EGFR/ZBED1 reciprocal regulation promotes stemness and tumorigenesis in glioblastoma.

Background: Glioblastoma stem cells (GSCs), a stem-like tumorigenic subpopulation within glioblastoma (GBM), exhibit remarkable self-renewal capacity and therapeutic resistance. Zinc finger BED domain-containing protein 1 (ZBED1), a dual-function transcription factor and SUMO E3 ligase, has been implicated in oncogenic processes across malignancies, its functional role and regulatory mechanisms in GSCs remain enigmatic.

Methods: Multimodal approaches including immunohistochemistry, immunoblotting, and immunofluorescence were employed to evaluate ZBED1 expression patterns in GSCs and clinical GBM specimens. Functional characterization utilized in vitro models (proliferation assays, tumor-sphere formation assays, limiting dilution analysis) complemented by in vivo orthotopic xenograft models. Mechanistic investigations integrated RNA sequencing, label-free proteomics, chromatin immunoprecipitation (ChIP), immunohistochemistry, and western blotting to delineate the EGFR/ZBED1 regulatory axis.

Results: We demonstrated that ZBED1 was significantly upregulated in GSCs and linked to unfavorable prognosis. Genetic ablation of ZBED1 significantly impaired GSC proliferation and self-renewal capacity, while extending survival in xenograft models. Mechanistically, EGFR-mediated ZBED1 phosphorylation at tyrosine residues Y160/Y513 enhanced ZBED1-UBC9 interaction, promoting SUMOylation-dependent protein stabilization. Remarkably, ZBED1 reciprocally sustained EGFR expression through transcriptional repression of the E3 ubiquitin ligase PARK2, establishing a self-reinforcing EGFR/ZBED1/PARK2 signaling circuit critical for GSC maintenance.

Conclusions: Our findings elucidate a novel EGFR/ZBED1 positive feedback loop that drives GSC propagation and tumorigenesis, highlighting ZBED1 as an attractive candidate for therapeutic targeting in GBM.