Modulation of repair of ultraviolet damage in the host-cell reactivation assay by polymorphic XPC and XPD/ERCC2 genotypes

DNA repair capacity (DRC) plays an important role in genetic susceptibility to cancer. Polymorphisms of a number of DNA repair genes involved in several distinct pathways have been identified. However, their effects on repair function have not been well characterized. We demonstrated previously that DRC for removal of benzo[a]pyrene diol epoxide-induced DNA damage measured by a host-cell reactivation assay was modulated by two XPD/ERCC2 polymorphisms in lung cancer. In this report, we investigated the association between the repair phenotype of ultraviolet (UV)-induced damage and genotypes of three DNA repair genes, XPC and XPD [involved in nucleotide excision repair (NER)] and XRCC1 [involved in base excision repair (BER)]. We measured DRC for removal of UV photoproducts by the host-cell reactivation assay in cryopreserved lymphocytes from 102 healthy non-Hispanic white subjects. We also typed these subjects for five polymorphisms in these three DNA repair genes (at intron 9 of XPC; exons 6, 10 and 23 of XPD and exon 10 of XRCC1). Compared with wild-type homozygotes, subjects homozygous for polymorphisms of the two NER genes consistently had suboptimal DRC. The DRC was consistently lower in subjects homozygous for XPC, XPD or both than in subjects with other genotypes, although the difference was not statistically significant for XPD variants. In contrast, the polymorphic allele of the BER gene, XRCC1, had no consistent effect on DRC. We concluded that these NER polymorphisms may modulate DRC and may be useful biomarkers for identifying individuals at risk of developing cancer.