Abstract
p53 alterations in human tumors often involve missense mutations that may confer dominant-negative or gain-of-function properties. Dominant-negative effects result in inactivation of wild-type p53 protein in heterozygous mutant cells and as such in a p53 null phenotype. Gain-of-function effects can directly promote tumor development or metastasis through antiapoptotic mechanisms or transcriptional activation of (onco)genes. Here, we show, using conditional mouse technology, that epithelium-specific heterozygous expression of mutant p53 (i.e., the p53.R270H mutation that is equivalent to the human hotspot R273H) results in an increased incidence of spontaneous and UVB-induced skin tumors. Expression of p53.R270H exerted dominant-negative effects on latency, multiplicity, and progression status of UVB-induced but not spontaneous tumors. Surprisingly, gain-of-function properties of p53.R270H were not detected in skin epithelium. Apparently, dominant-negative and gain-of-function effects of mutant p53 are highly tissue specific and become most manifest upon stabilization of p53 after DNA damage.
Highlights
P53 is the most extensively studied tumor suppressor gene, encoding a transcriptional regulator that controls cell cycle progression and apoptosis [1]
To examine a potential dominantnegative and/or gain-of-function effect of the p53.R270H mutation on spontaneous tumorigenesis of epithelial cell origin, both female and male K14cre;p53+/+, K14cre;p53LSL-R270H/+, K14cre;p53F2-10/+, K14cre;p53F2-10/F2-10, and K14cre;p53LSL-R270H/F2-10 in a hairless background were followed as they aged for the development of spontaneous tumors
We have investigated potential dominantnegative and/or gain-of-function effects of a p53.R270H mutation, equivalent to the human hotspot R273H mutation, on development and progression of mouse skin tumors
Summary
P53 is the most extensively studied tumor suppressor gene, encoding a transcriptional regulator that controls cell cycle progression and apoptosis [1]. A second strain was engineered to carry an arginine to histidine mutation at p53 codon 270 [22], which corresponds to the p53.R273H hotspot mutation frequently found in human cancers and replaces an arginine that directly contacts DNA The phenotypes of these mutant mice indicate clear gain-of-function properties of mutant p53, with a metastatic tumor phenotype as the most striking difference between missense mutant mice and p53-null mice. Skin tumor development and acute cellular responses after UVB exposure were subsequently compared with those in conditional heterozygous and homozygous p53 knockout mice as controls. In this way, a clean skin-specific comparison of effects can be made between p53 missense and p53 null mutations. Especially after UVB-induced DNA damage, a p53.R270H mutation shows dominant-negative but not gain-of-function activities in skin tumor development
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