Sinapic Acid Reduces Hypoxia‐Induced Cell Damage in Hep‐2 Cells by Regulating TRPM2 Channel Activation

ABSTRACT

Hypoxia (HPX) is a significant pathological factor that contributes to mitochondrial dysfunction, oxidative stress, inflammation, and calcium dysregulation in laryngeal squamous cell carcinoma (LSCC). The redox‐sensitive TRPM2 channel is crucial for mediating HPX‐induced Ca ²⁺ excess and subsequent cell death. This study investigated whether sinapic acid (SPA), a natural phenolic compound with known antioxidant and anti‐inflammatory properties, can protect Hep‐2 cells from HPX‐induced injury by modulating TRPM2 activity. Hep‐2 cells were exposed to CoCl ₂ ‐induced HPX and treated with SPA (10–150 μM). Cell viability, oxidative stress parameters (malondialdehyde [MDA], glutathione [GSH], and reactive oxygen species [ROS]), intracellular Ca ²⁺ levels, mitochondrial membrane potential, and pro‐inflammatory cytokines (IL‐1β and TNF‐α), TRPM2 expression, and PI‐positive cell death were evaluated. HPX markedly decreased cell viability and increased oxidative and inflammatory responses, mitochondrial depolarization, and TRPM2‐dependent Ca ²⁺ influx. SPA significantly restored GSH levels, reduced MDA and ROS accumulation, suppressed cytokine production, and stabilized mitochondrial membrane potential. Moreover, SPA attenuated TRPM2 upregulation and effectively lowered Ca ²⁺ overload. Co‐treatment with the widely used TRPM2 channel inhibitor 2‐APB further enhanced SPA's protective effects and produced the greatest reduction in cell death. These findings demonstrate that SPA mitigates HPX‐induced cytotoxicity through antioxidative, anti‐inflammatory, and TRPM2‐modulating mechanisms, highlighting its potential therapeutic relevance in LSCC.