Reactivation of the p53 Tumor Suppressor Pathway by a Stapled p53 Peptide

Abstract

Transcription factor p53 induces cell cycle arrest and apoptosis in response to DNA damage 1 and cellular stress, 2 thereby playing a critical role in protecting cells from malignant transformation. The E3 ubiquitin ligase hDM2 controls p53 levels through a direct binding interaction that neutralizes p53 transactivation activity, exports nuclear p53, and targets it for degradation via the ubiquitylation-proteasomal pathway. 3,4 Loss of p53 activity, either by deletion, mutation, or hDM2 overexpression, is the most common defect in human cancer. 5 Tumors with preserved expression of wild type p53 are rendered vulnerable by pharmacologic approaches that stabilize native p53. In this context, hDM2 targeting has emerged as a validated approach to restore p53 activity and resensitize cancer cells to apoptosis in vitro and in vivo. 6 Supporting Information Available: Complete ref 16h, peptide characterization, experimentals, and supplementary figures. This material is available free of charge via the Internet at http://pubs.acs.org.

Altered nucleophosmin transport in acute myeloid leukaemia with mutated NPM1: molecular basis and clinical implications

“…122 A p53-derived stapled peptide disrupted p53-HDM2 interaction, activating a p53-dependent transcriptional response and triggering apoptosis in HDM2 overexpressing cells. 123 Finally, it could be feasible to screen a library of pharmacological agents on the OCI-AML3 cell line 68 or primary NPMc þ AML cells from patients, in a search for drug sensitivity that is specifically associated with the NPM1 mutation. Schlenk et al 113 retrospectively analysed the prognostic impact of NPM1, CEBPA, FLT3 and MLL gene mutations on the effects of ATRA treatment in AML patients 460 years old (excluding APL) who were enrolled in the HD98B randomized trial.…”

MDM2 and MDM4: p53 regulators as targets in anticancer therapy

“…Different strategies were then designed to stabilize the helical structure of these peptides in solution. For example, hydrocarbon stapling recently led to the design of a promising peptide, though its efficacy remains to be tested in vivo (Bernal et al, 2007). A similar approach has consisted in the screening for chemical molecules that mimic p53 BoxI peptides to disrupt p53-MDM2 interactions.…”

Protein grafting of p53TAD onto a leucine zipper scaffold generates a potent HDM dual inhibitor

“…Our rational grafting approach has successfully elicited the molecular mimicry of the N-terminal domain of p53 (p53TAD) in the grafted p53LZ2, enforcing the disruption of p53-HDM2 and/or HDMX interaction in vitro and in vivo. The wild-type p53TAD exists with B11% a-helices in solution with the majority as random coil 25 . Several pioneering concepts suggested that conformation-stabilized polypeptides that capture their bioactive forms have benefits in vitro and in vivo [42][43][44][45] .…”

“…In fact, the p53TAD is largely unstructured under physiological conditions, while transforming into an a-helical conformation when interacting with target proteins in the presence of binding partners such as RPA and HDMs 24 . Recent studies of a stapled p53-based peptide, which contains a chemical hydrocarbon crosslink within a synthetic peptide (stapling), demonstrated that the p53 peptidomimetic restored the intrinsic a-helix-forming tendency of p53TAD and conferred the intracellular protease resistance [25][26][27] . Such seminal structural insights into the stabilized a-helix (SAH) of p53 inspired us to challenge this attractive target in oncology and design a new molecular entity of a p53TAD mimetic.…”