Aldehyde dehydrogenase 9A1 promotes cisplatin resistance in laryngeal squamous cell carcinoma by enhancing PTEN-induced kinase 1-Parkin-mediated mitophagy.

Cisplatin resistance remains a major challenge in laryngeal squamous cell carcinoma (LSCC) treatment. Aldehyde dehydrogenase 9A1 (ALDH9A1), a mitochondrial matrix protein, is dysregulated in various cancers, but its role in LSCC is unclear. This study demonstrates that ALDH9A1 is significantly downregulated in LSCC tissues, and low ALDH9A1 expression correlates with poor patient prognosis. Functionally, ALDH9A1 overexpression inhibits LSCC cell proliferation, migration, and invasion while promoting apoptosis. Mechanistically, ALDH9A1 interacts with and stabilizes PTEN-induced kinase 1 (PINK1), leading to activation of PINK1-Parkin-mediated mitophagy. Under cisplatin treatment, ALDH9A1 is upregulated and induces protective mitophagy, contributing to cisplatin resistance. Inhibition of mitophagy with chloroquine sensitizes LSCC cells to cisplatin. These findings identify ALDH9A1 as a key regulator of mitophagy and cisplatin resistance in LSCC, suggesting that targeting the ALDH9A1/PINK1 axis could provide a novel therapeutic strategy for overcoming cisplatin resistance.