Article

Mutant p53: One name, many proteins

Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Genes & development (Impact Factor: 10.8). 06/2012; 26(12):1268-86. DOI: 10.1101/gad.190678.112
Source: PubMed

ABSTRACT

There is now strong evidence that mutation not only abrogates p53 tumor-suppressive functions, but in some instances can also endow mutant proteins with novel activities. Such neomorphic p53 proteins are capable of dramatically altering tumor cell behavior, primarily through their interactions with other cellular proteins and regulation of cancer cell transcriptional programs. Different missense mutations in p53 may confer unique activities and thereby offer insight into the mutagenic events that drive tumor progression. Here we review mechanisms by which mutant p53 exerts its cellular effects, with a particular focus on the burgeoning mutant p53 transcriptome, and discuss the biological and clinical consequences of mutant p53 gain of function.

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    • "This inhibitory effect was further enhanced to 326 about 84 % at 1 µM of Lebein. As p53 is the most common tumor suppressor and most 327 commonly mutated and functionally inactivated gene in 50 % of all human cancers[36], we 328 checked whether Lebein effect on LS174 colon cancer cells that retains functional p53, could 329 be extrapolated to other colon cancer cell lines. Thus, we assessed the effect of Lebein on the 330 growth of two additional colorectal cancer cell lines, HCT116 which contains also the wild 331 type p53 gene and HT29 cell line which is a p53 mutant cell line. "
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    ABSTRACT: Lebein, is an heterodimeric disintegrin isolated from Macrovipera lebetina snake venom that was previously characterized as an inhibitor of ADP-induced platelet aggregation. In this study, we investigated the effect of Lebein on the p53-dependent growth of human colon adenocarcinoma cell lines. We found that Lebein significantly inhibited LS174 (p53wt), HCT116 (p53wt), and HT29 (p53mut) colon cancer cell viability by inducing cell cycle arrest through the modulation of expression levels of the tumor suppression factor p53, cell cycle regulating proteins cyclin D1, CDK2, CDK4, retinoblastoma (Rb), CDK1, and cyclin-dependent kinase inhibitors p21 and p27. Interestingly, Lebein-induced apoptosis of colon cancer cells was dependent on their p53 status. Thus, in LS174 cells, cell death was associated with PARP cleavage and the activation of caspases 3 and 8 while in HCT116 cells, Lebein induced caspase-independent apoptosis through increased expression of apoptosis inducing factor (AIF). In LS174 cells, Lebein triggers the activation of the MAPK ERK1/2 pathway through induction of reactive oxygen species (ROS). It also decreased cell adhesion and migration to fibronectin through down regulation of α5β1 integrin. Moreover, Lebein significantly reduced the expression of two angiogenesis stimulators, Vascular Endothelial Growth Factor (VEGF) and Neuropilin 1 (NRP1). It inhibited the VEGF-induced neovascularization process in the quail embryonic CAM system and blocked the development of human colon adenocarcinoma in nude mice. Overall, our work indicates that Lebein may be useful to design a new therapy against colon cancer. © 2016 Wiley Periodicals, Inc.
    Full-text · Article · Jan 2016 · Molecular Carcinogenesis
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    • "However, this approach is not straightforward [24]. Because p53 mutants acquire their own specific functions and alter tumor functions, disrupting mutant p53 is an alternative attractive approach [6] [10]. Recent studies have shown in breast cancer and colon cancer cells in culture that disrupting p53 expression using siRNA leads to catastrophic events and cell death in cells expressing mutant p53 without affecting cell viability in cells with WT p53 [25] [26]. "
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    ABSTRACT: Evolutionary Action analyses of The Cancer Gene Atlas data sets show that many specific p53 missense and gain-of-function mutations are selectively overrepresented and functional in high-grade serous ovarian cancer (HGSC). As homozygous alleles, p53 mutants are differentially associated with specific loss of heterozygosity (R273; chromosome 17); copy number variation (R175H; chromosome 9); and up-stream, cancer-related regulatory pathways. The expression of immune-related cytokines was selectively related to p53 status, showing for the first time that specific p53 mutants impact, and are related to, the immune subtype of ovarian cancer. Although the majority (31%) of HGSCs exhibit loss of heterozygosity, a significant number (24%) maintain a wild-type (WT) allele and represent another HGSC subtype that is not well defined. Using human and mouse cell lines, we show that specific p53 mutants differentially alter endogenous WT p53 activity; target gene expression; and responses to nutlin-3a, a small molecular that activates WT p53 leading to apoptosis, providing “proof of principle” that ovarian cancer cells expressing WT and mutant alleles represent a distinct ovarian cancer subtype. We also show that siRNA knock down of endogenous p53 in cells expressing homozygous mutant alleles causes apoptosis, whereas cells expressing WT p53 (or are heterozygous for WT and mutant p53 alleles) are highly resistant. Therefore, despite different gene regulatory pathways associated with specific p53 mutants, silencing mutant p53 might be a suitable, powerful, global strategy for blocking ovarian cancer growth in those tumors that rely on mutant p53 functions for survival. Knowing p53 mutational status in HGSC should permit new strategies tailored to control this disease.
    Full-text · Article · Oct 2015 · Neoplasia (New York, N.Y.)
    • "In Li-Fraumeni patients, missense mutation was reported to lead to earlier tumor onset than other forms of p53 loss (Bougeard et al. 2008). p53 hot spot mutant proteins have been reported to associate with chromatin and alter a cell's transcriptional profile, leading to oncogenic cellular changes (Di Agostino et al. 2006; Stambolsky et al. 2010; Do et al. 2012; Freed-Pastor et al. 2012; Cooks et al. 2013). Although a common view is that p53 hot spot mutants acquire neomorphic properties , many activities of mutant p53 are likely conserved from wild-type p53 and generate different cellular outcomes due to differences in their distribution within cellular chromatin. "
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    ABSTRACT: Mutant p53 impacts the expression of numerous genes at the level of transcription to mediate oncogenesis. We identified vascular endothelial growth factor receptor 2 (VEGFR2), the primary functional VEGF receptor that mediates endothelial cell vascularization, as a mutant p53 transcriptional target in multiple breast cancer cell lines. Up-regulation of VEGFR2 mediates the role of mutant p53 in increasing cellular growth in two-dimensional (2D) and three-dimensional (3D) culture conditions. Mutant p53 binds near the VEGFR2 promoter transcriptional start site and plays a role in maintaining an open conformation at that location. Relatedly, mutant p53 interacts with the SWI/SNF complex, which is required for remodeling the VEGFR2 promoter. By both querying individual genes regulated by mutant p53 and performing RNA sequencing, the results indicate that >40% of all mutant p53-regulated gene expression is mediated by SWI/SNF. We surmise that mutant p53 impacts transcription of VEGFR2 as well as myriad other genes by promoter remodeling through interaction with and likely regulation of the SWI/SNF chromatin remodeling complex. Therefore, not only might mutant p53-expressing tumors be susceptible to anti VEGF therapies, impacting SWI/SNF tumor suppressor function in mutant p53 tumors may also have therapeutic potential. © 2015 Pfister et al.; Published by Cold Spring Harbor Laboratory Press.
    No preview · Article · Jun 2015 · Genes & development
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