title: Mice with alterations in both p53 and Ink4a/Arf display a striking increase in lung tumor multiplicity and progression: differential chemopreventive effect of budesonide in wild-type and mutant A/J mice.
abstract: p53 transgenic mice carrying a dominant negative mutation were crossed with Ink4A/Arf heterozygous-deficient mice to investigate whether there is a synergy between these two germ-line mutations in promoting carcinogen-induced lung tumor progression in mice. Mice with a p53 dominant negative mutation and Ink4A/Arf heterozygous deficiency exhibited >20-fold increase in tumor volume compared with approximately 4-fold increase in Ink4A/Arf heterozygous-deficient mice and a 9-fold increase in mice with only the p53 dominant negative mutation. The effect of Ink4A/Arf heterozygous deficiency on lung tumor progression occurred late in the carcinogenesis process (>30 weeks after carcinogen treatment). In addition, most of the lung tumors (approximately 80%) from mice with a p53 mutation and deletion of Ink4A/Arf were lung adenocarcinomas. In contrast, lung adenocarcinomas were seen in <10% of the lung tumors from the wild-type mice and approximately 50% of the lung tumors from Ink4a/Arf heterozygous-deficient or p53 mutant mice. These results indicate a significant synergistic interaction between the presence of a mutant p53 transgene and the Ink4A/Arf deletion during lung tumor progression (P < 0.01). The usefulness of this new mouse model in lung cancer chemoprevention was examined. The chemopreventive efficacy of budesonide was examined in wild-type mice, mice with Ink4A/Arf heterozygous deficiency, mice with a mutation in the p53 gene, or mice with both a mutation in the p53 gene and deletion in the Ink4A/Arf locus. Mice treated with budesonide displayed an average of 90% inhibition of lung tumor progression in a standard 18-week chemoprevention assay, regardless of p53 and/or Ink4A/Arf status. However, the efficacy of budesonide against lung tumor progression decreased from 94 to 77% (P = 0.07) in mice with alterations in both p53 and Ink4A/Arf in a 40-week chemoprevention assay. Similarly, when mice bearing established lung adenomas were treated with budesonide, genotype-dependent differential effects of budesonide in wild-type and mutant mice were clearly revealed with a 82, 64, 45, and 33% decrease in tumor volume in wild-type mice, p53(+/+)Ink4a/Arf(+/-) mice, p53(+/-)Ink4a/Arf(+/+) mice, and p53(+/-)Ink4a/Arf(+/-), respectively. Thus, mutant mice with alterations in p53 and/or Ink4A/Arf exhibited a significant resistance to chemoprevention by budesonide. Because p53 and Ink4a/Arf mutations are the most prevalent mutations in human lung cancers, the effectiveness of chemopreventive agents on the mutant A/J mice containing alterations with p53 and Ink4a/Arf is the best preclinical estimate of their efficacy in humans. Thus, the mutant A/J mouse model should prove useful for chemoprevention studies.
authors.affiliation: Department of Surgery, The Alvin J. Siteman Cancer Center, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
authors.forename: Yian
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhongqiu
authors.initials: Z
authors.lastname: Zhang
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kastens
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Lubet
authors.forename: Ming
authors.initials: M
authors.lastname: You
mesh_terms: D000230:Adenocarcinoma / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control*; D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D001564:Benzo(a)pyrene; D019819:Budesonide / Q000494:pharmacology*; D002273:Carcinogens; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000172:deficiency / Q000235:genetics*; D018450:Disease Progression; D005260:Female; D016158:Genes, p53 / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D018095:Germ-Line Mutation; D007178:Inbreeding; D008175:Lung Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008822:Mice, Transgenic
chemical_list: D016588:Anticarcinogenic Agents; D002273:Carcinogens; D019941:Cyclin-Dependent Kinase Inhibitor p16; D001564:Benzo(a)pyrene; D019819:Budesonide