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

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 Ca²⁺ 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 CoCl₂-induced HPX and treated with SPA (10-150 μM). Cell viability, oxidative stress parameters (malondialdehyde [MDA], glutathione [GSH], and reactive oxygen species [ROS]), intracellular Ca²⁺ 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 Ca²⁺ 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 Ca²⁺ 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.