RRM2 promotes lung adenocarcinoma progression and is associated with ferroptosis-inducer sensitivity through the NRF2/GPX4 signaling axis.
Abstract
Background
Lung adenocarcinoma (LUAD) is a leading cause of cancer-related mortality, characterized by aggressive progression and therapy resistance. Ferroptosis, an iron-dependent form of regulated cell death, has emerged as a promising therapeutic avenue. However, the role of Ribonucleotide Reductase M2 (RRM2) in ferroptosis regulation and its relevance to LUAD progression remain incompletely understood.
Methods
We integrated bulk transcriptomic, proteomic, WGCNA, and single-cell datasets to evaluate the clinical and biological relevance of RRM2 in LUAD. Functional validation was performed using RRM2 knockdown, ferroptosis-inducer sensitivity assays, ferroptosis-related biochemical assays, NRF2/GPX4 pathway analysis, rescue experiments, and xenograft models.
Results
RRM2 was significantly upregulated in LUAD tissues and was associated with poor overall survival. Single-cell analysis localized high RRM2 expression to a proliferative tumor cell subpopulation enriched in cell cycle- and immune-related pathways. Functionally, RRM2 knockdown suppressed LUAD cell proliferation and tumor growth and was accompanied by increased ROS, lipid ROS, Fe²⁺, and MDA levels and decreased GSH levels. RRM2 depletion also increased ferroptosis-inducer sensitivity, with enhanced erastin and RSL3 sensitivity in A549 cells and clear RSL3 sensitization in PC9 cells. In parallel, RRM2 silencing was associated with reduced NRF2 and GPX4 expression, decreased NRF2 nuclear-to-cytosolic signal intensity, and increased ACSL4 expression. NRF2 overexpression partially restored GPX4 immunofluorescence intensity in RRM2-knockdown cells. Moreover, NRF2 overexpression or Ferr-1 treatment partially reversed the growth-suppressive effects induced by RRM2 deficiency in vitro and in vivo.
Conclusion
RRM2 is associated with LUAD progression, ferroptosis-inducer sensitivity, and ferroptosis-related phenotypes, potentially through modulation of the NRF2/GPX4 axis. These findings support RRM2 as a candidate prognostic biomarker and a potential therapeutic target in LUAD, while the precise molecular relationship between RRM2 and the NRF2/GPX4 axis warrants further investigation.