To investigate the ability of patient derived glioma stem cells organoids to model the role of AHR in glioblastoma stem cells (GSCs) function and immune molecular programs in the dish as a patient’s avatar.

GSCs are highly self-renewing, resistant to therapy, and form lethal tumors. Organoids are defined as 3D in vitro tissue-like constructs derived from stem cells which mimic their corresponding in vivo organ. Aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, and key regulator of infiltrating immune cells in gliomas and associated with poor prognosis, but its role in GSC and GBMO biology is unknown.

Generation of glioblastoma organoids (GBMOs) from patient’s resected GBM surgical tissue. A total of 555 organoids were generated for the study.  We used limited dilution analysis for GSCs, in vivo transplantation of GSCs inactivated for AHR, small animal MRI. We used RNA microarray of GBMO treated with AHR agonist and antagonist, and CRISPR-Cas9 genetic ablation for AHR promote region in GSCs and GBMOs for validation of AHR immune gene targets.

 We show that AHR is a patient-specific regulator of the glioma intrinsic gene program in GSCs and GBMO that are enriched for AHR. We find that AHR is required for GSC self-renewal, GBMO expansion, radial glia-like cell proliferation, and expression of immune mediators seen in the mesenchymal subtype. CRISPR-Cas9 genetic ablation and pharmacological inhibition revealed that AHR regulates genes linked to intrinsic immunity, proliferation, and migration in GBMO. Genomic analysis of GBMO treated with AHR inhibitors identified expression signatures and candidate markers associated with survival of gliomas.

Our work defines the glioma intrinsic function of AHR in a model of early GBM formation, offering a rationale for clinical exploration of a potential ‘two-hit’ target of both GBM cells and infiltrating immune cells in patients with GBM expressing high levels of AHR.