TEAD4-driven GPX8 promotes temozolomide resistance in glioma by facilitating CTHRC1 expression to suppress mitochondrial oxidative stress.

Temozolomide (TMZ) resistance is a critical factor that affects the therapeutic efficacy in glioblastoma (GBM). Glutathione peroxidase 8 (GPX8), a ROS scavenging enzyme, is associated with poor prognosis in GBM. In this study, we comprehensively studied the role and mechanism of GPX8 in GBM resistance to TMZ. We found that GPX8 was upregulated in GBM cells, tissues, and TMZ-resistant GBM cells. In U87 TMZ-resistant cells, GPX8 knockdown significantly suppressed cell proliferation, reversed the epithelial-mesenchymal transition (EMT), and sensitized cells to TMZ. Moreover, GPX8 knockdown induced mitochondrial oxidative stress, leading to apoptosis in TMZ-resistant cells. TEA domain family member 4 (TEAD4) was upregulated in GBM cells and transactivates GPX8. GPX8 interacted with collagen triple helix repeat containing-1 (CTHRC1) and promoted its expression. Overexpression of TEAD4 or CTHRC1 reversed the suppressive effect of GPX8 knockdown on the malignant phenotypes of TMZ-resistant cells and antagonized its promotive effect on mitochondrial ROS generation and apoptosis. Furthermore, overexpression of GPX8 or CTHRC1 promoted EMT, reduced ROS levels, and lowered TMZ sensitivity in resistant cells. Crucially, the p38 MAPK/FOXO3 pathway inhibitor Ade was able to reverse these effects. GPX8 knockdown increased GBM sensitivity to TMZ, inhibited EMT, and elevated ROS levels in both xenograft models and glioma organoids. Overall, our results elucidated that TEAD4-driven GPX8 suppresses mitochondrial oxidative stress in TMZ-resistant cells through activation of the CTHRC1/p38 MAPK/FOXO3 pathway, which promotes TMZ resistance in GBM cells. These findings suggest that GPX8 may serve as a novel therapeutic target for overcoming TMZ resistance in GBM.