Evaluating the Genotoxic and Cytotoxic Effects of Thymidine Analogs, 5-Ethynyl-2'-Deoxyuridine and 5-Bromo-2'-Deoxyurdine to Mammalian Cells.

Jeremy S Haskins,Coral E Froning,Cathy Su,Kade D Walsh,Takamitsu A Kato,Junko Maeda,Alexis H Haskins,Allison J Allum

doi:10.3390/ijms21186631

Jeremy S Haskins, Coral E Froning + Show 6 more

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https://doi.org/10.3390/ijms21186631

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Abstract

BrdU (bromodeoxyuridine) and EdU (ethynyldeoxyuridine) have been largely utilized as the means of monitoring DNA replication and cellular division. Although BrdU induces gene and chromosomal mutations and induces sensitization to photons, EdU‘s effects have not been extensively studied yet. Therefore, we investigated EdU’s potential cytotoxic and mutagenic effects and its related underlying mechanisms when administered to Chinese hamster ovary (CHO) wild type and DNA repair-deficient cells. EdU treatment displayed a higher cytotoxicity and genotoxicity than BrdU treatment. Cells with defective homologous recombination repair displayed a greater growth delay and severe inhibition of clonogenicity with EdU compared to wild type and other DNA repair-deficient cells. Inductions of sister chromatid exchange and hypoxanthine phosphorybosyl transferase (HPRT) mutation were observed in EdU-incorporated cells as well. Interestingly, on the other hand, EdU did not induce sensitization to photons to the same degree as BrdU. Our results demonstrate that elevated concentrations (similar to manufacturers suggested concentration; >5–10 μM) of EdU treatment were toxic to the cell cultures, particularly in cells with a defect in homologous recombination repair. Therefore, EdU should be administered with additional precautions.

Highlights

BrdU (Bromodeoxyuridine) has been utilized as a primary means of labeling actively dividing cells
Nearly a 1000-fold in survival fraction in cells treated with EdU and absence of nucleotide/nucleoside (Figure 1a,b)
Our study showed that EdU induces an unavoidable amount of sister chromatid exchange (SCE) (Figure 4)

Summary

Introduction

BrdU (Bromodeoxyuridine) has been utilized as a primary means of labeling actively dividing cells. EdU (Ethynyldeoxyuridine) has developed popularity as a rapid and effective biochemical agent for detection of DNA synthesis [1,2,3]. EdU was first demonstrated to monitor and detect replicational activity in 2008 [2]. EdU has additional quantifiable and qualitative applications such as apoptosis detection [4], Raman spectroscopy [5,6], viral/bacterial inactivation [7], the DNA fiber assay [8], and sister chromatid exchange (SCE) assay [9,10,11]. 105 cells.breaks cells didany notcytotoxicity show statistically significant increases. EdU,treatment there was a recognizable formation was65observed with treatment

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