Mice without a functional OGG1 gene have about a 5-fold increased level of 8-oxo-dG in their livers compared to mice with wild-type OGG1.
 Mice defective in OGG1 also have an increased risk for cancer.
Kunisada et al.
irradiated mice without a functional OGG1 gene (OGG1 knock-out mice) and wild-type mice three times a week for forty weeks with UVB light at a relatively low dose (not enough to cause skin redness).
 Both types of mice had high levels of 8-oxo-dG in their epidermal cells three hours after irradiation.
 However, 24 hours later, the majority of 8-oxo-dG was absent from the epidermal cells of the wild-type mice but 8-oxo-dG remained elevated in the epidermal cells of the OGG1 knock-out mice.
 The irradiated OGG1 knock-out mice had more than twice the level of skin tumors compared to irradiated wild-type mice, and the rate of malignancy within the tumors was higher in the OGG1 knock-out mice (73%) than in the wild-type mice (50%).

As reviewed by Valavanidis et al.,
increased levels of 8-oxo-dG in a tissue can serve as a biomarker of oxidative stress.
 They also noted that increased levels of 8-oxo-dG are frequently found during carcinogenesis.

In the figure showing examples of mouse colonic epithelium, the colonic epithelium from a mouse on a normal diet was found to have a low level of 8-oxo-dG in its colonic crypts (panel A).
 However, a mouse likely undergoing colonic tumorigenesis (due to deoxycholate added to its diet) was found to have a high level of 8-oxo-dG in its colonic epithelium (panel B).
Deoxycholate increases intracellular production of reactive oxygen resulting in increased oxidative stress,> and this can lead to tumorigenesis and carcinogenesis.
Mice without a functional OGG1 gene have about a 5-fold increased level of 8-oxo-dG in their livers compared to mice with wild-type OGG1.  Mice defective in OGG1 also have an increased risk for cancer. Kunisada et al. irradiated mice without a functional OGG1 gene (OGG1 knock-out mice) and wild-type mice three times a week for forty weeks with UVB light at a relatively low dose (not enough to cause skin redness).  Both types of mice had high levels of 8-oxo-dG in their epidermal cells three hours after irradiation.  However, 24 hours later, the majority of 8-oxo-dG was absent from the epidermal cells of the wild-type mice but 8-oxo-dG remained elevated in the epidermal cells of the OGG1 knock-out mice.  The irradiated OGG1 knock-out mice had more than twice the level of skin tumors compared to irradiated wild-type mice, and the rate of malignancy within the tumors was higher in the OGG1 knock-out mice (73%) than in the wild-type mice (50%).
As reviewed by Valavanidis et al., increased levels of 8-oxo-dG in a tissue can serve as a biomarker of oxidative stress.  They also noted that increased levels of 8-oxo-dG are frequently found during carcinogenesis.
In the figure showing examples of mouse colonic epithelium, the colonic epithelium from a mouse on a normal diet was found to have a low level of 8-oxo-dG in its colonic crypts (panel A).  However, a mouse likely undergoing colonic tumorigenesis (due to deoxycholate added to its diet) was found to have a high level of 8-oxo-dG in its colonic epithelium (panel B). Deoxycholate increases intracellular production of reactive oxygen resulting in increased oxidative stress,> and this can lead to tumorigenesis and carcinogenesis.
Oxoguanine glycosylase