Arsenic Trioxide Rescues Structural p53 Mutations through a Cryptic Allosteric Site

Published: 20-11-2020| Version 1 | DOI: 10.17632/yy7hxp5td4.1
Contributors:
Shuo Chen,
Jia-Le Wu,
Ying Liang,
Yi-Gang Tang,
Hua-Xin Song,
Li-Li Wu,
Yang-Fei Xing,
Ni Yan,
Yun-Tong Li,
Zheng-Yuan Wang,
Shu-Jun Xiao,
Xin Lu,
Sai-Juan Chen,
Min Lu

Description

TP53 is the most frequently mutated gene in cancer, yet these mutations remain therapeutically non-actionable. Major challenges in drugging p53 mutations include heterogeneous mechanisms of inactivation and the absence of broadly-applicable allosteric sites. Here we report the identification of small molecules including arsenic trioxide (ATO), an established agent in treating acute promyelocytic leukemia, as cysteine-reactive compounds that rescue structural p53 mutations. Crystal structures of arsenic-bound p53 mutants reveal a cryptic allosteric site involving three arsenic coordinating cysteines within the DNA-binding domain, distal to the zinc-binding site. Arsenic binding stabilizes the DNA-binding loop-sheet-helix motif alongside the overall β-sandwich fold, endowing p53 mutants with thermostability and transcriptional activity. In cellular and mouse xenograft models, ATO reactivates mutant p53 for tumor suppression. Investigation of the most frequent twenty-five p53 mutations informs patient stratification for clinical exploration. Our results provide mechanistic basis for repurposing ATO to target p53 mutations for widely-applicable yet personalized cancer therapies.

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