Cordycepin enhances radiosensitivity in oral squamous carcinoma cells by inducing autophagy and apoptosis through cell cycle arrest

Oral squamous cell carcinoma (OSCC) is one of the most common cancers worldwide and accounts for over 90% of malignant neoplasms of the oral cavity, with a 5-year survival rate of less than 50%. The long-term survival rate of OSCC patients has not markedly improved in recent decades due to its heterogeneous etiology and treatment outcomes. We investigated the anticancer effect of the combination of irradiation (IR) and cordycepin in the treatment of human OSCC cells in vitro. The type of cell death, especially autophagy and apoptosis, and the underlying mechanisms were examined. We found synergistic effects of cordycepin and IR on the viability of human oral cancer cells. The combination of cordycepin and IR treatment induced apoptosis, cell cycle arrest, and autophagic cell death. Furthermore, cordycepin induced S-phase arrest and prolonged G2/M arrest in the cells that received the combination treatment compared with those that received irradiation alone. Combined treatment induced the upregulation of ATG5 and p21 in an autophagy cascade-dependent manner, arrested the cell cycle in the G2/M phase, and repressed cell proliferation. Thus, we conclude that the combination of cordycepin and IR treatment could be a potential therapeutic strategy for OSCC.