Construction of a ferroptosis-related prognostic signature and identification of SRSF9 as a key biomarker in lung adenocarcinoma.

BACKGROUNDFerroptosis is a distinct form of regulated cell death characterized by iron-dependent lipid peroxidation, which plays crucial roles in tumor biology and therapeutic response. However, the prognostic significance of ferroptosis-related genes (FRGs) in lung adenocarcinoma (LUAD) remains incompletely understood. This study aimed to construct and validate a ferroptosis-related prognostic model for LUAD by integrating single-cell and bulk transcriptomic data.

METHODSSingle-cell RNA sequencing (scRNA-seq) data from GSE127465 were integrated with bulk transcriptomic data from The Cancer Genome Atlas lung adenocarcinoma cohort (TCGA-LUAD). FRGs were identified through single-cell gene set scoring with the AUCell algorithm and differential expression analysis. A least absolute shrinkage and selection operator (LASSO)-Cox regression model was constructed and externally validated using the GSE72094 and GSE68465 cohorts. Associations between the model, genomic features, and the tumor immune microenvironment were systematically analyzed. The functional role of SRSF9 was verified through in vitro experiments.

RESULTSA total of 93 candidate genes significantly associated with ferroptosis activity were identified, and an 8-gene prognostic signature (PEBP1, TXN, TIMP1, SRSF9, CFL1, OTUB1, FURIN, and PTPN6) was constructed. The signature demonstrated robust prognostic performance across validation cohorts, with time-dependent area under the curve (AUC) values ranging from 0.65 to 0.74. High-risk patients exhibited elevated tumor mutation burden (TMB) and distinct immune infiltration patterns. Consensus clustering analysis classified patients into two ferroptosis-related molecular subtypes with significantly different prognoses. Functional experiments demonstrated that SRSF9 knockdown inhibited LUAD cell proliferation, migration, and invasion. Moreover, SRSF9 knockdown downregulated glutathione peroxidase 4 (GPX4) and SLC7A11, increased lipid peroxidation and malondialdehyde (MDA) levels, and the resulting cell viability loss was rescued by ferrostatin-1, indicating that SRSF9 knockdown induces ferroptosis in LUAD cells.

CONCLUSIONSThe ferroptosis-related prognostic signature established in this study may facilitate risk stratification in LUAD patients. SRSF9 may regulate ferroptosis-related pathways through modulation of GPX4 and SLC7A11, and functional experiments further confirmed that SRSF9 knockdown induces ferroptosis in LUAD cells, highlighting SRSF9 as a candidate therapeutic target that warrants further investigation.