Small molecule restoration of wildtype structure and function of mutant p53 using a novel zinc-metallochaperone based mechanism

// Xin Yu 1,2,* , Adam R. Blanden 3,* , Sumana Narayanan 2 , Lalithapriya Jayakumar 2 , David Lubin 3 , David Augeri 4 , S. David Kimball 4 , Stewart N. Loh 3 and Darren R. Carpizo 1,2 1 Rutgers Cancer Institute of New Jersey, New Jersey 2 Department of Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey 3 Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 4 Department of Medicinal Chemistry, Rutgers Ernest Mario School of Pharmacy, Piscataway, New Jersey * These authors contributed equally to this work Correspondence: Stewart N. Loh, email: // Darren R. Carpizo, email: // Keywords : mutant p53 reactivation, zinc-metallochaperone, mutant p53 targeted drug, thiosemicarbazone, reactive oxygen species (ROS) Received : July 29, 2014 Accepted : September 02, 2014 Published : September 03, 2014 Abstract NSC319726 (ZMC1) is a small molecule that reactivates mutant p53 by restoration of WT structure/function to the most common p53 missense mutant (p53-R175H). We investigated the mechanism by which ZMC1 reactivates p53-R175H and provide evidence that ZMC1: 1) restores WT structure by functioning as a zinc-metallochaperone, providing an optimal concentration of zinc to facilitate proper folding; and 2) increases cellular reactive oxygen species that transactivate the newly conformed p53-R175H (via post-translational modifications), inducing an apoptotic program. We not only demonstrate that this zinc metallochaperone function is possessed by other zinc-binding small molecules, but that it can reactivate other p53 mutants with impaired zinc binding. This represents a novel mechanism for an anti-cancer drug and a new pathway to drug mutant p53. Significance: We have elucidated a novel mechanism to restore wild-type structure/function to mutant p53 using small molecules functioning as zinc-metallochaperones. The pharmacologic delivery of a metal ion to restore proper folding of a mutant protein is unique to medicinal chemistry and represents a new pathway to drug mutant p53.