A Fatal Combination: A Thymidylate Synthase Inhibitor with DNA Damaging Activity

Abstract

2′-deoxy-5-ethynyluridine (EdU) has been previously shown to be a cell poison whose toxicity depends on the particular cell line. The reason is not known. Our data indicates that different efficiency of EdU incorporation plays an important role. The EdU-mediated toxicity was elevated by the inhibition of 2′-deoxythymidine 5′-monophosphate synthesis. EdU incorporation resulted in abnormalities of the cell cycle including the slowdown of the S phase and a decrease in DNA synthesis. The slowdown but not the cessation of the first cell division after EdU administration was observed in all of the tested cell lines. In HeLa cells, a 10 μM EdU concentration led to the cell death in the 100% of cells probably due to the activation of an intra S phase checkpoint in the subsequent S phase. Our data also indicates that this EdU concentration induces interstrand DNA crosslinks in HeLa cells. We suppose that these crosslinks are the primary DNA damage resulting in cell death. According to our results, the EdU-mediated toxicity is further increased by the inhibition of thymidylate synthase by EdU itself at its higher concentrations.

Investigation of pyrimidine nucleoside analogues as chemical probes to assess compound effects on the proliferation of Trypanosoma cruzi intracellular parasites

“…The inhibitory activity exhibited by EdU against HEK293 cells and T. cruzi has been similarly shown for a number of cell lines both in vivo and in vitro [30,31]. For example, it has been demonstrated that following 72 hours exposure of HEK293 cells to EdU there was cytotoxicity displayed, with an IC 50 value of 0.060 ± 0.043 μM identified [32].…”

“…Some strains used by Sánchez-Valdéz et al were transfected with pTREX-Luciferase/ TdTomato and it would be of benefit to compare with wild type parasites. The impact of EdU causing time dependant inhibition of cell growth on various mammalian cell lines is well documented [52,53]. In the studies herein, exposure of EdU was limited to 2 or 4 hours incubation.…”

“…It would be advantageous to understand in more detail the replication of T. cruzi parasites during the chronic stage of the disease, with probes which may exhibit less parasite growth inhibition. Next generation chemical probes with improved properties will increase the potential for studying DNA synthesis and reduction of the inhibition of thymidylate synthase, mediated by EdU [53] and could reduce the effects of this compound on parasite growth.…”

Administration of a Nucleoside Analog Promotes Cancer Cell Death in a Telomerase-Dependent Manner

“…To explore whether similar effects were encountered with another nucleoside analog, we treated the five different cell lines with 5-ethynyl-2′-deoxyuridine (5-EdU). While 5-EdU is generally recognized by the replication complex to promote DNA damage and cytotoxicity in dividing cells (Ligasová et al, 2015), its nucleotide counterpart does not serve as an efficient substrate for telomerase-mediated extension (Figure 1). Indeed, administration of 5-EdU induced cell death in all treated cells, regardless of their telomerase status (Figure 2C).…”

The 1,10-Phenanthroline Ligand Enhances the Antiproliferative Activity of DNA-Intercalating Thiourea-Pd(II) and -Pt(II) Complexes Against Cisplatin-Sensitive and -Resistant Human Ovarian Cancer Cell Lines

“…In fact, the depletion of dTMP and subsequently dTTP induced perturbations in the levels of the other deoxynucleotides (dATP, dGTP, and dCTP), resulting in a reduction of the DNA synthesis and repair [39]. These effects suggest that a combinatorial strategy with our complexes and traditional TS inhibitors, such as 5-fluorouracil, raltitrexed or pemetrexed might have great potential in killing cells even with innated or more elevated TS levels that are more elevated [40].…”