VKORC1L1 Contributes to Glioblastoma Progression and Temozolomide Resistance by Sustaining Vitamin K Reduction and Limiting Ferroptosis-Associated Lipid Peroxidation

Objective To investigate the expression and functional role of vitamin K epoxide reductase complex subunit 1-like 1 (VKORC1L1) in glioblastoma (GBM) progression and temozolomide (TMZ) resistance. Methods VKORC1L1 expression and its associations with recurrence and overall survival were analyzed in the Chinese Glioma Genome Atlas. TMZ sensitivity and VKORC1L1 expression were examined in five GBM cell lines. VKORC1L1 was silenced in T98G cells, followed by evaluation of cell viability, migration, invasion, colony formation, ferroptosis-related markers, and the rescue effects of ferrostatin-1 (Fer-1). MK-4 and MK-4H₂ levels were quantified by LC-MS/MS, and TMZ sensitivity was determined by dose-response analysis. The effects of VKORC1L1 knockdown combined with TMZ were further examined in a T98G xenograft model. Results In the CGGA cohort, VKORC1L1 expression was elevated in recurrent gliomas and was associated with shorter overall survival. T98G cells showed the highest VKORC1L1 expression and greatest relative TMZ resistance among the five cell lines. VKORC1L1 knockdown increased ACSL4, lipid hydroperoxide, Fe²⁺, and 4-hydroxynonenal levels and suppressed T98G cell proliferation, migration, invasion, and colony formation, which were partially reversed by Fer-1. VKORC1L1 knockdown reduced MK-4H₂ generation and the MK-4H₂/MK-4 ratio and decreased the TMZ IC₅₀ from 623.7 μM in shNC cells to 351.4 and 398.4 μM in shVKORC1L1#1 and shVKORC1L1#2 cells, respectively. Fer-1 partially reversed this TMZ sensitization. In vivo , combined VKORC1L1 knockdown and TMZ treatment produced the smallest tumors, lowest Ki-67 index, and highest intratumoral 4-hydroxynonenal and Acsl4 expression. Conclusion VKORC1L1 contributes to GBM malignant behavior and TMZ resistance by sustaining vitamin K reduction and limiting ferroptosis-associated lipid peroxidation. These findings suggest that disruption of VKORC1L1-mediated vitamin K reduction may represent a potential strategy for enhancing TMZ sensitivity through increased ferroptosis-associated lipid peroxidation.