Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. It is crucial to elucidate the mechanism underlying ferroptosis resistance in GBM. We used qRT-PCR to detect the level of DLEU1 and mRNAs of indicated genes, whereas protein levels were determined by Western blots. Fluorescence in situ hybridization assay (FISH) was applied to validate the sublocation of DLEU1 in GBM cells. Gene knockdown or overexpression was achieved by transient transfection. Ferroptosis markers were detected by indicated kits and transmission electron microscopy (TEM). RNA pull-down, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (CHIP)-qPCR, and dual-luciferase assay were used to validate the direct interaction between indicated key molecules in the current study. We validated that the expression of DLEU1 was upregulated in GBM samples. DLEU1 knockdown exacerbated erastin-induced ferroptosis in LN229 and U251MG cells, as well as in the xenograft model. Mechanistically, we found that DLEU1 bound with ZFP36 and facilitated ZFP36 to degrade ATF3 mRNA, thus upregulating the expression of SLC7A11 to attenuate erastin-induced ferroptosis. Importantly, our results confirmed that cancer-associated fibroblasts (CAFs) conferred ferroptosis resistance in GBM. The stimulation of CAF-conditioned medium enhanced the activation of HSF1, and HSF1 transcriptionally increased the level of DLEU1 to regulate erastin-induced ferroptosis. This study identified DLEU1 as an oncogenic lncRNA that epigenetically downregulates ATF3 expression via binding with ZFP36 to facilitate ferroptosis resistance in GBM. The upregulation of DLEU1 in GBM might be attributed to CAF-induced HSF1 activation. Our study might provide a research basis for understanding CAF-induced ferroptosis resistance in GBM.
Keywords: DLEU1; HSF1; cancer-associated fibroblasts; ferroptosis; glioblastoma multiforme.