Evidence of erythropoiesis rather than direct genotoxicity causing micronucleus induction by a new protoporphyrinogen-oxidase inhibitor

IF 2.8 4区医学 Q3 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Mutation research. Genetic toxicology and environmental mutagenesis Pub Date : 2025-10-01 Epub Date: 2025-10-02 DOI:10.1016/j.mrgentox.2025.503900

Naveed Honarvar , Astrid Zander , Miyuki Shigano , Eva Dony , Brandy Riffle , Markus Frericks , Tobias Seiser , Robert Landsiedel

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引用次数: 0

Abstract

Protoporphyrinogen-oxidase inhibitors (PPOi) are a class of herbicides that target chlorophyll synthesis in plants. Similarly, they affect heme synthesis in mammals, resulting in anemia. A new PPOi development candidate showed micronucleus formation in the bone marrow of rodents in vivo. Increased erythropoiesis has previously been described to increase micronucleus formation in the bone marrow. Hence, the micronuclei (MN) observed after administration of the new PPOi candidate may be caused by increased erythropoiesis rather than direct genotoxicity. To investigate this, the mutagenicity in vitro was examined and found to be clearly negative. In addition, micronucleus formation in vivo was investigated after administration of the new PPOi in doses that caused anemia. Both, erythropoietic and non-erythropoietic tissues, bone marrow and liver, were investigated. Moreover, genotoxicity was investigated by the Comet-assay in erythroid and non-erythroid cells of the bone marrow. The new PPOi did not show mutagenic effects in vitro. The new PPOi induced an increase in the micronucleus counts in the bone marrow of rats, whereas the hepatocytes were not affected. In another study in mice, micronucleus formation was observed in the new PPOi-exposed bone marrow. In parallel, bone marrow cells of the same animals were separated into subpopulations isolating erythroid (selected via their Ter119 surface marker) and non-erythroid (selected by their CD45 surface marker) cells, which were then assessed in a comet assay. Results showed a dose dependent increase in micronucleus frequencies while, increases in % DNA tail intensities in the comet assay were only observed in the erythroid Ter119⁺ subpopulation, but not in non-erythroid bone marrow cells. This provides evidence that the new PPOi induces MN only upon induction of anemia, and that the DNA-damage is only occurring in erythroid cells. The increased micronucleus-formation of the new PPOi in vivo is hence most likely caused by erythropoiesis and not by direct genotoxic actions.

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一种新的原卟啉氧化酶抑制剂引起微核诱导的证据是红细胞生成而不是直接的遗传毒性

原卟啉原氧化酶抑制剂（PPOi）是一类以植物叶绿素合成为目标的除草剂。同样，它们影响哺乳动物的血红素合成，导致贫血。一种新的PPOi开发候选物在啮齿类动物体内骨髓中显示微核形成。红细胞生成的增加以前被描述为增加骨髓中微核的形成。因此，服用新的PPOi候选药物后观察到的微核（MN）可能是由于红细胞生成增加而不是直接的遗传毒性引起的。为了研究这一点，在体外进行了诱变性检查，发现明显阴性。此外，研究了新PPOi引起贫血的剂量给药后体内微核形成的情况。红细胞和非红细胞组织，骨髓和肝脏，都进行了研究。此外，通过Comet-assay对骨髓红系和非红系细胞进行遗传毒性研究。新的PPOi在体外没有表现出诱变作用。新PPOi诱导大鼠骨髓微核计数增加，而肝细胞不受影响。在另一项小鼠研究中，在暴露于ppoi的新骨髓中观察到微核形成。同时，将同一动物的骨髓细胞分离为分离红系细胞（通过Ter119表面标记选择）和非红系细胞（通过CD45表面标记选择）的亚群，然后在彗星试验中进行评估。结果显示微核频率呈剂量依赖性增加，而彗星试验中% DNA尾部强度的增加仅在红系Ter119+亚群中观察到，而在非红系骨髓细胞中没有观察到。这提供了新的PPOi仅在诱导贫血时诱导MN的证据，并且dna损伤仅发生在红系细胞中。因此，体内新PPOi微核形成的增加很可能是由红细胞生成引起的，而不是由直接的遗传毒性作用引起的。

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来源期刊

Mutation research. Genetic toxicology and environmental mutagenesis 生物-毒理学

CiteScore

3.80

自引率

5.30%

发文量

审稿时长

105 days

期刊介绍： Mutation Research - Genetic Toxicology and Environmental Mutagenesis (MRGTEM) publishes papers advancing knowledge in the field of genetic toxicology. Papers are welcomed in the following areas: New developments in genotoxicity testing of chemical agents (e.g. improvements in methodology of assay systems and interpretation of results). Alternatives to and refinement of the use of animals in genotoxicity testing. Nano-genotoxicology, the study of genotoxicity hazards and risks related to novel man-made nanomaterials. Studies of epigenetic changes in relation to genotoxic effects. The use of structure-activity relationships in predicting genotoxic effects. The isolation and chemical characterization of novel environmental mutagens. The measurement of genotoxic effects in human populations, when accompanied by quantitative measurements of environmental or occupational exposures. The application of novel technologies for assessing the hazard and risks associated with genotoxic substances (e.g. OMICS or other high-throughput approaches to genotoxicity testing). MRGTEM is now accepting submissions for a new section of the journal: Current Topics in Genotoxicity Testing, that will be dedicated to the discussion of current issues relating to design, interpretation and strategic use of genotoxicity tests. This section is envisaged to include discussions relating to the development of new international testing guidelines, but also to wider topics in the field. The evaluation of contrasting or opposing viewpoints is welcomed as long as the presentation is in accordance with the journal''s aims, scope, and policies.