms.
Conclusions:
- The study demonstrates the utility of specific Salmonella strains for rapid analysis of drug-induced mutations.
- Differential mutagenicity and target site reversion provide insights into the mechanisms of genotoxicity for DeaNO, TE, and DEB.
- This approach offers a valuable tool for understanding how drugs cause DNA and cellular damage.
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