A novel derivative of rhein overcomes temozolomide resistance in glioblastoma by regulating SOX9 through m6A methylation.

Temozolomide (TMZ) resistance remains a critical barrier to effective treatment of glioblastoma (GBM), the most aggressive form of glioma. Fat mass and obesity-associated protein (FTO), an m6A demethylase, has been implicated in tumor progression and chemoresistance. SYSUP007, a novel derivative of the FTO inhibitor rhein, exhibits anti-glioma activity; however, its role in modulating TMZ resistance remains unexplored. The present study aimed to investigate the mechanism by which SYSUP007 regulates TMZ resistance via FTO signaling. TMZ-resistant glioma cells were subjected to combinatorial treatment with SYSUP007 and TMZ. Cell proliferation was assessed using the MTT assay, while m6A dot blotting was employed to evaluate global m6A methylation levels. Western blotting and reverse transcription-polymerase chain reaction (RT-PCR) were performed to analyze FTO and downstream target expression. The results revealed that SYSUP007 inhibited glioma cell proliferation in a dose-dependent manner and synergistically enhanced TMZ sensitivity in vitro. SYSUP007 significantly suppressed FTO expression and elevated m6A methylation levels, concomitant with downregulation of the oncogenic FTO target SOX9. Notably, SOX9 expression was markedly upregulated in TMZ-resistant cells compared with parental cells, and SYSUP007 effectively reversed this phenotype. These findings suggest that SYSUP007 potentiates TMZ efficacy by targeting the FTO/m6A/SOX9 axis. As a single-molecule multi-target agent, SYSUP007 represents a promising therapeutic candidate to overcome TMZ resistance in glioma.