The deubiquitinase inhibitor WP1130 drives nuclear aggregation and reactivation of mutant p53 for selective cancer cell targeting

Abstract

Mutations in the TP53 gene may lead to the loss of its tumor suppressor function and the acquisition of oncogenic properties. The enhanced stability of mutant p53 (mutp53) is one of the pivotal factors for its oncogenic functions, rendering proteins implicated in mutp53 stabilization as promising targets for therapeutic intervention. Although deubiquitinases (DUBs) are commonly deregulated in various cancers, their specific impact on mutp53 stabilization remains largely unexplored. In this study, we demonstrated the involvement of DUBs—USP5 and USP9X in—enhancing mutp53 stability while revealing the effects of DUB inhibitor WP1130 in selectively destabilizing different p53 mutants in cancer cells of various origins. Mechanistically, WP1130 induced mutp53 ubiquitination and nuclear aggregation, resulting in its partitioning to the detergent-insoluble fraction. Moreover, combined treatment with the proteasome inhibitor augmented mutp53 accumulation in this fraction, indicating proteasomal degradation of these aggregates. Interestingly, WP1130 did not alter the stability or induce aggregation of WTp53 protein, suggesting its selective targeting of mutp53. Furthermore, WP1130 disrupted the interaction of mutp53 with HSP40 and HSP90 while promoting its association with ubiquitin ligase CHIP, thereby facilitating mutp53 destabilization. Notably, WP1130 reactivated mutp53 via induction of a wild-type-like p53 conformation, upregulating its downstream effectors and inducing apoptosis, possibly due to its targeted binding near the mutation site, as suggested by our in silico analysis. These findings highlight the roles of USP9X and USP5 in mutp53 stabilization and underscore the therapeutic potential of DUB inhibitor WP1130 for the selective targeting of mutp53-expressing cancer cells.