Depletion of squalene epoxidase in synergy with glutathione peroxidase 4 inhibitor RSL3 overcomes oxidative stress resistance in lung squamous cell carcinoma

Lung squamous cell carcinoma (LUSC) lacks effective targeted therapies and has a poor prognosis. Disruption of squalene epoxidase (SQLE) has been implicated in metabolic disorders and cancer. However, the role of SQLE as a monooxygenase involved in oxidative stress remains unclear. Here, we investigated the unique role of SQLE expression in the diagnosis and prognosis prediction of LUSC. Knockdown of SQLE or treatment with the SQLE inhibitor terbinafine (TBF) can suppress the proliferation of LUSC cells by inducing apoptosis and reactive oxygen species (ROS) accumulation. However, depletion of SQLE also results in the impairment of lipid peroxidation and ferroptosis resistance such as upregulation of glutathione peroxidase 4 (GPX4). Therefore, prevention of SQLE in synergy with GPX4 inhibitor RSL3 effectively mitigates the proliferation and growth of LUSC. Our study indicates that the low expression of SQLE employs the adaptive survival through regulating the balance of apoptosis and resistance of ferroptosis. In future, the combinational therapy of targeting SQLE and ferroptosis could be a promising approach in treating LUSC.