title: Slow repair of lipid peroxidation-induced DNA damage at p53 mutation hotspots in human cells caused by low turnover of a DNA glycosylase.
abstract: Repair of oxidative stress- and inflammation-induced DNA lesions by the base excision repair (BER) pathway prevents mutation, a form of genomic instability which is often observed in cancer as 'mutation hotspots'. This suggests that some sequences have inherent mutability, possibly due to sequence-related differences in repair. This study has explored intrinsic mutability as a consequence of sequence-specific repair of lipid peroxidation-induced DNA adduct, 1, N(6)-ethenoadenine (εA). For the first time, we observed significant delay in repair of ϵA at mutation hotspots in the tumor suppressor gene p53 compared to non-hotspots in live human hepatocytes and endothelial cells using an in-cell real time PCR-based method. In-cell and in vitro mechanism studies revealed that this delay in repair was due to inefficient turnover of N-methylpurine-DNA glycosylase (MPG), which initiates BER of εA. We determined that the product dissociation rate of MPG at the hotspot codons was ≈5-12-fold lower than the non-hotspots, suggesting a previously unknown mechanism for slower repair at mutation hotspots and implicating sequence-related variability of DNA repair efficiency to be responsible for mutation hotspot signatures.
authors: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical School, Washington, DC 20057, USA.
authors: Jordan
authors: J
authors: Woodrick
authors: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical School, Washington, DC 20057, USA.
authors: Suhani
authors: S
authors: Gupta
authors: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical School, Washington, DC 20057, USA.
authors: Pooja
authors: P
authors: Khatkar
authors: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical School, Washington, DC 20057, USA.
authors: Sanchita
authors: S
authors: Sarangi
authors: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical School, Washington, DC 20057, USA.
authors: Ganga
authors: G
authors: Narasimhan
authors: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical School, Washington, DC 20057, USA.
authors: Akriti
authors: A
authors: Trehan
authors: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical School, Washington, DC 20057, USA.
authors: Sanjay
authors: S
authors: Adhikari
authors: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical School, Washington, DC 20057, USA rr228@georgetown.edu.
authors: Rabindra
authors: R
authors: Roy
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D004249:DNA Damage; D045647:DNA Glycosylases / Q000378:metabolism*; D004260:DNA Repair; D042783:Endothelial Cells / Q000378:metabolism; D016158:Genes, p53; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D015227:Lipid Peroxidation; D051379:Mice; D009154:Mutation; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods
chemical_list: C004981:1,N(6)-ethenoadenine; D045647:DNA Glycosylases; C076131:DNA-3-methyladenine glycosidase II; D000225:Adenine