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Development and characterization of hydrogen peroxide-resistant chinese hamster ovary cell variants—I:Relationship between catalase activity and the induction/stability of the oxidant-resistant phenotype

Authors
Journal
Biochemical Pharmacology
0006-2952
Publisher
Elsevier
Publication Date
Volume
45
Issue
11
Identifiers
DOI: 10.1016/0006-2952(93)90196-4
Disciplines
  • Biology

Abstract

Abstract Hydrogen peroxide (H 2O 2)-resistant sublines of Chinese hamster ovary (CHO) cells were isolated by in vitro exposure to the oxidant (treatment for 1 hr followed by 3 days of growth in peroxidefree medium). Stepwise increase in low lev progressively more resistant to the growth inhibitory effect elicited by the oxidant. Removal from H 2O 2 decreased resistance and the curve describing this process was biphasic in nature. In addition, the rate of loss of the H 2O 2-resistant phenotype was more rapid for the toxicity elicited by low concentrations of hydrogen peroxide, compared to that produced by high concentrations. Changes in total cell proteins were found to parallel the variations in sensitivity to the oxidant, since the protein content constantly increased during the adaptation process and decreases upon removal from H 2O 2. Catalase activity did not show large variations in resistant sublines with respect to the parental cell line, and these changes were at least partially related to differences in cell size/amount of total cell proteins of the sublines. In addition, the minor changes observed for catalase activity did not correlate with the degree of resistance to growth inhibition elicited by the oxidant. It may therefore be suggested that the H 2O 2-resistant phenotype of mammalian cells, initially adapted to low—then gradually increased—concentrations of the oxidant, is the result of a complex phenomenon which only partially involves over-expression of catalase.

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