Induction of sister-chromatid exchanges in Chinese hamster ovary cells by thiol and hydrazine compoudns
Macrae, W.D.; Stich, H.F.
Mutation Research 68(4): 351-365
1979
ISSN/ISBN: 0027-5107 PMID: 522883 Document Number: 149857
Cysteine, cysteamine and glutathione all induce sister chromatid exchanges (SCE) in Chinese hamster ovary (CHO) cells when applied to cell cultures at concentrations between 10-4 and 10-2 M. Acute exposure of cells to thiol compound for 2-3 h resulted in a unique dose.sbd.response relationship in each instance. This consisted of 2 peak SCE frequencies, one at either extreme of the concentration range. Each peak corresponded to a 2- to 3-fold increase over the spontaneous level. A chronic exposure of 24 h resulted in a dose.sbd.response relationship consisting of a single peak SCE frequency (representing a 4- to 5-fold increase over the spontaneous level) at a concentration of .apprx. 4 .times. 10-4 M. The effect of Cu2+ included in the medium at a concentration of 10-5 M was to increase the toxicity and, at some concentrations, the SCE levels occurring after either acute or chronic exposure to thiols. Hydrazine and its derivatives, dimethylhydrazine and isonicotinic acid hydrazide (isoniazid), and H2O2 also induce SCE in CHO cells. A 2- to 3-fold increase over the spontaneous level was observed, depending upon the particular treatment protocol applied. SCE yields after 3 h treatment with dimethylhydrazine and isoniazid were increased if Mn2+, but not Cu2+, was included in the tissue culture medium at a concentration of 10-5 M. SCE yields after a 24-h treatment with dimethylhydrazine in which Mn2+ was present in, and absent from, the medium were similar. Catalase reduced the SCE levels resulting from treatment with H2O2, dimethylhydrazine and isoniazid. The effect of catalase upon SCE induced by dimethylhydrazine and isoniazid in the presence of Mn2+ was more evident than when Mn2+ was not included in the culture medium. The significance of these results with respect to the possible active chemical species produced and the mutagenic/carcinogenic risk associated with thiol and hydrazine compounds is discussed. (Human applicability is implied.).