Dynamic structural remodeling of LINC01956 enhances temozolomide resistance in <i>MGMT</i>-methylated glioblastoma.

Abstract

The mechanisms underlying stimuli-induced dynamic structural remodeling of RNAs for the maintenance of cellular physiological function and survival remain unclear. Here, we showed that in <i>MGMT</i> promoter-methylated glioblastoma (GBM), the RNA helicase DEAD-box helicase 46 (DDX46) is phosphorylated by temozolomide (TMZ)-activated checkpoint kinase 1 (CHK1), resulting in a dense-to-loose conformational change and an increase in DDX46 helicase activity. DDX46-mediated tertiary structural remodeling of LINC01956 exposes the binding motifs of LINC01956 to the 3' untranslated region of O⁶-methylguanine DNA methyltransferase (<i>MGMT</i>). This accelerates recruitment of <i>MGMT</i> mRNA to the RNA export machinery and transportation of <i>MGMT</i> mRNA from the nucleus to the cytoplasm, leading to increased MGMT abundance and TMZ resistance. Using patient-derived xenograft (PDX) and tumor organoid models, we found that treatment with the CHK1 inhibitor SRA737abolishes TMZ-induced structural remodeling of LINC01956 and subsequent MGMT up-regulation, resensitizing TMZ-resistant <i>MGMT</i> promoter-methylated GBM to TMZ. In conclusion, these findings highlight a mechanism underlying temozolomide-induced RNA structural remodeling and may represent a potential therapeutic strategy for patients with TMZ-resistant <i>MGMT</i> promoter-methylated GBM.