YBX1 phase separation promotes radioresistance in lung adenocarcinoma by suppressing ferroptosis through GPX4 regulation.

Abstract

Lung adenocarcinoma (LUAD) remains a leading cause of cancer-related mortality, and resistance to radiotherapy is a major clinical obstacle. Stress granules (SGs) are involved in tumor adaptation and therapy resistance, but the core regulatory network in LUAD is poorly defined. Here, we identified a 24-gene SG-related prognostic signature through LASSO analysis and singled out YBX1 as a core hub gene due to its high expression in LUAD and strong association with poor patient prognosis. Functional studies showed that YBX1 knockout (YBX1-KO) markedly sensitized LUAD cells to ionizing radiation (IR), as evidenced by reactive oxygen species (ROS) burst, glutathione (GSH) depletion, iron accumulation, and increased lipid peroxidation, all of which were reversed by the ferroptosis inhibitor Ferrostatin-1. Mechanistically, YBX1 directly bound to GPX4 mRNA through its cold shock domain (CSD) and enhanced GPX4 mRNA stability, thereby upregulating GPX4 expression and suppressing ferroptosis. Radiation stress promoted the interaction between YBX1 and the SG nucleating protein G3BP1 via YBX1 amino acids 240-253. Moreover, YBX1 underwent liquid-liquid phase separation (LLPS) through its C-terminal intrinsically disordered region (IDR), and YBX1 condensates co-localized with GPX4 mRNA. Disruption of the YBX1-G3BP1 interaction (Δ240-253) or deletion of the IDR abrogated the ability of YBX1 to stabilize GPX4 mRNA, suppress ferroptosis, and confer radioresistance. In orthotopic LUAD mouse models, YBX1 knockdown synergized with Erastin or IR to inhibit tumor growth, accompanied by enhanced ferroptosis. Together, these findings establish YBX1 as a central hub in the SG network that promotes radioresistance by forming phase-separated condensates that stabilize GPX4 mRNA and block ferroptosis. Targeting YBX1 or its phase separation represents a promising strategy to overcome radiotherapy resistance in LUAD.