Restoration of wild-type conformation and activity of a temperature-sensitive mutant of p53 (p53(V272M)) by the cytoprotective aminothiol WR1065 in the esophageal cancer cell line TE-1.
ABSTRACT The aminothiol WR1065, the active metabolite of the cytoprotector amifostine, exerts its antimutagenic effects through free-radical scavenging and other unknown mechanisms. In an earlier report, we showed that WR1065 activates wild-type p53 in MCF-7 cells, leading to p53-dependent arrest in the G(1) phase of the cell cycle. To determine whether WR1065 activates p53 by modulating protein conformation, we analyzed its effects on p53 conformation and activity in the esophageal cancer cell line TE-1. This cell line contains a mutation in codon 272 of p53 (p53(V272M), with methionine instead of a valine), conferring temperature-sensitive properties to the p53 protein. At the nonpermissive temperature (37 degrees C), p53(V272M) adopts the mutant p53 conformation (nonreactive with the antibody PAb1620), does not bind specifically to DNA, and is not activated in response to DNA-damaging treatment. However, treatment with 0.5-4 mM WR1065 partially restored wild-type conformation at 37 degrees C, stimulated DNA binding activity, and increased the expression of p53 target genes WAF-1, GADD45, and MDM2, leading to cell-cycle arrest in G(1). These results suggest that WR1065 activates p53 through a mechanism distinct from DNA-damage signaling, which involves modulation of p53 protein conformation.
- SourceAvailable from: Alexei Vazquez
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- "The reactivation of p53 in mouse tumor models has been shown to be a highly effective therapeutic strategy (Martins et al., 2006; Ventura et al., 2007; Xue et al., 2007). Several small molecules have been claimed to reactivate mutant p53, including CP-31398, WR-1065, PRIMA-1 and MIRA-1 (Bykov et al., 2002; Bykov et al., 2005; Foster et al., 1999; North et al., 2002). With the exception of one compound, WR1065, all have been identified using traditional chemical screens (Bykov et al., 2002; Bykov et al., 2005). "
ABSTRACT: Rescuing the function of mutant p53 protein is an attractive cancer therapeutic strategy. Using the National Cancer Institute's anticancer drug screen data, we identified two compounds from the thiosemicarbazone family that manifest increased growth inhibitory activity in mutant p53 cells, particularly for the p53(R175) mutant. Mechanistic studies reveal that NSC319726 restores WT structure and function to the p53(R175) mutant. This compound kills p53(R172H) knockin mice with extensive apoptosis and inhibits xenograft tumor growth in a 175-allele-specific mutant p53-dependent manner. This activity depends upon the zinc ion chelating properties of the compound as well as redox changes. These data identify NSC319726 as a p53(R175) mutant reactivator and as a lead compound for p53-targeted drug development.Cancer cell 05/2012; 21(5):614-25. DOI:10.1016/j.ccr.2012.03.042 · 23.89 Impact Factor
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- "In fact, the structure of wild-type p53 itself naturally comprises unfolded regions and displays high tendency to aggregation (Sakaguchi et al., 1998; Bell et al., 2002; Veprintsev et al., 2006). The prototype of these reactivating agents are CP-31398 (Foster et al., 1999) ellipticine (Shi et al., 1998), (North et al., 2002), MIRA-1 (Bykov et al., 2005), RITA (Grinkevich et al., 2009), and PRIMA-1 (Lambert et al., 2009). A third category of reactivating molecules is represented by short peptides encompassing the C-terminal region of p53 that, when introduced into tumor cells harboring p53 mutants, lead to induction of p53-regulated genes and apoptosis (Selivanova et al., 1997). "
ABSTRACT: Tumor-derived mutant forms of p53 compromise its DNA binding, transcriptional, and growth regulatory activity in a manner that is dependent upon the cell-type and the type of mutation. Given the high frequency of p53 mutations in human tumors, reactivation of the p53 pathway has been widely proposed as beneficial for cancer therapy. In support of this possibility p53 mutants possess a certain degree of conformational flexibility that allows for re-induction of function by a number of structurally different artificial compounds or by short peptides. This raises the question of whether physiological pathways for p53 mutant reactivation also exist and can be exploited therapeutically. The activity of wild-type p53 is modulated by various acetyl-transferases and deacetylases, but whether acetylation influences signaling by p53 mutant is still unknown. Here, we show that the PCAF acetyl-transferase is down-regulated in tumors harboring p53 mutants, where its re-expression leads to p53 acetylation and to cell death. Furthermore, acetylation restores the DNA-binding ability of p53 mutants in vitro and expression of PCAF, or treatment with deacetylase inhibitors, promotes their binding to p53-regulated promoters and transcriptional activity in vivo. These data suggest that PCAF-mediated acetylation rescues activity of at least a set of p53 mutations. Therefore, we propose that dis-regulation of PCAF activity is a pre-requisite for p53 mutant loss of function and for the oncogenic potential acquired by neoplastic cells expressing these proteins. Our findings offer a new rationale for therapeutic targeting of PCAF activity in tumors harboring oncogenic versions of p53.Journal of Cellular Physiology 11/2010; 225(2):394-405. DOI:10.1002/jcp.22285 · 3.87 Impact Factor
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- "The peptide was shown to stabilize wild-type and mutant p53 in vitro (Friedler et al., 2002) and elevated the activity of mutant p53 in cancer cell lines (Issaeva et al., 2003). There have been numerous reports of other molecules that restore mutant p53 activity in cells (Bykov et al., 2002; Bykov et al., 2005; Foster et al., 1999; North et al., 2002). However, how these molecules reactivate p53 or, in the case of those that are known not to bind wild-type or mutant p53 (i.e., CP-31398), induce p53-like effects remains uncertain. "
ABSTRACT: The p53 cancer mutation Y220C induces formation of a cavity on the protein's surface that can accommodate stabilizing small molecules. We combined fragment screening and molecular dynamics to assess the druggability of p53-Y220C and map ligand interaction sites within the mutational cavity. Elucidation of the binding mode of fragment hits by crystallography yielded a clear picture of how a drug might dock in the cavity. Simulations that solvate the protein with isopropanol found additional sites that extend the druggable surface. Moreover, structural observations and simulation revealed the dynamic landscape of the cavity, which improves our understanding of the impact of the mutation on p53 stability. This underpins the importance of considering flexibility of the cavity in screening for optimized ligands. Our findings provide a blueprint for the design of effective drugs that rescue p53-Y220C.Chemistry & biology 01/2010; 17(1):46-56. DOI:10.1016/j.chembiol.2009.12.011 · 6.59 Impact Factor