Expression of a Mutant p53 Results in an Age-Related Demographic Shift in Spontaneous Lung Tumor Formation in Transgenic Mice

Background: Mutations in the P53 gene are among the most common genetic abnormalities in human lung cancer. Codon 273 in the sequence-specific DNA binding domain is one of the most frequently mutated sites. Methodology: To investigate the role of mutant p53 in lung tumorigenesis, a lung specific p53(273H) transgenic mouse model was developed. Rates of lung cancer formation in the transgenic animals and their littermates were evaluated by necropsy studies performed in progressive age cohorts ranging from 4 to 24 months. In order to establish the influence of other common genetic abnormalities in lung tumor formation in the animals, K-Ras gene mutation and p16INK4a (p16) promoter methylation were evaluated in a total of 281 transgenic mice and 189 non-transgenic littermates. Principal Findings: At the age extremes of 4–12 and 22–24 months no differences were observed, with very low prevalence of tumors in animals younger than 12 months, and a relatively high prevalence at age 22 months or older. However, the transgenic mice had a significant higher lung tumor rate than their non-transgenic counterparts during the age of 13–21 months, suggesting an age-related shift in lung tumor formation induced by the lung-specific expression of the huma