Molecular characterization of STEAP3 in lung squamous cell carcinoma: Regulating EGFR to affect cell proliferation and ferroptosis.

Six-transmembrane epithelial antigen of the prostate 3 (STEAP3) has been reported to play a regulatory role in various types of cancers. However, its involvement in lung squamous cell carcinoma (LUSC) remains understudied. Here, we aimed to explore the biological functions and underlying mechanisms of STEAP3 in LUSC. Intersection genes associated with LUSC and ferroptosis were analyzed using the Venn method, STRING, GEPIA and UALCAN databases. The expression of STEAP3 was detected by qPCR and western blotting assay. Cell proliferation and viability were determined using the cell counting kit-8 assay and EDU staining. Oxidative stress and lipid peroxidation were measured by corresponding kits and DCFH-DA staining. Ferroptosis was evaluated by Phen Green SK and Western blot assay. The correlation between STEAP3 and EGFR was predicted by the TIMER and starBase database. Co-immunoprecipitation was conducted to verify the binding of STEAP3 and EGFR. The data demonstrated a significant upregulation of STEAP3 expression in LUSC cell lines. Silencing of STEAP3 suppressed H2170 cell viability and proliferation while promoting oxidative stress and lipid peroxidation through increased levels of MDA and ROS, as well as inhibited SOD activity. In addition, knockdown of STEAP3 induced ferroptosis through the regulation of ferroptosis-related proteins. Moreover, the binding between STEAP3 and EGFR was predicted and confirmed in LUSC. EGFR overexpression reversed the effects of STEAP3 silencing on H2170 cell viability, proliferation, oxidative stress, and ferroptosis. To summarize, the inhibition of STEAP3/EGFR may serve as a promising therapeutic target for LUSC treatment, as it can suppress LUSC proliferation and promote lipid peroxidation and ferroptosis.