Differential effects of p53 mutants on the growth of human bronchial epithelial cells

We investigated the effects of five different p53 mutants on the growth of primary cultures of normal human bronchial epithelial (NHBE) cells. The five defective viral pZIP-Neo constructs contained the following mutations at mutational hot-spots found in human cancers: codons 143ala, 175his, 248trp, 249ser, and 273his. NHBE cells were infected with the p53 mutants, wild-type p53, or the pZIP-Neo vector control. The 143ala, 248trp, and 273his mutants, as well as wild-type p53, decreased the colony-forming efficiency and inhibited the growth of NHBE cells. The 175his mutant did not significantly change the growth rates. In NHBE cells from three donors, the 249ser mutant conferred a substantial growth advantage to the NHBE cells in a colony-forming-efficiency assay. In NHBE cells isolated from one donor, the 249ser mutant also produced a significant life span extension. These cells grew rapidly through 80 population doublings and entered an apparent "crisis" in passage 14. Karyotypic analyses of one culture at multiple passages revealed aneuploid populations with alterations of chromosomes 5, 11, and 13; quantitative DNA analysis detected aneuploidy in late passages from that culture and two other primary cultures. These data demonstrated that the codon 249ser mutation could provide a growth advantage to bronchial epithelial cells and suggest that this mutant protein can induce genomic instability.