Objective To investigate the role of spermidine/spermine N1-acetyltransferase 1 (SAT1) in cisplatin-induced endoplasmic reticulum stress in mouse-derived immortalized auditory hair cell-like HEI-OC1 cells, and to define the impact of SAT1 on cisplatin-induced damage to cochlear hair cells.Methods HEI-OC1 cells were divided into four groups: siRNA negative control group (siNC), SAT1 gene silencing group (siSAT1), negative control with cisplatin treatment group (siNC + DDP), and SAT1 gene silencing with cisplatin treatment group (siSAT1 + DDP). The cells were transfected with SAT1-targeting siRNA and subsequently treated with cisplatin. Cell proliferation from 0 to 72 h was assessed using the CCK-8 assay; apoptosis and ultrastructural changes were analyzed by flow cytometry and transmission electron microscopy; endoplasmic reticulum stress markers (IRE1α, XBP1s, GRP78, ATF6) and apoptotic protein Caspase-12 were detected by Western blotting.Results All four SAT1-siRNA treatments effectively silenced SAT1 gene expression 24 hours post-transfection, with the most pronounced reduction observed in the siSAT1-740 group (P < 0.05). Consequently, the siSAT1-740 group was selected for subsequent experiments. Western blotting results showed that the protein expression level of SAT1 in the siNC group was significantly higher than that in the siSAT1 group (P < 0.05). Flow cytometry and transmission electron microscopy revealed that SAT1 knockdown not only significantly reduced DDP-induced early, late, and total apoptosis rates (P < 0.05), but also markedly improved apoptotic features such as chromatin condensation and nuclear fragmentation in morphological terms. Western blotting results indicate that the expression levels of SAT1, IRE1α, XBP1s, GRP78, Caspase-12, and ATF6 proteins exhibited statistically significant differences (P < 0.05) across different treatment groups. Under DDP-induced endoplasmic reticulum stress conditions, silencing SAT1 upregulates GRP78 protein expression (P < 0.05) while downregulating IRE1α, ATF6, Caspase-12 and XBP1s expression (P < 0.05).Conclusion The study revealed that silencing the SAT1 gene may counteract cisplatin-induced cellular damage by regulating the GRP78/ATF6 pathway, thus identifying SAT1 as a potential novel therapeutic target for preventing and treating drug-induced ototoxicity.CCK-8 assays demonstrated that SAT1 knockdown significantly alleviated the proliferation-inhibitory effect of DDP on HEI-OC1 cells (P < 0.05).