An association between BPDE-like DNA adduct levels and P53 gene mutation in pterygium.
OBJECTIVE
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.
Lai
Te-Jen
TJ
Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan. graduate@csmu.edu.tw <graduate@csmu.edu.tw>
Tsai
Yi-Yu
YY
Cheng
Ya-Wen
YW
Chiang
Chun-Chi
CC
Lee
Huei
H
Chou
Ming-Chih
MC
Chang
Julia Hueimei
JH
D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide / Q000031:analogs & derivatives*; D000368:Aged; D000369:Aged, 80 and over; D018736:DNA Adducts / Q000378:metabolism*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000235:genetics; D005260:Female; D016158:Genes, p53; D006147:Guanine; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011625:Pterygium / Q000235:genetics* / Q000378:metabolism*; D013194:Staining and Labeling; D013941:Thymine; D014018:Tissue Distribution; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D018736:DNA Adducts; D016159:Tumor Suppressor Protein p53; D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; D006147:Guanine; C040060:7,8-dihydroxy-9,10-epoxide-7,8,9,10-tetrahydrobenzo(a)pyrene-10-deoxyguanosine; D003849:Deoxyguanosine; D013941:Thymine