EXTH-34. ION CHANNELS AS A THERAPEUTIC TARGET IN PAEDIATRIC HIGH-GRADE GLIOMAS

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Abstract Pediatric Glioblastoma Multiforme (GBM) is a leading cause of CNS cancer-related death in children. The scarcity of treatments for GBM has opened the field to new pathways in adults, such as tumour treating fields(TTF). Studies have identified the clinical benefit of electrotherapy in combination with chemotherapeutics, however the mechanistic action is unclear. Increasing evidence suggests that ion channels not only regulate electrical signalling of excitable cells, but are also crucial in the development/progression of brain tumours. Ion channels are essential in cell-cycle control, invasion and migration of cancer cells, therefore presenting as valuable therapeutic targets. Candidate ion channel genes(ICG) associated with high-grade glioma (HGG) were identified via analysis of inhouse and publicly available data sets. Expression patterns of selected ICGs were assessed along with clinician correlations.. Protein and RNA expression of target ICGs was assessed in pGBM cell lines/ TMAs. Finally, the Human ClariomTMS array was used for whole transcriptome gene expression analysis of paediatric GBM cell lines treated with tumour treating fields or low frequency electrical fields via deep brain stimulating electrodes. Paediatric brain tumour cells were exposed to genetic and pharmacological manipulation of CLIC1 and CLIC4 ion channels individually or in combination. We have shown that HGG exhibit increased expression of CLIC4 and CLIC1 at protein and RNA levels in both publically available data sets and inhouse cell lines / TMAs. Clinical correlation determined that high CLIC4 and CLIC1 expression was associated with poor overall survival. Further to this, DNA array analysis revealed a downregulation of CLIC1 and CLIC4 ion channels genes in KNS42 cells when treated with electrotherapy compared to untreated cells. Inhibition of CLIC1 and CLIC4 reduces Cl- flux across cell membranes and reduces cell proliferation. These data provide rationale that manipulation of ICGs will reduce the capacity of childhood brain tumours to proliferate and invade.