8-Oxoguanine (8-hydroxyguanine, 8-oxo-Gua, or OH8Gua) is one of the most common DNA lesions resulting from
reactive oxygen species[2] modifying
guanine, and can result in a mismatched pairing with
adenine resulting in G to T and C to A substitutions in the genome.[3] In humans, it is primarily repaired by
DNA glycosylaseOGG1. It can be caused by
ionizing radiation, in connection with
oxidative metabolism.
In body fluids
Increased concentrations of 8-oxoguanine in body fluids have been found to be associated with increased risk of
mutagenesis and
carcinogenesis.[4][5]
Care must be taken in the assay of 8-oxoguanine due to the ease with which it can be oxidised during extraction and the assay procedure.[6]
Cancer, aging, infertility
The role of the deoxyriboside form of 8-oxoguanine,
8-oxo-2'-deoxyguanosine (abbreviated 8-oxo-dG or 8-OHdG) in
cancer and
aging also applies to 8-oxoguanine.
Oxoguanine glycosylase is employed in the removal of 8-oxoguanine from
DNA by the process of
base excision repair. As described in
oxoguanine glycosylase, deficient expression of this enzyme causes 8-oxoguanine to accumulate in DNA. This accumulation may then lead upon replication of DNA to
mutations including some that contribute to
carcinogenesis. 8-oxoguanine is usually formed by the interaction of
reactive oxygen species (ROS) with the
guanine base in DNA under conditions of
oxidative stress; as noted in the article about them, such species may have a role in aging and male infertility, and 8-oxoguanine can be used to measure such stress.
^Kasai, H (December 1997). "Analysis of a form of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine, as a marker of cellular oxidative stress during carcinogenesis". Mutation Research. 387 (3): 147–63.
doi:
10.1016/s1383-5742(97)00035-5.
PMID9439711.
^Halliwell, B (December 1998). "Can oxidative DNA damage be used as a biomarker of cancer risk in humans? Problems, resolutions and preliminary results from nutritional supplementation studies". Free Radical Research. 29 (6): 469–86.
doi:
10.1080/10715769800300531.
PMID10098453.