An association between BPDE-like DNA adduct levels and P53 gene mutation in pterygium

Purpose: A previous report of ours noted that not only p53 protein overexpression, but also p53 gene mutation. were indeed detected in pterygium. BaP 7,8-diol 9,10-epoxide (BPDE), an ultimate metabolite of BaP, attacks deoxyguanosine to form a BPDE-N2-dG adduct resulting in p53 mutations. The relationship between BPDE-like DNA adduct levels and abnormal p53 has not been clear in pterygium. Therefore, BPDE-like DNA adduct, p53 protein expression and p53 gene mutation were examined in this study to provide more molecular evidence to understand the cause of p53 gene mutation in pterygium. Methods: In this study, immunohistochemical staining, using a monoclonal antibody (DO7) against p53 and a polyclonal antibody against BPDE-like DNA adducts, was performed on 73 pterygial specimens. DNA samples for p53 mutation analysis were extracted from epithelial cells and then subjected to DNA sequencing for the determination of mutations in exons 4, 5, 6, 7, and 8 of the p53 gene. Results: BPDE-like DNA adducts were detected in 36.1% (26/73) pterygium samples. No correlation between adduct levels and p53 protein expression was found in these samples. Additionally, the p53 gene mutation and p53 mutation pattern also did not correlate with BPDE-like DNA adduct levels. Conclusions: Our data provides evidence that BPDE-like DNA adducts are indeed detected in pterygium samples, and they are only minor contributors to the abnormal p53 gene.