Base excision repair (BER) is considered the most important pathway involved in removing DNA damage. Base excision repair pathway is initiated by recognition of a DNA glycosylase (OGG1-oxoguanine glycosylase 1 and MUTYH -MutY homolog)/. This glycosylase catalyzes the cleavage of an N-glycosidic bond, effectively removing the damaged base The DNA backbone is cleaved by a DNA AP endonuclease/APE1/ and creating an apurinic or apyrmidinic site (AP site). DNA polymeraseX-ray repair cross-complementing group 1(XRCC1) fills in the gap with the correct nucleotide. Finally, DNA ligase completes the repair process and restores the integrity of the helix by sealing the nick. Many genes encoding DNA damage repair proteins involved in BER are highly polymorphic. Those polymorphisms have a great influence on pertinent protein functions and they are associated with individual susceptibility into neoplastic events. XRCC1 plays an important role in BER system, which is critical for genome maintenance. Polymorphisms in XRCC1 that result alteration of DNA repair capacity are reportedly associated with cancer risk and treatment response.
Batchimeg Norjmaa, Khosbayar Tulgaa and Takayuki Saitoh