Table 1_KDM5C-regulated SIX5 promotes glioblastoma progression through transcriptional activation of UBE2C and enhancement of the Warburg effect.docx

Gliomas are the most common primary malignant tumors of the adult central nervous system, characterized by rapid growth, high recurrence rates, and limited response to standard treatments, with median survival under 15 months. The SIX transcription factor family has been implicated in tumor development, but the role and regulatory mechanism of SIX5 in glioblastoma (GBM) remain unclear. This study systematically investigates the biological function of SIX5 and its regulatory network in GBM. Differential expression and weighted gene co-expression network analyses of GSE4290 and GSE50161 datasets, combined with machine learning algorithms including LASSO, identified SIX5 as a core candidate gene. Functional enrichment analyses and evaluation using TCGA and UALCAN databases revealed that SIX5 is highly expressed in GBM and associated with poor prognosis. Single-cell RNA sequencing and spatial transcriptomics showed enrichment of SIX5 in the tumor core and in astrocyte-like and stem cell-like subsets at the invasion front. In vitro, U87 and U251 cells with lentivirus-mediated SIX5 knockdown or overexpression were assessed for proliferation, migration, invasion, apoptosis, and colony formation. SIX5 knockdown significantly inhibited proliferation, migration, invasion, epithelial-mesenchymal transition, and tumorigenicity, while promoting apoptosis. Mechanistically, KDM5C positively regulates SIX5, which directly binds the UBE2C promoter to activate its transcription, enhancing AKT/mTOR signaling and promoting aerobic glycolysis via upregulation of GLUT1, HK2, PGK1, and LDHA. Rescue experiments showed that UBE2C overexpression partially restored malignant phenotypes under SIX5 downregulation. In vivo xenograft studies confirmed that the KDM5C–SIX5–UBE2C axis drives GBM growth. In conclusion, SIX5 functions as a critical oncogenic driver in GBM, regulated by KDM5C and promoting tumor progression through UBE2C-mediated activation of AKT/mTOR signaling and glycolytic reprogramming. The KDM5C–SIX5–UBE2C regulatory axis represents a potential prognostic biomarker and therapeutic target in glioblastoma.