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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.

Group of Molecular Carcinogenesis, International Agency for Research on Cancer, Lyon, France.
Molecular Carcinogenesis (Impact Factor: 4.77). 04/2002; 33(3):181-8.
Source: PubMed

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.

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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). "
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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). "
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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. "
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