OLIG2-STAT5 cooperation supports glioma stem cell maintenance and proliferation in glioblastoma.

BACKGROUND

Glioblastoma (GBM) is driven, in part, by glioma stem cells (GSCs), which sustain therapeutic resistance and recurrence. OLIG2 is a key regulator of GSC programs but the signaling pathways that cooperate with Oligodendrocyte transcription factor 2 (OLIG2) to maintain GSC states remain incompletely defined. Although Signal transducer and activator of transcription (STAT) signaling has been implicated in GSC biology, work to date has focused primarily on STAT3, and the contribution of STAT5 remains poorly defined. Here, we investigated whether STAT5B functionally cooperates with OLIG2 in sustaining GSC phenotypes.

METHODS

Transcriptomic analyses, proximity ligation assays and biochemical studies were utilized to define OLIG2-STAT5B interactions in patient-derived GSCs. Functional consequences of OLIG2, STAT5B, BIRC5, and NUSAP1 suppression were assessed using small interfering RNA/short hairpin RNA-knockdown, stemness, and migration assays in EGFRvIII-expressing GSCs. In vivo tumor growth studies were performed using orthotopic xenograft models.

RESULTS

OLIG2 and STAT5B expression were positively correlated in GBM datasets and patient-derived models. OLIG2 physically associated with STAT5B in EGFRvIII-expressing GSCs, and loss of OLIG2 reduced STAT5 activation, supporting a functional link between these factors. OLIG2 or STAT5B suppression induced convergent transcriptional changes, including downregulation of genes associated with GSC maintenance and proliferation, notably stemness regulators BIRC5 and NUSAP1. Silencing BIRC5 or NUSAP1 impaired GSC self-renewal and migration. In orthotopic models, STAT5B knockdown prolonged survival and phenocopied OLIG2 suppression and stemness loss.

CONCLUSIONS

These findings identify STAT5B as a functional partner of OLIG2 in GBM and define anOLIG2-STAT5B transcriptional axis that sustains GSC maintenance and malignant behavior. Targeting this axis may represent a therapeutic strategy to disrupt treatment-refractory glioma cell states.