Increased mutability and decreased repairability of a three-lesion clustered DNA-damaged site comprised of an AP site and bi-stranded 8-oxoG lesions.

Purpose: Ionizing radiation induces DNA damage, some of which are present in clusters, defined as two or more lesions within one to two helical turns of DNA by passage of a single radiation track. These clusters are thought to contribute to the detrimental effects of radiation, in part due to the compromised repair of clustered DNA damaged sites.

Materials And Methods: The repair of three-lesion cluster present in oligonucleotides were determined in vitro using the hamster cell line CHO-K1 nuclear extract or purified proteins involved in base excision repair.