PT  - JOURNAL ARTICLE
AU  - Xin Yu
AU  - Adam R Blanden
AU  - Ashley Tsang
AU  - Saif Zaman
AU  - Yue Liu
AU  - John gilleran
AU  - Anthony F Bencivenga
AU  - S. David Kimball
AU  - Stewart N Loh
AU  - Darren R Carpizo
TI  - Thiosemicarbazones Functioning as Zinc Metallochaperones to Reactivate Mutant p53
AID  - 10.1124/mol.116.107409
DP  - 2017 Jan 01
TA  - Molecular Pharmacology
PG  - mol.116.107409
4099  - http://molpharm.aspetjournals.org/content/early/2017/03/20/mol.116.107409.short
4100  - http://molpharm.aspetjournals.org/content/early/2017/03/20/mol.116.107409.full
AB  - Small molecule restoration of wild type structure and function to mutant p53 (so - called mutant reactivation) is a highly sought after goal in cancer drug development. We previously discovered small molecule zinc chelators called zinc metallochaperones (ZMCs) reactivate mutant p53 by restoring zinc binding to zinc deficient p53 mutants. The lead compound identified from the NCI-60 human tumor cell lines screen, NSC319726 (ZMC1), belongs to the thiosemicarbazone (TSC) class of metal ion chelators that bind Fe, Cu, Mn, Zn, and other transition metals. Here, we investigate the other TSCs, NSC319725, NSC328784 identified in the same screen, as well as the more well studied TSC, 3-AP (Triapine), to determine if they function as ZMCs. We measured the zinc Kd, zinc ionophore activity, ability to restore zinc to purified p53 DNA binding domain (DBD), and ability to restore site-specific DNA binding to purified R175H-DBD in vitro. We tested all four TSCs in a number of cell based assays to examine mutant p53 reactivation and the generation of reactive oxygen species (ROS). We found that NSC319725 and NSC328784 behave similarly to ZMC1 in both biophysical and cell-based assays, and are heretofore named ZMC2 (NSC319725) and ZMC3 (NSC328784). 3-AP generates a ROS signal similar to ZMC1-3, but fails to function as a ZMC both in vitro and in cells and ultimately does not reactivate p53. These findings indicate that not all TSCs function as ZMCs, and much of their activity can be predicted by their affinity for zinc.