Cisplatin-Induced APE2 Overexpression Disrupts MYH9 Function and Causes Hearing Loss

Cisplatin remains a cornerstone chemotherapy for many solid tumors but is limited by dose-limiting toxicities, including nephrotoxicity, peripheral neuropathy, and ototoxicity—the latter of which disproportionately affects pediatric patients and lacks effective prevention strategies. Although therapeutic approaches to mitigate cisplatin-induced toxicity are urgently needed, the underlying mechanisms driving organ-specific injury remain incompletely understood. We previously identified apurinic/apyrimidinic endonuclease (APE) 2 as a critical mediator of cisplatin-induced acute kidney injury through disruption of mitochondrial integrity. In this study, we extend these findings to cisplatin-induced hearing loss (C-HL). We demonstrate that cisplatin selectively induces APE2, but not APE1, overexpression in murine and human outer hair cells. Using an inducible, outer hair cell–specific APE2 transgenic mouse model, we show that APE2 overexpression alone is sufficient to cause high-frequency hearing loss, accompanied by hair cell loss and stereocilia disorganization visualized by electron microscopy. Mechanistically, we identified a direct interaction between APE2 and MYH9, mapped the critical MYH9-binding domains, and demonstrated that APE2 knockdown preserved mitochondrial metabolism and protected cochlear cells from cisplatin-induced apoptosis. Notably, APE2 depletion activated an ATR–p53 signaling axis, promoting nuclear p53 localization and suppressing mitochondrial apoptotic pathways. Together, these findings reveal a noncanonical, APE2-dependent mechanism driving C-HL and suggest that targeting APE2 may offer a novel therapeutic strategy to prevent cisplatin-induced ototoxicity. Significance: These results reveal an unexpected role of APE2 via its interaction with MYH9, emphasizing the therapeutic promise of targeting APE2 for preventing C-HL in patients with cancer.