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Effect of heterozygous loss of p53 on benzo[a]pyrene‐induced mutations and tumors in DNA repair‐deficient XPA mice
Author(s) -
van Oostrom Conny Th. M.,
Boeve Miranda,
van den Berg Jolanda,
de Vries Annemieke,
Dollé Martijn E.T.,
Beems Rudolf B.,
van Kreijl Coen F.,
Vijg Jan,
van Steeg Harry
Publication year - 1999
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/(sici)1098-2280(1999)34:2/3<124::aid-em11>3.0.co;2-f
Subject(s) - biology , mutation , microbiology and biotechnology , mutation frequency , nucleotide excision repair , genetically modified mouse , carcinogen , cancer research , dna repair , tumor suppressor gene , carcinogenesis , benzo(a)pyrene , spleen , gene mutation , transgene , gene , genetics , immunology
XPA ‐deficient mice have a complete deficiency in nucleotide excision repair, and as such they display a cancer predisposition after exposure to several carcinogens. Besides being sensitive to genotoxic agents applied to the skin, they are also susceptible to human carcinogens given orally, like benzo[a]pyrene (B[a]P). To study the role of the tumor suppressor gene p 53 in DNA repair, gene mutation, and tumor induction, we crossed XPA ‐deficient mice with p 53 knockout mice and lacZ (pUR288) gene marker mice. When treated orally (by gavage) with B[a]P, the XPA −/− / p 53 +/− double transgenic mice developed tumors much earlier and with higher frequency compared to their single transgenic counterparts. The major tumor type found in all genotypes was generalized lymphoma mainly residing in the spleen; several sarcomas were observed in p 53 +/− and XPA −/− / p 53 +/− mice. Next, we determined lacZ mutation frequencies in several (non)target tissues. It appeared that in the spleen (the major tumor target tissue) of XPA −/− and XPA −/− / p 53 +/− mice the lacZ mutation frequency was significantly elevated (80–100 × 10 −5 ), and was two times higher as found in spleens of B[a]P‐treated WT and p 53 +/− mice ( P = 0.003). In nontumor target tissues like liver and lung, we found a moderate increase in the lacZ gene mutation frequency (30–40 × 10 −5 ), which was independent of the genotype. The results obtained with the DNA‐repair deficient XPA mice indicate that a significantly increased lacZ mutation frequency in a particular organ/tissue is an early marker for tumor development at later stages at the same site. However, the synergistic effect of a XPA −/− ‐ and a p 53 +/− ‐deficiency in tumor development is not reflected by an absolute increase in the lacZ mutation frequency in the major tumor target tissue of XPA −/− / p 53 +/− or p 53 +/− mice compared to that of XPA −/− and WT mice, respectively. Environ. Mol. Mutagen. 34:124–130, 1999 © 1999 Wiley‐Liss, Inc.