RT Journal Article
SR Electronic
T1 Thiosemicarbazones Functioning as Zinc Metallochaperones to Reactivate Mutant p53
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 567
OP 575
DO 10.1124/mol.116.107409
VO 91
IS 6
A1 Xin Yu
A1 Adam Blanden
A1 Ashley T. Tsang
A1 Saif Zaman
A1 Yue Liu
A1 John Gilleran
A1 Anthony F. Bencivenga
A1 S. David Kimball
A1 Stewart N. Loh
A1 Darren R. Carpizo
YR 2017
UL http://molpharm.aspetjournals.org/content/91/6/567.abstract
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 that 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 iron, copper, magnesium, zinc, and other transition metals. Here, we have investigated the other TSCs, NSC319725 and NSC328784, identified in the same screen, as well as the more well studied TSC, 3-AP (Triapine), to determine whether 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 it 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.