Three-dimensional regulatory hubs support oncogenic programs in glioblastoma [ChIP-seq]

Enhancer-promoter communication in the context of the three-dimensional (3D) nucleus is critical for the regulation of transcriptional programs specific for cell identity. Here, we profile the 3D enhancer-promoter networks of primary patient-derived human glioma spheres (GSCs) in comparison with neuronal stem cells to identify candidate central nodes of GSC tumorigenic programs. We have identified highly interacting 3D enhancer-promoter “hubs” which strongly associate with robust and coordinated expression of tumor-associated genes, suggesting potentially central roles in the regulation of oncogenic programs. Integration of whole-genome sequencing (WGS) data from The Cancer Genome Atlas showed that 3D regulatory hubs are strongly enriched for recurrent point mutations in the larger cohort of glioblastoma patients. In a proof-of-concept experiment, epigenetic perturbation of a highly interacting and recurrent 3D enhancer hub in the GOLIM4 locus led to significant downregulation of multiple hub-connected genes and reduced clonogenicity along with a global shift in the transcriptional states. Finally, integration of published H3K27ac HiChIP from other cancer types enabled the identification of both “universal” and cancer type-specific 3D regulatory hubs which enrich for different oncogenic programs and potential regulators, and often associate with a worse prognosis. Overall, our study identifies complex 3D regulatory hubs in glioblastoma and provides computational and experimental support for their potential role in driving oncogenic programs and promoting tumorigenic properties.