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A novel signature mutation for oxidative damage resembles a mutational pattern found commonly in human cancers
M S Turker1, B M Gage, J A Rose
1Center for Research on Occupational and Environmental Toxicology, Oregon Health Sciences University, Portland 97201, USA. turkerm@ohsu.edu
Abstract:
To determine the types of mutations induced by oxidative damage, a kidney cell line with a heterozygous deficiency for the autosomal Aprt (adenine phosphoribosyltransferase) gene was tested for its mutagenic response to hydrogen peroxide. Aprt-deficient cells were selected and scored for loss of heterozygosity (LOH) for 11 microsatellite loci on mouse chromosome 8. On the basis of the LOH analysis, spontaneous mutants (n = 38) were distributed into four classes: apparent point mutation, mitotic recombination, chromosome loss, and large interstitial deletion. However, 9 of 20 (45%) hydrogen peroxide-induced mutants exhibited a novel class of mutations characterized by "discontinuous LOH" for one or more of the microsatellite loci. Interestingly, mutations resembling discontinuous LOH are commonly observed in a wide variety of human cancers. Our data suggest that discontinuous LOH is a signature mutational pattern for oxidative damage and further suggest that such genetic damage is widespread in cancer.
Insights
Oxidative damage from hydrogen peroxide induces unique "discontinuous loss of heterozygosity" mutations in kidney cells. This novel mutation pattern is linked to various human cancers, suggesting its widespread role in cancer development.
Area of Science:
- Genetics
- Molecular Biology
- Cancer Research
Background:
- Oxidative damage is implicated in various diseases, including cancer.
- Understanding mutation types induced by oxidative stress is crucial for cancer research.
- The adenine phosphoribosyltransferase (Aprt) gene is a key player in DNA repair and mutation studies.
Purpose of the Study:
- To investigate the specific types of mutations induced by oxidative damage.
- To characterize the mutagenic response of kidney cells to hydrogen peroxide.
- To determine if "discontinuous loss of heterozygosity" is a signature of oxidative damage.
Main Methods:
- Utilized a heterozygous kidney cell line deficient in the autosomal Aprt gene.
- Exposed cells to hydrogen peroxide to induce oxidative damage.
- Analyzed spontaneous and induced mutants for loss of heterozygosity (LOH) at 11 microsatellite loci on mouse chromosome 8.
Main Results:
- Spontaneous mutants showed four classes: point mutation, mitotic recombination, chromosome loss, and large interstitial deletion.
- A novel mutation class, "discontinuous LOH," was observed in 45% of hydrogen peroxide-induced mutants.
- Discontinuous LOH involved one or more microsatellite loci and is frequently seen in human cancers.
Conclusions:
- Discontinuous LOH is a distinct mutational pattern specifically induced by oxidative damage.
- This finding suggests oxidative damage plays a significant role in the genetic alterations observed in cancer.
- The study highlights the potential widespread impact of oxidative genetic damage in human cancers.