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Molecular analysis of hprt mutations generated in Chinese hamster ovary EM9 cells by uranyl acetate, by hydrogen peroxide, and spontaneously
Author(s) -
Coryell Virginia H.,
Stearns Diane M.
Publication year - 2005
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/mc.20155
Subject(s) - biology , hypoxanthine guanine phosphoribosyltransferase , chinese hamster ovary cell , uranyl acetate , mutant , microbiology and biotechnology , hypoxanthine , mutagenesis , genetics , biochemistry , gene , cell culture , enzyme , staining
Naturally occurring uranium and depleted uranium (DU) are believed to be health hazards by virtue of both their chemical and radiological properties. The mechanism(s) behind uranium's chemotoxic effects has yet to be elucidated. Previous work has shown that DU, as uranyl acetate (UA), was mutagenic at the hypoxanthine (guanine) phosphoribosyltransferase ( hprt ) locus in XRCC1‐deficient CHO EM9 cells. The purpose of the current study was to characterize the mutations induced by UA at the hprt locus of CHO EM9 cells and compare the mutation spectrum of UA with those of hydrogen peroxide and spontaneous mutations in the same line. The hypothesis being tested was that if DU as UA is chemically genotoxic then the mutation spectrum induced by the heavy metal should be distinct from that produced spontaneously or by H 2 O 2 . A total of 59 UA‐induced, 38 spontaneous, and 45 H 2 O 2 ‐induced mutations were identified. Base substitutions comprised 29%, 42%, and 16% of UA, spontaneous, and H 2 O 2 mutants, respectively. The frequency of G → T or C → A substitutions was not significantly different in spontaneous or H 2 O 2 ‐induced mutants than in UA‐induced mutants, suggesting a possible role for 8‐oxodG damage in UA mutagenesis. However, the observation that UA produced significantly more major genomic rearrangements (multiexon insertions and deletions) than occurred spontaneously suggests the possibility that DNA strand breaks or crosslinks could also be UA‐induced mutagenic lesions. The unique mutation spectrum elicited by exposure to UA suggests that UA generates mutations in ways that are different from spontaneous and free radical as well as radiological mechanisms. © 2005 Wiley‐Liss, Inc.