The formamidopyrimidine DNA glycosylase (Fpg)-modified comet assay is widely used for the measurement of oxidatively generated damage to DNA. However, there has not been a recommended long-term positive control for this version of the comet assay. We have investigated potassium bromate as a positive control for the Fpg-modified comet assay because it generates many Fpg-sensitive sites with a little concurrent generation of DNA strand breaks. Eight laboratories used the same procedure for the treatment of monocytic THP-1 cells with potassium bromate (0, 0.5, 1.5, and 4.5 mM) and subsequent cryopreservation in a freezing medium consisting of 50% foetal bovine serum, 40% RPMI-1640 medium, and 10% dimethyl sulphoxide. The samples were analysed by the Fpg-modified comet assay three times over a 3-year period. All laboratories obtained a positive concentration-response relationship in cryopreserved samples (linear regression coefficients ranging from 0.79 to 0.99). However, there was a wide difference in the levels of Fpg-sensitive sites between the laboratory with the lowest (4.2% Tail DNA) and highest (74% Tail DNA) values in THP-1 cells after exposure to 4.5 mM KBrO3. In an attempt to assess sources of inter-laboratory variation in Fpg-sensitive sites, comet images from one experiment in each laboratory were forwarded to a central laboratory for visual scoring. There was high consistency between measurements of %Tail DNA values in each laboratory and the visual score of the same comets done in the central laboratory (r = 0.98, P < 0.001, linear regression). In conclusion, the results show that potassium bromate is a suitable positive comet assay control.

Long-term cryopreservation of potassium bromate positive assay controls for measurement of oxidatively damaged DNA by the Fpg-modified comet assay: results from the hCOMET ring trial / Møller, Peter; Azqueta, Amaya; Rodriguez-Garraus, Adriana; Bakuradze, Tamara; Richling, Elke; Bankoglu, Ezgi Eyluel; Stopper, Helga; Claudino Bastos, Victoria; Langie, Sabine A S; Jensen, Annie; Ristori, Sara; Scavone, Francesca; Giovannelli, Lisa; Wojewódzka, Maria; Kruszewski, Marcin; Valdiglesias, Vanessa; Laffon, Blanca; Costa, Carla; Costa, Solange; Paulo Teixeira, João; Marino, Mirko; Del Bo', Cristian; Riso, Patrizia; Zheng, Congying; Shaposhnikov, Sergey; Collins, Andrew. - In: MUTAGENESIS. - ISSN 0267-8357. - STAMPA. - 38:(2023), pp. 264-272. [10.1093/mutage/gead020]

Long-term cryopreservation of potassium bromate positive assay controls for measurement of oxidatively damaged DNA by the Fpg-modified comet assay: results from the hCOMET ring trial

Ristori, Sara;Scavone, Francesca;Giovannelli, Lisa;Riso, Patrizia;
2023

Abstract

The formamidopyrimidine DNA glycosylase (Fpg)-modified comet assay is widely used for the measurement of oxidatively generated damage to DNA. However, there has not been a recommended long-term positive control for this version of the comet assay. We have investigated potassium bromate as a positive control for the Fpg-modified comet assay because it generates many Fpg-sensitive sites with a little concurrent generation of DNA strand breaks. Eight laboratories used the same procedure for the treatment of monocytic THP-1 cells with potassium bromate (0, 0.5, 1.5, and 4.5 mM) and subsequent cryopreservation in a freezing medium consisting of 50% foetal bovine serum, 40% RPMI-1640 medium, and 10% dimethyl sulphoxide. The samples were analysed by the Fpg-modified comet assay three times over a 3-year period. All laboratories obtained a positive concentration-response relationship in cryopreserved samples (linear regression coefficients ranging from 0.79 to 0.99). However, there was a wide difference in the levels of Fpg-sensitive sites between the laboratory with the lowest (4.2% Tail DNA) and highest (74% Tail DNA) values in THP-1 cells after exposure to 4.5 mM KBrO3. In an attempt to assess sources of inter-laboratory variation in Fpg-sensitive sites, comet images from one experiment in each laboratory were forwarded to a central laboratory for visual scoring. There was high consistency between measurements of %Tail DNA values in each laboratory and the visual score of the same comets done in the central laboratory (r = 0.98, P < 0.001, linear regression). In conclusion, the results show that potassium bromate is a suitable positive comet assay control.
2023
38
264
272
Møller, Peter; Azqueta, Amaya; Rodriguez-Garraus, Adriana; Bakuradze, Tamara; Richling, Elke; Bankoglu, Ezgi Eyluel; Stopper, Helga; Claudino Bastos, Victoria; Langie, Sabine A S; Jensen, Annie; Ristori, Sara; Scavone, Francesca; Giovannelli, Lisa; Wojewódzka, Maria; Kruszewski, Marcin; Valdiglesias, Vanessa; Laffon, Blanca; Costa, Carla; Costa, Solange; Paulo Teixeira, João; Marino, Mirko; Del Bo', Cristian; Riso, Patrizia; Zheng, Congying; Shaposhnikov, Sergey; Collins, Andrew
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1334691
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