Glioportal: a comprehensive transcriptomic resource unveiling ligand-mediated mesenchymal transition in glioblastoma.

Background: Multi-omics profiling of glioblastoma (GBM) has unravelled two aspects fundamental to its aggressiveness and lethality that is molecular heterogeneity inherent to the tumour and cellular plasticity modulated by microenvironment. Yet, empirical validation to identify causal factors for these complex mechanisms is rather scarce. Here, we report our endeavour in establishing Glioportal, a GBM tumour biobank with derivative preclinical models and molecular information that we leverage for basic and translational research on precision therapies.

Methods: Bulk transcriptome and single-cell-based deconvolution analyses highlighted key features of distinct GBM subtypes and ligand-receptor pairs predicted to regulate malignant cell states plasticity. Synthetic genetic tracing tool and target genes/proteins expression analyses validated ligands-induced mesenchymal transition. This was further corroborated with phenotypic invasion/migration assays and cell-based assays using inhibitors, functional antibodies and gene silencing approaches. Proof-of-concept animal experiment was conducted using orthotopic xenograft carrying gene knockdown. Clinical relevance was assessed through immunohistochemical assay.

Results: Our transcriptomic analysis highlights the integral roles of STAT3 and NF-κB pathways in maintaining intrinsic mesenchymal identity and enabling myeloid-induced plasticity towards mesenchymal phenotype. One critical ligand, TNF, confers mesenchymal adaptation and cellular invasiveness that is mitigated by TNFRSF1A, but not TNFRSF1B, loss of function. TNFRSF1A silencing significantly improves survival in vivo.

Conclusion: Glioportal makes a valuable resource for identifying therapeutic vulnerabilities in molecularly stratified GBM. Here, we underscore GBM dependency on myeloid-derived ligands to acquire mesenchymal traits that has clinical implications in therapeutic response and recurrence. Such reliance warrants treatment strategies targeting ligand-receptor pairs to mitigate interactions with tumour ecosystem.