In Vivo Activation of the p53 Tumor Suppressor Pathway by an Engineered Cyclotide

Journal of the American Chemical Society (Impact Factor: 11.44). 07/2013; 135(31). DOI: 10.1021/ja405108p
Source: PubMed

ABSTRACT The overexpression of Hdm2 and HdmX is a common mechanism used by many tumor cells to inactive the p53 tumor suppressor pathway promoting cell survival. Targeting Hdm2 and HdmX has emerged as a validated therapeutic strategy for treating cancers with wild-type p53. Small linear peptides mimicking the N-terminal fragment of p53 have been shown to be potent Hdm2/HdmX antagonists. The potential therapeutic use of these peptides, however, is limited by their poor stability and bioavailability. Here, we report the engineering of the cyclotide MCoTI-I to efficiently antagonize intracellular p53 degradation. The resulting cyclotide MCo-PMI was able to bind with low nanomolar affinity to both Hdm2 and HdmX, showed high stability in human serum and was cytotoxic to wild-type p53 cancer cell lines by activating the p53 tumor suppressor pathway both in vitro and in vivo. These features make the cyclotide MCoTI-I an optimal scaffold for targeting intracellular protein-protein interactions.

Download full-text


Available from: Yanbin Ji, Oct 16, 2014
1 Follower
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cellular tumor antigen p53 is crucial for cancer prevention via different mechanisms. E3 ubiquitin-protein ligase HDM2 binds to p53, blocks its ability to activate transcription, and therefore acts as a negative regulator. Blocking p53 binding site on HDM2 was believed to generate efficient antitumor agents. So far, limited scaffolds were reported with HDM2 antagonist activity. Herein, diphenylpyrroles were introduced and evaluated as a novel scaffold in the field of p53 activators. An efficient synthesis of novel 3-heteroaryl-pyrroles is described via reactions of E-3-(dimethylamino)-1-(2-methyl-4,5-diphenyl-1H-pyrrol-3-yl)prop-2-en-1-one or E-1-(2-methyl-4,5-diphenyl-1H-pyrrol-3-yl)-3-morpholinoprop-2-en-1-one with hydrazine hydrate, phenyl hydrazine, hydroxylamine, various heterocyclic amines and active methylene compounds.
    European Journal of Medicinal Chemistry 06/2014; 82C:472-479. DOI:10.1016/j.ejmech.2014.05.082 · 3.43 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An efficient synthesis of novel 4,5-diphenyl-3-heteroaryl-pyrroles were synthesized and evaluated as a novel scaffold in the field of p53 activators.
  • [Show abstract] [Hide abstract]
    ABSTRACT: MCoTI-II is a head-to-tail cyclic peptide with potent trypsin inhibitory activity and on the basis of its exceptional proteolytic stability is a valuable template for the design of novel drug leads. Insights into inhibitor dynamics and interactions with biological targets are critical for drug design studies, particularly for protease targets. Here we show that the cyclization and active site loops of MCoTI-II are flexible in solution, but when bound to trypsin the active site loop converges to a single well-defined conformation. This finding of reduced flexibility on binding is in contrast to a recent study on the homologous peptide MCoTI-I, which suggested that regions of the peptide are more flexible upon binding to trypsin. We provide a possible explanation for this discrepancy based on degradation of the complex over time. Our study also unexpectedly shows that the cyclization loop, not present in acyclic homologues, facilitates potent trypsin inhibitory activity by engaging in direct binding interactions with trypsin.
    Journal of Biological Chemistry 10/2013; 288(50). DOI:10.1074/jbc.M113.528240 · 4.60 Impact Factor