Deubiquitinase USP5 suppresses ferroptosis in lung adenocarcinoma by deubiquitinating and stabilizing GPX3

Abstract Ferroptosis is a regulated form of cell death driven by iron‐dependent lipid peroxidation and has emerged as a promising therapeutic target in nonsmall cell lung cancer (NSCLC). However, the specific mechanisms by which nonsmall cell lung cancer cells evade ferroptosis remain to be further elucidated. We conducted integrative transcriptomic analyses of published NSCLC datasets to identify ubiquitin‐specific proteases (USPs) potentially involved in the regulation of ferroptosis. Multiple USP proteins were screened and their prognostic significance evaluated, ultimately selecting USP5 for functional studies in two lung adenocarcinoma (LUAD) cell lines and patient‐derived LUAD organoids. Following treatment with the ferroptosis inducer erastin, survival rates and metastatic capacity were assessed. Ferroptosis was evaluated by measuring established ferroptotic markers and examining mitochondrial ultrastructure. Protein interactions were investigated using mass spectrometry, immunoprecipitation, and GST pull‐down assays. USP5 was significantly upregulated in LUAD tissues and correlated with poor patient prognosis. Functional experiments demonstrated that USP5 suppresses ferroptosis in LUAD cells treated with erastin, thereby promoting cell survival, proliferation, and invasiveness. Mechanistically, USP5 directly binds to and deubiquitinates GPX3, a key antioxidant enzyme, to enhance its stability. Rescue experiments confirmed that GPX3 is a functional mediator of USP5's ferroptosis‐inhibitory role. These findings are further supported in patient‐derived LUAD organoids. Our study identifies USP5 as a critical suppressor of ferroptosis in LUAD through its stabilization of GPX3, revealing a novel USP5–GPX3 regulatory axis that enables tumor resistance to oxidative stress. Targeting this pathway may represent a promising therapeutic strategy.