The RNA-binding protein fragile-X mental retardation autosomal 1 (FXR1) modulates glioma cells sensitivity to temozolomide by regulating ferroptosis

Abstract

Temozolomide (TMZ) is a first-line chemotherapeutic agent for the treatment of glioma. However, at least 50% of glioma patients do not respond to TMZ, and the exact mechanism leading to TMZ resistance is still unclear. In the present study, we investigated molecular mechanisms underlying the resistance to TMZ in glioma cells. Glioma cell lines A172 and U251 were maintained in medium with increasing doses of TMZ for 12 months to induce the TMZ-resistance. Cells were then transduced with different adenoviral vectors to overexpress or inhibit RNA-binding protein fragile-X mental retardation autosomal 1 (FXR1) and glutathione peroxidase 4 (GPX4), which has been associated with the ferroptosis mechanism. Cell viability and cell death were analysed using cell counting Kit-8 (CCK-8) and Annexin V-FITC staining, respectively. RT-PCR, RNA-seq analysis, and RNA immunoprecipitation were used to analyse RNA expression; Western blot was used for protein expression. We discovered that RNA-binding protein fragile-X mental retardation autosomal 1 (FXR1) was upregulated in TMZ-resistance glioma. Knockdown of FXR1 could overcome TMZ-resistance by promoting ferroptosis. Mechanically, FXR1 could bind with GPX4 mRNA and positively regulate the expression of GPX4. Inhibition of GPX4 further increased the sensitivity to TMZ in glioma cells with upregulated FXR1. Our data suggest that targeting FXR1-GPX4 might be a potential strategy to overcome chemoresistance to TMZ in glioma cells.

Keywords: FXR1; Ferroptosis; Glioma; Temozolomide.