Targeted rescue of a destabilized mutant of p53 by an in silico screened drug

Abstract

The tumor suppressor p53 is mutationally inactivated in Ϸ50% of human cancers. Approximately one-third of the mutations lower the melting temperature of the protein, leading to its rapid denaturation. Small molecules that bind to those mutants and stabilize them could be effective anticancer drugs. The mutation Y220C, which occurs in Ϸ75,000 new cancer cases per annum, creates a surface cavity that destabilizes the protein by 4 kcal/mol, at a site that is not functional. We have designed a series of binding molecules from an in silico analysis of the crystal structure using virtual screening and rational drug design. One of them, a carbazole derivative (PhiKan083), binds to the cavity with a dissociation constant of Ϸ150 M. It raises the melting temperature of the mutant and slows down its rate of denaturation. We have solved the crystal structure of the proteinPhiKan083 complex at 1.5-Å resolution. The structure implicates key interactions between the protein and ligand and conformational changes that occur on binding, which will provide a basis for lead optimization. The Y220C mutant is an excellent ''druggable'' target for developing and testing novel anticancer drugs based on protein stabilization. We point out some general principles in relationships between binding constants, raising of melting temperatures, and increase of protein half-lives by stabilizing ligands.NMR screen ͉ oncogenic mutant ͉ protein stabilization ͉ virtual drug design ͉ crystal structure

Does Notch play a tumor suppressor role across diverse squamous cell carcinomas?

“…Notably, structure‐guided analysis of the functional consequences of NOTCH cancer mutations, as we present in this review, may provide new clues and advance the development of drugs that can restore aberrant Notch signaling. This strategy was proved to be applicable for another tumor suppressor, p5398, 99, and therefore may represent an attractive future direction of targeted therapy of SCC. Emerging new understanding of the Notch pathway in diverse SCC types will likely enhance the possibility for improvement in therapy of SCC.…”

Major apoptotic mechanisms and genes involved in apoptosis

“…There is an increasing attention to develop different strategies that can modulate p53-dependent apoptotic pathways such as inhibition of p53-MDM2 interaction using MDM2 inhibitors, restoring mutated p53 back to its wild-type form and p53 vaccines [158][159][160].…”

Molecular Mechanisms of Apoptosis and Roles in Cancer Development and Treatment

“…PK083 (the carbazole derivative) interacts with a small cleft in the destabilized p53 mutant and raises the melting temperature of Y220C mutant p53 and restores its function (Boeckler et al, 2008).…”