EGFR/ZBED1 reciprocal regulation promotes stemness and tumorigenesis in glioblastoma

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.

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, and 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.

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.

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.