AbstractPaediatric high grade glioma are highly aggressive childhood brain tumours. Theprognosis is dire, with 2 year survival between 10 and 30%. For diffuse intrinsic pontineglioma (DIPG) patients, this is typically less than 1%. Despite decades of research, including significant advances in describing epigenetic modifications and subsequent genetic profilesof paediatric high grade glioma, there have been no changes to the standard of care for patients. Paediatric high grade glioma demonstrate widespread intrinsic and acquired resistance to current therapeutics, and treatment options are typically palliative rather than curative. There remains an urgent need to identify efficacious treatment strategies for these patients.
The cytotoxic role of clomipramine, a repurposed tricyclic antidepressant, was examined in a panel of paediatric high grade glioma cells. Clomipramine exposure significantly inhibited oxidative phosphorylation, mediating extensive metabolic reprogramming towards glycolytic dependency and concurrent induction of widespread macro-autophagy. In addition to macro-autophagy, clomipramine also induced highly selective mitophagy. Cytotoxicity was conserved across high and low grade paediatric gliomacell lines, at physiologically relevant glucose concentrations, and translated from 2D to 3D paediatric glioma models. Importantly, paediatric glioma cell death was demonstrated to be independent of apoptosis.
Gene essentiality and synthetically lethal interactions with clomipramine were determined by a genome wide CRISPR/Cas-9 knockout screen in the KNS42 paediatric high grade glioma cell line. This identified 16 synthetically lethal genes, silencing of which in combination with sustained low dose clomipramine exposure were cytotoxic.
These data together demonstrate that repurposing clomipramine shows therapeutic promise for intractable paediatric high grade glioma. The extensive metabolic reprogramming and autophagy induction following clomipramine exposure indicated significant regulatory cross-talk between these core survival pathways. This highlights atherapeutic sensitivity for paediatric high grade glioma which could be exploited with a combinatorial therapeutic approach of clomipramine, autophagy modulators and/ormetabolic inhibitors currently being tested in paediatric high grade glioma patients.
|Date of Award||Feb 2019|
|Supervisor||Richard Hill (Supervisor)|