Asarinin attenuates ferroptosis resistance by inhibiting the activity of S-adenosyl homocysteine hydrolase in lung cancer

As a critical rate-limiting enzyme in the methionine cycle, S-adenosylhomocysteine hydrolase (AHCY) participates in intracellular cysteine synthesis. Its overexpression has been shown to induce Ferroptosis resistance in lung Cancer. However, naturally derived inhibitors of AHCY remain understudied. Here, we demonstrated that AHCY overexpression attenuates the ferroptosis-promoting effect of erastin by generating homocysteine (Hcy) and glutathione (GSH) in A549 cells. Virtual screening of Traditional Chinese Medicine Active Compound Library and subsequent experimental validation identified asarinin (Ar) as a bioactive natural product that enhances the efficacy of erastin by targeting AHCY. Ar potentiates erastin-induced lipid peroxidation and ROS production by suppressing Hcy and GSH synthesis. Consistently, the ferroptosis-sensitizing effect of Ar is abolished upon supplementation with Hcy and GSH. Biochemical assays revealed that Ar exhibits high binding affinity for AHCY, inhibits AHCY activity with an IC₅₀ of 22.1 µM, and increases AHCY protein stability. Molecular dynamics simulations indicated that Ar interacts with the H353 residue of AHCY. In lung Cancer xenograft model, Ar alone showed minimal antitumor effects but significantly enhanced the anti-tumor activity of erastin, demonstrating promising combination therapy potential. Our findings identify Ar as a naturally derived AHCY inhibitor with potential pharmacological effects in sensitizing Ferroptosis.