Quantitative relationship between ethylated DNA bases and gene mutation at two loci in CHO cells
- 1 January 1993
- journal article
- research article
- Published by Wiley in Environmental and Molecular Mutagenesis
- Vol. 21 (2) , 154-159
- https://doi.org/10.1002/em.2850210209
Abstract
In a previous study we showed that the formation of O6‐ethylguanine (O6‐EtGua) in the DNA of CHO cells in culture correlated with mutations induced by ethylnitrosourea (ENU) and diethylsulfate (DES) at the hypoxanthine‐guanine‐phosphoribosyltransferase (hprt) locus but not at the Na, K‐ATPase locus. This study was extended to another ethylating agent, ethyl methanesulfonate (EMS). DNA adduct formation and induction of mutation at the two gene loci were determined simultaneously in CHO cells after EMS exposure. The extent of ethylation at the N7 and O6 positions of guanine and at the N3 site of adenine were measured and the possible correlations with 6‐thioguanine resistance (6‐TGr) and ouabain resistance (ouar) mutations were investigated. A good correlation between the levels of ethylation at O6 guanine and mutation frequency at hprt gene by all three ethylating agents was observed. In the case of the ouar locus, the frequency of O6‐EtGua adducts correlated with mutation induction by EMS and ENU but not by DES. Although both EMS and DES have similar reaction mechanisms, these results highlight differences in their mutational specificity. The comparison of this type of analysis with mutational spectra revealed that correlation studies may be inadequate to analyse multi‐component phenomena like mutation formation.Keywords
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