Cytokinesis-block micronucleus assay of celecoxib and celecoxib derivatives

Reimann, Hauke; Ngo, Quoc Anh; Stopper, Helga; Hintzsche, Henning

doi:10.1016/j.toxrep.2020.11.004

Cited by 1 publication

(1 citation statement)

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“…According to the authors, lysosomal enzymes may be involved in the fragmentation of micronuclear DNA after fusion of lysosomes and micronuclei, which was observed as well (Maass et al 2018 ). Autophagy of the main nucleus and the micronucleus was furthermore described in yeast as essential step of autophagy (Otto and Thumm 2020 ). Recent publications revealed that cGAS (cyclic GMP-AMP synthase), a sensor of cytosolic DNA and mediator of immune response, can interact with LC3 and degrade micronuclei by autophagy (Zhao et al 2021 ).…”

Section: Discussionmentioning

confidence: 99%

Fate of micronuclei and micronucleated cells after treatment of HeLa cells with different genotoxic agents

2022

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Although micronuclei are well-known biomarkers of genotoxic damage, the biological consequences of micronucleus induction are only poorly understood. To further elucidate these consequences, HeLa cells stably expressing histone 2B coupled with green fluorescent protein were used for long-term live cell imaging to investigate the fate of micronuclei and micronucleated cells after treatment of cells with various genotoxic agents (doxorubicin (20, 30 and nM), tert-butyl hydroperoxide (tBHP, 50, 100 and 150 µM), radiation (0.5, 1 and 2 Gy), methyl methanesulfonate (MMS, 20, 25 and 30 µg/ml) and vinblastine (1, 2 and 3 nM)). Most micronuclei persist for multiple cell cycles or reincorporate while micronucleated cells were more prone to cell death, senescence and fatal mitotic errors compared to non-micronucleated cells, which is consistent with previous studies using etoposide. No clear substance-related effects on the fate of micronuclei and micronucleated cells were observed. To further investigate the fate of micronuclei, extrusion of micronuclei was studied with treatments reported as inducing the extrusion of micronuclei. Since extrusion was not observed in HeLa cells, the relevance of extrusion of micronuclei remains unclear. In addition, degradation of micronuclei was analysed via immunostaining of γH2AX, which demonstrated a high level of DNA damage in micronuclei compared to the main nuclei. Furthermore, transduction with two reporter genes (LC3B-dsRed and LaminB1-dsRed) was conducted followed by long-term live cell imaging. While autophagy marker LC3B was not associated with micronuclei, Lamin B1 was found in approximately 50% of all micronuclei. While degradation of micronuclei was not observed to be a frequent fate of micronuclei, the results show impaired stability of DNA and micronuclear envelope indicating rupture of micronuclei as a pre-step to chromothripsis.

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Section: Discussionmentioning

confidence: 99%