p53 gene mutations in SKH-1 mouse tumors differentially induced by UVB and combined subcarcinogenic benzo[a]pyrene and UVA.
We compared the frequency and spectra of p53 mutations in skin tumors from UVB-irradiated and benzo(a)pyrene-UVA-treated SKH-1 mice. Analysis of p53 mutations using a combination of polymerase chain reaction, denaturing high-performance liquid chromatography, and sequencing shows that the frequency and spectrum of p53 mutations in BaP-UVA-induced tumors are quite different from those in UVB-induced tumors. SKH-1 mice were treated with BaP-UVA or UVB for 30 weeks after which skin tumors were collected for analysis of p53 mutations. Among the 11 BaP-UVA-induced tumors with diameters of 5-10 mm, two displayed mutations in exon 8 yielding a mutation frequency of 18.2%. In contrast, the mutation frequency among BaP-UVA-induced tumors was 10.5%. In UVB-induced tumors, the mutation frequency in exon 8 was highly correlated with tumor size. A total of 77.8% of tumors with diameters larger than 10 mm contained p53 mutations. The overall mutation frequency among UVB-induced tumors was 17.9% in exon 8 and only 3.8% in exon 5. Hotspots for p53 mutation in UVB-induced tumors were found at codons 128 and 149 (exon 5), and at codons 268, 270, 271 and 273-276 (exon 8). In addition to widely recognized C-->T missense mutations, there were also tandem CC-->AG changes coupled with either an insertion of T, a C-->G substitution or G-->C/T mutations. All of the mutations were found at tri- or tetra-pyrimidine sites. Thirty-nine per cent of all p53 mutations occurred at codons 274 and 275; 53% occurred at codons 268-271. Two multiple mutation clusters were located at codons 268-271 and 274-276. Both BaP-UVA and UVB caused C-->T transitions at codon 275 in exon 8. A C-->T mutation at codon 294 was induced only by BaP-UVA treatment. In contrast to UVB treatment, BaP-UVA treatment did not induce any mutations in exon 5. We show that individually subcarcinogenic levels of BaP and UVA synergistically induce a novel p53-mutation fingerprint. This fingerprint could serve as a prognostic indicator for the development of BaP-UVA-induced skin tumors.
Wang
Yongyin
Y
Department of Dermatology, Mount Sinai School of Medicine, New York, NY, USA.
Zhou
Xueyan
X
Weinstein
Elhav
E
Maryles
Billie
B
Zhang
Yanzhen
Y
Moore
Julian
J
Gao
Dayuan
D
Atencio
David P
DP
Rosenstein
Barry S
BS
Lebwohl
Mark
M
Chen
Hong-Duo
HD
Xiao
Ting
T
Wei
Huachen
H
D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity*; D002273:Carcinogens / Q000633:toxicity*; D005091:Exons; D005260:Female; D016158:Genes, p53; D051379:Mice; D008812:Mice, Hairless; D009154:Mutation; D009381:Neoplasms, Radiation-Induced / Q000235:genetics*; D012878:Skin Neoplasms / Q000139:chemically induced / Q000209:etiology / Q000235:genetics*; D014466:Ultraviolet Rays
D002273:Carcinogens; D001564:Benzo(a)pyrene